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Liquid-Liquid Extraction

Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

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Page 1: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Liquid-Liquid Extraction

Page 2: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Hierarchy of Separation Technologies

Physical SeparationsDecantation, Coalescing, Filtration,

Demisting

EvaporationSingle Effect, Multiple Effect

DistillationSimple, Azeotropic, Extractive, Reactive

ExtractionSimple, Fractional, Reactive

AdsorptionPressure Swing, Temperature Swing

CrystallizationMelt, Solvent

MembranesMF, UF, NF, RO

Easy

Difficult

DifficultyDifficultyOf Of

SeparationSeparation

Page 3: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Typical Applications

• Remove products and pollutants from dilute aqueous streams

• Wash polar compounds or acids/bases from organic streams

• Heat sensitive products

• Non-volatile materials

• Azeotropic and close boiling mixtures

• Alternative to high cost distillations

Page 4: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Extraction is Used in a Wide Variety of Industries

Chemical •Washing of acids/bases, polar compounds from organics

Pharmaceuticals• Recovery of active materials from fermentation broths• Purification of vitamin products

Effluent Treatment• Recovery of phenol, DMF, DMAC• Recovery of acetic acid from dilute solutions

Polymer Processing• Recovery of caprolactam for nylon manufacture• Separation of catalyst from reaction products

Petroleum• Lube oil quality improvement• Separation of aromatics/aliphatics (BTX)

Petrochemicals• Separation of olefins/parafins• Separation of structural isomers

Food Industry• Decaffeination of coffee and tea• Separation of essential oils (flavors and fragrances)

Metals Industry• Copper production• Recovery of rare earth elements

Inorganic Chemicals • Purification of phosphoric acid

Nuclear Industry • Purification of uranium

Page 5: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Removal of Organics From WaterDistillation vs. Extraction

Organic Compound BP [°C]Water

Solu. [%]Azeotrope

B.P. [°C]

Azeotrope

Water [%]Typical

Reduction Level

Methylene Chloride 40 2.0 38.1 1.5 < 50 ppb

Acetone 56.2 Infinite Non Azeotropic < 50 ppb

Methanol 64.5 Infinite Non Azeotropic < 50 ppb

Benzene 80.1 0.18 69.4 8.9 < 50 ppb

Toluene 110.8 0.05 85.0 20.2 < 50 ppb

Formaldehyde -21 Infinite Non Azeotropic < 1,000 ppm

Formic Acid 100.8 Infinite 107.1 22.5 < 500 ppm

Acetic Acid 118.0 Infinite Non Azeotropic < 500 ppm

Pyridine 115.5 57 92.6 43 < 10 ppm

Aniline 181.4 3.60 99.0 80.8 < 10 ppm

Phenol 181.4 8.20 99.5 90.8 < 10 ppm

Nitrobenzene 210.9 0.04 98.6 88.0 < 10 ppm

Dinitrotoluene (2,4) 300.0 0.03 99 – 100 > 90 < 10 ppm

Dimethyl Formamide

153.0 Infinite Non Azeotropic < 10 ppm

Dimethyl Acetamide

166.1 Infinite Non Azeotropic < 10 ppm

n-Methylpyrrolidone

202.0 Infinite Non Azeotropic < 10 ppm

Ext

ract

ion

Ext

ract

ion

Dis

tilla

tion

Dis

tilla

tion

Page 6: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Simple Extraction Single Stage

A – 99

B – 0

C – 1

100

Feed (F)

A – 0

B – 50

C – 0

50

Solvent (S)

A – 0

B – 50

C – 0.8

50.8

Extract (E)

A – 99.0

B – 0

C – 0.2

99.2

Raffinate (R)

4.07.929950MF

SE

7.92

990.2

500.8

RaffinateinSoluteConc.

