liquid liquid extraction unit

8/15/2019 Liquid Liquid Extraction Unit

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EXPERIMENTAL MANUAL

SOLTEQ® EQUIPMENT FOR ENGINEERING EDUCATION & RESEARCH

EXCESS FEED

MATERIAL

RECOVERY

EXCESS FEED

MATERIAL

RECOVERY


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TABLE OF CONTENTS

LIST OF FIGURES…………………………………………………………………………………………...i

1.0 INTRODUCTION.................................................................................................................. 1

2.0 GENERAL DESCRIPTION .................................................................................................. 3

2.1 Description and Assembly ....................................................................................... 32.2 Valves and Instruments List .................................................................................... 52.3 Experiment Capabilities .......................................................................................... 62.4 General Requirements……………………………………………………………………6

3.0 SUMMARY OF THEORY ..................................................................................................... 7

4.0 OPERATING PROCEDURES ............................................................................................ 10

4.1 General Start-Up Procedure ................................................................................. 104.2 General Shut-Down Procedure..............................................................................11

4.3 Cleaning Procedure …………………………………………………………………….11

5.0 OPERATING PROCEDURES

5 1 Experiment 1: Extraction of Acetone From Water Using Toluene 12


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SOLTEQ® CHEMICAL PROCESS PILOT PLANT (EXCESS FEED MATERIAL RECOVERY SYSTEM) (Model: BP533-CPP)

List of FiguresPage

Figure 1 Process Flow Diagram for the Liquid-Liquid Extraction Unit 2

Figure 2 Flow of Streams and Components in a Liquid-Liquid Extraction System 7

Figure 3 A Typical 3-Component System Representation on an EquilateralTriangular Diagram

8

Figure 4 Operating Lines and Tie Lines Constructions for Determination ofExtraction Efficiency

9


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1.0 INTRODUCTION

The Excess Feed Material Recovery System of the SOLTEQ® Chemical Process PilotPlant (Model: BP533-CPP) can be used to demonstrate the efficiency of separation andrecovery of recyclable materials. The apparatus requires a cold water, hot liquid from heatexchanger system, and a triple phase electrical outlet to enable a series of simplemeasurements to be made by students needing an introduction to excess feed materialrecovery design and operation. This experiment allows the student to understand someimportant things in this system which are:

Mass and energy balances Concept in separation process mainly in liquid-liquid extraction Liquid sampling on the bottom of extraction column to determine the practicalseparation behavior of the particular mixture.

This experiment consists of two important equipments which are extraction column andsolvent recovery column. Two flowrate transmitter are installed in both inlet of extractioncolumn (top and bottom column) and valves are incorporated in both inlet to regulate theflow. On the other hand, one temperature measuring device are installed in the outlet ofsolvent recovery column.

The process flow diagram for the excess feed material recovery system is given in Figure1


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2.0 GENERAL DESCRIPTION

2.1 Description and Assembly

Before operating the excess feed material recovery system, users must familiarizethemselves with all the components of the unit. Please refer to Figure 1 to understand theprocess.

Solvent Tank (V-113)

Material : SS 304Capacity: approx. 25-LDimensions: 0.290m (D) x 0.400m (H)

Feed Tank (V-114)

Material: SS 304Capacity: approx. 25-LDimensions: 0.290m (D) x 0.400m (H)

Settling Tank (V-115)

Material: SS 304Capacity: approx. 70-LDimensions: 0.400m (D) x 0.560m (H)

R ffi t T k (V 116)


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Product Pump (P-115)

Material: SS 304Type: Vertical Centrifugal pumpCapacity: 10 LPH @ 35m headRating: 0.37 kW

Transfer Pump (P-117)

Material: SS 304Type: Vertical Centrifugal pumpCapacity: 10 LPM @ 35m headRating: 0.37 kW

Reboiler 2 (E-407)

Material: SS 304Capacity: 20 LElectrical Heater: 2 x 2 kW

Condenser 3 (E-408)

Type: Coil Heat ExchangerMaterial: SS 304

A 0 52


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2.2 Valves and Instruments List

Valves list:

Tag Location

HV 601 V-113 drain valve

HV 602 V-113 outlet valve to pump, P-113

HV 603 T-501 (bottom) inlet valve


HV 605 V-114 outlet valve to pump, P-114HV 606 T-501 (top) inlet valve

HV 607 T-501 (bottom) drain valve

HV 608 T-501 (top) drain valve


HV 610 E-407 inlet valve

HV 611 V-115 inlet valve from HEXHV 612 V-115 cooling water drain valve

HV 613 E-407 drain valve

HV 614 E-408 sampling/drain valve


HV 616 E-408 cooling water outlet valve

HV 617 V 117 tl t l


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Additional Note:

All piping are 3/4" stainless steel 304 tubing unless stated otherwise.

2.3 Experimental Capabilities

a)

Determination of the mass and energy balance of excess feed material recoverysystem.

b) Demonstration of the effect of feed flow rates on the flowrate efficiency.c) Study concept of thermodynamics of liquid-liquid system.d) Study the operation of liquid-liquid extraction and solvent recovery system.e) Demonstration of the effect of solvent to feed ratio on the extraction efficiency.f) Demonstration of the effect on of organic and aqueous phase as continuous phase.g) Determination the number of theoretical plates for the extraction column.

2.4 General Requirements

Electrical : 415 VAC/ 50Hz (3-phase)Cooling water : Laboratory tap water


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3.0 SUMMARY OF THEORY

When separation by distillation is ineffective or very difficult, liquid-liquid extraction is one ofthe main alternatives to consider. Close boiling mixtures or substances that cannotwithstand the temperature of distillation, even under a vacuum, may often be separatedfrom impurities by extraction, which utilizes chemical differences instead of vapor pressuredifferences.

Separation by liquid-liquid extraction can be defined as the selective removal of one ormore components either from a homogeneous liquid mixture or from a solution, using asecond liquid or solvent, which is partially or wholly immiscible with the first.

The following terms are widely used to describe the different streams in a liquid-liquidextraction system:

F : FeedS : Solvent

R : RaffinateE : Extract

solvent,S

extract, E

l t

EXTRACTION PROCESS


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The liquid used to strip the solute from the feed is referred to as the solvent. However,solvent is a general term and should not be confused with the feed solvent or diluent. The

solvent after becoming enriched in solute leaves the system as the extract.It is also important to define the composition of the four streams and this may be done inseveral ways:

a) Molar concentration = mol/dm3 (note numerically this is the same as kmol/m3)b) Molal concentration = mol/kg

c) Mole fraction, x A =

molesof no.Total

Amolesof No.

d) Mole ratio, x A/B =Bmolesof No.

Amolesof No.

e) Mass fraction, x A =massTotal

Aof Mass

f) Mass ratio, x A/B =Bof Mass

Aof Mass

Note: Fractions and ratios are dimensionless and may also be expressed in percent (%).The common basis used in most literatures are either mole or mass fraction.

Since liquid-liquid extraction involves a 3-component system, a graphical representation ofthe liquid mixtures is usually employed. There are two graphical systems, namely:

) R t l di t


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Figure 3: A Typical 3-Component System Representation on an Equilateral Triangular Diagram The individual components of the chosen ternary system are usually represented bysymbols as follows:

A = SoluteB = DiluentC = Solvent

The assignment of symbols are arbitrary. Confusion shall not arise as long as the apex forthe solute is at the top while the bottom apexes are for the solvent and diluent.

Referring to Figure 3, the curve on the triangular diagram is called the binodal or solubilitycurve of the ternary system. The curve, which is essentially a combination of diluent-richand solvent-rich curves, separates the upper region of stable single phase mixture from thelower region of unstable mixture, which tends to separate into two phases.

The compositions of extract, E and raffinate, R are connected by tie-lines having differentslopes (i.e. not parallel). The tie lines get shorter as they get away from the x-axis, andeventually they converge at a point P (plait point). The point P is not normally the highestpart of the curve.

