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Process Flow diagram
Fig : Process Flow sheet Made with help of ASPEN PLUS
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Equipment Designed
1. Compressor2. Pump
3. Reactor
4. Gas Absorber
5. Crude Fractionating Column
6. Refining Column
7. Effluent Column
8. End stripping Column
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Compressor Design Positive Displacement Reciprocating
compressor
Multi Stage.Assumptions:
- Zero clearance
Volume Swept in compressor
n = No. of cylinder Fig:- Interior of reciprocating Compressor
N = rotational speed
D = dia/bore of the cylinderL = Stroke length
[1]
PB= power consumed by compressor
Fig: Gas Compression Cycle1 References: mccabe smith unit o eration of chemical en ineerin 7th edition 7th cha ter a e 221
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Calculated Data
[1] References: COMPRESSOR HANDBOOK Paul C. Hanlon 2001 Chapter 2 compressorperformance - positive displacemnt by
The McGraw-Hill Companies
AIM : To compress the CO coming from Sub group 1 Inter Stage Cooling Assuming Temperature rise in water (T) = 20oc Coolant Used :water Power = 165.56 kw = 221 hp Fig: water cooling system No. of stage = 3 Compression ratio R(total) = 41.95 Heat load in each cooler = 49,570.834 kJ/hr Total heat load = 3*49,570.834 = 148712.50 KJ/hr Amount of water required = 1770.38 Kg/hr
Pressure Temperature Flow Rate
Inlet condition 1 atm 373 k 0.024 m3/sec
Outlet Condition 42 atm 453 k
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RPM calculation
bore/stroke ratio < 1.7. [1]
No. of Cylinders Stroke length and bore diameter Maximum Volume occupied in each
cylinders.
Table : Calculation of RPM, bore length, piston speed, volume of each cylinder[2]
References :
[1] Stroke-to-Bore Ratio: A Key to Engine Efficiency by Dr. Randy Herold Engineer General Atomics Systems[2] ''Large reciprocating Compressor Design Guide Lines''(1972) M.W Garland Frick Company, International Compressor Engineering
Conference
Design Data
RPM 720
No. of cylinder
(each stage)
2
Bore/ Stroke 1.35
Stroke 5.00
Bore 6.75
volume of each
cylinder per
revolution
24.48 cu inch
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Fig: Schematic Diagram for Pump design
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Requirements for adiabatic Pump
Specific volume = 1262 cm3/ kg
Thermal Expansion Coefficient() = 425 x 10-6K-1
Specific Heat capacity = 2.74 KJ/kg k
Assuming
Pump Efficiency = 75 %
equations used for pump :
Ws(isentropic)=V (P2-P1)=Hs ----------- (i)Hs=Ws ------------ (ii)
Hs = CpdT+ V(1-T)P[1] ----------- (ii)
Using equation (i) (ii) and (iii)
we get Ws= 5.24kJ/kg Hs = 6.98 kJ/kg,
and temperature rise to be 2.5 0 c , So final temperature is 57.540 c and pressure is 42 atm out of adiabatic
pump of 9.67 hp
Pressure inlet 1 atm
Temperature 55 c
Mass flow rate 1.034kg/sec
Pressure Inlet 42 atm
Temprature 57.54 c
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Centrifugal Pump
Density of
methanol
791.8 kg/m3
Flow rate 30 gpm , 1.8
kg/ sec
Presuure 1 atm
Temperature 55 0C
RPM 1900
Suction head
loss
0.469 m of
methanol
Total
dynamic
head
13.62 m =
44.7 feet of
methanol
WHP 0.6 hp
BHP(with eff.