ExtractinSoluteConc.M

0.21.0

0.2

FeedinSolute

RaffinateinSoluteU

Fraction Unextracted

Distribution Coefficient

Extraction Factor

Page 7: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Cross Flow Extraction

ARR11 RR22 RR33 RR44

C C C C

F + S = M1 R1 + S = M2 R2 + S = M3 R3 + S = M4

A + B

F

B + C B + C B + C B + C

E1 E2

E3

E4

R1R2

R3

R4

E1E2

E3

E4

M1

M2M3M4

B

A C

F

Page 8: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Countercurrent Flow Extraction

ARR11 RR22 RR33 RR44

A + B

F

B + CC

E1

E2

E3

E4B + C B + C

B + C

F + S = ME1 + R4 = MF + S = E1 + R4

F – E1 = R4 – S =

Equations

C

R1

R2

R3

R4

E1

B

A

F

M E2

E3E4

S

Page 9: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Countercurrent Extraction

B + C

A

C

A + BFeed (F)

Solvent (S)

Extract (E):Solute Rich Stream

Raffinate (R):Solute Lean Stream

Primary Interface

Continuous Phase

Dispersed Phase

Page 10: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Bench Scale Test Apparatus

Variable Speed Drive

ThermometerBaffle

Tempered Water

In Drain

1 – Liter Flask

Tempered Water

Out

Page 11: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Simple Extraction

Graphical Graphical SolutionSolution

Y

X

YBE

YBS

XBR XBF

Equilibriu

m C

urve

-> S

lope

= m

Operatin

g Line -> S

lope = FI

/SI

m = YB* XB*

Distribution Coefficient on Solute Free Basis

Process Process SchemeScheme

NN

F

S

E

R

xAS

xBF

1.0

yAS

yBS

yCS

1.0

xAR

xBR

xCR

1.0

yAE

yBE

yCE

1.0

Solute Free Solute Free BasisBasis

NN

FI

SI

EI

RI

XBF = xBF

xAF

YBS = yBF

yAS+ yCS

YBE = yBE

yAR+ yCE

XBR = xBR

xAR+ xCR

FI=F(xAR)SI=S(yAS+yCS)EI=E(yAE+yCE)RI=R(xAR+xCR)

Page 12: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Typical LLE Equilibrium Curve

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.000 0.005 0.010 0.015 0.020

Extr

act

Com

posi

tion

(W

t F

ract.

, S

olu

te

Fre

e)

Raffinate Composition (Wt Fract., Solute Free)

Page 13: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Graphical Determination of Theoretical Stages95% Solute Extraction, S/F = 1.0 mass basis

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.000 0.020 0.040 0.060 0.080 0.100 0.120

1

2

3

(0.136, 0.114)

Extr

act

Com

posi

tion

(W

t F

ract.

, S

olu

te

Fre

e)

Raffinate Composition (Wt Fract., Solute Free)

Page 14: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Graphical Determination of Theoretical Stages98% Solute Extraction, S/F = 1.0 mass basis

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.000 0.020 0.040 0.060 0.080 0.100 0.120

1

2

3

4

56

(0.136, 0.118)

Extr

act

Com

posi

tion

(W

t F

ract.

, S

olu

te

Fre

e)

Raffinate Composition (Wt Fract., Solute Free)

Page 15: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Kremser Equation

Where: n = Number of theoretical stages requiredxf = Conc. of solute in feed on solute free basisxn = Conc. of solute in raffinate on solute free basisys = Conc. of solute in solvent on solute free basism = Distribution coefficientE = Extraction factor = (m)(S/F)

ELOG

E1

E1

1

msy

nx

msy

fx

LOG

n

Page 16: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Engineering CalculationsKremser Type Plot

1.00.8

0.6

0.4

0.3

0.2

0.10.080.06

0.040.03

0.02

0.010.0080.006

0.004

0.003

0.002

0.0010.00080.00060.0005

1 2 3 4 5 6 7 8 10 15 20

Number of Ideal Stages

XB

R/X

BF =

Fra

cti

on

Un

extr

acte

d

E = 0.3

E =

20

E = 1.3

XBR

F1

S1

E1

R1

YBS

XBF

YBE

E = Extraction FactorE = m (S1/F1)

Page 17: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Typical Extraction System

(A+B)

Feed

A+B

C

A+(B+C)

B+C+(A)

A (B+C) B (C)

C(A)

C(A+B)

Extractio

Extractio

nn

Raffin

ate R

affinate

Strip

pin

gS

tripp

ing

Solven

t S

olvent

Recovery

Recovery

Solvent

Page 18: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Removal of Phenol from Wastewater

ppb Phenol

Extractio

Extractio

nn

Raffin

ate R

affinate

Strip

pin

gS

tripp

ing

Solven

t S

olvent

Recovery

Recovery

Wastewater Feed

0.1 – 8 % Phenol

Raffinate

RecycledSolvent

Extract

PhenolBiological TreatmentBiological Treatment

OrOr

Carbon AdsorptionCarbon Adsorption

< 1 ppm Phenol

Page 19: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Recovery of Acetic Acid from WaterUsing a Low Boiling Solvent