The number of theoretical stages can be determined graphically by constructing operatinglines and tie-lines on the binodal/solubility curves, as outlined in Figure 4. Consequently,

h ff f diff i d d f d fl h i ffi i


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The following chemicals will be used in the experiment:

a) Acetone (solute)b) Water (diluent)c) Toluene (solvent)

4.1 General Start-Up Procedure

1. Prepare the following chemicals:

a) Feed (heavy phase): mixture of acetone-water solution at the desiredcomposition

b) Solvent (light phase): pure toluene

2. Ensure that all valves are closed.

3.

Turn on the power of the control panel and SOLDAS® Software.

4. Open valves HV620 and HV621.

5. Fill solvent V-113 with pure toluene solvent and feed tank V-114 with acetone-water solution.

6. Close all valves except outlet vessel valves (HV 602 and HV 605).

7. Open valve HV606. Switch on pump P-114. Allow the acetone-water solution


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4.2 General Shut-Down Procedure

1.

Make sure turn off all pumps (P-113, P-114, P-115 and P-117) and the heaterof reboiler 2 E-407.

2. Open valves HV 615, HV 617, HV 613 and HV 609 to drain all chemicals fromthe tanks.

Note: Make sure temperature TIC-113 in the reboiler, E-407 is drop to roomtemperature before drain the chemicals.

3.

If the equipment will not use for a long period, follow procedure 4.3 to cleanthe equipment.

4. Turn off the power for the control panel.

4.3 Cleaning Procedure

1. Drain all chemicals in tanks, columns and reboiler 2.

2.

Fill feed tanks (V-113 and V-114) with filtered water.

3. Open HV 602, HV 603, HV605 and HV 606.

4. Switch on pump P-113 and P114 to pump all water to the extraction column,T-501.

5. Switch off P-113 and P-114.

6. Repeat steps 1 to 5 using alcohol (methanol) if necessary.


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5.1 EXPERIMENT 1: Extraction of Acetone from Water Using Toluene

In this experiment, there are two feeds and two outlet flows from the column.Feed flows:Solvent: Toluene (light phase)Feed: Acetone-water mixture (heavy phase)

Outlet flows:Extract : Toluene rich phaseRaffinate: Water rich phase

OBJECTIVE:

1. To study mass balance of the system2. To study the effect of feed flow rates on the extraction efficiency

PROCEDURES:

1.

Ensure that all equilibrium and calibration data are obtained (Appendix H).

2. Perform the general start-up procedures (Section 4.1).

3. Start both pumps P-113 and P-114 and set the desired feed and solvent flowrates by adjusting the pump speed controller or/and HV 603 and HV 606respectively.

4. Allow both liquids to flow into the collection tanks V-115 and V-116


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ANALYSIS AND DISCUSSION:

1. Determine the required theoretical extraction stage from the liquid-liquidextraction experiment results. Refer to Appendix B for a step-by-stepcalculation guide.

2. Calculate the height equivalent theoretical plates (HETP) of the extractioncolumn for different rotating disc speed.

HETP = platesltheoreticaof No.

heightcolumnEffective

3. Calculate the separation efficiency for different solvent to feed ratios androtating speed.

Efficiency =feedinsoluteof Amount

soluteextractedof Amount

=ncompositioFeedflowrateFeedncompositioExtractflowrateExtract

4. Compare the HETP values or separation efficiency for different solvent to feedratio.


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5.2 EXPERIMENT 2: RECOVERY OF SOLVENT

Objective:

1. To study the thermodynamics of liquid-liquid systems

2. To study the operation of liquid-liquid extraction and solvent recoverysystem

Procedure

1. Open HV 610 and HV 622.

2. Switch on pump, P-115 to transfer extracted solution to reboiler 2 E-407.

3. Observe the level of extracted solution. Turn off pump, P-115 immediatelywhen the level of extracted solution is ¾ volume of total volume of thereboiler, E-407.

4. Close HV 610 after transfer extracted solution to the reboiler 2 E-407.

5. Open HV 623 and HV 624 to supply cooling water to condenser, E-408 bycontrolling the flowrate of water using HV 616 to 15 L/min.

6. Switch on the heater in the reboiler, E-407 and adjust the power of heater


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6.0 REFERENCES

1.

McCabe, Smith & Harriott, “Unit Operations of Chemical Engineering”, McGraw Hill,(Singapore), 2001.

