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SIZING OF BENZENE WATER WASH SYSTEM
amp
PERFORMANCE EVALUATION OF RECYCLE GAS COMPRESSORS IN LAB FE PLANT
Report Submitted
by
DishaGardi
Under the guidance ofMr S Rangarajan
RelianceIndustries Limited
1 of 72
CERTIFICATE
This is to certify that this report is a bonafide record of the project work titled ldquoSizing of Benzene water wash system amp Performance evaluation of recycle gas compressors in LAB FE plantrdquo completed successfully by Ms DishaGardi MPSTME Mumbai
Mr S Rangarajan
CTS - LAB
RIL Patalganga
2 of 72
Acknowledgement
I feel indeed fortunate and privileged that I have got this rare opportunity to carry out my training at an esteemed organization like RIL
It is indeed a matter of great pleasure to express my sincere gratitude towards Ms Mankirat Kaur amp Ms Pallavi Joglekar whose encouragement co-operation and guidance and keen supervision and support at every stage of training inspired me in pursuing and completing the project I will be forever grateful to them for under their guidance I learned the correct tact and the never-say-die attitude
I also heartly thank the Head of Chemical Department and the faculty Supervisor DrAnantJhaveri for his valuable support and the friendly atmosphere of education provided by him and guidance in my endeavor to work on the project that will enhance my capabilities for my future studies and career
I would also like to acknowledge my sincere thanks to MrHareshOcchaney MrVasant Warke and Mr S Rangarajan who had mentored me during the training period I would also like to thank all the plant people who have provided me with the required knowledge and information I would also like to thank MrGaneshanShankarHR Manager of the company for his help and guidance without which the training would not have been possible
3 of 72
OBJECTIVES
The objectives of the training were
To understand the modern technologies applied for designing a chemical process plant
To develop an understanding of the working environment of the chemical industry
To build on the knowledge gathered in the college and understand its practical application
To get an insight to the modern chemical industry in the developing Indian economy
4 of 72
INDEX
Srno ContentsPROJECT-1
1 Introduction 2 Study of LAB process3 Alkylation unit4 Developed scheme5 Scheme description6 Calculation 7 Specification sheets
PROJECT-28 Introduction 9 Dew point10 Performance Evaluation of GB-601 AB11 Flash calculation for 1st stage12 Performance Evaluation of GB-602 ABC13 Flash calculation for 1st stage14 Flash calculation for 2nd stage15 Flash calculation for 3rd stage16 Flash calculation for 4th stage17 Safety measures in LAB plant
5 of 72
COMPANY INFORMATION
Reliance Industries Limited found by Dhirubhai H Ambani is Indiarsquos largest private sector enterprise with businesses in the energy and materials value chain Grouprsquos annual revenues are in excess of US$ 28 billion The flagship company of RIL is a Fortune Global 500 company and its largest private sector company in India
Backward vertical integration has been the cornerstone of the evolution and growth of Reliance Starting with textiles in the late seventies Reliance pursued a strategy of backward vertical integration in polyesters fibre intermediates plastics petrochemicals petroleum refining and oil and gas exploration and production ndash to be fully integrated along the materials and energy value chain
Reliance enjoys global leadership in its businesses being the largest polyester yarn and fibre producer in the world and among the top ten producers in the world in major petrochemical products
Major Group Companies are Reliance Industries Limited (including main subsidiary Reliance Retail Limted ) and Reliance Industrial Infrastructure Limited
6 of 72
LAB (Linear Alkyl Benzene) Process Overview
Introduction
The linear alkylbenzenes produced from C10-C13 linear olefins are useful detergent intermediates and can be readily sulfonated to yield linear alkylbenzensulfonates
HF acid catalystC10C13 olefins + Benzene Linear alkyl benzene (LAB)
SulfonationLinear Alkyl benzene (LAB) LAB sulfonates
These compounds constitute the ldquoactiverdquo ingredients of many household detergents They are surface-active compounds (surfactants) which are combined with various builders (often inorganic salts) to make up a detergent formula
BuildersLAB sulfonates House hold Detergents
Typical Detergent formulation
LAB sulfonates 25wt
Sodium tripolyphosphate 40 wt
Sodium silicate 10 wt
Sodium sulfate 16 wt
Water 8 wt
Carboxymethylcellulose 1 wt
7 of 72
History
During 1940rsquos and 1950rsquos the detergent market was primarily captured by dodecylbenzene (DDB) a product formed by alkylation of Benzene with propylene tetramer It was found that detergent formed by this was giving poor biodegradability of detergent
Propylene tetramer + Benzene Dodecylbenzene (DDB) (Low biodegradability)
Thus LAB introduced in early 60rsquos have substantially replaced this DDB which is having good biodegradability (gt95)
Process Description
Brief Overview
LAB manufacturing process is a technology patented by UOP Inc (Universal oil Product)
The LAB plant is divided into two parts called
a) Front Endb) Back End
In Front End Normal paraffin which is raw material for LAB is extracted from kerosene feed (UOP Molex unit)
UOP Molex unit Feed kerosene N paraffin (C10- C13) (Normal amp (Raw material for LAB) Non-normal paraffin)
8 of 72
In Back End this Normal paraffin is dehydrogenated to linear olefins (UOP Pacol unit)The linear olefins are then alkylated with benzene to LAB
UOP Pacol unit(Dehydrogenation)N paraffin (C10- C13) Linear Olefins (C10-C13)
HF acid catalystC10C13 olefins + Benzene Linear alkyl benzene (LAB)
Detail Description of Process
1) Front EndAs described earlier Normal paraffin (C10 to C13) is extracted from kerosene feed by UOP molex process The kerosene feed stock contains various carbon-chained compounds ranging from C7 to C17 This kerosene is processed in front end in series of processes they are
a) Prefractionation b) Hydrobon c) Molex
a) PREFRACTIONATION
The kerosene is fed to Prefractionation unit where heart cut kerosene of carbon chain C 10 to C14
is separated in two distillation columns in series
1) Stripper column
In this distillation column lighter compounds less than C10 are separated from top as
distillate The bottoms from the column is fed to second distillation column called
Rerun column
2) Rerun columnIn this column Heart cut kerosene of C10 to C14 is separated from top as distillate
9 of 72
STRIPPER
RERUN
Heart cut Kerosene (C10 to C14)
Light Kerosene
Feed kerosene
Heavy kerosene
b) HYDROBON
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit The catalyst used in Hydrobon reactor is S12 (Nickel ndashmolybdenumumoxide on alumina)
The heartcut kerosene from Prefractionation rerun column overhead is fed to this Hydrobon unit to remove sulfur nitrogen below 1 ppm This reaction is called as hydrotreating In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor
10 of 72
C-C-C-C-SH + H2 C-C-C-C + H2SOrganic sulfur(Mercaptan)
+ H2 C-C-C-C-C + NH3 N Nitrogen compound (Pyridine)
The reaction temperature is maintained at 310DegC while pressure is maintained at 65kgcm2g
The reactor temperature is maintained by charge heater where heat input is given by firing fuel
oil A recycle gas compressor and makeup gas compressor maintains the reactor pressure to 65
kgcm2g The H2 required for reaction is compressed in makeup gas compressor upto reactor
pressure
At reaction temperature cracking also takes place where some lighter (ltC10) are formed To
separate this the reactor effluent is passed to distillation column called Product Stripper The off
gases separated in stripper are burnt in heater as fuel
The H2S and NH3 formed in reaction form the ammonium sulfide salts The water is injected in
reactor effluent to prevent the deposition of salts that can corrode and foul the coolers The
desolved salts in water are further treated in sour water stripper to separate H2S and NH3 which
are burnt in heater as off gas
11 of 72
ProductSeparator
PRODUCT
STR
Lighters andOff gases
H2 from makeup gas compressor
Hydrobon reactor
To Molex unit
Charge heater
Feed from Prefractionation
Block Diagram of Hydrobon unit
c) MOLEX Molex process is effective method of separating normal paraffin from stream of hydrocarbon having normal and non-normal by physical selective adsorption process
The process uses solid adsorbent (Molecular sieve) where normal paraffin of straight chains are adsorbed in selective pores and non normal of branched chain are adsorbed in non selective pores
The adsorbed normal paraffin are then desorbed by normal pentane while non normal are desorbed by iso-octane
12 of 72
CHAMBER
CHAMBER
ROTARY VALVE
EXTRACT
RAFFINATE
Normal paraffin Non Normal
There are two adsorption chambers with 24 beds The process simulates countercurrent contact between fixed bed adsorbent and feed stream This simulation is done by flow directing device called ldquoRotary valverdquo
The separated streams from Molex chambers containing normal paraffin (Extract) and non normal (Raffinate) are fed to two distillation columns a) Extract column and b) Raffinate column In both distillation columns desorbent is separated from top and sidecut and recycled for desorption While bottom product of Extract column is Normal paraffin send to storage
E R
F
D
13 of 72
STRIPPER
RERUN
Heart cut Paraffin (C10 to C13)
Light NP
Feed NP
Heavy NP
2) Back EndAs described earlier Linear alkyl benzene (LAB) is produced from linear olefins by UOP detergent alkylation process The raw material normal paraffin of C10 to C14 from front end is processed in back end in series of processes they are
a) Prefractionation b) Pacol c) Alkylation
a) PREFRACTIONATION The normal paraffin of C10 to C14 carbon range is separated to Normal paraffin of C10 to C13 carbon range in two distillation columns in series
1) Stripper column In this distillation column lighter compound (if any) and partly C10 paraffin is removed as light normal paraffin (LNP) from top This LNP is sold in market as byproduct The bottoms is send to Rerun column
2) Rerun ColumnIn this column heartcut paraffin (C10 to C13) is separated from top as distillate The bottoms containing mainly C14 paraffin is sold in market as heavy normal paraffin (HNP) as byproduct
14 of 72
b) PACOL (Paraffin converted to olefin)
The normal paraffin of carbon range C10 to C13 is converted to linear olefins of carbon range C10 to C13 by Dehydrogenation reaction in UOP Pacol process
The catalyst used in reactor is alumina based platinum catalyst
Platinum catalyst
CH3-C-C-C-CH3 CH3 - C = C ndash C ndash CH3 + H2
N paraffin Linear Mono olefins
There are some side reactions takes places in Pacol they are
CH3 - C = C ndash C ndash CH3 CH3 - C = C = C ndash CH3 + H2
Linear Mono olefins Linear Di olefins
CH3 - C = C = C ndash CH3 Aromatics + H2
Linear Di olefins
As it is dehydrogenation reaction H2 gas is separated from reactor effluent in contact condenser and send to Front End for Hydrobon makeup gas compressor
Cracking also takes place in reactor where ltC10 paraffin and olefins are formed which is removed in distillation column called Pacol stripper The gas separated in stripper is burnt in heater as off gases
The reaction temperature is 470 to 495 DegC while pressure is kept low at 13 kgcm2g
The life of pacol catalyst is about 30 to 40 days As life of the catalyst is low there are two pacol reactors for continuous running of the plant
The conversion of paraffin is about 12 to 13
15 of 72
ContactCondenser
PACOL
STPR
Lighters andOff gases
Pacol reactor
To Alkylation
Charge heater
Normal ParaffinFeed
H2 to front end
DEFINE UNIT
The main purpose of this unit is to increase overall yield of LAB The Diolefins formed in Pacol reaction is converted to Mono olefins and normal paraffin thereby generating more LAB and lesser byproducts
The catalyst used in this reactor is Nickel based on alumina
Nickel catalyst
Diolefins + H2 Mono olefins
Diolefins + H2 Normal Paraffin
The reaction temperature is 180 DegC and pressure is 140 Kgcm2g
Block Diagram of Pacol Unit
16 of 72
IMIXER
2MIXER
HFSTRIPPER
C) ALKYLATION
As described earlier linear olefins (C10 to C13) are alkylated in this unit to form Linear alkyl Benzene (LAB) in presence of HF acid catalyst
The mono olefins are conveterd to Linear alkyl benzene (LAB) while diolefins are conveterd to Heavy alkyl Benzene (HAB) The aromatics are extracted in counter current extraction of HF acid and are separated in distillation column called Acid regenerators
HF acid catalyst
R- CH = CH ndashCH2 ndash Rrsquo + Benzene R-CH-CH2-CH2-Rrsquo
M Olefins
Where R and Rrsquo are alkyl groups (CH3) LAB
R-CH=CH-CH=CH-Rrsquo + 2 Benzene Heavy alkyl benzene
Di olefins HAB
The reaction is instantaneous and carried through a two stage mixer settler system The reactor section effluent is then processed in series of distillation columns where excess Benzene Paraffin LAB and byproduct Heavy alkyl benzene (HAB) gets separated
The separated benzene is recycled back to HF alkylation reactor while separated Paraffin is recycled to Pacol reactor for reaction The product Linear alkyl benzene (LAB) and byproduct Heavy alkyl benzene (HAB) are send to storage
The aromatics and non-normal which are formed in Pacol reaction are extracted in HF reaction unit by counter current extraction of HF acid as POLYMER This polymer is separated in Acid regenerators and then neutralized with KOH and send to storage
Block Diagram of Alkylation process
17 of 72
PROCESS INPUTS amp OUTPUTS
18 of 72
As described earlier plant is divided into two sections
a) Front End for Normal paraffin production from Keroseneb) Back End for Linear alkyl Benzene (LAB) production from N paraffin
The raw material kerosene is supplied to the plant from two sources
a) From Bharat Petroleum Corp Ltd Chembur (BPCL) via 55 Km pipelineb) From Reliance Petroleum Ltd Jamnagar via Shipping
The light kerosene heavy kerosene and Raffinate from front end are combined and send as return kerosene via pipeline or shipping to either BPCL or to RPL Jamnagar
The manufacturing of LAB is done in two grades
a) Domestic grade (Molecular weight 235 to 239)b) Export grade (Molecular weight 239 to 240)
The byproducts of LAB plant are
a) Light Normal paraffinb) Heavy normal paraffinc) Heavy alkyl Benzened) Tar polymer
Installed Capacities
A) For Normal Paraffin 115000 MT Highest prod 126596 MT in year 2001-2002
B) For LAB 100000 MT Highest prod 112484 MT in year 1999-2000
Plant load
A) For Normal Paraffin 117
B) For LAB 120 Production per day
A) For Normal Paraffin 330 MT day (Avrg)
B) For LAB 324 MTday (Avrg)
Customers
19 of 72
1) The Normal paraffin produced in LAB plant is normally used for captive consumption for producing LAB
2) The main customer of LAB is Ms Hindustan Lever and Procter amp Gamble Ltd and their subsidiary
3) The LAB is exported to Europe American African and Asian countries4) The light and Heavy normal paraffin is used to manufacture Chlorinated Paraffin Wax5) Heavy alkyl Benzene is used as lubricants in oil industry
Utility system in LAB plant
Hot oil system
There are two Hot oil Heaters available in LAB plant one for Front End and other is for Back End The Heaters are fired with furnace oil LSHS and off gases from process
The Hot oil (Dow Therm) which is thermic fluid is heated in these Hot oil heaters
The all heat inputs to the column preheater are given by circulating Hot oil at supply temperature of 330 DegC
Effluent System
The effluent generated in LAB plant mainly constitute
a) Fluoride Maximum limit lt 10 ppmb) Oil Maximum limit lt 10 ppm
For reduction of fluoride in effluent water LAB plant have two neutralisation basins where effluent from HF area is collected and then reacted with Lime (CaCO3) to reduce fluoride content below 10ppm
For reduction of oil in effluent water LAB plant have CPI separator installed to separate oil from effluent water The oil separated is send to Slope oil storage
In addition to this there is hydrocarbon pit installed in front end to collect pump and filter drains which is being blended in return kerosene to reduce oil load in effluent systemThere all oil collection pits installed in storm water channels to avoid oil going into the river via gates
20 of 72
Cooling water systemFor cooling the final products Byproducts to normal ambient temperatures the products byproducts are cooled in coolers The cooling media used is water There are three cooling towers installed in LAB planta) HF cooling tower it is separate cooling tower to avoid HF ingrace in coolers in non-HF
areab) Front End Cooling towerc) Back End cooling tower
Fin Fan coolers The distillation columns overheads are condensed in air-cooled fin fan coolers The advantage of these coolers over water-cooled coolers is low operating cost
Safety measures taken in LAB Plant
1) Safety Interlocks for tripping the operation of equipments in case process variables touches maximum allowable value
2) Flare system for burning excess gases from process3) Infra red detection system for Pacol Reactor and Hot pumps 4) Hydrocarbon detection system for detecting hydrocarbon leakages5) H2S detection system and siren for detecting H2S gas leakages 6) HF Detection system for detecting HF leakages7) Schedule HF leak testing of HF flanges8) Application of HF detection paints to all HF flanges to detect HF leak by decolouration9) Schedule Thickness survey of pipelines in HF area 10) Fire water sprinkler system for HF vessels Columns and pumps11) Fire water sprinkler system for Hot oil pumps12) Yellow boundary marking of HF area where personal protective equipments (PPErsquos) are
mandatory 13) Personal protective equipments (PPErsquos) for HF area Different types of PVC suits are defined
for different types of jobs ( A B C and D type)14) Separate breathing air reciprocating compressor for breathing air for C and D type PVC
suits in case of eemergency15) KOH scrubbing for venting from all HF equipments so that HF will not release into the
flare16) Daily Benzene monitoring with dragger tubes to detect any Benzene leaks from process17) Close draining system of HF and Benzene
21 of 72
PROJECT ndashI
The project is about developing a ldquoBENZENE-WATER WASHrdquo system to remove the impurities coming with fresh benzene that enters into benzene stripper and effects thefin-fan cooler The project is about developing such a scheme which will remove these impurities before entering the benzene stripper to eliminate the failure of fin-fan cooler
The scheme should also be such that it should not reduce the efficiency of the equipment and should be cost-effective
What is Benzene stripper
The high volatility of water dissolved in hydrocarbons is used in this column to obtain water-free benzene in the column bottoms which also removes any dissolved oxygen or non-condensibles in the benzene or off spec feeds Makeup benzene is fed to the overhead receiver on level control reset by the overhead receiver level controller It is refluxed via the overhead pump on flow control reset by the column bottom level controller and sent to the reaction section by the bottoms pump via the benzene stripper feedbottoms exchanger on flow control which is reset by the benzene column receiver level controller The benzene stripper receiver floats on the flare and is sized big enough to allow enough settling time for the water There is a small nitrogen flow via a conservation vent into the receiver vapor flare to maintain a slight nitrogen purge Water is collected in the boot and drained periodically whenever there is a boot high alarm Maintain a visible benzene water interface in the boot sight glass The benzene at the column bottom normally has a water content of less than 20ppm actually much lower if the column is operated well A moisture analyzer alarm high is provided The heat input to the column is provided by a hot oil reboiler with the hot oil flow controlled Off-spec material from the off-spec tank is normally rerun via the benzene stripper coming into the column receiver
What is the Issue
The benzene stripper column overheads are condensed in air-cooler (fin-fan coolers EC-301)The advantage of using this fin-fan cooler is the low operating cost no space constraint as are not on ground level etc This tube-bundle was failing at a frequency of once in a span of two years Failure analysis study was carried out and found that there are some impurities coming along with fresh benzene which are forming acidic solution after condensing in fin-fan This acidic solution formed was causing the repeated failure of tube-bundle
Water dosing was started upstream of the fin-fan bundle to dissolve out the impurities or to neutralize the acidic solution so that tubes can be saved This practice was started in 2008 Even after this modification the failures and continue and its difficult to analyze that what type of impurities are coming with benzene
22 of 72
So to eliminate this problem a scheme has been plotted to design a benzene scrubbing system This will be basically washing of benzene with DM water to remove the impurities before it enters the benzene stripper
The schematic diagram of this system is shown below
The scheme consists of a static mixture for mixing benzene and water for a particular residence time and at a particular velocity as required A gravity settler is for separating benzene and water on the basis of density difference
23 of 72
STATIC MIXER
This mixing device has no moving parts is simple and its cost can be quite reasonable when compared to mechanical driven mixers Static or motionless mixers are relatively new development and have proven to be effective for many specific and valuable process application It is useful for a wide range of viscosity fluids particularly useful in liquid-liquid mixing and also for some gas-liquid dispersion
The concept of motionless mixers is to achieve a uniform composition and temperature distribution in fluids flowing through the device The concept is build around a stationary rigid element placed in a pipe or cylinder that uses the energy of fluid flowing past to produce the mixing The unit becomes more efficient by adding additional static elements causing the flowing fluid elements to split rearrange recombine and split again to repeat the process lsquoxrsquo times for a uniform or homogeneous flowing stream is produced at discharge
Principle of operation
The static mixer unit is a series of fixed helical elements enclosed within a tubular housing
LIQUID ndash LIQUID SEPARATION(Decanters)
Separation of two liquid phases immiscible or partially miscible liquids is a common requirement in the process industries It is also frequently necessary to separate small quantities of entrained water from process streams The simplest form of equipment used to separate liquid phases is the gravity settling tank the decanter Various proprietary equipment is also used to promote coalescence and improve separation in difficult systems or where emulsions are likely to form Centrifugal separators are also used
Decanters (settlers)
Decanters are used to separate liquids where there is a sufficient difference in density between the liquids for the droplets to settle readily Decanters are essentially tanks which give sufficient residence time for the droplets of the dispersed phase to rise (or settle ) to the interface between the phases and coalesce
In an operating decanter there will be three distinct zones or bands clear heavy liquid separating dispersed liquid (the dispersion zone) and clear light liquid The position of the interface can be controlled with or without the use of instruments by use of a siphon take-off for the heavy liquid
24 of 72
Vertical decanter
The height of the take-off can be determined by making a pressure balance Neglecting friction loss in the pipes the pressure exerted by the combined height of the heavy and light liquid in the vessel must be balanced by the height of the heavy liquid in the take-off leg
(z1-z3)Ρ1g + z3 Ρ2g= z2 Ρ2g
z2 = (z1-z3) Ρ1 + z3 (1)Ρ2
WhereZ1= height from datum to light liquid overflow m Z2=height from datum to heavy liquid overflow m Z3=height from datum to interface m Ρ1=density of the light liquid kgmsup3 Ρ2=density of the heavy liquid kg msup3
The height of the liquid interface should be measured accurately when the liquid densities are close when one component is present only in small quantities or when the throughput is very small A typical scheme for the automatic control of the interface using a level instrument that can detect the position of the interface is shown in the diagram below Where one phase is present only in small amounts it is often recycled to the decanter feed to give more stable operation
25 of 72
CALCULATIONS
STATIC MIXER DESIGN
Required data
1 Physical properties of materials Density kgmsup3
Viscosity Pas = 0001Cp
2 Pressure drop Pressure drop in static mixer is best described by comparison with pipe flow
3 Geometrical parameters Diameter m
Type of static mixer constant (k)
Length (l) m
4 Process variables
Flow rate msup3s TemperaturedegC Pressure bar
26 of 72
Pressure drop calculation
a) Velocity (v)
V = Qπ4 Dsup2
b) Reynoldsrsquos number(Re)
Re= dvρμ
c) Pressure drop (Δp)For Re lt50 Δp =k1x μ x l xQd dsup3
k1= laminar flow constant
For Re gt10sup3 Δp =k2 x ρ x l x vsup2d 2
= k2 x Q x l x 8 x Qsup2d prodsup2 d⁴
k2= turbulent flow constant
Pipe diameter Flow seems to be turbulent as both the materials (B2+ H2O) are not viscous
D =39Q ⁰ ⁴⁵ ρ sup1sup3⁰
Q =52 + 572 = 1092msup3hr = 303 x 10macrsup3msup3s= 38564 ftsup3hr
Ρ = 926328 kgmsup3 =57828 lbftsup3
D =39 x Q ⁰ ⁴⁵ x ρ sup1sup3⁰
D =39 x (38564) ⁰ ⁴⁵ x (57828) sup1sup3⁰ 3600
D= 24 inch = 25 inch = 00635m
27 of 72
Velocity(v)
V =4 Q proddsup2
= 303 x 10macrsup3 msup3s x 4 314 x (00635)sup2
= 0957 ms (approx 1ms)
Reynoldrsquosnumber(Re)
Re = dvρ Μ = 00635 x 1 x 926328 0572
Re =103 x 10⁵
Thus the flow is highly turbulent
Flow regime Reynoldrsquos no(Re)
No of element No of elements to add if viscosity ratio between fluids exceeds 10001
No of elements to add if volumetric ratio between fluids exceeds 1001
Laminar lt1 24 6 61-10 18 6 611-50 14 6 651-100 12 6 6101-500 10 6 6
Transitional 501-1000 8 4 41001-2000 6 4 4
Turbulent 2001-5000 4 2 25001+ 2 2 2
Thus from the above table the mixer will have 2 elements
The mixer length will be based on the number of elements required An approximate length can be determined by multiplying the number of elements by 15
Mixer length = 15 x 2 =3
28 of 72
For turbulent flow applications it is generally recommended that a minimum velocity of 10 ftsec be maintained
V= 0408 x QDsup2 = 0408 x 4813sup2 = 218 ftsec =066 ms
DECANTER DESIGN
Benzene Water
Flow rate (msup3h) 52 572
Flow rate (kgh) 4543812 570311
Density (kgmsup3) 87381 99704
Viscosity (Pas) 0000604 000089
Take Dd = 150microm
microd = (150 Х 10ˉ⁶)sup2 Х 981 Х (87381-99704) 18 Х 000089
microd = -169787 Х 10ˉsup3 ms = -17 mms (rising)
As the flow rate is small we will use a vertical cylindrical vessel
The decanter vessel is sized on the basis that the velocity of the continuous phase must be less than settling velocity of the droplets of the dispersed phase Plug flow is assumed and the velocity of the continuous phase calculated using the area of the interfacemicroc =Lclt microdAiWhere microd = settling velocity of the dispersed phase droplets msmicroc = velocity of the continuous phase msLc = continuous phase volumetric flow rate msup3sAi = area of the interface msup2
29 of 72
Lc = 570311 X 1 99704 3600
= 00015889 msup3s
Ai=Lc = 00015889 microc 00017
= 0935817588 msup2
For a vertical cylindrical decanterAi = prodrsup2
r = 0935817588 prodr = 0545835318 m
Diameter= 1091670637 m
Taking the height as twice the diameter a reasonable value for a cylinder
Height = 2183341274 m
The position of the interface should be such that the band of droplets that collect at the interface waiting to coalesce and cross the interface does not extend to the bottom (or top) of the vessel The depth of the dispersion band is a function of the liquid flow rate and the interfacial area A value of to per cent of the decanter height is usually taken for the design purposes
Take the dispersion band as 10 per cent of the height = 021833mThe residence time of the droplets in the dispersion band = 021833 = 021833microd 00017 =1285926 s (approx 2 min)
This is satisfactory time a time of 2 to 5 min is normally recommended Thus the size of the water (continuous heavy phase) droplets that could be entrained with benzene (light phase) will be
Velocity of benzene phase = 4543812 X 1 X 1 873811 3600093581
=0001543511 ms =1543511mms
30 of 72
So from equation ( ) So the entrained droplet size will be =00015435 X 18 X 0000604 frac12 981 X (99704-873812)
=00001178 m=1178 microm
which is satisfactory below 150 microm
Piping arrangement
To minimize entrainment by the jet of liquid entering the vessel the inlet velocity for a decanter should keep below 1 ms
The velocity from static mixer= 066 ms
Flow rate= 4543812 + 570311 X 1 87381 99704 3600
= 0003033345msup3s
Area of pipe= flow ratevelocity
= 0003033345066
= 0004554572msup2
Pipe diameter =0004554572 x 4prod
= 0076158749 m =29983 inch (approx 3 in)
31 of 72
32 of 72
33 of 72
34 of 72
35 of 72
36 of 72
37 of 72
PROJECT II
CALULATING THE DEW POINT
This project is about the study and evaluation of the performance of the compressors in the Hydrobon section of the LAB plant which is installed to optimize the purity of hydrogen coming from the product separators The compressors in this section include recycle gas compressor and make-up gas compressorThe purity of hydrogen can be increased upto 90
This project will give the company an overall view of this loop The plant is running well about its installed capacity(131-140) The company wants to retain the purity level of nearly 90 for hydrogen even after operating above installed capacity Hence the current project will give the company an idea of the current hydrogen quality(purity) which is obtained and give an idea about changes if any to be made to existing process set-up
HYDROBON REACTOR
Hydrobon reactor is designed to remove contaminants present in the raw kerosene without changing the boiling range The hydrocarbon is passed through a 2 bed reactor feed with S 12 catalyst through a feed effluent exchanger and charge heater which maintain the required reaction temperature(310 c) The reaction required hydrogen gas which is supplied from pacol net gas generated from back end and tattoray hydrogen from PX plantThe reaction charge is heated to the reaction temperature in the charge heater enters the reactor from the top and is distributed over the catalyst bed Catalytic hydrogenation takes place in the reactor The impurities react with hydrogen and form salts which are subsequently separated and finally removed in sour water stripper The reactor effluents after separation is fed to the product stripper to remove lighters and hydrotreated kerosene is fed to molex unit The sulfur and nitrogen levels are reduced to 1 ppm or less
PARAMETERS DESIGN ACTUALPlant load() 100 115Hydrobon feed rate(mthr) 58 60Temperature 416 310Pressure (kgcm2 g) 822 62H2HC ratio 385 460Recycle hydrogen purity(mole)
75 min 95
Hydrobon feed specificationa Bromine
index(mg100gm)800 800
38 of 72
b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
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HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
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4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
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FLOW DIAGRAM OF HYDROBON SECTION
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Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
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nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
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Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
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DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
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ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
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Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
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Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
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Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
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=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
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Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
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Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
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Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
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Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
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Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
CERTIFICATE
This is to certify that this report is a bonafide record of the project work titled ldquoSizing of Benzene water wash system amp Performance evaluation of recycle gas compressors in LAB FE plantrdquo completed successfully by Ms DishaGardi MPSTME Mumbai
Mr S Rangarajan
CTS - LAB
RIL Patalganga
2 of 72
Acknowledgement
I feel indeed fortunate and privileged that I have got this rare opportunity to carry out my training at an esteemed organization like RIL
It is indeed a matter of great pleasure to express my sincere gratitude towards Ms Mankirat Kaur amp Ms Pallavi Joglekar whose encouragement co-operation and guidance and keen supervision and support at every stage of training inspired me in pursuing and completing the project I will be forever grateful to them for under their guidance I learned the correct tact and the never-say-die attitude
I also heartly thank the Head of Chemical Department and the faculty Supervisor DrAnantJhaveri for his valuable support and the friendly atmosphere of education provided by him and guidance in my endeavor to work on the project that will enhance my capabilities for my future studies and career
I would also like to acknowledge my sincere thanks to MrHareshOcchaney MrVasant Warke and Mr S Rangarajan who had mentored me during the training period I would also like to thank all the plant people who have provided me with the required knowledge and information I would also like to thank MrGaneshanShankarHR Manager of the company for his help and guidance without which the training would not have been possible
3 of 72
OBJECTIVES
The objectives of the training were
To understand the modern technologies applied for designing a chemical process plant
To develop an understanding of the working environment of the chemical industry
To build on the knowledge gathered in the college and understand its practical application
To get an insight to the modern chemical industry in the developing Indian economy
4 of 72
INDEX
Srno ContentsPROJECT-1
1 Introduction 2 Study of LAB process3 Alkylation unit4 Developed scheme5 Scheme description6 Calculation 7 Specification sheets
PROJECT-28 Introduction 9 Dew point10 Performance Evaluation of GB-601 AB11 Flash calculation for 1st stage12 Performance Evaluation of GB-602 ABC13 Flash calculation for 1st stage14 Flash calculation for 2nd stage15 Flash calculation for 3rd stage16 Flash calculation for 4th stage17 Safety measures in LAB plant
5 of 72
COMPANY INFORMATION
Reliance Industries Limited found by Dhirubhai H Ambani is Indiarsquos largest private sector enterprise with businesses in the energy and materials value chain Grouprsquos annual revenues are in excess of US$ 28 billion The flagship company of RIL is a Fortune Global 500 company and its largest private sector company in India
Backward vertical integration has been the cornerstone of the evolution and growth of Reliance Starting with textiles in the late seventies Reliance pursued a strategy of backward vertical integration in polyesters fibre intermediates plastics petrochemicals petroleum refining and oil and gas exploration and production ndash to be fully integrated along the materials and energy value chain
Reliance enjoys global leadership in its businesses being the largest polyester yarn and fibre producer in the world and among the top ten producers in the world in major petrochemical products
Major Group Companies are Reliance Industries Limited (including main subsidiary Reliance Retail Limted ) and Reliance Industrial Infrastructure Limited
6 of 72
LAB (Linear Alkyl Benzene) Process Overview
Introduction
The linear alkylbenzenes produced from C10-C13 linear olefins are useful detergent intermediates and can be readily sulfonated to yield linear alkylbenzensulfonates
HF acid catalystC10C13 olefins + Benzene Linear alkyl benzene (LAB)
SulfonationLinear Alkyl benzene (LAB) LAB sulfonates
These compounds constitute the ldquoactiverdquo ingredients of many household detergents They are surface-active compounds (surfactants) which are combined with various builders (often inorganic salts) to make up a detergent formula
BuildersLAB sulfonates House hold Detergents
Typical Detergent formulation
LAB sulfonates 25wt
Sodium tripolyphosphate 40 wt
Sodium silicate 10 wt
Sodium sulfate 16 wt
Water 8 wt
Carboxymethylcellulose 1 wt
7 of 72
History
During 1940rsquos and 1950rsquos the detergent market was primarily captured by dodecylbenzene (DDB) a product formed by alkylation of Benzene with propylene tetramer It was found that detergent formed by this was giving poor biodegradability of detergent
Propylene tetramer + Benzene Dodecylbenzene (DDB) (Low biodegradability)
Thus LAB introduced in early 60rsquos have substantially replaced this DDB which is having good biodegradability (gt95)
Process Description
Brief Overview
LAB manufacturing process is a technology patented by UOP Inc (Universal oil Product)
The LAB plant is divided into two parts called
a) Front Endb) Back End
In Front End Normal paraffin which is raw material for LAB is extracted from kerosene feed (UOP Molex unit)
UOP Molex unit Feed kerosene N paraffin (C10- C13) (Normal amp (Raw material for LAB) Non-normal paraffin)
8 of 72
In Back End this Normal paraffin is dehydrogenated to linear olefins (UOP Pacol unit)The linear olefins are then alkylated with benzene to LAB
UOP Pacol unit(Dehydrogenation)N paraffin (C10- C13) Linear Olefins (C10-C13)
HF acid catalystC10C13 olefins + Benzene Linear alkyl benzene (LAB)
Detail Description of Process
1) Front EndAs described earlier Normal paraffin (C10 to C13) is extracted from kerosene feed by UOP molex process The kerosene feed stock contains various carbon-chained compounds ranging from C7 to C17 This kerosene is processed in front end in series of processes they are
a) Prefractionation b) Hydrobon c) Molex
a) PREFRACTIONATION
The kerosene is fed to Prefractionation unit where heart cut kerosene of carbon chain C 10 to C14
is separated in two distillation columns in series
1) Stripper column
In this distillation column lighter compounds less than C10 are separated from top as
distillate The bottoms from the column is fed to second distillation column called
Rerun column
2) Rerun columnIn this column Heart cut kerosene of C10 to C14 is separated from top as distillate
9 of 72
STRIPPER
RERUN
Heart cut Kerosene (C10 to C14)
Light Kerosene
Feed kerosene
Heavy kerosene
b) HYDROBON
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit The catalyst used in Hydrobon reactor is S12 (Nickel ndashmolybdenumumoxide on alumina)
The heartcut kerosene from Prefractionation rerun column overhead is fed to this Hydrobon unit to remove sulfur nitrogen below 1 ppm This reaction is called as hydrotreating In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor
10 of 72
C-C-C-C-SH + H2 C-C-C-C + H2SOrganic sulfur(Mercaptan)
+ H2 C-C-C-C-C + NH3 N Nitrogen compound (Pyridine)
The reaction temperature is maintained at 310DegC while pressure is maintained at 65kgcm2g
The reactor temperature is maintained by charge heater where heat input is given by firing fuel
oil A recycle gas compressor and makeup gas compressor maintains the reactor pressure to 65
kgcm2g The H2 required for reaction is compressed in makeup gas compressor upto reactor
pressure
At reaction temperature cracking also takes place where some lighter (ltC10) are formed To
separate this the reactor effluent is passed to distillation column called Product Stripper The off
gases separated in stripper are burnt in heater as fuel
The H2S and NH3 formed in reaction form the ammonium sulfide salts The water is injected in
reactor effluent to prevent the deposition of salts that can corrode and foul the coolers The
desolved salts in water are further treated in sour water stripper to separate H2S and NH3 which
are burnt in heater as off gas
11 of 72
ProductSeparator
PRODUCT
STR
Lighters andOff gases
H2 from makeup gas compressor
Hydrobon reactor
To Molex unit
Charge heater
Feed from Prefractionation
Block Diagram of Hydrobon unit
c) MOLEX Molex process is effective method of separating normal paraffin from stream of hydrocarbon having normal and non-normal by physical selective adsorption process
The process uses solid adsorbent (Molecular sieve) where normal paraffin of straight chains are adsorbed in selective pores and non normal of branched chain are adsorbed in non selective pores
The adsorbed normal paraffin are then desorbed by normal pentane while non normal are desorbed by iso-octane
12 of 72
CHAMBER
CHAMBER
ROTARY VALVE
EXTRACT
RAFFINATE
Normal paraffin Non Normal
There are two adsorption chambers with 24 beds The process simulates countercurrent contact between fixed bed adsorbent and feed stream This simulation is done by flow directing device called ldquoRotary valverdquo
The separated streams from Molex chambers containing normal paraffin (Extract) and non normal (Raffinate) are fed to two distillation columns a) Extract column and b) Raffinate column In both distillation columns desorbent is separated from top and sidecut and recycled for desorption While bottom product of Extract column is Normal paraffin send to storage
E R
F
D
13 of 72
STRIPPER
RERUN
Heart cut Paraffin (C10 to C13)
Light NP
Feed NP
Heavy NP
2) Back EndAs described earlier Linear alkyl benzene (LAB) is produced from linear olefins by UOP detergent alkylation process The raw material normal paraffin of C10 to C14 from front end is processed in back end in series of processes they are
a) Prefractionation b) Pacol c) Alkylation
a) PREFRACTIONATION The normal paraffin of C10 to C14 carbon range is separated to Normal paraffin of C10 to C13 carbon range in two distillation columns in series
1) Stripper column In this distillation column lighter compound (if any) and partly C10 paraffin is removed as light normal paraffin (LNP) from top This LNP is sold in market as byproduct The bottoms is send to Rerun column
2) Rerun ColumnIn this column heartcut paraffin (C10 to C13) is separated from top as distillate The bottoms containing mainly C14 paraffin is sold in market as heavy normal paraffin (HNP) as byproduct
14 of 72
b) PACOL (Paraffin converted to olefin)
The normal paraffin of carbon range C10 to C13 is converted to linear olefins of carbon range C10 to C13 by Dehydrogenation reaction in UOP Pacol process
The catalyst used in reactor is alumina based platinum catalyst
Platinum catalyst
CH3-C-C-C-CH3 CH3 - C = C ndash C ndash CH3 + H2
N paraffin Linear Mono olefins
There are some side reactions takes places in Pacol they are
CH3 - C = C ndash C ndash CH3 CH3 - C = C = C ndash CH3 + H2
Linear Mono olefins Linear Di olefins
CH3 - C = C = C ndash CH3 Aromatics + H2
Linear Di olefins
As it is dehydrogenation reaction H2 gas is separated from reactor effluent in contact condenser and send to Front End for Hydrobon makeup gas compressor
Cracking also takes place in reactor where ltC10 paraffin and olefins are formed which is removed in distillation column called Pacol stripper The gas separated in stripper is burnt in heater as off gases
The reaction temperature is 470 to 495 DegC while pressure is kept low at 13 kgcm2g
The life of pacol catalyst is about 30 to 40 days As life of the catalyst is low there are two pacol reactors for continuous running of the plant
The conversion of paraffin is about 12 to 13
15 of 72
ContactCondenser
PACOL
STPR
Lighters andOff gases
Pacol reactor
To Alkylation
Charge heater
Normal ParaffinFeed
H2 to front end
DEFINE UNIT
The main purpose of this unit is to increase overall yield of LAB The Diolefins formed in Pacol reaction is converted to Mono olefins and normal paraffin thereby generating more LAB and lesser byproducts
The catalyst used in this reactor is Nickel based on alumina
Nickel catalyst
Diolefins + H2 Mono olefins
Diolefins + H2 Normal Paraffin
The reaction temperature is 180 DegC and pressure is 140 Kgcm2g
Block Diagram of Pacol Unit
16 of 72
IMIXER
2MIXER
HFSTRIPPER
C) ALKYLATION
As described earlier linear olefins (C10 to C13) are alkylated in this unit to form Linear alkyl Benzene (LAB) in presence of HF acid catalyst
The mono olefins are conveterd to Linear alkyl benzene (LAB) while diolefins are conveterd to Heavy alkyl Benzene (HAB) The aromatics are extracted in counter current extraction of HF acid and are separated in distillation column called Acid regenerators
HF acid catalyst
R- CH = CH ndashCH2 ndash Rrsquo + Benzene R-CH-CH2-CH2-Rrsquo
M Olefins
Where R and Rrsquo are alkyl groups (CH3) LAB
R-CH=CH-CH=CH-Rrsquo + 2 Benzene Heavy alkyl benzene
Di olefins HAB
The reaction is instantaneous and carried through a two stage mixer settler system The reactor section effluent is then processed in series of distillation columns where excess Benzene Paraffin LAB and byproduct Heavy alkyl benzene (HAB) gets separated
The separated benzene is recycled back to HF alkylation reactor while separated Paraffin is recycled to Pacol reactor for reaction The product Linear alkyl benzene (LAB) and byproduct Heavy alkyl benzene (HAB) are send to storage
The aromatics and non-normal which are formed in Pacol reaction are extracted in HF reaction unit by counter current extraction of HF acid as POLYMER This polymer is separated in Acid regenerators and then neutralized with KOH and send to storage
Block Diagram of Alkylation process
17 of 72
PROCESS INPUTS amp OUTPUTS
18 of 72
As described earlier plant is divided into two sections
a) Front End for Normal paraffin production from Keroseneb) Back End for Linear alkyl Benzene (LAB) production from N paraffin
The raw material kerosene is supplied to the plant from two sources
a) From Bharat Petroleum Corp Ltd Chembur (BPCL) via 55 Km pipelineb) From Reliance Petroleum Ltd Jamnagar via Shipping
The light kerosene heavy kerosene and Raffinate from front end are combined and send as return kerosene via pipeline or shipping to either BPCL or to RPL Jamnagar
The manufacturing of LAB is done in two grades
a) Domestic grade (Molecular weight 235 to 239)b) Export grade (Molecular weight 239 to 240)
The byproducts of LAB plant are
a) Light Normal paraffinb) Heavy normal paraffinc) Heavy alkyl Benzened) Tar polymer
Installed Capacities
A) For Normal Paraffin 115000 MT Highest prod 126596 MT in year 2001-2002
B) For LAB 100000 MT Highest prod 112484 MT in year 1999-2000
Plant load
A) For Normal Paraffin 117
B) For LAB 120 Production per day
A) For Normal Paraffin 330 MT day (Avrg)
B) For LAB 324 MTday (Avrg)
Customers
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1) The Normal paraffin produced in LAB plant is normally used for captive consumption for producing LAB
2) The main customer of LAB is Ms Hindustan Lever and Procter amp Gamble Ltd and their subsidiary
3) The LAB is exported to Europe American African and Asian countries4) The light and Heavy normal paraffin is used to manufacture Chlorinated Paraffin Wax5) Heavy alkyl Benzene is used as lubricants in oil industry
Utility system in LAB plant
Hot oil system
There are two Hot oil Heaters available in LAB plant one for Front End and other is for Back End The Heaters are fired with furnace oil LSHS and off gases from process
The Hot oil (Dow Therm) which is thermic fluid is heated in these Hot oil heaters
The all heat inputs to the column preheater are given by circulating Hot oil at supply temperature of 330 DegC
Effluent System
The effluent generated in LAB plant mainly constitute
a) Fluoride Maximum limit lt 10 ppmb) Oil Maximum limit lt 10 ppm
For reduction of fluoride in effluent water LAB plant have two neutralisation basins where effluent from HF area is collected and then reacted with Lime (CaCO3) to reduce fluoride content below 10ppm
For reduction of oil in effluent water LAB plant have CPI separator installed to separate oil from effluent water The oil separated is send to Slope oil storage
In addition to this there is hydrocarbon pit installed in front end to collect pump and filter drains which is being blended in return kerosene to reduce oil load in effluent systemThere all oil collection pits installed in storm water channels to avoid oil going into the river via gates
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Cooling water systemFor cooling the final products Byproducts to normal ambient temperatures the products byproducts are cooled in coolers The cooling media used is water There are three cooling towers installed in LAB planta) HF cooling tower it is separate cooling tower to avoid HF ingrace in coolers in non-HF
areab) Front End Cooling towerc) Back End cooling tower
Fin Fan coolers The distillation columns overheads are condensed in air-cooled fin fan coolers The advantage of these coolers over water-cooled coolers is low operating cost
Safety measures taken in LAB Plant
1) Safety Interlocks for tripping the operation of equipments in case process variables touches maximum allowable value
2) Flare system for burning excess gases from process3) Infra red detection system for Pacol Reactor and Hot pumps 4) Hydrocarbon detection system for detecting hydrocarbon leakages5) H2S detection system and siren for detecting H2S gas leakages 6) HF Detection system for detecting HF leakages7) Schedule HF leak testing of HF flanges8) Application of HF detection paints to all HF flanges to detect HF leak by decolouration9) Schedule Thickness survey of pipelines in HF area 10) Fire water sprinkler system for HF vessels Columns and pumps11) Fire water sprinkler system for Hot oil pumps12) Yellow boundary marking of HF area where personal protective equipments (PPErsquos) are
mandatory 13) Personal protective equipments (PPErsquos) for HF area Different types of PVC suits are defined
for different types of jobs ( A B C and D type)14) Separate breathing air reciprocating compressor for breathing air for C and D type PVC
suits in case of eemergency15) KOH scrubbing for venting from all HF equipments so that HF will not release into the
flare16) Daily Benzene monitoring with dragger tubes to detect any Benzene leaks from process17) Close draining system of HF and Benzene
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PROJECT ndashI
The project is about developing a ldquoBENZENE-WATER WASHrdquo system to remove the impurities coming with fresh benzene that enters into benzene stripper and effects thefin-fan cooler The project is about developing such a scheme which will remove these impurities before entering the benzene stripper to eliminate the failure of fin-fan cooler
The scheme should also be such that it should not reduce the efficiency of the equipment and should be cost-effective
What is Benzene stripper
The high volatility of water dissolved in hydrocarbons is used in this column to obtain water-free benzene in the column bottoms which also removes any dissolved oxygen or non-condensibles in the benzene or off spec feeds Makeup benzene is fed to the overhead receiver on level control reset by the overhead receiver level controller It is refluxed via the overhead pump on flow control reset by the column bottom level controller and sent to the reaction section by the bottoms pump via the benzene stripper feedbottoms exchanger on flow control which is reset by the benzene column receiver level controller The benzene stripper receiver floats on the flare and is sized big enough to allow enough settling time for the water There is a small nitrogen flow via a conservation vent into the receiver vapor flare to maintain a slight nitrogen purge Water is collected in the boot and drained periodically whenever there is a boot high alarm Maintain a visible benzene water interface in the boot sight glass The benzene at the column bottom normally has a water content of less than 20ppm actually much lower if the column is operated well A moisture analyzer alarm high is provided The heat input to the column is provided by a hot oil reboiler with the hot oil flow controlled Off-spec material from the off-spec tank is normally rerun via the benzene stripper coming into the column receiver
What is the Issue
The benzene stripper column overheads are condensed in air-cooler (fin-fan coolers EC-301)The advantage of using this fin-fan cooler is the low operating cost no space constraint as are not on ground level etc This tube-bundle was failing at a frequency of once in a span of two years Failure analysis study was carried out and found that there are some impurities coming along with fresh benzene which are forming acidic solution after condensing in fin-fan This acidic solution formed was causing the repeated failure of tube-bundle
Water dosing was started upstream of the fin-fan bundle to dissolve out the impurities or to neutralize the acidic solution so that tubes can be saved This practice was started in 2008 Even after this modification the failures and continue and its difficult to analyze that what type of impurities are coming with benzene
22 of 72
So to eliminate this problem a scheme has been plotted to design a benzene scrubbing system This will be basically washing of benzene with DM water to remove the impurities before it enters the benzene stripper
The schematic diagram of this system is shown below
The scheme consists of a static mixture for mixing benzene and water for a particular residence time and at a particular velocity as required A gravity settler is for separating benzene and water on the basis of density difference
23 of 72
STATIC MIXER
This mixing device has no moving parts is simple and its cost can be quite reasonable when compared to mechanical driven mixers Static or motionless mixers are relatively new development and have proven to be effective for many specific and valuable process application It is useful for a wide range of viscosity fluids particularly useful in liquid-liquid mixing and also for some gas-liquid dispersion
The concept of motionless mixers is to achieve a uniform composition and temperature distribution in fluids flowing through the device The concept is build around a stationary rigid element placed in a pipe or cylinder that uses the energy of fluid flowing past to produce the mixing The unit becomes more efficient by adding additional static elements causing the flowing fluid elements to split rearrange recombine and split again to repeat the process lsquoxrsquo times for a uniform or homogeneous flowing stream is produced at discharge
Principle of operation
The static mixer unit is a series of fixed helical elements enclosed within a tubular housing
LIQUID ndash LIQUID SEPARATION(Decanters)
Separation of two liquid phases immiscible or partially miscible liquids is a common requirement in the process industries It is also frequently necessary to separate small quantities of entrained water from process streams The simplest form of equipment used to separate liquid phases is the gravity settling tank the decanter Various proprietary equipment is also used to promote coalescence and improve separation in difficult systems or where emulsions are likely to form Centrifugal separators are also used
Decanters (settlers)
Decanters are used to separate liquids where there is a sufficient difference in density between the liquids for the droplets to settle readily Decanters are essentially tanks which give sufficient residence time for the droplets of the dispersed phase to rise (or settle ) to the interface between the phases and coalesce
In an operating decanter there will be three distinct zones or bands clear heavy liquid separating dispersed liquid (the dispersion zone) and clear light liquid The position of the interface can be controlled with or without the use of instruments by use of a siphon take-off for the heavy liquid
24 of 72
Vertical decanter
The height of the take-off can be determined by making a pressure balance Neglecting friction loss in the pipes the pressure exerted by the combined height of the heavy and light liquid in the vessel must be balanced by the height of the heavy liquid in the take-off leg
(z1-z3)Ρ1g + z3 Ρ2g= z2 Ρ2g
z2 = (z1-z3) Ρ1 + z3 (1)Ρ2
WhereZ1= height from datum to light liquid overflow m Z2=height from datum to heavy liquid overflow m Z3=height from datum to interface m Ρ1=density of the light liquid kgmsup3 Ρ2=density of the heavy liquid kg msup3
The height of the liquid interface should be measured accurately when the liquid densities are close when one component is present only in small quantities or when the throughput is very small A typical scheme for the automatic control of the interface using a level instrument that can detect the position of the interface is shown in the diagram below Where one phase is present only in small amounts it is often recycled to the decanter feed to give more stable operation
25 of 72
CALCULATIONS
STATIC MIXER DESIGN
Required data
1 Physical properties of materials Density kgmsup3
Viscosity Pas = 0001Cp
2 Pressure drop Pressure drop in static mixer is best described by comparison with pipe flow
3 Geometrical parameters Diameter m
Type of static mixer constant (k)
Length (l) m
4 Process variables
Flow rate msup3s TemperaturedegC Pressure bar
26 of 72
Pressure drop calculation
a) Velocity (v)
V = Qπ4 Dsup2
b) Reynoldsrsquos number(Re)
Re= dvρμ
c) Pressure drop (Δp)For Re lt50 Δp =k1x μ x l xQd dsup3
k1= laminar flow constant
For Re gt10sup3 Δp =k2 x ρ x l x vsup2d 2
= k2 x Q x l x 8 x Qsup2d prodsup2 d⁴
k2= turbulent flow constant
Pipe diameter Flow seems to be turbulent as both the materials (B2+ H2O) are not viscous
D =39Q ⁰ ⁴⁵ ρ sup1sup3⁰
Q =52 + 572 = 1092msup3hr = 303 x 10macrsup3msup3s= 38564 ftsup3hr
Ρ = 926328 kgmsup3 =57828 lbftsup3
D =39 x Q ⁰ ⁴⁵ x ρ sup1sup3⁰
D =39 x (38564) ⁰ ⁴⁵ x (57828) sup1sup3⁰ 3600
D= 24 inch = 25 inch = 00635m
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Velocity(v)
V =4 Q proddsup2
= 303 x 10macrsup3 msup3s x 4 314 x (00635)sup2
= 0957 ms (approx 1ms)
Reynoldrsquosnumber(Re)
Re = dvρ Μ = 00635 x 1 x 926328 0572
Re =103 x 10⁵
Thus the flow is highly turbulent
Flow regime Reynoldrsquos no(Re)
No of element No of elements to add if viscosity ratio between fluids exceeds 10001
No of elements to add if volumetric ratio between fluids exceeds 1001
Laminar lt1 24 6 61-10 18 6 611-50 14 6 651-100 12 6 6101-500 10 6 6
Transitional 501-1000 8 4 41001-2000 6 4 4
Turbulent 2001-5000 4 2 25001+ 2 2 2
Thus from the above table the mixer will have 2 elements
The mixer length will be based on the number of elements required An approximate length can be determined by multiplying the number of elements by 15
Mixer length = 15 x 2 =3
28 of 72
For turbulent flow applications it is generally recommended that a minimum velocity of 10 ftsec be maintained
V= 0408 x QDsup2 = 0408 x 4813sup2 = 218 ftsec =066 ms
DECANTER DESIGN
Benzene Water
Flow rate (msup3h) 52 572
Flow rate (kgh) 4543812 570311
Density (kgmsup3) 87381 99704
Viscosity (Pas) 0000604 000089
Take Dd = 150microm
microd = (150 Х 10ˉ⁶)sup2 Х 981 Х (87381-99704) 18 Х 000089
microd = -169787 Х 10ˉsup3 ms = -17 mms (rising)
As the flow rate is small we will use a vertical cylindrical vessel
The decanter vessel is sized on the basis that the velocity of the continuous phase must be less than settling velocity of the droplets of the dispersed phase Plug flow is assumed and the velocity of the continuous phase calculated using the area of the interfacemicroc =Lclt microdAiWhere microd = settling velocity of the dispersed phase droplets msmicroc = velocity of the continuous phase msLc = continuous phase volumetric flow rate msup3sAi = area of the interface msup2
29 of 72
Lc = 570311 X 1 99704 3600
= 00015889 msup3s
Ai=Lc = 00015889 microc 00017
= 0935817588 msup2
For a vertical cylindrical decanterAi = prodrsup2
r = 0935817588 prodr = 0545835318 m
Diameter= 1091670637 m
Taking the height as twice the diameter a reasonable value for a cylinder
Height = 2183341274 m
The position of the interface should be such that the band of droplets that collect at the interface waiting to coalesce and cross the interface does not extend to the bottom (or top) of the vessel The depth of the dispersion band is a function of the liquid flow rate and the interfacial area A value of to per cent of the decanter height is usually taken for the design purposes
Take the dispersion band as 10 per cent of the height = 021833mThe residence time of the droplets in the dispersion band = 021833 = 021833microd 00017 =1285926 s (approx 2 min)
This is satisfactory time a time of 2 to 5 min is normally recommended Thus the size of the water (continuous heavy phase) droplets that could be entrained with benzene (light phase) will be
Velocity of benzene phase = 4543812 X 1 X 1 873811 3600093581
=0001543511 ms =1543511mms
30 of 72
So from equation ( ) So the entrained droplet size will be =00015435 X 18 X 0000604 frac12 981 X (99704-873812)
=00001178 m=1178 microm
which is satisfactory below 150 microm
Piping arrangement
To minimize entrainment by the jet of liquid entering the vessel the inlet velocity for a decanter should keep below 1 ms
The velocity from static mixer= 066 ms
Flow rate= 4543812 + 570311 X 1 87381 99704 3600
= 0003033345msup3s
Area of pipe= flow ratevelocity
= 0003033345066
= 0004554572msup2
Pipe diameter =0004554572 x 4prod
= 0076158749 m =29983 inch (approx 3 in)
31 of 72
32 of 72
33 of 72
34 of 72
35 of 72
36 of 72
37 of 72
PROJECT II
CALULATING THE DEW POINT
This project is about the study and evaluation of the performance of the compressors in the Hydrobon section of the LAB plant which is installed to optimize the purity of hydrogen coming from the product separators The compressors in this section include recycle gas compressor and make-up gas compressorThe purity of hydrogen can be increased upto 90
This project will give the company an overall view of this loop The plant is running well about its installed capacity(131-140) The company wants to retain the purity level of nearly 90 for hydrogen even after operating above installed capacity Hence the current project will give the company an idea of the current hydrogen quality(purity) which is obtained and give an idea about changes if any to be made to existing process set-up
HYDROBON REACTOR
Hydrobon reactor is designed to remove contaminants present in the raw kerosene without changing the boiling range The hydrocarbon is passed through a 2 bed reactor feed with S 12 catalyst through a feed effluent exchanger and charge heater which maintain the required reaction temperature(310 c) The reaction required hydrogen gas which is supplied from pacol net gas generated from back end and tattoray hydrogen from PX plantThe reaction charge is heated to the reaction temperature in the charge heater enters the reactor from the top and is distributed over the catalyst bed Catalytic hydrogenation takes place in the reactor The impurities react with hydrogen and form salts which are subsequently separated and finally removed in sour water stripper The reactor effluents after separation is fed to the product stripper to remove lighters and hydrotreated kerosene is fed to molex unit The sulfur and nitrogen levels are reduced to 1 ppm or less
PARAMETERS DESIGN ACTUALPlant load() 100 115Hydrobon feed rate(mthr) 58 60Temperature 416 310Pressure (kgcm2 g) 822 62H2HC ratio 385 460Recycle hydrogen purity(mole)
75 min 95
Hydrobon feed specificationa Bromine
index(mg100gm)800 800
38 of 72
b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
39 of 72
HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
40 of 72
4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
41 of 72
FLOW DIAGRAM OF HYDROBON SECTION
42 of 72
Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
43 of 72
nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
44 of 72
Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
45 of 72
DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
46 of 72
DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
47 of 72
ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
48 of 72
Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
49 of 72
Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
50 of 72
Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
51 of 72
=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
52 of 72
Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
53 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
54 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
55 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
Acknowledgement
I feel indeed fortunate and privileged that I have got this rare opportunity to carry out my training at an esteemed organization like RIL
It is indeed a matter of great pleasure to express my sincere gratitude towards Ms Mankirat Kaur amp Ms Pallavi Joglekar whose encouragement co-operation and guidance and keen supervision and support at every stage of training inspired me in pursuing and completing the project I will be forever grateful to them for under their guidance I learned the correct tact and the never-say-die attitude
I also heartly thank the Head of Chemical Department and the faculty Supervisor DrAnantJhaveri for his valuable support and the friendly atmosphere of education provided by him and guidance in my endeavor to work on the project that will enhance my capabilities for my future studies and career
I would also like to acknowledge my sincere thanks to MrHareshOcchaney MrVasant Warke and Mr S Rangarajan who had mentored me during the training period I would also like to thank all the plant people who have provided me with the required knowledge and information I would also like to thank MrGaneshanShankarHR Manager of the company for his help and guidance without which the training would not have been possible
3 of 72
OBJECTIVES
The objectives of the training were
To understand the modern technologies applied for designing a chemical process plant
To develop an understanding of the working environment of the chemical industry
To build on the knowledge gathered in the college and understand its practical application
To get an insight to the modern chemical industry in the developing Indian economy
4 of 72
INDEX
Srno ContentsPROJECT-1
1 Introduction 2 Study of LAB process3 Alkylation unit4 Developed scheme5 Scheme description6 Calculation 7 Specification sheets
PROJECT-28 Introduction 9 Dew point10 Performance Evaluation of GB-601 AB11 Flash calculation for 1st stage12 Performance Evaluation of GB-602 ABC13 Flash calculation for 1st stage14 Flash calculation for 2nd stage15 Flash calculation for 3rd stage16 Flash calculation for 4th stage17 Safety measures in LAB plant
5 of 72
COMPANY INFORMATION
Reliance Industries Limited found by Dhirubhai H Ambani is Indiarsquos largest private sector enterprise with businesses in the energy and materials value chain Grouprsquos annual revenues are in excess of US$ 28 billion The flagship company of RIL is a Fortune Global 500 company and its largest private sector company in India
Backward vertical integration has been the cornerstone of the evolution and growth of Reliance Starting with textiles in the late seventies Reliance pursued a strategy of backward vertical integration in polyesters fibre intermediates plastics petrochemicals petroleum refining and oil and gas exploration and production ndash to be fully integrated along the materials and energy value chain
Reliance enjoys global leadership in its businesses being the largest polyester yarn and fibre producer in the world and among the top ten producers in the world in major petrochemical products
Major Group Companies are Reliance Industries Limited (including main subsidiary Reliance Retail Limted ) and Reliance Industrial Infrastructure Limited
6 of 72
LAB (Linear Alkyl Benzene) Process Overview
Introduction
The linear alkylbenzenes produced from C10-C13 linear olefins are useful detergent intermediates and can be readily sulfonated to yield linear alkylbenzensulfonates
HF acid catalystC10C13 olefins + Benzene Linear alkyl benzene (LAB)
SulfonationLinear Alkyl benzene (LAB) LAB sulfonates
These compounds constitute the ldquoactiverdquo ingredients of many household detergents They are surface-active compounds (surfactants) which are combined with various builders (often inorganic salts) to make up a detergent formula
BuildersLAB sulfonates House hold Detergents
Typical Detergent formulation
LAB sulfonates 25wt
Sodium tripolyphosphate 40 wt
Sodium silicate 10 wt
Sodium sulfate 16 wt
Water 8 wt
Carboxymethylcellulose 1 wt
7 of 72
History
During 1940rsquos and 1950rsquos the detergent market was primarily captured by dodecylbenzene (DDB) a product formed by alkylation of Benzene with propylene tetramer It was found that detergent formed by this was giving poor biodegradability of detergent
Propylene tetramer + Benzene Dodecylbenzene (DDB) (Low biodegradability)
Thus LAB introduced in early 60rsquos have substantially replaced this DDB which is having good biodegradability (gt95)
Process Description
Brief Overview
LAB manufacturing process is a technology patented by UOP Inc (Universal oil Product)
The LAB plant is divided into two parts called
a) Front Endb) Back End
In Front End Normal paraffin which is raw material for LAB is extracted from kerosene feed (UOP Molex unit)
UOP Molex unit Feed kerosene N paraffin (C10- C13) (Normal amp (Raw material for LAB) Non-normal paraffin)
8 of 72
In Back End this Normal paraffin is dehydrogenated to linear olefins (UOP Pacol unit)The linear olefins are then alkylated with benzene to LAB
UOP Pacol unit(Dehydrogenation)N paraffin (C10- C13) Linear Olefins (C10-C13)
HF acid catalystC10C13 olefins + Benzene Linear alkyl benzene (LAB)
Detail Description of Process
1) Front EndAs described earlier Normal paraffin (C10 to C13) is extracted from kerosene feed by UOP molex process The kerosene feed stock contains various carbon-chained compounds ranging from C7 to C17 This kerosene is processed in front end in series of processes they are
a) Prefractionation b) Hydrobon c) Molex
a) PREFRACTIONATION
The kerosene is fed to Prefractionation unit where heart cut kerosene of carbon chain C 10 to C14
is separated in two distillation columns in series
1) Stripper column
In this distillation column lighter compounds less than C10 are separated from top as
distillate The bottoms from the column is fed to second distillation column called
Rerun column
2) Rerun columnIn this column Heart cut kerosene of C10 to C14 is separated from top as distillate
9 of 72
STRIPPER
RERUN
Heart cut Kerosene (C10 to C14)
Light Kerosene
Feed kerosene
Heavy kerosene
b) HYDROBON
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit The catalyst used in Hydrobon reactor is S12 (Nickel ndashmolybdenumumoxide on alumina)
The heartcut kerosene from Prefractionation rerun column overhead is fed to this Hydrobon unit to remove sulfur nitrogen below 1 ppm This reaction is called as hydrotreating In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor
10 of 72
C-C-C-C-SH + H2 C-C-C-C + H2SOrganic sulfur(Mercaptan)
+ H2 C-C-C-C-C + NH3 N Nitrogen compound (Pyridine)
The reaction temperature is maintained at 310DegC while pressure is maintained at 65kgcm2g
The reactor temperature is maintained by charge heater where heat input is given by firing fuel
oil A recycle gas compressor and makeup gas compressor maintains the reactor pressure to 65
kgcm2g The H2 required for reaction is compressed in makeup gas compressor upto reactor
pressure
At reaction temperature cracking also takes place where some lighter (ltC10) are formed To
separate this the reactor effluent is passed to distillation column called Product Stripper The off
gases separated in stripper are burnt in heater as fuel
The H2S and NH3 formed in reaction form the ammonium sulfide salts The water is injected in
reactor effluent to prevent the deposition of salts that can corrode and foul the coolers The
desolved salts in water are further treated in sour water stripper to separate H2S and NH3 which
are burnt in heater as off gas
11 of 72
ProductSeparator
PRODUCT
STR
Lighters andOff gases
H2 from makeup gas compressor
Hydrobon reactor
To Molex unit
Charge heater
Feed from Prefractionation
Block Diagram of Hydrobon unit
c) MOLEX Molex process is effective method of separating normal paraffin from stream of hydrocarbon having normal and non-normal by physical selective adsorption process
The process uses solid adsorbent (Molecular sieve) where normal paraffin of straight chains are adsorbed in selective pores and non normal of branched chain are adsorbed in non selective pores
The adsorbed normal paraffin are then desorbed by normal pentane while non normal are desorbed by iso-octane
12 of 72
CHAMBER
CHAMBER
ROTARY VALVE
EXTRACT
RAFFINATE
Normal paraffin Non Normal
There are two adsorption chambers with 24 beds The process simulates countercurrent contact between fixed bed adsorbent and feed stream This simulation is done by flow directing device called ldquoRotary valverdquo
The separated streams from Molex chambers containing normal paraffin (Extract) and non normal (Raffinate) are fed to two distillation columns a) Extract column and b) Raffinate column In both distillation columns desorbent is separated from top and sidecut and recycled for desorption While bottom product of Extract column is Normal paraffin send to storage
E R
F
D
13 of 72
STRIPPER
RERUN
Heart cut Paraffin (C10 to C13)
Light NP
Feed NP
Heavy NP
2) Back EndAs described earlier Linear alkyl benzene (LAB) is produced from linear olefins by UOP detergent alkylation process The raw material normal paraffin of C10 to C14 from front end is processed in back end in series of processes they are
a) Prefractionation b) Pacol c) Alkylation
a) PREFRACTIONATION The normal paraffin of C10 to C14 carbon range is separated to Normal paraffin of C10 to C13 carbon range in two distillation columns in series
1) Stripper column In this distillation column lighter compound (if any) and partly C10 paraffin is removed as light normal paraffin (LNP) from top This LNP is sold in market as byproduct The bottoms is send to Rerun column
2) Rerun ColumnIn this column heartcut paraffin (C10 to C13) is separated from top as distillate The bottoms containing mainly C14 paraffin is sold in market as heavy normal paraffin (HNP) as byproduct
14 of 72
b) PACOL (Paraffin converted to olefin)
The normal paraffin of carbon range C10 to C13 is converted to linear olefins of carbon range C10 to C13 by Dehydrogenation reaction in UOP Pacol process
The catalyst used in reactor is alumina based platinum catalyst
Platinum catalyst
CH3-C-C-C-CH3 CH3 - C = C ndash C ndash CH3 + H2
N paraffin Linear Mono olefins
There are some side reactions takes places in Pacol they are
CH3 - C = C ndash C ndash CH3 CH3 - C = C = C ndash CH3 + H2
Linear Mono olefins Linear Di olefins
CH3 - C = C = C ndash CH3 Aromatics + H2
Linear Di olefins
As it is dehydrogenation reaction H2 gas is separated from reactor effluent in contact condenser and send to Front End for Hydrobon makeup gas compressor
Cracking also takes place in reactor where ltC10 paraffin and olefins are formed which is removed in distillation column called Pacol stripper The gas separated in stripper is burnt in heater as off gases
The reaction temperature is 470 to 495 DegC while pressure is kept low at 13 kgcm2g
The life of pacol catalyst is about 30 to 40 days As life of the catalyst is low there are two pacol reactors for continuous running of the plant
The conversion of paraffin is about 12 to 13
15 of 72
ContactCondenser
PACOL
STPR
Lighters andOff gases
Pacol reactor
To Alkylation
Charge heater
Normal ParaffinFeed
H2 to front end
DEFINE UNIT
The main purpose of this unit is to increase overall yield of LAB The Diolefins formed in Pacol reaction is converted to Mono olefins and normal paraffin thereby generating more LAB and lesser byproducts
The catalyst used in this reactor is Nickel based on alumina
Nickel catalyst
Diolefins + H2 Mono olefins
Diolefins + H2 Normal Paraffin
The reaction temperature is 180 DegC and pressure is 140 Kgcm2g
Block Diagram of Pacol Unit
16 of 72
IMIXER
2MIXER
HFSTRIPPER
C) ALKYLATION
As described earlier linear olefins (C10 to C13) are alkylated in this unit to form Linear alkyl Benzene (LAB) in presence of HF acid catalyst
The mono olefins are conveterd to Linear alkyl benzene (LAB) while diolefins are conveterd to Heavy alkyl Benzene (HAB) The aromatics are extracted in counter current extraction of HF acid and are separated in distillation column called Acid regenerators
HF acid catalyst
R- CH = CH ndashCH2 ndash Rrsquo + Benzene R-CH-CH2-CH2-Rrsquo
M Olefins
Where R and Rrsquo are alkyl groups (CH3) LAB
R-CH=CH-CH=CH-Rrsquo + 2 Benzene Heavy alkyl benzene
Di olefins HAB
The reaction is instantaneous and carried through a two stage mixer settler system The reactor section effluent is then processed in series of distillation columns where excess Benzene Paraffin LAB and byproduct Heavy alkyl benzene (HAB) gets separated
The separated benzene is recycled back to HF alkylation reactor while separated Paraffin is recycled to Pacol reactor for reaction The product Linear alkyl benzene (LAB) and byproduct Heavy alkyl benzene (HAB) are send to storage
The aromatics and non-normal which are formed in Pacol reaction are extracted in HF reaction unit by counter current extraction of HF acid as POLYMER This polymer is separated in Acid regenerators and then neutralized with KOH and send to storage
Block Diagram of Alkylation process
17 of 72
PROCESS INPUTS amp OUTPUTS
18 of 72
As described earlier plant is divided into two sections
a) Front End for Normal paraffin production from Keroseneb) Back End for Linear alkyl Benzene (LAB) production from N paraffin
The raw material kerosene is supplied to the plant from two sources
a) From Bharat Petroleum Corp Ltd Chembur (BPCL) via 55 Km pipelineb) From Reliance Petroleum Ltd Jamnagar via Shipping
The light kerosene heavy kerosene and Raffinate from front end are combined and send as return kerosene via pipeline or shipping to either BPCL or to RPL Jamnagar
The manufacturing of LAB is done in two grades
a) Domestic grade (Molecular weight 235 to 239)b) Export grade (Molecular weight 239 to 240)
The byproducts of LAB plant are
a) Light Normal paraffinb) Heavy normal paraffinc) Heavy alkyl Benzened) Tar polymer
Installed Capacities
A) For Normal Paraffin 115000 MT Highest prod 126596 MT in year 2001-2002
B) For LAB 100000 MT Highest prod 112484 MT in year 1999-2000
Plant load
A) For Normal Paraffin 117
B) For LAB 120 Production per day
A) For Normal Paraffin 330 MT day (Avrg)
B) For LAB 324 MTday (Avrg)
Customers
19 of 72
1) The Normal paraffin produced in LAB plant is normally used for captive consumption for producing LAB
2) The main customer of LAB is Ms Hindustan Lever and Procter amp Gamble Ltd and their subsidiary
3) The LAB is exported to Europe American African and Asian countries4) The light and Heavy normal paraffin is used to manufacture Chlorinated Paraffin Wax5) Heavy alkyl Benzene is used as lubricants in oil industry
Utility system in LAB plant
Hot oil system
There are two Hot oil Heaters available in LAB plant one for Front End and other is for Back End The Heaters are fired with furnace oil LSHS and off gases from process
The Hot oil (Dow Therm) which is thermic fluid is heated in these Hot oil heaters
The all heat inputs to the column preheater are given by circulating Hot oil at supply temperature of 330 DegC
Effluent System
The effluent generated in LAB plant mainly constitute
a) Fluoride Maximum limit lt 10 ppmb) Oil Maximum limit lt 10 ppm
For reduction of fluoride in effluent water LAB plant have two neutralisation basins where effluent from HF area is collected and then reacted with Lime (CaCO3) to reduce fluoride content below 10ppm
For reduction of oil in effluent water LAB plant have CPI separator installed to separate oil from effluent water The oil separated is send to Slope oil storage
In addition to this there is hydrocarbon pit installed in front end to collect pump and filter drains which is being blended in return kerosene to reduce oil load in effluent systemThere all oil collection pits installed in storm water channels to avoid oil going into the river via gates
20 of 72
Cooling water systemFor cooling the final products Byproducts to normal ambient temperatures the products byproducts are cooled in coolers The cooling media used is water There are three cooling towers installed in LAB planta) HF cooling tower it is separate cooling tower to avoid HF ingrace in coolers in non-HF
areab) Front End Cooling towerc) Back End cooling tower
Fin Fan coolers The distillation columns overheads are condensed in air-cooled fin fan coolers The advantage of these coolers over water-cooled coolers is low operating cost
Safety measures taken in LAB Plant
1) Safety Interlocks for tripping the operation of equipments in case process variables touches maximum allowable value
2) Flare system for burning excess gases from process3) Infra red detection system for Pacol Reactor and Hot pumps 4) Hydrocarbon detection system for detecting hydrocarbon leakages5) H2S detection system and siren for detecting H2S gas leakages 6) HF Detection system for detecting HF leakages7) Schedule HF leak testing of HF flanges8) Application of HF detection paints to all HF flanges to detect HF leak by decolouration9) Schedule Thickness survey of pipelines in HF area 10) Fire water sprinkler system for HF vessels Columns and pumps11) Fire water sprinkler system for Hot oil pumps12) Yellow boundary marking of HF area where personal protective equipments (PPErsquos) are
mandatory 13) Personal protective equipments (PPErsquos) for HF area Different types of PVC suits are defined
for different types of jobs ( A B C and D type)14) Separate breathing air reciprocating compressor for breathing air for C and D type PVC
suits in case of eemergency15) KOH scrubbing for venting from all HF equipments so that HF will not release into the
flare16) Daily Benzene monitoring with dragger tubes to detect any Benzene leaks from process17) Close draining system of HF and Benzene
21 of 72
PROJECT ndashI
The project is about developing a ldquoBENZENE-WATER WASHrdquo system to remove the impurities coming with fresh benzene that enters into benzene stripper and effects thefin-fan cooler The project is about developing such a scheme which will remove these impurities before entering the benzene stripper to eliminate the failure of fin-fan cooler
The scheme should also be such that it should not reduce the efficiency of the equipment and should be cost-effective
What is Benzene stripper
The high volatility of water dissolved in hydrocarbons is used in this column to obtain water-free benzene in the column bottoms which also removes any dissolved oxygen or non-condensibles in the benzene or off spec feeds Makeup benzene is fed to the overhead receiver on level control reset by the overhead receiver level controller It is refluxed via the overhead pump on flow control reset by the column bottom level controller and sent to the reaction section by the bottoms pump via the benzene stripper feedbottoms exchanger on flow control which is reset by the benzene column receiver level controller The benzene stripper receiver floats on the flare and is sized big enough to allow enough settling time for the water There is a small nitrogen flow via a conservation vent into the receiver vapor flare to maintain a slight nitrogen purge Water is collected in the boot and drained periodically whenever there is a boot high alarm Maintain a visible benzene water interface in the boot sight glass The benzene at the column bottom normally has a water content of less than 20ppm actually much lower if the column is operated well A moisture analyzer alarm high is provided The heat input to the column is provided by a hot oil reboiler with the hot oil flow controlled Off-spec material from the off-spec tank is normally rerun via the benzene stripper coming into the column receiver
What is the Issue
The benzene stripper column overheads are condensed in air-cooler (fin-fan coolers EC-301)The advantage of using this fin-fan cooler is the low operating cost no space constraint as are not on ground level etc This tube-bundle was failing at a frequency of once in a span of two years Failure analysis study was carried out and found that there are some impurities coming along with fresh benzene which are forming acidic solution after condensing in fin-fan This acidic solution formed was causing the repeated failure of tube-bundle
Water dosing was started upstream of the fin-fan bundle to dissolve out the impurities or to neutralize the acidic solution so that tubes can be saved This practice was started in 2008 Even after this modification the failures and continue and its difficult to analyze that what type of impurities are coming with benzene
22 of 72
So to eliminate this problem a scheme has been plotted to design a benzene scrubbing system This will be basically washing of benzene with DM water to remove the impurities before it enters the benzene stripper
The schematic diagram of this system is shown below
The scheme consists of a static mixture for mixing benzene and water for a particular residence time and at a particular velocity as required A gravity settler is for separating benzene and water on the basis of density difference
23 of 72
STATIC MIXER
This mixing device has no moving parts is simple and its cost can be quite reasonable when compared to mechanical driven mixers Static or motionless mixers are relatively new development and have proven to be effective for many specific and valuable process application It is useful for a wide range of viscosity fluids particularly useful in liquid-liquid mixing and also for some gas-liquid dispersion
The concept of motionless mixers is to achieve a uniform composition and temperature distribution in fluids flowing through the device The concept is build around a stationary rigid element placed in a pipe or cylinder that uses the energy of fluid flowing past to produce the mixing The unit becomes more efficient by adding additional static elements causing the flowing fluid elements to split rearrange recombine and split again to repeat the process lsquoxrsquo times for a uniform or homogeneous flowing stream is produced at discharge
Principle of operation
The static mixer unit is a series of fixed helical elements enclosed within a tubular housing
LIQUID ndash LIQUID SEPARATION(Decanters)
Separation of two liquid phases immiscible or partially miscible liquids is a common requirement in the process industries It is also frequently necessary to separate small quantities of entrained water from process streams The simplest form of equipment used to separate liquid phases is the gravity settling tank the decanter Various proprietary equipment is also used to promote coalescence and improve separation in difficult systems or where emulsions are likely to form Centrifugal separators are also used
Decanters (settlers)
Decanters are used to separate liquids where there is a sufficient difference in density between the liquids for the droplets to settle readily Decanters are essentially tanks which give sufficient residence time for the droplets of the dispersed phase to rise (or settle ) to the interface between the phases and coalesce
In an operating decanter there will be three distinct zones or bands clear heavy liquid separating dispersed liquid (the dispersion zone) and clear light liquid The position of the interface can be controlled with or without the use of instruments by use of a siphon take-off for the heavy liquid
24 of 72
Vertical decanter
The height of the take-off can be determined by making a pressure balance Neglecting friction loss in the pipes the pressure exerted by the combined height of the heavy and light liquid in the vessel must be balanced by the height of the heavy liquid in the take-off leg
(z1-z3)Ρ1g + z3 Ρ2g= z2 Ρ2g
z2 = (z1-z3) Ρ1 + z3 (1)Ρ2