Aqueous Feed

20 - 40 % Acetic Acid

Typical Solvents: Ethyl Acetate Butyl Acetate

Extractio

Extractio

nn

Raffin

ate R

affinate

Strip

pin

gS

tripp

ing

Solven

t S

olvent

Recovery

Recovery

Raffinate

RecycledSolvent

Extract

Acetic AcidAqueous Raffinate

Page 20: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Recovery of Carboxylic Acids from WastewaterUsing a High Boiling Point Solvent

Extractio

Extractio

nn

Deh

ydration

Deh

ydration

Solven

t S

olvent

Recovery

Recovery

Water Feed

0.1 – 5 % Mixed Acids

Acetic Acid99%+ Purity

Recovered Recovered SolventSolvent

Clean UpClean Up

Acid

A

cid

Recovery

Recovery

Formic Acid99%+ PurityWater

Raffinate< 1,000 ppb Mixed Acids

Page 21: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Neutralization/Washing of Acid or Baseor Polar Compounds from Organic Stream

Extractio

Extractio

nn

Water

Water + Salts

Organic

Caustic (Mild)**

Feed (Organic + Acid) **

** Organic Feed could contain caustic. Mid- Feed would be mild acid.

Page 22: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Series Extraction

Extractor

Extractor

#1#1

Extractor

Extractor

#2#2

Feed

A + B

Extract

B + C

Solvent 1

C Solvent 2

D

ProductB + D

RaffinateA

Extractor 1 & 2 May Differ By: - Temperature - pH - Solvent

Page 23: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Recovery of Caprolactam

Feed From

ReactionSection

Lactam

Oil

Lactam

Oil

Ext.

Ext.

AQ Waste AQ Waste to to

DischargeDischarge

Am

. Su

lph

ate A

m. S

ulp

hate

Ext.

Ext.

Am. Sulph. Am. Sulph. Waste to Waste to

DischargeDischarge

Re-

Re-

Extraction

Extraction

Lactam Oil Lactam Oil to to

RecoveryRecovery

WaterLactam Oil Phase65 – 70% Caprolactam

Ammonium Sulphate Phase2 – 3% Caprolactam

Extract

RaffinateSolvent

Page 24: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Phosphoric Acid Purification via Extraction

Extractio

Extractio

nn

Raffinate Raffinate to to

DisposalDisposal

Scru

b

Scru

b

Extraction

Extraction

Re-

Re-

Extraction

Extraction

PhosphoriPhosphoric Acid to c Acid to RecoveryRecovery

Water

Solvent

Phosphate Phosphate Rock Rock

DigesterDigesterHCLHCL

Feed

Recycle

Scrub Solv.

Page 25: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Organo-Metallic Catalyst Recovery

Extractio

Extractio

nn

Feed

Makeup Makeup OrganicOrganic

CatalystCatalystPreparationPreparation

ReactorReactor

SeparatorSeparator

Water Effluent(1 ppm Cobalt)

Water Effluent(200 ppm Cobalt)

Cobalt

Organo-MetallicCatalyst

Product

Slipstream

Organic

Page 26: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Fractional ExtractionProcess Scheme

XAS2,XBS2

XAF,XBF

XAS1,XBS1

YAE,YBE

XAR,XBR

I2S

I1F

I1S

IE

IR(B-Rich)

(A-Rich)

NNRR

NNSS

Page 27: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Extraction of Flavors andAromas

Oil Essential Extract

Extractio

Extractio

nn

Solven

t 1 S

olvent 1

Distillation

Distillation

Aqueous Alcohol

Solven

t 2 S

olvent 2

Distillation

Distillation

Essential Oil

Hydrocarbon

Typical Products: Orange Oil Lemon Oil Peppermint Oil Cinnamon Oil

Page 28: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Separation of StructuralIsomers