0.75)
0.8 hp
Length of
pipe
50 m
Friction factor 0.0193
Total
frictional
head loss
0.78 m of
methanol
Diameter of
pipe(standar
d stainlesssteel)
1.0 in
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Reactor Design
FAo (molar flow rate of
methanol)
132948 mol/hr
X (conversion of methanol) 0.98
(-rmethanol)exit 30.3 mol/ gcat-hr
W (weight of catalyst inreactor)
1.225 kg
Bulk density of catalyst 12410 kg /m3
Volume of catalyst in reactor 9.87 x 10-5m3
Volume of slurry in thereactor with s=0.3
3.29 x 10-4m3
Diameter of tank with
(L/D=5)
2.57 m
Height of the reactor 13 m
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Bubble specifications
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Gas Absorber
Gases Volume (gmol) % volume
CO 3545 23.66
CO2 360 2.40
CH4 75 0.50
HI 60 0.40
CH3I 10940 73.03
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Assumptions
gas and liquid streams flow through the
absorber not change appreciably
90% reduction of CH3I from Inlet
concentration
75% Flooding Velocity
Stream Flow rate = 1.77m3/min
Temp = 328K and pressure = 1atm
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Calculation for Tower Diameter
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Calculation for Tower height
Z = Height
HTU = height of transfer
unit
NTU no of transer unit
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Final Data for absorber
Diameter 1.6m
Height 5.1m
Area 2.24m2
Number of Transfer units 2.43
Gas flow rate 68.35 g-mol /min
Liquid Flow rate 2187.5 gmol/min
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Packing Data
Packing used here is Intalox saddles (plastic)
Size - 2in
Weight - 38(lb/ft2)
Surface area/packing volume - 36 ft2/ft3
VOid Fraction - 79%
Packing factor - 40ft2
/ft3
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Crude Fractionating Column
Extractive Distillation:No azeotropic
High Boiling
Low relative volatility
Fig#1 C 301 Crude Fractionating Column
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Designing:
Column Diar
References: Coulson and Richardson: Volume 6, Tamkang Journal of Science and Engineering, Vol. 4, No. 2, pp. 105-110 (2001)
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HydraulicsColumn Diameter
Fair Correlation
Total Column Area: Ac= An+ Ad
Liquid Flow
Arrangement
Cross Flow
Active area Aa=Ac-2Ad
Weir length Ad / Ac
Plate DesigningMinimum Vapor
Velocity
Crest Depth how=750[(Lm/lw*)2/3]
Check Weeping
References: Coulson and Richardson: Volume 6, Tamkang Journal of Science and Engineering, Vol. 4, No. 2, pp. 105-110 (2001)
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Dry Plate Drop
Total Pressure Drop
DowncomerBack-up
hb= (hw+ how) + ht+ hdc
Head Loss
Residence Time: tr=AdhbcL/L(max)
Entrainment: Fractional entrainment ()
Number of Holes: Area of 1 Hole = (/4)
Dhole2
Pressure Drop
Downcomer
Liquid Backup
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Design Data
No. of trays 68
Pressure 101.325 kpa
Height of column 35m
Diameter of column 1.45m
Hole size 5mm
Pressure drop per
tray
1.2kpa
Tray thickness 5mm
Vapour Flow Ratelbmol/hr
331 lb mol/hr
Downcomer liquid backup 0.20mm
Actual minimum Vapor
Velocity
12.81 m/sec
Active holes 5900
Weir Height 50mm
Weir Length 1m
Reflux Ratio 6.23
Tray Spacing 0.5m
Active Area 1.16 m2
Percentage
Flooding
85%
Entrainment 0.075
Liquid Flow rate 880 lbmol/hr
Residence time 10 sec
MIn. Designing
Vapor Velocity
9m/sec
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Refining Column