2. Robert E. Treybal, “Mass Transfer Operations”, Third Edition, McGraw Hill Book Co.(Singapore), 1980.

3. Robert E. Treybal, “Liquid Extraction”, Second Edition, McGraw Hill Series, 1963.

4.

Institution of Chemical Engineers, “Standard Test Systems for Liquid Extraction”,Second Edition, 1985.


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7.0 MAINTENANCE AND SAFETY PRECAUTIONS

1.

The unit must be operated under the supervision of trained personnel.2. All operating instructions supplied with the unit must be carefully read and understood

before attempting to operate the unit.

3. Always check and rectify any leak.

4. Always make sure that the heater is fully submerged in the water.

5. Do not touch the hot components of the unit.

6.

Be extremely careful when handling liquid at high temperature.

7. Always switch off the heater and allow the liquid to cool down before draining.

8. Restore the system to operating conditions after any repair job.

9. Only properly trained personnel shall be allowed to carry out any servicing.Manufacturer's manual must always be observed.

10.

Before servicing, shut down the whole operation and let the system to cool down.


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APPENDICES


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APPENDIX A

SAMPLE TABLE FOR EXPERIMENT EXPERIMENT 1

Run No.Feed

flow rate(L/min)

Solventflow rate(L/min)

Solventto feedratio

RotatingDisc

Speed(RPM)

Time(min)

Raffinate Extract

HETP(mm)

SeparationefficiencyRefractive

index

Solutecomposition

(wt%)

Refractiveindex

Solutecomposition

(wt%)


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EXPERIMENT 2: RECOVERY OF SOLVENT

Time (min) Refractive Index (RI) Purity of Solvent (%)


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APPENDIX B

STEP BY STEP CALCULATION GUIDE

1. Obtain the equilibrium data from Appendix D or from literature. Plot the binodal/solubility curveand the corresponding tie lines on a triangular plot (Appendix G).

2. Locate the points for:Feed, FSolvent, SRaffinate, RExtract, EFeed and solvent mixture, M

acetone

watertoluene

F

S

R

E

M


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4. Draw a tie line from point E to its equilibrium point on the binodal plot. Connect an operatingline from that equilibrium end of the tie line to point ΔR. Extend that operating line so that it

intersects with the binodal plot at the other end. Draw another tie line from that new intersectionand continue until a tie line has passed the operating line connecting R and S.

acetone

watertoluene

F

S

R

E

ΔR


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APPENDIX C

CALIBRATION PROCEDURES FOR LIQUID-LIQUID EXTRACTION EXPERIMENT

C.1 Determination Of The Binodal/Solubility Curve

OBJECTIVE:

To obtain the binodal/solubility curve for both toluene and water rich phases.

APPARATUS:

1. Conical flasks, measuring cylinders, titration apparatus.2. Refractometer for calibration.

PROCEDURES:

1. Record the average ambient temperature throughout the experiment and obtain the

pure component densities for acetone, water and toluene at the experimenttemperature.

Toluene rich phase

2. Prepare 6 homogenous mixtures of acetone and toluene in 6 different conical flasksaccording to the recommended composition listed in the first table in Appendix D.

3. Prepare the apparatus for titration and fill the burette with water.


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amount of toluene that has been added. This is known as the cloud point where allthree components are in equilibrium and this represents a point on the ternary

binodal/solubility curve.5. Take about 10 mL sample of the ternary mixture and measure the refractive index

using a refractometer. Take 3 series of readings for the same sample and record theaverage.

6. Repeat the experiment (steps 9 to 12) for all 6 mixtures. Calculate the mass fraction ofeach component during equilibrium and record the results in the second table in

Appendix D.

ANALYSIS AND DISCUSSION:

1. Use the sample tables in Appendix D for data collection.

a) For the toluene rich phase, after titration with water, enter the volume of waterrequired for ternary equilibrium. From the knowledge of pure densities for eachcomponent, calculate their mass fraction in the mixture. Enter the refractive index

for each mixture in the appropriate column.b) For the water rich phase, after titration with toluene, enter the volume of toluene

required for ternary equilibrium. Again, from the knowledge of pure densities foreach component, calculate their mass fraction in the mixture. Enter the refractiveindex for each mixture in the appropriate column.