Typical Applications: m. p. - Cresol Xylenols 2 , 6 - Lutidine 3 , 4 - Picoline

Solven

t 1 S

olvent 1

Distillation

Distillation

Solven

t 2 S

olvent 2

Distillation

Distillation

Extractio

Extractio

nn

Mixed

IsomerFeed

Isomer 1

Extractio

Extractio

nn

Isomer 2

pH Adjust(Optional)

Reflux

Solvent 1 Recycle Solvent 2 Recycle

AqueousRaffinate

AqueousRecycle

pH Adjust(Optional)

Page 29: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Major Types of Extraction Equipment

Column Column ContactorsContactors

Mixer Mixer SettlersSettlers CentrifugalCentrifugal

Used primarily in the metals industry due to: - Large flows - Intense mixing - Long Residence time - Corrosive fluids - History

Used primarily in thepharmaceutical industry due to: - Large flows - Intense mixing - Long Residence time - Corrosive fluids - History

StaticStatic AgitatedAgitated

SpraySpray PackedPacked TrayTray PulsedPulsed RotaryRotary

ReciprocatinReciprocatingg

Rarely used Used in: - Refining - Petrochemicals

Example: - Random - Structured - SMVPTM

Used in: - Refining - Petrochemicals

Example: - Sieve

Used in: - Nuclear - Inorganics - Chemicals

Example: - Packed - Tray - Disc & Donut

Example: - RDC - Scheibel

Example: - Karr

Used in: - Chemicals - Petrochemicals - Refining - Pharmaceutical

Page 30: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Mix / Decant Tank

CharacteristicsCharacteristics• Mix – Settle – Phase separate in a single

tank

• Batch Processing only

• Requires multiple solvent additions for more than one stage (crossflow operation)

• Typically used for small capacity operations or intermittent processing

Feed Inlet

Outlet

Sight Glass

Page 31: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Mixer / Settlers

CharacteristicsCharacteristics

• Handle very high flowrates

• Good for processes with relatively slow reactions (residence time required)

• Provide intense mixing to promote mass transfer

• Require large amount of floor space

• Suitable when few theoretical stages required

• Large solvent inventory (and losses)

Light Phase In

Heavy Phase Out

Page 32: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Centrifugal Extractor

CharacteristicsCharacteristics• Countercurrent flow via centrifugal

force

• Low residence time ideally suited for some pharmaceutical applications

• Handles low density difference between phases

• Provide up to several theoretical stages per unit

• High speed device requires maintenance

• Susceptible to fouling and plugging due to small clearances

Page 33: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Packed Column

CharacteristicsCharacteristics• High capacity:

20-30 M3/M2-hr (Random) 500-750 gal/ft2-hr (Random) 40-80 M3/M2-hr (Structured) 1,000-2,000 gal/ft2-hr (Structured)

• Poor efficiency due to backmixing and wetting

• Limited turndown flexibility

• Affected by changes in wetting characteristics

• Limited as to which phase can be dispersed

• Requires low interfacial tension for economic usefulness

• Not good for fouling service

Feed (F)

Solvent (S)

Extract (E)

Raffinate (R)

Page 34: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Sieve Tray Column

CharacteristicsCharacteristics• High capacity: 30-50 M3/M2-hr

750-1,250 gal/ft2-hr

• Good efficiency due to minimum backmixing

• Multiple interfaces can be a problem

• Limited turndown flexibility

• Affected by changes in wetting characteristics

• Limited as to which phase can be dispersed

Feed (F)

Solvent (S)

Extract (E)

PrimaryInterface

Raffinate (R)

Page 35: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

RDC Extractor

CharacteristicsCharacteristics• Reasonable capacity:

20-30 M3/M2-hr

• Limited efficiency due to axial backmixing

• Suitable for viscous materials

• Suitable for fouling materials

• Sensitive to emulsions due to high shear mixing

• Reasonable turndown (40%)

VesselWalls

Shaft

Stators RotorsLightPhase In

HeavyPhase In

LightPhase Out

HeavyPhase Out

Drive Motor Gearbox

InterfaceControl

InterfaceInterface

Page 36: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Scheibel Column

CharacteristicsCharacteristics• Reasonable

capacity: 15-25 M3/M2-hr 350-600 gal/ft2-hr

• High efficiency due to internal baffling

• Good turndown capability (4:1) and high flexibility

• Best suited when many stages are required

• Not recommended for highly fouling systems or systems that tend to emulsify

LightPhase In

HeavyPhase In

LightPhase Out

HeavyPhase Out

Gearbox Variable SpeedDrive

InterfaceControl

InterfaceInterface

VesselWalls

RotatingShaft

TurbineImpeller

HorizontalInner Baffle

HorizontalOuter Baffle

Page 37: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Scheibel Column Internal Assembly