Refining column mass balanceTotal Distillate Rate =2Kg/sec
Compound Mass Flow Rate
(Kg/sec)
Mole Flow Rate
(KMol/sec)
Mole Fraction
(Percentage)
Acetic acid 1.97 3.28 x 10-2 98.73
Propionic Acid 0.03 4.21 x 10-4 1.27
Feed Flow Rate =2.29 Kg/sec
Acetic Acid 2.22 3.28 x 10-2 97.75
Propionic Acid 0.07 9.49 x 10-4 2.25
Bottom Flow Rate =0.29 Kg/sec
Acetic Acid 0.25 3.28 x 10-2 86.45
Propionic Acid 0.04 4.42 x 10-4 13.54
Design and optimization of a dividing wall column for debottlenecking of the acetic acid purification process
By:-Nguyen Van Duc Long, Seunghyun Lee, Moonyong Lee Chemical Engineering and Processing 49 (2010)
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Temperature inside
the column=400 K
Pressure=100 Kpa
Column Height
Ideal No. of tray 4
Actual no. of tray 6
Tray spacing 0.5 m
Column height 3 m
Mass transfer operation By:-Robert E. Treybal Third Edition
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Column Diameter
Gas density G1.81 Kg/m3
Vapor rate Q 1.01 m3/sec
Liquid density L725.175 Kg/m3
Liquid flow rate 4.21 10-4m3/sec
Hole diameter 3 mm
plate thickness(0.65 *Hole
area)
1.95 mm
Pitch ( P'=hole diameter/0.33) 9.09 mm
Downspout area
Hole area/Activearea=0.907x(d0/l)2
98.79 10-3
Mass transfer operation By:-Robert E. Treybal Third Edition
http://profmaster.blogspot.in/2007/06/surface-tension.html(surface tension)
Fluid Phase Equilibria 54 (1990) Masahiro kato, Hiroshi yoshikawa and Yamaguchi Dustrial chemistry
department of faculty of engineering Nihon University Koriyama Fukushima Japan
http://profmaster.blogspot.in/2007/06/surface-tension.htmlhttp://profmaster.blogspot.in/2007/06/surface-tension.htmlhttp://profmaster.blogspot.in/2007/06/surface-tension.htmlhttp://profmaster.blogspot.in/2007/06/surface-tension.html7/27/2019 Sub group 43
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Weir Crest h1and weir height hw
q/Weff=1.8939 h13/2
When taking W= Weff h1=5.78 10-3m
Weff = 0.9656 W
again
=5.89 10-3m
Repeat with new value of h1 Weff= 0.9649 W so h1=58.94 10-4m Set weir height hw= 0.012 m
Net tower cross section area of gas
flow Anf=Q/V
0.68 m2
Tower cross-sectional area At=An/(1-
downspout)
0.711 m2
Tower Diameter T=[(4At)/]0.5 95.15 x 10-2 m
Weir length W =0.55T 52.33 10-2m
Liquid rate /weir length (q/W) 8.04 10-4 m2/m-s
Active area 53.59 10-2 m2
for perforated sheet
Mass transfer operation By:-Robert E. Treybal Third Edition
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Because h1+ hw+ h3< t/2 so my assuming tray spacing (0.50) its perfectly satisfied
Weeping will not occur till velocity through orifice reduce to weeping velocity
Dry Pressure Drop 4.62 10-2m
Hydraulic Head HL 8.25 10-3m
Residual Pressure Drop 8.85 10-4m
Total gas pressure drop 5.938 10-2m
Tray pressure drop 0.00256 psi or 17.650547 Pa
Pressure loss at liquid
entrance
0.56 10-2m
Ada 0.31 10-2m
Backup in downspout 6.4 10-2m
Checking on flooding =81.89 10-2m
Weeping Velocity 0.068 m/sec
Weir set = 0.418 T 0.3978
Z=2 Times weir set 79.56 10-2m
Entrainment 0.0035
Mass transfer operation By:-Robert E. Treybal Third Edition
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Tray Performance Constraints
1.Foaming:-It's depend on material property.
2. Entrainment:-The entrainment is too small to influencethe tray hydraulics appreciably.
3.Flooding:-flooding will not occur until velocity V isincrease above flooding velocity.
4.Weeping:-The tray will not weeping excessively until thegas velocity through the hole Vois reduced to close thisvalue.