2. Plot the refractive index of each mixture as a function of acetone (solute) composition.Do a separate plot for the toluene rich phase and water rich phase. This will serve as


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C.2 Determination of Equilibrium Solute Distribution (Tie Lines)

OBJECTIVE:To determine the tie lines connecting the binodal curves in the toluene-water-acetonesystem.

APPARATUS:

1. Separating funnels for settling and separating the mixtures.2. Conical flasks, measuring cylinders, and standard laboratory apparatus.

3. Refractometer.

PROCEDURES:

1. Obtain the calibration curve from Appendix C.1.

2. Record the average ambient temperature throughout the experiment and obtain thepure component densities for acetone, water and toluene at the experimenttemperature.

3. Prepare 6 heterogeneous mixtures of acetone, toluene and water in 6 different conicalflasks according to the compositions recommended in the table in Appendix E.

4. Agitate the mixtures for about 60 minutes.

Note: To prevent emulsification, do not agitate the mixtures too vigorously.

5. Pour each of the mixture into a separating funnel. Let the mixture settle into two distinct


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APPENDIX D

SAMPLE TABLES FOR APPENDIX C.1

Toluene Rich Phase

No

Amount in mixture (mL) Wateradded(mL)

Composition (wt%)Refractive

indexAcetone Toluene Acetone Water Toluene

1 160 mL 40 mL

2 140 mL 60 mL

3 120 mL 80 mL

4 100 mL 100 mL

5 80 mL 120 mL

6 60 mL 140 mL


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APPENDIX E

SAMPLE TABLE FOR APPENDIX C.2

No.

Amount in mixture (mL) Water rich phase Toluene rich phase

Acetone Water TolueneRefractive

index

Acetonecomposition

(wt%)

Refractiveindex

Acetonecomposition

(wt%)

1 20 mL 90 mL 90 mL

2 40 mL 80 mL 80 mL

3 60 mL 70 mL 70 mL

4 80 mL 60 mL 60 mL

5 100 mL 50 mL 50 mL

6 120 mL 40 mL 40 mL


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APPENDIX F

TRIANGULAR PLOT FOR TERNARY DIAGRAM

acetone


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APPENDIX G

PHYSICAL PROPERTIES OF COMPONENTS

G.1 Physical Properties of Pure Components in the Ternary System

ComponentTemp(oC)

Density(kg/m3)

Viscosity(10-3 Pa.s)

SurfaceTension

(10-3 Nm-1)Refractive Index

Water 20 998.2 1.003 72.75 1.333

25 997.02 0.8903 72.58 1.332

Toluene 20 866.7 0.586 28.4 1.497

25 862.3 0.552 27.6 1.494

Acetone 20 790.5 0.322 23.4 1.359

25 784.4 0.304 23.2 1.356

Acetone (CH3COCH3) : A colourless, volatile, extremely flammable liquid, miscible with water,used as a solvent and reagent. Also known as 2-propanone.

Toluene (C6H5CH3) : A colourless, aromatic liquid derived from coal tar or from the catalyticreforming of petroleum naphthas; insoluble in water, soluble in alcohol


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G.2 Fire and Safety Properties

Property Acetone Toluene

Boiling Point (oC)

Melting Point (oC)

Flash Point (oC) – closed cup

Explosive Limits in Air

lower (% vol.)

upper (% vol.)

Ignition Temperature (oC)

Vapour Pressure @ 20 oC (mmHg)

56.5

-94.6

-19

2.6

12.8

538

185

110.4

-95

4

1.2

7.0

508

22


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G.3 Binodal Compositions for Acetone-Toluene-Water System

Acetone(wt%)

Toluene(wt%)

Water(wt%)

Acetone(wt%)

Toluene(wt%)

Water(wt%)

