31 - liquid-liquid extraction

LIQUID-LIQUID EXTRACTION

MODELS/APPLICATIONS

EQUILIBRIUM RELATIONSHIPS

• PHASE RULE FOR LLE

• VARIABLES INCLUDED– PRESSURE– TEMPERATURE– 4 COMPOSITIONS (2 IN EACH PHASE)

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LLE DIAGRAMS - FORMS

• LLE CAN BE PRESENTED IN VARIOUS FORMATS– TRIANGULAR, CARTESIAN,

McCABE-THIELE

Cehreli, S.; Bilgin, M, .Quaternary Liquid-Liquid Equilibrium of Water + Acetic Acid + Propionic Acid + Solvent (Amyl Alcohol, Cyclohexyl Acetate, or Toluene) Systems, J. Chem. Eng. Data; (Article); 2004; 49(5); 1456-1459.

OTHER LLE PLOTS

Kim, J.-K.; Park, D.-W., Liquid-Liquid Equilibrium for the Quaternary System Toluene + Water + Propionic Acid + Ethyl Acetate at 25 C and Atmospheric Pressure , J. Chem. Eng. Data; (Article); 2005; 50(2); 625-629

LLE PLOTS

Kim, J.-K.; Park, D.-W., Liquid-Liquid Equilibrium for the Quaternary System Toluene + Water + Propionic Acid + Ethyl Acetate at 25 C and Atmospheric Pressure , J. Chem. Eng. Data; (Article); 2005; 50(2); 625-629

LLE PLOTS• CARTESIAN SOLVENT-FREE PLOT

PERRY’S Ed. 7, PAGE 15-7

SINGLE STAGE LLX MODELS

• MASS BALANCES INCLUDE OVERALL AND COMPONENT

• NEED EQUILIBRIUM DATA TO CALCULATE EQUILIBRIUM CHANGES

• STAGE EFFICIENCY LESS THAN 100% RESULTS IN A CHANGE IN RELATIVE LOCATION OF xa VS xa* EMPLOYS LEVER RULE

SINGLE STAGE LLX MODELS• TYPICAL MODEL FOR PROCESS:

Pandit, P.; Basu, S., Dye and Solvent Recovery in Solvent Extraction Using Reverse Micelles for the Removal of Ionic Dyes , Ind. Eng. Chem. Res.; (Article); 2004; 43(24); 7861-7864.

MULTIPLE STAGE LLX MODELS

• MODEL USES OVERALL AND COMPONENT MASS BALANCES

• EQUILIBRIUM DATA USED INITIALLY TO DETERMINE MINIMUM SOLVENT (L/V) RATIO (PONCHON-SAVARITT)– LOCATES ya,min ON EXTENDED EQUILIBRIUM TIE

LINE PASSING THROUGH xa

– USE LEVER RULE TO DETERMINE Vb,min

• LOCALIZED EQUILIBRIUM VALUES CAN RESULT IN ACTUAL Vb,min VALUES BEING HIGHER AND THIS WILL BE NOTICED IN ACTUAL DESIGN IF Ncalc = ∞

MULTIPLE STAGE LLX MODELS

• SEQUENTIAL FEED – NORMALLY COUNTERCURRENT

Nishihama, S.; Hirai, T.; Komasawa, I., Separation and Recovery of Gallium and Indium from Simulated Zinc Refinery Residue by Liquid-Liquid Extraction , Ind. Eng. Chem. Res.; (Article); 1999; 38(3); 1032-1039.

MULTIPLE STAGE LLX MODELS

• DESIGN IS BASED ON RATIO OF Vb,act TO Vb,min

• USED TO LOCATE ya,act

• DESIGN POINT BASED IN INTERSECTION OF xa-ya LINE WITH xb-yb LINE.

• STAGES ARE STEPPED OFF BY ALTERNATING BETWEEN INTERSECTIONS ON EQUILIBRIUM ENVELOPE DEFINED BY EQUILIBRIUM TIE LINES AND LINES FROM DESIGN POINT.

MULTIPLE STAGE LLX MODELS

• McCABE THEILE DIAGRAM CAN BE CONSTRUCTED FROM DATA FROM PONCHON-SAVARITT

• ALTERNATELY, IF B & S ARE RELATIVELY IMMISCIBLE AND FLOWS ARE SPECIFIED, THEN INERT FLOW MODEL CAN BE USED FOR THE OPERATING LINE. USING COMPONENT BALANCES FOR SOLUTE, A:

MULTIPLE STAGE LLX MODELS• INERT FLOWS MODEL

• L' = NON-TRANSFERRING B IN RAFFINATE AND V' = NON-TRANSFERRING S IN EXTRACT.