5. Downcomer flooding:it's happened when liquid rate ishigh and vapor flow rate is less.
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End Stripping Column
Plate or Packed Column:
Packed column was selected for the reasons given below: Good liquid distribution can be maintained throughout
Economic to replace packings than trays in case of fouling
Since the liquid is corrosive hence packed column is relatively cheaper
Liquid holdup is comparatively lower in packed columns. Important in caseof flammable inventory
More suitable for handling foaming systems
Relatively lower pressure drop
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Choice of Packing:
Random packing of 0.038m
ceramic intalox saddle has
been chosen for the followingreasons:
One of the most efficient
packings
Little tendency to nest and
block areas of bed
Gives a fairly uniform bed
Higher flooding point
Lower pressure drop
Packing Details
Packing Factor 52
Dry Bed Packing
Factor
50
Mass 624 kg/m3
Surface Area 195 m2/m3
Voidage 76%
Min. Wetting Rate 3.4x10-6m2/s
Material Balance:
D i C l l ti
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Design Calculations:
Harriott, P. Chemical Reactor Design. New York: Marcel Dekker, 2003; Chapter 8
Carl R. Branan. Rule of Thumbs for Chemical Engineers, 4th ed. Butterworth-Heinemann, 2005; p. 109-113; p.143-
152Perry, R.H., and D.W. Green. Perrys Chemical Engineers Handbook, 7th ed. New York: McGraw-Hill, 1997; p. 15-86
Parameter and Equations Calculated Value
1 Height Equivalent of Theroretical Plate
(HETP)
0.035 m
2 Number of Transfer Units 5
3 Height of overall Gas Transfer Units 1.45
4 Column Height:
HTotal= HOGx NTotal
7.78 m
5 Diameter of Column: 0.83 m
M h i l D i
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Mechanical Design:
Parameter and Equations Calculated Value
1 Thickness of Shell (ts): 30.8 mm
2 Shell Weight (W):
W= Vol. of Shell x Density of Material
9670 kg
3 Head Selection and Thickness (th): 32 mm
4 Head Weight (Wh): 58 kg
Gavin Towler, R.K. Sinnott. Chemical Engineering Design: Principles, Practice and Economics of Plant and Process
Design, 2nd ed. Butterworth-Heinemann, 2013; p. 279-302; p. 807-923
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Heat ExchangerPreliminary calculations
Procedure for estimating area
Shell side Q= W*C*dT
Q=4254.34*0.64*(180-57)
Q=334901644.8 cal = 1402166.206449 KJ = 1.402 * 106 KJ
LMTD = (T1-t2)-(T2-t1)/(ln(T1-t2)/(T2-t1))
=((198-180)(108-57.546))/ln((198-108)/(108-57.546))
=48.88 deg C
Assumed data: Di = 1.049 inches = 0.0874 ftDO = 1.315 inches = 0.1096 ft
XW = 0.133 inches = 0.0111 ft
Methanol coefficient = 1020
Water = 1700
Inside Fouling Factor = 5680
Outside Fouling Factor = 2840
DL = (DODI)/(ln(Do/DI)) = (0.10960.0874) / (ln(0.1096/0.0874)) = 0.0983 ft
Overall coefficient, UO = 459 W/m2 deg C
Total outside heat transfer area, Ao = Q/Uo*LMTD
= 1402166.20/(459 * 48.88)
=62.49 sq m
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Pinch Design Method
Stream no Stream type Het capacityFlow rate
Source
temperature
Target
temperature
1Hot 6 200 65
2 Hot 3 90 30
3 Cold 3.5 57.5(temp from
the absorber)
180(final temp as
reqd in the
reactor)
4 Cold 4 25 130
Reference :
B. LINNHOFF and E. HINDMARSH
THE PINCH DESIGN METHOD FOR HEAT EXCHANGER NETWORKS
Department of Chemical Engineering, University of Manchester Institute of Science and TechnologyChemical Engineering Science Vol. 38, No 5 pp 745-763, 1983
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Hot End Design
Design 1 Design 2
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Cold End Design
Design 1 Design 2
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Liquid effluent column
absorbent - CaO 75%-MgO 25%
Mass of absorbent 1.31 kg
L/D 1.75
porosity 0.4
Diameter of spehrical particle 1um
Diameter 5.5
Height of tower 9.625
total No. of particle 771*10 18
total no. of particle in 1 layer 96.35 *10 12
height of absorbent bed 8m
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Storage of acetic acidL/D ratio ?
Design and construction of tank
Stainless steel grade 304 ,316,314
High density polyethene
.propylene and rubber lined carbon steel
hydrostatic gauge fabricated with stainless steel of suitable grade
gauge glass covered from all sides (especially for 80% acetic acid).self- priming centrifugal pumps mechanically sealed with PTFE wedges
pvc or polypropylene ball valves
earthing should be provided
The fitting of low and high temperature alarms
ACETIC ACIDCORROSIVE TO SKIN
Emergency instructions, in case of splashing
eye baths or wash bottles containing water
Buckets of sodium bicarbonate
i
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Storage of raw material (methanol)
Design and construction of tankcarbon steel with interior surface coated with epoxy resin.
side ways agitator according to API-650
volume of raw material 113597m3
L/D 0.5
diameter 13.65m
height 6.825m
no. of tanks 14