Distillation - Basics

5/24/2018 Distillation - Basics

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LABORATORY DISTILALTIONS AND

INTERCONVERSIONS OF DATA

Dr Y.K.SHARMA

INDIAN INSTITUTE OF PETROLEUM

DEHRADUN-248005, INDIA

(AN ISO-9001 R & D INSTITUTE)


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PRINCIPLE OF DISTILLATION


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Distillation

Separation of components from a mixture

due to difference on their volatility.

To concentrate the more volatile component

(mvc) in the vapor phase than in liquid phase

on contact of two phases.

For higher degree of separation columnconsist vertically arranged separation stages.


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Equilibrium Ratio

Distribution of any component of the

mixture of solution between liquid andvapour phase.

Roults law: Relates partial pressure of a

component to its concentration in liquid at

equilibrium

pi

= xi

Pi

(pi

partial pressure of componenti

)

(xi Mole fraction of i in solution)

(Pi VP of i at same temp.)


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Daltons law

pi= yiP(yi mole fraction of component in vapor)

(P total pressure of the system)

Combining these Laws: Mole fraction of

component in vapor/mole fraction of

component in liquid = Ki

Ki= yi/xi= Pi/P

(Phase equilibrium constant at specified

temperature and pressure)


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Economic Significance

DistillationDetermines the capacity of the installations

that provide steam, fuel and cooling water

for the refinery.

Cost of distillation columns accounts 10-12%

of the total investment in process equipment

Total cost of equipment 3 times that of

column alone.


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LAB DISTILLATIONSNon Fractionating

ASTM D-86 Distillation/ASTM D-1160

Raylelgh Vaporisation

Equilibrium Flash Vaporisation (EFV)

Semi Fractionating

Hemple Distillation

VAC Still, Sarnia High / POT Still

Molecular Still / Short Path Distillation

Fractionating Distillation TBP Distillation

Packed Column

Sieve Plate Column (Oldershaw)

Simulated Distillation


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Non fractionating distillations

Liquid mixture is partially vaporized and the

vapor and liquid are allowed to separate

there is an increase of concentration of the

more volatile components in the vapor phase

and the less volatile components in theliquid phase.

Vaporization effected by heating the liquid

or reducing the pressure.

(Degree of separation is not high (ASTM D-86) but may be increased by carrying out theflash (EFV) in number of stages. (e,g Wellhead

separation of gases from crude oil.)


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Distillation cuts in the MM-AEBP plot

Atmospheric Equivalent Boiling Point

MolarMass

ParaffinsC

nH2n-2


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Atmospheric Distillation

ASTM D86/IP123/P18

Apparatus and Operating Conditions

Flask Capacity : 125 ml

Sample Quantity : 100 ml

Condenser Temp. : Depends on fuel

Time for Application of Head IBP: 5-15 min

Av. Rate of Recovery : 4-5ml/min

Time for 95% Rec. to FBP : 3-5 min

No reflux

For gasoline, kerosene and diesel)


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Distillation Characteristics of Petroleum

Products (IP123) (ASTM D86)

Apparatus Assembly using a Gas Burber


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Volatility Characteristics

Typical Distillation Curve for Gasoline

A. Distillation ASTM D86


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ASTM D1160

Completely vaporize under reduced pressure

and gives an idea about the range of higher

fraction

In manual distillation a chain is attached to

the tip of receiver known as anti tip chain.

All these distillations are standardize to TBPdistillation.


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Vacuum Distillation ASTM D1160

Apparatus and Operating Conditions

Flask Capacity : 500 ml

Sample : 200 ml

Distillation Rate : 4-8 ml/min

Coolant Temperature : Depends on sample

Pressure : 4mm/10mm


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DISTILLATION

NON FRACTIONATING SEMI FRACTIONAING FRACTIONATING DISTN

TBP DISTN

BATCH DISTILLAION


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OBJECTIVE

PREPARATION OF FEED STOCK

TO MONITOR & CONTROL QUALITY OFPRODUCT

TO GENERATE YIELD DATA ON %WT/VOL

TO STUDY THE VARIATION OF SOME KEYPROPERTIES THROUGHT OUT DISTN RANGE

DATA IS THE BASIS OF PROPERTY CURVEWHICH CAN BE USED FOR PRODUCTOPTIMIZATION

TO INDICATE WHAT FURTHER PROCESSINGOF TREATING IS REQ TO MEET THEREQUIREMEN OF SPECIFICATION

ASSESSING THE COST OF CRUDE OIL


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TYPES OF COLUMNS

OPEN COLUMNS

BUBBLE TRAY

PERFORATED SEIVE TYPE

PACKED COLUMNS


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PACKING MATERIAL

PRO PACK

HELIX PACK

STEADMAN

CANON PACKING

KNIT WIRE


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Typical TBP Distillation Arrangement


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Average TBP Distillation of Crudes


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Equilibrium Flash Vaporisation

Distillation Curve

A curve of equilibrated vaporized percentage

at different temperatures

Generally determined by correlation methods

Very useful design data for distillation units


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IBP (Initial boiling point) It is comparatively

lower for TBP than ASTM distillation.