WhereZ1= height from datum to light liquid overflow m Z2=height from datum to heavy liquid overflow m Z3=height from datum to interface m Ρ1=density of the light liquid kgmsup3 Ρ2=density of the heavy liquid kg msup3
The height of the liquid interface should be measured accurately when the liquid densities are close when one component is present only in small quantities or when the throughput is very small A typical scheme for the automatic control of the interface using a level instrument that can detect the position of the interface is shown in the diagram below Where one phase is present only in small amounts it is often recycled to the decanter feed to give more stable operation
25 of 72
CALCULATIONS
STATIC MIXER DESIGN
Required data
1 Physical properties of materials Density kgmsup3
Viscosity Pas = 0001Cp
2 Pressure drop Pressure drop in static mixer is best described by comparison with pipe flow
3 Geometrical parameters Diameter m
Type of static mixer constant (k)
Length (l) m
4 Process variables
Flow rate msup3s TemperaturedegC Pressure bar
26 of 72
Pressure drop calculation
a) Velocity (v)
V = Qπ4 Dsup2
b) Reynoldsrsquos number(Re)
Re= dvρμ
c) Pressure drop (Δp)For Re lt50 Δp =k1x μ x l xQd dsup3
k1= laminar flow constant
For Re gt10sup3 Δp =k2 x ρ x l x vsup2d 2
= k2 x Q x l x 8 x Qsup2d prodsup2 d⁴
k2= turbulent flow constant
Pipe diameter Flow seems to be turbulent as both the materials (B2+ H2O) are not viscous
D =39Q ⁰ ⁴⁵ ρ sup1sup3⁰
Q =52 + 572 = 1092msup3hr = 303 x 10macrsup3msup3s= 38564 ftsup3hr
Ρ = 926328 kgmsup3 =57828 lbftsup3
D =39 x Q ⁰ ⁴⁵ x ρ sup1sup3⁰
D =39 x (38564) ⁰ ⁴⁵ x (57828) sup1sup3⁰ 3600
D= 24 inch = 25 inch = 00635m
27 of 72
Velocity(v)
V =4 Q proddsup2
= 303 x 10macrsup3 msup3s x 4 314 x (00635)sup2
= 0957 ms (approx 1ms)
Reynoldrsquosnumber(Re)
Re = dvρ Μ = 00635 x 1 x 926328 0572
Re =103 x 10⁵
Thus the flow is highly turbulent
Flow regime Reynoldrsquos no(Re)
No of element No of elements to add if viscosity ratio between fluids exceeds 10001
No of elements to add if volumetric ratio between fluids exceeds 1001
Laminar lt1 24 6 61-10 18 6 611-50 14 6 651-100 12 6 6101-500 10 6 6
Transitional 501-1000 8 4 41001-2000 6 4 4
Turbulent 2001-5000 4 2 25001+ 2 2 2
Thus from the above table the mixer will have 2 elements
The mixer length will be based on the number of elements required An approximate length can be determined by multiplying the number of elements by 15
Mixer length = 15 x 2 =3
28 of 72
For turbulent flow applications it is generally recommended that a minimum velocity of 10 ftsec be maintained
V= 0408 x QDsup2 = 0408 x 4813sup2 = 218 ftsec =066 ms
DECANTER DESIGN
Benzene Water
Flow rate (msup3h) 52 572
Flow rate (kgh) 4543812 570311
Density (kgmsup3) 87381 99704
Viscosity (Pas) 0000604 000089
Take Dd = 150microm
microd = (150 Х 10ˉ⁶)sup2 Х 981 Х (87381-99704) 18 Х 000089
microd = -169787 Х 10ˉsup3 ms = -17 mms (rising)
As the flow rate is small we will use a vertical cylindrical vessel
The decanter vessel is sized on the basis that the velocity of the continuous phase must be less than settling velocity of the droplets of the dispersed phase Plug flow is assumed and the velocity of the continuous phase calculated using the area of the interfacemicroc =Lclt microdAiWhere microd = settling velocity of the dispersed phase droplets msmicroc = velocity of the continuous phase msLc = continuous phase volumetric flow rate msup3sAi = area of the interface msup2
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Lc = 570311 X 1 99704 3600
= 00015889 msup3s
Ai=Lc = 00015889 microc 00017
= 0935817588 msup2
For a vertical cylindrical decanterAi = prodrsup2
r = 0935817588 prodr = 0545835318 m
Diameter= 1091670637 m
Taking the height as twice the diameter a reasonable value for a cylinder
Height = 2183341274 m
The position of the interface should be such that the band of droplets that collect at the interface waiting to coalesce and cross the interface does not extend to the bottom (or top) of the vessel The depth of the dispersion band is a function of the liquid flow rate and the interfacial area A value of to per cent of the decanter height is usually taken for the design purposes
Take the dispersion band as 10 per cent of the height = 021833mThe residence time of the droplets in the dispersion band = 021833 = 021833microd 00017 =1285926 s (approx 2 min)
This is satisfactory time a time of 2 to 5 min is normally recommended Thus the size of the water (continuous heavy phase) droplets that could be entrained with benzene (light phase) will be
Velocity of benzene phase = 4543812 X 1 X 1 873811 3600093581
=0001543511 ms =1543511mms
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So from equation ( ) So the entrained droplet size will be =00015435 X 18 X 0000604 frac12 981 X (99704-873812)
=00001178 m=1178 microm
which is satisfactory below 150 microm
Piping arrangement
To minimize entrainment by the jet of liquid entering the vessel the inlet velocity for a decanter should keep below 1 ms
The velocity from static mixer= 066 ms
Flow rate= 4543812 + 570311 X 1 87381 99704 3600
= 0003033345msup3s
Area of pipe= flow ratevelocity
= 0003033345066
= 0004554572msup2
Pipe diameter =0004554572 x 4prod
= 0076158749 m =29983 inch (approx 3 in)
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PROJECT II
CALULATING THE DEW POINT
This project is about the study and evaluation of the performance of the compressors in the Hydrobon section of the LAB plant which is installed to optimize the purity of hydrogen coming from the product separators The compressors in this section include recycle gas compressor and make-up gas compressorThe purity of hydrogen can be increased upto 90
This project will give the company an overall view of this loop The plant is running well about its installed capacity(131-140) The company wants to retain the purity level of nearly 90 for hydrogen even after operating above installed capacity Hence the current project will give the company an idea of the current hydrogen quality(purity) which is obtained and give an idea about changes if any to be made to existing process set-up
HYDROBON REACTOR
Hydrobon reactor is designed to remove contaminants present in the raw kerosene without changing the boiling range The hydrocarbon is passed through a 2 bed reactor feed with S 12 catalyst through a feed effluent exchanger and charge heater which maintain the required reaction temperature(310 c) The reaction required hydrogen gas which is supplied from pacol net gas generated from back end and tattoray hydrogen from PX plantThe reaction charge is heated to the reaction temperature in the charge heater enters the reactor from the top and is distributed over the catalyst bed Catalytic hydrogenation takes place in the reactor The impurities react with hydrogen and form salts which are subsequently separated and finally removed in sour water stripper The reactor effluents after separation is fed to the product stripper to remove lighters and hydrotreated kerosene is fed to molex unit The sulfur and nitrogen levels are reduced to 1 ppm or less
PARAMETERS DESIGN ACTUALPlant load() 100 115Hydrobon feed rate(mthr) 58 60Temperature 416 310Pressure (kgcm2 g) 822 62H2HC ratio 385 460Recycle hydrogen purity(mole)
75 min 95
Hydrobon feed specificationa Bromine
index(mg100gm)800 800
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b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
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HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
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4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
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FLOW DIAGRAM OF HYDROBON SECTION
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Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
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nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
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Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
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DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
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ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
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Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
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Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
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Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
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=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
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Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
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Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
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Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
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Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
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Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
OBJECTIVES
The objectives of the training were
To understand the modern technologies applied for designing a chemical process plant
To develop an understanding of the working environment of the chemical industry
To build on the knowledge gathered in the college and understand its practical application
To get an insight to the modern chemical industry in the developing Indian economy
4 of 72
INDEX
Srno ContentsPROJECT-1
1 Introduction 2 Study of LAB process3 Alkylation unit4 Developed scheme5 Scheme description6 Calculation 7 Specification sheets
PROJECT-28 Introduction 9 Dew point10 Performance Evaluation of GB-601 AB11 Flash calculation for 1st stage12 Performance Evaluation of GB-602 ABC13 Flash calculation for 1st stage14 Flash calculation for 2nd stage15 Flash calculation for 3rd stage16 Flash calculation for 4th stage17 Safety measures in LAB plant
5 of 72
COMPANY INFORMATION
Reliance Industries Limited found by Dhirubhai H Ambani is Indiarsquos largest private sector enterprise with businesses in the energy and materials value chain Grouprsquos annual revenues are in excess of US$ 28 billion The flagship company of RIL is a Fortune Global 500 company and its largest private sector company in India
Backward vertical integration has been the cornerstone of the evolution and growth of Reliance Starting with textiles in the late seventies Reliance pursued a strategy of backward vertical integration in polyesters fibre intermediates plastics petrochemicals petroleum refining and oil and gas exploration and production ndash to be fully integrated along the materials and energy value chain
Reliance enjoys global leadership in its businesses being the largest polyester yarn and fibre producer in the world and among the top ten producers in the world in major petrochemical products
Major Group Companies are Reliance Industries Limited (including main subsidiary Reliance Retail Limted ) and Reliance Industrial Infrastructure Limited
6 of 72
LAB (Linear Alkyl Benzene) Process Overview
Introduction
The linear alkylbenzenes produced from C10-C13 linear olefins are useful detergent intermediates and can be readily sulfonated to yield linear alkylbenzensulfonates
HF acid catalystC10C13 olefins + Benzene Linear alkyl benzene (LAB)
SulfonationLinear Alkyl benzene (LAB) LAB sulfonates
These compounds constitute the ldquoactiverdquo ingredients of many household detergents They are surface-active compounds (surfactants) which are combined with various builders (often inorganic salts) to make up a detergent formula
BuildersLAB sulfonates House hold Detergents
Typical Detergent formulation
LAB sulfonates 25wt
Sodium tripolyphosphate 40 wt
Sodium silicate 10 wt
Sodium sulfate 16 wt
Water 8 wt
Carboxymethylcellulose 1 wt
7 of 72
History
During 1940rsquos and 1950rsquos the detergent market was primarily captured by dodecylbenzene (DDB) a product formed by alkylation of Benzene with propylene tetramer It was found that detergent formed by this was giving poor biodegradability of detergent
Propylene tetramer + Benzene Dodecylbenzene (DDB) (Low biodegradability)
Thus LAB introduced in early 60rsquos have substantially replaced this DDB which is having good biodegradability (gt95)
Process Description
Brief Overview
LAB manufacturing process is a technology patented by UOP Inc (Universal oil Product)
The LAB plant is divided into two parts called
a) Front Endb) Back End
In Front End Normal paraffin which is raw material for LAB is extracted from kerosene feed (UOP Molex unit)
UOP Molex unit Feed kerosene N paraffin (C10- C13) (Normal amp (Raw material for LAB) Non-normal paraffin)
8 of 72
In Back End this Normal paraffin is dehydrogenated to linear olefins (UOP Pacol unit)The linear olefins are then alkylated with benzene to LAB
UOP Pacol unit(Dehydrogenation)N paraffin (C10- C13) Linear Olefins (C10-C13)
HF acid catalystC10C13 olefins + Benzene Linear alkyl benzene (LAB)
Detail Description of Process
1) Front EndAs described earlier Normal paraffin (C10 to C13) is extracted from kerosene feed by UOP molex process The kerosene feed stock contains various carbon-chained compounds ranging from C7 to C17 This kerosene is processed in front end in series of processes they are
a) Prefractionation b) Hydrobon c) Molex
a) PREFRACTIONATION
The kerosene is fed to Prefractionation unit where heart cut kerosene of carbon chain C 10 to C14
is separated in two distillation columns in series
1) Stripper column
In this distillation column lighter compounds less than C10 are separated from top as
distillate The bottoms from the column is fed to second distillation column called
Rerun column
2) Rerun columnIn this column Heart cut kerosene of C10 to C14 is separated from top as distillate
9 of 72
STRIPPER
RERUN
Heart cut Kerosene (C10 to C14)
Light Kerosene
Feed kerosene
Heavy kerosene
b) HYDROBON
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit The catalyst used in Hydrobon reactor is S12 (Nickel ndashmolybdenumumoxide on alumina)
The heartcut kerosene from Prefractionation rerun column overhead is fed to this Hydrobon unit to remove sulfur nitrogen below 1 ppm This reaction is called as hydrotreating In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor
10 of 72
C-C-C-C-SH + H2 C-C-C-C + H2SOrganic sulfur(Mercaptan)
+ H2 C-C-C-C-C + NH3 N Nitrogen compound (Pyridine)
The reaction temperature is maintained at 310DegC while pressure is maintained at 65kgcm2g
The reactor temperature is maintained by charge heater where heat input is given by firing fuel
oil A recycle gas compressor and makeup gas compressor maintains the reactor pressure to 65
kgcm2g The H2 required for reaction is compressed in makeup gas compressor upto reactor
pressure
At reaction temperature cracking also takes place where some lighter (ltC10) are formed To
separate this the reactor effluent is passed to distillation column called Product Stripper The off
gases separated in stripper are burnt in heater as fuel
The H2S and NH3 formed in reaction form the ammonium sulfide salts The water is injected in
reactor effluent to prevent the deposition of salts that can corrode and foul the coolers The
desolved salts in water are further treated in sour water stripper to separate H2S and NH3 which
are burnt in heater as off gas
11 of 72
ProductSeparator
PRODUCT
STR
Lighters andOff gases
H2 from makeup gas compressor
Hydrobon reactor
To Molex unit
Charge heater
Feed from Prefractionation
Block Diagram of Hydrobon unit
c) MOLEX Molex process is effective method of separating normal paraffin from stream of hydrocarbon having normal and non-normal by physical selective adsorption process
The process uses solid adsorbent (Molecular sieve) where normal paraffin of straight chains are adsorbed in selective pores and non normal of branched chain are adsorbed in non selective pores
The adsorbed normal paraffin are then desorbed by normal pentane while non normal are desorbed by iso-octane
12 of 72
CHAMBER
CHAMBER
ROTARY VALVE
EXTRACT
RAFFINATE
Normal paraffin Non Normal
There are two adsorption chambers with 24 beds The process simulates countercurrent contact between fixed bed adsorbent and feed stream This simulation is done by flow directing device called ldquoRotary valverdquo
The separated streams from Molex chambers containing normal paraffin (Extract) and non normal (Raffinate) are fed to two distillation columns a) Extract column and b) Raffinate column In both distillation columns desorbent is separated from top and sidecut and recycled for desorption While bottom product of Extract column is Normal paraffin send to storage
E R
F
D
13 of 72
STRIPPER
RERUN
Heart cut Paraffin (C10 to C13)
Light NP
Feed NP
Heavy NP
2) Back EndAs described earlier Linear alkyl benzene (LAB) is produced from linear olefins by UOP detergent alkylation process The raw material normal paraffin of C10 to C14 from front end is processed in back end in series of processes they are
a) Prefractionation b) Pacol c) Alkylation
a) PREFRACTIONATION The normal paraffin of C10 to C14 carbon range is separated to Normal paraffin of C10 to C13 carbon range in two distillation columns in series
1) Stripper column In this distillation column lighter compound (if any) and partly C10 paraffin is removed as light normal paraffin (LNP) from top This LNP is sold in market as byproduct The bottoms is send to Rerun column
2) Rerun ColumnIn this column heartcut paraffin (C10 to C13) is separated from top as distillate The bottoms containing mainly C14 paraffin is sold in market as heavy normal paraffin (HNP) as byproduct
14 of 72
b) PACOL (Paraffin converted to olefin)
The normal paraffin of carbon range C10 to C13 is converted to linear olefins of carbon range C10 to C13 by Dehydrogenation reaction in UOP Pacol process
The catalyst used in reactor is alumina based platinum catalyst
Platinum catalyst
CH3-C-C-C-CH3 CH3 - C = C ndash C ndash CH3 + H2
N paraffin Linear Mono olefins
There are some side reactions takes places in Pacol they are
CH3 - C = C ndash C ndash CH3 CH3 - C = C = C ndash CH3 + H2
Linear Mono olefins Linear Di olefins
CH3 - C = C = C ndash CH3 Aromatics + H2
Linear Di olefins
As it is dehydrogenation reaction H2 gas is separated from reactor effluent in contact condenser and send to Front End for Hydrobon makeup gas compressor
Cracking also takes place in reactor where ltC10 paraffin and olefins are formed which is removed in distillation column called Pacol stripper The gas separated in stripper is burnt in heater as off gases
The reaction temperature is 470 to 495 DegC while pressure is kept low at 13 kgcm2g
The life of pacol catalyst is about 30 to 40 days As life of the catalyst is low there are two pacol reactors for continuous running of the plant
The conversion of paraffin is about 12 to 13
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ContactCondenser
PACOL
STPR
Lighters andOff gases
Pacol reactor
To Alkylation
Charge heater
Normal ParaffinFeed
H2 to front end
DEFINE UNIT
The main purpose of this unit is to increase overall yield of LAB The Diolefins formed in Pacol reaction is converted to Mono olefins and normal paraffin thereby generating more LAB and lesser byproducts
The catalyst used in this reactor is Nickel based on alumina
Nickel catalyst
Diolefins + H2 Mono olefins
Diolefins + H2 Normal Paraffin
The reaction temperature is 180 DegC and pressure is 140 Kgcm2g
Block Diagram of Pacol Unit
16 of 72
IMIXER
2MIXER
HFSTRIPPER
C) ALKYLATION
As described earlier linear olefins (C10 to C13) are alkylated in this unit to form Linear alkyl Benzene (LAB) in presence of HF acid catalyst
The mono olefins are conveterd to Linear alkyl benzene (LAB) while diolefins are conveterd to Heavy alkyl Benzene (HAB) The aromatics are extracted in counter current extraction of HF acid and are separated in distillation column called Acid regenerators
HF acid catalyst
R- CH = CH ndashCH2 ndash Rrsquo + Benzene R-CH-CH2-CH2-Rrsquo
M Olefins
Where R and Rrsquo are alkyl groups (CH3) LAB
R-CH=CH-CH=CH-Rrsquo + 2 Benzene Heavy alkyl benzene
Di olefins HAB
The reaction is instantaneous and carried through a two stage mixer settler system The reactor section effluent is then processed in series of distillation columns where excess Benzene Paraffin LAB and byproduct Heavy alkyl benzene (HAB) gets separated
The separated benzene is recycled back to HF alkylation reactor while separated Paraffin is recycled to Pacol reactor for reaction The product Linear alkyl benzene (LAB) and byproduct Heavy alkyl benzene (HAB) are send to storage
The aromatics and non-normal which are formed in Pacol reaction are extracted in HF reaction unit by counter current extraction of HF acid as POLYMER This polymer is separated in Acid regenerators and then neutralized with KOH and send to storage
Block Diagram of Alkylation process
17 of 72
PROCESS INPUTS amp OUTPUTS
18 of 72
As described earlier plant is divided into two sections
a) Front End for Normal paraffin production from Keroseneb) Back End for Linear alkyl Benzene (LAB) production from N paraffin
The raw material kerosene is supplied to the plant from two sources
a) From Bharat Petroleum Corp Ltd Chembur (BPCL) via 55 Km pipelineb) From Reliance Petroleum Ltd Jamnagar via Shipping
The light kerosene heavy kerosene and Raffinate from front end are combined and send as return kerosene via pipeline or shipping to either BPCL or to RPL Jamnagar
The manufacturing of LAB is done in two grades
a) Domestic grade (Molecular weight 235 to 239)b) Export grade (Molecular weight 239 to 240)
The byproducts of LAB plant are
a) Light Normal paraffinb) Heavy normal paraffinc) Heavy alkyl Benzened) Tar polymer
Installed Capacities
A) For Normal Paraffin 115000 MT Highest prod 126596 MT in year 2001-2002
B) For LAB 100000 MT Highest prod 112484 MT in year 1999-2000
Plant load
A) For Normal Paraffin 117
B) For LAB 120 Production per day
A) For Normal Paraffin 330 MT day (Avrg)
B) For LAB 324 MTday (Avrg)
Customers
19 of 72
1) The Normal paraffin produced in LAB plant is normally used for captive consumption for producing LAB
2) The main customer of LAB is Ms Hindustan Lever and Procter amp Gamble Ltd and their subsidiary
3) The LAB is exported to Europe American African and Asian countries4) The light and Heavy normal paraffin is used to manufacture Chlorinated Paraffin Wax5) Heavy alkyl Benzene is used as lubricants in oil industry
Utility system in LAB plant
Hot oil system
There are two Hot oil Heaters available in LAB plant one for Front End and other is for Back End The Heaters are fired with furnace oil LSHS and off gases from process
The Hot oil (Dow Therm) which is thermic fluid is heated in these Hot oil heaters
The all heat inputs to the column preheater are given by circulating Hot oil at supply temperature of 330 DegC
Effluent System
The effluent generated in LAB plant mainly constitute
a) Fluoride Maximum limit lt 10 ppmb) Oil Maximum limit lt 10 ppm
For reduction of fluoride in effluent water LAB plant have two neutralisation basins where effluent from HF area is collected and then reacted with Lime (CaCO3) to reduce fluoride content below 10ppm
For reduction of oil in effluent water LAB plant have CPI separator installed to separate oil from effluent water The oil separated is send to Slope oil storage
In addition to this there is hydrocarbon pit installed in front end to collect pump and filter drains which is being blended in return kerosene to reduce oil load in effluent systemThere all oil collection pits installed in storm water channels to avoid oil going into the river via gates
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Cooling water systemFor cooling the final products Byproducts to normal ambient temperatures the products byproducts are cooled in coolers The cooling media used is water There are three cooling towers installed in LAB planta) HF cooling tower it is separate cooling tower to avoid HF ingrace in coolers in non-HF
areab) Front End Cooling towerc) Back End cooling tower
Fin Fan coolers The distillation columns overheads are condensed in air-cooled fin fan coolers The advantage of these coolers over water-cooled coolers is low operating cost
Safety measures taken in LAB Plant
1) Safety Interlocks for tripping the operation of equipments in case process variables touches maximum allowable value
2) Flare system for burning excess gases from process3) Infra red detection system for Pacol Reactor and Hot pumps 4) Hydrocarbon detection system for detecting hydrocarbon leakages5) H2S detection system and siren for detecting H2S gas leakages 6) HF Detection system for detecting HF leakages7) Schedule HF leak testing of HF flanges8) Application of HF detection paints to all HF flanges to detect HF leak by decolouration9) Schedule Thickness survey of pipelines in HF area 10) Fire water sprinkler system for HF vessels Columns and pumps11) Fire water sprinkler system for Hot oil pumps12) Yellow boundary marking of HF area where personal protective equipments (PPErsquos) are
mandatory 13) Personal protective equipments (PPErsquos) for HF area Different types of PVC suits are defined
for different types of jobs ( A B C and D type)14) Separate breathing air reciprocating compressor for breathing air for C and D type PVC
suits in case of eemergency15) KOH scrubbing for venting from all HF equipments so that HF will not release into the
flare16) Daily Benzene monitoring with dragger tubes to detect any Benzene leaks from process17) Close draining system of HF and Benzene
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PROJECT ndashI
The project is about developing a ldquoBENZENE-WATER WASHrdquo system to remove the impurities coming with fresh benzene that enters into benzene stripper and effects thefin-fan cooler The project is about developing such a scheme which will remove these impurities before entering the benzene stripper to eliminate the failure of fin-fan cooler
The scheme should also be such that it should not reduce the efficiency of the equipment and should be cost-effective
What is Benzene stripper
The high volatility of water dissolved in hydrocarbons is used in this column to obtain water-free benzene in the column bottoms which also removes any dissolved oxygen or non-condensibles in the benzene or off spec feeds Makeup benzene is fed to the overhead receiver on level control reset by the overhead receiver level controller It is refluxed via the overhead pump on flow control reset by the column bottom level controller and sent to the reaction section by the bottoms pump via the benzene stripper feedbottoms exchanger on flow control which is reset by the benzene column receiver level controller The benzene stripper receiver floats on the flare and is sized big enough to allow enough settling time for the water There is a small nitrogen flow via a conservation vent into the receiver vapor flare to maintain a slight nitrogen purge Water is collected in the boot and drained periodically whenever there is a boot high alarm Maintain a visible benzene water interface in the boot sight glass The benzene at the column bottom normally has a water content of less than 20ppm actually much lower if the column is operated well A moisture analyzer alarm high is provided The heat input to the column is provided by a hot oil reboiler with the hot oil flow controlled Off-spec material from the off-spec tank is normally rerun via the benzene stripper coming into the column receiver
What is the Issue
The benzene stripper column overheads are condensed in air-cooler (fin-fan coolers EC-301)The advantage of using this fin-fan cooler is the low operating cost no space constraint as are not on ground level etc This tube-bundle was failing at a frequency of once in a span of two years Failure analysis study was carried out and found that there are some impurities coming along with fresh benzene which are forming acidic solution after condensing in fin-fan This acidic solution formed was causing the repeated failure of tube-bundle
Water dosing was started upstream of the fin-fan bundle to dissolve out the impurities or to neutralize the acidic solution so that tubes can be saved This practice was started in 2008 Even after this modification the failures and continue and its difficult to analyze that what type of impurities are coming with benzene
22 of 72
So to eliminate this problem a scheme has been plotted to design a benzene scrubbing system This will be basically washing of benzene with DM water to remove the impurities before it enters the benzene stripper
The schematic diagram of this system is shown below
The scheme consists of a static mixture for mixing benzene and water for a particular residence time and at a particular velocity as required A gravity settler is for separating benzene and water on the basis of density difference
23 of 72
STATIC MIXER
This mixing device has no moving parts is simple and its cost can be quite reasonable when compared to mechanical driven mixers Static or motionless mixers are relatively new development and have proven to be effective for many specific and valuable process application It is useful for a wide range of viscosity fluids particularly useful in liquid-liquid mixing and also for some gas-liquid dispersion
The concept of motionless mixers is to achieve a uniform composition and temperature distribution in fluids flowing through the device The concept is build around a stationary rigid element placed in a pipe or cylinder that uses the energy of fluid flowing past to produce the mixing The unit becomes more efficient by adding additional static elements causing the flowing fluid elements to split rearrange recombine and split again to repeat the process lsquoxrsquo times for a uniform or homogeneous flowing stream is produced at discharge
Principle of operation
The static mixer unit is a series of fixed helical elements enclosed within a tubular housing
LIQUID ndash LIQUID SEPARATION(Decanters)
Separation of two liquid phases immiscible or partially miscible liquids is a common requirement in the process industries It is also frequently necessary to separate small quantities of entrained water from process streams The simplest form of equipment used to separate liquid phases is the gravity settling tank the decanter Various proprietary equipment is also used to promote coalescence and improve separation in difficult systems or where emulsions are likely to form Centrifugal separators are also used
Decanters (settlers)
Decanters are used to separate liquids where there is a sufficient difference in density between the liquids for the droplets to settle readily Decanters are essentially tanks which give sufficient residence time for the droplets of the dispersed phase to rise (or settle ) to the interface between the phases and coalesce
In an operating decanter there will be three distinct zones or bands clear heavy liquid separating dispersed liquid (the dispersion zone) and clear light liquid The position of the interface can be controlled with or without the use of instruments by use of a siphon take-off for the heavy liquid
24 of 72
Vertical decanter
The height of the take-off can be determined by making a pressure balance Neglecting friction loss in the pipes the pressure exerted by the combined height of the heavy and light liquid in the vessel must be balanced by the height of the heavy liquid in the take-off leg
(z1-z3)Ρ1g + z3 Ρ2g= z2 Ρ2g
z2 = (z1-z3) Ρ1 + z3 (1)Ρ2
WhereZ1= height from datum to light liquid overflow m Z2=height from datum to heavy liquid overflow m Z3=height from datum to interface m Ρ1=density of the light liquid kgmsup3 Ρ2=density of the heavy liquid kg msup3
The height of the liquid interface should be measured accurately when the liquid densities are close when one component is present only in small quantities or when the throughput is very small A typical scheme for the automatic control of the interface using a level instrument that can detect the position of the interface is shown in the diagram below Where one phase is present only in small amounts it is often recycled to the decanter feed to give more stable operation
25 of 72
CALCULATIONS
STATIC MIXER DESIGN
Required data
1 Physical properties of materials Density kgmsup3
Viscosity Pas = 0001Cp
2 Pressure drop Pressure drop in static mixer is best described by comparison with pipe flow
3 Geometrical parameters Diameter m
Type of static mixer constant (k)
Length (l) m
4 Process variables
Flow rate msup3s TemperaturedegC Pressure bar
26 of 72
Pressure drop calculation
a) Velocity (v)
V = Qπ4 Dsup2
b) Reynoldsrsquos number(Re)
Re= dvρμ
c) Pressure drop (Δp)For Re lt50 Δp =k1x μ x l xQd dsup3
k1= laminar flow constant
For Re gt10sup3 Δp =k2 x ρ x l x vsup2d 2
= k2 x Q x l x 8 x Qsup2d prodsup2 d⁴
k2= turbulent flow constant
Pipe diameter Flow seems to be turbulent as both the materials (B2+ H2O) are not viscous
D =39Q ⁰ ⁴⁵ ρ sup1sup3⁰
Q =52 + 572 = 1092msup3hr = 303 x 10macrsup3msup3s= 38564 ftsup3hr
Ρ = 926328 kgmsup3 =57828 lbftsup3
D =39 x Q ⁰ ⁴⁵ x ρ sup1sup3⁰
D =39 x (38564) ⁰ ⁴⁵ x (57828) sup1sup3⁰ 3600
D= 24 inch = 25 inch = 00635m
27 of 72
Velocity(v)
V =4 Q proddsup2
= 303 x 10macrsup3 msup3s x 4 314 x (00635)sup2
= 0957 ms (approx 1ms)
Reynoldrsquosnumber(Re)
Re = dvρ Μ = 00635 x 1 x 926328 0572
Re =103 x 10⁵
Thus the flow is highly turbulent
Flow regime Reynoldrsquos no(Re)
No of element No of elements to add if viscosity ratio between fluids exceeds 10001
No of elements to add if volumetric ratio between fluids exceeds 1001
Laminar lt1 24 6 61-10 18 6 611-50 14 6 651-100 12 6 6101-500 10 6 6
Transitional 501-1000 8 4 41001-2000 6 4 4
Turbulent 2001-5000 4 2 25001+ 2 2 2
Thus from the above table the mixer will have 2 elements
The mixer length will be based on the number of elements required An approximate length can be determined by multiplying the number of elements by 15
Mixer length = 15 x 2 =3
28 of 72
For turbulent flow applications it is generally recommended that a minimum velocity of 10 ftsec be maintained
V= 0408 x QDsup2 = 0408 x 4813sup2 = 218 ftsec =066 ms
DECANTER DESIGN
Benzene Water
Flow rate (msup3h) 52 572
Flow rate (kgh) 4543812 570311
Density (kgmsup3) 87381 99704
Viscosity (Pas) 0000604 000089
Take Dd = 150microm
microd = (150 Х 10ˉ⁶)sup2 Х 981 Х (87381-99704) 18 Х 000089
microd = -169787 Х 10ˉsup3 ms = -17 mms (rising)
As the flow rate is small we will use a vertical cylindrical vessel
The decanter vessel is sized on the basis that the velocity of the continuous phase must be less than settling velocity of the droplets of the dispersed phase Plug flow is assumed and the velocity of the continuous phase calculated using the area of the interfacemicroc =Lclt microdAiWhere microd = settling velocity of the dispersed phase droplets msmicroc = velocity of the continuous phase msLc = continuous phase volumetric flow rate msup3sAi = area of the interface msup2
29 of 72
Lc = 570311 X 1 99704 3600
= 00015889 msup3s
Ai=Lc = 00015889 microc 00017
= 0935817588 msup2
For a vertical cylindrical decanterAi = prodrsup2
r = 0935817588 prodr = 0545835318 m
Diameter= 1091670637 m
Taking the height as twice the diameter a reasonable value for a cylinder
Height = 2183341274 m
The position of the interface should be such that the band of droplets that collect at the interface waiting to coalesce and cross the interface does not extend to the bottom (or top) of the vessel The depth of the dispersion band is a function of the liquid flow rate and the interfacial area A value of to per cent of the decanter height is usually taken for the design purposes
Take the dispersion band as 10 per cent of the height = 021833mThe residence time of the droplets in the dispersion band = 021833 = 021833microd 00017 =1285926 s (approx 2 min)
This is satisfactory time a time of 2 to 5 min is normally recommended Thus the size of the water (continuous heavy phase) droplets that could be entrained with benzene (light phase) will be
Velocity of benzene phase = 4543812 X 1 X 1 873811 3600093581
=0001543511 ms =1543511mms
30 of 72
So from equation ( ) So the entrained droplet size will be =00015435 X 18 X 0000604 frac12 981 X (99704-873812)
=00001178 m=1178 microm
which is satisfactory below 150 microm
Piping arrangement
To minimize entrainment by the jet of liquid entering the vessel the inlet velocity for a decanter should keep below 1 ms
The velocity from static mixer= 066 ms
Flow rate= 4543812 + 570311 X 1 87381 99704 3600
= 0003033345msup3s
Area of pipe= flow ratevelocity
= 0003033345066
= 0004554572msup2
Pipe diameter =0004554572 x 4prod
= 0076158749 m =29983 inch (approx 3 in)
31 of 72
32 of 72
33 of 72
34 of 72
35 of 72
36 of 72
37 of 72
PROJECT II
CALULATING THE DEW POINT
This project is about the study and evaluation of the performance of the compressors in the Hydrobon section of the LAB plant which is installed to optimize the purity of hydrogen coming from the product separators The compressors in this section include recycle gas compressor and make-up gas compressorThe purity of hydrogen can be increased upto 90
This project will give the company an overall view of this loop The plant is running well about its installed capacity(131-140) The company wants to retain the purity level of nearly 90 for hydrogen even after operating above installed capacity Hence the current project will give the company an idea of the current hydrogen quality(purity) which is obtained and give an idea about changes if any to be made to existing process set-up
HYDROBON REACTOR
Hydrobon reactor is designed to remove contaminants present in the raw kerosene without changing the boiling range The hydrocarbon is passed through a 2 bed reactor feed with S 12 catalyst through a feed effluent exchanger and charge heater which maintain the required reaction temperature(310 c) The reaction required hydrogen gas which is supplied from pacol net gas generated from back end and tattoray hydrogen from PX plantThe reaction charge is heated to the reaction temperature in the charge heater enters the reactor from the top and is distributed over the catalyst bed Catalytic hydrogenation takes place in the reactor The impurities react with hydrogen and form salts which are subsequently separated and finally removed in sour water stripper The reactor effluents after separation is fed to the product stripper to remove lighters and hydrotreated kerosene is fed to molex unit The sulfur and nitrogen levels are reduced to 1 ppm or less
PARAMETERS DESIGN ACTUALPlant load() 100 115Hydrobon feed rate(mthr) 58 60Temperature 416 310Pressure (kgcm2 g) 822 62H2HC ratio 385 460Recycle hydrogen purity(mole)
75 min 95
Hydrobon feed specificationa Bromine
index(mg100gm)800 800
38 of 72
b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
39 of 72
HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
40 of 72
4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
41 of 72
FLOW DIAGRAM OF HYDROBON SECTION
42 of 72
Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
43 of 72
nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
44 of 72
Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
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DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
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ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
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Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
49 of 72
Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
50 of 72
Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
51 of 72
=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
52 of 72
Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
53 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
54 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
55 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
INDEX
Srno ContentsPROJECT-1
1 Introduction 2 Study of LAB process3 Alkylation unit4 Developed scheme5 Scheme description6 Calculation 7 Specification sheets
PROJECT-28 Introduction 9 Dew point10 Performance Evaluation of GB-601 AB11 Flash calculation for 1st stage12 Performance Evaluation of GB-602 ABC13 Flash calculation for 1st stage14 Flash calculation for 2nd stage15 Flash calculation for 3rd stage16 Flash calculation for 4th stage17 Safety measures in LAB plant
5 of 72
COMPANY INFORMATION
Reliance Industries Limited found by Dhirubhai H Ambani is Indiarsquos largest private sector enterprise with businesses in the energy and materials value chain Grouprsquos annual revenues are in excess of US$ 28 billion The flagship company of RIL is a Fortune Global 500 company and its largest private sector company in India
Backward vertical integration has been the cornerstone of the evolution and growth of Reliance Starting with textiles in the late seventies Reliance pursued a strategy of backward vertical integration in polyesters fibre intermediates plastics petrochemicals petroleum refining and oil and gas exploration and production ndash to be fully integrated along the materials and energy value chain
Reliance enjoys global leadership in its businesses being the largest polyester yarn and fibre producer in the world and among the top ten producers in the world in major petrochemical products
Major Group Companies are Reliance Industries Limited (including main subsidiary Reliance Retail Limted ) and Reliance Industrial Infrastructure Limited
6 of 72
LAB (Linear Alkyl Benzene) Process Overview
Introduction
The linear alkylbenzenes produced from C10-C13 linear olefins are useful detergent intermediates and can be readily sulfonated to yield linear alkylbenzensulfonates
HF acid catalystC10C13 olefins + Benzene Linear alkyl benzene (LAB)
SulfonationLinear Alkyl benzene (LAB) LAB sulfonates
These compounds constitute the ldquoactiverdquo ingredients of many household detergents They are surface-active compounds (surfactants) which are combined with various builders (often inorganic salts) to make up a detergent formula
BuildersLAB sulfonates House hold Detergents
Typical Detergent formulation
LAB sulfonates 25wt
Sodium tripolyphosphate 40 wt
Sodium silicate 10 wt
Sodium sulfate 16 wt
Water 8 wt
Carboxymethylcellulose 1 wt
7 of 72
History
During 1940rsquos and 1950rsquos the detergent market was primarily captured by dodecylbenzene (DDB) a product formed by alkylation of Benzene with propylene tetramer It was found that detergent formed by this was giving poor biodegradability of detergent
Propylene tetramer + Benzene Dodecylbenzene (DDB) (Low biodegradability)
Thus LAB introduced in early 60rsquos have substantially replaced this DDB which is having good biodegradability (gt95)
Process Description
Brief Overview
LAB manufacturing process is a technology patented by UOP Inc (Universal oil Product)
The LAB plant is divided into two parts called
a) Front Endb) Back End
In Front End Normal paraffin which is raw material for LAB is extracted from kerosene feed (UOP Molex unit)
UOP Molex unit Feed kerosene N paraffin (C10- C13) (Normal amp (Raw material for LAB) Non-normal paraffin)
8 of 72
In Back End this Normal paraffin is dehydrogenated to linear olefins (UOP Pacol unit)The linear olefins are then alkylated with benzene to LAB
UOP Pacol unit(Dehydrogenation)N paraffin (C10- C13) Linear Olefins (C10-C13)
HF acid catalystC10C13 olefins + Benzene Linear alkyl benzene (LAB)
Detail Description of Process
1) Front EndAs described earlier Normal paraffin (C10 to C13) is extracted from kerosene feed by UOP molex process The kerosene feed stock contains various carbon-chained compounds ranging from C7 to C17 This kerosene is processed in front end in series of processes they are
a) Prefractionation b) Hydrobon c) Molex
a) PREFRACTIONATION
The kerosene is fed to Prefractionation unit where heart cut kerosene of carbon chain C 10 to C14
is separated in two distillation columns in series
1) Stripper column
In this distillation column lighter compounds less than C10 are separated from top as
distillate The bottoms from the column is fed to second distillation column called
Rerun column
2) Rerun columnIn this column Heart cut kerosene of C10 to C14 is separated from top as distillate
9 of 72
STRIPPER
RERUN
Heart cut Kerosene (C10 to C14)
Light Kerosene
Feed kerosene
Heavy kerosene
b) HYDROBON
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit The catalyst used in Hydrobon reactor is S12 (Nickel ndashmolybdenumumoxide on alumina)
The heartcut kerosene from Prefractionation rerun column overhead is fed to this Hydrobon unit to remove sulfur nitrogen below 1 ppm This reaction is called as hydrotreating In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor
10 of 72
C-C-C-C-SH + H2 C-C-C-C + H2SOrganic sulfur(Mercaptan)
+ H2 C-C-C-C-C + NH3 N Nitrogen compound (Pyridine)
The reaction temperature is maintained at 310DegC while pressure is maintained at 65kgcm2g
The reactor temperature is maintained by charge heater where heat input is given by firing fuel
oil A recycle gas compressor and makeup gas compressor maintains the reactor pressure to 65
kgcm2g The H2 required for reaction is compressed in makeup gas compressor upto reactor
pressure
At reaction temperature cracking also takes place where some lighter (ltC10) are formed To
separate this the reactor effluent is passed to distillation column called Product Stripper The off
gases separated in stripper are burnt in heater as fuel
The H2S and NH3 formed in reaction form the ammonium sulfide salts The water is injected in
reactor effluent to prevent the deposition of salts that can corrode and foul the coolers The
desolved salts in water are further treated in sour water stripper to separate H2S and NH3 which
are burnt in heater as off gas
11 of 72
ProductSeparator
PRODUCT
STR
Lighters andOff gases
H2 from makeup gas compressor
Hydrobon reactor
To Molex unit
Charge heater
Feed from Prefractionation
Block Diagram of Hydrobon unit
c) MOLEX Molex process is effective method of separating normal paraffin from stream of hydrocarbon having normal and non-normal by physical selective adsorption process
The process uses solid adsorbent (Molecular sieve) where normal paraffin of straight chains are adsorbed in selective pores and non normal of branched chain are adsorbed in non selective pores
The adsorbed normal paraffin are then desorbed by normal pentane while non normal are desorbed by iso-octane
12 of 72
CHAMBER
CHAMBER
ROTARY VALVE
EXTRACT
RAFFINATE
Normal paraffin Non Normal
There are two adsorption chambers with 24 beds The process simulates countercurrent contact between fixed bed adsorbent and feed stream This simulation is done by flow directing device called ldquoRotary valverdquo
The separated streams from Molex chambers containing normal paraffin (Extract) and non normal (Raffinate) are fed to two distillation columns a) Extract column and b) Raffinate column In both distillation columns desorbent is separated from top and sidecut and recycled for desorption While bottom product of Extract column is Normal paraffin send to storage
E R
F
D
13 of 72
STRIPPER
RERUN
Heart cut Paraffin (C10 to C13)
Light NP
Feed NP
Heavy NP
2) Back EndAs described earlier Linear alkyl benzene (LAB) is produced from linear olefins by UOP detergent alkylation process The raw material normal paraffin of C10 to C14 from front end is processed in back end in series of processes they are
a) Prefractionation b) Pacol c) Alkylation
a) PREFRACTIONATION The normal paraffin of C10 to C14 carbon range is separated to Normal paraffin of C10 to C13 carbon range in two distillation columns in series
1) Stripper column In this distillation column lighter compound (if any) and partly C10 paraffin is removed as light normal paraffin (LNP) from top This LNP is sold in market as byproduct The bottoms is send to Rerun column
2) Rerun ColumnIn this column heartcut paraffin (C10 to C13) is separated from top as distillate The bottoms containing mainly C14 paraffin is sold in market as heavy normal paraffin (HNP) as byproduct
14 of 72
b) PACOL (Paraffin converted to olefin)
The normal paraffin of carbon range C10 to C13 is converted to linear olefins of carbon range C10 to C13 by Dehydrogenation reaction in UOP Pacol process
The catalyst used in reactor is alumina based platinum catalyst
Platinum catalyst
CH3-C-C-C-CH3 CH3 - C = C ndash C ndash CH3 + H2
N paraffin Linear Mono olefins
There are some side reactions takes places in Pacol they are
CH3 - C = C ndash C ndash CH3 CH3 - C = C = C ndash CH3 + H2
Linear Mono olefins Linear Di olefins
CH3 - C = C = C ndash CH3 Aromatics + H2
Linear Di olefins
As it is dehydrogenation reaction H2 gas is separated from reactor effluent in contact condenser and send to Front End for Hydrobon makeup gas compressor
Cracking also takes place in reactor where ltC10 paraffin and olefins are formed which is removed in distillation column called Pacol stripper The gas separated in stripper is burnt in heater as off gases
The reaction temperature is 470 to 495 DegC while pressure is kept low at 13 kgcm2g
The life of pacol catalyst is about 30 to 40 days As life of the catalyst is low there are two pacol reactors for continuous running of the plant
The conversion of paraffin is about 12 to 13
15 of 72
ContactCondenser
PACOL
STPR
Lighters andOff gases
Pacol reactor
To Alkylation
Charge heater
Normal ParaffinFeed
H2 to front end
DEFINE UNIT
The main purpose of this unit is to increase overall yield of LAB The Diolefins formed in Pacol reaction is converted to Mono olefins and normal paraffin thereby generating more LAB and lesser byproducts
The catalyst used in this reactor is Nickel based on alumina
Nickel catalyst
Diolefins + H2 Mono olefins
Diolefins + H2 Normal Paraffin
The reaction temperature is 180 DegC and pressure is 140 Kgcm2g
Block Diagram of Pacol Unit
16 of 72
IMIXER
2MIXER
HFSTRIPPER
C) ALKYLATION
As described earlier linear olefins (C10 to C13) are alkylated in this unit to form Linear alkyl Benzene (LAB) in presence of HF acid catalyst
The mono olefins are conveterd to Linear alkyl benzene (LAB) while diolefins are conveterd to Heavy alkyl Benzene (HAB) The aromatics are extracted in counter current extraction of HF acid and are separated in distillation column called Acid regenerators
HF acid catalyst
R- CH = CH ndashCH2 ndash Rrsquo + Benzene R-CH-CH2-CH2-Rrsquo
M Olefins
Where R and Rrsquo are alkyl groups (CH3) LAB
R-CH=CH-CH=CH-Rrsquo + 2 Benzene Heavy alkyl benzene
Di olefins HAB
The reaction is instantaneous and carried through a two stage mixer settler system The reactor section effluent is then processed in series of distillation columns where excess Benzene Paraffin LAB and byproduct Heavy alkyl benzene (HAB) gets separated
The separated benzene is recycled back to HF alkylation reactor while separated Paraffin is recycled to Pacol reactor for reaction The product Linear alkyl benzene (LAB) and byproduct Heavy alkyl benzene (HAB) are send to storage
The aromatics and non-normal which are formed in Pacol reaction are extracted in HF reaction unit by counter current extraction of HF acid as POLYMER This polymer is separated in Acid regenerators and then neutralized with KOH and send to storage
Block Diagram of Alkylation process
17 of 72
PROCESS INPUTS amp OUTPUTS
18 of 72
As described earlier plant is divided into two sections
a) Front End for Normal paraffin production from Keroseneb) Back End for Linear alkyl Benzene (LAB) production from N paraffin
The raw material kerosene is supplied to the plant from two sources
a) From Bharat Petroleum Corp Ltd Chembur (BPCL) via 55 Km pipelineb) From Reliance Petroleum Ltd Jamnagar via Shipping
The light kerosene heavy kerosene and Raffinate from front end are combined and send as return kerosene via pipeline or shipping to either BPCL or to RPL Jamnagar
The manufacturing of LAB is done in two grades
a) Domestic grade (Molecular weight 235 to 239)b) Export grade (Molecular weight 239 to 240)
The byproducts of LAB plant are
a) Light Normal paraffinb) Heavy normal paraffinc) Heavy alkyl Benzened) Tar polymer
Installed Capacities
A) For Normal Paraffin 115000 MT Highest prod 126596 MT in year 2001-2002
B) For LAB 100000 MT Highest prod 112484 MT in year 1999-2000
Plant load
A) For Normal Paraffin 117
B) For LAB 120 Production per day
A) For Normal Paraffin 330 MT day (Avrg)
B) For LAB 324 MTday (Avrg)
Customers
19 of 72
1) The Normal paraffin produced in LAB plant is normally used for captive consumption for producing LAB
2) The main customer of LAB is Ms Hindustan Lever and Procter amp Gamble Ltd and their subsidiary
3) The LAB is exported to Europe American African and Asian countries4) The light and Heavy normal paraffin is used to manufacture Chlorinated Paraffin Wax5) Heavy alkyl Benzene is used as lubricants in oil industry
Utility system in LAB plant
Hot oil system
There are two Hot oil Heaters available in LAB plant one for Front End and other is for Back End The Heaters are fired with furnace oil LSHS and off gases from process
The Hot oil (Dow Therm) which is thermic fluid is heated in these Hot oil heaters
The all heat inputs to the column preheater are given by circulating Hot oil at supply temperature of 330 DegC
Effluent System
The effluent generated in LAB plant mainly constitute
a) Fluoride Maximum limit lt 10 ppmb) Oil Maximum limit lt 10 ppm
For reduction of fluoride in effluent water LAB plant have two neutralisation basins where effluent from HF area is collected and then reacted with Lime (CaCO3) to reduce fluoride content below 10ppm
For reduction of oil in effluent water LAB plant have CPI separator installed to separate oil from effluent water The oil separated is send to Slope oil storage
In addition to this there is hydrocarbon pit installed in front end to collect pump and filter drains which is being blended in return kerosene to reduce oil load in effluent systemThere all oil collection pits installed in storm water channels to avoid oil going into the river via gates
20 of 72
Cooling water systemFor cooling the final products Byproducts to normal ambient temperatures the products byproducts are cooled in coolers The cooling media used is water There are three cooling towers installed in LAB planta) HF cooling tower it is separate cooling tower to avoid HF ingrace in coolers in non-HF
areab) Front End Cooling towerc) Back End cooling tower
Fin Fan coolers The distillation columns overheads are condensed in air-cooled fin fan coolers The advantage of these coolers over water-cooled coolers is low operating cost
Safety measures taken in LAB Plant
1) Safety Interlocks for tripping the operation of equipments in case process variables touches maximum allowable value
2) Flare system for burning excess gases from process3) Infra red detection system for Pacol Reactor and Hot pumps 4) Hydrocarbon detection system for detecting hydrocarbon leakages5) H2S detection system and siren for detecting H2S gas leakages 6) HF Detection system for detecting HF leakages7) Schedule HF leak testing of HF flanges8) Application of HF detection paints to all HF flanges to detect HF leak by decolouration9) Schedule Thickness survey of pipelines in HF area 10) Fire water sprinkler system for HF vessels Columns and pumps11) Fire water sprinkler system for Hot oil pumps12) Yellow boundary marking of HF area where personal protective equipments (PPErsquos) are
mandatory 13) Personal protective equipments (PPErsquos) for HF area Different types of PVC suits are defined
for different types of jobs ( A B C and D type)14) Separate breathing air reciprocating compressor for breathing air for C and D type PVC
suits in case of eemergency15) KOH scrubbing for venting from all HF equipments so that HF will not release into the
flare16) Daily Benzene monitoring with dragger tubes to detect any Benzene leaks from process17) Close draining system of HF and Benzene
21 of 72
PROJECT ndashI
The project is about developing a ldquoBENZENE-WATER WASHrdquo system to remove the impurities coming with fresh benzene that enters into benzene stripper and effects thefin-fan cooler The project is about developing such a scheme which will remove these impurities before entering the benzene stripper to eliminate the failure of fin-fan cooler
The scheme should also be such that it should not reduce the efficiency of the equipment and should be cost-effective
What is Benzene stripper
The high volatility of water dissolved in hydrocarbons is used in this column to obtain water-free benzene in the column bottoms which also removes any dissolved oxygen or non-condensibles in the benzene or off spec feeds Makeup benzene is fed to the overhead receiver on level control reset by the overhead receiver level controller It is refluxed via the overhead pump on flow control reset by the column bottom level controller and sent to the reaction section by the bottoms pump via the benzene stripper feedbottoms exchanger on flow control which is reset by the benzene column receiver level controller The benzene stripper receiver floats on the flare and is sized big enough to allow enough settling time for the water There is a small nitrogen flow via a conservation vent into the receiver vapor flare to maintain a slight nitrogen purge Water is collected in the boot and drained periodically whenever there is a boot high alarm Maintain a visible benzene water interface in the boot sight glass The benzene at the column bottom normally has a water content of less than 20ppm actually much lower if the column is operated well A moisture analyzer alarm high is provided The heat input to the column is provided by a hot oil reboiler with the hot oil flow controlled Off-spec material from the off-spec tank is normally rerun via the benzene stripper coming into the column receiver
What is the Issue
The benzene stripper column overheads are condensed in air-cooler (fin-fan coolers EC-301)The advantage of using this fin-fan cooler is the low operating cost no space constraint as are not on ground level etc This tube-bundle was failing at a frequency of once in a span of two years Failure analysis study was carried out and found that there are some impurities coming along with fresh benzene which are forming acidic solution after condensing in fin-fan This acidic solution formed was causing the repeated failure of tube-bundle
Water dosing was started upstream of the fin-fan bundle to dissolve out the impurities or to neutralize the acidic solution so that tubes can be saved This practice was started in 2008 Even after this modification the failures and continue and its difficult to analyze that what type of impurities are coming with benzene
22 of 72
So to eliminate this problem a scheme has been plotted to design a benzene scrubbing system This will be basically washing of benzene with DM water to remove the impurities before it enters the benzene stripper
The schematic diagram of this system is shown below
The scheme consists of a static mixture for mixing benzene and water for a particular residence time and at a particular velocity as required A gravity settler is for separating benzene and water on the basis of density difference
23 of 72
STATIC MIXER
This mixing device has no moving parts is simple and its cost can be quite reasonable when compared to mechanical driven mixers Static or motionless mixers are relatively new development and have proven to be effective for many specific and valuable process application It is useful for a wide range of viscosity fluids particularly useful in liquid-liquid mixing and also for some gas-liquid dispersion
The concept of motionless mixers is to achieve a uniform composition and temperature distribution in fluids flowing through the device The concept is build around a stationary rigid element placed in a pipe or cylinder that uses the energy of fluid flowing past to produce the mixing The unit becomes more efficient by adding additional static elements causing the flowing fluid elements to split rearrange recombine and split again to repeat the process lsquoxrsquo times for a uniform or homogeneous flowing stream is produced at discharge
Principle of operation
The static mixer unit is a series of fixed helical elements enclosed within a tubular housing
LIQUID ndash LIQUID SEPARATION(Decanters)
Separation of two liquid phases immiscible or partially miscible liquids is a common requirement in the process industries It is also frequently necessary to separate small quantities of entrained water from process streams The simplest form of equipment used to separate liquid phases is the gravity settling tank the decanter Various proprietary equipment is also used to promote coalescence and improve separation in difficult systems or where emulsions are likely to form Centrifugal separators are also used
Decanters (settlers)
Decanters are used to separate liquids where there is a sufficient difference in density between the liquids for the droplets to settle readily Decanters are essentially tanks which give sufficient residence time for the droplets of the dispersed phase to rise (or settle ) to the interface between the phases and coalesce
In an operating decanter there will be three distinct zones or bands clear heavy liquid separating dispersed liquid (the dispersion zone) and clear light liquid The position of the interface can be controlled with or without the use of instruments by use of a siphon take-off for the heavy liquid
24 of 72
Vertical decanter
The height of the take-off can be determined by making a pressure balance Neglecting friction loss in the pipes the pressure exerted by the combined height of the heavy and light liquid in the vessel must be balanced by the height of the heavy liquid in the take-off leg
(z1-z3)Ρ1g + z3 Ρ2g= z2 Ρ2g
z2 = (z1-z3) Ρ1 + z3 (1)Ρ2
WhereZ1= height from datum to light liquid overflow m Z2=height from datum to heavy liquid overflow m Z3=height from datum to interface m Ρ1=density of the light liquid kgmsup3 Ρ2=density of the heavy liquid kg msup3
The height of the liquid interface should be measured accurately when the liquid densities are close when one component is present only in small quantities or when the throughput is very small A typical scheme for the automatic control of the interface using a level instrument that can detect the position of the interface is shown in the diagram below Where one phase is present only in small amounts it is often recycled to the decanter feed to give more stable operation
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CALCULATIONS
STATIC MIXER DESIGN
Required data
1 Physical properties of materials Density kgmsup3
Viscosity Pas = 0001Cp
2 Pressure drop Pressure drop in static mixer is best described by comparison with pipe flow
3 Geometrical parameters Diameter m
Type of static mixer constant (k)
Length (l) m
4 Process variables
Flow rate msup3s TemperaturedegC Pressure bar
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Pressure drop calculation
a) Velocity (v)
V = Qπ4 Dsup2
b) Reynoldsrsquos number(Re)
Re= dvρμ
c) Pressure drop (Δp)For Re lt50 Δp =k1x μ x l xQd dsup3
k1= laminar flow constant
For Re gt10sup3 Δp =k2 x ρ x l x vsup2d 2
= k2 x Q x l x 8 x Qsup2d prodsup2 d⁴
k2= turbulent flow constant
Pipe diameter Flow seems to be turbulent as both the materials (B2+ H2O) are not viscous
D =39Q ⁰ ⁴⁵ ρ sup1sup3⁰
Q =52 + 572 = 1092msup3hr = 303 x 10macrsup3msup3s= 38564 ftsup3hr
Ρ = 926328 kgmsup3 =57828 lbftsup3
D =39 x Q ⁰ ⁴⁵ x ρ sup1sup3⁰
D =39 x (38564) ⁰ ⁴⁵ x (57828) sup1sup3⁰ 3600
D= 24 inch = 25 inch = 00635m
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Velocity(v)
V =4 Q proddsup2
= 303 x 10macrsup3 msup3s x 4 314 x (00635)sup2
= 0957 ms (approx 1ms)
Reynoldrsquosnumber(Re)
Re = dvρ Μ = 00635 x 1 x 926328 0572
Re =103 x 10⁵
Thus the flow is highly turbulent
Flow regime Reynoldrsquos no(Re)
No of element No of elements to add if viscosity ratio between fluids exceeds 10001
No of elements to add if volumetric ratio between fluids exceeds 1001
Laminar lt1 24 6 61-10 18 6 611-50 14 6 651-100 12 6 6101-500 10 6 6
Transitional 501-1000 8 4 41001-2000 6 4 4
Turbulent 2001-5000 4 2 25001+ 2 2 2
Thus from the above table the mixer will have 2 elements
The mixer length will be based on the number of elements required An approximate length can be determined by multiplying the number of elements by 15
Mixer length = 15 x 2 =3
28 of 72
For turbulent flow applications it is generally recommended that a minimum velocity of 10 ftsec be maintained
V= 0408 x QDsup2 = 0408 x 4813sup2 = 218 ftsec =066 ms
DECANTER DESIGN
Benzene Water
Flow rate (msup3h) 52 572
Flow rate (kgh) 4543812 570311
Density (kgmsup3) 87381 99704
Viscosity (Pas) 0000604 000089
Take Dd = 150microm
microd = (150 Х 10ˉ⁶)sup2 Х 981 Х (87381-99704) 18 Х 000089
microd = -169787 Х 10ˉsup3 ms = -17 mms (rising)
As the flow rate is small we will use a vertical cylindrical vessel
The decanter vessel is sized on the basis that the velocity of the continuous phase must be less than settling velocity of the droplets of the dispersed phase Plug flow is assumed and the velocity of the continuous phase calculated using the area of the interfacemicroc =Lclt microdAiWhere microd = settling velocity of the dispersed phase droplets msmicroc = velocity of the continuous phase msLc = continuous phase volumetric flow rate msup3sAi = area of the interface msup2
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Lc = 570311 X 1 99704 3600
= 00015889 msup3s
Ai=Lc = 00015889 microc 00017
= 0935817588 msup2
For a vertical cylindrical decanterAi = prodrsup2
r = 0935817588 prodr = 0545835318 m
Diameter= 1091670637 m
Taking the height as twice the diameter a reasonable value for a cylinder
Height = 2183341274 m
The position of the interface should be such that the band of droplets that collect at the interface waiting to coalesce and cross the interface does not extend to the bottom (or top) of the vessel The depth of the dispersion band is a function of the liquid flow rate and the interfacial area A value of to per cent of the decanter height is usually taken for the design purposes
Take the dispersion band as 10 per cent of the height = 021833mThe residence time of the droplets in the dispersion band = 021833 = 021833microd 00017 =1285926 s (approx 2 min)
This is satisfactory time a time of 2 to 5 min is normally recommended Thus the size of the water (continuous heavy phase) droplets that could be entrained with benzene (light phase) will be
Velocity of benzene phase = 4543812 X 1 X 1 873811 3600093581
=0001543511 ms =1543511mms
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So from equation ( ) So the entrained droplet size will be =00015435 X 18 X 0000604 frac12 981 X (99704-873812)
=00001178 m=1178 microm
which is satisfactory below 150 microm
Piping arrangement
To minimize entrainment by the jet of liquid entering the vessel the inlet velocity for a decanter should keep below 1 ms
The velocity from static mixer= 066 ms
Flow rate= 4543812 + 570311 X 1 87381 99704 3600
= 0003033345msup3s
Area of pipe= flow ratevelocity
= 0003033345066
= 0004554572msup2
Pipe diameter =0004554572 x 4prod
= 0076158749 m =29983 inch (approx 3 in)
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PROJECT II
CALULATING THE DEW POINT
This project is about the study and evaluation of the performance of the compressors in the Hydrobon section of the LAB plant which is installed to optimize the purity of hydrogen coming from the product separators The compressors in this section include recycle gas compressor and make-up gas compressorThe purity of hydrogen can be increased upto 90
This project will give the company an overall view of this loop The plant is running well about its installed capacity(131-140) The company wants to retain the purity level of nearly 90 for hydrogen even after operating above installed capacity Hence the current project will give the company an idea of the current hydrogen quality(purity) which is obtained and give an idea about changes if any to be made to existing process set-up
HYDROBON REACTOR
Hydrobon reactor is designed to remove contaminants present in the raw kerosene without changing the boiling range The hydrocarbon is passed through a 2 bed reactor feed with S 12 catalyst through a feed effluent exchanger and charge heater which maintain the required reaction temperature(310 c) The reaction required hydrogen gas which is supplied from pacol net gas generated from back end and tattoray hydrogen from PX plantThe reaction charge is heated to the reaction temperature in the charge heater enters the reactor from the top and is distributed over the catalyst bed Catalytic hydrogenation takes place in the reactor The impurities react with hydrogen and form salts which are subsequently separated and finally removed in sour water stripper The reactor effluents after separation is fed to the product stripper to remove lighters and hydrotreated kerosene is fed to molex unit The sulfur and nitrogen levels are reduced to 1 ppm or less
PARAMETERS DESIGN ACTUALPlant load() 100 115Hydrobon feed rate(mthr) 58 60Temperature 416 310Pressure (kgcm2 g) 822 62H2HC ratio 385 460Recycle hydrogen purity(mole)
75 min 95
Hydrobon feed specificationa Bromine
index(mg100gm)800 800
38 of 72
b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
39 of 72
HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
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4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
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FLOW DIAGRAM OF HYDROBON SECTION
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Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
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nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
44 of 72
Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
45 of 72
DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
47 of 72
ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
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Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
49 of 72
Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
50 of 72
Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
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=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
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Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
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Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
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Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
55 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
COMPANY INFORMATION
Reliance Industries Limited found by Dhirubhai H Ambani is Indiarsquos largest private sector enterprise with businesses in the energy and materials value chain Grouprsquos annual revenues are in excess of US$ 28 billion The flagship company of RIL is a Fortune Global 500 company and its largest private sector company in India
Backward vertical integration has been the cornerstone of the evolution and growth of Reliance Starting with textiles in the late seventies Reliance pursued a strategy of backward vertical integration in polyesters fibre intermediates plastics petrochemicals petroleum refining and oil and gas exploration and production ndash to be fully integrated along the materials and energy value chain
Reliance enjoys global leadership in its businesses being the largest polyester yarn and fibre producer in the world and among the top ten producers in the world in major petrochemical products
Major Group Companies are Reliance Industries Limited (including main subsidiary Reliance Retail Limted ) and Reliance Industrial Infrastructure Limited
6 of 72
LAB (Linear Alkyl Benzene) Process Overview
Introduction
The linear alkylbenzenes produced from C10-C13 linear olefins are useful detergent intermediates and can be readily sulfonated to yield linear alkylbenzensulfonates
HF acid catalystC10C13 olefins + Benzene Linear alkyl benzene (LAB)
SulfonationLinear Alkyl benzene (LAB) LAB sulfonates
These compounds constitute the ldquoactiverdquo ingredients of many household detergents They are surface-active compounds (surfactants) which are combined with various builders (often inorganic salts) to make up a detergent formula
BuildersLAB sulfonates House hold Detergents
Typical Detergent formulation
LAB sulfonates 25wt
Sodium tripolyphosphate 40 wt
Sodium silicate 10 wt
Sodium sulfate 16 wt
Water 8 wt
Carboxymethylcellulose 1 wt
7 of 72
History
During 1940rsquos and 1950rsquos the detergent market was primarily captured by dodecylbenzene (DDB) a product formed by alkylation of Benzene with propylene tetramer It was found that detergent formed by this was giving poor biodegradability of detergent
Propylene tetramer + Benzene Dodecylbenzene (DDB) (Low biodegradability)
Thus LAB introduced in early 60rsquos have substantially replaced this DDB which is having good biodegradability (gt95)
Process Description
Brief Overview
LAB manufacturing process is a technology patented by UOP Inc (Universal oil Product)
The LAB plant is divided into two parts called
a) Front Endb) Back End
In Front End Normal paraffin which is raw material for LAB is extracted from kerosene feed (UOP Molex unit)
UOP Molex unit Feed kerosene N paraffin (C10- C13) (Normal amp (Raw material for LAB) Non-normal paraffin)
8 of 72
In Back End this Normal paraffin is dehydrogenated to linear olefins (UOP Pacol unit)The linear olefins are then alkylated with benzene to LAB
UOP Pacol unit(Dehydrogenation)N paraffin (C10- C13) Linear Olefins (C10-C13)
HF acid catalystC10C13 olefins + Benzene Linear alkyl benzene (LAB)
Detail Description of Process
1) Front EndAs described earlier Normal paraffin (C10 to C13) is extracted from kerosene feed by UOP molex process The kerosene feed stock contains various carbon-chained compounds ranging from C7 to C17 This kerosene is processed in front end in series of processes they are
a) Prefractionation b) Hydrobon c) Molex
a) PREFRACTIONATION
The kerosene is fed to Prefractionation unit where heart cut kerosene of carbon chain C 10 to C14
is separated in two distillation columns in series
1) Stripper column
In this distillation column lighter compounds less than C10 are separated from top as
distillate The bottoms from the column is fed to second distillation column called
Rerun column
2) Rerun columnIn this column Heart cut kerosene of C10 to C14 is separated from top as distillate
9 of 72
STRIPPER
RERUN
Heart cut Kerosene (C10 to C14)
Light Kerosene
Feed kerosene
Heavy kerosene
b) HYDROBON
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit The catalyst used in Hydrobon reactor is S12 (Nickel ndashmolybdenumumoxide on alumina)
The heartcut kerosene from Prefractionation rerun column overhead is fed to this Hydrobon unit to remove sulfur nitrogen below 1 ppm This reaction is called as hydrotreating In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor
10 of 72
C-C-C-C-SH + H2 C-C-C-C + H2SOrganic sulfur(Mercaptan)
+ H2 C-C-C-C-C + NH3 N Nitrogen compound (Pyridine)
The reaction temperature is maintained at 310DegC while pressure is maintained at 65kgcm2g
The reactor temperature is maintained by charge heater where heat input is given by firing fuel
oil A recycle gas compressor and makeup gas compressor maintains the reactor pressure to 65
kgcm2g The H2 required for reaction is compressed in makeup gas compressor upto reactor
pressure
At reaction temperature cracking also takes place where some lighter (ltC10) are formed To
separate this the reactor effluent is passed to distillation column called Product Stripper The off
gases separated in stripper are burnt in heater as fuel
The H2S and NH3 formed in reaction form the ammonium sulfide salts The water is injected in
reactor effluent to prevent the deposition of salts that can corrode and foul the coolers The
desolved salts in water are further treated in sour water stripper to separate H2S and NH3 which
are burnt in heater as off gas
11 of 72
ProductSeparator
PRODUCT
STR
Lighters andOff gases
H2 from makeup gas compressor
Hydrobon reactor
To Molex unit
Charge heater
Feed from Prefractionation
Block Diagram of Hydrobon unit
c) MOLEX Molex process is effective method of separating normal paraffin from stream of hydrocarbon having normal and non-normal by physical selective adsorption process
The process uses solid adsorbent (Molecular sieve) where normal paraffin of straight chains are adsorbed in selective pores and non normal of branched chain are adsorbed in non selective pores
The adsorbed normal paraffin are then desorbed by normal pentane while non normal are desorbed by iso-octane
12 of 72
CHAMBER
CHAMBER
ROTARY VALVE
EXTRACT
RAFFINATE
Normal paraffin Non Normal
There are two adsorption chambers with 24 beds The process simulates countercurrent contact between fixed bed adsorbent and feed stream This simulation is done by flow directing device called ldquoRotary valverdquo
The separated streams from Molex chambers containing normal paraffin (Extract) and non normal (Raffinate) are fed to two distillation columns a) Extract column and b) Raffinate column In both distillation columns desorbent is separated from top and sidecut and recycled for desorption While bottom product of Extract column is Normal paraffin send to storage
E R
F
D
13 of 72
STRIPPER
RERUN
Heart cut Paraffin (C10 to C13)
Light NP
Feed NP
Heavy NP
2) Back EndAs described earlier Linear alkyl benzene (LAB) is produced from linear olefins by UOP detergent alkylation process The raw material normal paraffin of C10 to C14 from front end is processed in back end in series of processes they are
a) Prefractionation b) Pacol c) Alkylation
a) PREFRACTIONATION The normal paraffin of C10 to C14 carbon range is separated to Normal paraffin of C10 to C13 carbon range in two distillation columns in series
1) Stripper column In this distillation column lighter compound (if any) and partly C10 paraffin is removed as light normal paraffin (LNP) from top This LNP is sold in market as byproduct The bottoms is send to Rerun column
2) Rerun ColumnIn this column heartcut paraffin (C10 to C13) is separated from top as distillate The bottoms containing mainly C14 paraffin is sold in market as heavy normal paraffin (HNP) as byproduct
14 of 72
b) PACOL (Paraffin converted to olefin)
The normal paraffin of carbon range C10 to C13 is converted to linear olefins of carbon range C10 to C13 by Dehydrogenation reaction in UOP Pacol process
The catalyst used in reactor is alumina based platinum catalyst
Platinum catalyst
CH3-C-C-C-CH3 CH3 - C = C ndash C ndash CH3 + H2
N paraffin Linear Mono olefins
There are some side reactions takes places in Pacol they are
CH3 - C = C ndash C ndash CH3 CH3 - C = C = C ndash CH3 + H2
Linear Mono olefins Linear Di olefins
CH3 - C = C = C ndash CH3 Aromatics + H2
Linear Di olefins
As it is dehydrogenation reaction H2 gas is separated from reactor effluent in contact condenser and send to Front End for Hydrobon makeup gas compressor
Cracking also takes place in reactor where ltC10 paraffin and olefins are formed which is removed in distillation column called Pacol stripper The gas separated in stripper is burnt in heater as off gases
The reaction temperature is 470 to 495 DegC while pressure is kept low at 13 kgcm2g
The life of pacol catalyst is about 30 to 40 days As life of the catalyst is low there are two pacol reactors for continuous running of the plant
The conversion of paraffin is about 12 to 13
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ContactCondenser
PACOL
STPR
Lighters andOff gases
Pacol reactor
To Alkylation
Charge heater
Normal ParaffinFeed
H2 to front end
DEFINE UNIT
The main purpose of this unit is to increase overall yield of LAB The Diolefins formed in Pacol reaction is converted to Mono olefins and normal paraffin thereby generating more LAB and lesser byproducts
The catalyst used in this reactor is Nickel based on alumina
Nickel catalyst
Diolefins + H2 Mono olefins
Diolefins + H2 Normal Paraffin
The reaction temperature is 180 DegC and pressure is 140 Kgcm2g
Block Diagram of Pacol Unit
16 of 72
IMIXER
2MIXER
HFSTRIPPER
C) ALKYLATION
As described earlier linear olefins (C10 to C13) are alkylated in this unit to form Linear alkyl Benzene (LAB) in presence of HF acid catalyst
The mono olefins are conveterd to Linear alkyl benzene (LAB) while diolefins are conveterd to Heavy alkyl Benzene (HAB) The aromatics are extracted in counter current extraction of HF acid and are separated in distillation column called Acid regenerators
HF acid catalyst
R- CH = CH ndashCH2 ndash Rrsquo + Benzene R-CH-CH2-CH2-Rrsquo
M Olefins
Where R and Rrsquo are alkyl groups (CH3) LAB
R-CH=CH-CH=CH-Rrsquo + 2 Benzene Heavy alkyl benzene
Di olefins HAB
The reaction is instantaneous and carried through a two stage mixer settler system The reactor section effluent is then processed in series of distillation columns where excess Benzene Paraffin LAB and byproduct Heavy alkyl benzene (HAB) gets separated
The separated benzene is recycled back to HF alkylation reactor while separated Paraffin is recycled to Pacol reactor for reaction The product Linear alkyl benzene (LAB) and byproduct Heavy alkyl benzene (HAB) are send to storage
The aromatics and non-normal which are formed in Pacol reaction are extracted in HF reaction unit by counter current extraction of HF acid as POLYMER This polymer is separated in Acid regenerators and then neutralized with KOH and send to storage
Block Diagram of Alkylation process
17 of 72
PROCESS INPUTS amp OUTPUTS
18 of 72
As described earlier plant is divided into two sections
a) Front End for Normal paraffin production from Keroseneb) Back End for Linear alkyl Benzene (LAB) production from N paraffin
The raw material kerosene is supplied to the plant from two sources
a) From Bharat Petroleum Corp Ltd Chembur (BPCL) via 55 Km pipelineb) From Reliance Petroleum Ltd Jamnagar via Shipping
The light kerosene heavy kerosene and Raffinate from front end are combined and send as return kerosene via pipeline or shipping to either BPCL or to RPL Jamnagar
The manufacturing of LAB is done in two grades
a) Domestic grade (Molecular weight 235 to 239)b) Export grade (Molecular weight 239 to 240)
The byproducts of LAB plant are
a) Light Normal paraffinb) Heavy normal paraffinc) Heavy alkyl Benzened) Tar polymer
Installed Capacities
A) For Normal Paraffin 115000 MT Highest prod 126596 MT in year 2001-2002
B) For LAB 100000 MT Highest prod 112484 MT in year 1999-2000
Plant load
A) For Normal Paraffin 117
B) For LAB 120 Production per day
A) For Normal Paraffin 330 MT day (Avrg)
B) For LAB 324 MTday (Avrg)
Customers
19 of 72
1) The Normal paraffin produced in LAB plant is normally used for captive consumption for producing LAB
2) The main customer of LAB is Ms Hindustan Lever and Procter amp Gamble Ltd and their subsidiary
3) The LAB is exported to Europe American African and Asian countries4) The light and Heavy normal paraffin is used to manufacture Chlorinated Paraffin Wax5) Heavy alkyl Benzene is used as lubricants in oil industry
Utility system in LAB plant
Hot oil system
There are two Hot oil Heaters available in LAB plant one for Front End and other is for Back End The Heaters are fired with furnace oil LSHS and off gases from process
The Hot oil (Dow Therm) which is thermic fluid is heated in these Hot oil heaters
The all heat inputs to the column preheater are given by circulating Hot oil at supply temperature of 330 DegC
Effluent System
The effluent generated in LAB plant mainly constitute
a) Fluoride Maximum limit lt 10 ppmb) Oil Maximum limit lt 10 ppm
For reduction of fluoride in effluent water LAB plant have two neutralisation basins where effluent from HF area is collected and then reacted with Lime (CaCO3) to reduce fluoride content below 10ppm
For reduction of oil in effluent water LAB plant have CPI separator installed to separate oil from effluent water The oil separated is send to Slope oil storage
In addition to this there is hydrocarbon pit installed in front end to collect pump and filter drains which is being blended in return kerosene to reduce oil load in effluent systemThere all oil collection pits installed in storm water channels to avoid oil going into the river via gates
20 of 72
Cooling water systemFor cooling the final products Byproducts to normal ambient temperatures the products byproducts are cooled in coolers The cooling media used is water There are three cooling towers installed in LAB planta) HF cooling tower it is separate cooling tower to avoid HF ingrace in coolers in non-HF
areab) Front End Cooling towerc) Back End cooling tower
Fin Fan coolers The distillation columns overheads are condensed in air-cooled fin fan coolers The advantage of these coolers over water-cooled coolers is low operating cost
Safety measures taken in LAB Plant
1) Safety Interlocks for tripping the operation of equipments in case process variables touches maximum allowable value
2) Flare system for burning excess gases from process3) Infra red detection system for Pacol Reactor and Hot pumps 4) Hydrocarbon detection system for detecting hydrocarbon leakages5) H2S detection system and siren for detecting H2S gas leakages 6) HF Detection system for detecting HF leakages7) Schedule HF leak testing of HF flanges8) Application of HF detection paints to all HF flanges to detect HF leak by decolouration9) Schedule Thickness survey of pipelines in HF area 10) Fire water sprinkler system for HF vessels Columns and pumps11) Fire water sprinkler system for Hot oil pumps12) Yellow boundary marking of HF area where personal protective equipments (PPErsquos) are
mandatory 13) Personal protective equipments (PPErsquos) for HF area Different types of PVC suits are defined
for different types of jobs ( A B C and D type)14) Separate breathing air reciprocating compressor for breathing air for C and D type PVC
suits in case of eemergency15) KOH scrubbing for venting from all HF equipments so that HF will not release into the
flare16) Daily Benzene monitoring with dragger tubes to detect any Benzene leaks from process17) Close draining system of HF and Benzene
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PROJECT ndashI
The project is about developing a ldquoBENZENE-WATER WASHrdquo system to remove the impurities coming with fresh benzene that enters into benzene stripper and effects thefin-fan cooler The project is about developing such a scheme which will remove these impurities before entering the benzene stripper to eliminate the failure of fin-fan cooler
The scheme should also be such that it should not reduce the efficiency of the equipment and should be cost-effective
What is Benzene stripper
The high volatility of water dissolved in hydrocarbons is used in this column to obtain water-free benzene in the column bottoms which also removes any dissolved oxygen or non-condensibles in the benzene or off spec feeds Makeup benzene is fed to the overhead receiver on level control reset by the overhead receiver level controller It is refluxed via the overhead pump on flow control reset by the column bottom level controller and sent to the reaction section by the bottoms pump via the benzene stripper feedbottoms exchanger on flow control which is reset by the benzene column receiver level controller The benzene stripper receiver floats on the flare and is sized big enough to allow enough settling time for the water There is a small nitrogen flow via a conservation vent into the receiver vapor flare to maintain a slight nitrogen purge Water is collected in the boot and drained periodically whenever there is a boot high alarm Maintain a visible benzene water interface in the boot sight glass The benzene at the column bottom normally has a water content of less than 20ppm actually much lower if the column is operated well A moisture analyzer alarm high is provided The heat input to the column is provided by a hot oil reboiler with the hot oil flow controlled Off-spec material from the off-spec tank is normally rerun via the benzene stripper coming into the column receiver
What is the Issue
The benzene stripper column overheads are condensed in air-cooler (fin-fan coolers EC-301)The advantage of using this fin-fan cooler is the low operating cost no space constraint as are not on ground level etc This tube-bundle was failing at a frequency of once in a span of two years Failure analysis study was carried out and found that there are some impurities coming along with fresh benzene which are forming acidic solution after condensing in fin-fan This acidic solution formed was causing the repeated failure of tube-bundle
Water dosing was started upstream of the fin-fan bundle to dissolve out the impurities or to neutralize the acidic solution so that tubes can be saved This practice was started in 2008 Even after this modification the failures and continue and its difficult to analyze that what type of impurities are coming with benzene
22 of 72
So to eliminate this problem a scheme has been plotted to design a benzene scrubbing system This will be basically washing of benzene with DM water to remove the impurities before it enters the benzene stripper