0.5 0.026 99.474 66 19 15

0 0.029 99.971 66 19.8 14.2

1 0.03 98.97 65.9 20.63 13.47

1.5 0.043 98.457 65.01 24.9 10.092.499 0.05 97.451 65 25 10

4.997 0.054 94.949 64.07 26.94 8.99

10 0.06 89.94 62.4 30.6 7

19.97 0.16 79.87 62.18 31.53 6.29

29.91 0.3 69.79 59.49 34.43 6.08

18.9 0.4 80.7 58.4 36.6 5

34.5 0.5 65 55.4 40.6 4

35.71 0.62 63.67 54.88 41.47 3.65

39.56 0.92 59.52 54.6 41.58 3.82

42 1 57 51.1 45.9 3

42.68 1.03 56.29 48.76 48.76 2.48

42.7 1.12 56.18 48.1 49.4 2.5


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G.4 Tie Line Compositions for Acetone-Toluene-Water System

Acetone Composition (wt%)

Water RichPhase

Toluene RichPhase

Water RichPhase

Toluene RichPhase

0.27 0.21 12.42 11.3

0.59 0.36 13.05 11.91

0.95 0.59 14.1 13.11.08 0.78 14.41 13.52

1.54 1.13 17.32 16.98

1.72 1.11 19.3 18.8

2.32 1.52 20 20.2

2.41 1.69 20.5 21.35

2.43 1.74 21.44 22.62

2.7 1.85 25.7 27.4

3.13 2.38 25.8 29.05

3.42 2.45 31.51 38.12

4.2 3.15 32 37.5

4.5 2.8 32.3 39.6

5.1 3.84 32.82 41.06


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APPENDIX H

TYPICAL CALIBRATION DATA

Determination Of The Binodal/Solubility Curve

Refractive index for pure acetone = 1.3581

Refractive index for pure water = 1.3332

Refractive index for pure toluene = 1.4954

Toluene Rich Phase

No

Amount in mixture (mL) Wateradded(mL)

Composition (wt%)Refractive

indexAcetone Toluene Acetone Water Toluene

1 12.7 104.1 2.5 9.79 2.42 87.78 1.4753

2 25.2 91.8 3.0 19.48 2.92 77.60 1.4649

3 54.0 64.6 4.1 41.61 3.97 54.42 1.4304

4 67.4 50.0 5.4 52.30 5.27 42.43 1.4147


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1.3300

1.3350

1.3400

1.3450

1.3500

1.3550

1.3600

1.3650

1.3700

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70

R I

Acetone composition (wt%)

Calibration Curve for Water Rich Phase

®


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Binodal/Solubility Curve on the Triangular Diagram

acetone


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0

10

20

30

40

50

60

70

80

0 5 10 15 20 25 30 35 40 45 50 55 60

A c e t o n e c o m p o

s i t i o n i n t o l u e n e r i c h p h a s e ( w t % )

Acetone composition in water rich phase (wt%)

Tie Line Compositions



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APPENDIX I: RESULTS

EXPERIMENT 1

RunNo.

Feed flowrate

(L/min)

Solventflowrate

(L/min)

Solvent tofeed ratio

Time(min)

Raffinate Extract

HETP(mm)

Separationefficiency

(%)Refractive

index

Solutecomposition

(wt%)

Refractiveindex

Solutecomposition

(wt%)

1 0.12 0.12 1:1 10 1.3341 1.4511

20 1.3342 1.4508

30 1.3354 1.4411

40 1.3358 1.4435

50 1.3363 1.4461

60 1.3371 1.4461

70 1.3363 5.0 1.4464 32.1 760 64.0

2 0.12 0.12 1:1 0 1.3369 1.4431

10 1.3373 1.4445

20 1.3374 1.4444

30 1.3371 7.0 1.4463 32.6 797 65.2

3 0.12 0.24 1:2 10 1.4098 1.339520 1.4121 1.3425

30 1.3422 1.4162

40 1.3413 1.4211



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50 1.3422 1.4631

60 1.3402 1.4655

70 1.3390 9.5 1.4651 19.5 889 39.0



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Composition Diagram for Run 1 Data



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=

=32.6%

50%

= 0.652

For Run 3 data:

= ℎ

.

=2000

2.25

= 889

=

=19.5%

50%

= 0.390



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EXPERIMENT 2: RECOVERY OF SOLVENT

POWER OF HEATER REFRACTIVE INDEX PURITY OF TOLUENE (%)

1000 W 1.4850 90

2000 W 1.4901 93

liquid liquid extraction unit

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