• CAN BE PLOTTED WITH EQUILIBRIUM LINE ON McCABE-THIELE FOR CALCULATIONS

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LLX EQUIPMENT• MIXER-SETTLERS

A + B S

EXTRACT LAYER

RAFFINATE LAYER

EXTRACT

FAFFINATE

MIXER SETTLER

LLX EQUIPMENT

• SPRAY TYPE EXTRACTION TOWER

Chen, Liang-Huei (Chia-Nan Coll of Pharmacy and Science); Lee, Yuh-Lang, Effects of a surfactant on the mass transfer in spray-tower extraction column, Chemical Engineering Journal, v 73, n 1, 1999, p 77-81

SPRAY TYPE EXTRACTION TOWER

• USES A SPARGER FOR LIGHT LIQUID AND DISPERSER FOR HEAVY LIQUID

• OVERFLOW IS LIGHT/UNDERFLOW IS HEAVY

SIEVE TRAY EXTRACTION TOWER

• SIMILAR TO DISTILLATION UNIT

J. Antonio Rocha, J. Carlos Cardenas, Cesar Sosa, and Jorge Rosales, Preliminary design of sieve tray extraction columns. 1. Determination of the column diameter. Flooding velocities in sieve tray extractors , Ind. Eng. Chem. Res.; 1989; 28(12) pp 1873 - 1878

SIEVE TRAY EXTRACTION TOWER

• LIGHT LIQUID INVENTORIED UNDER EACH TRAY

• BUBBLES OF LIGHT LIQUID PASS THROUGH COUNTERFLOW OF HEAVY LIQUID

• DOWNCOMERS ARE USED TO TRANSFER HEAVY LIQUID DOWN THE COLUMN

SIEVE TRAY EXTRACTION TOWER

• DOWNCOMER DESIGN

J. Antonio Rocha, J. Carlos Cardenas, Cesar Sosa, and Jorge Rosales, Preliminary

design of sieve tray extraction columns. 1. Determination of the

column diameter. Flooding velocities in sieve tray extractors

, Ind. Eng. Chem. Res.; 1989; 28(12) pp 1873 - 1878

YORK-SHEIBEL COLUMN• YORK-SHEIBEL COLUMNUSES AGITATION TO

MIX MATERIAL FOR EACH STAGE WITH SETTLING OCCURING OUTSIDE THE AGITATION ZONE

PODBEILNIAK CENTRIFUGAL

• PROVIDES A SINGLE STAGE HIGH g CONTACTING

LIGHT OUTLIGHT IN HEAVY INHEAVY OUT

CONTACTINGREGIME

PROCESSES THAT UTILIZE LLX • TYPICALLY ARE THOSE IN WHICH DISTILLATION IS

NOT ECONOMICALLY ATTRACTIVE• SULFOLANE PROCESS (UOP) -RECOVERY OF

AROMATICS, COMBINES DISTILLATION WITH LLE

http://www.uop.com/

objects/55%20Sulfolan

e.pdf

PROCESSES THAT UTILIZE LLX

• BIOTECH AND BIOPHARM– SEPARATION OF HIGH MOLECULAR

WEIGHT FATTY ACIDS FROM VEGETABLE OILS

– PENICILLIN

Alfred Thomas, Fats and Fatty Oils, Ullmann's Encyclopedia of Industrial ChemistryCopyright © 2002 by Wiley-VCH Verlag GmbH & Co. KGaA

PENICILLIN PRODUCTION

PROCESS

Joseph A. Shaeiwitz, Joseph D. Henry, Jr.,

Biochemical Separations ,Ullmann's Encyclopedia of

Industrial ChemistryCopyright © 2002 by

Wiley-VCH Verlag GmbH & Co. KGaA

SUPERCRITICAL EXTRACTION

• SOLVENT IS AT SUPERCRITICAL CONDITIONS

• SUPERCRITICAL SOLVENT HAS THERMODYNAMIC AND TRANSPORT PROPERTIES THAT ARE SIMILAR TO A LOOSE LIQUID OR A DENSE GAS.– SOLUTE EXTRACTION BASED ON SOLUBILITY IN

SUPERCRITICAL PHASE– PRODUCT IS OBTAINED BY LETTING PRESSURE DOWN

TO SUBCRITICAL CONDITIONS• PROCESS DESCRIBED IN TEXT DECAFFINATION IS

MORE LIKE SUPERCRITICAL LEACHING

TYPICAL SC PROCESS

• Eldridge, R. B., Oil Contaminant Removal from Drill Cuttings by Supercritical Extraction, Ind. Eng. Chem. Res.; (Article); 1996; 35(6); 1901-1905.