The schematic diagram of this system is shown below
The scheme consists of a static mixture for mixing benzene and water for a particular residence time and at a particular velocity as required A gravity settler is for separating benzene and water on the basis of density difference
23 of 72
STATIC MIXER
This mixing device has no moving parts is simple and its cost can be quite reasonable when compared to mechanical driven mixers Static or motionless mixers are relatively new development and have proven to be effective for many specific and valuable process application It is useful for a wide range of viscosity fluids particularly useful in liquid-liquid mixing and also for some gas-liquid dispersion
The concept of motionless mixers is to achieve a uniform composition and temperature distribution in fluids flowing through the device The concept is build around a stationary rigid element placed in a pipe or cylinder that uses the energy of fluid flowing past to produce the mixing The unit becomes more efficient by adding additional static elements causing the flowing fluid elements to split rearrange recombine and split again to repeat the process lsquoxrsquo times for a uniform or homogeneous flowing stream is produced at discharge
Principle of operation
The static mixer unit is a series of fixed helical elements enclosed within a tubular housing
LIQUID ndash LIQUID SEPARATION(Decanters)
Separation of two liquid phases immiscible or partially miscible liquids is a common requirement in the process industries It is also frequently necessary to separate small quantities of entrained water from process streams The simplest form of equipment used to separate liquid phases is the gravity settling tank the decanter Various proprietary equipment is also used to promote coalescence and improve separation in difficult systems or where emulsions are likely to form Centrifugal separators are also used
Decanters (settlers)
Decanters are used to separate liquids where there is a sufficient difference in density between the liquids for the droplets to settle readily Decanters are essentially tanks which give sufficient residence time for the droplets of the dispersed phase to rise (or settle ) to the interface between the phases and coalesce
In an operating decanter there will be three distinct zones or bands clear heavy liquid separating dispersed liquid (the dispersion zone) and clear light liquid The position of the interface can be controlled with or without the use of instruments by use of a siphon take-off for the heavy liquid
24 of 72
Vertical decanter
The height of the take-off can be determined by making a pressure balance Neglecting friction loss in the pipes the pressure exerted by the combined height of the heavy and light liquid in the vessel must be balanced by the height of the heavy liquid in the take-off leg
(z1-z3)Ρ1g + z3 Ρ2g= z2 Ρ2g
z2 = (z1-z3) Ρ1 + z3 (1)Ρ2
WhereZ1= height from datum to light liquid overflow m Z2=height from datum to heavy liquid overflow m Z3=height from datum to interface m Ρ1=density of the light liquid kgmsup3 Ρ2=density of the heavy liquid kg msup3
The height of the liquid interface should be measured accurately when the liquid densities are close when one component is present only in small quantities or when the throughput is very small A typical scheme for the automatic control of the interface using a level instrument that can detect the position of the interface is shown in the diagram below Where one phase is present only in small amounts it is often recycled to the decanter feed to give more stable operation
25 of 72
CALCULATIONS
STATIC MIXER DESIGN
Required data
1 Physical properties of materials Density kgmsup3
Viscosity Pas = 0001Cp
2 Pressure drop Pressure drop in static mixer is best described by comparison with pipe flow
3 Geometrical parameters Diameter m
Type of static mixer constant (k)
Length (l) m
4 Process variables
Flow rate msup3s TemperaturedegC Pressure bar
26 of 72
Pressure drop calculation
a) Velocity (v)
V = Qπ4 Dsup2
b) Reynoldsrsquos number(Re)
Re= dvρμ
c) Pressure drop (Δp)For Re lt50 Δp =k1x μ x l xQd dsup3
k1= laminar flow constant
For Re gt10sup3 Δp =k2 x ρ x l x vsup2d 2
= k2 x Q x l x 8 x Qsup2d prodsup2 d⁴
k2= turbulent flow constant
Pipe diameter Flow seems to be turbulent as both the materials (B2+ H2O) are not viscous
D =39Q ⁰ ⁴⁵ ρ sup1sup3⁰
Q =52 + 572 = 1092msup3hr = 303 x 10macrsup3msup3s= 38564 ftsup3hr
Ρ = 926328 kgmsup3 =57828 lbftsup3
D =39 x Q ⁰ ⁴⁵ x ρ sup1sup3⁰
D =39 x (38564) ⁰ ⁴⁵ x (57828) sup1sup3⁰ 3600
D= 24 inch = 25 inch = 00635m
27 of 72
Velocity(v)
V =4 Q proddsup2
= 303 x 10macrsup3 msup3s x 4 314 x (00635)sup2
= 0957 ms (approx 1ms)
Reynoldrsquosnumber(Re)
Re = dvρ Μ = 00635 x 1 x 926328 0572
Re =103 x 10⁵
Thus the flow is highly turbulent
Flow regime Reynoldrsquos no(Re)
No of element No of elements to add if viscosity ratio between fluids exceeds 10001
No of elements to add if volumetric ratio between fluids exceeds 1001
Laminar lt1 24 6 61-10 18 6 611-50 14 6 651-100 12 6 6101-500 10 6 6
Transitional 501-1000 8 4 41001-2000 6 4 4
Turbulent 2001-5000 4 2 25001+ 2 2 2
Thus from the above table the mixer will have 2 elements
The mixer length will be based on the number of elements required An approximate length can be determined by multiplying the number of elements by 15
Mixer length = 15 x 2 =3
28 of 72
For turbulent flow applications it is generally recommended that a minimum velocity of 10 ftsec be maintained
V= 0408 x QDsup2 = 0408 x 4813sup2 = 218 ftsec =066 ms
DECANTER DESIGN
Benzene Water
Flow rate (msup3h) 52 572
Flow rate (kgh) 4543812 570311
Density (kgmsup3) 87381 99704
Viscosity (Pas) 0000604 000089
Take Dd = 150microm
microd = (150 Х 10ˉ⁶)sup2 Х 981 Х (87381-99704) 18 Х 000089
microd = -169787 Х 10ˉsup3 ms = -17 mms (rising)
As the flow rate is small we will use a vertical cylindrical vessel
The decanter vessel is sized on the basis that the velocity of the continuous phase must be less than settling velocity of the droplets of the dispersed phase Plug flow is assumed and the velocity of the continuous phase calculated using the area of the interfacemicroc =Lclt microdAiWhere microd = settling velocity of the dispersed phase droplets msmicroc = velocity of the continuous phase msLc = continuous phase volumetric flow rate msup3sAi = area of the interface msup2
29 of 72
Lc = 570311 X 1 99704 3600
= 00015889 msup3s
Ai=Lc = 00015889 microc 00017
= 0935817588 msup2
For a vertical cylindrical decanterAi = prodrsup2
r = 0935817588 prodr = 0545835318 m
Diameter= 1091670637 m
Taking the height as twice the diameter a reasonable value for a cylinder
Height = 2183341274 m
The position of the interface should be such that the band of droplets that collect at the interface waiting to coalesce and cross the interface does not extend to the bottom (or top) of the vessel The depth of the dispersion band is a function of the liquid flow rate and the interfacial area A value of to per cent of the decanter height is usually taken for the design purposes
Take the dispersion band as 10 per cent of the height = 021833mThe residence time of the droplets in the dispersion band = 021833 = 021833microd 00017 =1285926 s (approx 2 min)
This is satisfactory time a time of 2 to 5 min is normally recommended Thus the size of the water (continuous heavy phase) droplets that could be entrained with benzene (light phase) will be
Velocity of benzene phase = 4543812 X 1 X 1 873811 3600093581
=0001543511 ms =1543511mms
30 of 72
So from equation ( ) So the entrained droplet size will be =00015435 X 18 X 0000604 frac12 981 X (99704-873812)
=00001178 m=1178 microm
which is satisfactory below 150 microm
Piping arrangement
To minimize entrainment by the jet of liquid entering the vessel the inlet velocity for a decanter should keep below 1 ms
The velocity from static mixer= 066 ms
Flow rate= 4543812 + 570311 X 1 87381 99704 3600
= 0003033345msup3s
Area of pipe= flow ratevelocity
= 0003033345066
= 0004554572msup2
Pipe diameter =0004554572 x 4prod
= 0076158749 m =29983 inch (approx 3 in)
31 of 72
32 of 72
33 of 72
34 of 72
35 of 72
36 of 72
37 of 72
PROJECT II
CALULATING THE DEW POINT
This project is about the study and evaluation of the performance of the compressors in the Hydrobon section of the LAB plant which is installed to optimize the purity of hydrogen coming from the product separators The compressors in this section include recycle gas compressor and make-up gas compressorThe purity of hydrogen can be increased upto 90
This project will give the company an overall view of this loop The plant is running well about its installed capacity(131-140) The company wants to retain the purity level of nearly 90 for hydrogen even after operating above installed capacity Hence the current project will give the company an idea of the current hydrogen quality(purity) which is obtained and give an idea about changes if any to be made to existing process set-up
HYDROBON REACTOR
Hydrobon reactor is designed to remove contaminants present in the raw kerosene without changing the boiling range The hydrocarbon is passed through a 2 bed reactor feed with S 12 catalyst through a feed effluent exchanger and charge heater which maintain the required reaction temperature(310 c) The reaction required hydrogen gas which is supplied from pacol net gas generated from back end and tattoray hydrogen from PX plantThe reaction charge is heated to the reaction temperature in the charge heater enters the reactor from the top and is distributed over the catalyst bed Catalytic hydrogenation takes place in the reactor The impurities react with hydrogen and form salts which are subsequently separated and finally removed in sour water stripper The reactor effluents after separation is fed to the product stripper to remove lighters and hydrotreated kerosene is fed to molex unit The sulfur and nitrogen levels are reduced to 1 ppm or less
PARAMETERS DESIGN ACTUALPlant load() 100 115Hydrobon feed rate(mthr) 58 60Temperature 416 310Pressure (kgcm2 g) 822 62H2HC ratio 385 460Recycle hydrogen purity(mole)
75 min 95
Hydrobon feed specificationa Bromine
index(mg100gm)800 800
38 of 72
b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
39 of 72
HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
40 of 72
4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
41 of 72
FLOW DIAGRAM OF HYDROBON SECTION
42 of 72
Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
43 of 72
nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
44 of 72
Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
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DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
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ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
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Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
49 of 72
Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
50 of 72
Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
51 of 72
=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
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Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
53 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
54 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
55 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
LAB (Linear Alkyl Benzene) Process Overview
Introduction
The linear alkylbenzenes produced from C10-C13 linear olefins are useful detergent intermediates and can be readily sulfonated to yield linear alkylbenzensulfonates
HF acid catalystC10C13 olefins + Benzene Linear alkyl benzene (LAB)
SulfonationLinear Alkyl benzene (LAB) LAB sulfonates
These compounds constitute the ldquoactiverdquo ingredients of many household detergents They are surface-active compounds (surfactants) which are combined with various builders (often inorganic salts) to make up a detergent formula
BuildersLAB sulfonates House hold Detergents
Typical Detergent formulation
LAB sulfonates 25wt
Sodium tripolyphosphate 40 wt
Sodium silicate 10 wt
Sodium sulfate 16 wt
Water 8 wt
Carboxymethylcellulose 1 wt
7 of 72
History
During 1940rsquos and 1950rsquos the detergent market was primarily captured by dodecylbenzene (DDB) a product formed by alkylation of Benzene with propylene tetramer It was found that detergent formed by this was giving poor biodegradability of detergent
Propylene tetramer + Benzene Dodecylbenzene (DDB) (Low biodegradability)
Thus LAB introduced in early 60rsquos have substantially replaced this DDB which is having good biodegradability (gt95)
Process Description
Brief Overview
LAB manufacturing process is a technology patented by UOP Inc (Universal oil Product)
The LAB plant is divided into two parts called
a) Front Endb) Back End
In Front End Normal paraffin which is raw material for LAB is extracted from kerosene feed (UOP Molex unit)
UOP Molex unit Feed kerosene N paraffin (C10- C13) (Normal amp (Raw material for LAB) Non-normal paraffin)
8 of 72
In Back End this Normal paraffin is dehydrogenated to linear olefins (UOP Pacol unit)The linear olefins are then alkylated with benzene to LAB
UOP Pacol unit(Dehydrogenation)N paraffin (C10- C13) Linear Olefins (C10-C13)
HF acid catalystC10C13 olefins + Benzene Linear alkyl benzene (LAB)
Detail Description of Process
1) Front EndAs described earlier Normal paraffin (C10 to C13) is extracted from kerosene feed by UOP molex process The kerosene feed stock contains various carbon-chained compounds ranging from C7 to C17 This kerosene is processed in front end in series of processes they are
a) Prefractionation b) Hydrobon c) Molex
a) PREFRACTIONATION
The kerosene is fed to Prefractionation unit where heart cut kerosene of carbon chain C 10 to C14
is separated in two distillation columns in series
1) Stripper column
In this distillation column lighter compounds less than C10 are separated from top as
distillate The bottoms from the column is fed to second distillation column called
Rerun column
2) Rerun columnIn this column Heart cut kerosene of C10 to C14 is separated from top as distillate
9 of 72
STRIPPER
RERUN
Heart cut Kerosene (C10 to C14)
Light Kerosene
Feed kerosene
Heavy kerosene
b) HYDROBON
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit The catalyst used in Hydrobon reactor is S12 (Nickel ndashmolybdenumumoxide on alumina)
The heartcut kerosene from Prefractionation rerun column overhead is fed to this Hydrobon unit to remove sulfur nitrogen below 1 ppm This reaction is called as hydrotreating In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor
10 of 72
C-C-C-C-SH + H2 C-C-C-C + H2SOrganic sulfur(Mercaptan)
+ H2 C-C-C-C-C + NH3 N Nitrogen compound (Pyridine)
The reaction temperature is maintained at 310DegC while pressure is maintained at 65kgcm2g
The reactor temperature is maintained by charge heater where heat input is given by firing fuel
oil A recycle gas compressor and makeup gas compressor maintains the reactor pressure to 65
kgcm2g The H2 required for reaction is compressed in makeup gas compressor upto reactor
pressure
At reaction temperature cracking also takes place where some lighter (ltC10) are formed To
separate this the reactor effluent is passed to distillation column called Product Stripper The off
gases separated in stripper are burnt in heater as fuel
The H2S and NH3 formed in reaction form the ammonium sulfide salts The water is injected in
reactor effluent to prevent the deposition of salts that can corrode and foul the coolers The
desolved salts in water are further treated in sour water stripper to separate H2S and NH3 which
are burnt in heater as off gas
11 of 72
ProductSeparator
PRODUCT
STR
Lighters andOff gases
H2 from makeup gas compressor
Hydrobon reactor
To Molex unit
Charge heater
Feed from Prefractionation
Block Diagram of Hydrobon unit
c) MOLEX Molex process is effective method of separating normal paraffin from stream of hydrocarbon having normal and non-normal by physical selective adsorption process
The process uses solid adsorbent (Molecular sieve) where normal paraffin of straight chains are adsorbed in selective pores and non normal of branched chain are adsorbed in non selective pores
The adsorbed normal paraffin are then desorbed by normal pentane while non normal are desorbed by iso-octane
12 of 72
CHAMBER
CHAMBER
ROTARY VALVE
EXTRACT
RAFFINATE
Normal paraffin Non Normal
There are two adsorption chambers with 24 beds The process simulates countercurrent contact between fixed bed adsorbent and feed stream This simulation is done by flow directing device called ldquoRotary valverdquo
The separated streams from Molex chambers containing normal paraffin (Extract) and non normal (Raffinate) are fed to two distillation columns a) Extract column and b) Raffinate column In both distillation columns desorbent is separated from top and sidecut and recycled for desorption While bottom product of Extract column is Normal paraffin send to storage
E R
F
D
13 of 72
STRIPPER
RERUN
Heart cut Paraffin (C10 to C13)
Light NP
Feed NP
Heavy NP
2) Back EndAs described earlier Linear alkyl benzene (LAB) is produced from linear olefins by UOP detergent alkylation process The raw material normal paraffin of C10 to C14 from front end is processed in back end in series of processes they are
a) Prefractionation b) Pacol c) Alkylation
a) PREFRACTIONATION The normal paraffin of C10 to C14 carbon range is separated to Normal paraffin of C10 to C13 carbon range in two distillation columns in series
1) Stripper column In this distillation column lighter compound (if any) and partly C10 paraffin is removed as light normal paraffin (LNP) from top This LNP is sold in market as byproduct The bottoms is send to Rerun column
2) Rerun ColumnIn this column heartcut paraffin (C10 to C13) is separated from top as distillate The bottoms containing mainly C14 paraffin is sold in market as heavy normal paraffin (HNP) as byproduct
14 of 72
b) PACOL (Paraffin converted to olefin)
The normal paraffin of carbon range C10 to C13 is converted to linear olefins of carbon range C10 to C13 by Dehydrogenation reaction in UOP Pacol process
The catalyst used in reactor is alumina based platinum catalyst
Platinum catalyst
CH3-C-C-C-CH3 CH3 - C = C ndash C ndash CH3 + H2
N paraffin Linear Mono olefins
There are some side reactions takes places in Pacol they are
CH3 - C = C ndash C ndash CH3 CH3 - C = C = C ndash CH3 + H2
Linear Mono olefins Linear Di olefins
CH3 - C = C = C ndash CH3 Aromatics + H2
Linear Di olefins
As it is dehydrogenation reaction H2 gas is separated from reactor effluent in contact condenser and send to Front End for Hydrobon makeup gas compressor
Cracking also takes place in reactor where ltC10 paraffin and olefins are formed which is removed in distillation column called Pacol stripper The gas separated in stripper is burnt in heater as off gases
The reaction temperature is 470 to 495 DegC while pressure is kept low at 13 kgcm2g
The life of pacol catalyst is about 30 to 40 days As life of the catalyst is low there are two pacol reactors for continuous running of the plant
The conversion of paraffin is about 12 to 13
15 of 72
ContactCondenser
PACOL
STPR
Lighters andOff gases
Pacol reactor
To Alkylation
Charge heater
Normal ParaffinFeed
H2 to front end
DEFINE UNIT
The main purpose of this unit is to increase overall yield of LAB The Diolefins formed in Pacol reaction is converted to Mono olefins and normal paraffin thereby generating more LAB and lesser byproducts
The catalyst used in this reactor is Nickel based on alumina
Nickel catalyst
Diolefins + H2 Mono olefins
Diolefins + H2 Normal Paraffin
The reaction temperature is 180 DegC and pressure is 140 Kgcm2g
Block Diagram of Pacol Unit
16 of 72
IMIXER
2MIXER
HFSTRIPPER
C) ALKYLATION
As described earlier linear olefins (C10 to C13) are alkylated in this unit to form Linear alkyl Benzene (LAB) in presence of HF acid catalyst
The mono olefins are conveterd to Linear alkyl benzene (LAB) while diolefins are conveterd to Heavy alkyl Benzene (HAB) The aromatics are extracted in counter current extraction of HF acid and are separated in distillation column called Acid regenerators
HF acid catalyst
R- CH = CH ndashCH2 ndash Rrsquo + Benzene R-CH-CH2-CH2-Rrsquo
M Olefins
Where R and Rrsquo are alkyl groups (CH3) LAB
R-CH=CH-CH=CH-Rrsquo + 2 Benzene Heavy alkyl benzene
Di olefins HAB
The reaction is instantaneous and carried through a two stage mixer settler system The reactor section effluent is then processed in series of distillation columns where excess Benzene Paraffin LAB and byproduct Heavy alkyl benzene (HAB) gets separated
The separated benzene is recycled back to HF alkylation reactor while separated Paraffin is recycled to Pacol reactor for reaction The product Linear alkyl benzene (LAB) and byproduct Heavy alkyl benzene (HAB) are send to storage
The aromatics and non-normal which are formed in Pacol reaction are extracted in HF reaction unit by counter current extraction of HF acid as POLYMER This polymer is separated in Acid regenerators and then neutralized with KOH and send to storage
Block Diagram of Alkylation process
17 of 72
PROCESS INPUTS amp OUTPUTS
18 of 72
As described earlier plant is divided into two sections
a) Front End for Normal paraffin production from Keroseneb) Back End for Linear alkyl Benzene (LAB) production from N paraffin
The raw material kerosene is supplied to the plant from two sources
a) From Bharat Petroleum Corp Ltd Chembur (BPCL) via 55 Km pipelineb) From Reliance Petroleum Ltd Jamnagar via Shipping
The light kerosene heavy kerosene and Raffinate from front end are combined and send as return kerosene via pipeline or shipping to either BPCL or to RPL Jamnagar
The manufacturing of LAB is done in two grades
a) Domestic grade (Molecular weight 235 to 239)b) Export grade (Molecular weight 239 to 240)
The byproducts of LAB plant are
a) Light Normal paraffinb) Heavy normal paraffinc) Heavy alkyl Benzened) Tar polymer
Installed Capacities
A) For Normal Paraffin 115000 MT Highest prod 126596 MT in year 2001-2002
B) For LAB 100000 MT Highest prod 112484 MT in year 1999-2000
Plant load
A) For Normal Paraffin 117
B) For LAB 120 Production per day
A) For Normal Paraffin 330 MT day (Avrg)
B) For LAB 324 MTday (Avrg)
Customers
19 of 72
1) The Normal paraffin produced in LAB plant is normally used for captive consumption for producing LAB
2) The main customer of LAB is Ms Hindustan Lever and Procter amp Gamble Ltd and their subsidiary
3) The LAB is exported to Europe American African and Asian countries4) The light and Heavy normal paraffin is used to manufacture Chlorinated Paraffin Wax5) Heavy alkyl Benzene is used as lubricants in oil industry
Utility system in LAB plant
Hot oil system
There are two Hot oil Heaters available in LAB plant one for Front End and other is for Back End The Heaters are fired with furnace oil LSHS and off gases from process
The Hot oil (Dow Therm) which is thermic fluid is heated in these Hot oil heaters
The all heat inputs to the column preheater are given by circulating Hot oil at supply temperature of 330 DegC
Effluent System
The effluent generated in LAB plant mainly constitute
a) Fluoride Maximum limit lt 10 ppmb) Oil Maximum limit lt 10 ppm
For reduction of fluoride in effluent water LAB plant have two neutralisation basins where effluent from HF area is collected and then reacted with Lime (CaCO3) to reduce fluoride content below 10ppm
For reduction of oil in effluent water LAB plant have CPI separator installed to separate oil from effluent water The oil separated is send to Slope oil storage
In addition to this there is hydrocarbon pit installed in front end to collect pump and filter drains which is being blended in return kerosene to reduce oil load in effluent systemThere all oil collection pits installed in storm water channels to avoid oil going into the river via gates
20 of 72
Cooling water systemFor cooling the final products Byproducts to normal ambient temperatures the products byproducts are cooled in coolers The cooling media used is water There are three cooling towers installed in LAB planta) HF cooling tower it is separate cooling tower to avoid HF ingrace in coolers in non-HF
areab) Front End Cooling towerc) Back End cooling tower
Fin Fan coolers The distillation columns overheads are condensed in air-cooled fin fan coolers The advantage of these coolers over water-cooled coolers is low operating cost
Safety measures taken in LAB Plant
1) Safety Interlocks for tripping the operation of equipments in case process variables touches maximum allowable value
2) Flare system for burning excess gases from process3) Infra red detection system for Pacol Reactor and Hot pumps 4) Hydrocarbon detection system for detecting hydrocarbon leakages5) H2S detection system and siren for detecting H2S gas leakages 6) HF Detection system for detecting HF leakages7) Schedule HF leak testing of HF flanges8) Application of HF detection paints to all HF flanges to detect HF leak by decolouration9) Schedule Thickness survey of pipelines in HF area 10) Fire water sprinkler system for HF vessels Columns and pumps11) Fire water sprinkler system for Hot oil pumps12) Yellow boundary marking of HF area where personal protective equipments (PPErsquos) are
mandatory 13) Personal protective equipments (PPErsquos) for HF area Different types of PVC suits are defined
for different types of jobs ( A B C and D type)14) Separate breathing air reciprocating compressor for breathing air for C and D type PVC
suits in case of eemergency15) KOH scrubbing for venting from all HF equipments so that HF will not release into the
flare16) Daily Benzene monitoring with dragger tubes to detect any Benzene leaks from process17) Close draining system of HF and Benzene
21 of 72
PROJECT ndashI
The project is about developing a ldquoBENZENE-WATER WASHrdquo system to remove the impurities coming with fresh benzene that enters into benzene stripper and effects thefin-fan cooler The project is about developing such a scheme which will remove these impurities before entering the benzene stripper to eliminate the failure of fin-fan cooler
The scheme should also be such that it should not reduce the efficiency of the equipment and should be cost-effective
What is Benzene stripper
The high volatility of water dissolved in hydrocarbons is used in this column to obtain water-free benzene in the column bottoms which also removes any dissolved oxygen or non-condensibles in the benzene or off spec feeds Makeup benzene is fed to the overhead receiver on level control reset by the overhead receiver level controller It is refluxed via the overhead pump on flow control reset by the column bottom level controller and sent to the reaction section by the bottoms pump via the benzene stripper feedbottoms exchanger on flow control which is reset by the benzene column receiver level controller The benzene stripper receiver floats on the flare and is sized big enough to allow enough settling time for the water There is a small nitrogen flow via a conservation vent into the receiver vapor flare to maintain a slight nitrogen purge Water is collected in the boot and drained periodically whenever there is a boot high alarm Maintain a visible benzene water interface in the boot sight glass The benzene at the column bottom normally has a water content of less than 20ppm actually much lower if the column is operated well A moisture analyzer alarm high is provided The heat input to the column is provided by a hot oil reboiler with the hot oil flow controlled Off-spec material from the off-spec tank is normally rerun via the benzene stripper coming into the column receiver
What is the Issue
The benzene stripper column overheads are condensed in air-cooler (fin-fan coolers EC-301)The advantage of using this fin-fan cooler is the low operating cost no space constraint as are not on ground level etc This tube-bundle was failing at a frequency of once in a span of two years Failure analysis study was carried out and found that there are some impurities coming along with fresh benzene which are forming acidic solution after condensing in fin-fan This acidic solution formed was causing the repeated failure of tube-bundle
Water dosing was started upstream of the fin-fan bundle to dissolve out the impurities or to neutralize the acidic solution so that tubes can be saved This practice was started in 2008 Even after this modification the failures and continue and its difficult to analyze that what type of impurities are coming with benzene
22 of 72
So to eliminate this problem a scheme has been plotted to design a benzene scrubbing system This will be basically washing of benzene with DM water to remove the impurities before it enters the benzene stripper
The schematic diagram of this system is shown below
The scheme consists of a static mixture for mixing benzene and water for a particular residence time and at a particular velocity as required A gravity settler is for separating benzene and water on the basis of density difference
23 of 72
STATIC MIXER
This mixing device has no moving parts is simple and its cost can be quite reasonable when compared to mechanical driven mixers Static or motionless mixers are relatively new development and have proven to be effective for many specific and valuable process application It is useful for a wide range of viscosity fluids particularly useful in liquid-liquid mixing and also for some gas-liquid dispersion
The concept of motionless mixers is to achieve a uniform composition and temperature distribution in fluids flowing through the device The concept is build around a stationary rigid element placed in a pipe or cylinder that uses the energy of fluid flowing past to produce the mixing The unit becomes more efficient by adding additional static elements causing the flowing fluid elements to split rearrange recombine and split again to repeat the process lsquoxrsquo times for a uniform or homogeneous flowing stream is produced at discharge
Principle of operation
The static mixer unit is a series of fixed helical elements enclosed within a tubular housing
LIQUID ndash LIQUID SEPARATION(Decanters)
Separation of two liquid phases immiscible or partially miscible liquids is a common requirement in the process industries It is also frequently necessary to separate small quantities of entrained water from process streams The simplest form of equipment used to separate liquid phases is the gravity settling tank the decanter Various proprietary equipment is also used to promote coalescence and improve separation in difficult systems or where emulsions are likely to form Centrifugal separators are also used
Decanters (settlers)
Decanters are used to separate liquids where there is a sufficient difference in density between the liquids for the droplets to settle readily Decanters are essentially tanks which give sufficient residence time for the droplets of the dispersed phase to rise (or settle ) to the interface between the phases and coalesce
In an operating decanter there will be three distinct zones or bands clear heavy liquid separating dispersed liquid (the dispersion zone) and clear light liquid The position of the interface can be controlled with or without the use of instruments by use of a siphon take-off for the heavy liquid
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Vertical decanter
The height of the take-off can be determined by making a pressure balance Neglecting friction loss in the pipes the pressure exerted by the combined height of the heavy and light liquid in the vessel must be balanced by the height of the heavy liquid in the take-off leg
(z1-z3)Ρ1g + z3 Ρ2g= z2 Ρ2g
z2 = (z1-z3) Ρ1 + z3 (1)Ρ2
WhereZ1= height from datum to light liquid overflow m Z2=height from datum to heavy liquid overflow m Z3=height from datum to interface m Ρ1=density of the light liquid kgmsup3 Ρ2=density of the heavy liquid kg msup3
The height of the liquid interface should be measured accurately when the liquid densities are close when one component is present only in small quantities or when the throughput is very small A typical scheme for the automatic control of the interface using a level instrument that can detect the position of the interface is shown in the diagram below Where one phase is present only in small amounts it is often recycled to the decanter feed to give more stable operation
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CALCULATIONS
STATIC MIXER DESIGN
Required data
1 Physical properties of materials Density kgmsup3
Viscosity Pas = 0001Cp
2 Pressure drop Pressure drop in static mixer is best described by comparison with pipe flow
3 Geometrical parameters Diameter m
Type of static mixer constant (k)
Length (l) m
4 Process variables
Flow rate msup3s TemperaturedegC Pressure bar
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Pressure drop calculation
a) Velocity (v)
V = Qπ4 Dsup2
b) Reynoldsrsquos number(Re)
Re= dvρμ
c) Pressure drop (Δp)For Re lt50 Δp =k1x μ x l xQd dsup3
k1= laminar flow constant
For Re gt10sup3 Δp =k2 x ρ x l x vsup2d 2
= k2 x Q x l x 8 x Qsup2d prodsup2 d⁴
k2= turbulent flow constant
Pipe diameter Flow seems to be turbulent as both the materials (B2+ H2O) are not viscous
D =39Q ⁰ ⁴⁵ ρ sup1sup3⁰
Q =52 + 572 = 1092msup3hr = 303 x 10macrsup3msup3s= 38564 ftsup3hr
Ρ = 926328 kgmsup3 =57828 lbftsup3
D =39 x Q ⁰ ⁴⁵ x ρ sup1sup3⁰
D =39 x (38564) ⁰ ⁴⁵ x (57828) sup1sup3⁰ 3600
D= 24 inch = 25 inch = 00635m
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Velocity(v)
V =4 Q proddsup2
= 303 x 10macrsup3 msup3s x 4 314 x (00635)sup2
= 0957 ms (approx 1ms)
Reynoldrsquosnumber(Re)
Re = dvρ Μ = 00635 x 1 x 926328 0572
Re =103 x 10⁵
Thus the flow is highly turbulent
Flow regime Reynoldrsquos no(Re)
No of element No of elements to add if viscosity ratio between fluids exceeds 10001
No of elements to add if volumetric ratio between fluids exceeds 1001
Laminar lt1 24 6 61-10 18 6 611-50 14 6 651-100 12 6 6101-500 10 6 6
Transitional 501-1000 8 4 41001-2000 6 4 4
Turbulent 2001-5000 4 2 25001+ 2 2 2
Thus from the above table the mixer will have 2 elements
The mixer length will be based on the number of elements required An approximate length can be determined by multiplying the number of elements by 15
Mixer length = 15 x 2 =3
28 of 72
For turbulent flow applications it is generally recommended that a minimum velocity of 10 ftsec be maintained
V= 0408 x QDsup2 = 0408 x 4813sup2 = 218 ftsec =066 ms
DECANTER DESIGN
Benzene Water
Flow rate (msup3h) 52 572
Flow rate (kgh) 4543812 570311
Density (kgmsup3) 87381 99704
Viscosity (Pas) 0000604 000089
Take Dd = 150microm
microd = (150 Х 10ˉ⁶)sup2 Х 981 Х (87381-99704) 18 Х 000089
microd = -169787 Х 10ˉsup3 ms = -17 mms (rising)
As the flow rate is small we will use a vertical cylindrical vessel
The decanter vessel is sized on the basis that the velocity of the continuous phase must be less than settling velocity of the droplets of the dispersed phase Plug flow is assumed and the velocity of the continuous phase calculated using the area of the interfacemicroc =Lclt microdAiWhere microd = settling velocity of the dispersed phase droplets msmicroc = velocity of the continuous phase msLc = continuous phase volumetric flow rate msup3sAi = area of the interface msup2
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Lc = 570311 X 1 99704 3600
= 00015889 msup3s
Ai=Lc = 00015889 microc 00017
= 0935817588 msup2
For a vertical cylindrical decanterAi = prodrsup2
r = 0935817588 prodr = 0545835318 m
Diameter= 1091670637 m
Taking the height as twice the diameter a reasonable value for a cylinder
Height = 2183341274 m
The position of the interface should be such that the band of droplets that collect at the interface waiting to coalesce and cross the interface does not extend to the bottom (or top) of the vessel The depth of the dispersion band is a function of the liquid flow rate and the interfacial area A value of to per cent of the decanter height is usually taken for the design purposes
Take the dispersion band as 10 per cent of the height = 021833mThe residence time of the droplets in the dispersion band = 021833 = 021833microd 00017 =1285926 s (approx 2 min)
This is satisfactory time a time of 2 to 5 min is normally recommended Thus the size of the water (continuous heavy phase) droplets that could be entrained with benzene (light phase) will be
Velocity of benzene phase = 4543812 X 1 X 1 873811 3600093581
=0001543511 ms =1543511mms
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So from equation ( ) So the entrained droplet size will be =00015435 X 18 X 0000604 frac12 981 X (99704-873812)
=00001178 m=1178 microm
which is satisfactory below 150 microm
Piping arrangement
To minimize entrainment by the jet of liquid entering the vessel the inlet velocity for a decanter should keep below 1 ms
The velocity from static mixer= 066 ms
Flow rate= 4543812 + 570311 X 1 87381 99704 3600
= 0003033345msup3s
Area of pipe= flow ratevelocity
= 0003033345066
= 0004554572msup2
Pipe diameter =0004554572 x 4prod
= 0076158749 m =29983 inch (approx 3 in)
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PROJECT II
CALULATING THE DEW POINT
This project is about the study and evaluation of the performance of the compressors in the Hydrobon section of the LAB plant which is installed to optimize the purity of hydrogen coming from the product separators The compressors in this section include recycle gas compressor and make-up gas compressorThe purity of hydrogen can be increased upto 90
This project will give the company an overall view of this loop The plant is running well about its installed capacity(131-140) The company wants to retain the purity level of nearly 90 for hydrogen even after operating above installed capacity Hence the current project will give the company an idea of the current hydrogen quality(purity) which is obtained and give an idea about changes if any to be made to existing process set-up
HYDROBON REACTOR
Hydrobon reactor is designed to remove contaminants present in the raw kerosene without changing the boiling range The hydrocarbon is passed through a 2 bed reactor feed with S 12 catalyst through a feed effluent exchanger and charge heater which maintain the required reaction temperature(310 c) The reaction required hydrogen gas which is supplied from pacol net gas generated from back end and tattoray hydrogen from PX plantThe reaction charge is heated to the reaction temperature in the charge heater enters the reactor from the top and is distributed over the catalyst bed Catalytic hydrogenation takes place in the reactor The impurities react with hydrogen and form salts which are subsequently separated and finally removed in sour water stripper The reactor effluents after separation is fed to the product stripper to remove lighters and hydrotreated kerosene is fed to molex unit The sulfur and nitrogen levels are reduced to 1 ppm or less
PARAMETERS DESIGN ACTUALPlant load() 100 115Hydrobon feed rate(mthr) 58 60Temperature 416 310Pressure (kgcm2 g) 822 62H2HC ratio 385 460Recycle hydrogen purity(mole)
75 min 95
Hydrobon feed specificationa Bromine
index(mg100gm)800 800
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b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
39 of 72
HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
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4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
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FLOW DIAGRAM OF HYDROBON SECTION
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Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
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nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
44 of 72
Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
45 of 72
DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
47 of 72
ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
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Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
49 of 72
Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
50 of 72
Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
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=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
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Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
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Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
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Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
55 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
History
During 1940rsquos and 1950rsquos the detergent market was primarily captured by dodecylbenzene (DDB) a product formed by alkylation of Benzene with propylene tetramer It was found that detergent formed by this was giving poor biodegradability of detergent
Propylene tetramer + Benzene Dodecylbenzene (DDB) (Low biodegradability)
Thus LAB introduced in early 60rsquos have substantially replaced this DDB which is having good biodegradability (gt95)
Process Description
Brief Overview
LAB manufacturing process is a technology patented by UOP Inc (Universal oil Product)
The LAB plant is divided into two parts called
a) Front Endb) Back End
In Front End Normal paraffin which is raw material for LAB is extracted from kerosene feed (UOP Molex unit)
UOP Molex unit Feed kerosene N paraffin (C10- C13) (Normal amp (Raw material for LAB) Non-normal paraffin)
8 of 72
In Back End this Normal paraffin is dehydrogenated to linear olefins (UOP Pacol unit)The linear olefins are then alkylated with benzene to LAB
UOP Pacol unit(Dehydrogenation)N paraffin (C10- C13) Linear Olefins (C10-C13)
HF acid catalystC10C13 olefins + Benzene Linear alkyl benzene (LAB)
Detail Description of Process
1) Front EndAs described earlier Normal paraffin (C10 to C13) is extracted from kerosene feed by UOP molex process The kerosene feed stock contains various carbon-chained compounds ranging from C7 to C17 This kerosene is processed in front end in series of processes they are
a) Prefractionation b) Hydrobon c) Molex
a) PREFRACTIONATION
The kerosene is fed to Prefractionation unit where heart cut kerosene of carbon chain C 10 to C14
is separated in two distillation columns in series
1) Stripper column
In this distillation column lighter compounds less than C10 are separated from top as
distillate The bottoms from the column is fed to second distillation column called
Rerun column
2) Rerun columnIn this column Heart cut kerosene of C10 to C14 is separated from top as distillate
9 of 72
STRIPPER
RERUN
Heart cut Kerosene (C10 to C14)
Light Kerosene
Feed kerosene
Heavy kerosene
b) HYDROBON
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit The catalyst used in Hydrobon reactor is S12 (Nickel ndashmolybdenumumoxide on alumina)
The heartcut kerosene from Prefractionation rerun column overhead is fed to this Hydrobon unit to remove sulfur nitrogen below 1 ppm This reaction is called as hydrotreating In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor
10 of 72
C-C-C-C-SH + H2 C-C-C-C + H2SOrganic sulfur(Mercaptan)
+ H2 C-C-C-C-C + NH3 N Nitrogen compound (Pyridine)
The reaction temperature is maintained at 310DegC while pressure is maintained at 65kgcm2g
The reactor temperature is maintained by charge heater where heat input is given by firing fuel
oil A recycle gas compressor and makeup gas compressor maintains the reactor pressure to 65
kgcm2g The H2 required for reaction is compressed in makeup gas compressor upto reactor
pressure
At reaction temperature cracking also takes place where some lighter (ltC10) are formed To
separate this the reactor effluent is passed to distillation column called Product Stripper The off
gases separated in stripper are burnt in heater as fuel
The H2S and NH3 formed in reaction form the ammonium sulfide salts The water is injected in
reactor effluent to prevent the deposition of salts that can corrode and foul the coolers The
desolved salts in water are further treated in sour water stripper to separate H2S and NH3 which
are burnt in heater as off gas
11 of 72
ProductSeparator
PRODUCT
STR
Lighters andOff gases
H2 from makeup gas compressor
Hydrobon reactor
To Molex unit
Charge heater
Feed from Prefractionation
Block Diagram of Hydrobon unit
c) MOLEX Molex process is effective method of separating normal paraffin from stream of hydrocarbon having normal and non-normal by physical selective adsorption process
The process uses solid adsorbent (Molecular sieve) where normal paraffin of straight chains are adsorbed in selective pores and non normal of branched chain are adsorbed in non selective pores
The adsorbed normal paraffin are then desorbed by normal pentane while non normal are desorbed by iso-octane
12 of 72
CHAMBER
CHAMBER
ROTARY VALVE
EXTRACT
RAFFINATE
Normal paraffin Non Normal
There are two adsorption chambers with 24 beds The process simulates countercurrent contact between fixed bed adsorbent and feed stream This simulation is done by flow directing device called ldquoRotary valverdquo
The separated streams from Molex chambers containing normal paraffin (Extract) and non normal (Raffinate) are fed to two distillation columns a) Extract column and b) Raffinate column In both distillation columns desorbent is separated from top and sidecut and recycled for desorption While bottom product of Extract column is Normal paraffin send to storage
E R
F
D
13 of 72
STRIPPER
RERUN
Heart cut Paraffin (C10 to C13)
Light NP
Feed NP
Heavy NP
2) Back EndAs described earlier Linear alkyl benzene (LAB) is produced from linear olefins by UOP detergent alkylation process The raw material normal paraffin of C10 to C14 from front end is processed in back end in series of processes they are
a) Prefractionation b) Pacol c) Alkylation
a) PREFRACTIONATION The normal paraffin of C10 to C14 carbon range is separated to Normal paraffin of C10 to C13 carbon range in two distillation columns in series
1) Stripper column In this distillation column lighter compound (if any) and partly C10 paraffin is removed as light normal paraffin (LNP) from top This LNP is sold in market as byproduct The bottoms is send to Rerun column
2) Rerun ColumnIn this column heartcut paraffin (C10 to C13) is separated from top as distillate The bottoms containing mainly C14 paraffin is sold in market as heavy normal paraffin (HNP) as byproduct
14 of 72
b) PACOL (Paraffin converted to olefin)
The normal paraffin of carbon range C10 to C13 is converted to linear olefins of carbon range C10 to C13 by Dehydrogenation reaction in UOP Pacol process
The catalyst used in reactor is alumina based platinum catalyst
Platinum catalyst
CH3-C-C-C-CH3 CH3 - C = C ndash C ndash CH3 + H2
N paraffin Linear Mono olefins
There are some side reactions takes places in Pacol they are
CH3 - C = C ndash C ndash CH3 CH3 - C = C = C ndash CH3 + H2
Linear Mono olefins Linear Di olefins
CH3 - C = C = C ndash CH3 Aromatics + H2
Linear Di olefins
As it is dehydrogenation reaction H2 gas is separated from reactor effluent in contact condenser and send to Front End for Hydrobon makeup gas compressor
Cracking also takes place in reactor where ltC10 paraffin and olefins are formed which is removed in distillation column called Pacol stripper The gas separated in stripper is burnt in heater as off gases
The reaction temperature is 470 to 495 DegC while pressure is kept low at 13 kgcm2g
The life of pacol catalyst is about 30 to 40 days As life of the catalyst is low there are two pacol reactors for continuous running of the plant
The conversion of paraffin is about 12 to 13
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ContactCondenser
PACOL
STPR
Lighters andOff gases
Pacol reactor
To Alkylation
Charge heater
Normal ParaffinFeed
H2 to front end
DEFINE UNIT
The main purpose of this unit is to increase overall yield of LAB The Diolefins formed in Pacol reaction is converted to Mono olefins and normal paraffin thereby generating more LAB and lesser byproducts
The catalyst used in this reactor is Nickel based on alumina
Nickel catalyst
Diolefins + H2 Mono olefins
Diolefins + H2 Normal Paraffin
The reaction temperature is 180 DegC and pressure is 140 Kgcm2g
Block Diagram of Pacol Unit
16 of 72
IMIXER
2MIXER
HFSTRIPPER
C) ALKYLATION
As described earlier linear olefins (C10 to C13) are alkylated in this unit to form Linear alkyl Benzene (LAB) in presence of HF acid catalyst
The mono olefins are conveterd to Linear alkyl benzene (LAB) while diolefins are conveterd to Heavy alkyl Benzene (HAB) The aromatics are extracted in counter current extraction of HF acid and are separated in distillation column called Acid regenerators
HF acid catalyst
R- CH = CH ndashCH2 ndash Rrsquo + Benzene R-CH-CH2-CH2-Rrsquo
M Olefins
Where R and Rrsquo are alkyl groups (CH3) LAB
R-CH=CH-CH=CH-Rrsquo + 2 Benzene Heavy alkyl benzene
Di olefins HAB
The reaction is instantaneous and carried through a two stage mixer settler system The reactor section effluent is then processed in series of distillation columns where excess Benzene Paraffin LAB and byproduct Heavy alkyl benzene (HAB) gets separated
The separated benzene is recycled back to HF alkylation reactor while separated Paraffin is recycled to Pacol reactor for reaction The product Linear alkyl benzene (LAB) and byproduct Heavy alkyl benzene (HAB) are send to storage
The aromatics and non-normal which are formed in Pacol reaction are extracted in HF reaction unit by counter current extraction of HF acid as POLYMER This polymer is separated in Acid regenerators and then neutralized with KOH and send to storage
Block Diagram of Alkylation process
17 of 72
PROCESS INPUTS amp OUTPUTS
18 of 72
As described earlier plant is divided into two sections
a) Front End for Normal paraffin production from Keroseneb) Back End for Linear alkyl Benzene (LAB) production from N paraffin
The raw material kerosene is supplied to the plant from two sources
a) From Bharat Petroleum Corp Ltd Chembur (BPCL) via 55 Km pipelineb) From Reliance Petroleum Ltd Jamnagar via Shipping
The light kerosene heavy kerosene and Raffinate from front end are combined and send as return kerosene via pipeline or shipping to either BPCL or to RPL Jamnagar
The manufacturing of LAB is done in two grades
a) Domestic grade (Molecular weight 235 to 239)b) Export grade (Molecular weight 239 to 240)
The byproducts of LAB plant are
a) Light Normal paraffinb) Heavy normal paraffinc) Heavy alkyl Benzened) Tar polymer
Installed Capacities
A) For Normal Paraffin 115000 MT Highest prod 126596 MT in year 2001-2002
B) For LAB 100000 MT Highest prod 112484 MT in year 1999-2000
Plant load
A) For Normal Paraffin 117
B) For LAB 120 Production per day
A) For Normal Paraffin 330 MT day (Avrg)
B) For LAB 324 MTday (Avrg)
Customers
19 of 72
1) The Normal paraffin produced in LAB plant is normally used for captive consumption for producing LAB
2) The main customer of LAB is Ms Hindustan Lever and Procter amp Gamble Ltd and their subsidiary
3) The LAB is exported to Europe American African and Asian countries4) The light and Heavy normal paraffin is used to manufacture Chlorinated Paraffin Wax5) Heavy alkyl Benzene is used as lubricants in oil industry
Utility system in LAB plant
Hot oil system
There are two Hot oil Heaters available in LAB plant one for Front End and other is for Back End The Heaters are fired with furnace oil LSHS and off gases from process
The Hot oil (Dow Therm) which is thermic fluid is heated in these Hot oil heaters
The all heat inputs to the column preheater are given by circulating Hot oil at supply temperature of 330 DegC
Effluent System
The effluent generated in LAB plant mainly constitute
a) Fluoride Maximum limit lt 10 ppmb) Oil Maximum limit lt 10 ppm
For reduction of fluoride in effluent water LAB plant have two neutralisation basins where effluent from HF area is collected and then reacted with Lime (CaCO3) to reduce fluoride content below 10ppm
For reduction of oil in effluent water LAB plant have CPI separator installed to separate oil from effluent water The oil separated is send to Slope oil storage
In addition to this there is hydrocarbon pit installed in front end to collect pump and filter drains which is being blended in return kerosene to reduce oil load in effluent systemThere all oil collection pits installed in storm water channels to avoid oil going into the river via gates
20 of 72
Cooling water systemFor cooling the final products Byproducts to normal ambient temperatures the products byproducts are cooled in coolers The cooling media used is water There are three cooling towers installed in LAB planta) HF cooling tower it is separate cooling tower to avoid HF ingrace in coolers in non-HF
areab) Front End Cooling towerc) Back End cooling tower
Fin Fan coolers The distillation columns overheads are condensed in air-cooled fin fan coolers The advantage of these coolers over water-cooled coolers is low operating cost
Safety measures taken in LAB Plant
1) Safety Interlocks for tripping the operation of equipments in case process variables touches maximum allowable value
2) Flare system for burning excess gases from process3) Infra red detection system for Pacol Reactor and Hot pumps 4) Hydrocarbon detection system for detecting hydrocarbon leakages5) H2S detection system and siren for detecting H2S gas leakages 6) HF Detection system for detecting HF leakages7) Schedule HF leak testing of HF flanges8) Application of HF detection paints to all HF flanges to detect HF leak by decolouration9) Schedule Thickness survey of pipelines in HF area 10) Fire water sprinkler system for HF vessels Columns and pumps11) Fire water sprinkler system for Hot oil pumps12) Yellow boundary marking of HF area where personal protective equipments (PPErsquos) are
mandatory 13) Personal protective equipments (PPErsquos) for HF area Different types of PVC suits are defined
for different types of jobs ( A B C and D type)14) Separate breathing air reciprocating compressor for breathing air for C and D type PVC
suits in case of eemergency15) KOH scrubbing for venting from all HF equipments so that HF will not release into the
flare16) Daily Benzene monitoring with dragger tubes to detect any Benzene leaks from process17) Close draining system of HF and Benzene
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PROJECT ndashI
The project is about developing a ldquoBENZENE-WATER WASHrdquo system to remove the impurities coming with fresh benzene that enters into benzene stripper and effects thefin-fan cooler The project is about developing such a scheme which will remove these impurities before entering the benzene stripper to eliminate the failure of fin-fan cooler
The scheme should also be such that it should not reduce the efficiency of the equipment and should be cost-effective
What is Benzene stripper
The high volatility of water dissolved in hydrocarbons is used in this column to obtain water-free benzene in the column bottoms which also removes any dissolved oxygen or non-condensibles in the benzene or off spec feeds Makeup benzene is fed to the overhead receiver on level control reset by the overhead receiver level controller It is refluxed via the overhead pump on flow control reset by the column bottom level controller and sent to the reaction section by the bottoms pump via the benzene stripper feedbottoms exchanger on flow control which is reset by the benzene column receiver level controller The benzene stripper receiver floats on the flare and is sized big enough to allow enough settling time for the water There is a small nitrogen flow via a conservation vent into the receiver vapor flare to maintain a slight nitrogen purge Water is collected in the boot and drained periodically whenever there is a boot high alarm Maintain a visible benzene water interface in the boot sight glass The benzene at the column bottom normally has a water content of less than 20ppm actually much lower if the column is operated well A moisture analyzer alarm high is provided The heat input to the column is provided by a hot oil reboiler with the hot oil flow controlled Off-spec material from the off-spec tank is normally rerun via the benzene stripper coming into the column receiver
What is the Issue
The benzene stripper column overheads are condensed in air-cooler (fin-fan coolers EC-301)The advantage of using this fin-fan cooler is the low operating cost no space constraint as are not on ground level etc This tube-bundle was failing at a frequency of once in a span of two years Failure analysis study was carried out and found that there are some impurities coming along with fresh benzene which are forming acidic solution after condensing in fin-fan This acidic solution formed was causing the repeated failure of tube-bundle
Water dosing was started upstream of the fin-fan bundle to dissolve out the impurities or to neutralize the acidic solution so that tubes can be saved This practice was started in 2008 Even after this modification the failures and continue and its difficult to analyze that what type of impurities are coming with benzene
22 of 72
So to eliminate this problem a scheme has been plotted to design a benzene scrubbing system This will be basically washing of benzene with DM water to remove the impurities before it enters the benzene stripper
The schematic diagram of this system is shown below
The scheme consists of a static mixture for mixing benzene and water for a particular residence time and at a particular velocity as required A gravity settler is for separating benzene and water on the basis of density difference
23 of 72
STATIC MIXER
This mixing device has no moving parts is simple and its cost can be quite reasonable when compared to mechanical driven mixers Static or motionless mixers are relatively new development and have proven to be effective for many specific and valuable process application It is useful for a wide range of viscosity fluids particularly useful in liquid-liquid mixing and also for some gas-liquid dispersion
The concept of motionless mixers is to achieve a uniform composition and temperature distribution in fluids flowing through the device The concept is build around a stationary rigid element placed in a pipe or cylinder that uses the energy of fluid flowing past to produce the mixing The unit becomes more efficient by adding additional static elements causing the flowing fluid elements to split rearrange recombine and split again to repeat the process lsquoxrsquo times for a uniform or homogeneous flowing stream is produced at discharge
Principle of operation
The static mixer unit is a series of fixed helical elements enclosed within a tubular housing
LIQUID ndash LIQUID SEPARATION(Decanters)
Separation of two liquid phases immiscible or partially miscible liquids is a common requirement in the process industries It is also frequently necessary to separate small quantities of entrained water from process streams The simplest form of equipment used to separate liquid phases is the gravity settling tank the decanter Various proprietary equipment is also used to promote coalescence and improve separation in difficult systems or where emulsions are likely to form Centrifugal separators are also used
Decanters (settlers)
Decanters are used to separate liquids where there is a sufficient difference in density between the liquids for the droplets to settle readily Decanters are essentially tanks which give sufficient residence time for the droplets of the dispersed phase to rise (or settle ) to the interface between the phases and coalesce
In an operating decanter there will be three distinct zones or bands clear heavy liquid separating dispersed liquid (the dispersion zone) and clear light liquid The position of the interface can be controlled with or without the use of instruments by use of a siphon take-off for the heavy liquid
24 of 72
Vertical decanter
The height of the take-off can be determined by making a pressure balance Neglecting friction loss in the pipes the pressure exerted by the combined height of the heavy and light liquid in the vessel must be balanced by the height of the heavy liquid in the take-off leg
(z1-z3)Ρ1g + z3 Ρ2g= z2 Ρ2g
z2 = (z1-z3) Ρ1 + z3 (1)Ρ2
WhereZ1= height from datum to light liquid overflow m Z2=height from datum to heavy liquid overflow m Z3=height from datum to interface m Ρ1=density of the light liquid kgmsup3 Ρ2=density of the heavy liquid kg msup3
The height of the liquid interface should be measured accurately when the liquid densities are close when one component is present only in small quantities or when the throughput is very small A typical scheme for the automatic control of the interface using a level instrument that can detect the position of the interface is shown in the diagram below Where one phase is present only in small amounts it is often recycled to the decanter feed to give more stable operation
25 of 72
CALCULATIONS
STATIC MIXER DESIGN
Required data
1 Physical properties of materials Density kgmsup3
Viscosity Pas = 0001Cp
2 Pressure drop Pressure drop in static mixer is best described by comparison with pipe flow
3 Geometrical parameters Diameter m
Type of static mixer constant (k)
Length (l) m
4 Process variables
Flow rate msup3s TemperaturedegC Pressure bar
26 of 72
Pressure drop calculation
a) Velocity (v)
V = Qπ4 Dsup2
b) Reynoldsrsquos number(Re)
Re= dvρμ
c) Pressure drop (Δp)For Re lt50 Δp =k1x μ x l xQd dsup3
k1= laminar flow constant
For Re gt10sup3 Δp =k2 x ρ x l x vsup2d 2
= k2 x Q x l x 8 x Qsup2d prodsup2 d⁴
k2= turbulent flow constant
Pipe diameter Flow seems to be turbulent as both the materials (B2+ H2O) are not viscous
D =39Q ⁰ ⁴⁵ ρ sup1sup3⁰
Q =52 + 572 = 1092msup3hr = 303 x 10macrsup3msup3s= 38564 ftsup3hr
Ρ = 926328 kgmsup3 =57828 lbftsup3
D =39 x Q ⁰ ⁴⁵ x ρ sup1sup3⁰
D =39 x (38564) ⁰ ⁴⁵ x (57828) sup1sup3⁰ 3600
D= 24 inch = 25 inch = 00635m
27 of 72
Velocity(v)
V =4 Q proddsup2
= 303 x 10macrsup3 msup3s x 4 314 x (00635)sup2
= 0957 ms (approx 1ms)
Reynoldrsquosnumber(Re)
Re = dvρ Μ = 00635 x 1 x 926328 0572
Re =103 x 10⁵
Thus the flow is highly turbulent
Flow regime Reynoldrsquos no(Re)
No of element No of elements to add if viscosity ratio between fluids exceeds 10001
No of elements to add if volumetric ratio between fluids exceeds 1001
Laminar lt1 24 6 61-10 18 6 611-50 14 6 651-100 12 6 6101-500 10 6 6
Transitional 501-1000 8 4 41001-2000 6 4 4
Turbulent 2001-5000 4 2 25001+ 2 2 2
Thus from the above table the mixer will have 2 elements
The mixer length will be based on the number of elements required An approximate length can be determined by multiplying the number of elements by 15
Mixer length = 15 x 2 =3
28 of 72
For turbulent flow applications it is generally recommended that a minimum velocity of 10 ftsec be maintained
V= 0408 x QDsup2 = 0408 x 4813sup2 = 218 ftsec =066 ms
DECANTER DESIGN
Benzene Water
Flow rate (msup3h) 52 572
Flow rate (kgh) 4543812 570311
Density (kgmsup3) 87381 99704
Viscosity (Pas) 0000604 000089
Take Dd = 150microm
microd = (150 Х 10ˉ⁶)sup2 Х 981 Х (87381-99704) 18 Х 000089
microd = -169787 Х 10ˉsup3 ms = -17 mms (rising)
As the flow rate is small we will use a vertical cylindrical vessel
The decanter vessel is sized on the basis that the velocity of the continuous phase must be less than settling velocity of the droplets of the dispersed phase Plug flow is assumed and the velocity of the continuous phase calculated using the area of the interfacemicroc =Lclt microdAiWhere microd = settling velocity of the dispersed phase droplets msmicroc = velocity of the continuous phase msLc = continuous phase volumetric flow rate msup3sAi = area of the interface msup2
29 of 72
Lc = 570311 X 1 99704 3600
= 00015889 msup3s
Ai=Lc = 00015889 microc 00017
= 0935817588 msup2
For a vertical cylindrical decanterAi = prodrsup2
r = 0935817588 prodr = 0545835318 m
Diameter= 1091670637 m
Taking the height as twice the diameter a reasonable value for a cylinder
Height = 2183341274 m
The position of the interface should be such that the band of droplets that collect at the interface waiting to coalesce and cross the interface does not extend to the bottom (or top) of the vessel The depth of the dispersion band is a function of the liquid flow rate and the interfacial area A value of to per cent of the decanter height is usually taken for the design purposes
Take the dispersion band as 10 per cent of the height = 021833mThe residence time of the droplets in the dispersion band = 021833 = 021833microd 00017 =1285926 s (approx 2 min)
This is satisfactory time a time of 2 to 5 min is normally recommended Thus the size of the water (continuous heavy phase) droplets that could be entrained with benzene (light phase) will be
Velocity of benzene phase = 4543812 X 1 X 1 873811 3600093581
=0001543511 ms =1543511mms
30 of 72
So from equation ( ) So the entrained droplet size will be =00015435 X 18 X 0000604 frac12 981 X (99704-873812)
=00001178 m=1178 microm
which is satisfactory below 150 microm
Piping arrangement
To minimize entrainment by the jet of liquid entering the vessel the inlet velocity for a decanter should keep below 1 ms
The velocity from static mixer= 066 ms
Flow rate= 4543812 + 570311 X 1 87381 99704 3600
= 0003033345msup3s
Area of pipe= flow ratevelocity
= 0003033345066
= 0004554572msup2
Pipe diameter =0004554572 x 4prod
= 0076158749 m =29983 inch (approx 3 in)
31 of 72
32 of 72
33 of 72
34 of 72
35 of 72
36 of 72
37 of 72
PROJECT II
CALULATING THE DEW POINT
This project is about the study and evaluation of the performance of the compressors in the Hydrobon section of the LAB plant which is installed to optimize the purity of hydrogen coming from the product separators The compressors in this section include recycle gas compressor and make-up gas compressorThe purity of hydrogen can be increased upto 90
This project will give the company an overall view of this loop The plant is running well about its installed capacity(131-140) The company wants to retain the purity level of nearly 90 for hydrogen even after operating above installed capacity Hence the current project will give the company an idea of the current hydrogen quality(purity) which is obtained and give an idea about changes if any to be made to existing process set-up
HYDROBON REACTOR
Hydrobon reactor is designed to remove contaminants present in the raw kerosene without changing the boiling range The hydrocarbon is passed through a 2 bed reactor feed with S 12 catalyst through a feed effluent exchanger and charge heater which maintain the required reaction temperature(310 c) The reaction required hydrogen gas which is supplied from pacol net gas generated from back end and tattoray hydrogen from PX plantThe reaction charge is heated to the reaction temperature in the charge heater enters the reactor from the top and is distributed over the catalyst bed Catalytic hydrogenation takes place in the reactor The impurities react with hydrogen and form salts which are subsequently separated and finally removed in sour water stripper The reactor effluents after separation is fed to the product stripper to remove lighters and hydrotreated kerosene is fed to molex unit The sulfur and nitrogen levels are reduced to 1 ppm or less
PARAMETERS DESIGN ACTUALPlant load() 100 115Hydrobon feed rate(mthr) 58 60Temperature 416 310Pressure (kgcm2 g) 822 62H2HC ratio 385 460Recycle hydrogen purity(mole)
75 min 95
Hydrobon feed specificationa Bromine
index(mg100gm)800 800
38 of 72
b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
39 of 72
HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
40 of 72
4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
41 of 72
FLOW DIAGRAM OF HYDROBON SECTION
42 of 72
Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
43 of 72
nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
44 of 72
Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
45 of 72
DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
46 of 72
DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
47 of 72
ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
48 of 72
Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
49 of 72
Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
50 of 72
Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
51 of 72
=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
52 of 72
Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
53 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
54 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
55 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
In Back End this Normal paraffin is dehydrogenated to linear olefins (UOP Pacol unit)The linear olefins are then alkylated with benzene to LAB
UOP Pacol unit(Dehydrogenation)N paraffin (C10- C13) Linear Olefins (C10-C13)
HF acid catalystC10C13 olefins + Benzene Linear alkyl benzene (LAB)
Detail Description of Process
1) Front EndAs described earlier Normal paraffin (C10 to C13) is extracted from kerosene feed by UOP molex process The kerosene feed stock contains various carbon-chained compounds ranging from C7 to C17 This kerosene is processed in front end in series of processes they are
a) Prefractionation b) Hydrobon c) Molex
a) PREFRACTIONATION
The kerosene is fed to Prefractionation unit where heart cut kerosene of carbon chain C 10 to C14
is separated in two distillation columns in series
1) Stripper column
In this distillation column lighter compounds less than C10 are separated from top as
distillate The bottoms from the column is fed to second distillation column called
Rerun column
2) Rerun columnIn this column Heart cut kerosene of C10 to C14 is separated from top as distillate
9 of 72
STRIPPER
RERUN
Heart cut Kerosene (C10 to C14)
Light Kerosene
Feed kerosene
Heavy kerosene
b) HYDROBON
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit The catalyst used in Hydrobon reactor is S12 (Nickel ndashmolybdenumumoxide on alumina)
The heartcut kerosene from Prefractionation rerun column overhead is fed to this Hydrobon unit to remove sulfur nitrogen below 1 ppm This reaction is called as hydrotreating In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor
10 of 72
C-C-C-C-SH + H2 C-C-C-C + H2SOrganic sulfur(Mercaptan)
+ H2 C-C-C-C-C + NH3 N Nitrogen compound (Pyridine)
The reaction temperature is maintained at 310DegC while pressure is maintained at 65kgcm2g
The reactor temperature is maintained by charge heater where heat input is given by firing fuel
oil A recycle gas compressor and makeup gas compressor maintains the reactor pressure to 65
kgcm2g The H2 required for reaction is compressed in makeup gas compressor upto reactor
pressure
At reaction temperature cracking also takes place where some lighter (ltC10) are formed To
separate this the reactor effluent is passed to distillation column called Product Stripper The off
gases separated in stripper are burnt in heater as fuel
The H2S and NH3 formed in reaction form the ammonium sulfide salts The water is injected in
reactor effluent to prevent the deposition of salts that can corrode and foul the coolers The
desolved salts in water are further treated in sour water stripper to separate H2S and NH3 which
are burnt in heater as off gas
11 of 72
ProductSeparator
PRODUCT
STR
Lighters andOff gases
H2 from makeup gas compressor
Hydrobon reactor
To Molex unit
Charge heater
Feed from Prefractionation
Block Diagram of Hydrobon unit
c) MOLEX Molex process is effective method of separating normal paraffin from stream of hydrocarbon having normal and non-normal by physical selective adsorption process
The process uses solid adsorbent (Molecular sieve) where normal paraffin of straight chains are adsorbed in selective pores and non normal of branched chain are adsorbed in non selective pores
The adsorbed normal paraffin are then desorbed by normal pentane while non normal are desorbed by iso-octane
12 of 72
CHAMBER
CHAMBER
ROTARY VALVE
EXTRACT
RAFFINATE
Normal paraffin Non Normal
There are two adsorption chambers with 24 beds The process simulates countercurrent contact between fixed bed adsorbent and feed stream This simulation is done by flow directing device called ldquoRotary valverdquo
The separated streams from Molex chambers containing normal paraffin (Extract) and non normal (Raffinate) are fed to two distillation columns a) Extract column and b) Raffinate column In both distillation columns desorbent is separated from top and sidecut and recycled for desorption While bottom product of Extract column is Normal paraffin send to storage
E R
F
D
13 of 72
STRIPPER
RERUN
Heart cut Paraffin (C10 to C13)
Light NP
Feed NP
Heavy NP
2) Back EndAs described earlier Linear alkyl benzene (LAB) is produced from linear olefins by UOP detergent alkylation process The raw material normal paraffin of C10 to C14 from front end is processed in back end in series of processes they are
a) Prefractionation b) Pacol c) Alkylation
a) PREFRACTIONATION The normal paraffin of C10 to C14 carbon range is separated to Normal paraffin of C10 to C13 carbon range in two distillation columns in series
1) Stripper column In this distillation column lighter compound (if any) and partly C10 paraffin is removed as light normal paraffin (LNP) from top This LNP is sold in market as byproduct The bottoms is send to Rerun column
2) Rerun ColumnIn this column heartcut paraffin (C10 to C13) is separated from top as distillate The bottoms containing mainly C14 paraffin is sold in market as heavy normal paraffin (HNP) as byproduct
14 of 72
b) PACOL (Paraffin converted to olefin)
The normal paraffin of carbon range C10 to C13 is converted to linear olefins of carbon range C10 to C13 by Dehydrogenation reaction in UOP Pacol process
The catalyst used in reactor is alumina based platinum catalyst
Platinum catalyst
CH3-C-C-C-CH3 CH3 - C = C ndash C ndash CH3 + H2
N paraffin Linear Mono olefins
There are some side reactions takes places in Pacol they are
CH3 - C = C ndash C ndash CH3 CH3 - C = C = C ndash CH3 + H2
Linear Mono olefins Linear Di olefins
CH3 - C = C = C ndash CH3 Aromatics + H2
Linear Di olefins
As it is dehydrogenation reaction H2 gas is separated from reactor effluent in contact condenser and send to Front End for Hydrobon makeup gas compressor
Cracking also takes place in reactor where ltC10 paraffin and olefins are formed which is removed in distillation column called Pacol stripper The gas separated in stripper is burnt in heater as off gases
The reaction temperature is 470 to 495 DegC while pressure is kept low at 13 kgcm2g
The life of pacol catalyst is about 30 to 40 days As life of the catalyst is low there are two pacol reactors for continuous running of the plant
The conversion of paraffin is about 12 to 13
15 of 72
ContactCondenser
PACOL
STPR
Lighters andOff gases
Pacol reactor
To Alkylation
Charge heater
Normal ParaffinFeed
H2 to front end
DEFINE UNIT
The main purpose of this unit is to increase overall yield of LAB The Diolefins formed in Pacol reaction is converted to Mono olefins and normal paraffin thereby generating more LAB and lesser byproducts
The catalyst used in this reactor is Nickel based on alumina
Nickel catalyst
Diolefins + H2 Mono olefins
Diolefins + H2 Normal Paraffin
The reaction temperature is 180 DegC and pressure is 140 Kgcm2g
Block Diagram of Pacol Unit
16 of 72
IMIXER
2MIXER
HFSTRIPPER
C) ALKYLATION
As described earlier linear olefins (C10 to C13) are alkylated in this unit to form Linear alkyl Benzene (LAB) in presence of HF acid catalyst
The mono olefins are conveterd to Linear alkyl benzene (LAB) while diolefins are conveterd to Heavy alkyl Benzene (HAB) The aromatics are extracted in counter current extraction of HF acid and are separated in distillation column called Acid regenerators
HF acid catalyst
R- CH = CH ndashCH2 ndash Rrsquo + Benzene R-CH-CH2-CH2-Rrsquo
M Olefins
Where R and Rrsquo are alkyl groups (CH3) LAB
R-CH=CH-CH=CH-Rrsquo + 2 Benzene Heavy alkyl benzene
Di olefins HAB
The reaction is instantaneous and carried through a two stage mixer settler system The reactor section effluent is then processed in series of distillation columns where excess Benzene Paraffin LAB and byproduct Heavy alkyl benzene (HAB) gets separated
The separated benzene is recycled back to HF alkylation reactor while separated Paraffin is recycled to Pacol reactor for reaction The product Linear alkyl benzene (LAB) and byproduct Heavy alkyl benzene (HAB) are send to storage
The aromatics and non-normal which are formed in Pacol reaction are extracted in HF reaction unit by counter current extraction of HF acid as POLYMER This polymer is separated in Acid regenerators and then neutralized with KOH and send to storage
Block Diagram of Alkylation process
17 of 72
PROCESS INPUTS amp OUTPUTS
18 of 72
As described earlier plant is divided into two sections
a) Front End for Normal paraffin production from Keroseneb) Back End for Linear alkyl Benzene (LAB) production from N paraffin
The raw material kerosene is supplied to the plant from two sources
a) From Bharat Petroleum Corp Ltd Chembur (BPCL) via 55 Km pipelineb) From Reliance Petroleum Ltd Jamnagar via Shipping
The light kerosene heavy kerosene and Raffinate from front end are combined and send as return kerosene via pipeline or shipping to either BPCL or to RPL Jamnagar
The manufacturing of LAB is done in two grades
a) Domestic grade (Molecular weight 235 to 239)b) Export grade (Molecular weight 239 to 240)
The byproducts of LAB plant are
a) Light Normal paraffinb) Heavy normal paraffinc) Heavy alkyl Benzened) Tar polymer
Installed Capacities
A) For Normal Paraffin 115000 MT Highest prod 126596 MT in year 2001-2002
B) For LAB 100000 MT Highest prod 112484 MT in year 1999-2000
Plant load
A) For Normal Paraffin 117
B) For LAB 120 Production per day
A) For Normal Paraffin 330 MT day (Avrg)
B) For LAB 324 MTday (Avrg)
Customers
19 of 72
1) The Normal paraffin produced in LAB plant is normally used for captive consumption for producing LAB
2) The main customer of LAB is Ms Hindustan Lever and Procter amp Gamble Ltd and their subsidiary
3) The LAB is exported to Europe American African and Asian countries4) The light and Heavy normal paraffin is used to manufacture Chlorinated Paraffin Wax5) Heavy alkyl Benzene is used as lubricants in oil industry
Utility system in LAB plant
Hot oil system
There are two Hot oil Heaters available in LAB plant one for Front End and other is for Back End The Heaters are fired with furnace oil LSHS and off gases from process
The Hot oil (Dow Therm) which is thermic fluid is heated in these Hot oil heaters
The all heat inputs to the column preheater are given by circulating Hot oil at supply temperature of 330 DegC
Effluent System
The effluent generated in LAB plant mainly constitute
a) Fluoride Maximum limit lt 10 ppmb) Oil Maximum limit lt 10 ppm
For reduction of fluoride in effluent water LAB plant have two neutralisation basins where effluent from HF area is collected and then reacted with Lime (CaCO3) to reduce fluoride content below 10ppm
For reduction of oil in effluent water LAB plant have CPI separator installed to separate oil from effluent water The oil separated is send to Slope oil storage
In addition to this there is hydrocarbon pit installed in front end to collect pump and filter drains which is being blended in return kerosene to reduce oil load in effluent systemThere all oil collection pits installed in storm water channels to avoid oil going into the river via gates
20 of 72
Cooling water systemFor cooling the final products Byproducts to normal ambient temperatures the products byproducts are cooled in coolers The cooling media used is water There are three cooling towers installed in LAB planta) HF cooling tower it is separate cooling tower to avoid HF ingrace in coolers in non-HF
areab) Front End Cooling towerc) Back End cooling tower
Fin Fan coolers The distillation columns overheads are condensed in air-cooled fin fan coolers The advantage of these coolers over water-cooled coolers is low operating cost
Safety measures taken in LAB Plant
1) Safety Interlocks for tripping the operation of equipments in case process variables touches maximum allowable value
2) Flare system for burning excess gases from process3) Infra red detection system for Pacol Reactor and Hot pumps 4) Hydrocarbon detection system for detecting hydrocarbon leakages5) H2S detection system and siren for detecting H2S gas leakages 6) HF Detection system for detecting HF leakages7) Schedule HF leak testing of HF flanges8) Application of HF detection paints to all HF flanges to detect HF leak by decolouration9) Schedule Thickness survey of pipelines in HF area 10) Fire water sprinkler system for HF vessels Columns and pumps11) Fire water sprinkler system for Hot oil pumps12) Yellow boundary marking of HF area where personal protective equipments (PPErsquos) are
mandatory 13) Personal protective equipments (PPErsquos) for HF area Different types of PVC suits are defined
for different types of jobs ( A B C and D type)14) Separate breathing air reciprocating compressor for breathing air for C and D type PVC
suits in case of eemergency15) KOH scrubbing for venting from all HF equipments so that HF will not release into the
flare16) Daily Benzene monitoring with dragger tubes to detect any Benzene leaks from process17) Close draining system of HF and Benzene
21 of 72
PROJECT ndashI
The project is about developing a ldquoBENZENE-WATER WASHrdquo system to remove the impurities coming with fresh benzene that enters into benzene stripper and effects thefin-fan cooler The project is about developing such a scheme which will remove these impurities before entering the benzene stripper to eliminate the failure of fin-fan cooler
The scheme should also be such that it should not reduce the efficiency of the equipment and should be cost-effective
What is Benzene stripper
The high volatility of water dissolved in hydrocarbons is used in this column to obtain water-free benzene in the column bottoms which also removes any dissolved oxygen or non-condensibles in the benzene or off spec feeds Makeup benzene is fed to the overhead receiver on level control reset by the overhead receiver level controller It is refluxed via the overhead pump on flow control reset by the column bottom level controller and sent to the reaction section by the bottoms pump via the benzene stripper feedbottoms exchanger on flow control which is reset by the benzene column receiver level controller The benzene stripper receiver floats on the flare and is sized big enough to allow enough settling time for the water There is a small nitrogen flow via a conservation vent into the receiver vapor flare to maintain a slight nitrogen purge Water is collected in the boot and drained periodically whenever there is a boot high alarm Maintain a visible benzene water interface in the boot sight glass The benzene at the column bottom normally has a water content of less than 20ppm actually much lower if the column is operated well A moisture analyzer alarm high is provided The heat input to the column is provided by a hot oil reboiler with the hot oil flow controlled Off-spec material from the off-spec tank is normally rerun via the benzene stripper coming into the column receiver
What is the Issue
The benzene stripper column overheads are condensed in air-cooler (fin-fan coolers EC-301)The advantage of using this fin-fan cooler is the low operating cost no space constraint as are not on ground level etc This tube-bundle was failing at a frequency of once in a span of two years Failure analysis study was carried out and found that there are some impurities coming along with fresh benzene which are forming acidic solution after condensing in fin-fan This acidic solution formed was causing the repeated failure of tube-bundle
Water dosing was started upstream of the fin-fan bundle to dissolve out the impurities or to neutralize the acidic solution so that tubes can be saved This practice was started in 2008 Even after this modification the failures and continue and its difficult to analyze that what type of impurities are coming with benzene
22 of 72
So to eliminate this problem a scheme has been plotted to design a benzene scrubbing system This will be basically washing of benzene with DM water to remove the impurities before it enters the benzene stripper
The schematic diagram of this system is shown below
The scheme consists of a static mixture for mixing benzene and water for a particular residence time and at a particular velocity as required A gravity settler is for separating benzene and water on the basis of density difference
23 of 72
STATIC MIXER
This mixing device has no moving parts is simple and its cost can be quite reasonable when compared to mechanical driven mixers Static or motionless mixers are relatively new development and have proven to be effective for many specific and valuable process application It is useful for a wide range of viscosity fluids particularly useful in liquid-liquid mixing and also for some gas-liquid dispersion
The concept of motionless mixers is to achieve a uniform composition and temperature distribution in fluids flowing through the device The concept is build around a stationary rigid element placed in a pipe or cylinder that uses the energy of fluid flowing past to produce the mixing The unit becomes more efficient by adding additional static elements causing the flowing fluid elements to split rearrange recombine and split again to repeat the process lsquoxrsquo times for a uniform or homogeneous flowing stream is produced at discharge
Principle of operation
The static mixer unit is a series of fixed helical elements enclosed within a tubular housing
LIQUID ndash LIQUID SEPARATION(Decanters)
Separation of two liquid phases immiscible or partially miscible liquids is a common requirement in the process industries It is also frequently necessary to separate small quantities of entrained water from process streams The simplest form of equipment used to separate liquid phases is the gravity settling tank the decanter Various proprietary equipment is also used to promote coalescence and improve separation in difficult systems or where emulsions are likely to form Centrifugal separators are also used
Decanters (settlers)
Decanters are used to separate liquids where there is a sufficient difference in density between the liquids for the droplets to settle readily Decanters are essentially tanks which give sufficient residence time for the droplets of the dispersed phase to rise (or settle ) to the interface between the phases and coalesce
In an operating decanter there will be three distinct zones or bands clear heavy liquid separating dispersed liquid (the dispersion zone) and clear light liquid The position of the interface can be controlled with or without the use of instruments by use of a siphon take-off for the heavy liquid
24 of 72
Vertical decanter
The height of the take-off can be determined by making a pressure balance Neglecting friction loss in the pipes the pressure exerted by the combined height of the heavy and light liquid in the vessel must be balanced by the height of the heavy liquid in the take-off leg
(z1-z3)Ρ1g + z3 Ρ2g= z2 Ρ2g
z2 = (z1-z3) Ρ1 + z3 (1)Ρ2
WhereZ1= height from datum to light liquid overflow m Z2=height from datum to heavy liquid overflow m Z3=height from datum to interface m Ρ1=density of the light liquid kgmsup3 Ρ2=density of the heavy liquid kg msup3
The height of the liquid interface should be measured accurately when the liquid densities are close when one component is present only in small quantities or when the throughput is very small A typical scheme for the automatic control of the interface using a level instrument that can detect the position of the interface is shown in the diagram below Where one phase is present only in small amounts it is often recycled to the decanter feed to give more stable operation
25 of 72
CALCULATIONS
STATIC MIXER DESIGN
Required data
1 Physical properties of materials Density kgmsup3
Viscosity Pas = 0001Cp
2 Pressure drop Pressure drop in static mixer is best described by comparison with pipe flow
3 Geometrical parameters Diameter m
Type of static mixer constant (k)
Length (l) m
4 Process variables
Flow rate msup3s TemperaturedegC Pressure bar
26 of 72
Pressure drop calculation
a) Velocity (v)
V = Qπ4 Dsup2
b) Reynoldsrsquos number(Re)
Re= dvρμ
c) Pressure drop (Δp)For Re lt50 Δp =k1x μ x l xQd dsup3
k1= laminar flow constant
For Re gt10sup3 Δp =k2 x ρ x l x vsup2d 2
= k2 x Q x l x 8 x Qsup2d prodsup2 d⁴
k2= turbulent flow constant
Pipe diameter Flow seems to be turbulent as both the materials (B2+ H2O) are not viscous
D =39Q ⁰ ⁴⁵ ρ sup1sup3⁰
Q =52 + 572 = 1092msup3hr = 303 x 10macrsup3msup3s= 38564 ftsup3hr
Ρ = 926328 kgmsup3 =57828 lbftsup3
D =39 x Q ⁰ ⁴⁵ x ρ sup1sup3⁰
D =39 x (38564) ⁰ ⁴⁵ x (57828) sup1sup3⁰ 3600
D= 24 inch = 25 inch = 00635m
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Velocity(v)
V =4 Q proddsup2
= 303 x 10macrsup3 msup3s x 4 314 x (00635)sup2
= 0957 ms (approx 1ms)
Reynoldrsquosnumber(Re)