IBP of ASTM is lower than Releigh,svaporization. IBP of EFV is highest among

all.

FBP (Final boiling point) Highest for TBPthan ASTM but Releigh,s FBP is higher than

ASTM. FBP is lowest for EFV.


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Typical TBP, ASTM, EFV Curves


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Average Boiling Points

Data Book on HydrocarbonsJ B Maxwell


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Average Boiling Points

Data Book on HydrocarbonsJ B Maxwell

INTERCOVERSIONS OF DISTILLATION DATA


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INTERCOVERSIONS OF DISTILLATION DATA

Reliability of Results

Maxwell Method (Data book on hydrocarbons)

Av. Deviation of converted to experimental 10 to 15F

Admister Method (Applied hydrocarbons thermodynamics)

At atmospheric and higher pressure

ASTM to TBP, Av. Deviation : 7F

TBP to EFV, Av. Deviation : 6F

ASTM to EFV, Av. Deviation : 9F

Under Sub-Atmospheric Pressure


TBP to EFV, Av. Deviation : 6F


E ilib i Fl h V i ti


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Equilibrium Flash Vaporization


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Maxwell Method


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Maxell Method

Interrelationships between empirical cor


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Interrelationships between empirical cor-

relations relating ASTM-TBP-EFV at 760

and 100 m Hg Pressure

Date Book on HydrocarbonsJ B Maxwell (Piromov & Beiswanger)

(i) ASTM D 86 ---- EFV

(ii) TBP ---- EFV

Applied Hydrocarbon TehermodynamicsW C Admister

(Edmister & Pollock)


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TBP Temp. Difference Vs EFV Temp.

Difference

TBP EFV

TBP 50 P t T t V EFV


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TBP 50 Percent Temperature Vs EFV

Percent Temperature

TBP EFV

ASTM 50 P t T t V


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ASTM 50 Percent Temperature Vs

LFV 50 Percent Temperature

ASTM EFV

ASTM T t Diff V EFV


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ASTM Temperature Difference Vs EFV

Temperature Difference

ASTM EFV


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Short Path Distillation

Falling Film Units

Formation of hot spots with overheating and product cracking

Non optimal distillation rates as a

result of formation of laminar films

A high temperature difference in

the product film Vacuum limited to 20 mbars due to

restrictions in vapor flow

Wiped Film, Short Path Evaporator Large free flowing area for vapors

Optimum vipers desing

Optmization of heat transfer and

condction in product films

Smallest hold up


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SPD EVAPORATOR


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SHORT PATH DISTILALTION UNIT

UIC-KDL5 CADI

Technical Data

Throughput : max. 1kg/h

(depending on product)

Evaporator Surface : 4.8 dm2

Condenser Surface : 5.6 dm2

Evaporator Temp. : max. 350C

Working Pressure : down to 0.001 mbar


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Short Path Distillation


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Short Path and Conventional Distillation

Short Path

Distillation

Packed

Column Vac.

Distillation

Operational Mode Continuous Batch

Pressure 10-3mbar 0.05-0.1 bar

Feed Heating Thin Film Reboiler

Heating Duration 10-60 sec. 1-10 hrs

Heated Condensing

Surfaces

1.5-3 cm 50-150 cm

Column packing None Packing

Maximum Cut Point, AET 700C

(1300F)

560C

(1040F)

Separation Principal Kinetic Phase

Equilibrium

SPD RUNS


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SPD RUNS

Digboi Short Reside

Run No. 4 3 11Cut No D 1 2 1 1

Evaporator Temp.C 300 325 300 340

Vacuum mbar 4.16E-2 1.9E-2 4E-2 4.1E-2

Feed Rate g/h 856.8 957.0 924 945.6% Distillate 29.4 44.8 28 44.75

% Residue 70.6 55.2 72 55.25

Sim Dist. Of Distillate C

5% off 486 422 422 -

50% off 566 560 559

95% off 617 624 623

FBP C 633 639 633

SPD RUNS


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SPD RUNS

Kuwait 550C

Run No. 5Cut No. 1 2

Evaporator Temp. C 300 320

Vacuum mbar 1.47E-2 1.45E-2

Feed Rate g/h 564 585

% Distillate 34.0 40.5

% Residue 66.0 59.5

Distillate Sim Dist

5% off - 427

50 % off - 562

95% off - 619

FBP - 629

Boiling Range Distribution by Gas


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Boiling Range Distribution by Gas

Chromatography


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SIMULATED DISTILLATIOND2887

Typical Conditions

Column length 1.2 mLiquid phase OV-1 SE 30, UC-W98

Def. Temp. 350C

Inf. (FID) Temp. 350C

Oven Temp. Ini -30

Final 350C

Oven Temp. Prgo. Rate 10


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THANK YOU

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Distillation - Basics