Re = dvρ Μ = 00635 x 1 x 926328 0572
Re =103 x 10⁵
Thus the flow is highly turbulent
Flow regime Reynoldrsquos no(Re)
No of element No of elements to add if viscosity ratio between fluids exceeds 10001
No of elements to add if volumetric ratio between fluids exceeds 1001
Laminar lt1 24 6 61-10 18 6 611-50 14 6 651-100 12 6 6101-500 10 6 6
Transitional 501-1000 8 4 41001-2000 6 4 4
Turbulent 2001-5000 4 2 25001+ 2 2 2
Thus from the above table the mixer will have 2 elements
The mixer length will be based on the number of elements required An approximate length can be determined by multiplying the number of elements by 15
Mixer length = 15 x 2 =3
28 of 72
For turbulent flow applications it is generally recommended that a minimum velocity of 10 ftsec be maintained
V= 0408 x QDsup2 = 0408 x 4813sup2 = 218 ftsec =066 ms
DECANTER DESIGN
Benzene Water
Flow rate (msup3h) 52 572
Flow rate (kgh) 4543812 570311
Density (kgmsup3) 87381 99704
Viscosity (Pas) 0000604 000089
Take Dd = 150microm
microd = (150 Х 10ˉ⁶)sup2 Х 981 Х (87381-99704) 18 Х 000089
microd = -169787 Х 10ˉsup3 ms = -17 mms (rising)
As the flow rate is small we will use a vertical cylindrical vessel
The decanter vessel is sized on the basis that the velocity of the continuous phase must be less than settling velocity of the droplets of the dispersed phase Plug flow is assumed and the velocity of the continuous phase calculated using the area of the interfacemicroc =Lclt microdAiWhere microd = settling velocity of the dispersed phase droplets msmicroc = velocity of the continuous phase msLc = continuous phase volumetric flow rate msup3sAi = area of the interface msup2
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Lc = 570311 X 1 99704 3600
= 00015889 msup3s
Ai=Lc = 00015889 microc 00017
= 0935817588 msup2
For a vertical cylindrical decanterAi = prodrsup2
r = 0935817588 prodr = 0545835318 m
Diameter= 1091670637 m
Taking the height as twice the diameter a reasonable value for a cylinder
Height = 2183341274 m
The position of the interface should be such that the band of droplets that collect at the interface waiting to coalesce and cross the interface does not extend to the bottom (or top) of the vessel The depth of the dispersion band is a function of the liquid flow rate and the interfacial area A value of to per cent of the decanter height is usually taken for the design purposes
Take the dispersion band as 10 per cent of the height = 021833mThe residence time of the droplets in the dispersion band = 021833 = 021833microd 00017 =1285926 s (approx 2 min)
This is satisfactory time a time of 2 to 5 min is normally recommended Thus the size of the water (continuous heavy phase) droplets that could be entrained with benzene (light phase) will be
Velocity of benzene phase = 4543812 X 1 X 1 873811 3600093581
=0001543511 ms =1543511mms
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So from equation ( ) So the entrained droplet size will be =00015435 X 18 X 0000604 frac12 981 X (99704-873812)
=00001178 m=1178 microm
which is satisfactory below 150 microm
Piping arrangement
To minimize entrainment by the jet of liquid entering the vessel the inlet velocity for a decanter should keep below 1 ms
The velocity from static mixer= 066 ms
Flow rate= 4543812 + 570311 X 1 87381 99704 3600
= 0003033345msup3s
Area of pipe= flow ratevelocity
= 0003033345066
= 0004554572msup2
Pipe diameter =0004554572 x 4prod
= 0076158749 m =29983 inch (approx 3 in)
31 of 72
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PROJECT II
CALULATING THE DEW POINT
This project is about the study and evaluation of the performance of the compressors in the Hydrobon section of the LAB plant which is installed to optimize the purity of hydrogen coming from the product separators The compressors in this section include recycle gas compressor and make-up gas compressorThe purity of hydrogen can be increased upto 90
This project will give the company an overall view of this loop The plant is running well about its installed capacity(131-140) The company wants to retain the purity level of nearly 90 for hydrogen even after operating above installed capacity Hence the current project will give the company an idea of the current hydrogen quality(purity) which is obtained and give an idea about changes if any to be made to existing process set-up
HYDROBON REACTOR
Hydrobon reactor is designed to remove contaminants present in the raw kerosene without changing the boiling range The hydrocarbon is passed through a 2 bed reactor feed with S 12 catalyst through a feed effluent exchanger and charge heater which maintain the required reaction temperature(310 c) The reaction required hydrogen gas which is supplied from pacol net gas generated from back end and tattoray hydrogen from PX plantThe reaction charge is heated to the reaction temperature in the charge heater enters the reactor from the top and is distributed over the catalyst bed Catalytic hydrogenation takes place in the reactor The impurities react with hydrogen and form salts which are subsequently separated and finally removed in sour water stripper The reactor effluents after separation is fed to the product stripper to remove lighters and hydrotreated kerosene is fed to molex unit The sulfur and nitrogen levels are reduced to 1 ppm or less
PARAMETERS DESIGN ACTUALPlant load() 100 115Hydrobon feed rate(mthr) 58 60Temperature 416 310Pressure (kgcm2 g) 822 62H2HC ratio 385 460Recycle hydrogen purity(mole)
75 min 95
Hydrobon feed specificationa Bromine
index(mg100gm)800 800
38 of 72
b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
39 of 72
HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
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4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
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FLOW DIAGRAM OF HYDROBON SECTION
42 of 72
Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
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nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
44 of 72
Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
45 of 72
DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
47 of 72
ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
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Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
49 of 72
Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
50 of 72
Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
51 of 72
=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
52 of 72
Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
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Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
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Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
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Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
STRIPPER
RERUN
Heart cut Kerosene (C10 to C14)
Light Kerosene
Feed kerosene
Heavy kerosene
b) HYDROBON
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit The catalyst used in Hydrobon reactor is S12 (Nickel ndashmolybdenumumoxide on alumina)
The heartcut kerosene from Prefractionation rerun column overhead is fed to this Hydrobon unit to remove sulfur nitrogen below 1 ppm This reaction is called as hydrotreating In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor
10 of 72
C-C-C-C-SH + H2 C-C-C-C + H2SOrganic sulfur(Mercaptan)
+ H2 C-C-C-C-C + NH3 N Nitrogen compound (Pyridine)
The reaction temperature is maintained at 310DegC while pressure is maintained at 65kgcm2g
The reactor temperature is maintained by charge heater where heat input is given by firing fuel
oil A recycle gas compressor and makeup gas compressor maintains the reactor pressure to 65
kgcm2g The H2 required for reaction is compressed in makeup gas compressor upto reactor
pressure
At reaction temperature cracking also takes place where some lighter (ltC10) are formed To
separate this the reactor effluent is passed to distillation column called Product Stripper The off
gases separated in stripper are burnt in heater as fuel
The H2S and NH3 formed in reaction form the ammonium sulfide salts The water is injected in
reactor effluent to prevent the deposition of salts that can corrode and foul the coolers The
desolved salts in water are further treated in sour water stripper to separate H2S and NH3 which
are burnt in heater as off gas
11 of 72
ProductSeparator
PRODUCT
STR
Lighters andOff gases
H2 from makeup gas compressor
Hydrobon reactor
To Molex unit
Charge heater
Feed from Prefractionation
Block Diagram of Hydrobon unit
c) MOLEX Molex process is effective method of separating normal paraffin from stream of hydrocarbon having normal and non-normal by physical selective adsorption process
The process uses solid adsorbent (Molecular sieve) where normal paraffin of straight chains are adsorbed in selective pores and non normal of branched chain are adsorbed in non selective pores
The adsorbed normal paraffin are then desorbed by normal pentane while non normal are desorbed by iso-octane
12 of 72
CHAMBER
CHAMBER
ROTARY VALVE
EXTRACT
RAFFINATE
Normal paraffin Non Normal
There are two adsorption chambers with 24 beds The process simulates countercurrent contact between fixed bed adsorbent and feed stream This simulation is done by flow directing device called ldquoRotary valverdquo
The separated streams from Molex chambers containing normal paraffin (Extract) and non normal (Raffinate) are fed to two distillation columns a) Extract column and b) Raffinate column In both distillation columns desorbent is separated from top and sidecut and recycled for desorption While bottom product of Extract column is Normal paraffin send to storage
E R
F
D
13 of 72
STRIPPER
RERUN
Heart cut Paraffin (C10 to C13)
Light NP
Feed NP
Heavy NP
2) Back EndAs described earlier Linear alkyl benzene (LAB) is produced from linear olefins by UOP detergent alkylation process The raw material normal paraffin of C10 to C14 from front end is processed in back end in series of processes they are
a) Prefractionation b) Pacol c) Alkylation
a) PREFRACTIONATION The normal paraffin of C10 to C14 carbon range is separated to Normal paraffin of C10 to C13 carbon range in two distillation columns in series
1) Stripper column In this distillation column lighter compound (if any) and partly C10 paraffin is removed as light normal paraffin (LNP) from top This LNP is sold in market as byproduct The bottoms is send to Rerun column
2) Rerun ColumnIn this column heartcut paraffin (C10 to C13) is separated from top as distillate The bottoms containing mainly C14 paraffin is sold in market as heavy normal paraffin (HNP) as byproduct
14 of 72
b) PACOL (Paraffin converted to olefin)
The normal paraffin of carbon range C10 to C13 is converted to linear olefins of carbon range C10 to C13 by Dehydrogenation reaction in UOP Pacol process
The catalyst used in reactor is alumina based platinum catalyst
Platinum catalyst
CH3-C-C-C-CH3 CH3 - C = C ndash C ndash CH3 + H2
N paraffin Linear Mono olefins
There are some side reactions takes places in Pacol they are
CH3 - C = C ndash C ndash CH3 CH3 - C = C = C ndash CH3 + H2
Linear Mono olefins Linear Di olefins
CH3 - C = C = C ndash CH3 Aromatics + H2
Linear Di olefins
As it is dehydrogenation reaction H2 gas is separated from reactor effluent in contact condenser and send to Front End for Hydrobon makeup gas compressor
Cracking also takes place in reactor where ltC10 paraffin and olefins are formed which is removed in distillation column called Pacol stripper The gas separated in stripper is burnt in heater as off gases
The reaction temperature is 470 to 495 DegC while pressure is kept low at 13 kgcm2g
The life of pacol catalyst is about 30 to 40 days As life of the catalyst is low there are two pacol reactors for continuous running of the plant
The conversion of paraffin is about 12 to 13
15 of 72
ContactCondenser
PACOL
STPR
Lighters andOff gases
Pacol reactor
To Alkylation
Charge heater
Normal ParaffinFeed
H2 to front end
DEFINE UNIT
The main purpose of this unit is to increase overall yield of LAB The Diolefins formed in Pacol reaction is converted to Mono olefins and normal paraffin thereby generating more LAB and lesser byproducts
The catalyst used in this reactor is Nickel based on alumina
Nickel catalyst
Diolefins + H2 Mono olefins
Diolefins + H2 Normal Paraffin
The reaction temperature is 180 DegC and pressure is 140 Kgcm2g
Block Diagram of Pacol Unit
16 of 72
IMIXER
2MIXER
HFSTRIPPER
C) ALKYLATION
As described earlier linear olefins (C10 to C13) are alkylated in this unit to form Linear alkyl Benzene (LAB) in presence of HF acid catalyst
The mono olefins are conveterd to Linear alkyl benzene (LAB) while diolefins are conveterd to Heavy alkyl Benzene (HAB) The aromatics are extracted in counter current extraction of HF acid and are separated in distillation column called Acid regenerators
HF acid catalyst
R- CH = CH ndashCH2 ndash Rrsquo + Benzene R-CH-CH2-CH2-Rrsquo
M Olefins
Where R and Rrsquo are alkyl groups (CH3) LAB
R-CH=CH-CH=CH-Rrsquo + 2 Benzene Heavy alkyl benzene
Di olefins HAB
The reaction is instantaneous and carried through a two stage mixer settler system The reactor section effluent is then processed in series of distillation columns where excess Benzene Paraffin LAB and byproduct Heavy alkyl benzene (HAB) gets separated
The separated benzene is recycled back to HF alkylation reactor while separated Paraffin is recycled to Pacol reactor for reaction The product Linear alkyl benzene (LAB) and byproduct Heavy alkyl benzene (HAB) are send to storage
The aromatics and non-normal which are formed in Pacol reaction are extracted in HF reaction unit by counter current extraction of HF acid as POLYMER This polymer is separated in Acid regenerators and then neutralized with KOH and send to storage
Block Diagram of Alkylation process
17 of 72
PROCESS INPUTS amp OUTPUTS
18 of 72
As described earlier plant is divided into two sections
a) Front End for Normal paraffin production from Keroseneb) Back End for Linear alkyl Benzene (LAB) production from N paraffin
The raw material kerosene is supplied to the plant from two sources
a) From Bharat Petroleum Corp Ltd Chembur (BPCL) via 55 Km pipelineb) From Reliance Petroleum Ltd Jamnagar via Shipping
The light kerosene heavy kerosene and Raffinate from front end are combined and send as return kerosene via pipeline or shipping to either BPCL or to RPL Jamnagar
The manufacturing of LAB is done in two grades
a) Domestic grade (Molecular weight 235 to 239)b) Export grade (Molecular weight 239 to 240)
The byproducts of LAB plant are
a) Light Normal paraffinb) Heavy normal paraffinc) Heavy alkyl Benzened) Tar polymer
Installed Capacities
A) For Normal Paraffin 115000 MT Highest prod 126596 MT in year 2001-2002
B) For LAB 100000 MT Highest prod 112484 MT in year 1999-2000
Plant load
A) For Normal Paraffin 117
B) For LAB 120 Production per day
A) For Normal Paraffin 330 MT day (Avrg)
B) For LAB 324 MTday (Avrg)
Customers
19 of 72
1) The Normal paraffin produced in LAB plant is normally used for captive consumption for producing LAB
2) The main customer of LAB is Ms Hindustan Lever and Procter amp Gamble Ltd and their subsidiary
3) The LAB is exported to Europe American African and Asian countries4) The light and Heavy normal paraffin is used to manufacture Chlorinated Paraffin Wax5) Heavy alkyl Benzene is used as lubricants in oil industry
Utility system in LAB plant
Hot oil system
There are two Hot oil Heaters available in LAB plant one for Front End and other is for Back End The Heaters are fired with furnace oil LSHS and off gases from process
The Hot oil (Dow Therm) which is thermic fluid is heated in these Hot oil heaters
The all heat inputs to the column preheater are given by circulating Hot oil at supply temperature of 330 DegC
Effluent System
The effluent generated in LAB plant mainly constitute
a) Fluoride Maximum limit lt 10 ppmb) Oil Maximum limit lt 10 ppm
For reduction of fluoride in effluent water LAB plant have two neutralisation basins where effluent from HF area is collected and then reacted with Lime (CaCO3) to reduce fluoride content below 10ppm
For reduction of oil in effluent water LAB plant have CPI separator installed to separate oil from effluent water The oil separated is send to Slope oil storage
In addition to this there is hydrocarbon pit installed in front end to collect pump and filter drains which is being blended in return kerosene to reduce oil load in effluent systemThere all oil collection pits installed in storm water channels to avoid oil going into the river via gates
20 of 72
Cooling water systemFor cooling the final products Byproducts to normal ambient temperatures the products byproducts are cooled in coolers The cooling media used is water There are three cooling towers installed in LAB planta) HF cooling tower it is separate cooling tower to avoid HF ingrace in coolers in non-HF
areab) Front End Cooling towerc) Back End cooling tower
Fin Fan coolers The distillation columns overheads are condensed in air-cooled fin fan coolers The advantage of these coolers over water-cooled coolers is low operating cost
Safety measures taken in LAB Plant
1) Safety Interlocks for tripping the operation of equipments in case process variables touches maximum allowable value
2) Flare system for burning excess gases from process3) Infra red detection system for Pacol Reactor and Hot pumps 4) Hydrocarbon detection system for detecting hydrocarbon leakages5) H2S detection system and siren for detecting H2S gas leakages 6) HF Detection system for detecting HF leakages7) Schedule HF leak testing of HF flanges8) Application of HF detection paints to all HF flanges to detect HF leak by decolouration9) Schedule Thickness survey of pipelines in HF area 10) Fire water sprinkler system for HF vessels Columns and pumps11) Fire water sprinkler system for Hot oil pumps12) Yellow boundary marking of HF area where personal protective equipments (PPErsquos) are
mandatory 13) Personal protective equipments (PPErsquos) for HF area Different types of PVC suits are defined
for different types of jobs ( A B C and D type)14) Separate breathing air reciprocating compressor for breathing air for C and D type PVC
suits in case of eemergency15) KOH scrubbing for venting from all HF equipments so that HF will not release into the
flare16) Daily Benzene monitoring with dragger tubes to detect any Benzene leaks from process17) Close draining system of HF and Benzene
21 of 72
PROJECT ndashI
The project is about developing a ldquoBENZENE-WATER WASHrdquo system to remove the impurities coming with fresh benzene that enters into benzene stripper and effects thefin-fan cooler The project is about developing such a scheme which will remove these impurities before entering the benzene stripper to eliminate the failure of fin-fan cooler
The scheme should also be such that it should not reduce the efficiency of the equipment and should be cost-effective
What is Benzene stripper
The high volatility of water dissolved in hydrocarbons is used in this column to obtain water-free benzene in the column bottoms which also removes any dissolved oxygen or non-condensibles in the benzene or off spec feeds Makeup benzene is fed to the overhead receiver on level control reset by the overhead receiver level controller It is refluxed via the overhead pump on flow control reset by the column bottom level controller and sent to the reaction section by the bottoms pump via the benzene stripper feedbottoms exchanger on flow control which is reset by the benzene column receiver level controller The benzene stripper receiver floats on the flare and is sized big enough to allow enough settling time for the water There is a small nitrogen flow via a conservation vent into the receiver vapor flare to maintain a slight nitrogen purge Water is collected in the boot and drained periodically whenever there is a boot high alarm Maintain a visible benzene water interface in the boot sight glass The benzene at the column bottom normally has a water content of less than 20ppm actually much lower if the column is operated well A moisture analyzer alarm high is provided The heat input to the column is provided by a hot oil reboiler with the hot oil flow controlled Off-spec material from the off-spec tank is normally rerun via the benzene stripper coming into the column receiver
What is the Issue
The benzene stripper column overheads are condensed in air-cooler (fin-fan coolers EC-301)The advantage of using this fin-fan cooler is the low operating cost no space constraint as are not on ground level etc This tube-bundle was failing at a frequency of once in a span of two years Failure analysis study was carried out and found that there are some impurities coming along with fresh benzene which are forming acidic solution after condensing in fin-fan This acidic solution formed was causing the repeated failure of tube-bundle
Water dosing was started upstream of the fin-fan bundle to dissolve out the impurities or to neutralize the acidic solution so that tubes can be saved This practice was started in 2008 Even after this modification the failures and continue and its difficult to analyze that what type of impurities are coming with benzene
22 of 72
So to eliminate this problem a scheme has been plotted to design a benzene scrubbing system This will be basically washing of benzene with DM water to remove the impurities before it enters the benzene stripper
The schematic diagram of this system is shown below
The scheme consists of a static mixture for mixing benzene and water for a particular residence time and at a particular velocity as required A gravity settler is for separating benzene and water on the basis of density difference
23 of 72
STATIC MIXER
This mixing device has no moving parts is simple and its cost can be quite reasonable when compared to mechanical driven mixers Static or motionless mixers are relatively new development and have proven to be effective for many specific and valuable process application It is useful for a wide range of viscosity fluids particularly useful in liquid-liquid mixing and also for some gas-liquid dispersion
The concept of motionless mixers is to achieve a uniform composition and temperature distribution in fluids flowing through the device The concept is build around a stationary rigid element placed in a pipe or cylinder that uses the energy of fluid flowing past to produce the mixing The unit becomes more efficient by adding additional static elements causing the flowing fluid elements to split rearrange recombine and split again to repeat the process lsquoxrsquo times for a uniform or homogeneous flowing stream is produced at discharge
Principle of operation
The static mixer unit is a series of fixed helical elements enclosed within a tubular housing
LIQUID ndash LIQUID SEPARATION(Decanters)
Separation of two liquid phases immiscible or partially miscible liquids is a common requirement in the process industries It is also frequently necessary to separate small quantities of entrained water from process streams The simplest form of equipment used to separate liquid phases is the gravity settling tank the decanter Various proprietary equipment is also used to promote coalescence and improve separation in difficult systems or where emulsions are likely to form Centrifugal separators are also used
Decanters (settlers)
Decanters are used to separate liquids where there is a sufficient difference in density between the liquids for the droplets to settle readily Decanters are essentially tanks which give sufficient residence time for the droplets of the dispersed phase to rise (or settle ) to the interface between the phases and coalesce
In an operating decanter there will be three distinct zones or bands clear heavy liquid separating dispersed liquid (the dispersion zone) and clear light liquid The position of the interface can be controlled with or without the use of instruments by use of a siphon take-off for the heavy liquid
24 of 72
Vertical decanter
The height of the take-off can be determined by making a pressure balance Neglecting friction loss in the pipes the pressure exerted by the combined height of the heavy and light liquid in the vessel must be balanced by the height of the heavy liquid in the take-off leg
(z1-z3)Ρ1g + z3 Ρ2g= z2 Ρ2g
z2 = (z1-z3) Ρ1 + z3 (1)Ρ2
WhereZ1= height from datum to light liquid overflow m Z2=height from datum to heavy liquid overflow m Z3=height from datum to interface m Ρ1=density of the light liquid kgmsup3 Ρ2=density of the heavy liquid kg msup3
The height of the liquid interface should be measured accurately when the liquid densities are close when one component is present only in small quantities or when the throughput is very small A typical scheme for the automatic control of the interface using a level instrument that can detect the position of the interface is shown in the diagram below Where one phase is present only in small amounts it is often recycled to the decanter feed to give more stable operation
25 of 72
CALCULATIONS
STATIC MIXER DESIGN
Required data
1 Physical properties of materials Density kgmsup3
Viscosity Pas = 0001Cp
2 Pressure drop Pressure drop in static mixer is best described by comparison with pipe flow
3 Geometrical parameters Diameter m
Type of static mixer constant (k)
Length (l) m
4 Process variables
Flow rate msup3s TemperaturedegC Pressure bar
26 of 72
Pressure drop calculation
a) Velocity (v)
V = Qπ4 Dsup2
b) Reynoldsrsquos number(Re)
Re= dvρμ
c) Pressure drop (Δp)For Re lt50 Δp =k1x μ x l xQd dsup3
k1= laminar flow constant
For Re gt10sup3 Δp =k2 x ρ x l x vsup2d 2
= k2 x Q x l x 8 x Qsup2d prodsup2 d⁴
k2= turbulent flow constant
Pipe diameter Flow seems to be turbulent as both the materials (B2+ H2O) are not viscous
D =39Q ⁰ ⁴⁵ ρ sup1sup3⁰
Q =52 + 572 = 1092msup3hr = 303 x 10macrsup3msup3s= 38564 ftsup3hr
Ρ = 926328 kgmsup3 =57828 lbftsup3
D =39 x Q ⁰ ⁴⁵ x ρ sup1sup3⁰
D =39 x (38564) ⁰ ⁴⁵ x (57828) sup1sup3⁰ 3600
D= 24 inch = 25 inch = 00635m
27 of 72
Velocity(v)
V =4 Q proddsup2
= 303 x 10macrsup3 msup3s x 4 314 x (00635)sup2
= 0957 ms (approx 1ms)
Reynoldrsquosnumber(Re)
Re = dvρ Μ = 00635 x 1 x 926328 0572
Re =103 x 10⁵
Thus the flow is highly turbulent
Flow regime Reynoldrsquos no(Re)
No of element No of elements to add if viscosity ratio between fluids exceeds 10001
No of elements to add if volumetric ratio between fluids exceeds 1001
Laminar lt1 24 6 61-10 18 6 611-50 14 6 651-100 12 6 6101-500 10 6 6
Transitional 501-1000 8 4 41001-2000 6 4 4
Turbulent 2001-5000 4 2 25001+ 2 2 2
Thus from the above table the mixer will have 2 elements
The mixer length will be based on the number of elements required An approximate length can be determined by multiplying the number of elements by 15
Mixer length = 15 x 2 =3
28 of 72
For turbulent flow applications it is generally recommended that a minimum velocity of 10 ftsec be maintained
V= 0408 x QDsup2 = 0408 x 4813sup2 = 218 ftsec =066 ms
DECANTER DESIGN
Benzene Water
Flow rate (msup3h) 52 572
Flow rate (kgh) 4543812 570311
Density (kgmsup3) 87381 99704
Viscosity (Pas) 0000604 000089
Take Dd = 150microm
microd = (150 Х 10ˉ⁶)sup2 Х 981 Х (87381-99704) 18 Х 000089
microd = -169787 Х 10ˉsup3 ms = -17 mms (rising)
As the flow rate is small we will use a vertical cylindrical vessel
The decanter vessel is sized on the basis that the velocity of the continuous phase must be less than settling velocity of the droplets of the dispersed phase Plug flow is assumed and the velocity of the continuous phase calculated using the area of the interfacemicroc =Lclt microdAiWhere microd = settling velocity of the dispersed phase droplets msmicroc = velocity of the continuous phase msLc = continuous phase volumetric flow rate msup3sAi = area of the interface msup2
29 of 72
Lc = 570311 X 1 99704 3600
= 00015889 msup3s
Ai=Lc = 00015889 microc 00017
= 0935817588 msup2
For a vertical cylindrical decanterAi = prodrsup2
r = 0935817588 prodr = 0545835318 m
Diameter= 1091670637 m
Taking the height as twice the diameter a reasonable value for a cylinder
Height = 2183341274 m
The position of the interface should be such that the band of droplets that collect at the interface waiting to coalesce and cross the interface does not extend to the bottom (or top) of the vessel The depth of the dispersion band is a function of the liquid flow rate and the interfacial area A value of to per cent of the decanter height is usually taken for the design purposes
Take the dispersion band as 10 per cent of the height = 021833mThe residence time of the droplets in the dispersion band = 021833 = 021833microd 00017 =1285926 s (approx 2 min)
This is satisfactory time a time of 2 to 5 min is normally recommended Thus the size of the water (continuous heavy phase) droplets that could be entrained with benzene (light phase) will be
Velocity of benzene phase = 4543812 X 1 X 1 873811 3600093581
=0001543511 ms =1543511mms
30 of 72
So from equation ( ) So the entrained droplet size will be =00015435 X 18 X 0000604 frac12 981 X (99704-873812)
=00001178 m=1178 microm
which is satisfactory below 150 microm
Piping arrangement
To minimize entrainment by the jet of liquid entering the vessel the inlet velocity for a decanter should keep below 1 ms
The velocity from static mixer= 066 ms
Flow rate= 4543812 + 570311 X 1 87381 99704 3600
= 0003033345msup3s
Area of pipe= flow ratevelocity
= 0003033345066
= 0004554572msup2
Pipe diameter =0004554572 x 4prod
= 0076158749 m =29983 inch (approx 3 in)
31 of 72
32 of 72
33 of 72
34 of 72
35 of 72
36 of 72
37 of 72
PROJECT II
CALULATING THE DEW POINT
This project is about the study and evaluation of the performance of the compressors in the Hydrobon section of the LAB plant which is installed to optimize the purity of hydrogen coming from the product separators The compressors in this section include recycle gas compressor and make-up gas compressorThe purity of hydrogen can be increased upto 90
This project will give the company an overall view of this loop The plant is running well about its installed capacity(131-140) The company wants to retain the purity level of nearly 90 for hydrogen even after operating above installed capacity Hence the current project will give the company an idea of the current hydrogen quality(purity) which is obtained and give an idea about changes if any to be made to existing process set-up
HYDROBON REACTOR
Hydrobon reactor is designed to remove contaminants present in the raw kerosene without changing the boiling range The hydrocarbon is passed through a 2 bed reactor feed with S 12 catalyst through a feed effluent exchanger and charge heater which maintain the required reaction temperature(310 c) The reaction required hydrogen gas which is supplied from pacol net gas generated from back end and tattoray hydrogen from PX plantThe reaction charge is heated to the reaction temperature in the charge heater enters the reactor from the top and is distributed over the catalyst bed Catalytic hydrogenation takes place in the reactor The impurities react with hydrogen and form salts which are subsequently separated and finally removed in sour water stripper The reactor effluents after separation is fed to the product stripper to remove lighters and hydrotreated kerosene is fed to molex unit The sulfur and nitrogen levels are reduced to 1 ppm or less
PARAMETERS DESIGN ACTUALPlant load() 100 115Hydrobon feed rate(mthr) 58 60Temperature 416 310Pressure (kgcm2 g) 822 62H2HC ratio 385 460Recycle hydrogen purity(mole)
75 min 95
Hydrobon feed specificationa Bromine
index(mg100gm)800 800
38 of 72
b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
39 of 72
HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
40 of 72
4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
41 of 72
FLOW DIAGRAM OF HYDROBON SECTION
42 of 72
Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
43 of 72
nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
44 of 72
Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
45 of 72
DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
46 of 72
DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
47 of 72
ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
48 of 72
Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
49 of 72
Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
50 of 72
Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
51 of 72
=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
52 of 72
Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
53 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
54 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
55 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
C-C-C-C-SH + H2 C-C-C-C + H2SOrganic sulfur(Mercaptan)
+ H2 C-C-C-C-C + NH3 N Nitrogen compound (Pyridine)
The reaction temperature is maintained at 310DegC while pressure is maintained at 65kgcm2g
The reactor temperature is maintained by charge heater where heat input is given by firing fuel
oil A recycle gas compressor and makeup gas compressor maintains the reactor pressure to 65
kgcm2g The H2 required for reaction is compressed in makeup gas compressor upto reactor
pressure
At reaction temperature cracking also takes place where some lighter (ltC10) are formed To
separate this the reactor effluent is passed to distillation column called Product Stripper The off
gases separated in stripper are burnt in heater as fuel
The H2S and NH3 formed in reaction form the ammonium sulfide salts The water is injected in
reactor effluent to prevent the deposition of salts that can corrode and foul the coolers The
desolved salts in water are further treated in sour water stripper to separate H2S and NH3 which
are burnt in heater as off gas
11 of 72
ProductSeparator
PRODUCT
STR
Lighters andOff gases
H2 from makeup gas compressor
Hydrobon reactor
To Molex unit
Charge heater
Feed from Prefractionation
Block Diagram of Hydrobon unit
c) MOLEX Molex process is effective method of separating normal paraffin from stream of hydrocarbon having normal and non-normal by physical selective adsorption process
The process uses solid adsorbent (Molecular sieve) where normal paraffin of straight chains are adsorbed in selective pores and non normal of branched chain are adsorbed in non selective pores
The adsorbed normal paraffin are then desorbed by normal pentane while non normal are desorbed by iso-octane
12 of 72
CHAMBER
CHAMBER
ROTARY VALVE
EXTRACT
RAFFINATE
Normal paraffin Non Normal
There are two adsorption chambers with 24 beds The process simulates countercurrent contact between fixed bed adsorbent and feed stream This simulation is done by flow directing device called ldquoRotary valverdquo
The separated streams from Molex chambers containing normal paraffin (Extract) and non normal (Raffinate) are fed to two distillation columns a) Extract column and b) Raffinate column In both distillation columns desorbent is separated from top and sidecut and recycled for desorption While bottom product of Extract column is Normal paraffin send to storage
E R
F
D
13 of 72
STRIPPER
RERUN
Heart cut Paraffin (C10 to C13)
Light NP
Feed NP
Heavy NP
2) Back EndAs described earlier Linear alkyl benzene (LAB) is produced from linear olefins by UOP detergent alkylation process The raw material normal paraffin of C10 to C14 from front end is processed in back end in series of processes they are
a) Prefractionation b) Pacol c) Alkylation
a) PREFRACTIONATION The normal paraffin of C10 to C14 carbon range is separated to Normal paraffin of C10 to C13 carbon range in two distillation columns in series
1) Stripper column In this distillation column lighter compound (if any) and partly C10 paraffin is removed as light normal paraffin (LNP) from top This LNP is sold in market as byproduct The bottoms is send to Rerun column
2) Rerun ColumnIn this column heartcut paraffin (C10 to C13) is separated from top as distillate The bottoms containing mainly C14 paraffin is sold in market as heavy normal paraffin (HNP) as byproduct
14 of 72
b) PACOL (Paraffin converted to olefin)
The normal paraffin of carbon range C10 to C13 is converted to linear olefins of carbon range C10 to C13 by Dehydrogenation reaction in UOP Pacol process
The catalyst used in reactor is alumina based platinum catalyst
Platinum catalyst
CH3-C-C-C-CH3 CH3 - C = C ndash C ndash CH3 + H2
N paraffin Linear Mono olefins
There are some side reactions takes places in Pacol they are
CH3 - C = C ndash C ndash CH3 CH3 - C = C = C ndash CH3 + H2
Linear Mono olefins Linear Di olefins
CH3 - C = C = C ndash CH3 Aromatics + H2
Linear Di olefins
As it is dehydrogenation reaction H2 gas is separated from reactor effluent in contact condenser and send to Front End for Hydrobon makeup gas compressor
Cracking also takes place in reactor where ltC10 paraffin and olefins are formed which is removed in distillation column called Pacol stripper The gas separated in stripper is burnt in heater as off gases
The reaction temperature is 470 to 495 DegC while pressure is kept low at 13 kgcm2g
The life of pacol catalyst is about 30 to 40 days As life of the catalyst is low there are two pacol reactors for continuous running of the plant
The conversion of paraffin is about 12 to 13
15 of 72
ContactCondenser
PACOL
STPR
Lighters andOff gases
Pacol reactor
To Alkylation
Charge heater
Normal ParaffinFeed
H2 to front end
DEFINE UNIT
The main purpose of this unit is to increase overall yield of LAB The Diolefins formed in Pacol reaction is converted to Mono olefins and normal paraffin thereby generating more LAB and lesser byproducts
The catalyst used in this reactor is Nickel based on alumina
Nickel catalyst
Diolefins + H2 Mono olefins
Diolefins + H2 Normal Paraffin
The reaction temperature is 180 DegC and pressure is 140 Kgcm2g
Block Diagram of Pacol Unit
16 of 72
IMIXER
2MIXER
HFSTRIPPER
C) ALKYLATION
As described earlier linear olefins (C10 to C13) are alkylated in this unit to form Linear alkyl Benzene (LAB) in presence of HF acid catalyst
The mono olefins are conveterd to Linear alkyl benzene (LAB) while diolefins are conveterd to Heavy alkyl Benzene (HAB) The aromatics are extracted in counter current extraction of HF acid and are separated in distillation column called Acid regenerators
HF acid catalyst
R- CH = CH ndashCH2 ndash Rrsquo + Benzene R-CH-CH2-CH2-Rrsquo
M Olefins
Where R and Rrsquo are alkyl groups (CH3) LAB
R-CH=CH-CH=CH-Rrsquo + 2 Benzene Heavy alkyl benzene
Di olefins HAB
The reaction is instantaneous and carried through a two stage mixer settler system The reactor section effluent is then processed in series of distillation columns where excess Benzene Paraffin LAB and byproduct Heavy alkyl benzene (HAB) gets separated
The separated benzene is recycled back to HF alkylation reactor while separated Paraffin is recycled to Pacol reactor for reaction The product Linear alkyl benzene (LAB) and byproduct Heavy alkyl benzene (HAB) are send to storage
The aromatics and non-normal which are formed in Pacol reaction are extracted in HF reaction unit by counter current extraction of HF acid as POLYMER This polymer is separated in Acid regenerators and then neutralized with KOH and send to storage
Block Diagram of Alkylation process
17 of 72
PROCESS INPUTS amp OUTPUTS
18 of 72
As described earlier plant is divided into two sections
a) Front End for Normal paraffin production from Keroseneb) Back End for Linear alkyl Benzene (LAB) production from N paraffin
The raw material kerosene is supplied to the plant from two sources
a) From Bharat Petroleum Corp Ltd Chembur (BPCL) via 55 Km pipelineb) From Reliance Petroleum Ltd Jamnagar via Shipping
The light kerosene heavy kerosene and Raffinate from front end are combined and send as return kerosene via pipeline or shipping to either BPCL or to RPL Jamnagar
The manufacturing of LAB is done in two grades
a) Domestic grade (Molecular weight 235 to 239)b) Export grade (Molecular weight 239 to 240)
The byproducts of LAB plant are
a) Light Normal paraffinb) Heavy normal paraffinc) Heavy alkyl Benzened) Tar polymer
Installed Capacities
A) For Normal Paraffin 115000 MT Highest prod 126596 MT in year 2001-2002
B) For LAB 100000 MT Highest prod 112484 MT in year 1999-2000
Plant load
A) For Normal Paraffin 117
B) For LAB 120 Production per day
A) For Normal Paraffin 330 MT day (Avrg)
B) For LAB 324 MTday (Avrg)
Customers
19 of 72
1) The Normal paraffin produced in LAB plant is normally used for captive consumption for producing LAB
2) The main customer of LAB is Ms Hindustan Lever and Procter amp Gamble Ltd and their subsidiary
3) The LAB is exported to Europe American African and Asian countries4) The light and Heavy normal paraffin is used to manufacture Chlorinated Paraffin Wax5) Heavy alkyl Benzene is used as lubricants in oil industry
Utility system in LAB plant
Hot oil system
There are two Hot oil Heaters available in LAB plant one for Front End and other is for Back End The Heaters are fired with furnace oil LSHS and off gases from process
The Hot oil (Dow Therm) which is thermic fluid is heated in these Hot oil heaters
The all heat inputs to the column preheater are given by circulating Hot oil at supply temperature of 330 DegC
Effluent System
The effluent generated in LAB plant mainly constitute
a) Fluoride Maximum limit lt 10 ppmb) Oil Maximum limit lt 10 ppm
For reduction of fluoride in effluent water LAB plant have two neutralisation basins where effluent from HF area is collected and then reacted with Lime (CaCO3) to reduce fluoride content below 10ppm
For reduction of oil in effluent water LAB plant have CPI separator installed to separate oil from effluent water The oil separated is send to Slope oil storage
In addition to this there is hydrocarbon pit installed in front end to collect pump and filter drains which is being blended in return kerosene to reduce oil load in effluent systemThere all oil collection pits installed in storm water channels to avoid oil going into the river via gates
20 of 72
Cooling water systemFor cooling the final products Byproducts to normal ambient temperatures the products byproducts are cooled in coolers The cooling media used is water There are three cooling towers installed in LAB planta) HF cooling tower it is separate cooling tower to avoid HF ingrace in coolers in non-HF
areab) Front End Cooling towerc) Back End cooling tower
Fin Fan coolers The distillation columns overheads are condensed in air-cooled fin fan coolers The advantage of these coolers over water-cooled coolers is low operating cost
Safety measures taken in LAB Plant
1) Safety Interlocks for tripping the operation of equipments in case process variables touches maximum allowable value
2) Flare system for burning excess gases from process3) Infra red detection system for Pacol Reactor and Hot pumps 4) Hydrocarbon detection system for detecting hydrocarbon leakages5) H2S detection system and siren for detecting H2S gas leakages 6) HF Detection system for detecting HF leakages7) Schedule HF leak testing of HF flanges8) Application of HF detection paints to all HF flanges to detect HF leak by decolouration9) Schedule Thickness survey of pipelines in HF area 10) Fire water sprinkler system for HF vessels Columns and pumps11) Fire water sprinkler system for Hot oil pumps12) Yellow boundary marking of HF area where personal protective equipments (PPErsquos) are
mandatory 13) Personal protective equipments (PPErsquos) for HF area Different types of PVC suits are defined
for different types of jobs ( A B C and D type)14) Separate breathing air reciprocating compressor for breathing air for C and D type PVC
suits in case of eemergency15) KOH scrubbing for venting from all HF equipments so that HF will not release into the
flare16) Daily Benzene monitoring with dragger tubes to detect any Benzene leaks from process17) Close draining system of HF and Benzene
21 of 72
PROJECT ndashI
The project is about developing a ldquoBENZENE-WATER WASHrdquo system to remove the impurities coming with fresh benzene that enters into benzene stripper and effects thefin-fan cooler The project is about developing such a scheme which will remove these impurities before entering the benzene stripper to eliminate the failure of fin-fan cooler
The scheme should also be such that it should not reduce the efficiency of the equipment and should be cost-effective
What is Benzene stripper
The high volatility of water dissolved in hydrocarbons is used in this column to obtain water-free benzene in the column bottoms which also removes any dissolved oxygen or non-condensibles in the benzene or off spec feeds Makeup benzene is fed to the overhead receiver on level control reset by the overhead receiver level controller It is refluxed via the overhead pump on flow control reset by the column bottom level controller and sent to the reaction section by the bottoms pump via the benzene stripper feedbottoms exchanger on flow control which is reset by the benzene column receiver level controller The benzene stripper receiver floats on the flare and is sized big enough to allow enough settling time for the water There is a small nitrogen flow via a conservation vent into the receiver vapor flare to maintain a slight nitrogen purge Water is collected in the boot and drained periodically whenever there is a boot high alarm Maintain a visible benzene water interface in the boot sight glass The benzene at the column bottom normally has a water content of less than 20ppm actually much lower if the column is operated well A moisture analyzer alarm high is provided The heat input to the column is provided by a hot oil reboiler with the hot oil flow controlled Off-spec material from the off-spec tank is normally rerun via the benzene stripper coming into the column receiver
What is the Issue
The benzene stripper column overheads are condensed in air-cooler (fin-fan coolers EC-301)The advantage of using this fin-fan cooler is the low operating cost no space constraint as are not on ground level etc This tube-bundle was failing at a frequency of once in a span of two years Failure analysis study was carried out and found that there are some impurities coming along with fresh benzene which are forming acidic solution after condensing in fin-fan This acidic solution formed was causing the repeated failure of tube-bundle
Water dosing was started upstream of the fin-fan bundle to dissolve out the impurities or to neutralize the acidic solution so that tubes can be saved This practice was started in 2008 Even after this modification the failures and continue and its difficult to analyze that what type of impurities are coming with benzene
22 of 72
So to eliminate this problem a scheme has been plotted to design a benzene scrubbing system This will be basically washing of benzene with DM water to remove the impurities before it enters the benzene stripper
The schematic diagram of this system is shown below
The scheme consists of a static mixture for mixing benzene and water for a particular residence time and at a particular velocity as required A gravity settler is for separating benzene and water on the basis of density difference
23 of 72
STATIC MIXER
This mixing device has no moving parts is simple and its cost can be quite reasonable when compared to mechanical driven mixers Static or motionless mixers are relatively new development and have proven to be effective for many specific and valuable process application It is useful for a wide range of viscosity fluids particularly useful in liquid-liquid mixing and also for some gas-liquid dispersion
The concept of motionless mixers is to achieve a uniform composition and temperature distribution in fluids flowing through the device The concept is build around a stationary rigid element placed in a pipe or cylinder that uses the energy of fluid flowing past to produce the mixing The unit becomes more efficient by adding additional static elements causing the flowing fluid elements to split rearrange recombine and split again to repeat the process lsquoxrsquo times for a uniform or homogeneous flowing stream is produced at discharge
Principle of operation
The static mixer unit is a series of fixed helical elements enclosed within a tubular housing
LIQUID ndash LIQUID SEPARATION(Decanters)
Separation of two liquid phases immiscible or partially miscible liquids is a common requirement in the process industries It is also frequently necessary to separate small quantities of entrained water from process streams The simplest form of equipment used to separate liquid phases is the gravity settling tank the decanter Various proprietary equipment is also used to promote coalescence and improve separation in difficult systems or where emulsions are likely to form Centrifugal separators are also used
Decanters (settlers)
Decanters are used to separate liquids where there is a sufficient difference in density between the liquids for the droplets to settle readily Decanters are essentially tanks which give sufficient residence time for the droplets of the dispersed phase to rise (or settle ) to the interface between the phases and coalesce
In an operating decanter there will be three distinct zones or bands clear heavy liquid separating dispersed liquid (the dispersion zone) and clear light liquid The position of the interface can be controlled with or without the use of instruments by use of a siphon take-off for the heavy liquid
24 of 72
Vertical decanter
The height of the take-off can be determined by making a pressure balance Neglecting friction loss in the pipes the pressure exerted by the combined height of the heavy and light liquid in the vessel must be balanced by the height of the heavy liquid in the take-off leg
(z1-z3)Ρ1g + z3 Ρ2g= z2 Ρ2g
z2 = (z1-z3) Ρ1 + z3 (1)Ρ2
WhereZ1= height from datum to light liquid overflow m Z2=height from datum to heavy liquid overflow m Z3=height from datum to interface m Ρ1=density of the light liquid kgmsup3 Ρ2=density of the heavy liquid kg msup3
The height of the liquid interface should be measured accurately when the liquid densities are close when one component is present only in small quantities or when the throughput is very small A typical scheme for the automatic control of the interface using a level instrument that can detect the position of the interface is shown in the diagram below Where one phase is present only in small amounts it is often recycled to the decanter feed to give more stable operation
25 of 72
CALCULATIONS
STATIC MIXER DESIGN
Required data
1 Physical properties of materials Density kgmsup3
Viscosity Pas = 0001Cp
2 Pressure drop Pressure drop in static mixer is best described by comparison with pipe flow
3 Geometrical parameters Diameter m
Type of static mixer constant (k)
Length (l) m
4 Process variables
Flow rate msup3s TemperaturedegC Pressure bar
26 of 72
Pressure drop calculation
a) Velocity (v)
V = Qπ4 Dsup2
b) Reynoldsrsquos number(Re)
Re= dvρμ
c) Pressure drop (Δp)For Re lt50 Δp =k1x μ x l xQd dsup3
k1= laminar flow constant
For Re gt10sup3 Δp =k2 x ρ x l x vsup2d 2
= k2 x Q x l x 8 x Qsup2d prodsup2 d⁴
k2= turbulent flow constant
Pipe diameter Flow seems to be turbulent as both the materials (B2+ H2O) are not viscous
D =39Q ⁰ ⁴⁵ ρ sup1sup3⁰
Q =52 + 572 = 1092msup3hr = 303 x 10macrsup3msup3s= 38564 ftsup3hr
Ρ = 926328 kgmsup3 =57828 lbftsup3
D =39 x Q ⁰ ⁴⁵ x ρ sup1sup3⁰
D =39 x (38564) ⁰ ⁴⁵ x (57828) sup1sup3⁰ 3600
D= 24 inch = 25 inch = 00635m
27 of 72
Velocity(v)
V =4 Q proddsup2
= 303 x 10macrsup3 msup3s x 4 314 x (00635)sup2
= 0957 ms (approx 1ms)
Reynoldrsquosnumber(Re)
Re = dvρ Μ = 00635 x 1 x 926328 0572
Re =103 x 10⁵
Thus the flow is highly turbulent
Flow regime Reynoldrsquos no(Re)
No of element No of elements to add if viscosity ratio between fluids exceeds 10001
No of elements to add if volumetric ratio between fluids exceeds 1001
Laminar lt1 24 6 61-10 18 6 611-50 14 6 651-100 12 6 6101-500 10 6 6
Transitional 501-1000 8 4 41001-2000 6 4 4
Turbulent 2001-5000 4 2 25001+ 2 2 2
Thus from the above table the mixer will have 2 elements
The mixer length will be based on the number of elements required An approximate length can be determined by multiplying the number of elements by 15
Mixer length = 15 x 2 =3
28 of 72
For turbulent flow applications it is generally recommended that a minimum velocity of 10 ftsec be maintained
V= 0408 x QDsup2 = 0408 x 4813sup2 = 218 ftsec =066 ms
DECANTER DESIGN
Benzene Water
Flow rate (msup3h) 52 572
Flow rate (kgh) 4543812 570311
Density (kgmsup3) 87381 99704
Viscosity (Pas) 0000604 000089
Take Dd = 150microm
microd = (150 Х 10ˉ⁶)sup2 Х 981 Х (87381-99704) 18 Х 000089
microd = -169787 Х 10ˉsup3 ms = -17 mms (rising)
As the flow rate is small we will use a vertical cylindrical vessel
The decanter vessel is sized on the basis that the velocity of the continuous phase must be less than settling velocity of the droplets of the dispersed phase Plug flow is assumed and the velocity of the continuous phase calculated using the area of the interfacemicroc =Lclt microdAiWhere microd = settling velocity of the dispersed phase droplets msmicroc = velocity of the continuous phase msLc = continuous phase volumetric flow rate msup3sAi = area of the interface msup2
29 of 72
Lc = 570311 X 1 99704 3600
= 00015889 msup3s
Ai=Lc = 00015889 microc 00017
= 0935817588 msup2
For a vertical cylindrical decanterAi = prodrsup2
r = 0935817588 prodr = 0545835318 m
Diameter= 1091670637 m
Taking the height as twice the diameter a reasonable value for a cylinder
Height = 2183341274 m
The position of the interface should be such that the band of droplets that collect at the interface waiting to coalesce and cross the interface does not extend to the bottom (or top) of the vessel The depth of the dispersion band is a function of the liquid flow rate and the interfacial area A value of to per cent of the decanter height is usually taken for the design purposes
Take the dispersion band as 10 per cent of the height = 021833mThe residence time of the droplets in the dispersion band = 021833 = 021833microd 00017 =1285926 s (approx 2 min)
This is satisfactory time a time of 2 to 5 min is normally recommended Thus the size of the water (continuous heavy phase) droplets that could be entrained with benzene (light phase) will be
Velocity of benzene phase = 4543812 X 1 X 1 873811 3600093581
=0001543511 ms =1543511mms
30 of 72
So from equation ( ) So the entrained droplet size will be =00015435 X 18 X 0000604 frac12 981 X (99704-873812)
=00001178 m=1178 microm
which is satisfactory below 150 microm
Piping arrangement
To minimize entrainment by the jet of liquid entering the vessel the inlet velocity for a decanter should keep below 1 ms
The velocity from static mixer= 066 ms
Flow rate= 4543812 + 570311 X 1 87381 99704 3600
= 0003033345msup3s
Area of pipe= flow ratevelocity
= 0003033345066
= 0004554572msup2
Pipe diameter =0004554572 x 4prod
= 0076158749 m =29983 inch (approx 3 in)
31 of 72
32 of 72
33 of 72
34 of 72
35 of 72
36 of 72
37 of 72
PROJECT II
CALULATING THE DEW POINT
This project is about the study and evaluation of the performance of the compressors in the Hydrobon section of the LAB plant which is installed to optimize the purity of hydrogen coming from the product separators The compressors in this section include recycle gas compressor and make-up gas compressorThe purity of hydrogen can be increased upto 90
This project will give the company an overall view of this loop The plant is running well about its installed capacity(131-140) The company wants to retain the purity level of nearly 90 for hydrogen even after operating above installed capacity Hence the current project will give the company an idea of the current hydrogen quality(purity) which is obtained and give an idea about changes if any to be made to existing process set-up
HYDROBON REACTOR
Hydrobon reactor is designed to remove contaminants present in the raw kerosene without changing the boiling range The hydrocarbon is passed through a 2 bed reactor feed with S 12 catalyst through a feed effluent exchanger and charge heater which maintain the required reaction temperature(310 c) The reaction required hydrogen gas which is supplied from pacol net gas generated from back end and tattoray hydrogen from PX plantThe reaction charge is heated to the reaction temperature in the charge heater enters the reactor from the top and is distributed over the catalyst bed Catalytic hydrogenation takes place in the reactor The impurities react with hydrogen and form salts which are subsequently separated and finally removed in sour water stripper The reactor effluents after separation is fed to the product stripper to remove lighters and hydrotreated kerosene is fed to molex unit The sulfur and nitrogen levels are reduced to 1 ppm or less
PARAMETERS DESIGN ACTUALPlant load() 100 115Hydrobon feed rate(mthr) 58 60Temperature 416 310Pressure (kgcm2 g) 822 62H2HC ratio 385 460Recycle hydrogen purity(mole)
75 min 95
Hydrobon feed specificationa Bromine
index(mg100gm)800 800
38 of 72
b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
39 of 72
HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
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4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
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FLOW DIAGRAM OF HYDROBON SECTION
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Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
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nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
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Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
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DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
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ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
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Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
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Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
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Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
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=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
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Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
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Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
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Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
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Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
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Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
ProductSeparator
PRODUCT
STR
Lighters andOff gases
H2 from makeup gas compressor
Hydrobon reactor
To Molex unit
Charge heater
Feed from Prefractionation
Block Diagram of Hydrobon unit
c) MOLEX Molex process is effective method of separating normal paraffin from stream of hydrocarbon having normal and non-normal by physical selective adsorption process
The process uses solid adsorbent (Molecular sieve) where normal paraffin of straight chains are adsorbed in selective pores and non normal of branched chain are adsorbed in non selective pores
The adsorbed normal paraffin are then desorbed by normal pentane while non normal are desorbed by iso-octane
12 of 72
CHAMBER
CHAMBER
ROTARY VALVE
EXTRACT
RAFFINATE
Normal paraffin Non Normal
There are two adsorption chambers with 24 beds The process simulates countercurrent contact between fixed bed adsorbent and feed stream This simulation is done by flow directing device called ldquoRotary valverdquo
The separated streams from Molex chambers containing normal paraffin (Extract) and non normal (Raffinate) are fed to two distillation columns a) Extract column and b) Raffinate column In both distillation columns desorbent is separated from top and sidecut and recycled for desorption While bottom product of Extract column is Normal paraffin send to storage
E R
F
D
13 of 72
STRIPPER
RERUN
Heart cut Paraffin (C10 to C13)
Light NP
Feed NP
Heavy NP
2) Back EndAs described earlier Linear alkyl benzene (LAB) is produced from linear olefins by UOP detergent alkylation process The raw material normal paraffin of C10 to C14 from front end is processed in back end in series of processes they are
a) Prefractionation b) Pacol c) Alkylation
a) PREFRACTIONATION The normal paraffin of C10 to C14 carbon range is separated to Normal paraffin of C10 to C13 carbon range in two distillation columns in series
1) Stripper column In this distillation column lighter compound (if any) and partly C10 paraffin is removed as light normal paraffin (LNP) from top This LNP is sold in market as byproduct The bottoms is send to Rerun column
2) Rerun ColumnIn this column heartcut paraffin (C10 to C13) is separated from top as distillate The bottoms containing mainly C14 paraffin is sold in market as heavy normal paraffin (HNP) as byproduct
14 of 72
b) PACOL (Paraffin converted to olefin)
The normal paraffin of carbon range C10 to C13 is converted to linear olefins of carbon range C10 to C13 by Dehydrogenation reaction in UOP Pacol process
The catalyst used in reactor is alumina based platinum catalyst
Platinum catalyst
CH3-C-C-C-CH3 CH3 - C = C ndash C ndash CH3 + H2
N paraffin Linear Mono olefins
There are some side reactions takes places in Pacol they are
CH3 - C = C ndash C ndash CH3 CH3 - C = C = C ndash CH3 + H2
Linear Mono olefins Linear Di olefins
CH3 - C = C = C ndash CH3 Aromatics + H2
Linear Di olefins
As it is dehydrogenation reaction H2 gas is separated from reactor effluent in contact condenser and send to Front End for Hydrobon makeup gas compressor
Cracking also takes place in reactor where ltC10 paraffin and olefins are formed which is removed in distillation column called Pacol stripper The gas separated in stripper is burnt in heater as off gases
The reaction temperature is 470 to 495 DegC while pressure is kept low at 13 kgcm2g
The life of pacol catalyst is about 30 to 40 days As life of the catalyst is low there are two pacol reactors for continuous running of the plant
The conversion of paraffin is about 12 to 13
15 of 72
ContactCondenser
PACOL
STPR
Lighters andOff gases
Pacol reactor
To Alkylation
Charge heater
Normal ParaffinFeed
H2 to front end
DEFINE UNIT
The main purpose of this unit is to increase overall yield of LAB The Diolefins formed in Pacol reaction is converted to Mono olefins and normal paraffin thereby generating more LAB and lesser byproducts
The catalyst used in this reactor is Nickel based on alumina
Nickel catalyst
Diolefins + H2 Mono olefins
Diolefins + H2 Normal Paraffin
The reaction temperature is 180 DegC and pressure is 140 Kgcm2g
Block Diagram of Pacol Unit
16 of 72
IMIXER
2MIXER
HFSTRIPPER
C) ALKYLATION
As described earlier linear olefins (C10 to C13) are alkylated in this unit to form Linear alkyl Benzene (LAB) in presence of HF acid catalyst
The mono olefins are conveterd to Linear alkyl benzene (LAB) while diolefins are conveterd to Heavy alkyl Benzene (HAB) The aromatics are extracted in counter current extraction of HF acid and are separated in distillation column called Acid regenerators
HF acid catalyst
R- CH = CH ndashCH2 ndash Rrsquo + Benzene R-CH-CH2-CH2-Rrsquo
M Olefins
Where R and Rrsquo are alkyl groups (CH3) LAB
R-CH=CH-CH=CH-Rrsquo + 2 Benzene Heavy alkyl benzene
Di olefins HAB
The reaction is instantaneous and carried through a two stage mixer settler system The reactor section effluent is then processed in series of distillation columns where excess Benzene Paraffin LAB and byproduct Heavy alkyl benzene (HAB) gets separated
The separated benzene is recycled back to HF alkylation reactor while separated Paraffin is recycled to Pacol reactor for reaction The product Linear alkyl benzene (LAB) and byproduct Heavy alkyl benzene (HAB) are send to storage
The aromatics and non-normal which are formed in Pacol reaction are extracted in HF reaction unit by counter current extraction of HF acid as POLYMER This polymer is separated in Acid regenerators and then neutralized with KOH and send to storage
Block Diagram of Alkylation process
17 of 72
PROCESS INPUTS amp OUTPUTS
18 of 72
As described earlier plant is divided into two sections
a) Front End for Normal paraffin production from Keroseneb) Back End for Linear alkyl Benzene (LAB) production from N paraffin
The raw material kerosene is supplied to the plant from two sources
a) From Bharat Petroleum Corp Ltd Chembur (BPCL) via 55 Km pipelineb) From Reliance Petroleum Ltd Jamnagar via Shipping
The light kerosene heavy kerosene and Raffinate from front end are combined and send as return kerosene via pipeline or shipping to either BPCL or to RPL Jamnagar
The manufacturing of LAB is done in two grades
a) Domestic grade (Molecular weight 235 to 239)b) Export grade (Molecular weight 239 to 240)
The byproducts of LAB plant are
a) Light Normal paraffinb) Heavy normal paraffinc) Heavy alkyl Benzened) Tar polymer
Installed Capacities
A) For Normal Paraffin 115000 MT Highest prod 126596 MT in year 2001-2002
B) For LAB 100000 MT Highest prod 112484 MT in year 1999-2000
Plant load
A) For Normal Paraffin 117
B) For LAB 120 Production per day
A) For Normal Paraffin 330 MT day (Avrg)
B) For LAB 324 MTday (Avrg)
Customers
19 of 72
1) The Normal paraffin produced in LAB plant is normally used for captive consumption for producing LAB
2) The main customer of LAB is Ms Hindustan Lever and Procter amp Gamble Ltd and their subsidiary
3) The LAB is exported to Europe American African and Asian countries4) The light and Heavy normal paraffin is used to manufacture Chlorinated Paraffin Wax5) Heavy alkyl Benzene is used as lubricants in oil industry
Utility system in LAB plant
Hot oil system
There are two Hot oil Heaters available in LAB plant one for Front End and other is for Back End The Heaters are fired with furnace oil LSHS and off gases from process
The Hot oil (Dow Therm) which is thermic fluid is heated in these Hot oil heaters
The all heat inputs to the column preheater are given by circulating Hot oil at supply temperature of 330 DegC
Effluent System
The effluent generated in LAB plant mainly constitute
a) Fluoride Maximum limit lt 10 ppmb) Oil Maximum limit lt 10 ppm
For reduction of fluoride in effluent water LAB plant have two neutralisation basins where effluent from HF area is collected and then reacted with Lime (CaCO3) to reduce fluoride content below 10ppm
For reduction of oil in effluent water LAB plant have CPI separator installed to separate oil from effluent water The oil separated is send to Slope oil storage
In addition to this there is hydrocarbon pit installed in front end to collect pump and filter drains which is being blended in return kerosene to reduce oil load in effluent systemThere all oil collection pits installed in storm water channels to avoid oil going into the river via gates
20 of 72
Cooling water systemFor cooling the final products Byproducts to normal ambient temperatures the products byproducts are cooled in coolers The cooling media used is water There are three cooling towers installed in LAB planta) HF cooling tower it is separate cooling tower to avoid HF ingrace in coolers in non-HF
areab) Front End Cooling towerc) Back End cooling tower
Fin Fan coolers The distillation columns overheads are condensed in air-cooled fin fan coolers The advantage of these coolers over water-cooled coolers is low operating cost
Safety measures taken in LAB Plant
1) Safety Interlocks for tripping the operation of equipments in case process variables touches maximum allowable value
2) Flare system for burning excess gases from process3) Infra red detection system for Pacol Reactor and Hot pumps 4) Hydrocarbon detection system for detecting hydrocarbon leakages5) H2S detection system and siren for detecting H2S gas leakages 6) HF Detection system for detecting HF leakages7) Schedule HF leak testing of HF flanges8) Application of HF detection paints to all HF flanges to detect HF leak by decolouration9) Schedule Thickness survey of pipelines in HF area 10) Fire water sprinkler system for HF vessels Columns and pumps11) Fire water sprinkler system for Hot oil pumps12) Yellow boundary marking of HF area where personal protective equipments (PPErsquos) are
mandatory 13) Personal protective equipments (PPErsquos) for HF area Different types of PVC suits are defined
for different types of jobs ( A B C and D type)14) Separate breathing air reciprocating compressor for breathing air for C and D type PVC
suits in case of eemergency15) KOH scrubbing for venting from all HF equipments so that HF will not release into the
flare16) Daily Benzene monitoring with dragger tubes to detect any Benzene leaks from process17) Close draining system of HF and Benzene
21 of 72
PROJECT ndashI
The project is about developing a ldquoBENZENE-WATER WASHrdquo system to remove the impurities coming with fresh benzene that enters into benzene stripper and effects thefin-fan cooler The project is about developing such a scheme which will remove these impurities before entering the benzene stripper to eliminate the failure of fin-fan cooler
The scheme should also be such that it should not reduce the efficiency of the equipment and should be cost-effective
What is Benzene stripper
The high volatility of water dissolved in hydrocarbons is used in this column to obtain water-free benzene in the column bottoms which also removes any dissolved oxygen or non-condensibles in the benzene or off spec feeds Makeup benzene is fed to the overhead receiver on level control reset by the overhead receiver level controller It is refluxed via the overhead pump on flow control reset by the column bottom level controller and sent to the reaction section by the bottoms pump via the benzene stripper feedbottoms exchanger on flow control which is reset by the benzene column receiver level controller The benzene stripper receiver floats on the flare and is sized big enough to allow enough settling time for the water There is a small nitrogen flow via a conservation vent into the receiver vapor flare to maintain a slight nitrogen purge Water is collected in the boot and drained periodically whenever there is a boot high alarm Maintain a visible benzene water interface in the boot sight glass The benzene at the column bottom normally has a water content of less than 20ppm actually much lower if the column is operated well A moisture analyzer alarm high is provided The heat input to the column is provided by a hot oil reboiler with the hot oil flow controlled Off-spec material from the off-spec tank is normally rerun via the benzene stripper coming into the column receiver
What is the Issue
The benzene stripper column overheads are condensed in air-cooler (fin-fan coolers EC-301)The advantage of using this fin-fan cooler is the low operating cost no space constraint as are not on ground level etc This tube-bundle was failing at a frequency of once in a span of two years Failure analysis study was carried out and found that there are some impurities coming along with fresh benzene which are forming acidic solution after condensing in fin-fan This acidic solution formed was causing the repeated failure of tube-bundle
Water dosing was started upstream of the fin-fan bundle to dissolve out the impurities or to neutralize the acidic solution so that tubes can be saved This practice was started in 2008 Even after this modification the failures and continue and its difficult to analyze that what type of impurities are coming with benzene
22 of 72
So to eliminate this problem a scheme has been plotted to design a benzene scrubbing system This will be basically washing of benzene with DM water to remove the impurities before it enters the benzene stripper
The schematic diagram of this system is shown below
The scheme consists of a static mixture for mixing benzene and water for a particular residence time and at a particular velocity as required A gravity settler is for separating benzene and water on the basis of density difference
23 of 72
STATIC MIXER
This mixing device has no moving parts is simple and its cost can be quite reasonable when compared to mechanical driven mixers Static or motionless mixers are relatively new development and have proven to be effective for many specific and valuable process application It is useful for a wide range of viscosity fluids particularly useful in liquid-liquid mixing and also for some gas-liquid dispersion
The concept of motionless mixers is to achieve a uniform composition and temperature distribution in fluids flowing through the device The concept is build around a stationary rigid element placed in a pipe or cylinder that uses the energy of fluid flowing past to produce the mixing The unit becomes more efficient by adding additional static elements causing the flowing fluid elements to split rearrange recombine and split again to repeat the process lsquoxrsquo times for a uniform or homogeneous flowing stream is produced at discharge
Principle of operation
The static mixer unit is a series of fixed helical elements enclosed within a tubular housing
LIQUID ndash LIQUID SEPARATION(Decanters)
Separation of two liquid phases immiscible or partially miscible liquids is a common requirement in the process industries It is also frequently necessary to separate small quantities of entrained water from process streams The simplest form of equipment used to separate liquid phases is the gravity settling tank the decanter Various proprietary equipment is also used to promote coalescence and improve separation in difficult systems or where emulsions are likely to form Centrifugal separators are also used
Decanters (settlers)
Decanters are used to separate liquids where there is a sufficient difference in density between the liquids for the droplets to settle readily Decanters are essentially tanks which give sufficient residence time for the droplets of the dispersed phase to rise (or settle ) to the interface between the phases and coalesce
In an operating decanter there will be three distinct zones or bands clear heavy liquid separating dispersed liquid (the dispersion zone) and clear light liquid The position of the interface can be controlled with or without the use of instruments by use of a siphon take-off for the heavy liquid
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Vertical decanter
The height of the take-off can be determined by making a pressure balance Neglecting friction loss in the pipes the pressure exerted by the combined height of the heavy and light liquid in the vessel must be balanced by the height of the heavy liquid in the take-off leg
(z1-z3)Ρ1g + z3 Ρ2g= z2 Ρ2g
z2 = (z1-z3) Ρ1 + z3 (1)Ρ2
WhereZ1= height from datum to light liquid overflow m Z2=height from datum to heavy liquid overflow m Z3=height from datum to interface m Ρ1=density of the light liquid kgmsup3 Ρ2=density of the heavy liquid kg msup3
The height of the liquid interface should be measured accurately when the liquid densities are close when one component is present only in small quantities or when the throughput is very small A typical scheme for the automatic control of the interface using a level instrument that can detect the position of the interface is shown in the diagram below Where one phase is present only in small amounts it is often recycled to the decanter feed to give more stable operation
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CALCULATIONS
STATIC MIXER DESIGN
Required data
1 Physical properties of materials Density kgmsup3
Viscosity Pas = 0001Cp
2 Pressure drop Pressure drop in static mixer is best described by comparison with pipe flow
3 Geometrical parameters Diameter m
Type of static mixer constant (k)
Length (l) m
4 Process variables
Flow rate msup3s TemperaturedegC Pressure bar
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Pressure drop calculation
a) Velocity (v)
V = Qπ4 Dsup2
b) Reynoldsrsquos number(Re)
Re= dvρμ
c) Pressure drop (Δp)For Re lt50 Δp =k1x μ x l xQd dsup3
k1= laminar flow constant
For Re gt10sup3 Δp =k2 x ρ x l x vsup2d 2
= k2 x Q x l x 8 x Qsup2d prodsup2 d⁴
k2= turbulent flow constant
Pipe diameter Flow seems to be turbulent as both the materials (B2+ H2O) are not viscous
D =39Q ⁰ ⁴⁵ ρ sup1sup3⁰
Q =52 + 572 = 1092msup3hr = 303 x 10macrsup3msup3s= 38564 ftsup3hr
Ρ = 926328 kgmsup3 =57828 lbftsup3
D =39 x Q ⁰ ⁴⁵ x ρ sup1sup3⁰
D =39 x (38564) ⁰ ⁴⁵ x (57828) sup1sup3⁰ 3600
D= 24 inch = 25 inch = 00635m
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Velocity(v)
V =4 Q proddsup2
= 303 x 10macrsup3 msup3s x 4 314 x (00635)sup2
= 0957 ms (approx 1ms)
Reynoldrsquosnumber(Re)
Re = dvρ Μ = 00635 x 1 x 926328 0572
Re =103 x 10⁵
Thus the flow is highly turbulent
Flow regime Reynoldrsquos no(Re)
No of element No of elements to add if viscosity ratio between fluids exceeds 10001
No of elements to add if volumetric ratio between fluids exceeds 1001
Laminar lt1 24 6 61-10 18 6 611-50 14 6 651-100 12 6 6101-500 10 6 6
Transitional 501-1000 8 4 41001-2000 6 4 4
Turbulent 2001-5000 4 2 25001+ 2 2 2
Thus from the above table the mixer will have 2 elements
The mixer length will be based on the number of elements required An approximate length can be determined by multiplying the number of elements by 15
Mixer length = 15 x 2 =3
28 of 72
For turbulent flow applications it is generally recommended that a minimum velocity of 10 ftsec be maintained
V= 0408 x QDsup2 = 0408 x 4813sup2 = 218 ftsec =066 ms
DECANTER DESIGN
Benzene Water
Flow rate (msup3h) 52 572
Flow rate (kgh) 4543812 570311
Density (kgmsup3) 87381 99704
Viscosity (Pas) 0000604 000089
Take Dd = 150microm
microd = (150 Х 10ˉ⁶)sup2 Х 981 Х (87381-99704) 18 Х 000089
microd = -169787 Х 10ˉsup3 ms = -17 mms (rising)
As the flow rate is small we will use a vertical cylindrical vessel
The decanter vessel is sized on the basis that the velocity of the continuous phase must be less than settling velocity of the droplets of the dispersed phase Plug flow is assumed and the velocity of the continuous phase calculated using the area of the interfacemicroc =Lclt microdAiWhere microd = settling velocity of the dispersed phase droplets msmicroc = velocity of the continuous phase msLc = continuous phase volumetric flow rate msup3sAi = area of the interface msup2
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Lc = 570311 X 1 99704 3600
= 00015889 msup3s
Ai=Lc = 00015889 microc 00017
= 0935817588 msup2
For a vertical cylindrical decanterAi = prodrsup2
r = 0935817588 prodr = 0545835318 m
Diameter= 1091670637 m
Taking the height as twice the diameter a reasonable value for a cylinder
Height = 2183341274 m
The position of the interface should be such that the band of droplets that collect at the interface waiting to coalesce and cross the interface does not extend to the bottom (or top) of the vessel The depth of the dispersion band is a function of the liquid flow rate and the interfacial area A value of to per cent of the decanter height is usually taken for the design purposes
Take the dispersion band as 10 per cent of the height = 021833mThe residence time of the droplets in the dispersion band = 021833 = 021833microd 00017 =1285926 s (approx 2 min)
This is satisfactory time a time of 2 to 5 min is normally recommended Thus the size of the water (continuous heavy phase) droplets that could be entrained with benzene (light phase) will be
Velocity of benzene phase = 4543812 X 1 X 1 873811 3600093581
=0001543511 ms =1543511mms
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So from equation ( ) So the entrained droplet size will be =00015435 X 18 X 0000604 frac12 981 X (99704-873812)
=00001178 m=1178 microm
which is satisfactory below 150 microm
Piping arrangement
To minimize entrainment by the jet of liquid entering the vessel the inlet velocity for a decanter should keep below 1 ms
The velocity from static mixer= 066 ms
Flow rate= 4543812 + 570311 X 1 87381 99704 3600
= 0003033345msup3s
Area of pipe= flow ratevelocity
= 0003033345066
= 0004554572msup2
Pipe diameter =0004554572 x 4prod
= 0076158749 m =29983 inch (approx 3 in)
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PROJECT II
CALULATING THE DEW POINT
This project is about the study and evaluation of the performance of the compressors in the Hydrobon section of the LAB plant which is installed to optimize the purity of hydrogen coming from the product separators The compressors in this section include recycle gas compressor and make-up gas compressorThe purity of hydrogen can be increased upto 90
This project will give the company an overall view of this loop The plant is running well about its installed capacity(131-140) The company wants to retain the purity level of nearly 90 for hydrogen even after operating above installed capacity Hence the current project will give the company an idea of the current hydrogen quality(purity) which is obtained and give an idea about changes if any to be made to existing process set-up
HYDROBON REACTOR
Hydrobon reactor is designed to remove contaminants present in the raw kerosene without changing the boiling range The hydrocarbon is passed through a 2 bed reactor feed with S 12 catalyst through a feed effluent exchanger and charge heater which maintain the required reaction temperature(310 c) The reaction required hydrogen gas which is supplied from pacol net gas generated from back end and tattoray hydrogen from PX plantThe reaction charge is heated to the reaction temperature in the charge heater enters the reactor from the top and is distributed over the catalyst bed Catalytic hydrogenation takes place in the reactor The impurities react with hydrogen and form salts which are subsequently separated and finally removed in sour water stripper The reactor effluents after separation is fed to the product stripper to remove lighters and hydrotreated kerosene is fed to molex unit The sulfur and nitrogen levels are reduced to 1 ppm or less
PARAMETERS DESIGN ACTUALPlant load() 100 115Hydrobon feed rate(mthr) 58 60Temperature 416 310Pressure (kgcm2 g) 822 62H2HC ratio 385 460Recycle hydrogen purity(mole)
75 min 95
Hydrobon feed specificationa Bromine
index(mg100gm)800 800
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b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
39 of 72
HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
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4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
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FLOW DIAGRAM OF HYDROBON SECTION
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Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
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nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
44 of 72
Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
45 of 72
DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
47 of 72
ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
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Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
49 of 72
Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
50 of 72
Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
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=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
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Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
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Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
54 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
55 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
CHAMBER
CHAMBER
ROTARY VALVE
EXTRACT
RAFFINATE
Normal paraffin Non Normal
There are two adsorption chambers with 24 beds The process simulates countercurrent contact between fixed bed adsorbent and feed stream This simulation is done by flow directing device called ldquoRotary valverdquo
The separated streams from Molex chambers containing normal paraffin (Extract) and non normal (Raffinate) are fed to two distillation columns a) Extract column and b) Raffinate column In both distillation columns desorbent is separated from top and sidecut and recycled for desorption While bottom product of Extract column is Normal paraffin send to storage
E R
F
D
13 of 72
STRIPPER
RERUN
Heart cut Paraffin (C10 to C13)
Light NP
Feed NP
Heavy NP
2) Back EndAs described earlier Linear alkyl benzene (LAB) is produced from linear olefins by UOP detergent alkylation process The raw material normal paraffin of C10 to C14 from front end is processed in back end in series of processes they are
a) Prefractionation b) Pacol c) Alkylation
a) PREFRACTIONATION The normal paraffin of C10 to C14 carbon range is separated to Normal paraffin of C10 to C13 carbon range in two distillation columns in series
1) Stripper column In this distillation column lighter compound (if any) and partly C10 paraffin is removed as light normal paraffin (LNP) from top This LNP is sold in market as byproduct The bottoms is send to Rerun column
2) Rerun ColumnIn this column heartcut paraffin (C10 to C13) is separated from top as distillate The bottoms containing mainly C14 paraffin is sold in market as heavy normal paraffin (HNP) as byproduct
14 of 72
b) PACOL (Paraffin converted to olefin)
The normal paraffin of carbon range C10 to C13 is converted to linear olefins of carbon range C10 to C13 by Dehydrogenation reaction in UOP Pacol process
The catalyst used in reactor is alumina based platinum catalyst
Platinum catalyst
CH3-C-C-C-CH3 CH3 - C = C ndash C ndash CH3 + H2
N paraffin Linear Mono olefins
There are some side reactions takes places in Pacol they are
CH3 - C = C ndash C ndash CH3 CH3 - C = C = C ndash CH3 + H2
Linear Mono olefins Linear Di olefins
CH3 - C = C = C ndash CH3 Aromatics + H2
Linear Di olefins
As it is dehydrogenation reaction H2 gas is separated from reactor effluent in contact condenser and send to Front End for Hydrobon makeup gas compressor
Cracking also takes place in reactor where ltC10 paraffin and olefins are formed which is removed in distillation column called Pacol stripper The gas separated in stripper is burnt in heater as off gases
The reaction temperature is 470 to 495 DegC while pressure is kept low at 13 kgcm2g
The life of pacol catalyst is about 30 to 40 days As life of the catalyst is low there are two pacol reactors for continuous running of the plant
The conversion of paraffin is about 12 to 13
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ContactCondenser
PACOL
STPR
Lighters andOff gases
Pacol reactor
To Alkylation
Charge heater
Normal ParaffinFeed
H2 to front end
DEFINE UNIT
The main purpose of this unit is to increase overall yield of LAB The Diolefins formed in Pacol reaction is converted to Mono olefins and normal paraffin thereby generating more LAB and lesser byproducts
The catalyst used in this reactor is Nickel based on alumina
Nickel catalyst
Diolefins + H2 Mono olefins
Diolefins + H2 Normal Paraffin
The reaction temperature is 180 DegC and pressure is 140 Kgcm2g
Block Diagram of Pacol Unit
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IMIXER
2MIXER
HFSTRIPPER
C) ALKYLATION
As described earlier linear olefins (C10 to C13) are alkylated in this unit to form Linear alkyl Benzene (LAB) in presence of HF acid catalyst
The mono olefins are conveterd to Linear alkyl benzene (LAB) while diolefins are conveterd to Heavy alkyl Benzene (HAB) The aromatics are extracted in counter current extraction of HF acid and are separated in distillation column called Acid regenerators
HF acid catalyst
R- CH = CH ndashCH2 ndash Rrsquo + Benzene R-CH-CH2-CH2-Rrsquo
M Olefins
Where R and Rrsquo are alkyl groups (CH3) LAB
R-CH=CH-CH=CH-Rrsquo + 2 Benzene Heavy alkyl benzene
Di olefins HAB
The reaction is instantaneous and carried through a two stage mixer settler system The reactor section effluent is then processed in series of distillation columns where excess Benzene Paraffin LAB and byproduct Heavy alkyl benzene (HAB) gets separated
The separated benzene is recycled back to HF alkylation reactor while separated Paraffin is recycled to Pacol reactor for reaction The product Linear alkyl benzene (LAB) and byproduct Heavy alkyl benzene (HAB) are send to storage
The aromatics and non-normal which are formed in Pacol reaction are extracted in HF reaction unit by counter current extraction of HF acid as POLYMER This polymer is separated in Acid regenerators and then neutralized with KOH and send to storage
Block Diagram of Alkylation process
17 of 72
PROCESS INPUTS amp OUTPUTS
18 of 72
As described earlier plant is divided into two sections
a) Front End for Normal paraffin production from Keroseneb) Back End for Linear alkyl Benzene (LAB) production from N paraffin
The raw material kerosene is supplied to the plant from two sources
a) From Bharat Petroleum Corp Ltd Chembur (BPCL) via 55 Km pipelineb) From Reliance Petroleum Ltd Jamnagar via Shipping
The light kerosene heavy kerosene and Raffinate from front end are combined and send as return kerosene via pipeline or shipping to either BPCL or to RPL Jamnagar
The manufacturing of LAB is done in two grades
a) Domestic grade (Molecular weight 235 to 239)b) Export grade (Molecular weight 239 to 240)
The byproducts of LAB plant are
a) Light Normal paraffinb) Heavy normal paraffinc) Heavy alkyl Benzened) Tar polymer
Installed Capacities
A) For Normal Paraffin 115000 MT Highest prod 126596 MT in year 2001-2002
B) For LAB 100000 MT Highest prod 112484 MT in year 1999-2000
Plant load
A) For Normal Paraffin 117
B) For LAB 120 Production per day
A) For Normal Paraffin 330 MT day (Avrg)
B) For LAB 324 MTday (Avrg)
Customers
19 of 72
1) The Normal paraffin produced in LAB plant is normally used for captive consumption for producing LAB
2) The main customer of LAB is Ms Hindustan Lever and Procter amp Gamble Ltd and their subsidiary
3) The LAB is exported to Europe American African and Asian countries4) The light and Heavy normal paraffin is used to manufacture Chlorinated Paraffin Wax5) Heavy alkyl Benzene is used as lubricants in oil industry
Utility system in LAB plant
Hot oil system
There are two Hot oil Heaters available in LAB plant one for Front End and other is for Back End The Heaters are fired with furnace oil LSHS and off gases from process
The Hot oil (Dow Therm) which is thermic fluid is heated in these Hot oil heaters
The all heat inputs to the column preheater are given by circulating Hot oil at supply temperature of 330 DegC
Effluent System
The effluent generated in LAB plant mainly constitute
a) Fluoride Maximum limit lt 10 ppmb) Oil Maximum limit lt 10 ppm
For reduction of fluoride in effluent water LAB plant have two neutralisation basins where effluent from HF area is collected and then reacted with Lime (CaCO3) to reduce fluoride content below 10ppm
For reduction of oil in effluent water LAB plant have CPI separator installed to separate oil from effluent water The oil separated is send to Slope oil storage
In addition to this there is hydrocarbon pit installed in front end to collect pump and filter drains which is being blended in return kerosene to reduce oil load in effluent systemThere all oil collection pits installed in storm water channels to avoid oil going into the river via gates
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Cooling water systemFor cooling the final products Byproducts to normal ambient temperatures the products byproducts are cooled in coolers The cooling media used is water There are three cooling towers installed in LAB planta) HF cooling tower it is separate cooling tower to avoid HF ingrace in coolers in non-HF
areab) Front End Cooling towerc) Back End cooling tower
Fin Fan coolers The distillation columns overheads are condensed in air-cooled fin fan coolers The advantage of these coolers over water-cooled coolers is low operating cost
Safety measures taken in LAB Plant
1) Safety Interlocks for tripping the operation of equipments in case process variables touches maximum allowable value
2) Flare system for burning excess gases from process3) Infra red detection system for Pacol Reactor and Hot pumps 4) Hydrocarbon detection system for detecting hydrocarbon leakages5) H2S detection system and siren for detecting H2S gas leakages 6) HF Detection system for detecting HF leakages7) Schedule HF leak testing of HF flanges8) Application of HF detection paints to all HF flanges to detect HF leak by decolouration9) Schedule Thickness survey of pipelines in HF area 10) Fire water sprinkler system for HF vessels Columns and pumps11) Fire water sprinkler system for Hot oil pumps12) Yellow boundary marking of HF area where personal protective equipments (PPErsquos) are
mandatory 13) Personal protective equipments (PPErsquos) for HF area Different types of PVC suits are defined
for different types of jobs ( A B C and D type)14) Separate breathing air reciprocating compressor for breathing air for C and D type PVC
suits in case of eemergency15) KOH scrubbing for venting from all HF equipments so that HF will not release into the
flare16) Daily Benzene monitoring with dragger tubes to detect any Benzene leaks from process17) Close draining system of HF and Benzene
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PROJECT ndashI
The project is about developing a ldquoBENZENE-WATER WASHrdquo system to remove the impurities coming with fresh benzene that enters into benzene stripper and effects thefin-fan cooler The project is about developing such a scheme which will remove these impurities before entering the benzene stripper to eliminate the failure of fin-fan cooler
The scheme should also be such that it should not reduce the efficiency of the equipment and should be cost-effective
What is Benzene stripper
The high volatility of water dissolved in hydrocarbons is used in this column to obtain water-free benzene in the column bottoms which also removes any dissolved oxygen or non-condensibles in the benzene or off spec feeds Makeup benzene is fed to the overhead receiver on level control reset by the overhead receiver level controller It is refluxed via the overhead pump on flow control reset by the column bottom level controller and sent to the reaction section by the bottoms pump via the benzene stripper feedbottoms exchanger on flow control which is reset by the benzene column receiver level controller The benzene stripper receiver floats on the flare and is sized big enough to allow enough settling time for the water There is a small nitrogen flow via a conservation vent into the receiver vapor flare to maintain a slight nitrogen purge Water is collected in the boot and drained periodically whenever there is a boot high alarm Maintain a visible benzene water interface in the boot sight glass The benzene at the column bottom normally has a water content of less than 20ppm actually much lower if the column is operated well A moisture analyzer alarm high is provided The heat input to the column is provided by a hot oil reboiler with the hot oil flow controlled Off-spec material from the off-spec tank is normally rerun via the benzene stripper coming into the column receiver
What is the Issue
The benzene stripper column overheads are condensed in air-cooler (fin-fan coolers EC-301)The advantage of using this fin-fan cooler is the low operating cost no space constraint as are not on ground level etc This tube-bundle was failing at a frequency of once in a span of two years Failure analysis study was carried out and found that there are some impurities coming along with fresh benzene which are forming acidic solution after condensing in fin-fan This acidic solution formed was causing the repeated failure of tube-bundle
Water dosing was started upstream of the fin-fan bundle to dissolve out the impurities or to neutralize the acidic solution so that tubes can be saved This practice was started in 2008 Even after this modification the failures and continue and its difficult to analyze that what type of impurities are coming with benzene
22 of 72
So to eliminate this problem a scheme has been plotted to design a benzene scrubbing system This will be basically washing of benzene with DM water to remove the impurities before it enters the benzene stripper
The schematic diagram of this system is shown below
The scheme consists of a static mixture for mixing benzene and water for a particular residence time and at a particular velocity as required A gravity settler is for separating benzene and water on the basis of density difference
23 of 72
STATIC MIXER
This mixing device has no moving parts is simple and its cost can be quite reasonable when compared to mechanical driven mixers Static or motionless mixers are relatively new development and have proven to be effective for many specific and valuable process application It is useful for a wide range of viscosity fluids particularly useful in liquid-liquid mixing and also for some gas-liquid dispersion
The concept of motionless mixers is to achieve a uniform composition and temperature distribution in fluids flowing through the device The concept is build around a stationary rigid element placed in a pipe or cylinder that uses the energy of fluid flowing past to produce the mixing The unit becomes more efficient by adding additional static elements causing the flowing fluid elements to split rearrange recombine and split again to repeat the process lsquoxrsquo times for a uniform or homogeneous flowing stream is produced at discharge
Principle of operation
The static mixer unit is a series of fixed helical elements enclosed within a tubular housing
LIQUID ndash LIQUID SEPARATION(Decanters)
Separation of two liquid phases immiscible or partially miscible liquids is a common requirement in the process industries It is also frequently necessary to separate small quantities of entrained water from process streams The simplest form of equipment used to separate liquid phases is the gravity settling tank the decanter Various proprietary equipment is also used to promote coalescence and improve separation in difficult systems or where emulsions are likely to form Centrifugal separators are also used
Decanters (settlers)
Decanters are used to separate liquids where there is a sufficient difference in density between the liquids for the droplets to settle readily Decanters are essentially tanks which give sufficient residence time for the droplets of the dispersed phase to rise (or settle ) to the interface between the phases and coalesce
In an operating decanter there will be three distinct zones or bands clear heavy liquid separating dispersed liquid (the dispersion zone) and clear light liquid The position of the interface can be controlled with or without the use of instruments by use of a siphon take-off for the heavy liquid
24 of 72
Vertical decanter
The height of the take-off can be determined by making a pressure balance Neglecting friction loss in the pipes the pressure exerted by the combined height of the heavy and light liquid in the vessel must be balanced by the height of the heavy liquid in the take-off leg
(z1-z3)Ρ1g + z3 Ρ2g= z2 Ρ2g
z2 = (z1-z3) Ρ1 + z3 (1)Ρ2
WhereZ1= height from datum to light liquid overflow m Z2=height from datum to heavy liquid overflow m Z3=height from datum to interface m Ρ1=density of the light liquid kgmsup3 Ρ2=density of the heavy liquid kg msup3
The height of the liquid interface should be measured accurately when the liquid densities are close when one component is present only in small quantities or when the throughput is very small A typical scheme for the automatic control of the interface using a level instrument that can detect the position of the interface is shown in the diagram below Where one phase is present only in small amounts it is often recycled to the decanter feed to give more stable operation
25 of 72
CALCULATIONS
STATIC MIXER DESIGN
Required data
1 Physical properties of materials Density kgmsup3
Viscosity Pas = 0001Cp
2 Pressure drop Pressure drop in static mixer is best described by comparison with pipe flow
3 Geometrical parameters Diameter m
Type of static mixer constant (k)
Length (l) m
4 Process variables
Flow rate msup3s TemperaturedegC Pressure bar
26 of 72
Pressure drop calculation
a) Velocity (v)
V = Qπ4 Dsup2
b) Reynoldsrsquos number(Re)
Re= dvρμ
c) Pressure drop (Δp)For Re lt50 Δp =k1x μ x l xQd dsup3
k1= laminar flow constant
For Re gt10sup3 Δp =k2 x ρ x l x vsup2d 2
= k2 x Q x l x 8 x Qsup2d prodsup2 d⁴
k2= turbulent flow constant
Pipe diameter Flow seems to be turbulent as both the materials (B2+ H2O) are not viscous
D =39Q ⁰ ⁴⁵ ρ sup1sup3⁰
Q =52 + 572 = 1092msup3hr = 303 x 10macrsup3msup3s= 38564 ftsup3hr
Ρ = 926328 kgmsup3 =57828 lbftsup3
D =39 x Q ⁰ ⁴⁵ x ρ sup1sup3⁰
D =39 x (38564) ⁰ ⁴⁵ x (57828) sup1sup3⁰ 3600
D= 24 inch = 25 inch = 00635m
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Velocity(v)
V =4 Q proddsup2
= 303 x 10macrsup3 msup3s x 4 314 x (00635)sup2
= 0957 ms (approx 1ms)
Reynoldrsquosnumber(Re)
Re = dvρ Μ = 00635 x 1 x 926328 0572
Re =103 x 10⁵
Thus the flow is highly turbulent
Flow regime Reynoldrsquos no(Re)
No of element No of elements to add if viscosity ratio between fluids exceeds 10001
No of elements to add if volumetric ratio between fluids exceeds 1001
Laminar lt1 24 6 61-10 18 6 611-50 14 6 651-100 12 6 6101-500 10 6 6
Transitional 501-1000 8 4 41001-2000 6 4 4
Turbulent 2001-5000 4 2 25001+ 2 2 2
Thus from the above table the mixer will have 2 elements
The mixer length will be based on the number of elements required An approximate length can be determined by multiplying the number of elements by 15
Mixer length = 15 x 2 =3
28 of 72
For turbulent flow applications it is generally recommended that a minimum velocity of 10 ftsec be maintained
V= 0408 x QDsup2 = 0408 x 4813sup2 = 218 ftsec =066 ms
DECANTER DESIGN
Benzene Water
Flow rate (msup3h) 52 572
Flow rate (kgh) 4543812 570311
Density (kgmsup3) 87381 99704
Viscosity (Pas) 0000604 000089
Take Dd = 150microm
microd = (150 Х 10ˉ⁶)sup2 Х 981 Х (87381-99704) 18 Х 000089
microd = -169787 Х 10ˉsup3 ms = -17 mms (rising)
As the flow rate is small we will use a vertical cylindrical vessel
The decanter vessel is sized on the basis that the velocity of the continuous phase must be less than settling velocity of the droplets of the dispersed phase Plug flow is assumed and the velocity of the continuous phase calculated using the area of the interfacemicroc =Lclt microdAiWhere microd = settling velocity of the dispersed phase droplets msmicroc = velocity of the continuous phase msLc = continuous phase volumetric flow rate msup3sAi = area of the interface msup2
29 of 72
Lc = 570311 X 1 99704 3600
= 00015889 msup3s
Ai=Lc = 00015889 microc 00017
= 0935817588 msup2
For a vertical cylindrical decanterAi = prodrsup2
r = 0935817588 prodr = 0545835318 m
Diameter= 1091670637 m
Taking the height as twice the diameter a reasonable value for a cylinder
Height = 2183341274 m
The position of the interface should be such that the band of droplets that collect at the interface waiting to coalesce and cross the interface does not extend to the bottom (or top) of the vessel The depth of the dispersion band is a function of the liquid flow rate and the interfacial area A value of to per cent of the decanter height is usually taken for the design purposes
Take the dispersion band as 10 per cent of the height = 021833mThe residence time of the droplets in the dispersion band = 021833 = 021833microd 00017 =1285926 s (approx 2 min)
This is satisfactory time a time of 2 to 5 min is normally recommended Thus the size of the water (continuous heavy phase) droplets that could be entrained with benzene (light phase) will be
Velocity of benzene phase = 4543812 X 1 X 1 873811 3600093581
=0001543511 ms =1543511mms
30 of 72
So from equation ( ) So the entrained droplet size will be =00015435 X 18 X 0000604 frac12 981 X (99704-873812)
=00001178 m=1178 microm
which is satisfactory below 150 microm
Piping arrangement
To minimize entrainment by the jet of liquid entering the vessel the inlet velocity for a decanter should keep below 1 ms
The velocity from static mixer= 066 ms
Flow rate= 4543812 + 570311 X 1 87381 99704 3600
= 0003033345msup3s
Area of pipe= flow ratevelocity
= 0003033345066
= 0004554572msup2
Pipe diameter =0004554572 x 4prod
= 0076158749 m =29983 inch (approx 3 in)
31 of 72
32 of 72
33 of 72
34 of 72
35 of 72
36 of 72
37 of 72
PROJECT II
CALULATING THE DEW POINT
This project is about the study and evaluation of the performance of the compressors in the Hydrobon section of the LAB plant which is installed to optimize the purity of hydrogen coming from the product separators The compressors in this section include recycle gas compressor and make-up gas compressorThe purity of hydrogen can be increased upto 90
This project will give the company an overall view of this loop The plant is running well about its installed capacity(131-140) The company wants to retain the purity level of nearly 90 for hydrogen even after operating above installed capacity Hence the current project will give the company an idea of the current hydrogen quality(purity) which is obtained and give an idea about changes if any to be made to existing process set-up
HYDROBON REACTOR
Hydrobon reactor is designed to remove contaminants present in the raw kerosene without changing the boiling range The hydrocarbon is passed through a 2 bed reactor feed with S 12 catalyst through a feed effluent exchanger and charge heater which maintain the required reaction temperature(310 c) The reaction required hydrogen gas which is supplied from pacol net gas generated from back end and tattoray hydrogen from PX plantThe reaction charge is heated to the reaction temperature in the charge heater enters the reactor from the top and is distributed over the catalyst bed Catalytic hydrogenation takes place in the reactor The impurities react with hydrogen and form salts which are subsequently separated and finally removed in sour water stripper The reactor effluents after separation is fed to the product stripper to remove lighters and hydrotreated kerosene is fed to molex unit The sulfur and nitrogen levels are reduced to 1 ppm or less
PARAMETERS DESIGN ACTUALPlant load() 100 115Hydrobon feed rate(mthr) 58 60Temperature 416 310Pressure (kgcm2 g) 822 62H2HC ratio 385 460Recycle hydrogen purity(mole)
75 min 95
Hydrobon feed specificationa Bromine
index(mg100gm)800 800
38 of 72
b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
39 of 72
HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
40 of 72
4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
41 of 72
FLOW DIAGRAM OF HYDROBON SECTION
42 of 72
Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
43 of 72
nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
44 of 72
Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
45 of 72
DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
46 of 72
DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
47 of 72
ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
48 of 72
Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
49 of 72
Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
50 of 72
Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
51 of 72
=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
52 of 72
Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
53 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
54 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
55 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
STRIPPER
RERUN
Heart cut Paraffin (C10 to C13)
Light NP
Feed NP
Heavy NP
2) Back EndAs described earlier Linear alkyl benzene (LAB) is produced from linear olefins by UOP detergent alkylation process The raw material normal paraffin of C10 to C14 from front end is processed in back end in series of processes they are
a) Prefractionation b) Pacol c) Alkylation
a) PREFRACTIONATION The normal paraffin of C10 to C14 carbon range is separated to Normal paraffin of C10 to C13 carbon range in two distillation columns in series
1) Stripper column In this distillation column lighter compound (if any) and partly C10 paraffin is removed as light normal paraffin (LNP) from top This LNP is sold in market as byproduct The bottoms is send to Rerun column
2) Rerun ColumnIn this column heartcut paraffin (C10 to C13) is separated from top as distillate The bottoms containing mainly C14 paraffin is sold in market as heavy normal paraffin (HNP) as byproduct
14 of 72
b) PACOL (Paraffin converted to olefin)
The normal paraffin of carbon range C10 to C13 is converted to linear olefins of carbon range C10 to C13 by Dehydrogenation reaction in UOP Pacol process
The catalyst used in reactor is alumina based platinum catalyst
Platinum catalyst
CH3-C-C-C-CH3 CH3 - C = C ndash C ndash CH3 + H2
N paraffin Linear Mono olefins
There are some side reactions takes places in Pacol they are
CH3 - C = C ndash C ndash CH3 CH3 - C = C = C ndash CH3 + H2
Linear Mono olefins Linear Di olefins
CH3 - C = C = C ndash CH3 Aromatics + H2
Linear Di olefins
As it is dehydrogenation reaction H2 gas is separated from reactor effluent in contact condenser and send to Front End for Hydrobon makeup gas compressor
Cracking also takes place in reactor where ltC10 paraffin and olefins are formed which is removed in distillation column called Pacol stripper The gas separated in stripper is burnt in heater as off gases
The reaction temperature is 470 to 495 DegC while pressure is kept low at 13 kgcm2g
The life of pacol catalyst is about 30 to 40 days As life of the catalyst is low there are two pacol reactors for continuous running of the plant
The conversion of paraffin is about 12 to 13
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ContactCondenser
PACOL
STPR
Lighters andOff gases
Pacol reactor
To Alkylation
Charge heater
Normal ParaffinFeed
H2 to front end
DEFINE UNIT
The main purpose of this unit is to increase overall yield of LAB The Diolefins formed in Pacol reaction is converted to Mono olefins and normal paraffin thereby generating more LAB and lesser byproducts
The catalyst used in this reactor is Nickel based on alumina
Nickel catalyst
Diolefins + H2 Mono olefins
Diolefins + H2 Normal Paraffin
The reaction temperature is 180 DegC and pressure is 140 Kgcm2g
Block Diagram of Pacol Unit
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IMIXER
2MIXER
HFSTRIPPER
C) ALKYLATION
As described earlier linear olefins (C10 to C13) are alkylated in this unit to form Linear alkyl Benzene (LAB) in presence of HF acid catalyst
The mono olefins are conveterd to Linear alkyl benzene (LAB) while diolefins are conveterd to Heavy alkyl Benzene (HAB) The aromatics are extracted in counter current extraction of HF acid and are separated in distillation column called Acid regenerators
HF acid catalyst
R- CH = CH ndashCH2 ndash Rrsquo + Benzene R-CH-CH2-CH2-Rrsquo
M Olefins
Where R and Rrsquo are alkyl groups (CH3) LAB
R-CH=CH-CH=CH-Rrsquo + 2 Benzene Heavy alkyl benzene
Di olefins HAB
The reaction is instantaneous and carried through a two stage mixer settler system The reactor section effluent is then processed in series of distillation columns where excess Benzene Paraffin LAB and byproduct Heavy alkyl benzene (HAB) gets separated
The separated benzene is recycled back to HF alkylation reactor while separated Paraffin is recycled to Pacol reactor for reaction The product Linear alkyl benzene (LAB) and byproduct Heavy alkyl benzene (HAB) are send to storage
The aromatics and non-normal which are formed in Pacol reaction are extracted in HF reaction unit by counter current extraction of HF acid as POLYMER This polymer is separated in Acid regenerators and then neutralized with KOH and send to storage
Block Diagram of Alkylation process
17 of 72
PROCESS INPUTS amp OUTPUTS
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As described earlier plant is divided into two sections
a) Front End for Normal paraffin production from Keroseneb) Back End for Linear alkyl Benzene (LAB) production from N paraffin
The raw material kerosene is supplied to the plant from two sources
a) From Bharat Petroleum Corp Ltd Chembur (BPCL) via 55 Km pipelineb) From Reliance Petroleum Ltd Jamnagar via Shipping
The light kerosene heavy kerosene and Raffinate from front end are combined and send as return kerosene via pipeline or shipping to either BPCL or to RPL Jamnagar
The manufacturing of LAB is done in two grades
a) Domestic grade (Molecular weight 235 to 239)b) Export grade (Molecular weight 239 to 240)
The byproducts of LAB plant are
a) Light Normal paraffinb) Heavy normal paraffinc) Heavy alkyl Benzened) Tar polymer
Installed Capacities
A) For Normal Paraffin 115000 MT Highest prod 126596 MT in year 2001-2002
B) For LAB 100000 MT Highest prod 112484 MT in year 1999-2000
Plant load
A) For Normal Paraffin 117
B) For LAB 120 Production per day
A) For Normal Paraffin 330 MT day (Avrg)
B) For LAB 324 MTday (Avrg)
Customers
19 of 72
1) The Normal paraffin produced in LAB plant is normally used for captive consumption for producing LAB
2) The main customer of LAB is Ms Hindustan Lever and Procter amp Gamble Ltd and their subsidiary
3) The LAB is exported to Europe American African and Asian countries4) The light and Heavy normal paraffin is used to manufacture Chlorinated Paraffin Wax5) Heavy alkyl Benzene is used as lubricants in oil industry
Utility system in LAB plant
Hot oil system
There are two Hot oil Heaters available in LAB plant one for Front End and other is for Back End The Heaters are fired with furnace oil LSHS and off gases from process
The Hot oil (Dow Therm) which is thermic fluid is heated in these Hot oil heaters
The all heat inputs to the column preheater are given by circulating Hot oil at supply temperature of 330 DegC
Effluent System
The effluent generated in LAB plant mainly constitute
a) Fluoride Maximum limit lt 10 ppmb) Oil Maximum limit lt 10 ppm
For reduction of fluoride in effluent water LAB plant have two neutralisation basins where effluent from HF area is collected and then reacted with Lime (CaCO3) to reduce fluoride content below 10ppm
For reduction of oil in effluent water LAB plant have CPI separator installed to separate oil from effluent water The oil separated is send to Slope oil storage
In addition to this there is hydrocarbon pit installed in front end to collect pump and filter drains which is being blended in return kerosene to reduce oil load in effluent systemThere all oil collection pits installed in storm water channels to avoid oil going into the river via gates
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Cooling water systemFor cooling the final products Byproducts to normal ambient temperatures the products byproducts are cooled in coolers The cooling media used is water There are three cooling towers installed in LAB planta) HF cooling tower it is separate cooling tower to avoid HF ingrace in coolers in non-HF
areab) Front End Cooling towerc) Back End cooling tower
Fin Fan coolers The distillation columns overheads are condensed in air-cooled fin fan coolers The advantage of these coolers over water-cooled coolers is low operating cost
Safety measures taken in LAB Plant
1) Safety Interlocks for tripping the operation of equipments in case process variables touches maximum allowable value
2) Flare system for burning excess gases from process3) Infra red detection system for Pacol Reactor and Hot pumps 4) Hydrocarbon detection system for detecting hydrocarbon leakages5) H2S detection system and siren for detecting H2S gas leakages 6) HF Detection system for detecting HF leakages7) Schedule HF leak testing of HF flanges8) Application of HF detection paints to all HF flanges to detect HF leak by decolouration9) Schedule Thickness survey of pipelines in HF area 10) Fire water sprinkler system for HF vessels Columns and pumps11) Fire water sprinkler system for Hot oil pumps12) Yellow boundary marking of HF area where personal protective equipments (PPErsquos) are
mandatory 13) Personal protective equipments (PPErsquos) for HF area Different types of PVC suits are defined
for different types of jobs ( A B C and D type)14) Separate breathing air reciprocating compressor for breathing air for C and D type PVC
suits in case of eemergency15) KOH scrubbing for venting from all HF equipments so that HF will not release into the
flare16) Daily Benzene monitoring with dragger tubes to detect any Benzene leaks from process17) Close draining system of HF and Benzene
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PROJECT ndashI
The project is about developing a ldquoBENZENE-WATER WASHrdquo system to remove the impurities coming with fresh benzene that enters into benzene stripper and effects thefin-fan cooler The project is about developing such a scheme which will remove these impurities before entering the benzene stripper to eliminate the failure of fin-fan cooler
The scheme should also be such that it should not reduce the efficiency of the equipment and should be cost-effective
What is Benzene stripper
The high volatility of water dissolved in hydrocarbons is used in this column to obtain water-free benzene in the column bottoms which also removes any dissolved oxygen or non-condensibles in the benzene or off spec feeds Makeup benzene is fed to the overhead receiver on level control reset by the overhead receiver level controller It is refluxed via the overhead pump on flow control reset by the column bottom level controller and sent to the reaction section by the bottoms pump via the benzene stripper feedbottoms exchanger on flow control which is reset by the benzene column receiver level controller The benzene stripper receiver floats on the flare and is sized big enough to allow enough settling time for the water There is a small nitrogen flow via a conservation vent into the receiver vapor flare to maintain a slight nitrogen purge Water is collected in the boot and drained periodically whenever there is a boot high alarm Maintain a visible benzene water interface in the boot sight glass The benzene at the column bottom normally has a water content of less than 20ppm actually much lower if the column is operated well A moisture analyzer alarm high is provided The heat input to the column is provided by a hot oil reboiler with the hot oil flow controlled Off-spec material from the off-spec tank is normally rerun via the benzene stripper coming into the column receiver
What is the Issue
The benzene stripper column overheads are condensed in air-cooler (fin-fan coolers EC-301)The advantage of using this fin-fan cooler is the low operating cost no space constraint as are not on ground level etc This tube-bundle was failing at a frequency of once in a span of two years Failure analysis study was carried out and found that there are some impurities coming along with fresh benzene which are forming acidic solution after condensing in fin-fan This acidic solution formed was causing the repeated failure of tube-bundle
Water dosing was started upstream of the fin-fan bundle to dissolve out the impurities or to neutralize the acidic solution so that tubes can be saved This practice was started in 2008 Even after this modification the failures and continue and its difficult to analyze that what type of impurities are coming with benzene
22 of 72
So to eliminate this problem a scheme has been plotted to design a benzene scrubbing system This will be basically washing of benzene with DM water to remove the impurities before it enters the benzene stripper
The schematic diagram of this system is shown below
The scheme consists of a static mixture for mixing benzene and water for a particular residence time and at a particular velocity as required A gravity settler is for separating benzene and water on the basis of density difference
23 of 72
STATIC MIXER
This mixing device has no moving parts is simple and its cost can be quite reasonable when compared to mechanical driven mixers Static or motionless mixers are relatively new development and have proven to be effective for many specific and valuable process application It is useful for a wide range of viscosity fluids particularly useful in liquid-liquid mixing and also for some gas-liquid dispersion
The concept of motionless mixers is to achieve a uniform composition and temperature distribution in fluids flowing through the device The concept is build around a stationary rigid element placed in a pipe or cylinder that uses the energy of fluid flowing past to produce the mixing The unit becomes more efficient by adding additional static elements causing the flowing fluid elements to split rearrange recombine and split again to repeat the process lsquoxrsquo times for a uniform or homogeneous flowing stream is produced at discharge
Principle of operation
The static mixer unit is a series of fixed helical elements enclosed within a tubular housing
LIQUID ndash LIQUID SEPARATION(Decanters)
Separation of two liquid phases immiscible or partially miscible liquids is a common requirement in the process industries It is also frequently necessary to separate small quantities of entrained water from process streams The simplest form of equipment used to separate liquid phases is the gravity settling tank the decanter Various proprietary equipment is also used to promote coalescence and improve separation in difficult systems or where emulsions are likely to form Centrifugal separators are also used
Decanters (settlers)
Decanters are used to separate liquids where there is a sufficient difference in density between the liquids for the droplets to settle readily Decanters are essentially tanks which give sufficient residence time for the droplets of the dispersed phase to rise (or settle ) to the interface between the phases and coalesce
In an operating decanter there will be three distinct zones or bands clear heavy liquid separating dispersed liquid (the dispersion zone) and clear light liquid The position of the interface can be controlled with or without the use of instruments by use of a siphon take-off for the heavy liquid
24 of 72
Vertical decanter
The height of the take-off can be determined by making a pressure balance Neglecting friction loss in the pipes the pressure exerted by the combined height of the heavy and light liquid in the vessel must be balanced by the height of the heavy liquid in the take-off leg
(z1-z3)Ρ1g + z3 Ρ2g= z2 Ρ2g
z2 = (z1-z3) Ρ1 + z3 (1)Ρ2
WhereZ1= height from datum to light liquid overflow m Z2=height from datum to heavy liquid overflow m Z3=height from datum to interface m Ρ1=density of the light liquid kgmsup3 Ρ2=density of the heavy liquid kg msup3
The height of the liquid interface should be measured accurately when the liquid densities are close when one component is present only in small quantities or when the throughput is very small A typical scheme for the automatic control of the interface using a level instrument that can detect the position of the interface is shown in the diagram below Where one phase is present only in small amounts it is often recycled to the decanter feed to give more stable operation
25 of 72
CALCULATIONS
STATIC MIXER DESIGN
Required data
1 Physical properties of materials Density kgmsup3
Viscosity Pas = 0001Cp
2 Pressure drop Pressure drop in static mixer is best described by comparison with pipe flow
3 Geometrical parameters Diameter m
Type of static mixer constant (k)
Length (l) m
4 Process variables
Flow rate msup3s TemperaturedegC Pressure bar
26 of 72
Pressure drop calculation
a) Velocity (v)
V = Qπ4 Dsup2
b) Reynoldsrsquos number(Re)
Re= dvρμ
c) Pressure drop (Δp)For Re lt50 Δp =k1x μ x l xQd dsup3
k1= laminar flow constant
For Re gt10sup3 Δp =k2 x ρ x l x vsup2d 2
= k2 x Q x l x 8 x Qsup2d prodsup2 d⁴
k2= turbulent flow constant
Pipe diameter Flow seems to be turbulent as both the materials (B2+ H2O) are not viscous
D =39Q ⁰ ⁴⁵ ρ sup1sup3⁰
Q =52 + 572 = 1092msup3hr = 303 x 10macrsup3msup3s= 38564 ftsup3hr
Ρ = 926328 kgmsup3 =57828 lbftsup3
D =39 x Q ⁰ ⁴⁵ x ρ sup1sup3⁰
D =39 x (38564) ⁰ ⁴⁵ x (57828) sup1sup3⁰ 3600
D= 24 inch = 25 inch = 00635m
27 of 72
Velocity(v)
V =4 Q proddsup2
= 303 x 10macrsup3 msup3s x 4 314 x (00635)sup2
= 0957 ms (approx 1ms)
Reynoldrsquosnumber(Re)
Re = dvρ Μ = 00635 x 1 x 926328 0572
Re =103 x 10⁵
Thus the flow is highly turbulent
Flow regime Reynoldrsquos no(Re)
No of element No of elements to add if viscosity ratio between fluids exceeds 10001
No of elements to add if volumetric ratio between fluids exceeds 1001
Laminar lt1 24 6 61-10 18 6 611-50 14 6 651-100 12 6 6101-500 10 6 6
Transitional 501-1000 8 4 41001-2000 6 4 4
Turbulent 2001-5000 4 2 25001+ 2 2 2
Thus from the above table the mixer will have 2 elements
The mixer length will be based on the number of elements required An approximate length can be determined by multiplying the number of elements by 15
Mixer length = 15 x 2 =3
28 of 72
For turbulent flow applications it is generally recommended that a minimum velocity of 10 ftsec be maintained
V= 0408 x QDsup2 = 0408 x 4813sup2 = 218 ftsec =066 ms
DECANTER DESIGN
Benzene Water
Flow rate (msup3h) 52 572
Flow rate (kgh) 4543812 570311
Density (kgmsup3) 87381 99704
Viscosity (Pas) 0000604 000089
Take Dd = 150microm
microd = (150 Х 10ˉ⁶)sup2 Х 981 Х (87381-99704) 18 Х 000089
microd = -169787 Х 10ˉsup3 ms = -17 mms (rising)
As the flow rate is small we will use a vertical cylindrical vessel
The decanter vessel is sized on the basis that the velocity of the continuous phase must be less than settling velocity of the droplets of the dispersed phase Plug flow is assumed and the velocity of the continuous phase calculated using the area of the interfacemicroc =Lclt microdAiWhere microd = settling velocity of the dispersed phase droplets msmicroc = velocity of the continuous phase msLc = continuous phase volumetric flow rate msup3sAi = area of the interface msup2
29 of 72
Lc = 570311 X 1 99704 3600
= 00015889 msup3s
Ai=Lc = 00015889 microc 00017
= 0935817588 msup2
For a vertical cylindrical decanterAi = prodrsup2
r = 0935817588 prodr = 0545835318 m
Diameter= 1091670637 m
Taking the height as twice the diameter a reasonable value for a cylinder
Height = 2183341274 m
The position of the interface should be such that the band of droplets that collect at the interface waiting to coalesce and cross the interface does not extend to the bottom (or top) of the vessel The depth of the dispersion band is a function of the liquid flow rate and the interfacial area A value of to per cent of the decanter height is usually taken for the design purposes
Take the dispersion band as 10 per cent of the height = 021833mThe residence time of the droplets in the dispersion band = 021833 = 021833microd 00017 =1285926 s (approx 2 min)
This is satisfactory time a time of 2 to 5 min is normally recommended Thus the size of the water (continuous heavy phase) droplets that could be entrained with benzene (light phase) will be
Velocity of benzene phase = 4543812 X 1 X 1 873811 3600093581
=0001543511 ms =1543511mms
30 of 72
So from equation ( ) So the entrained droplet size will be =00015435 X 18 X 0000604 frac12 981 X (99704-873812)
=00001178 m=1178 microm
which is satisfactory below 150 microm
Piping arrangement
To minimize entrainment by the jet of liquid entering the vessel the inlet velocity for a decanter should keep below 1 ms
The velocity from static mixer= 066 ms
Flow rate= 4543812 + 570311 X 1 87381 99704 3600
= 0003033345msup3s
Area of pipe= flow ratevelocity
= 0003033345066
= 0004554572msup2
Pipe diameter =0004554572 x 4prod
= 0076158749 m =29983 inch (approx 3 in)
31 of 72
32 of 72
33 of 72
34 of 72
35 of 72
36 of 72
37 of 72
PROJECT II
CALULATING THE DEW POINT
This project is about the study and evaluation of the performance of the compressors in the Hydrobon section of the LAB plant which is installed to optimize the purity of hydrogen coming from the product separators The compressors in this section include recycle gas compressor and make-up gas compressorThe purity of hydrogen can be increased upto 90
This project will give the company an overall view of this loop The plant is running well about its installed capacity(131-140) The company wants to retain the purity level of nearly 90 for hydrogen even after operating above installed capacity Hence the current project will give the company an idea of the current hydrogen quality(purity) which is obtained and give an idea about changes if any to be made to existing process set-up
HYDROBON REACTOR
Hydrobon reactor is designed to remove contaminants present in the raw kerosene without changing the boiling range The hydrocarbon is passed through a 2 bed reactor feed with S 12 catalyst through a feed effluent exchanger and charge heater which maintain the required reaction temperature(310 c) The reaction required hydrogen gas which is supplied from pacol net gas generated from back end and tattoray hydrogen from PX plantThe reaction charge is heated to the reaction temperature in the charge heater enters the reactor from the top and is distributed over the catalyst bed Catalytic hydrogenation takes place in the reactor The impurities react with hydrogen and form salts which are subsequently separated and finally removed in sour water stripper The reactor effluents after separation is fed to the product stripper to remove lighters and hydrotreated kerosene is fed to molex unit The sulfur and nitrogen levels are reduced to 1 ppm or less
PARAMETERS DESIGN ACTUALPlant load() 100 115Hydrobon feed rate(mthr) 58 60Temperature 416 310Pressure (kgcm2 g) 822 62H2HC ratio 385 460Recycle hydrogen purity(mole)
75 min 95
Hydrobon feed specificationa Bromine
index(mg100gm)800 800
38 of 72
b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
39 of 72
HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
40 of 72
4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
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FLOW DIAGRAM OF HYDROBON SECTION
42 of 72
Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
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nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
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Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
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DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
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ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
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Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
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Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
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Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
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=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
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Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
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Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
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Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
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Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
b) PACOL (Paraffin converted to olefin)
The normal paraffin of carbon range C10 to C13 is converted to linear olefins of carbon range C10 to C13 by Dehydrogenation reaction in UOP Pacol process
The catalyst used in reactor is alumina based platinum catalyst
Platinum catalyst
CH3-C-C-C-CH3 CH3 - C = C ndash C ndash CH3 + H2
N paraffin Linear Mono olefins
There are some side reactions takes places in Pacol they are
CH3 - C = C ndash C ndash CH3 CH3 - C = C = C ndash CH3 + H2
Linear Mono olefins Linear Di olefins
CH3 - C = C = C ndash CH3 Aromatics + H2
Linear Di olefins
As it is dehydrogenation reaction H2 gas is separated from reactor effluent in contact condenser and send to Front End for Hydrobon makeup gas compressor
Cracking also takes place in reactor where ltC10 paraffin and olefins are formed which is removed in distillation column called Pacol stripper The gas separated in stripper is burnt in heater as off gases
The reaction temperature is 470 to 495 DegC while pressure is kept low at 13 kgcm2g
The life of pacol catalyst is about 30 to 40 days As life of the catalyst is low there are two pacol reactors for continuous running of the plant
The conversion of paraffin is about 12 to 13
15 of 72
ContactCondenser
PACOL
STPR
Lighters andOff gases
Pacol reactor
To Alkylation
Charge heater
Normal ParaffinFeed
H2 to front end
DEFINE UNIT
The main purpose of this unit is to increase overall yield of LAB The Diolefins formed in Pacol reaction is converted to Mono olefins and normal paraffin thereby generating more LAB and lesser byproducts
The catalyst used in this reactor is Nickel based on alumina
Nickel catalyst
Diolefins + H2 Mono olefins
Diolefins + H2 Normal Paraffin
The reaction temperature is 180 DegC and pressure is 140 Kgcm2g
Block Diagram of Pacol Unit
16 of 72
IMIXER
2MIXER
HFSTRIPPER
C) ALKYLATION
As described earlier linear olefins (C10 to C13) are alkylated in this unit to form Linear alkyl Benzene (LAB) in presence of HF acid catalyst
The mono olefins are conveterd to Linear alkyl benzene (LAB) while diolefins are conveterd to Heavy alkyl Benzene (HAB) The aromatics are extracted in counter current extraction of HF acid and are separated in distillation column called Acid regenerators
HF acid catalyst
R- CH = CH ndashCH2 ndash Rrsquo + Benzene R-CH-CH2-CH2-Rrsquo
M Olefins
Where R and Rrsquo are alkyl groups (CH3) LAB
R-CH=CH-CH=CH-Rrsquo + 2 Benzene Heavy alkyl benzene
Di olefins HAB
The reaction is instantaneous and carried through a two stage mixer settler system The reactor section effluent is then processed in series of distillation columns where excess Benzene Paraffin LAB and byproduct Heavy alkyl benzene (HAB) gets separated
The separated benzene is recycled back to HF alkylation reactor while separated Paraffin is recycled to Pacol reactor for reaction The product Linear alkyl benzene (LAB) and byproduct Heavy alkyl benzene (HAB) are send to storage
The aromatics and non-normal which are formed in Pacol reaction are extracted in HF reaction unit by counter current extraction of HF acid as POLYMER This polymer is separated in Acid regenerators and then neutralized with KOH and send to storage
Block Diagram of Alkylation process
17 of 72
PROCESS INPUTS amp OUTPUTS
18 of 72
As described earlier plant is divided into two sections
a) Front End for Normal paraffin production from Keroseneb) Back End for Linear alkyl Benzene (LAB) production from N paraffin
The raw material kerosene is supplied to the plant from two sources
a) From Bharat Petroleum Corp Ltd Chembur (BPCL) via 55 Km pipelineb) From Reliance Petroleum Ltd Jamnagar via Shipping
The light kerosene heavy kerosene and Raffinate from front end are combined and send as return kerosene via pipeline or shipping to either BPCL or to RPL Jamnagar
The manufacturing of LAB is done in two grades
a) Domestic grade (Molecular weight 235 to 239)b) Export grade (Molecular weight 239 to 240)
The byproducts of LAB plant are
a) Light Normal paraffinb) Heavy normal paraffinc) Heavy alkyl Benzened) Tar polymer
Installed Capacities
A) For Normal Paraffin 115000 MT Highest prod 126596 MT in year 2001-2002
B) For LAB 100000 MT Highest prod 112484 MT in year 1999-2000
Plant load
A) For Normal Paraffin 117
B) For LAB 120 Production per day
A) For Normal Paraffin 330 MT day (Avrg)
B) For LAB 324 MTday (Avrg)
Customers
19 of 72
1) The Normal paraffin produced in LAB plant is normally used for captive consumption for producing LAB
2) The main customer of LAB is Ms Hindustan Lever and Procter amp Gamble Ltd and their subsidiary
3) The LAB is exported to Europe American African and Asian countries4) The light and Heavy normal paraffin is used to manufacture Chlorinated Paraffin Wax5) Heavy alkyl Benzene is used as lubricants in oil industry
Utility system in LAB plant
Hot oil system
There are two Hot oil Heaters available in LAB plant one for Front End and other is for Back End The Heaters are fired with furnace oil LSHS and off gases from process
The Hot oil (Dow Therm) which is thermic fluid is heated in these Hot oil heaters
The all heat inputs to the column preheater are given by circulating Hot oil at supply temperature of 330 DegC
Effluent System
The effluent generated in LAB plant mainly constitute
a) Fluoride Maximum limit lt 10 ppmb) Oil Maximum limit lt 10 ppm
For reduction of fluoride in effluent water LAB plant have two neutralisation basins where effluent from HF area is collected and then reacted with Lime (CaCO3) to reduce fluoride content below 10ppm
For reduction of oil in effluent water LAB plant have CPI separator installed to separate oil from effluent water The oil separated is send to Slope oil storage
In addition to this there is hydrocarbon pit installed in front end to collect pump and filter drains which is being blended in return kerosene to reduce oil load in effluent systemThere all oil collection pits installed in storm water channels to avoid oil going into the river via gates
20 of 72
Cooling water systemFor cooling the final products Byproducts to normal ambient temperatures the products byproducts are cooled in coolers The cooling media used is water There are three cooling towers installed in LAB planta) HF cooling tower it is separate cooling tower to avoid HF ingrace in coolers in non-HF
areab) Front End Cooling towerc) Back End cooling tower
Fin Fan coolers The distillation columns overheads are condensed in air-cooled fin fan coolers The advantage of these coolers over water-cooled coolers is low operating cost
Safety measures taken in LAB Plant
1) Safety Interlocks for tripping the operation of equipments in case process variables touches maximum allowable value
2) Flare system for burning excess gases from process3) Infra red detection system for Pacol Reactor and Hot pumps 4) Hydrocarbon detection system for detecting hydrocarbon leakages5) H2S detection system and siren for detecting H2S gas leakages 6) HF Detection system for detecting HF leakages7) Schedule HF leak testing of HF flanges8) Application of HF detection paints to all HF flanges to detect HF leak by decolouration9) Schedule Thickness survey of pipelines in HF area 10) Fire water sprinkler system for HF vessels Columns and pumps11) Fire water sprinkler system for Hot oil pumps12) Yellow boundary marking of HF area where personal protective equipments (PPErsquos) are
mandatory 13) Personal protective equipments (PPErsquos) for HF area Different types of PVC suits are defined
for different types of jobs ( A B C and D type)14) Separate breathing air reciprocating compressor for breathing air for C and D type PVC
suits in case of eemergency15) KOH scrubbing for venting from all HF equipments so that HF will not release into the
flare16) Daily Benzene monitoring with dragger tubes to detect any Benzene leaks from process17) Close draining system of HF and Benzene
21 of 72
PROJECT ndashI
The project is about developing a ldquoBENZENE-WATER WASHrdquo system to remove the impurities coming with fresh benzene that enters into benzene stripper and effects thefin-fan cooler The project is about developing such a scheme which will remove these impurities before entering the benzene stripper to eliminate the failure of fin-fan cooler
The scheme should also be such that it should not reduce the efficiency of the equipment and should be cost-effective
What is Benzene stripper
The high volatility of water dissolved in hydrocarbons is used in this column to obtain water-free benzene in the column bottoms which also removes any dissolved oxygen or non-condensibles in the benzene or off spec feeds Makeup benzene is fed to the overhead receiver on level control reset by the overhead receiver level controller It is refluxed via the overhead pump on flow control reset by the column bottom level controller and sent to the reaction section by the bottoms pump via the benzene stripper feedbottoms exchanger on flow control which is reset by the benzene column receiver level controller The benzene stripper receiver floats on the flare and is sized big enough to allow enough settling time for the water There is a small nitrogen flow via a conservation vent into the receiver vapor flare to maintain a slight nitrogen purge Water is collected in the boot and drained periodically whenever there is a boot high alarm Maintain a visible benzene water interface in the boot sight glass The benzene at the column bottom normally has a water content of less than 20ppm actually much lower if the column is operated well A moisture analyzer alarm high is provided The heat input to the column is provided by a hot oil reboiler with the hot oil flow controlled Off-spec material from the off-spec tank is normally rerun via the benzene stripper coming into the column receiver
What is the Issue
The benzene stripper column overheads are condensed in air-cooler (fin-fan coolers EC-301)The advantage of using this fin-fan cooler is the low operating cost no space constraint as are not on ground level etc This tube-bundle was failing at a frequency of once in a span of two years Failure analysis study was carried out and found that there are some impurities coming along with fresh benzene which are forming acidic solution after condensing in fin-fan This acidic solution formed was causing the repeated failure of tube-bundle
Water dosing was started upstream of the fin-fan bundle to dissolve out the impurities or to neutralize the acidic solution so that tubes can be saved This practice was started in 2008 Even after this modification the failures and continue and its difficult to analyze that what type of impurities are coming with benzene
22 of 72
So to eliminate this problem a scheme has been plotted to design a benzene scrubbing system This will be basically washing of benzene with DM water to remove the impurities before it enters the benzene stripper
The schematic diagram of this system is shown below
The scheme consists of a static mixture for mixing benzene and water for a particular residence time and at a particular velocity as required A gravity settler is for separating benzene and water on the basis of density difference
23 of 72
STATIC MIXER
This mixing device has no moving parts is simple and its cost can be quite reasonable when compared to mechanical driven mixers Static or motionless mixers are relatively new development and have proven to be effective for many specific and valuable process application It is useful for a wide range of viscosity fluids particularly useful in liquid-liquid mixing and also for some gas-liquid dispersion
The concept of motionless mixers is to achieve a uniform composition and temperature distribution in fluids flowing through the device The concept is build around a stationary rigid element placed in a pipe or cylinder that uses the energy of fluid flowing past to produce the mixing The unit becomes more efficient by adding additional static elements causing the flowing fluid elements to split rearrange recombine and split again to repeat the process lsquoxrsquo times for a uniform or homogeneous flowing stream is produced at discharge
Principle of operation
The static mixer unit is a series of fixed helical elements enclosed within a tubular housing
LIQUID ndash LIQUID SEPARATION(Decanters)
Separation of two liquid phases immiscible or partially miscible liquids is a common requirement in the process industries It is also frequently necessary to separate small quantities of entrained water from process streams The simplest form of equipment used to separate liquid phases is the gravity settling tank the decanter Various proprietary equipment is also used to promote coalescence and improve separation in difficult systems or where emulsions are likely to form Centrifugal separators are also used
Decanters (settlers)
Decanters are used to separate liquids where there is a sufficient difference in density between the liquids for the droplets to settle readily Decanters are essentially tanks which give sufficient residence time for the droplets of the dispersed phase to rise (or settle ) to the interface between the phases and coalesce
In an operating decanter there will be three distinct zones or bands clear heavy liquid separating dispersed liquid (the dispersion zone) and clear light liquid The position of the interface can be controlled with or without the use of instruments by use of a siphon take-off for the heavy liquid
24 of 72
Vertical decanter
The height of the take-off can be determined by making a pressure balance Neglecting friction loss in the pipes the pressure exerted by the combined height of the heavy and light liquid in the vessel must be balanced by the height of the heavy liquid in the take-off leg
(z1-z3)Ρ1g + z3 Ρ2g= z2 Ρ2g
z2 = (z1-z3) Ρ1 + z3 (1)Ρ2
WhereZ1= height from datum to light liquid overflow m Z2=height from datum to heavy liquid overflow m Z3=height from datum to interface m Ρ1=density of the light liquid kgmsup3 Ρ2=density of the heavy liquid kg msup3
The height of the liquid interface should be measured accurately when the liquid densities are close when one component is present only in small quantities or when the throughput is very small A typical scheme for the automatic control of the interface using a level instrument that can detect the position of the interface is shown in the diagram below Where one phase is present only in small amounts it is often recycled to the decanter feed to give more stable operation
25 of 72
CALCULATIONS
STATIC MIXER DESIGN
Required data
1 Physical properties of materials Density kgmsup3
Viscosity Pas = 0001Cp
2 Pressure drop Pressure drop in static mixer is best described by comparison with pipe flow
3 Geometrical parameters Diameter m
Type of static mixer constant (k)
Length (l) m
4 Process variables
Flow rate msup3s TemperaturedegC Pressure bar
26 of 72
Pressure drop calculation
a) Velocity (v)
V = Qπ4 Dsup2
b) Reynoldsrsquos number(Re)
Re= dvρμ
c) Pressure drop (Δp)For Re lt50 Δp =k1x μ x l xQd dsup3
k1= laminar flow constant
For Re gt10sup3 Δp =k2 x ρ x l x vsup2d 2
= k2 x Q x l x 8 x Qsup2d prodsup2 d⁴
k2= turbulent flow constant
Pipe diameter Flow seems to be turbulent as both the materials (B2+ H2O) are not viscous
D =39Q ⁰ ⁴⁵ ρ sup1sup3⁰
Q =52 + 572 = 1092msup3hr = 303 x 10macrsup3msup3s= 38564 ftsup3hr
Ρ = 926328 kgmsup3 =57828 lbftsup3
D =39 x Q ⁰ ⁴⁵ x ρ sup1sup3⁰
D =39 x (38564) ⁰ ⁴⁵ x (57828) sup1sup3⁰ 3600
D= 24 inch = 25 inch = 00635m
27 of 72
Velocity(v)
V =4 Q proddsup2
= 303 x 10macrsup3 msup3s x 4 314 x (00635)sup2
= 0957 ms (approx 1ms)
Reynoldrsquosnumber(Re)
Re = dvρ Μ = 00635 x 1 x 926328 0572
Re =103 x 10⁵
Thus the flow is highly turbulent
Flow regime Reynoldrsquos no(Re)
No of element No of elements to add if viscosity ratio between fluids exceeds 10001
No of elements to add if volumetric ratio between fluids exceeds 1001
Laminar lt1 24 6 61-10 18 6 611-50 14 6 651-100 12 6 6101-500 10 6 6
Transitional 501-1000 8 4 41001-2000 6 4 4
Turbulent 2001-5000 4 2 25001+ 2 2 2
Thus from the above table the mixer will have 2 elements
The mixer length will be based on the number of elements required An approximate length can be determined by multiplying the number of elements by 15
Mixer length = 15 x 2 =3
28 of 72
For turbulent flow applications it is generally recommended that a minimum velocity of 10 ftsec be maintained
V= 0408 x QDsup2 = 0408 x 4813sup2 = 218 ftsec =066 ms
DECANTER DESIGN
Benzene Water
Flow rate (msup3h) 52 572
Flow rate (kgh) 4543812 570311
Density (kgmsup3) 87381 99704
Viscosity (Pas) 0000604 000089
Take Dd = 150microm
microd = (150 Х 10ˉ⁶)sup2 Х 981 Х (87381-99704) 18 Х 000089
microd = -169787 Х 10ˉsup3 ms = -17 mms (rising)
As the flow rate is small we will use a vertical cylindrical vessel
The decanter vessel is sized on the basis that the velocity of the continuous phase must be less than settling velocity of the droplets of the dispersed phase Plug flow is assumed and the velocity of the continuous phase calculated using the area of the interfacemicroc =Lclt microdAiWhere microd = settling velocity of the dispersed phase droplets msmicroc = velocity of the continuous phase msLc = continuous phase volumetric flow rate msup3sAi = area of the interface msup2
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Lc = 570311 X 1 99704 3600
= 00015889 msup3s
Ai=Lc = 00015889 microc 00017
= 0935817588 msup2
For a vertical cylindrical decanterAi = prodrsup2
r = 0935817588 prodr = 0545835318 m
Diameter= 1091670637 m
Taking the height as twice the diameter a reasonable value for a cylinder
Height = 2183341274 m
The position of the interface should be such that the band of droplets that collect at the interface waiting to coalesce and cross the interface does not extend to the bottom (or top) of the vessel The depth of the dispersion band is a function of the liquid flow rate and the interfacial area A value of to per cent of the decanter height is usually taken for the design purposes
Take the dispersion band as 10 per cent of the height = 021833mThe residence time of the droplets in the dispersion band = 021833 = 021833microd 00017 =1285926 s (approx 2 min)
This is satisfactory time a time of 2 to 5 min is normally recommended Thus the size of the water (continuous heavy phase) droplets that could be entrained with benzene (light phase) will be
Velocity of benzene phase = 4543812 X 1 X 1 873811 3600093581
=0001543511 ms =1543511mms
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So from equation ( ) So the entrained droplet size will be =00015435 X 18 X 0000604 frac12 981 X (99704-873812)
=00001178 m=1178 microm
which is satisfactory below 150 microm
Piping arrangement
To minimize entrainment by the jet of liquid entering the vessel the inlet velocity for a decanter should keep below 1 ms
The velocity from static mixer= 066 ms
Flow rate= 4543812 + 570311 X 1 87381 99704 3600
= 0003033345msup3s
Area of pipe= flow ratevelocity
= 0003033345066
= 0004554572msup2
Pipe diameter =0004554572 x 4prod
= 0076158749 m =29983 inch (approx 3 in)
31 of 72
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37 of 72
PROJECT II
CALULATING THE DEW POINT
This project is about the study and evaluation of the performance of the compressors in the Hydrobon section of the LAB plant which is installed to optimize the purity of hydrogen coming from the product separators The compressors in this section include recycle gas compressor and make-up gas compressorThe purity of hydrogen can be increased upto 90
This project will give the company an overall view of this loop The plant is running well about its installed capacity(131-140) The company wants to retain the purity level of nearly 90 for hydrogen even after operating above installed capacity Hence the current project will give the company an idea of the current hydrogen quality(purity) which is obtained and give an idea about changes if any to be made to existing process set-up
HYDROBON REACTOR
Hydrobon reactor is designed to remove contaminants present in the raw kerosene without changing the boiling range The hydrocarbon is passed through a 2 bed reactor feed with S 12 catalyst through a feed effluent exchanger and charge heater which maintain the required reaction temperature(310 c) The reaction required hydrogen gas which is supplied from pacol net gas generated from back end and tattoray hydrogen from PX plantThe reaction charge is heated to the reaction temperature in the charge heater enters the reactor from the top and is distributed over the catalyst bed Catalytic hydrogenation takes place in the reactor The impurities react with hydrogen and form salts which are subsequently separated and finally removed in sour water stripper The reactor effluents after separation is fed to the product stripper to remove lighters and hydrotreated kerosene is fed to molex unit The sulfur and nitrogen levels are reduced to 1 ppm or less
PARAMETERS DESIGN ACTUALPlant load() 100 115Hydrobon feed rate(mthr) 58 60Temperature 416 310Pressure (kgcm2 g) 822 62H2HC ratio 385 460Recycle hydrogen purity(mole)
75 min 95
Hydrobon feed specificationa Bromine
index(mg100gm)800 800
38 of 72
b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
39 of 72
HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
40 of 72
4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
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FLOW DIAGRAM OF HYDROBON SECTION
42 of 72
Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
43 of 72
nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
44 of 72
Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
45 of 72
DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
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ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
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Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
49 of 72
Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
50 of 72
Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
51 of 72
=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
52 of 72
Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
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Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
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Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
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Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
ContactCondenser
PACOL
STPR
Lighters andOff gases
Pacol reactor
To Alkylation
Charge heater
Normal ParaffinFeed
H2 to front end
DEFINE UNIT
The main purpose of this unit is to increase overall yield of LAB The Diolefins formed in Pacol reaction is converted to Mono olefins and normal paraffin thereby generating more LAB and lesser byproducts
The catalyst used in this reactor is Nickel based on alumina
Nickel catalyst
Diolefins + H2 Mono olefins
Diolefins + H2 Normal Paraffin
The reaction temperature is 180 DegC and pressure is 140 Kgcm2g
Block Diagram of Pacol Unit
16 of 72
IMIXER
2MIXER
HFSTRIPPER
C) ALKYLATION
As described earlier linear olefins (C10 to C13) are alkylated in this unit to form Linear alkyl Benzene (LAB) in presence of HF acid catalyst
The mono olefins are conveterd to Linear alkyl benzene (LAB) while diolefins are conveterd to Heavy alkyl Benzene (HAB) The aromatics are extracted in counter current extraction of HF acid and are separated in distillation column called Acid regenerators
HF acid catalyst
R- CH = CH ndashCH2 ndash Rrsquo + Benzene R-CH-CH2-CH2-Rrsquo
M Olefins
Where R and Rrsquo are alkyl groups (CH3) LAB
R-CH=CH-CH=CH-Rrsquo + 2 Benzene Heavy alkyl benzene
Di olefins HAB
The reaction is instantaneous and carried through a two stage mixer settler system The reactor section effluent is then processed in series of distillation columns where excess Benzene Paraffin LAB and byproduct Heavy alkyl benzene (HAB) gets separated
The separated benzene is recycled back to HF alkylation reactor while separated Paraffin is recycled to Pacol reactor for reaction The product Linear alkyl benzene (LAB) and byproduct Heavy alkyl benzene (HAB) are send to storage
The aromatics and non-normal which are formed in Pacol reaction are extracted in HF reaction unit by counter current extraction of HF acid as POLYMER This polymer is separated in Acid regenerators and then neutralized with KOH and send to storage
Block Diagram of Alkylation process
17 of 72
PROCESS INPUTS amp OUTPUTS
18 of 72
As described earlier plant is divided into two sections
a) Front End for Normal paraffin production from Keroseneb) Back End for Linear alkyl Benzene (LAB) production from N paraffin
The raw material kerosene is supplied to the plant from two sources
a) From Bharat Petroleum Corp Ltd Chembur (BPCL) via 55 Km pipelineb) From Reliance Petroleum Ltd Jamnagar via Shipping
The light kerosene heavy kerosene and Raffinate from front end are combined and send as return kerosene via pipeline or shipping to either BPCL or to RPL Jamnagar
The manufacturing of LAB is done in two grades
a) Domestic grade (Molecular weight 235 to 239)b) Export grade (Molecular weight 239 to 240)
The byproducts of LAB plant are
a) Light Normal paraffinb) Heavy normal paraffinc) Heavy alkyl Benzened) Tar polymer
Installed Capacities
A) For Normal Paraffin 115000 MT Highest prod 126596 MT in year 2001-2002
B) For LAB 100000 MT Highest prod 112484 MT in year 1999-2000
Plant load
A) For Normal Paraffin 117
B) For LAB 120 Production per day
A) For Normal Paraffin 330 MT day (Avrg)
B) For LAB 324 MTday (Avrg)
Customers
19 of 72
1) The Normal paraffin produced in LAB plant is normally used for captive consumption for producing LAB
2) The main customer of LAB is Ms Hindustan Lever and Procter amp Gamble Ltd and their subsidiary
3) The LAB is exported to Europe American African and Asian countries4) The light and Heavy normal paraffin is used to manufacture Chlorinated Paraffin Wax5) Heavy alkyl Benzene is used as lubricants in oil industry
Utility system in LAB plant
Hot oil system
There are two Hot oil Heaters available in LAB plant one for Front End and other is for Back End The Heaters are fired with furnace oil LSHS and off gases from process
The Hot oil (Dow Therm) which is thermic fluid is heated in these Hot oil heaters
The all heat inputs to the column preheater are given by circulating Hot oil at supply temperature of 330 DegC
Effluent System
The effluent generated in LAB plant mainly constitute
a) Fluoride Maximum limit lt 10 ppmb) Oil Maximum limit lt 10 ppm
For reduction of fluoride in effluent water LAB plant have two neutralisation basins where effluent from HF area is collected and then reacted with Lime (CaCO3) to reduce fluoride content below 10ppm
For reduction of oil in effluent water LAB plant have CPI separator installed to separate oil from effluent water The oil separated is send to Slope oil storage
In addition to this there is hydrocarbon pit installed in front end to collect pump and filter drains which is being blended in return kerosene to reduce oil load in effluent systemThere all oil collection pits installed in storm water channels to avoid oil going into the river via gates
20 of 72
Cooling water systemFor cooling the final products Byproducts to normal ambient temperatures the products byproducts are cooled in coolers The cooling media used is water There are three cooling towers installed in LAB planta) HF cooling tower it is separate cooling tower to avoid HF ingrace in coolers in non-HF
areab) Front End Cooling towerc) Back End cooling tower
Fin Fan coolers The distillation columns overheads are condensed in air-cooled fin fan coolers The advantage of these coolers over water-cooled coolers is low operating cost
Safety measures taken in LAB Plant
1) Safety Interlocks for tripping the operation of equipments in case process variables touches maximum allowable value
2) Flare system for burning excess gases from process3) Infra red detection system for Pacol Reactor and Hot pumps 4) Hydrocarbon detection system for detecting hydrocarbon leakages5) H2S detection system and siren for detecting H2S gas leakages 6) HF Detection system for detecting HF leakages7) Schedule HF leak testing of HF flanges8) Application of HF detection paints to all HF flanges to detect HF leak by decolouration9) Schedule Thickness survey of pipelines in HF area 10) Fire water sprinkler system for HF vessels Columns and pumps11) Fire water sprinkler system for Hot oil pumps12) Yellow boundary marking of HF area where personal protective equipments (PPErsquos) are
mandatory 13) Personal protective equipments (PPErsquos) for HF area Different types of PVC suits are defined
for different types of jobs ( A B C and D type)14) Separate breathing air reciprocating compressor for breathing air for C and D type PVC
suits in case of eemergency15) KOH scrubbing for venting from all HF equipments so that HF will not release into the
flare16) Daily Benzene monitoring with dragger tubes to detect any Benzene leaks from process17) Close draining system of HF and Benzene
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PROJECT ndashI
The project is about developing a ldquoBENZENE-WATER WASHrdquo system to remove the impurities coming with fresh benzene that enters into benzene stripper and effects thefin-fan cooler The project is about developing such a scheme which will remove these impurities before entering the benzene stripper to eliminate the failure of fin-fan cooler
The scheme should also be such that it should not reduce the efficiency of the equipment and should be cost-effective
What is Benzene stripper
The high volatility of water dissolved in hydrocarbons is used in this column to obtain water-free benzene in the column bottoms which also removes any dissolved oxygen or non-condensibles in the benzene or off spec feeds Makeup benzene is fed to the overhead receiver on level control reset by the overhead receiver level controller It is refluxed via the overhead pump on flow control reset by the column bottom level controller and sent to the reaction section by the bottoms pump via the benzene stripper feedbottoms exchanger on flow control which is reset by the benzene column receiver level controller The benzene stripper receiver floats on the flare and is sized big enough to allow enough settling time for the water There is a small nitrogen flow via a conservation vent into the receiver vapor flare to maintain a slight nitrogen purge Water is collected in the boot and drained periodically whenever there is a boot high alarm Maintain a visible benzene water interface in the boot sight glass The benzene at the column bottom normally has a water content of less than 20ppm actually much lower if the column is operated well A moisture analyzer alarm high is provided The heat input to the column is provided by a hot oil reboiler with the hot oil flow controlled Off-spec material from the off-spec tank is normally rerun via the benzene stripper coming into the column receiver
What is the Issue
The benzene stripper column overheads are condensed in air-cooler (fin-fan coolers EC-301)The advantage of using this fin-fan cooler is the low operating cost no space constraint as are not on ground level etc This tube-bundle was failing at a frequency of once in a span of two years Failure analysis study was carried out and found that there are some impurities coming along with fresh benzene which are forming acidic solution after condensing in fin-fan This acidic solution formed was causing the repeated failure of tube-bundle
Water dosing was started upstream of the fin-fan bundle to dissolve out the impurities or to neutralize the acidic solution so that tubes can be saved This practice was started in 2008 Even after this modification the failures and continue and its difficult to analyze that what type of impurities are coming with benzene
22 of 72
So to eliminate this problem a scheme has been plotted to design a benzene scrubbing system This will be basically washing of benzene with DM water to remove the impurities before it enters the benzene stripper
The schematic diagram of this system is shown below
The scheme consists of a static mixture for mixing benzene and water for a particular residence time and at a particular velocity as required A gravity settler is for separating benzene and water on the basis of density difference
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STATIC MIXER
This mixing device has no moving parts is simple and its cost can be quite reasonable when compared to mechanical driven mixers Static or motionless mixers are relatively new development and have proven to be effective for many specific and valuable process application It is useful for a wide range of viscosity fluids particularly useful in liquid-liquid mixing and also for some gas-liquid dispersion
The concept of motionless mixers is to achieve a uniform composition and temperature distribution in fluids flowing through the device The concept is build around a stationary rigid element placed in a pipe or cylinder that uses the energy of fluid flowing past to produce the mixing The unit becomes more efficient by adding additional static elements causing the flowing fluid elements to split rearrange recombine and split again to repeat the process lsquoxrsquo times for a uniform or homogeneous flowing stream is produced at discharge
Principle of operation
The static mixer unit is a series of fixed helical elements enclosed within a tubular housing
LIQUID ndash LIQUID SEPARATION(Decanters)
Separation of two liquid phases immiscible or partially miscible liquids is a common requirement in the process industries It is also frequently necessary to separate small quantities of entrained water from process streams The simplest form of equipment used to separate liquid phases is the gravity settling tank the decanter Various proprietary equipment is also used to promote coalescence and improve separation in difficult systems or where emulsions are likely to form Centrifugal separators are also used
Decanters (settlers)
Decanters are used to separate liquids where there is a sufficient difference in density between the liquids for the droplets to settle readily Decanters are essentially tanks which give sufficient residence time for the droplets of the dispersed phase to rise (or settle ) to the interface between the phases and coalesce
In an operating decanter there will be three distinct zones or bands clear heavy liquid separating dispersed liquid (the dispersion zone) and clear light liquid The position of the interface can be controlled with or without the use of instruments by use of a siphon take-off for the heavy liquid
24 of 72
Vertical decanter
The height of the take-off can be determined by making a pressure balance Neglecting friction loss in the pipes the pressure exerted by the combined height of the heavy and light liquid in the vessel must be balanced by the height of the heavy liquid in the take-off leg
(z1-z3)Ρ1g + z3 Ρ2g= z2 Ρ2g
z2 = (z1-z3) Ρ1 + z3 (1)Ρ2
WhereZ1= height from datum to light liquid overflow m Z2=height from datum to heavy liquid overflow m Z3=height from datum to interface m Ρ1=density of the light liquid kgmsup3 Ρ2=density of the heavy liquid kg msup3
The height of the liquid interface should be measured accurately when the liquid densities are close when one component is present only in small quantities or when the throughput is very small A typical scheme for the automatic control of the interface using a level instrument that can detect the position of the interface is shown in the diagram below Where one phase is present only in small amounts it is often recycled to the decanter feed to give more stable operation
25 of 72
CALCULATIONS
STATIC MIXER DESIGN
Required data
1 Physical properties of materials Density kgmsup3
Viscosity Pas = 0001Cp
2 Pressure drop Pressure drop in static mixer is best described by comparison with pipe flow
3 Geometrical parameters Diameter m
Type of static mixer constant (k)
Length (l) m
4 Process variables
Flow rate msup3s TemperaturedegC Pressure bar
26 of 72
Pressure drop calculation
a) Velocity (v)
V = Qπ4 Dsup2
b) Reynoldsrsquos number(Re)
Re= dvρμ
c) Pressure drop (Δp)For Re lt50 Δp =k1x μ x l xQd dsup3
k1= laminar flow constant
For Re gt10sup3 Δp =k2 x ρ x l x vsup2d 2
= k2 x Q x l x 8 x Qsup2d prodsup2 d⁴
k2= turbulent flow constant
Pipe diameter Flow seems to be turbulent as both the materials (B2+ H2O) are not viscous
D =39Q ⁰ ⁴⁵ ρ sup1sup3⁰
Q =52 + 572 = 1092msup3hr = 303 x 10macrsup3msup3s= 38564 ftsup3hr
Ρ = 926328 kgmsup3 =57828 lbftsup3
D =39 x Q ⁰ ⁴⁵ x ρ sup1sup3⁰
D =39 x (38564) ⁰ ⁴⁵ x (57828) sup1sup3⁰ 3600
D= 24 inch = 25 inch = 00635m
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Velocity(v)
V =4 Q proddsup2
= 303 x 10macrsup3 msup3s x 4 314 x (00635)sup2
= 0957 ms (approx 1ms)
Reynoldrsquosnumber(Re)
Re = dvρ Μ = 00635 x 1 x 926328 0572
Re =103 x 10⁵
Thus the flow is highly turbulent
Flow regime Reynoldrsquos no(Re)
No of element No of elements to add if viscosity ratio between fluids exceeds 10001
No of elements to add if volumetric ratio between fluids exceeds 1001
Laminar lt1 24 6 61-10 18 6 611-50 14 6 651-100 12 6 6101-500 10 6 6
Transitional 501-1000 8 4 41001-2000 6 4 4
Turbulent 2001-5000 4 2 25001+ 2 2 2
Thus from the above table the mixer will have 2 elements
The mixer length will be based on the number of elements required An approximate length can be determined by multiplying the number of elements by 15
Mixer length = 15 x 2 =3
28 of 72
For turbulent flow applications it is generally recommended that a minimum velocity of 10 ftsec be maintained
V= 0408 x QDsup2 = 0408 x 4813sup2 = 218 ftsec =066 ms
DECANTER DESIGN
Benzene Water
Flow rate (msup3h) 52 572
Flow rate (kgh) 4543812 570311
Density (kgmsup3) 87381 99704
Viscosity (Pas) 0000604 000089
Take Dd = 150microm
microd = (150 Х 10ˉ⁶)sup2 Х 981 Х (87381-99704) 18 Х 000089
microd = -169787 Х 10ˉsup3 ms = -17 mms (rising)
As the flow rate is small we will use a vertical cylindrical vessel
The decanter vessel is sized on the basis that the velocity of the continuous phase must be less than settling velocity of the droplets of the dispersed phase Plug flow is assumed and the velocity of the continuous phase calculated using the area of the interfacemicroc =Lclt microdAiWhere microd = settling velocity of the dispersed phase droplets msmicroc = velocity of the continuous phase msLc = continuous phase volumetric flow rate msup3sAi = area of the interface msup2
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Lc = 570311 X 1 99704 3600
= 00015889 msup3s
Ai=Lc = 00015889 microc 00017
= 0935817588 msup2
For a vertical cylindrical decanterAi = prodrsup2
r = 0935817588 prodr = 0545835318 m
Diameter= 1091670637 m
Taking the height as twice the diameter a reasonable value for a cylinder
Height = 2183341274 m
The position of the interface should be such that the band of droplets that collect at the interface waiting to coalesce and cross the interface does not extend to the bottom (or top) of the vessel The depth of the dispersion band is a function of the liquid flow rate and the interfacial area A value of to per cent of the decanter height is usually taken for the design purposes
Take the dispersion band as 10 per cent of the height = 021833mThe residence time of the droplets in the dispersion band = 021833 = 021833microd 00017 =1285926 s (approx 2 min)
This is satisfactory time a time of 2 to 5 min is normally recommended Thus the size of the water (continuous heavy phase) droplets that could be entrained with benzene (light phase) will be
Velocity of benzene phase = 4543812 X 1 X 1 873811 3600093581
=0001543511 ms =1543511mms
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So from equation ( ) So the entrained droplet size will be =00015435 X 18 X 0000604 frac12 981 X (99704-873812)
=00001178 m=1178 microm
which is satisfactory below 150 microm
Piping arrangement
To minimize entrainment by the jet of liquid entering the vessel the inlet velocity for a decanter should keep below 1 ms
The velocity from static mixer= 066 ms
Flow rate= 4543812 + 570311 X 1 87381 99704 3600
= 0003033345msup3s
Area of pipe= flow ratevelocity
= 0003033345066
= 0004554572msup2
Pipe diameter =0004554572 x 4prod
= 0076158749 m =29983 inch (approx 3 in)
31 of 72
32 of 72
33 of 72
34 of 72
35 of 72
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PROJECT II
CALULATING THE DEW POINT
This project is about the study and evaluation of the performance of the compressors in the Hydrobon section of the LAB plant which is installed to optimize the purity of hydrogen coming from the product separators The compressors in this section include recycle gas compressor and make-up gas compressorThe purity of hydrogen can be increased upto 90
This project will give the company an overall view of this loop The plant is running well about its installed capacity(131-140) The company wants to retain the purity level of nearly 90 for hydrogen even after operating above installed capacity Hence the current project will give the company an idea of the current hydrogen quality(purity) which is obtained and give an idea about changes if any to be made to existing process set-up
HYDROBON REACTOR
Hydrobon reactor is designed to remove contaminants present in the raw kerosene without changing the boiling range The hydrocarbon is passed through a 2 bed reactor feed with S 12 catalyst through a feed effluent exchanger and charge heater which maintain the required reaction temperature(310 c) The reaction required hydrogen gas which is supplied from pacol net gas generated from back end and tattoray hydrogen from PX plantThe reaction charge is heated to the reaction temperature in the charge heater enters the reactor from the top and is distributed over the catalyst bed Catalytic hydrogenation takes place in the reactor The impurities react with hydrogen and form salts which are subsequently separated and finally removed in sour water stripper The reactor effluents after separation is fed to the product stripper to remove lighters and hydrotreated kerosene is fed to molex unit The sulfur and nitrogen levels are reduced to 1 ppm or less
PARAMETERS DESIGN ACTUALPlant load() 100 115Hydrobon feed rate(mthr) 58 60Temperature 416 310Pressure (kgcm2 g) 822 62H2HC ratio 385 460Recycle hydrogen purity(mole)
75 min 95
Hydrobon feed specificationa Bromine
index(mg100gm)800 800
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b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
39 of 72
HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
40 of 72
4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
41 of 72
FLOW DIAGRAM OF HYDROBON SECTION
42 of 72
Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
43 of 72
nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
44 of 72
Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
45 of 72
DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
46 of 72
DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
47 of 72
ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
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Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
49 of 72
Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
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Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
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=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
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Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
53 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
54 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
55 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
IMIXER
2MIXER
HFSTRIPPER
C) ALKYLATION
As described earlier linear olefins (C10 to C13) are alkylated in this unit to form Linear alkyl Benzene (LAB) in presence of HF acid catalyst
The mono olefins are conveterd to Linear alkyl benzene (LAB) while diolefins are conveterd to Heavy alkyl Benzene (HAB) The aromatics are extracted in counter current extraction of HF acid and are separated in distillation column called Acid regenerators
HF acid catalyst
R- CH = CH ndashCH2 ndash Rrsquo + Benzene R-CH-CH2-CH2-Rrsquo
M Olefins
Where R and Rrsquo are alkyl groups (CH3) LAB
R-CH=CH-CH=CH-Rrsquo + 2 Benzene Heavy alkyl benzene
Di olefins HAB
The reaction is instantaneous and carried through a two stage mixer settler system The reactor section effluent is then processed in series of distillation columns where excess Benzene Paraffin LAB and byproduct Heavy alkyl benzene (HAB) gets separated
The separated benzene is recycled back to HF alkylation reactor while separated Paraffin is recycled to Pacol reactor for reaction The product Linear alkyl benzene (LAB) and byproduct Heavy alkyl benzene (HAB) are send to storage
The aromatics and non-normal which are formed in Pacol reaction are extracted in HF reaction unit by counter current extraction of HF acid as POLYMER This polymer is separated in Acid regenerators and then neutralized with KOH and send to storage
Block Diagram of Alkylation process
17 of 72
PROCESS INPUTS amp OUTPUTS
18 of 72
As described earlier plant is divided into two sections
a) Front End for Normal paraffin production from Keroseneb) Back End for Linear alkyl Benzene (LAB) production from N paraffin
The raw material kerosene is supplied to the plant from two sources
a) From Bharat Petroleum Corp Ltd Chembur (BPCL) via 55 Km pipelineb) From Reliance Petroleum Ltd Jamnagar via Shipping
The light kerosene heavy kerosene and Raffinate from front end are combined and send as return kerosene via pipeline or shipping to either BPCL or to RPL Jamnagar
The manufacturing of LAB is done in two grades
a) Domestic grade (Molecular weight 235 to 239)b) Export grade (Molecular weight 239 to 240)
The byproducts of LAB plant are
a) Light Normal paraffinb) Heavy normal paraffinc) Heavy alkyl Benzened) Tar polymer
Installed Capacities
A) For Normal Paraffin 115000 MT Highest prod 126596 MT in year 2001-2002
B) For LAB 100000 MT Highest prod 112484 MT in year 1999-2000
Plant load
A) For Normal Paraffin 117
B) For LAB 120 Production per day
A) For Normal Paraffin 330 MT day (Avrg)
B) For LAB 324 MTday (Avrg)
Customers
19 of 72
1) The Normal paraffin produced in LAB plant is normally used for captive consumption for producing LAB
2) The main customer of LAB is Ms Hindustan Lever and Procter amp Gamble Ltd and their subsidiary
3) The LAB is exported to Europe American African and Asian countries4) The light and Heavy normal paraffin is used to manufacture Chlorinated Paraffin Wax5) Heavy alkyl Benzene is used as lubricants in oil industry
Utility system in LAB plant
Hot oil system
There are two Hot oil Heaters available in LAB plant one for Front End and other is for Back End The Heaters are fired with furnace oil LSHS and off gases from process
The Hot oil (Dow Therm) which is thermic fluid is heated in these Hot oil heaters
The all heat inputs to the column preheater are given by circulating Hot oil at supply temperature of 330 DegC
Effluent System
The effluent generated in LAB plant mainly constitute
a) Fluoride Maximum limit lt 10 ppmb) Oil Maximum limit lt 10 ppm
For reduction of fluoride in effluent water LAB plant have two neutralisation basins where effluent from HF area is collected and then reacted with Lime (CaCO3) to reduce fluoride content below 10ppm
For reduction of oil in effluent water LAB plant have CPI separator installed to separate oil from effluent water The oil separated is send to Slope oil storage
In addition to this there is hydrocarbon pit installed in front end to collect pump and filter drains which is being blended in return kerosene to reduce oil load in effluent systemThere all oil collection pits installed in storm water channels to avoid oil going into the river via gates
20 of 72
Cooling water systemFor cooling the final products Byproducts to normal ambient temperatures the products byproducts are cooled in coolers The cooling media used is water There are three cooling towers installed in LAB planta) HF cooling tower it is separate cooling tower to avoid HF ingrace in coolers in non-HF
areab) Front End Cooling towerc) Back End cooling tower
Fin Fan coolers The distillation columns overheads are condensed in air-cooled fin fan coolers The advantage of these coolers over water-cooled coolers is low operating cost
Safety measures taken in LAB Plant
1) Safety Interlocks for tripping the operation of equipments in case process variables touches maximum allowable value
2) Flare system for burning excess gases from process3) Infra red detection system for Pacol Reactor and Hot pumps 4) Hydrocarbon detection system for detecting hydrocarbon leakages5) H2S detection system and siren for detecting H2S gas leakages 6) HF Detection system for detecting HF leakages7) Schedule HF leak testing of HF flanges8) Application of HF detection paints to all HF flanges to detect HF leak by decolouration9) Schedule Thickness survey of pipelines in HF area 10) Fire water sprinkler system for HF vessels Columns and pumps11) Fire water sprinkler system for Hot oil pumps12) Yellow boundary marking of HF area where personal protective equipments (PPErsquos) are
mandatory 13) Personal protective equipments (PPErsquos) for HF area Different types of PVC suits are defined
for different types of jobs ( A B C and D type)14) Separate breathing air reciprocating compressor for breathing air for C and D type PVC
suits in case of eemergency15) KOH scrubbing for venting from all HF equipments so that HF will not release into the
flare16) Daily Benzene monitoring with dragger tubes to detect any Benzene leaks from process17) Close draining system of HF and Benzene
21 of 72
PROJECT ndashI
The project is about developing a ldquoBENZENE-WATER WASHrdquo system to remove the impurities coming with fresh benzene that enters into benzene stripper and effects thefin-fan cooler The project is about developing such a scheme which will remove these impurities before entering the benzene stripper to eliminate the failure of fin-fan cooler
The scheme should also be such that it should not reduce the efficiency of the equipment and should be cost-effective
What is Benzene stripper
The high volatility of water dissolved in hydrocarbons is used in this column to obtain water-free benzene in the column bottoms which also removes any dissolved oxygen or non-condensibles in the benzene or off spec feeds Makeup benzene is fed to the overhead receiver on level control reset by the overhead receiver level controller It is refluxed via the overhead pump on flow control reset by the column bottom level controller and sent to the reaction section by the bottoms pump via the benzene stripper feedbottoms exchanger on flow control which is reset by the benzene column receiver level controller The benzene stripper receiver floats on the flare and is sized big enough to allow enough settling time for the water There is a small nitrogen flow via a conservation vent into the receiver vapor flare to maintain a slight nitrogen purge Water is collected in the boot and drained periodically whenever there is a boot high alarm Maintain a visible benzene water interface in the boot sight glass The benzene at the column bottom normally has a water content of less than 20ppm actually much lower if the column is operated well A moisture analyzer alarm high is provided The heat input to the column is provided by a hot oil reboiler with the hot oil flow controlled Off-spec material from the off-spec tank is normally rerun via the benzene stripper coming into the column receiver
What is the Issue
The benzene stripper column overheads are condensed in air-cooler (fin-fan coolers EC-301)The advantage of using this fin-fan cooler is the low operating cost no space constraint as are not on ground level etc This tube-bundle was failing at a frequency of once in a span of two years Failure analysis study was carried out and found that there are some impurities coming along with fresh benzene which are forming acidic solution after condensing in fin-fan This acidic solution formed was causing the repeated failure of tube-bundle
Water dosing was started upstream of the fin-fan bundle to dissolve out the impurities or to neutralize the acidic solution so that tubes can be saved This practice was started in 2008 Even after this modification the failures and continue and its difficult to analyze that what type of impurities are coming with benzene
22 of 72
So to eliminate this problem a scheme has been plotted to design a benzene scrubbing system This will be basically washing of benzene with DM water to remove the impurities before it enters the benzene stripper
The schematic diagram of this system is shown below
The scheme consists of a static mixture for mixing benzene and water for a particular residence time and at a particular velocity as required A gravity settler is for separating benzene and water on the basis of density difference
23 of 72
STATIC MIXER
This mixing device has no moving parts is simple and its cost can be quite reasonable when compared to mechanical driven mixers Static or motionless mixers are relatively new development and have proven to be effective for many specific and valuable process application It is useful for a wide range of viscosity fluids particularly useful in liquid-liquid mixing and also for some gas-liquid dispersion
The concept of motionless mixers is to achieve a uniform composition and temperature distribution in fluids flowing through the device The concept is build around a stationary rigid element placed in a pipe or cylinder that uses the energy of fluid flowing past to produce the mixing The unit becomes more efficient by adding additional static elements causing the flowing fluid elements to split rearrange recombine and split again to repeat the process lsquoxrsquo times for a uniform or homogeneous flowing stream is produced at discharge
Principle of operation
The static mixer unit is a series of fixed helical elements enclosed within a tubular housing
LIQUID ndash LIQUID SEPARATION(Decanters)
Separation of two liquid phases immiscible or partially miscible liquids is a common requirement in the process industries It is also frequently necessary to separate small quantities of entrained water from process streams The simplest form of equipment used to separate liquid phases is the gravity settling tank the decanter Various proprietary equipment is also used to promote coalescence and improve separation in difficult systems or where emulsions are likely to form Centrifugal separators are also used
Decanters (settlers)
Decanters are used to separate liquids where there is a sufficient difference in density between the liquids for the droplets to settle readily Decanters are essentially tanks which give sufficient residence time for the droplets of the dispersed phase to rise (or settle ) to the interface between the phases and coalesce
In an operating decanter there will be three distinct zones or bands clear heavy liquid separating dispersed liquid (the dispersion zone) and clear light liquid The position of the interface can be controlled with or without the use of instruments by use of a siphon take-off for the heavy liquid
24 of 72
Vertical decanter
The height of the take-off can be determined by making a pressure balance Neglecting friction loss in the pipes the pressure exerted by the combined height of the heavy and light liquid in the vessel must be balanced by the height of the heavy liquid in the take-off leg
(z1-z3)Ρ1g + z3 Ρ2g= z2 Ρ2g
z2 = (z1-z3) Ρ1 + z3 (1)Ρ2
WhereZ1= height from datum to light liquid overflow m Z2=height from datum to heavy liquid overflow m Z3=height from datum to interface m Ρ1=density of the light liquid kgmsup3 Ρ2=density of the heavy liquid kg msup3
The height of the liquid interface should be measured accurately when the liquid densities are close when one component is present only in small quantities or when the throughput is very small A typical scheme for the automatic control of the interface using a level instrument that can detect the position of the interface is shown in the diagram below Where one phase is present only in small amounts it is often recycled to the decanter feed to give more stable operation
25 of 72
CALCULATIONS
STATIC MIXER DESIGN
Required data
1 Physical properties of materials Density kgmsup3
Viscosity Pas = 0001Cp
2 Pressure drop Pressure drop in static mixer is best described by comparison with pipe flow
3 Geometrical parameters Diameter m
Type of static mixer constant (k)
Length (l) m
4 Process variables
Flow rate msup3s TemperaturedegC Pressure bar
26 of 72
Pressure drop calculation
a) Velocity (v)
V = Qπ4 Dsup2
b) Reynoldsrsquos number(Re)
Re= dvρμ
c) Pressure drop (Δp)For Re lt50 Δp =k1x μ x l xQd dsup3
k1= laminar flow constant
For Re gt10sup3 Δp =k2 x ρ x l x vsup2d 2
= k2 x Q x l x 8 x Qsup2d prodsup2 d⁴
k2= turbulent flow constant
Pipe diameter Flow seems to be turbulent as both the materials (B2+ H2O) are not viscous
D =39Q ⁰ ⁴⁵ ρ sup1sup3⁰
Q =52 + 572 = 1092msup3hr = 303 x 10macrsup3msup3s= 38564 ftsup3hr
Ρ = 926328 kgmsup3 =57828 lbftsup3
D =39 x Q ⁰ ⁴⁵ x ρ sup1sup3⁰
D =39 x (38564) ⁰ ⁴⁵ x (57828) sup1sup3⁰ 3600
D= 24 inch = 25 inch = 00635m
27 of 72
Velocity(v)
V =4 Q proddsup2
= 303 x 10macrsup3 msup3s x 4 314 x (00635)sup2
= 0957 ms (approx 1ms)
Reynoldrsquosnumber(Re)
Re = dvρ Μ = 00635 x 1 x 926328 0572
Re =103 x 10⁵
Thus the flow is highly turbulent
Flow regime Reynoldrsquos no(Re)
No of element No of elements to add if viscosity ratio between fluids exceeds 10001
No of elements to add if volumetric ratio between fluids exceeds 1001
Laminar lt1 24 6 61-10 18 6 611-50 14 6 651-100 12 6 6101-500 10 6 6
Transitional 501-1000 8 4 41001-2000 6 4 4
Turbulent 2001-5000 4 2 25001+ 2 2 2
Thus from the above table the mixer will have 2 elements
The mixer length will be based on the number of elements required An approximate length can be determined by multiplying the number of elements by 15
Mixer length = 15 x 2 =3
28 of 72
For turbulent flow applications it is generally recommended that a minimum velocity of 10 ftsec be maintained
V= 0408 x QDsup2 = 0408 x 4813sup2 = 218 ftsec =066 ms
DECANTER DESIGN
Benzene Water
Flow rate (msup3h) 52 572
Flow rate (kgh) 4543812 570311
Density (kgmsup3) 87381 99704
Viscosity (Pas) 0000604 000089
Take Dd = 150microm
microd = (150 Х 10ˉ⁶)sup2 Х 981 Х (87381-99704) 18 Х 000089
microd = -169787 Х 10ˉsup3 ms = -17 mms (rising)
As the flow rate is small we will use a vertical cylindrical vessel
The decanter vessel is sized on the basis that the velocity of the continuous phase must be less than settling velocity of the droplets of the dispersed phase Plug flow is assumed and the velocity of the continuous phase calculated using the area of the interfacemicroc =Lclt microdAiWhere microd = settling velocity of the dispersed phase droplets msmicroc = velocity of the continuous phase msLc = continuous phase volumetric flow rate msup3sAi = area of the interface msup2
29 of 72
Lc = 570311 X 1 99704 3600
= 00015889 msup3s
Ai=Lc = 00015889 microc 00017
= 0935817588 msup2
For a vertical cylindrical decanterAi = prodrsup2
r = 0935817588 prodr = 0545835318 m
Diameter= 1091670637 m
Taking the height as twice the diameter a reasonable value for a cylinder
Height = 2183341274 m
The position of the interface should be such that the band of droplets that collect at the interface waiting to coalesce and cross the interface does not extend to the bottom (or top) of the vessel The depth of the dispersion band is a function of the liquid flow rate and the interfacial area A value of to per cent of the decanter height is usually taken for the design purposes
Take the dispersion band as 10 per cent of the height = 021833mThe residence time of the droplets in the dispersion band = 021833 = 021833microd 00017 =1285926 s (approx 2 min)
This is satisfactory time a time of 2 to 5 min is normally recommended Thus the size of the water (continuous heavy phase) droplets that could be entrained with benzene (light phase) will be
Velocity of benzene phase = 4543812 X 1 X 1 873811 3600093581
=0001543511 ms =1543511mms
30 of 72
So from equation ( ) So the entrained droplet size will be =00015435 X 18 X 0000604 frac12 981 X (99704-873812)
=00001178 m=1178 microm
which is satisfactory below 150 microm
Piping arrangement
To minimize entrainment by the jet of liquid entering the vessel the inlet velocity for a decanter should keep below 1 ms
The velocity from static mixer= 066 ms
Flow rate= 4543812 + 570311 X 1 87381 99704 3600
= 0003033345msup3s
Area of pipe= flow ratevelocity
= 0003033345066
= 0004554572msup2
Pipe diameter =0004554572 x 4prod
= 0076158749 m =29983 inch (approx 3 in)
31 of 72
32 of 72
33 of 72
34 of 72
35 of 72
36 of 72
37 of 72
PROJECT II
CALULATING THE DEW POINT
This project is about the study and evaluation of the performance of the compressors in the Hydrobon section of the LAB plant which is installed to optimize the purity of hydrogen coming from the product separators The compressors in this section include recycle gas compressor and make-up gas compressorThe purity of hydrogen can be increased upto 90
This project will give the company an overall view of this loop The plant is running well about its installed capacity(131-140) The company wants to retain the purity level of nearly 90 for hydrogen even after operating above installed capacity Hence the current project will give the company an idea of the current hydrogen quality(purity) which is obtained and give an idea about changes if any to be made to existing process set-up
HYDROBON REACTOR
Hydrobon reactor is designed to remove contaminants present in the raw kerosene without changing the boiling range The hydrocarbon is passed through a 2 bed reactor feed with S 12 catalyst through a feed effluent exchanger and charge heater which maintain the required reaction temperature(310 c) The reaction required hydrogen gas which is supplied from pacol net gas generated from back end and tattoray hydrogen from PX plantThe reaction charge is heated to the reaction temperature in the charge heater enters the reactor from the top and is distributed over the catalyst bed Catalytic hydrogenation takes place in the reactor The impurities react with hydrogen and form salts which are subsequently separated and finally removed in sour water stripper The reactor effluents after separation is fed to the product stripper to remove lighters and hydrotreated kerosene is fed to molex unit The sulfur and nitrogen levels are reduced to 1 ppm or less
PARAMETERS DESIGN ACTUALPlant load() 100 115Hydrobon feed rate(mthr) 58 60Temperature 416 310Pressure (kgcm2 g) 822 62H2HC ratio 385 460Recycle hydrogen purity(mole)
75 min 95
Hydrobon feed specificationa Bromine
index(mg100gm)800 800
38 of 72
b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
39 of 72
HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
40 of 72
4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
41 of 72
FLOW DIAGRAM OF HYDROBON SECTION
42 of 72
Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
43 of 72
nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
44 of 72
Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
45 of 72
DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
46 of 72
DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
47 of 72
ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
48 of 72
Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
49 of 72
Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
50 of 72
Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
51 of 72
=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
52 of 72
Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
53 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
54 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
55 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
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FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
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Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
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PROCESS INPUTS amp OUTPUTS
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As described earlier plant is divided into two sections
a) Front End for Normal paraffin production from Keroseneb) Back End for Linear alkyl Benzene (LAB) production from N paraffin
The raw material kerosene is supplied to the plant from two sources
a) From Bharat Petroleum Corp Ltd Chembur (BPCL) via 55 Km pipelineb) From Reliance Petroleum Ltd Jamnagar via Shipping
The light kerosene heavy kerosene and Raffinate from front end are combined and send as return kerosene via pipeline or shipping to either BPCL or to RPL Jamnagar
The manufacturing of LAB is done in two grades
a) Domestic grade (Molecular weight 235 to 239)b) Export grade (Molecular weight 239 to 240)
The byproducts of LAB plant are
a) Light Normal paraffinb) Heavy normal paraffinc) Heavy alkyl Benzened) Tar polymer
Installed Capacities
A) For Normal Paraffin 115000 MT Highest prod 126596 MT in year 2001-2002
B) For LAB 100000 MT Highest prod 112484 MT in year 1999-2000
Plant load
A) For Normal Paraffin 117
B) For LAB 120 Production per day
A) For Normal Paraffin 330 MT day (Avrg)
B) For LAB 324 MTday (Avrg)
Customers
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1) The Normal paraffin produced in LAB plant is normally used for captive consumption for producing LAB
2) The main customer of LAB is Ms Hindustan Lever and Procter amp Gamble Ltd and their subsidiary
3) The LAB is exported to Europe American African and Asian countries4) The light and Heavy normal paraffin is used to manufacture Chlorinated Paraffin Wax5) Heavy alkyl Benzene is used as lubricants in oil industry
Utility system in LAB plant
Hot oil system
There are two Hot oil Heaters available in LAB plant one for Front End and other is for Back End The Heaters are fired with furnace oil LSHS and off gases from process
The Hot oil (Dow Therm) which is thermic fluid is heated in these Hot oil heaters
The all heat inputs to the column preheater are given by circulating Hot oil at supply temperature of 330 DegC
Effluent System
The effluent generated in LAB plant mainly constitute
a) Fluoride Maximum limit lt 10 ppmb) Oil Maximum limit lt 10 ppm
For reduction of fluoride in effluent water LAB plant have two neutralisation basins where effluent from HF area is collected and then reacted with Lime (CaCO3) to reduce fluoride content below 10ppm
For reduction of oil in effluent water LAB plant have CPI separator installed to separate oil from effluent water The oil separated is send to Slope oil storage
In addition to this there is hydrocarbon pit installed in front end to collect pump and filter drains which is being blended in return kerosene to reduce oil load in effluent systemThere all oil collection pits installed in storm water channels to avoid oil going into the river via gates
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Cooling water systemFor cooling the final products Byproducts to normal ambient temperatures the products byproducts are cooled in coolers The cooling media used is water There are three cooling towers installed in LAB planta) HF cooling tower it is separate cooling tower to avoid HF ingrace in coolers in non-HF
areab) Front End Cooling towerc) Back End cooling tower
Fin Fan coolers The distillation columns overheads are condensed in air-cooled fin fan coolers The advantage of these coolers over water-cooled coolers is low operating cost
Safety measures taken in LAB Plant
1) Safety Interlocks for tripping the operation of equipments in case process variables touches maximum allowable value
2) Flare system for burning excess gases from process3) Infra red detection system for Pacol Reactor and Hot pumps 4) Hydrocarbon detection system for detecting hydrocarbon leakages5) H2S detection system and siren for detecting H2S gas leakages 6) HF Detection system for detecting HF leakages7) Schedule HF leak testing of HF flanges8) Application of HF detection paints to all HF flanges to detect HF leak by decolouration9) Schedule Thickness survey of pipelines in HF area 10) Fire water sprinkler system for HF vessels Columns and pumps11) Fire water sprinkler system for Hot oil pumps12) Yellow boundary marking of HF area where personal protective equipments (PPErsquos) are
mandatory 13) Personal protective equipments (PPErsquos) for HF area Different types of PVC suits are defined
for different types of jobs ( A B C and D type)14) Separate breathing air reciprocating compressor for breathing air for C and D type PVC
suits in case of eemergency15) KOH scrubbing for venting from all HF equipments so that HF will not release into the
flare16) Daily Benzene monitoring with dragger tubes to detect any Benzene leaks from process17) Close draining system of HF and Benzene
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PROJECT ndashI
The project is about developing a ldquoBENZENE-WATER WASHrdquo system to remove the impurities coming with fresh benzene that enters into benzene stripper and effects thefin-fan cooler The project is about developing such a scheme which will remove these impurities before entering the benzene stripper to eliminate the failure of fin-fan cooler
The scheme should also be such that it should not reduce the efficiency of the equipment and should be cost-effective
What is Benzene stripper
The high volatility of water dissolved in hydrocarbons is used in this column to obtain water-free benzene in the column bottoms which also removes any dissolved oxygen or non-condensibles in the benzene or off spec feeds Makeup benzene is fed to the overhead receiver on level control reset by the overhead receiver level controller It is refluxed via the overhead pump on flow control reset by the column bottom level controller and sent to the reaction section by the bottoms pump via the benzene stripper feedbottoms exchanger on flow control which is reset by the benzene column receiver level controller The benzene stripper receiver floats on the flare and is sized big enough to allow enough settling time for the water There is a small nitrogen flow via a conservation vent into the receiver vapor flare to maintain a slight nitrogen purge Water is collected in the boot and drained periodically whenever there is a boot high alarm Maintain a visible benzene water interface in the boot sight glass The benzene at the column bottom normally has a water content of less than 20ppm actually much lower if the column is operated well A moisture analyzer alarm high is provided The heat input to the column is provided by a hot oil reboiler with the hot oil flow controlled Off-spec material from the off-spec tank is normally rerun via the benzene stripper coming into the column receiver
What is the Issue
The benzene stripper column overheads are condensed in air-cooler (fin-fan coolers EC-301)The advantage of using this fin-fan cooler is the low operating cost no space constraint as are not on ground level etc This tube-bundle was failing at a frequency of once in a span of two years Failure analysis study was carried out and found that there are some impurities coming along with fresh benzene which are forming acidic solution after condensing in fin-fan This acidic solution formed was causing the repeated failure of tube-bundle
Water dosing was started upstream of the fin-fan bundle to dissolve out the impurities or to neutralize the acidic solution so that tubes can be saved This practice was started in 2008 Even after this modification the failures and continue and its difficult to analyze that what type of impurities are coming with benzene
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So to eliminate this problem a scheme has been plotted to design a benzene scrubbing system This will be basically washing of benzene with DM water to remove the impurities before it enters the benzene stripper
The schematic diagram of this system is shown below
The scheme consists of a static mixture for mixing benzene and water for a particular residence time and at a particular velocity as required A gravity settler is for separating benzene and water on the basis of density difference
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STATIC MIXER
This mixing device has no moving parts is simple and its cost can be quite reasonable when compared to mechanical driven mixers Static or motionless mixers are relatively new development and have proven to be effective for many specific and valuable process application It is useful for a wide range of viscosity fluids particularly useful in liquid-liquid mixing and also for some gas-liquid dispersion
The concept of motionless mixers is to achieve a uniform composition and temperature distribution in fluids flowing through the device The concept is build around a stationary rigid element placed in a pipe or cylinder that uses the energy of fluid flowing past to produce the mixing The unit becomes more efficient by adding additional static elements causing the flowing fluid elements to split rearrange recombine and split again to repeat the process lsquoxrsquo times for a uniform or homogeneous flowing stream is produced at discharge
Principle of operation
The static mixer unit is a series of fixed helical elements enclosed within a tubular housing
LIQUID ndash LIQUID SEPARATION(Decanters)
Separation of two liquid phases immiscible or partially miscible liquids is a common requirement in the process industries It is also frequently necessary to separate small quantities of entrained water from process streams The simplest form of equipment used to separate liquid phases is the gravity settling tank the decanter Various proprietary equipment is also used to promote coalescence and improve separation in difficult systems or where emulsions are likely to form Centrifugal separators are also used
Decanters (settlers)
Decanters are used to separate liquids where there is a sufficient difference in density between the liquids for the droplets to settle readily Decanters are essentially tanks which give sufficient residence time for the droplets of the dispersed phase to rise (or settle ) to the interface between the phases and coalesce
In an operating decanter there will be three distinct zones or bands clear heavy liquid separating dispersed liquid (the dispersion zone) and clear light liquid The position of the interface can be controlled with or without the use of instruments by use of a siphon take-off for the heavy liquid
24 of 72
Vertical decanter
The height of the take-off can be determined by making a pressure balance Neglecting friction loss in the pipes the pressure exerted by the combined height of the heavy and light liquid in the vessel must be balanced by the height of the heavy liquid in the take-off leg
(z1-z3)Ρ1g + z3 Ρ2g= z2 Ρ2g
z2 = (z1-z3) Ρ1 + z3 (1)Ρ2
WhereZ1= height from datum to light liquid overflow m Z2=height from datum to heavy liquid overflow m Z3=height from datum to interface m Ρ1=density of the light liquid kgmsup3 Ρ2=density of the heavy liquid kg msup3
The height of the liquid interface should be measured accurately when the liquid densities are close when one component is present only in small quantities or when the throughput is very small A typical scheme for the automatic control of the interface using a level instrument that can detect the position of the interface is shown in the diagram below Where one phase is present only in small amounts it is often recycled to the decanter feed to give more stable operation
25 of 72
CALCULATIONS
STATIC MIXER DESIGN
Required data
1 Physical properties of materials Density kgmsup3
Viscosity Pas = 0001Cp
2 Pressure drop Pressure drop in static mixer is best described by comparison with pipe flow
3 Geometrical parameters Diameter m
Type of static mixer constant (k)
Length (l) m
4 Process variables
Flow rate msup3s TemperaturedegC Pressure bar
26 of 72
Pressure drop calculation
a) Velocity (v)
V = Qπ4 Dsup2
b) Reynoldsrsquos number(Re)
Re= dvρμ
c) Pressure drop (Δp)For Re lt50 Δp =k1x μ x l xQd dsup3
k1= laminar flow constant
For Re gt10sup3 Δp =k2 x ρ x l x vsup2d 2
= k2 x Q x l x 8 x Qsup2d prodsup2 d⁴
k2= turbulent flow constant
Pipe diameter Flow seems to be turbulent as both the materials (B2+ H2O) are not viscous
D =39Q ⁰ ⁴⁵ ρ sup1sup3⁰
Q =52 + 572 = 1092msup3hr = 303 x 10macrsup3msup3s= 38564 ftsup3hr
Ρ = 926328 kgmsup3 =57828 lbftsup3
D =39 x Q ⁰ ⁴⁵ x ρ sup1sup3⁰
D =39 x (38564) ⁰ ⁴⁵ x (57828) sup1sup3⁰ 3600
D= 24 inch = 25 inch = 00635m
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Velocity(v)
V =4 Q proddsup2
= 303 x 10macrsup3 msup3s x 4 314 x (00635)sup2
= 0957 ms (approx 1ms)
Reynoldrsquosnumber(Re)
Re = dvρ Μ = 00635 x 1 x 926328 0572
Re =103 x 10⁵
Thus the flow is highly turbulent
Flow regime Reynoldrsquos no(Re)
No of element No of elements to add if viscosity ratio between fluids exceeds 10001
No of elements to add if volumetric ratio between fluids exceeds 1001
Laminar lt1 24 6 61-10 18 6 611-50 14 6 651-100 12 6 6101-500 10 6 6
Transitional 501-1000 8 4 41001-2000 6 4 4
Turbulent 2001-5000 4 2 25001+ 2 2 2
Thus from the above table the mixer will have 2 elements
The mixer length will be based on the number of elements required An approximate length can be determined by multiplying the number of elements by 15
Mixer length = 15 x 2 =3
28 of 72
For turbulent flow applications it is generally recommended that a minimum velocity of 10 ftsec be maintained
V= 0408 x QDsup2 = 0408 x 4813sup2 = 218 ftsec =066 ms
DECANTER DESIGN
Benzene Water
Flow rate (msup3h) 52 572
Flow rate (kgh) 4543812 570311
Density (kgmsup3) 87381 99704
Viscosity (Pas) 0000604 000089
Take Dd = 150microm
microd = (150 Х 10ˉ⁶)sup2 Х 981 Х (87381-99704) 18 Х 000089
microd = -169787 Х 10ˉsup3 ms = -17 mms (rising)
As the flow rate is small we will use a vertical cylindrical vessel
The decanter vessel is sized on the basis that the velocity of the continuous phase must be less than settling velocity of the droplets of the dispersed phase Plug flow is assumed and the velocity of the continuous phase calculated using the area of the interfacemicroc =Lclt microdAiWhere microd = settling velocity of the dispersed phase droplets msmicroc = velocity of the continuous phase msLc = continuous phase volumetric flow rate msup3sAi = area of the interface msup2
29 of 72
Lc = 570311 X 1 99704 3600
= 00015889 msup3s
Ai=Lc = 00015889 microc 00017
= 0935817588 msup2
For a vertical cylindrical decanterAi = prodrsup2
r = 0935817588 prodr = 0545835318 m
Diameter= 1091670637 m
Taking the height as twice the diameter a reasonable value for a cylinder
Height = 2183341274 m
The position of the interface should be such that the band of droplets that collect at the interface waiting to coalesce and cross the interface does not extend to the bottom (or top) of the vessel The depth of the dispersion band is a function of the liquid flow rate and the interfacial area A value of to per cent of the decanter height is usually taken for the design purposes
Take the dispersion band as 10 per cent of the height = 021833mThe residence time of the droplets in the dispersion band = 021833 = 021833microd 00017 =1285926 s (approx 2 min)
This is satisfactory time a time of 2 to 5 min is normally recommended Thus the size of the water (continuous heavy phase) droplets that could be entrained with benzene (light phase) will be
Velocity of benzene phase = 4543812 X 1 X 1 873811 3600093581
=0001543511 ms =1543511mms
30 of 72
So from equation ( ) So the entrained droplet size will be =00015435 X 18 X 0000604 frac12 981 X (99704-873812)
=00001178 m=1178 microm
which is satisfactory below 150 microm
Piping arrangement
To minimize entrainment by the jet of liquid entering the vessel the inlet velocity for a decanter should keep below 1 ms
The velocity from static mixer= 066 ms
Flow rate= 4543812 + 570311 X 1 87381 99704 3600
= 0003033345msup3s
Area of pipe= flow ratevelocity
= 0003033345066
= 0004554572msup2
Pipe diameter =0004554572 x 4prod
= 0076158749 m =29983 inch (approx 3 in)
31 of 72
32 of 72
33 of 72
34 of 72
35 of 72
36 of 72
37 of 72
PROJECT II
CALULATING THE DEW POINT
This project is about the study and evaluation of the performance of the compressors in the Hydrobon section of the LAB plant which is installed to optimize the purity of hydrogen coming from the product separators The compressors in this section include recycle gas compressor and make-up gas compressorThe purity of hydrogen can be increased upto 90
This project will give the company an overall view of this loop The plant is running well about its installed capacity(131-140) The company wants to retain the purity level of nearly 90 for hydrogen even after operating above installed capacity Hence the current project will give the company an idea of the current hydrogen quality(purity) which is obtained and give an idea about changes if any to be made to existing process set-up
HYDROBON REACTOR
Hydrobon reactor is designed to remove contaminants present in the raw kerosene without changing the boiling range The hydrocarbon is passed through a 2 bed reactor feed with S 12 catalyst through a feed effluent exchanger and charge heater which maintain the required reaction temperature(310 c) The reaction required hydrogen gas which is supplied from pacol net gas generated from back end and tattoray hydrogen from PX plantThe reaction charge is heated to the reaction temperature in the charge heater enters the reactor from the top and is distributed over the catalyst bed Catalytic hydrogenation takes place in the reactor The impurities react with hydrogen and form salts which are subsequently separated and finally removed in sour water stripper The reactor effluents after separation is fed to the product stripper to remove lighters and hydrotreated kerosene is fed to molex unit The sulfur and nitrogen levels are reduced to 1 ppm or less
PARAMETERS DESIGN ACTUALPlant load() 100 115Hydrobon feed rate(mthr) 58 60Temperature 416 310Pressure (kgcm2 g) 822 62H2HC ratio 385 460Recycle hydrogen purity(mole)
75 min 95
Hydrobon feed specificationa Bromine
index(mg100gm)800 800
38 of 72
b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
39 of 72
HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
40 of 72
4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
41 of 72
FLOW DIAGRAM OF HYDROBON SECTION
42 of 72
Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
43 of 72
nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
44 of 72
Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
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DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
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ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
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Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
49 of 72
Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
50 of 72
Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
51 of 72
=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
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Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
53 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
54 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
55 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
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Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
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Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
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FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
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Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
As described earlier plant is divided into two sections
a) Front End for Normal paraffin production from Keroseneb) Back End for Linear alkyl Benzene (LAB) production from N paraffin
The raw material kerosene is supplied to the plant from two sources
a) From Bharat Petroleum Corp Ltd Chembur (BPCL) via 55 Km pipelineb) From Reliance Petroleum Ltd Jamnagar via Shipping
The light kerosene heavy kerosene and Raffinate from front end are combined and send as return kerosene via pipeline or shipping to either BPCL or to RPL Jamnagar
The manufacturing of LAB is done in two grades
a) Domestic grade (Molecular weight 235 to 239)b) Export grade (Molecular weight 239 to 240)
The byproducts of LAB plant are
a) Light Normal paraffinb) Heavy normal paraffinc) Heavy alkyl Benzened) Tar polymer
Installed Capacities
A) For Normal Paraffin 115000 MT Highest prod 126596 MT in year 2001-2002
B) For LAB 100000 MT Highest prod 112484 MT in year 1999-2000
Plant load
A) For Normal Paraffin 117
B) For LAB 120 Production per day
A) For Normal Paraffin 330 MT day (Avrg)
B) For LAB 324 MTday (Avrg)
Customers
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1) The Normal paraffin produced in LAB plant is normally used for captive consumption for producing LAB
2) The main customer of LAB is Ms Hindustan Lever and Procter amp Gamble Ltd and their subsidiary
3) The LAB is exported to Europe American African and Asian countries4) The light and Heavy normal paraffin is used to manufacture Chlorinated Paraffin Wax5) Heavy alkyl Benzene is used as lubricants in oil industry
Utility system in LAB plant
Hot oil system
There are two Hot oil Heaters available in LAB plant one for Front End and other is for Back End The Heaters are fired with furnace oil LSHS and off gases from process
The Hot oil (Dow Therm) which is thermic fluid is heated in these Hot oil heaters
The all heat inputs to the column preheater are given by circulating Hot oil at supply temperature of 330 DegC
Effluent System
The effluent generated in LAB plant mainly constitute
a) Fluoride Maximum limit lt 10 ppmb) Oil Maximum limit lt 10 ppm
For reduction of fluoride in effluent water LAB plant have two neutralisation basins where effluent from HF area is collected and then reacted with Lime (CaCO3) to reduce fluoride content below 10ppm
For reduction of oil in effluent water LAB plant have CPI separator installed to separate oil from effluent water The oil separated is send to Slope oil storage
In addition to this there is hydrocarbon pit installed in front end to collect pump and filter drains which is being blended in return kerosene to reduce oil load in effluent systemThere all oil collection pits installed in storm water channels to avoid oil going into the river via gates
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Cooling water systemFor cooling the final products Byproducts to normal ambient temperatures the products byproducts are cooled in coolers The cooling media used is water There are three cooling towers installed in LAB planta) HF cooling tower it is separate cooling tower to avoid HF ingrace in coolers in non-HF
areab) Front End Cooling towerc) Back End cooling tower
Fin Fan coolers The distillation columns overheads are condensed in air-cooled fin fan coolers The advantage of these coolers over water-cooled coolers is low operating cost
Safety measures taken in LAB Plant
1) Safety Interlocks for tripping the operation of equipments in case process variables touches maximum allowable value
2) Flare system for burning excess gases from process3) Infra red detection system for Pacol Reactor and Hot pumps 4) Hydrocarbon detection system for detecting hydrocarbon leakages5) H2S detection system and siren for detecting H2S gas leakages 6) HF Detection system for detecting HF leakages7) Schedule HF leak testing of HF flanges8) Application of HF detection paints to all HF flanges to detect HF leak by decolouration9) Schedule Thickness survey of pipelines in HF area 10) Fire water sprinkler system for HF vessels Columns and pumps11) Fire water sprinkler system for Hot oil pumps12) Yellow boundary marking of HF area where personal protective equipments (PPErsquos) are
mandatory 13) Personal protective equipments (PPErsquos) for HF area Different types of PVC suits are defined
for different types of jobs ( A B C and D type)14) Separate breathing air reciprocating compressor for breathing air for C and D type PVC
suits in case of eemergency15) KOH scrubbing for venting from all HF equipments so that HF will not release into the
flare16) Daily Benzene monitoring with dragger tubes to detect any Benzene leaks from process17) Close draining system of HF and Benzene
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PROJECT ndashI
The project is about developing a ldquoBENZENE-WATER WASHrdquo system to remove the impurities coming with fresh benzene that enters into benzene stripper and effects thefin-fan cooler The project is about developing such a scheme which will remove these impurities before entering the benzene stripper to eliminate the failure of fin-fan cooler
The scheme should also be such that it should not reduce the efficiency of the equipment and should be cost-effective
What is Benzene stripper
The high volatility of water dissolved in hydrocarbons is used in this column to obtain water-free benzene in the column bottoms which also removes any dissolved oxygen or non-condensibles in the benzene or off spec feeds Makeup benzene is fed to the overhead receiver on level control reset by the overhead receiver level controller It is refluxed via the overhead pump on flow control reset by the column bottom level controller and sent to the reaction section by the bottoms pump via the benzene stripper feedbottoms exchanger on flow control which is reset by the benzene column receiver level controller The benzene stripper receiver floats on the flare and is sized big enough to allow enough settling time for the water There is a small nitrogen flow via a conservation vent into the receiver vapor flare to maintain a slight nitrogen purge Water is collected in the boot and drained periodically whenever there is a boot high alarm Maintain a visible benzene water interface in the boot sight glass The benzene at the column bottom normally has a water content of less than 20ppm actually much lower if the column is operated well A moisture analyzer alarm high is provided The heat input to the column is provided by a hot oil reboiler with the hot oil flow controlled Off-spec material from the off-spec tank is normally rerun via the benzene stripper coming into the column receiver
What is the Issue
The benzene stripper column overheads are condensed in air-cooler (fin-fan coolers EC-301)The advantage of using this fin-fan cooler is the low operating cost no space constraint as are not on ground level etc This tube-bundle was failing at a frequency of once in a span of two years Failure analysis study was carried out and found that there are some impurities coming along with fresh benzene which are forming acidic solution after condensing in fin-fan This acidic solution formed was causing the repeated failure of tube-bundle
Water dosing was started upstream of the fin-fan bundle to dissolve out the impurities or to neutralize the acidic solution so that tubes can be saved This practice was started in 2008 Even after this modification the failures and continue and its difficult to analyze that what type of impurities are coming with benzene
22 of 72
So to eliminate this problem a scheme has been plotted to design a benzene scrubbing system This will be basically washing of benzene with DM water to remove the impurities before it enters the benzene stripper
The schematic diagram of this system is shown below
The scheme consists of a static mixture for mixing benzene and water for a particular residence time and at a particular velocity as required A gravity settler is for separating benzene and water on the basis of density difference
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STATIC MIXER
This mixing device has no moving parts is simple and its cost can be quite reasonable when compared to mechanical driven mixers Static or motionless mixers are relatively new development and have proven to be effective for many specific and valuable process application It is useful for a wide range of viscosity fluids particularly useful in liquid-liquid mixing and also for some gas-liquid dispersion
The concept of motionless mixers is to achieve a uniform composition and temperature distribution in fluids flowing through the device The concept is build around a stationary rigid element placed in a pipe or cylinder that uses the energy of fluid flowing past to produce the mixing The unit becomes more efficient by adding additional static elements causing the flowing fluid elements to split rearrange recombine and split again to repeat the process lsquoxrsquo times for a uniform or homogeneous flowing stream is produced at discharge
Principle of operation
The static mixer unit is a series of fixed helical elements enclosed within a tubular housing
LIQUID ndash LIQUID SEPARATION(Decanters)
Separation of two liquid phases immiscible or partially miscible liquids is a common requirement in the process industries It is also frequently necessary to separate small quantities of entrained water from process streams The simplest form of equipment used to separate liquid phases is the gravity settling tank the decanter Various proprietary equipment is also used to promote coalescence and improve separation in difficult systems or where emulsions are likely to form Centrifugal separators are also used
Decanters (settlers)
Decanters are used to separate liquids where there is a sufficient difference in density between the liquids for the droplets to settle readily Decanters are essentially tanks which give sufficient residence time for the droplets of the dispersed phase to rise (or settle ) to the interface between the phases and coalesce
In an operating decanter there will be three distinct zones or bands clear heavy liquid separating dispersed liquid (the dispersion zone) and clear light liquid The position of the interface can be controlled with or without the use of instruments by use of a siphon take-off for the heavy liquid
24 of 72
Vertical decanter
The height of the take-off can be determined by making a pressure balance Neglecting friction loss in the pipes the pressure exerted by the combined height of the heavy and light liquid in the vessel must be balanced by the height of the heavy liquid in the take-off leg
(z1-z3)Ρ1g + z3 Ρ2g= z2 Ρ2g
z2 = (z1-z3) Ρ1 + z3 (1)Ρ2
WhereZ1= height from datum to light liquid overflow m Z2=height from datum to heavy liquid overflow m Z3=height from datum to interface m Ρ1=density of the light liquid kgmsup3 Ρ2=density of the heavy liquid kg msup3
The height of the liquid interface should be measured accurately when the liquid densities are close when one component is present only in small quantities or when the throughput is very small A typical scheme for the automatic control of the interface using a level instrument that can detect the position of the interface is shown in the diagram below Where one phase is present only in small amounts it is often recycled to the decanter feed to give more stable operation
25 of 72
CALCULATIONS
STATIC MIXER DESIGN
Required data
1 Physical properties of materials Density kgmsup3
Viscosity Pas = 0001Cp
2 Pressure drop Pressure drop in static mixer is best described by comparison with pipe flow
3 Geometrical parameters Diameter m
Type of static mixer constant (k)
Length (l) m
4 Process variables
Flow rate msup3s TemperaturedegC Pressure bar
26 of 72
Pressure drop calculation
a) Velocity (v)
V = Qπ4 Dsup2
b) Reynoldsrsquos number(Re)
Re= dvρμ
c) Pressure drop (Δp)For Re lt50 Δp =k1x μ x l xQd dsup3
k1= laminar flow constant
For Re gt10sup3 Δp =k2 x ρ x l x vsup2d 2
= k2 x Q x l x 8 x Qsup2d prodsup2 d⁴
k2= turbulent flow constant
Pipe diameter Flow seems to be turbulent as both the materials (B2+ H2O) are not viscous
D =39Q ⁰ ⁴⁵ ρ sup1sup3⁰
Q =52 + 572 = 1092msup3hr = 303 x 10macrsup3msup3s= 38564 ftsup3hr
Ρ = 926328 kgmsup3 =57828 lbftsup3
D =39 x Q ⁰ ⁴⁵ x ρ sup1sup3⁰
D =39 x (38564) ⁰ ⁴⁵ x (57828) sup1sup3⁰ 3600
D= 24 inch = 25 inch = 00635m
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Velocity(v)
V =4 Q proddsup2
= 303 x 10macrsup3 msup3s x 4 314 x (00635)sup2
= 0957 ms (approx 1ms)
Reynoldrsquosnumber(Re)
Re = dvρ Μ = 00635 x 1 x 926328 0572
Re =103 x 10⁵
Thus the flow is highly turbulent
Flow regime Reynoldrsquos no(Re)
No of element No of elements to add if viscosity ratio between fluids exceeds 10001
No of elements to add if volumetric ratio between fluids exceeds 1001
Laminar lt1 24 6 61-10 18 6 611-50 14 6 651-100 12 6 6101-500 10 6 6
Transitional 501-1000 8 4 41001-2000 6 4 4
Turbulent 2001-5000 4 2 25001+ 2 2 2
Thus from the above table the mixer will have 2 elements
The mixer length will be based on the number of elements required An approximate length can be determined by multiplying the number of elements by 15
Mixer length = 15 x 2 =3
28 of 72
For turbulent flow applications it is generally recommended that a minimum velocity of 10 ftsec be maintained
V= 0408 x QDsup2 = 0408 x 4813sup2 = 218 ftsec =066 ms
DECANTER DESIGN
Benzene Water
Flow rate (msup3h) 52 572
Flow rate (kgh) 4543812 570311
Density (kgmsup3) 87381 99704
Viscosity (Pas) 0000604 000089
Take Dd = 150microm
microd = (150 Х 10ˉ⁶)sup2 Х 981 Х (87381-99704) 18 Х 000089
microd = -169787 Х 10ˉsup3 ms = -17 mms (rising)
As the flow rate is small we will use a vertical cylindrical vessel
The decanter vessel is sized on the basis that the velocity of the continuous phase must be less than settling velocity of the droplets of the dispersed phase Plug flow is assumed and the velocity of the continuous phase calculated using the area of the interfacemicroc =Lclt microdAiWhere microd = settling velocity of the dispersed phase droplets msmicroc = velocity of the continuous phase msLc = continuous phase volumetric flow rate msup3sAi = area of the interface msup2
29 of 72
Lc = 570311 X 1 99704 3600
= 00015889 msup3s
Ai=Lc = 00015889 microc 00017
= 0935817588 msup2
For a vertical cylindrical decanterAi = prodrsup2
r = 0935817588 prodr = 0545835318 m
Diameter= 1091670637 m
Taking the height as twice the diameter a reasonable value for a cylinder
Height = 2183341274 m
The position of the interface should be such that the band of droplets that collect at the interface waiting to coalesce and cross the interface does not extend to the bottom (or top) of the vessel The depth of the dispersion band is a function of the liquid flow rate and the interfacial area A value of to per cent of the decanter height is usually taken for the design purposes
Take the dispersion band as 10 per cent of the height = 021833mThe residence time of the droplets in the dispersion band = 021833 = 021833microd 00017 =1285926 s (approx 2 min)
This is satisfactory time a time of 2 to 5 min is normally recommended Thus the size of the water (continuous heavy phase) droplets that could be entrained with benzene (light phase) will be
Velocity of benzene phase = 4543812 X 1 X 1 873811 3600093581
=0001543511 ms =1543511mms
30 of 72
So from equation ( ) So the entrained droplet size will be =00015435 X 18 X 0000604 frac12 981 X (99704-873812)
=00001178 m=1178 microm
which is satisfactory below 150 microm
Piping arrangement
To minimize entrainment by the jet of liquid entering the vessel the inlet velocity for a decanter should keep below 1 ms
The velocity from static mixer= 066 ms
Flow rate= 4543812 + 570311 X 1 87381 99704 3600
= 0003033345msup3s
Area of pipe= flow ratevelocity
= 0003033345066
= 0004554572msup2
Pipe diameter =0004554572 x 4prod
= 0076158749 m =29983 inch (approx 3 in)
31 of 72
32 of 72
33 of 72
34 of 72
35 of 72
36 of 72
37 of 72
PROJECT II
CALULATING THE DEW POINT
This project is about the study and evaluation of the performance of the compressors in the Hydrobon section of the LAB plant which is installed to optimize the purity of hydrogen coming from the product separators The compressors in this section include recycle gas compressor and make-up gas compressorThe purity of hydrogen can be increased upto 90
This project will give the company an overall view of this loop The plant is running well about its installed capacity(131-140) The company wants to retain the purity level of nearly 90 for hydrogen even after operating above installed capacity Hence the current project will give the company an idea of the current hydrogen quality(purity) which is obtained and give an idea about changes if any to be made to existing process set-up
HYDROBON REACTOR
Hydrobon reactor is designed to remove contaminants present in the raw kerosene without changing the boiling range The hydrocarbon is passed through a 2 bed reactor feed with S 12 catalyst through a feed effluent exchanger and charge heater which maintain the required reaction temperature(310 c) The reaction required hydrogen gas which is supplied from pacol net gas generated from back end and tattoray hydrogen from PX plantThe reaction charge is heated to the reaction temperature in the charge heater enters the reactor from the top and is distributed over the catalyst bed Catalytic hydrogenation takes place in the reactor The impurities react with hydrogen and form salts which are subsequently separated and finally removed in sour water stripper The reactor effluents after separation is fed to the product stripper to remove lighters and hydrotreated kerosene is fed to molex unit The sulfur and nitrogen levels are reduced to 1 ppm or less
PARAMETERS DESIGN ACTUALPlant load() 100 115Hydrobon feed rate(mthr) 58 60Temperature 416 310Pressure (kgcm2 g) 822 62H2HC ratio 385 460Recycle hydrogen purity(mole)
75 min 95
Hydrobon feed specificationa Bromine
index(mg100gm)800 800
38 of 72
b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
39 of 72
HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
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4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
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FLOW DIAGRAM OF HYDROBON SECTION
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Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
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nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
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Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
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DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
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ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
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Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
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Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
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Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
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=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
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Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
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Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
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Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
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Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
1) The Normal paraffin produced in LAB plant is normally used for captive consumption for producing LAB
2) The main customer of LAB is Ms Hindustan Lever and Procter amp Gamble Ltd and their subsidiary
3) The LAB is exported to Europe American African and Asian countries4) The light and Heavy normal paraffin is used to manufacture Chlorinated Paraffin Wax5) Heavy alkyl Benzene is used as lubricants in oil industry
Utility system in LAB plant
Hot oil system
There are two Hot oil Heaters available in LAB plant one for Front End and other is for Back End The Heaters are fired with furnace oil LSHS and off gases from process
The Hot oil (Dow Therm) which is thermic fluid is heated in these Hot oil heaters
The all heat inputs to the column preheater are given by circulating Hot oil at supply temperature of 330 DegC
Effluent System
The effluent generated in LAB plant mainly constitute
a) Fluoride Maximum limit lt 10 ppmb) Oil Maximum limit lt 10 ppm
For reduction of fluoride in effluent water LAB plant have two neutralisation basins where effluent from HF area is collected and then reacted with Lime (CaCO3) to reduce fluoride content below 10ppm
For reduction of oil in effluent water LAB plant have CPI separator installed to separate oil from effluent water The oil separated is send to Slope oil storage
In addition to this there is hydrocarbon pit installed in front end to collect pump and filter drains which is being blended in return kerosene to reduce oil load in effluent systemThere all oil collection pits installed in storm water channels to avoid oil going into the river via gates
20 of 72
Cooling water systemFor cooling the final products Byproducts to normal ambient temperatures the products byproducts are cooled in coolers The cooling media used is water There are three cooling towers installed in LAB planta) HF cooling tower it is separate cooling tower to avoid HF ingrace in coolers in non-HF
areab) Front End Cooling towerc) Back End cooling tower
Fin Fan coolers The distillation columns overheads are condensed in air-cooled fin fan coolers The advantage of these coolers over water-cooled coolers is low operating cost
Safety measures taken in LAB Plant
1) Safety Interlocks for tripping the operation of equipments in case process variables touches maximum allowable value
2) Flare system for burning excess gases from process3) Infra red detection system for Pacol Reactor and Hot pumps 4) Hydrocarbon detection system for detecting hydrocarbon leakages5) H2S detection system and siren for detecting H2S gas leakages 6) HF Detection system for detecting HF leakages7) Schedule HF leak testing of HF flanges8) Application of HF detection paints to all HF flanges to detect HF leak by decolouration9) Schedule Thickness survey of pipelines in HF area 10) Fire water sprinkler system for HF vessels Columns and pumps11) Fire water sprinkler system for Hot oil pumps12) Yellow boundary marking of HF area where personal protective equipments (PPErsquos) are
mandatory 13) Personal protective equipments (PPErsquos) for HF area Different types of PVC suits are defined
for different types of jobs ( A B C and D type)14) Separate breathing air reciprocating compressor for breathing air for C and D type PVC
suits in case of eemergency15) KOH scrubbing for venting from all HF equipments so that HF will not release into the
flare16) Daily Benzene monitoring with dragger tubes to detect any Benzene leaks from process17) Close draining system of HF and Benzene
21 of 72
PROJECT ndashI
The project is about developing a ldquoBENZENE-WATER WASHrdquo system to remove the impurities coming with fresh benzene that enters into benzene stripper and effects thefin-fan cooler The project is about developing such a scheme which will remove these impurities before entering the benzene stripper to eliminate the failure of fin-fan cooler
The scheme should also be such that it should not reduce the efficiency of the equipment and should be cost-effective
What is Benzene stripper
The high volatility of water dissolved in hydrocarbons is used in this column to obtain water-free benzene in the column bottoms which also removes any dissolved oxygen or non-condensibles in the benzene or off spec feeds Makeup benzene is fed to the overhead receiver on level control reset by the overhead receiver level controller It is refluxed via the overhead pump on flow control reset by the column bottom level controller and sent to the reaction section by the bottoms pump via the benzene stripper feedbottoms exchanger on flow control which is reset by the benzene column receiver level controller The benzene stripper receiver floats on the flare and is sized big enough to allow enough settling time for the water There is a small nitrogen flow via a conservation vent into the receiver vapor flare to maintain a slight nitrogen purge Water is collected in the boot and drained periodically whenever there is a boot high alarm Maintain a visible benzene water interface in the boot sight glass The benzene at the column bottom normally has a water content of less than 20ppm actually much lower if the column is operated well A moisture analyzer alarm high is provided The heat input to the column is provided by a hot oil reboiler with the hot oil flow controlled Off-spec material from the off-spec tank is normally rerun via the benzene stripper coming into the column receiver
What is the Issue
The benzene stripper column overheads are condensed in air-cooler (fin-fan coolers EC-301)The advantage of using this fin-fan cooler is the low operating cost no space constraint as are not on ground level etc This tube-bundle was failing at a frequency of once in a span of two years Failure analysis study was carried out and found that there are some impurities coming along with fresh benzene which are forming acidic solution after condensing in fin-fan This acidic solution formed was causing the repeated failure of tube-bundle
Water dosing was started upstream of the fin-fan bundle to dissolve out the impurities or to neutralize the acidic solution so that tubes can be saved This practice was started in 2008 Even after this modification the failures and continue and its difficult to analyze that what type of impurities are coming with benzene
22 of 72
So to eliminate this problem a scheme has been plotted to design a benzene scrubbing system This will be basically washing of benzene with DM water to remove the impurities before it enters the benzene stripper
The schematic diagram of this system is shown below
The scheme consists of a static mixture for mixing benzene and water for a particular residence time and at a particular velocity as required A gravity settler is for separating benzene and water on the basis of density difference
23 of 72
STATIC MIXER
This mixing device has no moving parts is simple and its cost can be quite reasonable when compared to mechanical driven mixers Static or motionless mixers are relatively new development and have proven to be effective for many specific and valuable process application It is useful for a wide range of viscosity fluids particularly useful in liquid-liquid mixing and also for some gas-liquid dispersion
The concept of motionless mixers is to achieve a uniform composition and temperature distribution in fluids flowing through the device The concept is build around a stationary rigid element placed in a pipe or cylinder that uses the energy of fluid flowing past to produce the mixing The unit becomes more efficient by adding additional static elements causing the flowing fluid elements to split rearrange recombine and split again to repeat the process lsquoxrsquo times for a uniform or homogeneous flowing stream is produced at discharge
Principle of operation
The static mixer unit is a series of fixed helical elements enclosed within a tubular housing
LIQUID ndash LIQUID SEPARATION(Decanters)
Separation of two liquid phases immiscible or partially miscible liquids is a common requirement in the process industries It is also frequently necessary to separate small quantities of entrained water from process streams The simplest form of equipment used to separate liquid phases is the gravity settling tank the decanter Various proprietary equipment is also used to promote coalescence and improve separation in difficult systems or where emulsions are likely to form Centrifugal separators are also used
Decanters (settlers)
Decanters are used to separate liquids where there is a sufficient difference in density between the liquids for the droplets to settle readily Decanters are essentially tanks which give sufficient residence time for the droplets of the dispersed phase to rise (or settle ) to the interface between the phases and coalesce
In an operating decanter there will be three distinct zones or bands clear heavy liquid separating dispersed liquid (the dispersion zone) and clear light liquid The position of the interface can be controlled with or without the use of instruments by use of a siphon take-off for the heavy liquid
24 of 72
Vertical decanter
The height of the take-off can be determined by making a pressure balance Neglecting friction loss in the pipes the pressure exerted by the combined height of the heavy and light liquid in the vessel must be balanced by the height of the heavy liquid in the take-off leg
(z1-z3)Ρ1g + z3 Ρ2g= z2 Ρ2g
z2 = (z1-z3) Ρ1 + z3 (1)Ρ2
WhereZ1= height from datum to light liquid overflow m Z2=height from datum to heavy liquid overflow m Z3=height from datum to interface m Ρ1=density of the light liquid kgmsup3 Ρ2=density of the heavy liquid kg msup3
The height of the liquid interface should be measured accurately when the liquid densities are close when one component is present only in small quantities or when the throughput is very small A typical scheme for the automatic control of the interface using a level instrument that can detect the position of the interface is shown in the diagram below Where one phase is present only in small amounts it is often recycled to the decanter feed to give more stable operation
25 of 72
CALCULATIONS
STATIC MIXER DESIGN
Required data
1 Physical properties of materials Density kgmsup3
Viscosity Pas = 0001Cp
2 Pressure drop Pressure drop in static mixer is best described by comparison with pipe flow
3 Geometrical parameters Diameter m
Type of static mixer constant (k)
Length (l) m
4 Process variables
Flow rate msup3s TemperaturedegC Pressure bar
26 of 72
Pressure drop calculation
a) Velocity (v)
V = Qπ4 Dsup2
b) Reynoldsrsquos number(Re)
Re= dvρμ
c) Pressure drop (Δp)For Re lt50 Δp =k1x μ x l xQd dsup3
k1= laminar flow constant
For Re gt10sup3 Δp =k2 x ρ x l x vsup2d 2
= k2 x Q x l x 8 x Qsup2d prodsup2 d⁴
k2= turbulent flow constant
Pipe diameter Flow seems to be turbulent as both the materials (B2+ H2O) are not viscous
D =39Q ⁰ ⁴⁵ ρ sup1sup3⁰
Q =52 + 572 = 1092msup3hr = 303 x 10macrsup3msup3s= 38564 ftsup3hr
Ρ = 926328 kgmsup3 =57828 lbftsup3
D =39 x Q ⁰ ⁴⁵ x ρ sup1sup3⁰
D =39 x (38564) ⁰ ⁴⁵ x (57828) sup1sup3⁰ 3600
D= 24 inch = 25 inch = 00635m
27 of 72
Velocity(v)
V =4 Q proddsup2
= 303 x 10macrsup3 msup3s x 4 314 x (00635)sup2
= 0957 ms (approx 1ms)
Reynoldrsquosnumber(Re)
Re = dvρ Μ = 00635 x 1 x 926328 0572
Re =103 x 10⁵
Thus the flow is highly turbulent
Flow regime Reynoldrsquos no(Re)
No of element No of elements to add if viscosity ratio between fluids exceeds 10001
No of elements to add if volumetric ratio between fluids exceeds 1001
Laminar lt1 24 6 61-10 18 6 611-50 14 6 651-100 12 6 6101-500 10 6 6
Transitional 501-1000 8 4 41001-2000 6 4 4
Turbulent 2001-5000 4 2 25001+ 2 2 2
Thus from the above table the mixer will have 2 elements
The mixer length will be based on the number of elements required An approximate length can be determined by multiplying the number of elements by 15
Mixer length = 15 x 2 =3
28 of 72
For turbulent flow applications it is generally recommended that a minimum velocity of 10 ftsec be maintained
V= 0408 x QDsup2 = 0408 x 4813sup2 = 218 ftsec =066 ms
DECANTER DESIGN
Benzene Water
Flow rate (msup3h) 52 572
Flow rate (kgh) 4543812 570311
Density (kgmsup3) 87381 99704
Viscosity (Pas) 0000604 000089
Take Dd = 150microm
microd = (150 Х 10ˉ⁶)sup2 Х 981 Х (87381-99704) 18 Х 000089
microd = -169787 Х 10ˉsup3 ms = -17 mms (rising)
As the flow rate is small we will use a vertical cylindrical vessel
The decanter vessel is sized on the basis that the velocity of the continuous phase must be less than settling velocity of the droplets of the dispersed phase Plug flow is assumed and the velocity of the continuous phase calculated using the area of the interfacemicroc =Lclt microdAiWhere microd = settling velocity of the dispersed phase droplets msmicroc = velocity of the continuous phase msLc = continuous phase volumetric flow rate msup3sAi = area of the interface msup2
29 of 72
Lc = 570311 X 1 99704 3600
= 00015889 msup3s
Ai=Lc = 00015889 microc 00017
= 0935817588 msup2
For a vertical cylindrical decanterAi = prodrsup2
r = 0935817588 prodr = 0545835318 m
Diameter= 1091670637 m
Taking the height as twice the diameter a reasonable value for a cylinder
Height = 2183341274 m
The position of the interface should be such that the band of droplets that collect at the interface waiting to coalesce and cross the interface does not extend to the bottom (or top) of the vessel The depth of the dispersion band is a function of the liquid flow rate and the interfacial area A value of to per cent of the decanter height is usually taken for the design purposes
Take the dispersion band as 10 per cent of the height = 021833mThe residence time of the droplets in the dispersion band = 021833 = 021833microd 00017 =1285926 s (approx 2 min)
This is satisfactory time a time of 2 to 5 min is normally recommended Thus the size of the water (continuous heavy phase) droplets that could be entrained with benzene (light phase) will be
Velocity of benzene phase = 4543812 X 1 X 1 873811 3600093581
=0001543511 ms =1543511mms
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So from equation ( ) So the entrained droplet size will be =00015435 X 18 X 0000604 frac12 981 X (99704-873812)
=00001178 m=1178 microm
which is satisfactory below 150 microm
Piping arrangement
To minimize entrainment by the jet of liquid entering the vessel the inlet velocity for a decanter should keep below 1 ms
The velocity from static mixer= 066 ms
Flow rate= 4543812 + 570311 X 1 87381 99704 3600
= 0003033345msup3s
Area of pipe= flow ratevelocity
= 0003033345066
= 0004554572msup2
Pipe diameter =0004554572 x 4prod
= 0076158749 m =29983 inch (approx 3 in)
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PROJECT II
CALULATING THE DEW POINT
This project is about the study and evaluation of the performance of the compressors in the Hydrobon section of the LAB plant which is installed to optimize the purity of hydrogen coming from the product separators The compressors in this section include recycle gas compressor and make-up gas compressorThe purity of hydrogen can be increased upto 90
This project will give the company an overall view of this loop The plant is running well about its installed capacity(131-140) The company wants to retain the purity level of nearly 90 for hydrogen even after operating above installed capacity Hence the current project will give the company an idea of the current hydrogen quality(purity) which is obtained and give an idea about changes if any to be made to existing process set-up
HYDROBON REACTOR
Hydrobon reactor is designed to remove contaminants present in the raw kerosene without changing the boiling range The hydrocarbon is passed through a 2 bed reactor feed with S 12 catalyst through a feed effluent exchanger and charge heater which maintain the required reaction temperature(310 c) The reaction required hydrogen gas which is supplied from pacol net gas generated from back end and tattoray hydrogen from PX plantThe reaction charge is heated to the reaction temperature in the charge heater enters the reactor from the top and is distributed over the catalyst bed Catalytic hydrogenation takes place in the reactor The impurities react with hydrogen and form salts which are subsequently separated and finally removed in sour water stripper The reactor effluents after separation is fed to the product stripper to remove lighters and hydrotreated kerosene is fed to molex unit The sulfur and nitrogen levels are reduced to 1 ppm or less
PARAMETERS DESIGN ACTUALPlant load() 100 115Hydrobon feed rate(mthr) 58 60Temperature 416 310Pressure (kgcm2 g) 822 62H2HC ratio 385 460Recycle hydrogen purity(mole)
75 min 95
Hydrobon feed specificationa Bromine
index(mg100gm)800 800
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b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
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HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
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4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
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FLOW DIAGRAM OF HYDROBON SECTION
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Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
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nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
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Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
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DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
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ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
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Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
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Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
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Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
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=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
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Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
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Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
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Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
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Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
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Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
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Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
Cooling water systemFor cooling the final products Byproducts to normal ambient temperatures the products byproducts are cooled in coolers The cooling media used is water There are three cooling towers installed in LAB planta) HF cooling tower it is separate cooling tower to avoid HF ingrace in coolers in non-HF
areab) Front End Cooling towerc) Back End cooling tower
Fin Fan coolers The distillation columns overheads are condensed in air-cooled fin fan coolers The advantage of these coolers over water-cooled coolers is low operating cost
Safety measures taken in LAB Plant
1) Safety Interlocks for tripping the operation of equipments in case process variables touches maximum allowable value
2) Flare system for burning excess gases from process3) Infra red detection system for Pacol Reactor and Hot pumps 4) Hydrocarbon detection system for detecting hydrocarbon leakages5) H2S detection system and siren for detecting H2S gas leakages 6) HF Detection system for detecting HF leakages7) Schedule HF leak testing of HF flanges8) Application of HF detection paints to all HF flanges to detect HF leak by decolouration9) Schedule Thickness survey of pipelines in HF area 10) Fire water sprinkler system for HF vessels Columns and pumps11) Fire water sprinkler system for Hot oil pumps12) Yellow boundary marking of HF area where personal protective equipments (PPErsquos) are
mandatory 13) Personal protective equipments (PPErsquos) for HF area Different types of PVC suits are defined
for different types of jobs ( A B C and D type)14) Separate breathing air reciprocating compressor for breathing air for C and D type PVC
suits in case of eemergency15) KOH scrubbing for venting from all HF equipments so that HF will not release into the
flare16) Daily Benzene monitoring with dragger tubes to detect any Benzene leaks from process17) Close draining system of HF and Benzene
21 of 72
PROJECT ndashI
The project is about developing a ldquoBENZENE-WATER WASHrdquo system to remove the impurities coming with fresh benzene that enters into benzene stripper and effects thefin-fan cooler The project is about developing such a scheme which will remove these impurities before entering the benzene stripper to eliminate the failure of fin-fan cooler
The scheme should also be such that it should not reduce the efficiency of the equipment and should be cost-effective
What is Benzene stripper
The high volatility of water dissolved in hydrocarbons is used in this column to obtain water-free benzene in the column bottoms which also removes any dissolved oxygen or non-condensibles in the benzene or off spec feeds Makeup benzene is fed to the overhead receiver on level control reset by the overhead receiver level controller It is refluxed via the overhead pump on flow control reset by the column bottom level controller and sent to the reaction section by the bottoms pump via the benzene stripper feedbottoms exchanger on flow control which is reset by the benzene column receiver level controller The benzene stripper receiver floats on the flare and is sized big enough to allow enough settling time for the water There is a small nitrogen flow via a conservation vent into the receiver vapor flare to maintain a slight nitrogen purge Water is collected in the boot and drained periodically whenever there is a boot high alarm Maintain a visible benzene water interface in the boot sight glass The benzene at the column bottom normally has a water content of less than 20ppm actually much lower if the column is operated well A moisture analyzer alarm high is provided The heat input to the column is provided by a hot oil reboiler with the hot oil flow controlled Off-spec material from the off-spec tank is normally rerun via the benzene stripper coming into the column receiver
What is the Issue
The benzene stripper column overheads are condensed in air-cooler (fin-fan coolers EC-301)The advantage of using this fin-fan cooler is the low operating cost no space constraint as are not on ground level etc This tube-bundle was failing at a frequency of once in a span of two years Failure analysis study was carried out and found that there are some impurities coming along with fresh benzene which are forming acidic solution after condensing in fin-fan This acidic solution formed was causing the repeated failure of tube-bundle
Water dosing was started upstream of the fin-fan bundle to dissolve out the impurities or to neutralize the acidic solution so that tubes can be saved This practice was started in 2008 Even after this modification the failures and continue and its difficult to analyze that what type of impurities are coming with benzene
22 of 72
So to eliminate this problem a scheme has been plotted to design a benzene scrubbing system This will be basically washing of benzene with DM water to remove the impurities before it enters the benzene stripper
The schematic diagram of this system is shown below
The scheme consists of a static mixture for mixing benzene and water for a particular residence time and at a particular velocity as required A gravity settler is for separating benzene and water on the basis of density difference
23 of 72
STATIC MIXER
This mixing device has no moving parts is simple and its cost can be quite reasonable when compared to mechanical driven mixers Static or motionless mixers are relatively new development and have proven to be effective for many specific and valuable process application It is useful for a wide range of viscosity fluids particularly useful in liquid-liquid mixing and also for some gas-liquid dispersion
The concept of motionless mixers is to achieve a uniform composition and temperature distribution in fluids flowing through the device The concept is build around a stationary rigid element placed in a pipe or cylinder that uses the energy of fluid flowing past to produce the mixing The unit becomes more efficient by adding additional static elements causing the flowing fluid elements to split rearrange recombine and split again to repeat the process lsquoxrsquo times for a uniform or homogeneous flowing stream is produced at discharge
Principle of operation
The static mixer unit is a series of fixed helical elements enclosed within a tubular housing
LIQUID ndash LIQUID SEPARATION(Decanters)
Separation of two liquid phases immiscible or partially miscible liquids is a common requirement in the process industries It is also frequently necessary to separate small quantities of entrained water from process streams The simplest form of equipment used to separate liquid phases is the gravity settling tank the decanter Various proprietary equipment is also used to promote coalescence and improve separation in difficult systems or where emulsions are likely to form Centrifugal separators are also used
Decanters (settlers)
Decanters are used to separate liquids where there is a sufficient difference in density between the liquids for the droplets to settle readily Decanters are essentially tanks which give sufficient residence time for the droplets of the dispersed phase to rise (or settle ) to the interface between the phases and coalesce
In an operating decanter there will be three distinct zones or bands clear heavy liquid separating dispersed liquid (the dispersion zone) and clear light liquid The position of the interface can be controlled with or without the use of instruments by use of a siphon take-off for the heavy liquid
24 of 72
Vertical decanter
The height of the take-off can be determined by making a pressure balance Neglecting friction loss in the pipes the pressure exerted by the combined height of the heavy and light liquid in the vessel must be balanced by the height of the heavy liquid in the take-off leg
(z1-z3)Ρ1g + z3 Ρ2g= z2 Ρ2g
z2 = (z1-z3) Ρ1 + z3 (1)Ρ2
WhereZ1= height from datum to light liquid overflow m Z2=height from datum to heavy liquid overflow m Z3=height from datum to interface m Ρ1=density of the light liquid kgmsup3 Ρ2=density of the heavy liquid kg msup3
The height of the liquid interface should be measured accurately when the liquid densities are close when one component is present only in small quantities or when the throughput is very small A typical scheme for the automatic control of the interface using a level instrument that can detect the position of the interface is shown in the diagram below Where one phase is present only in small amounts it is often recycled to the decanter feed to give more stable operation
25 of 72
CALCULATIONS
STATIC MIXER DESIGN
Required data
1 Physical properties of materials Density kgmsup3
Viscosity Pas = 0001Cp
2 Pressure drop Pressure drop in static mixer is best described by comparison with pipe flow
3 Geometrical parameters Diameter m
Type of static mixer constant (k)
Length (l) m
4 Process variables
Flow rate msup3s TemperaturedegC Pressure bar
26 of 72
Pressure drop calculation
a) Velocity (v)
V = Qπ4 Dsup2
b) Reynoldsrsquos number(Re)
Re= dvρμ
c) Pressure drop (Δp)For Re lt50 Δp =k1x μ x l xQd dsup3
k1= laminar flow constant
For Re gt10sup3 Δp =k2 x ρ x l x vsup2d 2
= k2 x Q x l x 8 x Qsup2d prodsup2 d⁴
k2= turbulent flow constant
Pipe diameter Flow seems to be turbulent as both the materials (B2+ H2O) are not viscous
D =39Q ⁰ ⁴⁵ ρ sup1sup3⁰
Q =52 + 572 = 1092msup3hr = 303 x 10macrsup3msup3s= 38564 ftsup3hr
Ρ = 926328 kgmsup3 =57828 lbftsup3
D =39 x Q ⁰ ⁴⁵ x ρ sup1sup3⁰
D =39 x (38564) ⁰ ⁴⁵ x (57828) sup1sup3⁰ 3600
D= 24 inch = 25 inch = 00635m
27 of 72
Velocity(v)
V =4 Q proddsup2
= 303 x 10macrsup3 msup3s x 4 314 x (00635)sup2
= 0957 ms (approx 1ms)
Reynoldrsquosnumber(Re)
Re = dvρ Μ = 00635 x 1 x 926328 0572
Re =103 x 10⁵
Thus the flow is highly turbulent
Flow regime Reynoldrsquos no(Re)
No of element No of elements to add if viscosity ratio between fluids exceeds 10001
No of elements to add if volumetric ratio between fluids exceeds 1001
Laminar lt1 24 6 61-10 18 6 611-50 14 6 651-100 12 6 6101-500 10 6 6
Transitional 501-1000 8 4 41001-2000 6 4 4
Turbulent 2001-5000 4 2 25001+ 2 2 2
Thus from the above table the mixer will have 2 elements
The mixer length will be based on the number of elements required An approximate length can be determined by multiplying the number of elements by 15
Mixer length = 15 x 2 =3
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For turbulent flow applications it is generally recommended that a minimum velocity of 10 ftsec be maintained
V= 0408 x QDsup2 = 0408 x 4813sup2 = 218 ftsec =066 ms
DECANTER DESIGN
Benzene Water
Flow rate (msup3h) 52 572
Flow rate (kgh) 4543812 570311
Density (kgmsup3) 87381 99704
Viscosity (Pas) 0000604 000089
Take Dd = 150microm
microd = (150 Х 10ˉ⁶)sup2 Х 981 Х (87381-99704) 18 Х 000089
microd = -169787 Х 10ˉsup3 ms = -17 mms (rising)
As the flow rate is small we will use a vertical cylindrical vessel
The decanter vessel is sized on the basis that the velocity of the continuous phase must be less than settling velocity of the droplets of the dispersed phase Plug flow is assumed and the velocity of the continuous phase calculated using the area of the interfacemicroc =Lclt microdAiWhere microd = settling velocity of the dispersed phase droplets msmicroc = velocity of the continuous phase msLc = continuous phase volumetric flow rate msup3sAi = area of the interface msup2
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Lc = 570311 X 1 99704 3600
= 00015889 msup3s
Ai=Lc = 00015889 microc 00017
= 0935817588 msup2
For a vertical cylindrical decanterAi = prodrsup2
r = 0935817588 prodr = 0545835318 m
Diameter= 1091670637 m
Taking the height as twice the diameter a reasonable value for a cylinder
Height = 2183341274 m
The position of the interface should be such that the band of droplets that collect at the interface waiting to coalesce and cross the interface does not extend to the bottom (or top) of the vessel The depth of the dispersion band is a function of the liquid flow rate and the interfacial area A value of to per cent of the decanter height is usually taken for the design purposes
Take the dispersion band as 10 per cent of the height = 021833mThe residence time of the droplets in the dispersion band = 021833 = 021833microd 00017 =1285926 s (approx 2 min)
This is satisfactory time a time of 2 to 5 min is normally recommended Thus the size of the water (continuous heavy phase) droplets that could be entrained with benzene (light phase) will be
Velocity of benzene phase = 4543812 X 1 X 1 873811 3600093581
=0001543511 ms =1543511mms
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So from equation ( ) So the entrained droplet size will be =00015435 X 18 X 0000604 frac12 981 X (99704-873812)
=00001178 m=1178 microm
which is satisfactory below 150 microm
Piping arrangement
To minimize entrainment by the jet of liquid entering the vessel the inlet velocity for a decanter should keep below 1 ms
The velocity from static mixer= 066 ms
Flow rate= 4543812 + 570311 X 1 87381 99704 3600
= 0003033345msup3s
Area of pipe= flow ratevelocity
= 0003033345066
= 0004554572msup2
Pipe diameter =0004554572 x 4prod
= 0076158749 m =29983 inch (approx 3 in)
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PROJECT II
CALULATING THE DEW POINT
This project is about the study and evaluation of the performance of the compressors in the Hydrobon section of the LAB plant which is installed to optimize the purity of hydrogen coming from the product separators The compressors in this section include recycle gas compressor and make-up gas compressorThe purity of hydrogen can be increased upto 90
This project will give the company an overall view of this loop The plant is running well about its installed capacity(131-140) The company wants to retain the purity level of nearly 90 for hydrogen even after operating above installed capacity Hence the current project will give the company an idea of the current hydrogen quality(purity) which is obtained and give an idea about changes if any to be made to existing process set-up
HYDROBON REACTOR
Hydrobon reactor is designed to remove contaminants present in the raw kerosene without changing the boiling range The hydrocarbon is passed through a 2 bed reactor feed with S 12 catalyst through a feed effluent exchanger and charge heater which maintain the required reaction temperature(310 c) The reaction required hydrogen gas which is supplied from pacol net gas generated from back end and tattoray hydrogen from PX plantThe reaction charge is heated to the reaction temperature in the charge heater enters the reactor from the top and is distributed over the catalyst bed Catalytic hydrogenation takes place in the reactor The impurities react with hydrogen and form salts which are subsequently separated and finally removed in sour water stripper The reactor effluents after separation is fed to the product stripper to remove lighters and hydrotreated kerosene is fed to molex unit The sulfur and nitrogen levels are reduced to 1 ppm or less
PARAMETERS DESIGN ACTUALPlant load() 100 115Hydrobon feed rate(mthr) 58 60Temperature 416 310Pressure (kgcm2 g) 822 62H2HC ratio 385 460Recycle hydrogen purity(mole)
75 min 95
Hydrobon feed specificationa Bromine
index(mg100gm)800 800
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b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
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HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
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4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
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FLOW DIAGRAM OF HYDROBON SECTION
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Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
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nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
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Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
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DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
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ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
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Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
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Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
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Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
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=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
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Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
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Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
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Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
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Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
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Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
PROJECT ndashI
The project is about developing a ldquoBENZENE-WATER WASHrdquo system to remove the impurities coming with fresh benzene that enters into benzene stripper and effects thefin-fan cooler The project is about developing such a scheme which will remove these impurities before entering the benzene stripper to eliminate the failure of fin-fan cooler
The scheme should also be such that it should not reduce the efficiency of the equipment and should be cost-effective
What is Benzene stripper
The high volatility of water dissolved in hydrocarbons is used in this column to obtain water-free benzene in the column bottoms which also removes any dissolved oxygen or non-condensibles in the benzene or off spec feeds Makeup benzene is fed to the overhead receiver on level control reset by the overhead receiver level controller It is refluxed via the overhead pump on flow control reset by the column bottom level controller and sent to the reaction section by the bottoms pump via the benzene stripper feedbottoms exchanger on flow control which is reset by the benzene column receiver level controller The benzene stripper receiver floats on the flare and is sized big enough to allow enough settling time for the water There is a small nitrogen flow via a conservation vent into the receiver vapor flare to maintain a slight nitrogen purge Water is collected in the boot and drained periodically whenever there is a boot high alarm Maintain a visible benzene water interface in the boot sight glass The benzene at the column bottom normally has a water content of less than 20ppm actually much lower if the column is operated well A moisture analyzer alarm high is provided The heat input to the column is provided by a hot oil reboiler with the hot oil flow controlled Off-spec material from the off-spec tank is normally rerun via the benzene stripper coming into the column receiver
What is the Issue
The benzene stripper column overheads are condensed in air-cooler (fin-fan coolers EC-301)The advantage of using this fin-fan cooler is the low operating cost no space constraint as are not on ground level etc This tube-bundle was failing at a frequency of once in a span of two years Failure analysis study was carried out and found that there are some impurities coming along with fresh benzene which are forming acidic solution after condensing in fin-fan This acidic solution formed was causing the repeated failure of tube-bundle
Water dosing was started upstream of the fin-fan bundle to dissolve out the impurities or to neutralize the acidic solution so that tubes can be saved This practice was started in 2008 Even after this modification the failures and continue and its difficult to analyze that what type of impurities are coming with benzene
22 of 72
So to eliminate this problem a scheme has been plotted to design a benzene scrubbing system This will be basically washing of benzene with DM water to remove the impurities before it enters the benzene stripper
The schematic diagram of this system is shown below
The scheme consists of a static mixture for mixing benzene and water for a particular residence time and at a particular velocity as required A gravity settler is for separating benzene and water on the basis of density difference
23 of 72
STATIC MIXER
This mixing device has no moving parts is simple and its cost can be quite reasonable when compared to mechanical driven mixers Static or motionless mixers are relatively new development and have proven to be effective for many specific and valuable process application It is useful for a wide range of viscosity fluids particularly useful in liquid-liquid mixing and also for some gas-liquid dispersion
The concept of motionless mixers is to achieve a uniform composition and temperature distribution in fluids flowing through the device The concept is build around a stationary rigid element placed in a pipe or cylinder that uses the energy of fluid flowing past to produce the mixing The unit becomes more efficient by adding additional static elements causing the flowing fluid elements to split rearrange recombine and split again to repeat the process lsquoxrsquo times for a uniform or homogeneous flowing stream is produced at discharge
Principle of operation
The static mixer unit is a series of fixed helical elements enclosed within a tubular housing
LIQUID ndash LIQUID SEPARATION(Decanters)
Separation of two liquid phases immiscible or partially miscible liquids is a common requirement in the process industries It is also frequently necessary to separate small quantities of entrained water from process streams The simplest form of equipment used to separate liquid phases is the gravity settling tank the decanter Various proprietary equipment is also used to promote coalescence and improve separation in difficult systems or where emulsions are likely to form Centrifugal separators are also used
Decanters (settlers)
Decanters are used to separate liquids where there is a sufficient difference in density between the liquids for the droplets to settle readily Decanters are essentially tanks which give sufficient residence time for the droplets of the dispersed phase to rise (or settle ) to the interface between the phases and coalesce
In an operating decanter there will be three distinct zones or bands clear heavy liquid separating dispersed liquid (the dispersion zone) and clear light liquid The position of the interface can be controlled with or without the use of instruments by use of a siphon take-off for the heavy liquid
24 of 72
Vertical decanter
The height of the take-off can be determined by making a pressure balance Neglecting friction loss in the pipes the pressure exerted by the combined height of the heavy and light liquid in the vessel must be balanced by the height of the heavy liquid in the take-off leg
(z1-z3)Ρ1g + z3 Ρ2g= z2 Ρ2g
z2 = (z1-z3) Ρ1 + z3 (1)Ρ2
WhereZ1= height from datum to light liquid overflow m Z2=height from datum to heavy liquid overflow m Z3=height from datum to interface m Ρ1=density of the light liquid kgmsup3 Ρ2=density of the heavy liquid kg msup3
The height of the liquid interface should be measured accurately when the liquid densities are close when one component is present only in small quantities or when the throughput is very small A typical scheme for the automatic control of the interface using a level instrument that can detect the position of the interface is shown in the diagram below Where one phase is present only in small amounts it is often recycled to the decanter feed to give more stable operation
25 of 72
CALCULATIONS
STATIC MIXER DESIGN
Required data
1 Physical properties of materials Density kgmsup3
Viscosity Pas = 0001Cp
2 Pressure drop Pressure drop in static mixer is best described by comparison with pipe flow
3 Geometrical parameters Diameter m
Type of static mixer constant (k)
Length (l) m
4 Process variables
Flow rate msup3s TemperaturedegC Pressure bar
26 of 72
Pressure drop calculation
a) Velocity (v)
V = Qπ4 Dsup2
b) Reynoldsrsquos number(Re)
Re= dvρμ
c) Pressure drop (Δp)For Re lt50 Δp =k1x μ x l xQd dsup3
k1= laminar flow constant
For Re gt10sup3 Δp =k2 x ρ x l x vsup2d 2
= k2 x Q x l x 8 x Qsup2d prodsup2 d⁴
k2= turbulent flow constant
Pipe diameter Flow seems to be turbulent as both the materials (B2+ H2O) are not viscous
D =39Q ⁰ ⁴⁵ ρ sup1sup3⁰
Q =52 + 572 = 1092msup3hr = 303 x 10macrsup3msup3s= 38564 ftsup3hr
Ρ = 926328 kgmsup3 =57828 lbftsup3
D =39 x Q ⁰ ⁴⁵ x ρ sup1sup3⁰
D =39 x (38564) ⁰ ⁴⁵ x (57828) sup1sup3⁰ 3600
D= 24 inch = 25 inch = 00635m
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Velocity(v)
V =4 Q proddsup2
= 303 x 10macrsup3 msup3s x 4 314 x (00635)sup2
= 0957 ms (approx 1ms)
Reynoldrsquosnumber(Re)
Re = dvρ Μ = 00635 x 1 x 926328 0572
Re =103 x 10⁵
Thus the flow is highly turbulent
Flow regime Reynoldrsquos no(Re)
No of element No of elements to add if viscosity ratio between fluids exceeds 10001
No of elements to add if volumetric ratio between fluids exceeds 1001
Laminar lt1 24 6 61-10 18 6 611-50 14 6 651-100 12 6 6101-500 10 6 6
Transitional 501-1000 8 4 41001-2000 6 4 4
Turbulent 2001-5000 4 2 25001+ 2 2 2
Thus from the above table the mixer will have 2 elements
The mixer length will be based on the number of elements required An approximate length can be determined by multiplying the number of elements by 15
Mixer length = 15 x 2 =3
28 of 72
For turbulent flow applications it is generally recommended that a minimum velocity of 10 ftsec be maintained
V= 0408 x QDsup2 = 0408 x 4813sup2 = 218 ftsec =066 ms
DECANTER DESIGN
Benzene Water
Flow rate (msup3h) 52 572
Flow rate (kgh) 4543812 570311
Density (kgmsup3) 87381 99704
Viscosity (Pas) 0000604 000089
Take Dd = 150microm
microd = (150 Х 10ˉ⁶)sup2 Х 981 Х (87381-99704) 18 Х 000089
microd = -169787 Х 10ˉsup3 ms = -17 mms (rising)
As the flow rate is small we will use a vertical cylindrical vessel
The decanter vessel is sized on the basis that the velocity of the continuous phase must be less than settling velocity of the droplets of the dispersed phase Plug flow is assumed and the velocity of the continuous phase calculated using the area of the interfacemicroc =Lclt microdAiWhere microd = settling velocity of the dispersed phase droplets msmicroc = velocity of the continuous phase msLc = continuous phase volumetric flow rate msup3sAi = area of the interface msup2
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Lc = 570311 X 1 99704 3600
= 00015889 msup3s
Ai=Lc = 00015889 microc 00017
= 0935817588 msup2
For a vertical cylindrical decanterAi = prodrsup2
r = 0935817588 prodr = 0545835318 m
Diameter= 1091670637 m
Taking the height as twice the diameter a reasonable value for a cylinder
Height = 2183341274 m
The position of the interface should be such that the band of droplets that collect at the interface waiting to coalesce and cross the interface does not extend to the bottom (or top) of the vessel The depth of the dispersion band is a function of the liquid flow rate and the interfacial area A value of to per cent of the decanter height is usually taken for the design purposes
Take the dispersion band as 10 per cent of the height = 021833mThe residence time of the droplets in the dispersion band = 021833 = 021833microd 00017 =1285926 s (approx 2 min)
This is satisfactory time a time of 2 to 5 min is normally recommended Thus the size of the water (continuous heavy phase) droplets that could be entrained with benzene (light phase) will be
Velocity of benzene phase = 4543812 X 1 X 1 873811 3600093581
=0001543511 ms =1543511mms
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So from equation ( ) So the entrained droplet size will be =00015435 X 18 X 0000604 frac12 981 X (99704-873812)
=00001178 m=1178 microm
which is satisfactory below 150 microm
Piping arrangement
To minimize entrainment by the jet of liquid entering the vessel the inlet velocity for a decanter should keep below 1 ms
The velocity from static mixer= 066 ms
Flow rate= 4543812 + 570311 X 1 87381 99704 3600
= 0003033345msup3s
Area of pipe= flow ratevelocity
= 0003033345066
= 0004554572msup2
Pipe diameter =0004554572 x 4prod
= 0076158749 m =29983 inch (approx 3 in)
31 of 72
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37 of 72
PROJECT II
CALULATING THE DEW POINT
This project is about the study and evaluation of the performance of the compressors in the Hydrobon section of the LAB plant which is installed to optimize the purity of hydrogen coming from the product separators The compressors in this section include recycle gas compressor and make-up gas compressorThe purity of hydrogen can be increased upto 90
This project will give the company an overall view of this loop The plant is running well about its installed capacity(131-140) The company wants to retain the purity level of nearly 90 for hydrogen even after operating above installed capacity Hence the current project will give the company an idea of the current hydrogen quality(purity) which is obtained and give an idea about changes if any to be made to existing process set-up
HYDROBON REACTOR
Hydrobon reactor is designed to remove contaminants present in the raw kerosene without changing the boiling range The hydrocarbon is passed through a 2 bed reactor feed with S 12 catalyst through a feed effluent exchanger and charge heater which maintain the required reaction temperature(310 c) The reaction required hydrogen gas which is supplied from pacol net gas generated from back end and tattoray hydrogen from PX plantThe reaction charge is heated to the reaction temperature in the charge heater enters the reactor from the top and is distributed over the catalyst bed Catalytic hydrogenation takes place in the reactor The impurities react with hydrogen and form salts which are subsequently separated and finally removed in sour water stripper The reactor effluents after separation is fed to the product stripper to remove lighters and hydrotreated kerosene is fed to molex unit The sulfur and nitrogen levels are reduced to 1 ppm or less
PARAMETERS DESIGN ACTUALPlant load() 100 115Hydrobon feed rate(mthr) 58 60Temperature 416 310Pressure (kgcm2 g) 822 62H2HC ratio 385 460Recycle hydrogen purity(mole)
75 min 95
Hydrobon feed specificationa Bromine
index(mg100gm)800 800
38 of 72
b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
39 of 72
HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
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4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
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FLOW DIAGRAM OF HYDROBON SECTION
42 of 72
Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
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nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
44 of 72
Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
45 of 72
DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
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ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
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Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
49 of 72
Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
50 of 72
Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
51 of 72
=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
52 of 72
Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
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Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
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Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
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Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
So to eliminate this problem a scheme has been plotted to design a benzene scrubbing system This will be basically washing of benzene with DM water to remove the impurities before it enters the benzene stripper
The schematic diagram of this system is shown below
The scheme consists of a static mixture for mixing benzene and water for a particular residence time and at a particular velocity as required A gravity settler is for separating benzene and water on the basis of density difference
23 of 72
STATIC MIXER
This mixing device has no moving parts is simple and its cost can be quite reasonable when compared to mechanical driven mixers Static or motionless mixers are relatively new development and have proven to be effective for many specific and valuable process application It is useful for a wide range of viscosity fluids particularly useful in liquid-liquid mixing and also for some gas-liquid dispersion
The concept of motionless mixers is to achieve a uniform composition and temperature distribution in fluids flowing through the device The concept is build around a stationary rigid element placed in a pipe or cylinder that uses the energy of fluid flowing past to produce the mixing The unit becomes more efficient by adding additional static elements causing the flowing fluid elements to split rearrange recombine and split again to repeat the process lsquoxrsquo times for a uniform or homogeneous flowing stream is produced at discharge
Principle of operation
The static mixer unit is a series of fixed helical elements enclosed within a tubular housing
LIQUID ndash LIQUID SEPARATION(Decanters)
Separation of two liquid phases immiscible or partially miscible liquids is a common requirement in the process industries It is also frequently necessary to separate small quantities of entrained water from process streams The simplest form of equipment used to separate liquid phases is the gravity settling tank the decanter Various proprietary equipment is also used to promote coalescence and improve separation in difficult systems or where emulsions are likely to form Centrifugal separators are also used
Decanters (settlers)
Decanters are used to separate liquids where there is a sufficient difference in density between the liquids for the droplets to settle readily Decanters are essentially tanks which give sufficient residence time for the droplets of the dispersed phase to rise (or settle ) to the interface between the phases and coalesce
In an operating decanter there will be three distinct zones or bands clear heavy liquid separating dispersed liquid (the dispersion zone) and clear light liquid The position of the interface can be controlled with or without the use of instruments by use of a siphon take-off for the heavy liquid
24 of 72
Vertical decanter
The height of the take-off can be determined by making a pressure balance Neglecting friction loss in the pipes the pressure exerted by the combined height of the heavy and light liquid in the vessel must be balanced by the height of the heavy liquid in the take-off leg
(z1-z3)Ρ1g + z3 Ρ2g= z2 Ρ2g
z2 = (z1-z3) Ρ1 + z3 (1)Ρ2
WhereZ1= height from datum to light liquid overflow m Z2=height from datum to heavy liquid overflow m Z3=height from datum to interface m Ρ1=density of the light liquid kgmsup3 Ρ2=density of the heavy liquid kg msup3
The height of the liquid interface should be measured accurately when the liquid densities are close when one component is present only in small quantities or when the throughput is very small A typical scheme for the automatic control of the interface using a level instrument that can detect the position of the interface is shown in the diagram below Where one phase is present only in small amounts it is often recycled to the decanter feed to give more stable operation
25 of 72
CALCULATIONS
STATIC MIXER DESIGN
Required data
1 Physical properties of materials Density kgmsup3
Viscosity Pas = 0001Cp
2 Pressure drop Pressure drop in static mixer is best described by comparison with pipe flow
3 Geometrical parameters Diameter m
Type of static mixer constant (k)
Length (l) m
4 Process variables
Flow rate msup3s TemperaturedegC Pressure bar
26 of 72
Pressure drop calculation
a) Velocity (v)
V = Qπ4 Dsup2
b) Reynoldsrsquos number(Re)
Re= dvρμ
c) Pressure drop (Δp)For Re lt50 Δp =k1x μ x l xQd dsup3
k1= laminar flow constant
For Re gt10sup3 Δp =k2 x ρ x l x vsup2d 2
= k2 x Q x l x 8 x Qsup2d prodsup2 d⁴
k2= turbulent flow constant
Pipe diameter Flow seems to be turbulent as both the materials (B2+ H2O) are not viscous
D =39Q ⁰ ⁴⁵ ρ sup1sup3⁰
Q =52 + 572 = 1092msup3hr = 303 x 10macrsup3msup3s= 38564 ftsup3hr
Ρ = 926328 kgmsup3 =57828 lbftsup3
D =39 x Q ⁰ ⁴⁵ x ρ sup1sup3⁰
D =39 x (38564) ⁰ ⁴⁵ x (57828) sup1sup3⁰ 3600
D= 24 inch = 25 inch = 00635m
27 of 72
Velocity(v)
V =4 Q proddsup2
= 303 x 10macrsup3 msup3s x 4 314 x (00635)sup2
= 0957 ms (approx 1ms)
Reynoldrsquosnumber(Re)
Re = dvρ Μ = 00635 x 1 x 926328 0572
Re =103 x 10⁵
Thus the flow is highly turbulent
Flow regime Reynoldrsquos no(Re)
No of element No of elements to add if viscosity ratio between fluids exceeds 10001
No of elements to add if volumetric ratio between fluids exceeds 1001
Laminar lt1 24 6 61-10 18 6 611-50 14 6 651-100 12 6 6101-500 10 6 6
Transitional 501-1000 8 4 41001-2000 6 4 4
Turbulent 2001-5000 4 2 25001+ 2 2 2
Thus from the above table the mixer will have 2 elements
The mixer length will be based on the number of elements required An approximate length can be determined by multiplying the number of elements by 15
Mixer length = 15 x 2 =3
28 of 72
For turbulent flow applications it is generally recommended that a minimum velocity of 10 ftsec be maintained
V= 0408 x QDsup2 = 0408 x 4813sup2 = 218 ftsec =066 ms
DECANTER DESIGN
Benzene Water
Flow rate (msup3h) 52 572
Flow rate (kgh) 4543812 570311
Density (kgmsup3) 87381 99704
Viscosity (Pas) 0000604 000089
Take Dd = 150microm
microd = (150 Х 10ˉ⁶)sup2 Х 981 Х (87381-99704) 18 Х 000089
microd = -169787 Х 10ˉsup3 ms = -17 mms (rising)
As the flow rate is small we will use a vertical cylindrical vessel
The decanter vessel is sized on the basis that the velocity of the continuous phase must be less than settling velocity of the droplets of the dispersed phase Plug flow is assumed and the velocity of the continuous phase calculated using the area of the interfacemicroc =Lclt microdAiWhere microd = settling velocity of the dispersed phase droplets msmicroc = velocity of the continuous phase msLc = continuous phase volumetric flow rate msup3sAi = area of the interface msup2
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Lc = 570311 X 1 99704 3600
= 00015889 msup3s
Ai=Lc = 00015889 microc 00017
= 0935817588 msup2
For a vertical cylindrical decanterAi = prodrsup2
r = 0935817588 prodr = 0545835318 m
Diameter= 1091670637 m
Taking the height as twice the diameter a reasonable value for a cylinder
Height = 2183341274 m
The position of the interface should be such that the band of droplets that collect at the interface waiting to coalesce and cross the interface does not extend to the bottom (or top) of the vessel The depth of the dispersion band is a function of the liquid flow rate and the interfacial area A value of to per cent of the decanter height is usually taken for the design purposes
Take the dispersion band as 10 per cent of the height = 021833mThe residence time of the droplets in the dispersion band = 021833 = 021833microd 00017 =1285926 s (approx 2 min)
This is satisfactory time a time of 2 to 5 min is normally recommended Thus the size of the water (continuous heavy phase) droplets that could be entrained with benzene (light phase) will be
Velocity of benzene phase = 4543812 X 1 X 1 873811 3600093581
=0001543511 ms =1543511mms
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So from equation ( ) So the entrained droplet size will be =00015435 X 18 X 0000604 frac12 981 X (99704-873812)
=00001178 m=1178 microm
which is satisfactory below 150 microm
Piping arrangement
To minimize entrainment by the jet of liquid entering the vessel the inlet velocity for a decanter should keep below 1 ms
The velocity from static mixer= 066 ms
Flow rate= 4543812 + 570311 X 1 87381 99704 3600
= 0003033345msup3s
Area of pipe= flow ratevelocity
= 0003033345066
= 0004554572msup2
Pipe diameter =0004554572 x 4prod
= 0076158749 m =29983 inch (approx 3 in)
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PROJECT II
CALULATING THE DEW POINT
This project is about the study and evaluation of the performance of the compressors in the Hydrobon section of the LAB plant which is installed to optimize the purity of hydrogen coming from the product separators The compressors in this section include recycle gas compressor and make-up gas compressorThe purity of hydrogen can be increased upto 90
This project will give the company an overall view of this loop The plant is running well about its installed capacity(131-140) The company wants to retain the purity level of nearly 90 for hydrogen even after operating above installed capacity Hence the current project will give the company an idea of the current hydrogen quality(purity) which is obtained and give an idea about changes if any to be made to existing process set-up
HYDROBON REACTOR
Hydrobon reactor is designed to remove contaminants present in the raw kerosene without changing the boiling range The hydrocarbon is passed through a 2 bed reactor feed with S 12 catalyst through a feed effluent exchanger and charge heater which maintain the required reaction temperature(310 c) The reaction required hydrogen gas which is supplied from pacol net gas generated from back end and tattoray hydrogen from PX plantThe reaction charge is heated to the reaction temperature in the charge heater enters the reactor from the top and is distributed over the catalyst bed Catalytic hydrogenation takes place in the reactor The impurities react with hydrogen and form salts which are subsequently separated and finally removed in sour water stripper The reactor effluents after separation is fed to the product stripper to remove lighters and hydrotreated kerosene is fed to molex unit The sulfur and nitrogen levels are reduced to 1 ppm or less
PARAMETERS DESIGN ACTUALPlant load() 100 115Hydrobon feed rate(mthr) 58 60Temperature 416 310Pressure (kgcm2 g) 822 62H2HC ratio 385 460Recycle hydrogen purity(mole)
75 min 95
Hydrobon feed specificationa Bromine
index(mg100gm)800 800
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b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
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HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
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4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
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FLOW DIAGRAM OF HYDROBON SECTION
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Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
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nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
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Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
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DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
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ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
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Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
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Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
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Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
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=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
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Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
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Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
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Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
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Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
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Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
STATIC MIXER
This mixing device has no moving parts is simple and its cost can be quite reasonable when compared to mechanical driven mixers Static or motionless mixers are relatively new development and have proven to be effective for many specific and valuable process application It is useful for a wide range of viscosity fluids particularly useful in liquid-liquid mixing and also for some gas-liquid dispersion
The concept of motionless mixers is to achieve a uniform composition and temperature distribution in fluids flowing through the device The concept is build around a stationary rigid element placed in a pipe or cylinder that uses the energy of fluid flowing past to produce the mixing The unit becomes more efficient by adding additional static elements causing the flowing fluid elements to split rearrange recombine and split again to repeat the process lsquoxrsquo times for a uniform or homogeneous flowing stream is produced at discharge
Principle of operation
The static mixer unit is a series of fixed helical elements enclosed within a tubular housing
LIQUID ndash LIQUID SEPARATION(Decanters)
Separation of two liquid phases immiscible or partially miscible liquids is a common requirement in the process industries It is also frequently necessary to separate small quantities of entrained water from process streams The simplest form of equipment used to separate liquid phases is the gravity settling tank the decanter Various proprietary equipment is also used to promote coalescence and improve separation in difficult systems or where emulsions are likely to form Centrifugal separators are also used
Decanters (settlers)
Decanters are used to separate liquids where there is a sufficient difference in density between the liquids for the droplets to settle readily Decanters are essentially tanks which give sufficient residence time for the droplets of the dispersed phase to rise (or settle ) to the interface between the phases and coalesce
In an operating decanter there will be three distinct zones or bands clear heavy liquid separating dispersed liquid (the dispersion zone) and clear light liquid The position of the interface can be controlled with or without the use of instruments by use of a siphon take-off for the heavy liquid
24 of 72
Vertical decanter
The height of the take-off can be determined by making a pressure balance Neglecting friction loss in the pipes the pressure exerted by the combined height of the heavy and light liquid in the vessel must be balanced by the height of the heavy liquid in the take-off leg
(z1-z3)Ρ1g + z3 Ρ2g= z2 Ρ2g
z2 = (z1-z3) Ρ1 + z3 (1)Ρ2
WhereZ1= height from datum to light liquid overflow m Z2=height from datum to heavy liquid overflow m Z3=height from datum to interface m Ρ1=density of the light liquid kgmsup3 Ρ2=density of the heavy liquid kg msup3
The height of the liquid interface should be measured accurately when the liquid densities are close when one component is present only in small quantities or when the throughput is very small A typical scheme for the automatic control of the interface using a level instrument that can detect the position of the interface is shown in the diagram below Where one phase is present only in small amounts it is often recycled to the decanter feed to give more stable operation
25 of 72
CALCULATIONS
STATIC MIXER DESIGN
Required data
1 Physical properties of materials Density kgmsup3
Viscosity Pas = 0001Cp
2 Pressure drop Pressure drop in static mixer is best described by comparison with pipe flow
3 Geometrical parameters Diameter m
Type of static mixer constant (k)
Length (l) m
4 Process variables
Flow rate msup3s TemperaturedegC Pressure bar
26 of 72
Pressure drop calculation
a) Velocity (v)
V = Qπ4 Dsup2
b) Reynoldsrsquos number(Re)
Re= dvρμ
c) Pressure drop (Δp)For Re lt50 Δp =k1x μ x l xQd dsup3
k1= laminar flow constant
For Re gt10sup3 Δp =k2 x ρ x l x vsup2d 2
= k2 x Q x l x 8 x Qsup2d prodsup2 d⁴
k2= turbulent flow constant
Pipe diameter Flow seems to be turbulent as both the materials (B2+ H2O) are not viscous
D =39Q ⁰ ⁴⁵ ρ sup1sup3⁰
Q =52 + 572 = 1092msup3hr = 303 x 10macrsup3msup3s= 38564 ftsup3hr
Ρ = 926328 kgmsup3 =57828 lbftsup3
D =39 x Q ⁰ ⁴⁵ x ρ sup1sup3⁰
D =39 x (38564) ⁰ ⁴⁵ x (57828) sup1sup3⁰ 3600
D= 24 inch = 25 inch = 00635m
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Velocity(v)
V =4 Q proddsup2
= 303 x 10macrsup3 msup3s x 4 314 x (00635)sup2
= 0957 ms (approx 1ms)
Reynoldrsquosnumber(Re)
Re = dvρ Μ = 00635 x 1 x 926328 0572
Re =103 x 10⁵
Thus the flow is highly turbulent
Flow regime Reynoldrsquos no(Re)
No of element No of elements to add if viscosity ratio between fluids exceeds 10001
No of elements to add if volumetric ratio between fluids exceeds 1001
Laminar lt1 24 6 61-10 18 6 611-50 14 6 651-100 12 6 6101-500 10 6 6
Transitional 501-1000 8 4 41001-2000 6 4 4
Turbulent 2001-5000 4 2 25001+ 2 2 2
Thus from the above table the mixer will have 2 elements
The mixer length will be based on the number of elements required An approximate length can be determined by multiplying the number of elements by 15
Mixer length = 15 x 2 =3
28 of 72
For turbulent flow applications it is generally recommended that a minimum velocity of 10 ftsec be maintained
V= 0408 x QDsup2 = 0408 x 4813sup2 = 218 ftsec =066 ms
DECANTER DESIGN
Benzene Water
Flow rate (msup3h) 52 572
Flow rate (kgh) 4543812 570311
Density (kgmsup3) 87381 99704
Viscosity (Pas) 0000604 000089
Take Dd = 150microm
microd = (150 Х 10ˉ⁶)sup2 Х 981 Х (87381-99704) 18 Х 000089
microd = -169787 Х 10ˉsup3 ms = -17 mms (rising)
As the flow rate is small we will use a vertical cylindrical vessel
The decanter vessel is sized on the basis that the velocity of the continuous phase must be less than settling velocity of the droplets of the dispersed phase Plug flow is assumed and the velocity of the continuous phase calculated using the area of the interfacemicroc =Lclt microdAiWhere microd = settling velocity of the dispersed phase droplets msmicroc = velocity of the continuous phase msLc = continuous phase volumetric flow rate msup3sAi = area of the interface msup2
29 of 72
Lc = 570311 X 1 99704 3600
= 00015889 msup3s
Ai=Lc = 00015889 microc 00017
= 0935817588 msup2
For a vertical cylindrical decanterAi = prodrsup2
r = 0935817588 prodr = 0545835318 m
Diameter= 1091670637 m
Taking the height as twice the diameter a reasonable value for a cylinder
Height = 2183341274 m
The position of the interface should be such that the band of droplets that collect at the interface waiting to coalesce and cross the interface does not extend to the bottom (or top) of the vessel The depth of the dispersion band is a function of the liquid flow rate and the interfacial area A value of to per cent of the decanter height is usually taken for the design purposes
Take the dispersion band as 10 per cent of the height = 021833mThe residence time of the droplets in the dispersion band = 021833 = 021833microd 00017 =1285926 s (approx 2 min)
This is satisfactory time a time of 2 to 5 min is normally recommended Thus the size of the water (continuous heavy phase) droplets that could be entrained with benzene (light phase) will be
Velocity of benzene phase = 4543812 X 1 X 1 873811 3600093581
=0001543511 ms =1543511mms
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So from equation ( ) So the entrained droplet size will be =00015435 X 18 X 0000604 frac12 981 X (99704-873812)
=00001178 m=1178 microm
which is satisfactory below 150 microm
Piping arrangement
To minimize entrainment by the jet of liquid entering the vessel the inlet velocity for a decanter should keep below 1 ms
The velocity from static mixer= 066 ms
Flow rate= 4543812 + 570311 X 1 87381 99704 3600
= 0003033345msup3s
Area of pipe= flow ratevelocity
= 0003033345066
= 0004554572msup2
Pipe diameter =0004554572 x 4prod
= 0076158749 m =29983 inch (approx 3 in)
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PROJECT II
CALULATING THE DEW POINT
This project is about the study and evaluation of the performance of the compressors in the Hydrobon section of the LAB plant which is installed to optimize the purity of hydrogen coming from the product separators The compressors in this section include recycle gas compressor and make-up gas compressorThe purity of hydrogen can be increased upto 90
This project will give the company an overall view of this loop The plant is running well about its installed capacity(131-140) The company wants to retain the purity level of nearly 90 for hydrogen even after operating above installed capacity Hence the current project will give the company an idea of the current hydrogen quality(purity) which is obtained and give an idea about changes if any to be made to existing process set-up
HYDROBON REACTOR
Hydrobon reactor is designed to remove contaminants present in the raw kerosene without changing the boiling range The hydrocarbon is passed through a 2 bed reactor feed with S 12 catalyst through a feed effluent exchanger and charge heater which maintain the required reaction temperature(310 c) The reaction required hydrogen gas which is supplied from pacol net gas generated from back end and tattoray hydrogen from PX plantThe reaction charge is heated to the reaction temperature in the charge heater enters the reactor from the top and is distributed over the catalyst bed Catalytic hydrogenation takes place in the reactor The impurities react with hydrogen and form salts which are subsequently separated and finally removed in sour water stripper The reactor effluents after separation is fed to the product stripper to remove lighters and hydrotreated kerosene is fed to molex unit The sulfur and nitrogen levels are reduced to 1 ppm or less
PARAMETERS DESIGN ACTUALPlant load() 100 115Hydrobon feed rate(mthr) 58 60Temperature 416 310Pressure (kgcm2 g) 822 62H2HC ratio 385 460Recycle hydrogen purity(mole)
75 min 95
Hydrobon feed specificationa Bromine
index(mg100gm)800 800
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b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
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HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
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4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
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FLOW DIAGRAM OF HYDROBON SECTION
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Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
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nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
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Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
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DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
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ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
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Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
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Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
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Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
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=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
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Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
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Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
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Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
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Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
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Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
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Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
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Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
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Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
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Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
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WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
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Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
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Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
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Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
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Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
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FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
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Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
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Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
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Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
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Vertical decanter
The height of the take-off can be determined by making a pressure balance Neglecting friction loss in the pipes the pressure exerted by the combined height of the heavy and light liquid in the vessel must be balanced by the height of the heavy liquid in the take-off leg
(z1-z3)Ρ1g + z3 Ρ2g= z2 Ρ2g
z2 = (z1-z3) Ρ1 + z3 (1)Ρ2
WhereZ1= height from datum to light liquid overflow m Z2=height from datum to heavy liquid overflow m Z3=height from datum to interface m Ρ1=density of the light liquid kgmsup3 Ρ2=density of the heavy liquid kg msup3
The height of the liquid interface should be measured accurately when the liquid densities are close when one component is present only in small quantities or when the throughput is very small A typical scheme for the automatic control of the interface using a level instrument that can detect the position of the interface is shown in the diagram below Where one phase is present only in small amounts it is often recycled to the decanter feed to give more stable operation
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CALCULATIONS
STATIC MIXER DESIGN
Required data
1 Physical properties of materials Density kgmsup3
Viscosity Pas = 0001Cp
2 Pressure drop Pressure drop in static mixer is best described by comparison with pipe flow
3 Geometrical parameters Diameter m
Type of static mixer constant (k)
Length (l) m
4 Process variables
Flow rate msup3s TemperaturedegC Pressure bar
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Pressure drop calculation
a) Velocity (v)
V = Qπ4 Dsup2
b) Reynoldsrsquos number(Re)
Re= dvρμ
c) Pressure drop (Δp)For Re lt50 Δp =k1x μ x l xQd dsup3
k1= laminar flow constant
For Re gt10sup3 Δp =k2 x ρ x l x vsup2d 2
= k2 x Q x l x 8 x Qsup2d prodsup2 d⁴
k2= turbulent flow constant
Pipe diameter Flow seems to be turbulent as both the materials (B2+ H2O) are not viscous
D =39Q ⁰ ⁴⁵ ρ sup1sup3⁰
Q =52 + 572 = 1092msup3hr = 303 x 10macrsup3msup3s= 38564 ftsup3hr
Ρ = 926328 kgmsup3 =57828 lbftsup3
D =39 x Q ⁰ ⁴⁵ x ρ sup1sup3⁰
D =39 x (38564) ⁰ ⁴⁵ x (57828) sup1sup3⁰ 3600
D= 24 inch = 25 inch = 00635m
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Velocity(v)
V =4 Q proddsup2
= 303 x 10macrsup3 msup3s x 4 314 x (00635)sup2
= 0957 ms (approx 1ms)
Reynoldrsquosnumber(Re)
Re = dvρ Μ = 00635 x 1 x 926328 0572
Re =103 x 10⁵
Thus the flow is highly turbulent
Flow regime Reynoldrsquos no(Re)
No of element No of elements to add if viscosity ratio between fluids exceeds 10001
No of elements to add if volumetric ratio between fluids exceeds 1001
Laminar lt1 24 6 61-10 18 6 611-50 14 6 651-100 12 6 6101-500 10 6 6
Transitional 501-1000 8 4 41001-2000 6 4 4
Turbulent 2001-5000 4 2 25001+ 2 2 2
Thus from the above table the mixer will have 2 elements
The mixer length will be based on the number of elements required An approximate length can be determined by multiplying the number of elements by 15
Mixer length = 15 x 2 =3
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For turbulent flow applications it is generally recommended that a minimum velocity of 10 ftsec be maintained
V= 0408 x QDsup2 = 0408 x 4813sup2 = 218 ftsec =066 ms
DECANTER DESIGN
Benzene Water
Flow rate (msup3h) 52 572
Flow rate (kgh) 4543812 570311
Density (kgmsup3) 87381 99704
Viscosity (Pas) 0000604 000089
Take Dd = 150microm
microd = (150 Х 10ˉ⁶)sup2 Х 981 Х (87381-99704) 18 Х 000089
microd = -169787 Х 10ˉsup3 ms = -17 mms (rising)
As the flow rate is small we will use a vertical cylindrical vessel
The decanter vessel is sized on the basis that the velocity of the continuous phase must be less than settling velocity of the droplets of the dispersed phase Plug flow is assumed and the velocity of the continuous phase calculated using the area of the interfacemicroc =Lclt microdAiWhere microd = settling velocity of the dispersed phase droplets msmicroc = velocity of the continuous phase msLc = continuous phase volumetric flow rate msup3sAi = area of the interface msup2
29 of 72
Lc = 570311 X 1 99704 3600
= 00015889 msup3s
Ai=Lc = 00015889 microc 00017
= 0935817588 msup2
For a vertical cylindrical decanterAi = prodrsup2
r = 0935817588 prodr = 0545835318 m
Diameter= 1091670637 m
Taking the height as twice the diameter a reasonable value for a cylinder
Height = 2183341274 m
The position of the interface should be such that the band of droplets that collect at the interface waiting to coalesce and cross the interface does not extend to the bottom (or top) of the vessel The depth of the dispersion band is a function of the liquid flow rate and the interfacial area A value of to per cent of the decanter height is usually taken for the design purposes
Take the dispersion band as 10 per cent of the height = 021833mThe residence time of the droplets in the dispersion band = 021833 = 021833microd 00017 =1285926 s (approx 2 min)
This is satisfactory time a time of 2 to 5 min is normally recommended Thus the size of the water (continuous heavy phase) droplets that could be entrained with benzene (light phase) will be
Velocity of benzene phase = 4543812 X 1 X 1 873811 3600093581
=0001543511 ms =1543511mms
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So from equation ( ) So the entrained droplet size will be =00015435 X 18 X 0000604 frac12 981 X (99704-873812)
=00001178 m=1178 microm
which is satisfactory below 150 microm
Piping arrangement
To minimize entrainment by the jet of liquid entering the vessel the inlet velocity for a decanter should keep below 1 ms
The velocity from static mixer= 066 ms
Flow rate= 4543812 + 570311 X 1 87381 99704 3600
= 0003033345msup3s
Area of pipe= flow ratevelocity
= 0003033345066
= 0004554572msup2
Pipe diameter =0004554572 x 4prod
= 0076158749 m =29983 inch (approx 3 in)
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PROJECT II
CALULATING THE DEW POINT
This project is about the study and evaluation of the performance of the compressors in the Hydrobon section of the LAB plant which is installed to optimize the purity of hydrogen coming from the product separators The compressors in this section include recycle gas compressor and make-up gas compressorThe purity of hydrogen can be increased upto 90
This project will give the company an overall view of this loop The plant is running well about its installed capacity(131-140) The company wants to retain the purity level of nearly 90 for hydrogen even after operating above installed capacity Hence the current project will give the company an idea of the current hydrogen quality(purity) which is obtained and give an idea about changes if any to be made to existing process set-up
HYDROBON REACTOR
Hydrobon reactor is designed to remove contaminants present in the raw kerosene without changing the boiling range The hydrocarbon is passed through a 2 bed reactor feed with S 12 catalyst through a feed effluent exchanger and charge heater which maintain the required reaction temperature(310 c) The reaction required hydrogen gas which is supplied from pacol net gas generated from back end and tattoray hydrogen from PX plantThe reaction charge is heated to the reaction temperature in the charge heater enters the reactor from the top and is distributed over the catalyst bed Catalytic hydrogenation takes place in the reactor The impurities react with hydrogen and form salts which are subsequently separated and finally removed in sour water stripper The reactor effluents after separation is fed to the product stripper to remove lighters and hydrotreated kerosene is fed to molex unit The sulfur and nitrogen levels are reduced to 1 ppm or less
PARAMETERS DESIGN ACTUALPlant load() 100 115Hydrobon feed rate(mthr) 58 60Temperature 416 310Pressure (kgcm2 g) 822 62H2HC ratio 385 460Recycle hydrogen purity(mole)
75 min 95
Hydrobon feed specificationa Bromine
index(mg100gm)800 800
38 of 72
b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
39 of 72
HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
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4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
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FLOW DIAGRAM OF HYDROBON SECTION
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Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
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nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
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Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
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DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
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ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
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Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
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Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
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Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
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=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
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Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
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Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
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Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
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Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
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Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
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Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
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WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
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Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
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Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
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Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
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Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
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FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
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Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
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Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
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Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
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CALCULATIONS
STATIC MIXER DESIGN
Required data
1 Physical properties of materials Density kgmsup3
Viscosity Pas = 0001Cp
2 Pressure drop Pressure drop in static mixer is best described by comparison with pipe flow
3 Geometrical parameters Diameter m
Type of static mixer constant (k)
Length (l) m
4 Process variables
Flow rate msup3s TemperaturedegC Pressure bar
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Pressure drop calculation
a) Velocity (v)
V = Qπ4 Dsup2
b) Reynoldsrsquos number(Re)
Re= dvρμ
c) Pressure drop (Δp)For Re lt50 Δp =k1x μ x l xQd dsup3
k1= laminar flow constant
For Re gt10sup3 Δp =k2 x ρ x l x vsup2d 2
= k2 x Q x l x 8 x Qsup2d prodsup2 d⁴
k2= turbulent flow constant
Pipe diameter Flow seems to be turbulent as both the materials (B2+ H2O) are not viscous
D =39Q ⁰ ⁴⁵ ρ sup1sup3⁰
Q =52 + 572 = 1092msup3hr = 303 x 10macrsup3msup3s= 38564 ftsup3hr
Ρ = 926328 kgmsup3 =57828 lbftsup3
D =39 x Q ⁰ ⁴⁵ x ρ sup1sup3⁰
D =39 x (38564) ⁰ ⁴⁵ x (57828) sup1sup3⁰ 3600
D= 24 inch = 25 inch = 00635m
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Velocity(v)
V =4 Q proddsup2
= 303 x 10macrsup3 msup3s x 4 314 x (00635)sup2
= 0957 ms (approx 1ms)
Reynoldrsquosnumber(Re)
Re = dvρ Μ = 00635 x 1 x 926328 0572
Re =103 x 10⁵
Thus the flow is highly turbulent
Flow regime Reynoldrsquos no(Re)
No of element No of elements to add if viscosity ratio between fluids exceeds 10001
No of elements to add if volumetric ratio between fluids exceeds 1001
Laminar lt1 24 6 61-10 18 6 611-50 14 6 651-100 12 6 6101-500 10 6 6
Transitional 501-1000 8 4 41001-2000 6 4 4
Turbulent 2001-5000 4 2 25001+ 2 2 2
Thus from the above table the mixer will have 2 elements
The mixer length will be based on the number of elements required An approximate length can be determined by multiplying the number of elements by 15
Mixer length = 15 x 2 =3
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For turbulent flow applications it is generally recommended that a minimum velocity of 10 ftsec be maintained
V= 0408 x QDsup2 = 0408 x 4813sup2 = 218 ftsec =066 ms
DECANTER DESIGN
Benzene Water
Flow rate (msup3h) 52 572
Flow rate (kgh) 4543812 570311
Density (kgmsup3) 87381 99704
Viscosity (Pas) 0000604 000089
Take Dd = 150microm
microd = (150 Х 10ˉ⁶)sup2 Х 981 Х (87381-99704) 18 Х 000089
microd = -169787 Х 10ˉsup3 ms = -17 mms (rising)
As the flow rate is small we will use a vertical cylindrical vessel
The decanter vessel is sized on the basis that the velocity of the continuous phase must be less than settling velocity of the droplets of the dispersed phase Plug flow is assumed and the velocity of the continuous phase calculated using the area of the interfacemicroc =Lclt microdAiWhere microd = settling velocity of the dispersed phase droplets msmicroc = velocity of the continuous phase msLc = continuous phase volumetric flow rate msup3sAi = area of the interface msup2
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Lc = 570311 X 1 99704 3600
= 00015889 msup3s
Ai=Lc = 00015889 microc 00017
= 0935817588 msup2
For a vertical cylindrical decanterAi = prodrsup2
r = 0935817588 prodr = 0545835318 m
Diameter= 1091670637 m
Taking the height as twice the diameter a reasonable value for a cylinder
Height = 2183341274 m
The position of the interface should be such that the band of droplets that collect at the interface waiting to coalesce and cross the interface does not extend to the bottom (or top) of the vessel The depth of the dispersion band is a function of the liquid flow rate and the interfacial area A value of to per cent of the decanter height is usually taken for the design purposes
Take the dispersion band as 10 per cent of the height = 021833mThe residence time of the droplets in the dispersion band = 021833 = 021833microd 00017 =1285926 s (approx 2 min)
This is satisfactory time a time of 2 to 5 min is normally recommended Thus the size of the water (continuous heavy phase) droplets that could be entrained with benzene (light phase) will be
Velocity of benzene phase = 4543812 X 1 X 1 873811 3600093581
=0001543511 ms =1543511mms
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So from equation ( ) So the entrained droplet size will be =00015435 X 18 X 0000604 frac12 981 X (99704-873812)
=00001178 m=1178 microm
which is satisfactory below 150 microm
Piping arrangement
To minimize entrainment by the jet of liquid entering the vessel the inlet velocity for a decanter should keep below 1 ms
The velocity from static mixer= 066 ms
Flow rate= 4543812 + 570311 X 1 87381 99704 3600
= 0003033345msup3s
Area of pipe= flow ratevelocity
= 0003033345066
= 0004554572msup2
Pipe diameter =0004554572 x 4prod
= 0076158749 m =29983 inch (approx 3 in)
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PROJECT II
CALULATING THE DEW POINT
This project is about the study and evaluation of the performance of the compressors in the Hydrobon section of the LAB plant which is installed to optimize the purity of hydrogen coming from the product separators The compressors in this section include recycle gas compressor and make-up gas compressorThe purity of hydrogen can be increased upto 90
This project will give the company an overall view of this loop The plant is running well about its installed capacity(131-140) The company wants to retain the purity level of nearly 90 for hydrogen even after operating above installed capacity Hence the current project will give the company an idea of the current hydrogen quality(purity) which is obtained and give an idea about changes if any to be made to existing process set-up
HYDROBON REACTOR
Hydrobon reactor is designed to remove contaminants present in the raw kerosene without changing the boiling range The hydrocarbon is passed through a 2 bed reactor feed with S 12 catalyst through a feed effluent exchanger and charge heater which maintain the required reaction temperature(310 c) The reaction required hydrogen gas which is supplied from pacol net gas generated from back end and tattoray hydrogen from PX plantThe reaction charge is heated to the reaction temperature in the charge heater enters the reactor from the top and is distributed over the catalyst bed Catalytic hydrogenation takes place in the reactor The impurities react with hydrogen and form salts which are subsequently separated and finally removed in sour water stripper The reactor effluents after separation is fed to the product stripper to remove lighters and hydrotreated kerosene is fed to molex unit The sulfur and nitrogen levels are reduced to 1 ppm or less
PARAMETERS DESIGN ACTUALPlant load() 100 115Hydrobon feed rate(mthr) 58 60Temperature 416 310Pressure (kgcm2 g) 822 62H2HC ratio 385 460Recycle hydrogen purity(mole)
75 min 95
Hydrobon feed specificationa Bromine
index(mg100gm)800 800
38 of 72
b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
39 of 72
HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
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4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
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FLOW DIAGRAM OF HYDROBON SECTION
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Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
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nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
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Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
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DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
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ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
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Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
49 of 72
Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
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Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
51 of 72
=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
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Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
53 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
54 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
55 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
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Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
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Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
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Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
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FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
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Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
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Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
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Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
Pressure drop calculation
a) Velocity (v)
V = Qπ4 Dsup2
b) Reynoldsrsquos number(Re)
Re= dvρμ
c) Pressure drop (Δp)For Re lt50 Δp =k1x μ x l xQd dsup3
k1= laminar flow constant
For Re gt10sup3 Δp =k2 x ρ x l x vsup2d 2
= k2 x Q x l x 8 x Qsup2d prodsup2 d⁴
k2= turbulent flow constant
Pipe diameter Flow seems to be turbulent as both the materials (B2+ H2O) are not viscous
D =39Q ⁰ ⁴⁵ ρ sup1sup3⁰
Q =52 + 572 = 1092msup3hr = 303 x 10macrsup3msup3s= 38564 ftsup3hr
Ρ = 926328 kgmsup3 =57828 lbftsup3
D =39 x Q ⁰ ⁴⁵ x ρ sup1sup3⁰
D =39 x (38564) ⁰ ⁴⁵ x (57828) sup1sup3⁰ 3600
D= 24 inch = 25 inch = 00635m
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Velocity(v)
V =4 Q proddsup2
= 303 x 10macrsup3 msup3s x 4 314 x (00635)sup2
= 0957 ms (approx 1ms)
Reynoldrsquosnumber(Re)
Re = dvρ Μ = 00635 x 1 x 926328 0572
Re =103 x 10⁵
Thus the flow is highly turbulent
Flow regime Reynoldrsquos no(Re)
No of element No of elements to add if viscosity ratio between fluids exceeds 10001
No of elements to add if volumetric ratio between fluids exceeds 1001
Laminar lt1 24 6 61-10 18 6 611-50 14 6 651-100 12 6 6101-500 10 6 6
Transitional 501-1000 8 4 41001-2000 6 4 4
Turbulent 2001-5000 4 2 25001+ 2 2 2
Thus from the above table the mixer will have 2 elements
The mixer length will be based on the number of elements required An approximate length can be determined by multiplying the number of elements by 15
Mixer length = 15 x 2 =3
28 of 72
For turbulent flow applications it is generally recommended that a minimum velocity of 10 ftsec be maintained
V= 0408 x QDsup2 = 0408 x 4813sup2 = 218 ftsec =066 ms
DECANTER DESIGN
Benzene Water
Flow rate (msup3h) 52 572
Flow rate (kgh) 4543812 570311
Density (kgmsup3) 87381 99704
Viscosity (Pas) 0000604 000089
Take Dd = 150microm
microd = (150 Х 10ˉ⁶)sup2 Х 981 Х (87381-99704) 18 Х 000089
microd = -169787 Х 10ˉsup3 ms = -17 mms (rising)
As the flow rate is small we will use a vertical cylindrical vessel
The decanter vessel is sized on the basis that the velocity of the continuous phase must be less than settling velocity of the droplets of the dispersed phase Plug flow is assumed and the velocity of the continuous phase calculated using the area of the interfacemicroc =Lclt microdAiWhere microd = settling velocity of the dispersed phase droplets msmicroc = velocity of the continuous phase msLc = continuous phase volumetric flow rate msup3sAi = area of the interface msup2
29 of 72
Lc = 570311 X 1 99704 3600
= 00015889 msup3s
Ai=Lc = 00015889 microc 00017
= 0935817588 msup2
For a vertical cylindrical decanterAi = prodrsup2
r = 0935817588 prodr = 0545835318 m
Diameter= 1091670637 m
Taking the height as twice the diameter a reasonable value for a cylinder
Height = 2183341274 m
The position of the interface should be such that the band of droplets that collect at the interface waiting to coalesce and cross the interface does not extend to the bottom (or top) of the vessel The depth of the dispersion band is a function of the liquid flow rate and the interfacial area A value of to per cent of the decanter height is usually taken for the design purposes
Take the dispersion band as 10 per cent of the height = 021833mThe residence time of the droplets in the dispersion band = 021833 = 021833microd 00017 =1285926 s (approx 2 min)
This is satisfactory time a time of 2 to 5 min is normally recommended Thus the size of the water (continuous heavy phase) droplets that could be entrained with benzene (light phase) will be
Velocity of benzene phase = 4543812 X 1 X 1 873811 3600093581
=0001543511 ms =1543511mms
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So from equation ( ) So the entrained droplet size will be =00015435 X 18 X 0000604 frac12 981 X (99704-873812)
=00001178 m=1178 microm
which is satisfactory below 150 microm
Piping arrangement
To minimize entrainment by the jet of liquid entering the vessel the inlet velocity for a decanter should keep below 1 ms
The velocity from static mixer= 066 ms
Flow rate= 4543812 + 570311 X 1 87381 99704 3600
= 0003033345msup3s
Area of pipe= flow ratevelocity
= 0003033345066
= 0004554572msup2
Pipe diameter =0004554572 x 4prod
= 0076158749 m =29983 inch (approx 3 in)
31 of 72
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PROJECT II
CALULATING THE DEW POINT
This project is about the study and evaluation of the performance of the compressors in the Hydrobon section of the LAB plant which is installed to optimize the purity of hydrogen coming from the product separators The compressors in this section include recycle gas compressor and make-up gas compressorThe purity of hydrogen can be increased upto 90
This project will give the company an overall view of this loop The plant is running well about its installed capacity(131-140) The company wants to retain the purity level of nearly 90 for hydrogen even after operating above installed capacity Hence the current project will give the company an idea of the current hydrogen quality(purity) which is obtained and give an idea about changes if any to be made to existing process set-up
HYDROBON REACTOR
Hydrobon reactor is designed to remove contaminants present in the raw kerosene without changing the boiling range The hydrocarbon is passed through a 2 bed reactor feed with S 12 catalyst through a feed effluent exchanger and charge heater which maintain the required reaction temperature(310 c) The reaction required hydrogen gas which is supplied from pacol net gas generated from back end and tattoray hydrogen from PX plantThe reaction charge is heated to the reaction temperature in the charge heater enters the reactor from the top and is distributed over the catalyst bed Catalytic hydrogenation takes place in the reactor The impurities react with hydrogen and form salts which are subsequently separated and finally removed in sour water stripper The reactor effluents after separation is fed to the product stripper to remove lighters and hydrotreated kerosene is fed to molex unit The sulfur and nitrogen levels are reduced to 1 ppm or less
PARAMETERS DESIGN ACTUALPlant load() 100 115Hydrobon feed rate(mthr) 58 60Temperature 416 310Pressure (kgcm2 g) 822 62H2HC ratio 385 460Recycle hydrogen purity(mole)
75 min 95
Hydrobon feed specificationa Bromine
index(mg100gm)800 800
38 of 72
b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
39 of 72
HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
40 of 72
4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
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FLOW DIAGRAM OF HYDROBON SECTION
42 of 72
Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
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nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
44 of 72
Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
45 of 72
DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
46 of 72
DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
47 of 72
ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
48 of 72
Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
49 of 72
Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
50 of 72
Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
51 of 72
=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
52 of 72
Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
53 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
54 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
55 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
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Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
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FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
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Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
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Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
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Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
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Velocity(v)
V =4 Q proddsup2
= 303 x 10macrsup3 msup3s x 4 314 x (00635)sup2
= 0957 ms (approx 1ms)
Reynoldrsquosnumber(Re)
Re = dvρ Μ = 00635 x 1 x 926328 0572
Re =103 x 10⁵
Thus the flow is highly turbulent
Flow regime Reynoldrsquos no(Re)
No of element No of elements to add if viscosity ratio between fluids exceeds 10001
No of elements to add if volumetric ratio between fluids exceeds 1001
Laminar lt1 24 6 61-10 18 6 611-50 14 6 651-100 12 6 6101-500 10 6 6
Transitional 501-1000 8 4 41001-2000 6 4 4
Turbulent 2001-5000 4 2 25001+ 2 2 2
Thus from the above table the mixer will have 2 elements
The mixer length will be based on the number of elements required An approximate length can be determined by multiplying the number of elements by 15
Mixer length = 15 x 2 =3
28 of 72
For turbulent flow applications it is generally recommended that a minimum velocity of 10 ftsec be maintained
V= 0408 x QDsup2 = 0408 x 4813sup2 = 218 ftsec =066 ms
DECANTER DESIGN
Benzene Water
Flow rate (msup3h) 52 572
Flow rate (kgh) 4543812 570311
Density (kgmsup3) 87381 99704
Viscosity (Pas) 0000604 000089
Take Dd = 150microm
microd = (150 Х 10ˉ⁶)sup2 Х 981 Х (87381-99704) 18 Х 000089
microd = -169787 Х 10ˉsup3 ms = -17 mms (rising)
As the flow rate is small we will use a vertical cylindrical vessel
The decanter vessel is sized on the basis that the velocity of the continuous phase must be less than settling velocity of the droplets of the dispersed phase Plug flow is assumed and the velocity of the continuous phase calculated using the area of the interfacemicroc =Lclt microdAiWhere microd = settling velocity of the dispersed phase droplets msmicroc = velocity of the continuous phase msLc = continuous phase volumetric flow rate msup3sAi = area of the interface msup2
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Lc = 570311 X 1 99704 3600
= 00015889 msup3s
Ai=Lc = 00015889 microc 00017
= 0935817588 msup2
For a vertical cylindrical decanterAi = prodrsup2
r = 0935817588 prodr = 0545835318 m
Diameter= 1091670637 m
Taking the height as twice the diameter a reasonable value for a cylinder
Height = 2183341274 m
The position of the interface should be such that the band of droplets that collect at the interface waiting to coalesce and cross the interface does not extend to the bottom (or top) of the vessel The depth of the dispersion band is a function of the liquid flow rate and the interfacial area A value of to per cent of the decanter height is usually taken for the design purposes
Take the dispersion band as 10 per cent of the height = 021833mThe residence time of the droplets in the dispersion band = 021833 = 021833microd 00017 =1285926 s (approx 2 min)
This is satisfactory time a time of 2 to 5 min is normally recommended Thus the size of the water (continuous heavy phase) droplets that could be entrained with benzene (light phase) will be
Velocity of benzene phase = 4543812 X 1 X 1 873811 3600093581
=0001543511 ms =1543511mms
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So from equation ( ) So the entrained droplet size will be =00015435 X 18 X 0000604 frac12 981 X (99704-873812)
=00001178 m=1178 microm
which is satisfactory below 150 microm
Piping arrangement
To minimize entrainment by the jet of liquid entering the vessel the inlet velocity for a decanter should keep below 1 ms
The velocity from static mixer= 066 ms
Flow rate= 4543812 + 570311 X 1 87381 99704 3600
= 0003033345msup3s
Area of pipe= flow ratevelocity
= 0003033345066
= 0004554572msup2
Pipe diameter =0004554572 x 4prod
= 0076158749 m =29983 inch (approx 3 in)
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PROJECT II
CALULATING THE DEW POINT
This project is about the study and evaluation of the performance of the compressors in the Hydrobon section of the LAB plant which is installed to optimize the purity of hydrogen coming from the product separators The compressors in this section include recycle gas compressor and make-up gas compressorThe purity of hydrogen can be increased upto 90
This project will give the company an overall view of this loop The plant is running well about its installed capacity(131-140) The company wants to retain the purity level of nearly 90 for hydrogen even after operating above installed capacity Hence the current project will give the company an idea of the current hydrogen quality(purity) which is obtained and give an idea about changes if any to be made to existing process set-up
HYDROBON REACTOR
Hydrobon reactor is designed to remove contaminants present in the raw kerosene without changing the boiling range The hydrocarbon is passed through a 2 bed reactor feed with S 12 catalyst through a feed effluent exchanger and charge heater which maintain the required reaction temperature(310 c) The reaction required hydrogen gas which is supplied from pacol net gas generated from back end and tattoray hydrogen from PX plantThe reaction charge is heated to the reaction temperature in the charge heater enters the reactor from the top and is distributed over the catalyst bed Catalytic hydrogenation takes place in the reactor The impurities react with hydrogen and form salts which are subsequently separated and finally removed in sour water stripper The reactor effluents after separation is fed to the product stripper to remove lighters and hydrotreated kerosene is fed to molex unit The sulfur and nitrogen levels are reduced to 1 ppm or less
PARAMETERS DESIGN ACTUALPlant load() 100 115Hydrobon feed rate(mthr) 58 60Temperature 416 310Pressure (kgcm2 g) 822 62H2HC ratio 385 460Recycle hydrogen purity(mole)
75 min 95
Hydrobon feed specificationa Bromine
index(mg100gm)800 800
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b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
39 of 72
HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
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4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
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FLOW DIAGRAM OF HYDROBON SECTION
42 of 72
Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
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nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
44 of 72
Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
45 of 72
DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
47 of 72
ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
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Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
49 of 72
Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
50 of 72
Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
51 of 72
=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
52 of 72
Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
53 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
54 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
55 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
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Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
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Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
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For turbulent flow applications it is generally recommended that a minimum velocity of 10 ftsec be maintained
V= 0408 x QDsup2 = 0408 x 4813sup2 = 218 ftsec =066 ms
DECANTER DESIGN
Benzene Water
Flow rate (msup3h) 52 572
Flow rate (kgh) 4543812 570311
Density (kgmsup3) 87381 99704
Viscosity (Pas) 0000604 000089
Take Dd = 150microm
microd = (150 Х 10ˉ⁶)sup2 Х 981 Х (87381-99704) 18 Х 000089
microd = -169787 Х 10ˉsup3 ms = -17 mms (rising)
As the flow rate is small we will use a vertical cylindrical vessel
The decanter vessel is sized on the basis that the velocity of the continuous phase must be less than settling velocity of the droplets of the dispersed phase Plug flow is assumed and the velocity of the continuous phase calculated using the area of the interfacemicroc =Lclt microdAiWhere microd = settling velocity of the dispersed phase droplets msmicroc = velocity of the continuous phase msLc = continuous phase volumetric flow rate msup3sAi = area of the interface msup2
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Lc = 570311 X 1 99704 3600
= 00015889 msup3s
Ai=Lc = 00015889 microc 00017
= 0935817588 msup2
For a vertical cylindrical decanterAi = prodrsup2
r = 0935817588 prodr = 0545835318 m
Diameter= 1091670637 m
Taking the height as twice the diameter a reasonable value for a cylinder
Height = 2183341274 m
The position of the interface should be such that the band of droplets that collect at the interface waiting to coalesce and cross the interface does not extend to the bottom (or top) of the vessel The depth of the dispersion band is a function of the liquid flow rate and the interfacial area A value of to per cent of the decanter height is usually taken for the design purposes
Take the dispersion band as 10 per cent of the height = 021833mThe residence time of the droplets in the dispersion band = 021833 = 021833microd 00017 =1285926 s (approx 2 min)
This is satisfactory time a time of 2 to 5 min is normally recommended Thus the size of the water (continuous heavy phase) droplets that could be entrained with benzene (light phase) will be
Velocity of benzene phase = 4543812 X 1 X 1 873811 3600093581
=0001543511 ms =1543511mms
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So from equation ( ) So the entrained droplet size will be =00015435 X 18 X 0000604 frac12 981 X (99704-873812)
=00001178 m=1178 microm
which is satisfactory below 150 microm
Piping arrangement
To minimize entrainment by the jet of liquid entering the vessel the inlet velocity for a decanter should keep below 1 ms
The velocity from static mixer= 066 ms
Flow rate= 4543812 + 570311 X 1 87381 99704 3600
= 0003033345msup3s
Area of pipe= flow ratevelocity
= 0003033345066
= 0004554572msup2
Pipe diameter =0004554572 x 4prod
= 0076158749 m =29983 inch (approx 3 in)
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PROJECT II
CALULATING THE DEW POINT
This project is about the study and evaluation of the performance of the compressors in the Hydrobon section of the LAB plant which is installed to optimize the purity of hydrogen coming from the product separators The compressors in this section include recycle gas compressor and make-up gas compressorThe purity of hydrogen can be increased upto 90
This project will give the company an overall view of this loop The plant is running well about its installed capacity(131-140) The company wants to retain the purity level of nearly 90 for hydrogen even after operating above installed capacity Hence the current project will give the company an idea of the current hydrogen quality(purity) which is obtained and give an idea about changes if any to be made to existing process set-up
HYDROBON REACTOR
Hydrobon reactor is designed to remove contaminants present in the raw kerosene without changing the boiling range The hydrocarbon is passed through a 2 bed reactor feed with S 12 catalyst through a feed effluent exchanger and charge heater which maintain the required reaction temperature(310 c) The reaction required hydrogen gas which is supplied from pacol net gas generated from back end and tattoray hydrogen from PX plantThe reaction charge is heated to the reaction temperature in the charge heater enters the reactor from the top and is distributed over the catalyst bed Catalytic hydrogenation takes place in the reactor The impurities react with hydrogen and form salts which are subsequently separated and finally removed in sour water stripper The reactor effluents after separation is fed to the product stripper to remove lighters and hydrotreated kerosene is fed to molex unit The sulfur and nitrogen levels are reduced to 1 ppm or less
PARAMETERS DESIGN ACTUALPlant load() 100 115Hydrobon feed rate(mthr) 58 60Temperature 416 310Pressure (kgcm2 g) 822 62H2HC ratio 385 460Recycle hydrogen purity(mole)
75 min 95
Hydrobon feed specificationa Bromine
index(mg100gm)800 800
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b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
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HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
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4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
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FLOW DIAGRAM OF HYDROBON SECTION
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Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
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nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
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Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
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DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
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ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
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Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
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Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
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Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
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=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
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Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
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Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
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Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
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Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
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Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
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Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
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Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
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Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
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WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
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Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
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Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
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Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
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Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
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FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
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Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
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Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
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Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
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Lc = 570311 X 1 99704 3600
= 00015889 msup3s
Ai=Lc = 00015889 microc 00017
= 0935817588 msup2
For a vertical cylindrical decanterAi = prodrsup2
r = 0935817588 prodr = 0545835318 m
Diameter= 1091670637 m
Taking the height as twice the diameter a reasonable value for a cylinder
Height = 2183341274 m
The position of the interface should be such that the band of droplets that collect at the interface waiting to coalesce and cross the interface does not extend to the bottom (or top) of the vessel The depth of the dispersion band is a function of the liquid flow rate and the interfacial area A value of to per cent of the decanter height is usually taken for the design purposes
Take the dispersion band as 10 per cent of the height = 021833mThe residence time of the droplets in the dispersion band = 021833 = 021833microd 00017 =1285926 s (approx 2 min)
This is satisfactory time a time of 2 to 5 min is normally recommended Thus the size of the water (continuous heavy phase) droplets that could be entrained with benzene (light phase) will be
Velocity of benzene phase = 4543812 X 1 X 1 873811 3600093581
=0001543511 ms =1543511mms
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So from equation ( ) So the entrained droplet size will be =00015435 X 18 X 0000604 frac12 981 X (99704-873812)
=00001178 m=1178 microm
which is satisfactory below 150 microm
Piping arrangement
To minimize entrainment by the jet of liquid entering the vessel the inlet velocity for a decanter should keep below 1 ms
The velocity from static mixer= 066 ms
Flow rate= 4543812 + 570311 X 1 87381 99704 3600
= 0003033345msup3s
Area of pipe= flow ratevelocity
= 0003033345066
= 0004554572msup2
Pipe diameter =0004554572 x 4prod
= 0076158749 m =29983 inch (approx 3 in)
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PROJECT II
CALULATING THE DEW POINT
This project is about the study and evaluation of the performance of the compressors in the Hydrobon section of the LAB plant which is installed to optimize the purity of hydrogen coming from the product separators The compressors in this section include recycle gas compressor and make-up gas compressorThe purity of hydrogen can be increased upto 90
This project will give the company an overall view of this loop The plant is running well about its installed capacity(131-140) The company wants to retain the purity level of nearly 90 for hydrogen even after operating above installed capacity Hence the current project will give the company an idea of the current hydrogen quality(purity) which is obtained and give an idea about changes if any to be made to existing process set-up
HYDROBON REACTOR
Hydrobon reactor is designed to remove contaminants present in the raw kerosene without changing the boiling range The hydrocarbon is passed through a 2 bed reactor feed with S 12 catalyst through a feed effluent exchanger and charge heater which maintain the required reaction temperature(310 c) The reaction required hydrogen gas which is supplied from pacol net gas generated from back end and tattoray hydrogen from PX plantThe reaction charge is heated to the reaction temperature in the charge heater enters the reactor from the top and is distributed over the catalyst bed Catalytic hydrogenation takes place in the reactor The impurities react with hydrogen and form salts which are subsequently separated and finally removed in sour water stripper The reactor effluents after separation is fed to the product stripper to remove lighters and hydrotreated kerosene is fed to molex unit The sulfur and nitrogen levels are reduced to 1 ppm or less
PARAMETERS DESIGN ACTUALPlant load() 100 115Hydrobon feed rate(mthr) 58 60Temperature 416 310Pressure (kgcm2 g) 822 62H2HC ratio 385 460Recycle hydrogen purity(mole)
75 min 95
Hydrobon feed specificationa Bromine
index(mg100gm)800 800
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b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
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HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
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4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
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FLOW DIAGRAM OF HYDROBON SECTION
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Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
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nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
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Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
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DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
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ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
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Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
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Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
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Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
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=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
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Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
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Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
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Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
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Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
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Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
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Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
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WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
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Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
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Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
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Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
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Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
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FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
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Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
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Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
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Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
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So from equation ( ) So the entrained droplet size will be =00015435 X 18 X 0000604 frac12 981 X (99704-873812)
=00001178 m=1178 microm
which is satisfactory below 150 microm
Piping arrangement
To minimize entrainment by the jet of liquid entering the vessel the inlet velocity for a decanter should keep below 1 ms
The velocity from static mixer= 066 ms
Flow rate= 4543812 + 570311 X 1 87381 99704 3600
= 0003033345msup3s
Area of pipe= flow ratevelocity
= 0003033345066
= 0004554572msup2
Pipe diameter =0004554572 x 4prod
= 0076158749 m =29983 inch (approx 3 in)
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PROJECT II
CALULATING THE DEW POINT
This project is about the study and evaluation of the performance of the compressors in the Hydrobon section of the LAB plant which is installed to optimize the purity of hydrogen coming from the product separators The compressors in this section include recycle gas compressor and make-up gas compressorThe purity of hydrogen can be increased upto 90
This project will give the company an overall view of this loop The plant is running well about its installed capacity(131-140) The company wants to retain the purity level of nearly 90 for hydrogen even after operating above installed capacity Hence the current project will give the company an idea of the current hydrogen quality(purity) which is obtained and give an idea about changes if any to be made to existing process set-up
HYDROBON REACTOR
Hydrobon reactor is designed to remove contaminants present in the raw kerosene without changing the boiling range The hydrocarbon is passed through a 2 bed reactor feed with S 12 catalyst through a feed effluent exchanger and charge heater which maintain the required reaction temperature(310 c) The reaction required hydrogen gas which is supplied from pacol net gas generated from back end and tattoray hydrogen from PX plantThe reaction charge is heated to the reaction temperature in the charge heater enters the reactor from the top and is distributed over the catalyst bed Catalytic hydrogenation takes place in the reactor The impurities react with hydrogen and form salts which are subsequently separated and finally removed in sour water stripper The reactor effluents after separation is fed to the product stripper to remove lighters and hydrotreated kerosene is fed to molex unit The sulfur and nitrogen levels are reduced to 1 ppm or less
PARAMETERS DESIGN ACTUALPlant load() 100 115Hydrobon feed rate(mthr) 58 60Temperature 416 310Pressure (kgcm2 g) 822 62H2HC ratio 385 460Recycle hydrogen purity(mole)
75 min 95
Hydrobon feed specificationa Bromine
index(mg100gm)800 800
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b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
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HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
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4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
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FLOW DIAGRAM OF HYDROBON SECTION
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Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
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nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
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Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
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DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
47 of 72
ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
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Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
49 of 72
Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
50 of 72
Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
51 of 72
=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
52 of 72
Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
53 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
54 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
55 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
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Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
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Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
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FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
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Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
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Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
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Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
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PROJECT II
CALULATING THE DEW POINT
This project is about the study and evaluation of the performance of the compressors in the Hydrobon section of the LAB plant which is installed to optimize the purity of hydrogen coming from the product separators The compressors in this section include recycle gas compressor and make-up gas compressorThe purity of hydrogen can be increased upto 90
This project will give the company an overall view of this loop The plant is running well about its installed capacity(131-140) The company wants to retain the purity level of nearly 90 for hydrogen even after operating above installed capacity Hence the current project will give the company an idea of the current hydrogen quality(purity) which is obtained and give an idea about changes if any to be made to existing process set-up
HYDROBON REACTOR
Hydrobon reactor is designed to remove contaminants present in the raw kerosene without changing the boiling range The hydrocarbon is passed through a 2 bed reactor feed with S 12 catalyst through a feed effluent exchanger and charge heater which maintain the required reaction temperature(310 c) The reaction required hydrogen gas which is supplied from pacol net gas generated from back end and tattoray hydrogen from PX plantThe reaction charge is heated to the reaction temperature in the charge heater enters the reactor from the top and is distributed over the catalyst bed Catalytic hydrogenation takes place in the reactor The impurities react with hydrogen and form salts which are subsequently separated and finally removed in sour water stripper The reactor effluents after separation is fed to the product stripper to remove lighters and hydrotreated kerosene is fed to molex unit The sulfur and nitrogen levels are reduced to 1 ppm or less
PARAMETERS DESIGN ACTUALPlant load() 100 115Hydrobon feed rate(mthr) 58 60Temperature 416 310Pressure (kgcm2 g) 822 62H2HC ratio 385 460Recycle hydrogen purity(mole)
75 min 95
Hydrobon feed specificationa Bromine
index(mg100gm)800 800
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b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
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HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
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4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
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FLOW DIAGRAM OF HYDROBON SECTION
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Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
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nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
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Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
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DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
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ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
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Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
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Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
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Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
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=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
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Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
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Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
54 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
55 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
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Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
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Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
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Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
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FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
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Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
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PROJECT II
CALULATING THE DEW POINT
This project is about the study and evaluation of the performance of the compressors in the Hydrobon section of the LAB plant which is installed to optimize the purity of hydrogen coming from the product separators The compressors in this section include recycle gas compressor and make-up gas compressorThe purity of hydrogen can be increased upto 90
This project will give the company an overall view of this loop The plant is running well about its installed capacity(131-140) The company wants to retain the purity level of nearly 90 for hydrogen even after operating above installed capacity Hence the current project will give the company an idea of the current hydrogen quality(purity) which is obtained and give an idea about changes if any to be made to existing process set-up
HYDROBON REACTOR
Hydrobon reactor is designed to remove contaminants present in the raw kerosene without changing the boiling range The hydrocarbon is passed through a 2 bed reactor feed with S 12 catalyst through a feed effluent exchanger and charge heater which maintain the required reaction temperature(310 c) The reaction required hydrogen gas which is supplied from pacol net gas generated from back end and tattoray hydrogen from PX plantThe reaction charge is heated to the reaction temperature in the charge heater enters the reactor from the top and is distributed over the catalyst bed Catalytic hydrogenation takes place in the reactor The impurities react with hydrogen and form salts which are subsequently separated and finally removed in sour water stripper The reactor effluents after separation is fed to the product stripper to remove lighters and hydrotreated kerosene is fed to molex unit The sulfur and nitrogen levels are reduced to 1 ppm or less
PARAMETERS DESIGN ACTUALPlant load() 100 115Hydrobon feed rate(mthr) 58 60Temperature 416 310Pressure (kgcm2 g) 822 62H2HC ratio 385 460Recycle hydrogen purity(mole)
75 min 95
Hydrobon feed specificationa Bromine
index(mg100gm)800 800
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b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
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HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
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4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
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FLOW DIAGRAM OF HYDROBON SECTION
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Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
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nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
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Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
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DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
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ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
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Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
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Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
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Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
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=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
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Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
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Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
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Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
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Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
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Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
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Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
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Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
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Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
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Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
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Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
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Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
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WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
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Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
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Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
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Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
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Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
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FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
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Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
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Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
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Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
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PROJECT II
CALULATING THE DEW POINT
This project is about the study and evaluation of the performance of the compressors in the Hydrobon section of the LAB plant which is installed to optimize the purity of hydrogen coming from the product separators The compressors in this section include recycle gas compressor and make-up gas compressorThe purity of hydrogen can be increased upto 90
This project will give the company an overall view of this loop The plant is running well about its installed capacity(131-140) The company wants to retain the purity level of nearly 90 for hydrogen even after operating above installed capacity Hence the current project will give the company an idea of the current hydrogen quality(purity) which is obtained and give an idea about changes if any to be made to existing process set-up
HYDROBON REACTOR
Hydrobon reactor is designed to remove contaminants present in the raw kerosene without changing the boiling range The hydrocarbon is passed through a 2 bed reactor feed with S 12 catalyst through a feed effluent exchanger and charge heater which maintain the required reaction temperature(310 c) The reaction required hydrogen gas which is supplied from pacol net gas generated from back end and tattoray hydrogen from PX plantThe reaction charge is heated to the reaction temperature in the charge heater enters the reactor from the top and is distributed over the catalyst bed Catalytic hydrogenation takes place in the reactor The impurities react with hydrogen and form salts which are subsequently separated and finally removed in sour water stripper The reactor effluents after separation is fed to the product stripper to remove lighters and hydrotreated kerosene is fed to molex unit The sulfur and nitrogen levels are reduced to 1 ppm or less
PARAMETERS DESIGN ACTUALPlant load() 100 115Hydrobon feed rate(mthr) 58 60Temperature 416 310Pressure (kgcm2 g) 822 62H2HC ratio 385 460Recycle hydrogen purity(mole)
75 min 95
Hydrobon feed specificationa Bromine
index(mg100gm)800 800
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b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
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HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
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4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
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FLOW DIAGRAM OF HYDROBON SECTION
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Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
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nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
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Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
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DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
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ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
48 of 72
Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
49 of 72
Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
50 of 72
Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
51 of 72
=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
52 of 72
Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
53 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
54 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
55 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
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Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
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FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
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Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
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Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
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Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
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PROJECT II
CALULATING THE DEW POINT
This project is about the study and evaluation of the performance of the compressors in the Hydrobon section of the LAB plant which is installed to optimize the purity of hydrogen coming from the product separators The compressors in this section include recycle gas compressor and make-up gas compressorThe purity of hydrogen can be increased upto 90
This project will give the company an overall view of this loop The plant is running well about its installed capacity(131-140) The company wants to retain the purity level of nearly 90 for hydrogen even after operating above installed capacity Hence the current project will give the company an idea of the current hydrogen quality(purity) which is obtained and give an idea about changes if any to be made to existing process set-up
HYDROBON REACTOR
Hydrobon reactor is designed to remove contaminants present in the raw kerosene without changing the boiling range The hydrocarbon is passed through a 2 bed reactor feed with S 12 catalyst through a feed effluent exchanger and charge heater which maintain the required reaction temperature(310 c) The reaction required hydrogen gas which is supplied from pacol net gas generated from back end and tattoray hydrogen from PX plantThe reaction charge is heated to the reaction temperature in the charge heater enters the reactor from the top and is distributed over the catalyst bed Catalytic hydrogenation takes place in the reactor The impurities react with hydrogen and form salts which are subsequently separated and finally removed in sour water stripper The reactor effluents after separation is fed to the product stripper to remove lighters and hydrotreated kerosene is fed to molex unit The sulfur and nitrogen levels are reduced to 1 ppm or less
PARAMETERS DESIGN ACTUALPlant load() 100 115Hydrobon feed rate(mthr) 58 60Temperature 416 310Pressure (kgcm2 g) 822 62H2HC ratio 385 460Recycle hydrogen purity(mole)
75 min 95
Hydrobon feed specificationa Bromine
index(mg100gm)800 800
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b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
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HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
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4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
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FLOW DIAGRAM OF HYDROBON SECTION
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Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
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nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
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Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
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DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
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ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
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Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
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Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
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Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
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=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
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Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
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Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
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Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
55 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
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Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
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Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
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Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
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Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
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Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
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WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
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Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
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FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
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Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
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Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
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Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
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PROJECT II
CALULATING THE DEW POINT
This project is about the study and evaluation of the performance of the compressors in the Hydrobon section of the LAB plant which is installed to optimize the purity of hydrogen coming from the product separators The compressors in this section include recycle gas compressor and make-up gas compressorThe purity of hydrogen can be increased upto 90
This project will give the company an overall view of this loop The plant is running well about its installed capacity(131-140) The company wants to retain the purity level of nearly 90 for hydrogen even after operating above installed capacity Hence the current project will give the company an idea of the current hydrogen quality(purity) which is obtained and give an idea about changes if any to be made to existing process set-up
HYDROBON REACTOR
Hydrobon reactor is designed to remove contaminants present in the raw kerosene without changing the boiling range The hydrocarbon is passed through a 2 bed reactor feed with S 12 catalyst through a feed effluent exchanger and charge heater which maintain the required reaction temperature(310 c) The reaction required hydrogen gas which is supplied from pacol net gas generated from back end and tattoray hydrogen from PX plantThe reaction charge is heated to the reaction temperature in the charge heater enters the reactor from the top and is distributed over the catalyst bed Catalytic hydrogenation takes place in the reactor The impurities react with hydrogen and form salts which are subsequently separated and finally removed in sour water stripper The reactor effluents after separation is fed to the product stripper to remove lighters and hydrotreated kerosene is fed to molex unit The sulfur and nitrogen levels are reduced to 1 ppm or less
PARAMETERS DESIGN ACTUALPlant load() 100 115Hydrobon feed rate(mthr) 58 60Temperature 416 310Pressure (kgcm2 g) 822 62H2HC ratio 385 460Recycle hydrogen purity(mole)
75 min 95
Hydrobon feed specificationa Bromine
index(mg100gm)800 800
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b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
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HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
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4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
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FLOW DIAGRAM OF HYDROBON SECTION
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Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
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nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
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Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
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DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
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ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
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Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
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Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
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Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
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=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
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Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
53 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
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Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
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Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
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Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
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Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
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WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
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Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
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Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
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Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
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Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
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FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
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Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
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Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
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Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
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PROJECT II
CALULATING THE DEW POINT
This project is about the study and evaluation of the performance of the compressors in the Hydrobon section of the LAB plant which is installed to optimize the purity of hydrogen coming from the product separators The compressors in this section include recycle gas compressor and make-up gas compressorThe purity of hydrogen can be increased upto 90
This project will give the company an overall view of this loop The plant is running well about its installed capacity(131-140) The company wants to retain the purity level of nearly 90 for hydrogen even after operating above installed capacity Hence the current project will give the company an idea of the current hydrogen quality(purity) which is obtained and give an idea about changes if any to be made to existing process set-up
HYDROBON REACTOR
Hydrobon reactor is designed to remove contaminants present in the raw kerosene without changing the boiling range The hydrocarbon is passed through a 2 bed reactor feed with S 12 catalyst through a feed effluent exchanger and charge heater which maintain the required reaction temperature(310 c) The reaction required hydrogen gas which is supplied from pacol net gas generated from back end and tattoray hydrogen from PX plantThe reaction charge is heated to the reaction temperature in the charge heater enters the reactor from the top and is distributed over the catalyst bed Catalytic hydrogenation takes place in the reactor The impurities react with hydrogen and form salts which are subsequently separated and finally removed in sour water stripper The reactor effluents after separation is fed to the product stripper to remove lighters and hydrotreated kerosene is fed to molex unit The sulfur and nitrogen levels are reduced to 1 ppm or less
PARAMETERS DESIGN ACTUALPlant load() 100 115Hydrobon feed rate(mthr) 58 60Temperature 416 310Pressure (kgcm2 g) 822 62H2HC ratio 385 460Recycle hydrogen purity(mole)
75 min 95
Hydrobon feed specificationa Bromine
index(mg100gm)800 800
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b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
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HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
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4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
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FLOW DIAGRAM OF HYDROBON SECTION
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Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
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nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
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Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
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DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
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ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
48 of 72
Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
49 of 72
Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
50 of 72
Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
51 of 72
=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
52 of 72
Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
53 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
54 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
55 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
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Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
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FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
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Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
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Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
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Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
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PROJECT II
CALULATING THE DEW POINT
This project is about the study and evaluation of the performance of the compressors in the Hydrobon section of the LAB plant which is installed to optimize the purity of hydrogen coming from the product separators The compressors in this section include recycle gas compressor and make-up gas compressorThe purity of hydrogen can be increased upto 90
This project will give the company an overall view of this loop The plant is running well about its installed capacity(131-140) The company wants to retain the purity level of nearly 90 for hydrogen even after operating above installed capacity Hence the current project will give the company an idea of the current hydrogen quality(purity) which is obtained and give an idea about changes if any to be made to existing process set-up
HYDROBON REACTOR
Hydrobon reactor is designed to remove contaminants present in the raw kerosene without changing the boiling range The hydrocarbon is passed through a 2 bed reactor feed with S 12 catalyst through a feed effluent exchanger and charge heater which maintain the required reaction temperature(310 c) The reaction required hydrogen gas which is supplied from pacol net gas generated from back end and tattoray hydrogen from PX plantThe reaction charge is heated to the reaction temperature in the charge heater enters the reactor from the top and is distributed over the catalyst bed Catalytic hydrogenation takes place in the reactor The impurities react with hydrogen and form salts which are subsequently separated and finally removed in sour water stripper The reactor effluents after separation is fed to the product stripper to remove lighters and hydrotreated kerosene is fed to molex unit The sulfur and nitrogen levels are reduced to 1 ppm or less
PARAMETERS DESIGN ACTUALPlant load() 100 115Hydrobon feed rate(mthr) 58 60Temperature 416 310Pressure (kgcm2 g) 822 62H2HC ratio 385 460Recycle hydrogen purity(mole)
75 min 95
Hydrobon feed specificationa Bromine
index(mg100gm)800 800
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b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
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HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
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4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
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FLOW DIAGRAM OF HYDROBON SECTION
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Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
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nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
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Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
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DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
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ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
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Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
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Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
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Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
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=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
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Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
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Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
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Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
55 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
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Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
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Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
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Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
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Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
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Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
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WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
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Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
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Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
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Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
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FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
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Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
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Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
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Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
b Nitrogen(ppm) 2 2c Sulphur(ppm) 1500 1038d Aromatics() 24 24
Hydrobon outlet specificatione Bromine
index(mg100gm)150 max 90
f Nitrogen(ppm) 05 max 01g Sulphur(ppm) 1 max 2h Aromatics() 20 20
Catalyst yield(mt of hydrocarbon feedkg catalyst)
5268
PROCESS VARIABLES
H2HC ratio
=total gas at stp per unit time h2 puritycharge rateA decrease in this ratio will led to rapid catalyst deactivationAn increase in this ratio will mean higher utility costRecycle hydrogen gas purityA decrease in minimum hydrogen purity will affect h2HC ratio and partial pressure of hydrogen The purity of recycle gas should be higher than a min value of 70-80 mole to achieve the desired product quality of normal operating temp
Brief Overview
The Linear Alkyl Benzene produced from Kerosene is a useful detergent intermediates and can be readily sulfonated to give linear alkyl benzene sulfonates
The kerosene from petroleum refinery contains various amounts of naturally occurring contaminants the most important ones being organic sulfur nitrogen and metal compounds The purpose of UOP Hydrobon process is to remove sulfur and nitrogen from feed which would poison the sieve in UOP Molex process unit thus reducing the adsorbent life The catalyst used in Hydrobon reactor is S12 (Cobalt-Molybdenum Oxide on alumina)
The UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
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HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
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4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
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FLOW DIAGRAM OF HYDROBON SECTION
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Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
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nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
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Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
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DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
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ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
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Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
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Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
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Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
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=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
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Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
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Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
54 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
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Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
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Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
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WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
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Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
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Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
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Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
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Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
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FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
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Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
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Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
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Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
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HD Hydrobon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
The following reactions represent in general what is taking place inside the reactor
1) Sulfur Removal
2) Nitrogen Removal
3) Metals Removal
While mechanism of organo-metallic compound removal is not well understood it is known that metals are retained on the catalyst The limiting amount of metals the catalyst can remove is related to the amount of catalyst in the plant Once the limit is exceeded metals can be found in reactor product stream
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4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
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FLOW DIAGRAM OF HYDROBON SECTION
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Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
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nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
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Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
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DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
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ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
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Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
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Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
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Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
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=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
52 of 72
Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
53 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
54 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
55 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
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Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
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4) Oxygen Removal
5) Olefin Saturation
6) Halides Removal
7) Other Reactions
Near the end of the run to compensate for the lower catalyst activity the reactor temperatures will be relatively high With the higher temperature there will be increased tendency to hydrocrack the feed which will be evident from more H2 consumption and more net stripper overhead liquid production
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FLOW DIAGRAM OF HYDROBON SECTION
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Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
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nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
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Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
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DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
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ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
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Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
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Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
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Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
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=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
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Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
53 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
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Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
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Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
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Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
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Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
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WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
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Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
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Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
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Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
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Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
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FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
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Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
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Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
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Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
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FLOW DIAGRAM OF HYDROBON SECTION
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Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
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nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
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Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
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DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
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ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
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Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
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Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
50 of 72
Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
51 of 72
=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
52 of 72
Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
53 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
54 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
55 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
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Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
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Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
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Process DescriptionThe UOP Hydrobon process is a catalytic hydrogenation method for upgrading the feed quality by removing sulfur and nitrogen without greatly changing its boiling range In addition to this metal compounds and Aromatics are also reduced in Hydrobon reactor This upgrading often-called Hydrotreating is done by passing the feedstock over a fixed bed of UOP Hydrobon catalyst
HD Unibon Process unit in LAB Front End consist of a high-pressure reactor section and a lower pressure product stripper section
(A)Reactor SectionHeart Cut Kerosene from Prefractionation Section is sent to Hydrobon feed surge drum (FA601) This stream consists of C10-C14 range of hydrocarbons which include normal paraffins non-normal paraffins and various contaminants like organic sulfur nitrogen etc The reactor charge pumps (GA601 ABC) pumps Kerosene to combine feed exchanger (EA602) The charge pumps used in Hydrobon are Sundyne pumps capable of pumping feed to high pressure of around 95-100kgcm2g
New reactor charge pump is being installed in the unit as a part of energy conservation drive However this PHA study excludes this pump operation
Before entering the combined feed exchanger Kerosene is mixed with recycle Hydrogen from Recycle Gas Compressor (GB601) A single stage double acting reciprocating compressor (GB601) is used to raise the pressure of gas The recycle gas also acts a medium for quenching the heat of reaction from the reactor in case of loss of liquid charge to the reactor
The reactor charge and recycle hydrogen gas are preheated by the reactor effluent in combine feed exchanger which is a series of shell and tube heat exchangers In CFE combined feed is preheated to 294degC and then enters the reactor charge heater (BA601) The reactor charge is heated to reaction temperature in Charge Heater The heater is convection radiation type natural draft heater The temperature is raised upto 302-305degC in this heater The heated feed enters at the top of Hydrobon Reactor (DC601) and is evenly distributed over the top of catalyst bed by vapor liquid distributor The reactor is divided into two catalyst beds separated by catalyst support grids and redistributors
Due to the exothermic nature of reactions taking place in the reactor (due to aromatic saturation and partly due to thermal hydrocracking of long molecules) the temperature of outlet stream leaving is higher than the reactor inlet stream temperature The heat of reaction as well as a large portion of the heat contained in the reactor feed is recovered in combine feed exchangers (EA602) Final cooling of the reactor effluent is obtained by passing it through air-cooled fin-fan exchanger (EC601) DM water is injected into the reactor effluent before it enters EC601 in order to prevent the deposition of salts that can corrode and foul the coolers The sulfur and
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nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
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Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
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DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
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ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
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Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
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Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
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Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
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=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
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Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
53 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
54 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
55 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
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Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
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Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
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WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
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Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
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Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
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Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
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Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
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FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
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Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
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Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
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nitrogen contained in the feed is converted to hydrogen sulfide (H2S) and ammonia (NH3) in the reactor these two reaction products combine to form ammonium salts that can solidify and precipitate as the reactor effluent is cooled Hence DM water is added to reactor effluent to dissolve these salts before they precipitate
To maintain the reaction loop pressure and to makeup for the hydrogen consumed in the reaction make up Hydrogen is added to reactor loop before it enters the cooler EC601 This make up gas is supplied by four stage double acting reciprocating make up compressor (GB602) The addition of this Hydrogen before cooler also serves the purpose of removal of after-cooler in the 4 th stage of compressor (GB602) The make up hydrogen is obtained from LAB PACOL process at 23kgcm2g which enters the 1st stage of make up gas compressor The balance hydrogen is obtained from Tatoray Unit from PG-PX at 135kgcm2g and LPFD gas that enter the 3rd stage suction of compressor
The reactor effluent is cooled to about 60degC using air-cooled fin-fan heat exchangers (EC601) Cooled effluent enters the high-pressure separator (FA602) where the hydrocarbon water and gas phases disengage and are removed individually A circumferential mesh blanket is placed in the separator to help separate water from hydrocarbon The water collected in a boot attached to separator is removed on level control and sent to a sour water-degassing drum (FA606) This water contains high concentration of toxic gases H2S and NH3
The hydrogen rich gas leaving the top of separator is sent to recycle gas compressor section through recycle compressor suction drum The H2S content in the recycle gas is controlled by a slip streamvent provided above the Product Separator (connected to FA605 Off Gas line) This venting is to be done when the H2S in recycle gas crosses 10 by volume
(B) Fractionation SectionThe hydrocarbon liquid collected in separator FA602 is sent to the low-pressure flash drum (FA603) where additional hydrogen and other dissolved gases are removed from top A part of this gas is burnt in the heater and the remaining part is used as makeup gas
LPFD bottom is sent to the product stripper (DA601) on level control The product stripper strips out the water light ends and H2S in the separator liquid The overhead vapors are condensed in an air-cooled fin fan condenser (EC602) enters the overhead receiver (FA605) The water collected in the receiver boot is sent to the sour water stripper unit Condensed hydrocarbon is refluxed back to the column and a net overhead liquid draw is removed for further processing in light end stripper column (DA603) The non-condensable gases leave the overhead receiver on pressure control and are normally routed to fuel gas system through FA 802 The contaminant free material from column bottom is first exchanged with PACOL Stripper feed and then with product stripper feed and sent to Molex unit on level control A slipstream is bypassed around the stripper feedbottom exchanger on TRC control to ensure a constant feed temperature to
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Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
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DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
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ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
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Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
49 of 72
Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
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Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
51 of 72
=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
52 of 72
Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
53 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
54 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
55 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
Molex Unit Molex feed temperature is to be constantly monitored to prevent ingress of unsaturates into Molex Unit
The Light End Stripper bottom liquid is routed to either return Kerosene or to PX as a fuel Purpose of Light End Stripper is to stabilize the lights stream of dissolved gases Light End Stripper bottom temperature is a significant parameter It is to be maintained above 160degC to prevent H2S carryover to storage tank
(C)Sour Water Stripping Section The water collected in Product Separator (FA602) and other sections contains large concentration of toxic gases like H2S and NH3 Hence the water from boot is diverted to sour water degassing drum (FA606) which removes dissolved gases at lower pressure of 10kscg Bottom liquid is fed to sour water stripping column (DA602) The H2S and NH3 stripped water from sour water stripping column is then drained to sewer system The off gases which contain H2S and NH3 are burnt in heater as off gas Sour Water Stripper bottoms are analyzed for pH and H2S once in a week
Reciprocating compressor
A reciprocating compressor or a piston compressor is a positive-displacement compressor that consists of a piston driven by a crankshaft to deliver gases at high pressure The intake gas enters a suction manifold then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft and the gas is then discharged
The reciprocating air compressor is said to be double acting when the compression is accomplished using only both sides of the piston
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DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
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ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
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Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
49 of 72
Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
50 of 72
Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
51 of 72
=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
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Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
53 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
54 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
55 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
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Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
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Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
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FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
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Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
DEMISTER PAD
A demister is a device often fitted to vapor liquid separator vessels to enhance the removal of liquid droplets entrained in a vapor stream Demisters may be a mesh type or vane pack or other structure intended to aggregate the mist into droplets that are heavy enough to separate from the vapor stream
Demisters can reduce the residence time required to separate a given liquid droplet size thereby reducing the volume and associated cost of separator equipment
Demisters are often used where vapor quality is important in regard to entrained liquids particularly where separator equipment costs are high or where space or weight savings are advantageous
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DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
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ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
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Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
49 of 72
Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
50 of 72
Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
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=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
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Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
53 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
54 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
55 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
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Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
DEW POINT
When a liquid mixture is heated from a sub-cooled state at constant pressurethe vaporization occurs over a range of temperatures unlike vaporization of a pure substance which occurs at a constant temperature at a given pressure For any mixtures the two limiting temperatures of the above range are known as bubble point and dew point
Figure shows T vs x y of n-pentane for the n-pentanen-hexane system at 101325kPa(760 torr) considering the mixture to be an ideal one
As the heating process continues beyond M the temperature rises the amount of vapour increases and the amount of liquid decreases During this process the vapor and liquid phase composition change along the paths MrsquoN and MNrsquo respectively Finally as the point N is approached the liquid phase is reduced to minute drops( called dew) and at point N the liquid phase is completely vaporized to a saturated vapour phase Hence the point N is called the dew point
For an ideal mixture the dew point can be calculated using the Raoultrsquos law For a given pressure and composition the dew point and the composition at respective points are calculated by the iterative calculations as shown below
Dew point
i For a vapor mixture of known composition assume a temperature and find the vapor pressure of all the components pis at this temperature
ii Calculate xi=yippisiii Σ xi should be 1 If xi ne 1 then a new temperature should be assumed and the above
calculations be repeatediv The temperature for which xi=1 is the dew point and the liquid composition at dew point
is given by xiv Initial guess value of temperature can be taken as Ti= Σ Xi Tis
Performance evaluation of compressor GB-601 ABGB-601 AB is a one stage double acting reciprocating compressor
1 First Stage Calculation
The following are the 1st stage condition for the calculation
Suction temperature = 58degC =331 KSuction pressure = 60 kgcmsup2a =5883 barDischarge temperature = 83degC = 356 KDischarge pressure = 74 kgcmsup2a=7256 bar
47 of 72
ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
48 of 72
Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
49 of 72
Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
50 of 72
Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
51 of 72
=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
52 of 72
Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
53 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
54 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
55 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
ThusMW mix =Average molecular weight = 3713kgkmolPc of mixture = 1447 barTc of mixture = 47346degKCp of mixture = 30892
component mol wt mol mol fraction Tc Pc Cp vap A Cp vap B Cp vap C Cp vap D Cp wt MW wt Pc wt Tc wt Cpbar a KJKmolK kgkmol bar a KJkmolK
h2 2016 951 0951 33 129 2714 000927 -14E-05 765E-09 2903625 191722 122679 31383 2761347C1 16042 07 0007 1904 46 1925 005213 12E-05 -11E-08 3881457 011229 0322 13328 0271702C2 30069 22 0022 3054 488 5409 01781 -69E-05 871E-09 6041277 066152 10736 67188 1329081C3 44096 13 0013 3698 425 -4224 03063 -000016 322E-08 8599384 057325 05525 48074 111792C4 58123 05 0005 4252 38 9487 03313 -000011 -28E-09 1133625 029062 019 2126 0566813C5 7215 01 0001 4697 337 -362 03313 -000026 531E-08 8376721 007215 00337 04697 0083767C6 86178 01 0001 5083 303 -4413 0582 -000031 649E-08 16618 008618 00303 05083 016618
degK degK
At suction conditions
Pr = P suction Pc = 58831447 =4O66
48 of 72
Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
49 of 72
Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
50 of 72
Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
51 of 72
=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
52 of 72
Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
53 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
54 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
55 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
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FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
Tr = T suction Tc=3314734 =699Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4066ampTr =699Suction Compressibility =Z1 =099
At discharge conditions
Pr = P dischargePc = 72561447 =50151Tr = T discharge Tc= 3564734 =752
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 50151ampTr =752Suction Compressibility =101ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 30892 (30892 ndash 8314) =1368
Average compressibility = Z avg =(Z1 +Z2)2 = (099+101)2 = 1
Pressure ratio
PR = Pressure ratio = P dischargeP suction =725695883 =1233
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 1233k= Ratio of specific heats = 1368L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
49 of 72
Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
50 of 72
Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
51 of 72
=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
52 of 72
Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
53 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
54 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
55 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
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FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
Thus
Volumetric efficiency =097 ndash 014 [1233^(11368)-1] ndash 003 =097 ndash014[1165 -1]-003 =097- 00231 -003 =09168 =9168
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 +(22sup2 - 0065sup2))x 2 x 416 x 60= 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 09168 =332592msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
Vsp = Z x Ts x R Ps MW
WhereVsp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 1
50 of 72
Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
51 of 72
=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
52 of 72
Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
53 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
54 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
55 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
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Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
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FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
Ts = Suction temperature at 1st stage = 331degKPs = Suction pressure at 1st stage =5883 bar a= 5883101325 =5806atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =3713 kgk-mol
ThereforeV sp= (1 x 331 ) x 008206 5806 3713 = 01259msup3kg
Capacity in kghr
M =Q x Vsp =332592x01259=4187 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 331 x 1233^(1368-11368) = 331 x 10666 =350185degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
=350185-331(356-331)=0764=764
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-1
=1 x(83143713)x 331 x (13681368-1)x (1233^(1368-11368)-1)=74116 x 3717 x0057
51 of 72
=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
52 of 72
Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
53 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
54 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
55 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
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Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
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Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
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Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
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Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
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FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
=1596 Kn-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =1596kN-mkgm = Total Inlet Feed to the compressor in kghr=5864 kghrŊ ad = Adiabatic efficiency=0764
Pad(kW) = 5864 x 1596(764 x 3600)=338797 kwAdiabatic efficiency can be enhanced by maintaining Td-actual as close to Tad as possible
Nowif the adiabatic efficiency is increased to 100 ie Td-actual =Tad then
Adiabatic power required = 5864 x 1596(1 x 3600)=2599 kw
Power saved= 338797 -2599=78897 kw If the cost of the power is rs 6kw hourSavings per day= 6 x24 x78897=rs 11361168day If we consider that the plant operates for around 8040 hoursdaySavings per year =6 x 8040 x 78897=rs 380599128=rs 3805 lakhs year
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)=8314 x 331 x 1 x ln(72565883)=2751934 x209=57713 KjKmol=57713 KjKmol x 111607 kmolhr=64411 x 10^3 Kjhr=1789 kw
Polytropic Work
52 of 72
Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
53 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
54 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
55 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
Wpoly=R gas x T1x Z1 x n(n-1)x ((P2P1)sup1macrsup1n-1)=8314 x 331 x 1 x 12(12-1) x [(72565883)sup1macrsup112 -1]=2751934 x 6 x 03557=587459Kjkmol=587459 Kjkmolx 111607 kmolhr=65551 x 10^3 kmolhr=18208 Kw
PERFORMANCE EVALUATION OF GB-602
1First Stage Calculations
The following are the 1st stage conditions for our calculations
Suction Temperature = 35degC =308degKSuction Pressure =158kgcmsup2a =154 barDischarge temperature =121degC = 394degKDischarge Pressure =47kgcmsup2a =46 bar
Thus
MW mix = Average Molecular Weight = 31842Pc of Mixture=1434Tc of Mixture=43367Cp of Mixture=2992
components mol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 959 0959 332 13 2714 000927 -1E-05 765E-09 2891846 1933344 12467 318388 277328C1 16042 2 002 1904 464 1925 005213 12E-05 -11E-08 36279672 032084 0928 3808 0725593C2 30069 08 0008 3054 488 5409 01781 -7E-05 871E-09 54349686 0240552 03904 24432 0434797C3 44096 06 0006 3698 425 -4224 03063 -00002 322E-08 76528523 0264576 0255 22188 0459171C4 58123 03 0003 4252 38 9487 03313 -00001 -28E-09 10179777 0174369 0114 12756 0305393C5 7215 03 0003 4697 337 -362 03313 -00003 531E-08 758641 021645 01011 14091 0227592
NC-6 86178 0 0 5083 303 -4413 0582 -00003 649E-08 14837513 0 0 0 0h2s 34076 01 0001 3732 894 3194 000144 243E-05 -12E-08 34385107 0034076 00894 03732 0034385
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
53 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
54 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
55 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
54 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
55 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MWWhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
55 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
M= QV sp = 216568 kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts = 9523 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=1024077 k-Nm
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
56 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
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FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
= 80352 kw
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) = 8654 kw
Polytropic Work
W poly =Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=3061206803 kjkmol=3416521077 kjhr
=9490351752 kw
GB-602 2 ND STAGE
componentsmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8818 08818 332 13 2714 0009274 -1381E-05 7645E-09 2891846 1777709 114634 2927576 255002983C1 16042 187 00187 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0299985 086768 356048 067842987C2 30069 462 00462 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1389188 225456 1410948 25109555C3 44096 152 00152 3698 425 -4224 03063 -000016 322E-08 76528523 0670259 0646 562096 116323356C4 58123 133 00133 4252 38 9487 03313 -000011 -28E-09 10179777 0773036 05054 565516 135391028C5 7215 114 00114 4697 337 -362 03313 -000026 531E-08 758641 082251 038418 535458 086485074
NC-6 86178 07 0007 5083 303 -4413 0582 -0000312 6494E-08 14837513 0603246 02121 35581 103862591NC-7 100203 044 00044 5401 274 -5619 067692 -0000364 7407E-08 17192976 0440893 012056 237644 075649093NC-8 11423 019 00019 5691 249 -7477 0777471 -0000428 9176E-08 19563741 0217037 004731 108129 037171108h2s 34076 001 00001 3732 894 3194 0001436 2432E-05 -1176E-08 34385107 0003408 000894 003732 000343851
100 1 6997271 1651013 7062957 342419447
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)
57 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
58 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degK
59 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
Ps = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts =9467 Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14=124037kN-mkg
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
60 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head m = Total Inlet Feed to the compressor in kghrŊ ad = Adiabatic efficiency
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1) =7132 kw
Polytropic WorkW poly= Rgas T1Z1n(n-1)((P2P1)^(1-(1n)))-1)
=770088kw
GB-602 3 RD STAGE At suction conditions
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T c wt Cpbar KJKmolK kgkmol bar a KJkmolK
h2 2016 8436 08436 332 13 2714 0009274 -14E-05 765E-09 2891846 1700698 109668 2800752 2439561C1 16042 475 00475 1904 464 1925 005213 12E-05 -11E-08 3627967 0761995 2204 9044 1723284C2 30069 63 0063 3054 488 5409 01781 -69E-05 871E-09 5434969 1894347 30744 192402 342403C3 44096 224 00224 3698 425 -4224 03063 -000016 322E-08 7652852 098775 0952 828352 1714239C4 58123 086 00086 4252 38 9487 03313 -000011 -28E-09 1017978 0499858 03268 365672 0875461C5 7215 064 00064 4697 337 -362 03313 -000026 531E-08 758641 046176 021568 300608 048553
NC-6 86178 04 0004 5083 303 -4413 0582 -000031 649E-08 1483751 0344712 01212 20332 0593501NC-7 100203 025 00025 5401 274 -5619 067692 -000036 741E-08 1719298 0250508 00685 135025 0429824NC-8 11423 011 00011 5691 249 -7477 0777471 -000043 918E-08 1956374 0125653 002739 062601 0215201h2s 34076 004 00004 3732 894 3194 0001436 243E-05 -12E-08 3438511 001363 003576 014928 0013754
SUM 9995 09995 7040911 1799253 7539678 3387044
degK degK
Pr = P suction Pc = 4936Tr = T suction Tc= 69252
61 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
62 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
63 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given by
Ŋad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
64 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
Polytropic Work
GB-602 4 TH STAGE
componentmol wt mol molfrac Tc Pc Cp vap A Cp vapB Cp vap C Cp vap D Cp 38 C wt MW wt Pc wt T cbar KJKmolK kgkmol bar a
h2 2016 8473 08473 332 13 2714 000927 -1381E-05 7645E-09 2891846 1708157 110149 281304C1 16042 476 00476 1904 464 1925 005213 1197E-05 -1132E-08 36279672 0763599 220864 906304C2 30069 631 00631 3054 488 5409 01781 -6938E-05 8713E-09 54349686 1897354 307928 192707C3 44096 223 00223 3698 425 -4224 03063 -000016 00000000322 76528523 0983341 094775 824654C4 58123 084 00084 4252 38 9487 03313 -000011 -00000000028 10179777 0488233 03192 357168C5 7215 018 00018 4697 337 -362 03313 -000026 00000000531 758641 012987 006066 084546
NC-6 86178 031 00031 5083 303 -4413 0582 -0000312 000000006494 14837513 0267152 009393 157573NC-7 100203 014 00014 5401 274 -5619 067692 -0000364 740735E-08 17192976 0140284 003836 075614NC-8 11423 003 00003 5691 249 -7477 077747 -0000428 917635E-08 19563741 0034269 000747 017073h2s 34076 004 00004 3732 894 3194 000144 2432E-05 -1176E-08 34385107 001363 003576 014928
SUM 9953 09957 6425889 17806 717797
degK degK
At suction conditions
Pr = P suction Pc = 4936Tr = T suction Tc= 69252Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 4936 ampTr =69252Suction Compressibility =105
At discharge conditions
Pr = P dischargePc = 605Tr = T discharge Tc= 737
Thus from Nelson-Obert generalized Compressibility Charts (Annexure 11)Pr= 605 ampTr =737
65 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
Suction Compressibility =103ThusK-value of mixture =Cp mix C v mix = Cp mix (Cp mix ndash R) = 3012491 (3012491 ndash 8314) =138
Average compressibility = Z avg=(Z1 +Z2)2 = (105+103)2 = 104
Pressure ratio
PR = Pressure ratio = P dischargeP suction = 940876711 =12264
Volumetric Efficiency It is defined as the actual gas delivered to the piston displacement of the compressor
When the discharge pressure is high the quantity that is left back in space between piston and the cylinder end walls is also high
Thus volumetric efficiency of the compressor can be theoretically estimated as
Ŋ ad = 097 ndash C x [ PR ^(1k) -1] ndashL
WhereC= Clearance in for 1st stage = 14 (from design data)PR= Pressure Ratio = 12264k= Ratio of specific heats = 138L= Leakage losses normally 003 to 005 for Lubricated compressor and 0075 to 01 for non-lubricated compressor
Since GB-601 is LUBRICATED COMPRESSOR we will take L=003
Thus
Volumetric efficiency =097 ndash 014 [12264 ^(1138)-1] ndash 003 =097 ndash 014[11591 -1]-003 =097- 0022285 -003 =0917715 =91771
Piston Displacement
Piston displacement is defined as the net volume actually displaced by the piston at rated machine speed as the piston travels its length from top dead center to bottom dead center
66 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
Piston displacement = Vd(msup3hr) = (prod4) x (Dsup2+(Dsup2- dsup2))x S x N x 60
Whered= diameter of the rod =65mm=0065mS= Cylindrical Stroke = 200mm=2m D= Cylindrical Bore Diameter=220mm =22mN= Speed of Compressor =416 rpm
Therefore
Piston displacement = (314 4) x (22sup2 + (22sup2 - 0065sup2))x 2 x 416 x 60 = 0785 x (00484 + 0044175) x 4992 = 3627755msup3hr
Capacity of the compressor
Inlet capacity of the compressor = Q (msup3hr) =Vd x ŋ ad =3627755 x 0917715 =3329244msup3hr
Specific Volume
It is the inverse of gas density ie it is the volume of the gas per kilogram at specified conditions
It is given as follows
V sp = Z x Ts x R Ps MW
WhereV sp = Specific volume of Gas in msup3hrZ = Compressibility factor at first stage suction condition = 104Ts = Suction temperature at 1st stage = 328degKPs = Suction pressure at 1st stage = 7671 bar a= 7671101325 =757068atm aR = Universal gas constant = 008206msup3-atmk-moldegKMW = Molecular weight of gas at 1st stage =33809 kgk-mol
ThereforeV sp = (104 x 328 ) x 008206 75708 33809 = 010936msup3kg
67 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
Capacity in kghr
Adiabatic Discharge Temperature
When the compression takes place by adiabatic process the discharge temperature can be predicted by
Tad = Ts x (PR)^(k-1k) = 328 x 12264 ^(138-1138) = 328 x 10666 =34696degK
Adiabatic Efficiency
It indicates the actual process compressor deviation from the adiabatic compression It is given byŊad = Tad- Ts Td actual ndash Ts
Adiabatic Head It is defined as the work done by the compressor to raise the pressure of the gas It is given by
Had (kN-mkg) = Z avg x R x Ts x k x [PR^(k-1k) ndash 1] MW mix k-14
Adiabatic PowerIt is the power required by the compressor to raise the pressure of gas It is brake power in mechanical terms
Pad (kW) = m x HadŊ ad x 3600
WhereHad = Adiabatic Head =m = Total Inlet Feed to the compressor in kghr=Ŋ ad = Adiabatic efficiency=
Isothermal work
W iso = R gas x Ts x Z1 x ln(P2P1)
68 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
FLASH CALCULATION FOR GB-601 AB
Dew point calculations at 1 st stage discharge pressure of 725692kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0951 127844 23232 808 3515 1213831 186897 2575438 0036926 1526027c1 0007 13584 96813 -372 3515 1080026 4903342 67568 0001036 1526027c2 0022 138797 158218 -137622 3515 919506 9848358 1357103 0016211 1526027c3 0013 13709 18728 -251 3515 7971255 289649 0399136 003257 1526027c4 0005 139836 229244 -278623 3515 6900247 9925201 0136769 0036558 1526027c5 0001 139778 25546 -362529 3515 5874315 355781 0049027 0020397 1526027c6 0001 59951 11687 -4895 3515 2132267 8433968 0001162 0860437 1526027
Dew point of the mixture at 725692kPa is 3515k(785 c)
FLASH CALCULATION FOR GB-602 AB
Dew point calculations at 1 st stage discharge pressure of 4609 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 2259 1179149 132124 2866648 0003345c1 002 13584 96813 -372 2259 9226587 1016379 2205206 0000907c2 0008 138797 158218 -137622 2259 6421435 6148846 1334096 0005997c3 0006 13709 18728 -251 2259 4382307 8002241 0173622 0034558c4 0003 139836 229244 -278623 2259 2407824 1110976 0024104 0124458c5 0003 139778 25546 -362529 2259 0507518 1661162 0003604 0832369c6 0 59951 11687 -4895 2259 -060959 0543573 0001179 0h2s 0001 340819 145513 196437 2259 3407526 629E+14 136E+12 733E-16
Dew point of the mixture at 4609 kPa is 2259k(-471 c)
69 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
Dew point calculations at 2 nd stage discharge pressure of 11197 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0959 127844 23232 808 240 1184793 139794 1248499 0007681c1 002 13584 96813 -372 240 9486616 1318211 1177289 0001699c2 0008 138797 158218 -137622 240 6886262 9787362 0874106 0009152c3 0006 13709 18728 -251 240 4994249 1475621 0131787 0045528c4 0003 139836 229244 -278623 240 3177223 2398006 0021417 0140079c5 0003 139778 25546 -362529 240 1439707 4219461 0003768 0796097c6 0 59951 11687 -4895 240 -012215 0885018 000079 0h2s 0001 340819 145513 196437 240 340753 629E+14 562E+11 178E-15
1 1000236
Dew point of the mixture at 11197 kPa is 240k(-33 c)
Dew point calculations at 3 rd stage discharge pressure of 28236 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3006 1203178 168010 5950188 0015411c1 0016 13584 96813 -372 3006 1032299 30424 1077488 0001485c2 0035 138797 158218 -137622 3006 836376 4288792 1518909 0023043c3 0021 13709 18728 -251 3006 6911178 1003428 0355372 0059093c4 0009 139836 229244 -278623 3006 5578308 2646235 0093718 0096032c5 0002 139778 25546 -362529 3006 4313991 7473814 0026469 007556c6 0001 59951 11687 -4895 3006 1350951 3861097 0001367 0731295h2s 0001 340819 145513 196437 3006 3407548 629E+14 223E+11 449E-15
Dew point of the mixture at 28236 kPa is 3006k(276 c)
70 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
71 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
Dew point calculations at 4 th stage discharge pressure of 64262 kPa
comp mol frac yi antioine constant temp k lnPi pi ki=pipt xi=yikia b c
h2 0917 127844 23232 808 3485 1213288 185884 2892593 0031702c1 0016 13584 96813 -372 3485 1077604 47860 7447637 0002148c2 0035 138797 158218 -137622 3485 9153075 9443436 1469521 0023817c3 0021 13709 18728 -251 3485 7918029 2746353 0427368 0049138c4 0009 139836 229244 -278623 3485 6833973 9288738 0144545 0062264c5 0002 139778 25546 -362529 3485 5796459 329132 0051217 0039049c6 0001 59951 11687 -4895 3485 2093581 811392 0001263 0791997h2s 0001 340819 145513 196437 3485 3407561 629E+14 979E+10 102E-14
Dew point of the mixture at 64262 kPa is 3485k
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Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
72 of 72
Recommendations
1 As per the standard calculations a vertical vessel can be used as a decantor but it will be more efficient to use horizontal vessel as it will give more residence time for settling
2 Static mixer metallurgy should be selected as per benzene and taking in care the acidic solution formation after extraction of impurities from benzene
3 All instruments like pH meter Control valves should be reliable Their importance in this scheme should ne taken care of while purchasing
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