Page 38: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Karr Reciprocating Column

CharacteristicsCharacteristics• Highest capacity:

30-60 M3/M2-hr 750-1,500 gal/ft2-hr

• Good efficiency

• Good turndown capability (4:1)

• Uniform shear mixing

• Best suited for systems that emulsify

LightPhase Inlet

Sparger

HeavyPhase Inlet

Sparger

LightPhase Out

InterfaceInterface InterfaceControl

TeflonBaffle Plate

Tie Rods& Spacers

Center Shaft& Spacers

Spider Plate

PerforatedPlate

Metal BafflePlate

HeavyPhase Out

DriveAssembly

Seal

Page 39: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Karr Column Plate Stack Assembly

Page 40: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Pulsed Extractor

CharacteristicsCharacteristics• Reasonable capacity:

20-30 M3/M2-hr

• Best suited for nuclear applications due to lack of seal

• Also suited for corrosive applications since can be constructed out or non-metals

• Limited stages due to backmixing

• Limited diameter/height dueto pulse energy required

LightPhase In

HeavyPhase In

LightPhase Out

HeavyPhase Out

InterfaceControl

InterfaceInterface

TimerTimer

PulseLeg

SolenoidValves

CompressedAir

Exhaust

Air

Liquid

Page 41: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Comparison Plot of VariousCommercial Extractors

Graesser = Raining BucketMS = Mixer SettlerSE = Sieve PlateFK = Random PackedPFK = Pulsed PackedPSE = Pulsed Sieve PlateRDC = Rotating Disc ContactorRZE = Agitated CellKarr = Karr Recipr. PlateKuhni = Kuhni ColumnScheibel = Scheibel Column

Key

1 2 4 6 10 20 40 60 1000.2

0.4

.06

1

2

4

6

10

20ScheibelScheibel

KarrKarr

RDCRDC

GraesserGraesserKuhniKuhni

RZERZE

PFKPFK

PSEPSE

FKFK

MSMS SESE

Eff

icie

ncy

/ S

tag

es

per

Mete

r

Capacity M3/(M2 HR)

Page 42: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Column Selection CriteriaStatic Column

• Interfacial tension is low to medium: up to 10-15 dynes/cm

• Only a few theoretical stages are required, and reduction in S/F is not an economic benefit

• No operational flexibility required

• There is a large difference in solvent to feed rates

A static column design may be appropriate when:

Page 43: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Column Selection CriteriaAgitated Column

• More than 2-3 theoretical stages are required

• Interfacial tension is moderate to high, although low interfacial tensions may also be economical

• A reduction in solvent usage is beneficial to the process economics

• The process requires a wide turndown as well as the ability to handle a range of S/F ratios

Agitated columns are generally more economical when:

Page 44: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Column Selection CriteriaRotating Disc Contactor (RDC)

• Systems with moderate to high viscosity, i.e. > 100 cps

• Systems that are residence time controlled, for example, slow mass transfer rate with few theoretical stages required

• Systems with a high tendency towards fouling

Page 45: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Column Selection CriteriaScheibel Column

• Systems that require a large number of stages due to either theoretical stage requirements or low mass transfer rates

• Low volume applications in which a relatively small column is required

• Systems that process relatively easily, without a tendency to emulsify and/or flood

Page 46: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Column Selection CriteriaKarr Reciprocation Plate Column

• Difficult systems that tend to emulsify and/or flood easily

• Systems in which the hydraulic behavior varies significantly through length of the column

• Sometimes requiring non-metallic internals, such as Teflon due to wetting characteristics or corrosive materials

• Fouling applications that may have tars formations and/or solids precipitation

Page 47: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

The Three Cornerstones of Successful Extraction Applications

Successful Successful ApplicationApplication

Proper Proper Solvent Solvent

SelectionSelectionSelection Based on:

• Sound thermodynamic principles

• Sound economic principles

• Availability• Recoverability

• Sound environmental principles

• Toxicity• Safety

Meaningful Meaningful Pilot TestsPilot Tests

Accurate Accurate Scale-UpScale-Up

Testing Based on:

• Actual feed stocks

• Full process including solvent recovery

• Wide range of operating conditions

Scale-Up Based on:

• Proven techniques

• Proper safety factors

Page 48: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Organic Group InteractionsSolvent ClassSolvent Class

Solute ClassSolute Class 1 2 3 4 5 6 7 8 9 10 11 12

1 Phenol 0 0 - 0 - - - - - - + +

2 Acid, thiol 0 0 - 0 - - 0 0 0 0 + +

3 Alcohol, water - - 0 + + 0 - - + + + +

4 Active H on multihalogen 0 0 + 0 - - - - - - 0 +

5 Ketone, amide with no H on N, sulfone, phosphine oxide

- - + - 0 + + + + + + +

6 Tertiary amine - - 0 - + 0 + + 0 + 0 0

7 Secondary amine - 0 - - - + + 0 0 0 0 +

8 Primary amine, ammonia, amide, with 2H on N

- 0 - - + + 0 0 + + + +

9 Ether, oxide, sulfoxide - 0 + - + 0 0 + 0 + 0 +

10 Ester, aldehyde, carbonate, phosphate, nitrate, nitrite, nitrile

- 0 + - + + 0 + + 0 + +

11 Aromatic, olefin, halogen, aromatic multihalogen, paraffin without active H, manahalogen paraffin

+ + + 0 + 0 0 + 0 + 0 0

12 Paraffin, carbon disulfide + + + + + 0 + + + + 0 0

1 - 4 = H donor groups5 – 12 = H acceptor groups12 = Non-H bonding groups

Page 49: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Liquid-Liquid Extraction Scale-Up

• Theoretical scale-up is difficult

• Complexity of processes taking place within an extractor Droplet Breakup Coalescence Mass Transfer Axial and radial mixing Effects of impurities

• Best method of design: Pilot testing followed by empirical scale-up

Page 50: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Pilot Plant Configuration

• Determine type of column to be used based on process considerations

• Use the same kind of equipment for the production unit

• Determine diameter and height of pilot column based on experienceType of ColumnType of Column DiameterDiameter HeightHeight

Packed 3” to 4” 3’ to 6’ per Theoretical Stage (TS)

Tray 4” to 6” 4’ to 5’ Trays per TS

Karr 1” 1’ to 3’ per TS

Scheibel 3” 3 to 6 Actual Stages per TS (Approx. 3” to 6”)

Page 51: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Continuous Extraction Pilot Plant Arrangement

Hot Oil

Feed Solvent

Variable Speed Drive

Raffinate

Extract

Page 52: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

KMPS Pilot Plant Services Group

KMPS maintains a pilot KMPS maintains a pilot plant dedicated to plant dedicated to extraction R & D and extraction R & D and applications testingapplications testing

Page 53: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Possible Extraction Column Configurations

Solvent is Light Solvent is Light PhasePhase

Solvent is Heavy Solvent is Heavy PhasePhase

F

S

E

R

Primary Interface

A + B

B + C

C

A

SolventSolventDispersedDispersed

F

S

E

R

Primary Interface

A + B

C

A

SolventSolventContinuousContinuous

B + C

Primary Interface

FA + B

SC

RA

SolventSolventDispersedDispersed

EB + C

Primary Interface

FA + B

SC

RA

SolventSolventContinuousContinuous

EB + C

Page 54: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Factors Effecting which Phase is Dispersed

Flow RateFlow Rate

• For Sieve Tray and Packed Columns – disperse the higher flowing phase

• For all other columns – disperse lower flowing phase

ViscosityViscosity

• For efficiency – disperse less viscous phase

• For capacity – disperse more viscous phase

Viscous drop

Diffusion rate inside the drop is inhibited by viscosity

Viscous continuous phase

Drop rise or fall will be inhibited

Page 55: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Factors Effecting which Phase is Dispersed

Surface WettingSurface Wetting

• Want the continuous phase to preferentially set the internals – this minimizes coalescence and therefore maximizes interfacial area.

Importance of maintaining dropletsImportance of maintaining dropletsAssume – 30% holdup of dispersed phase in 1 M3 of solution

Droplets coalesce. Interfacial area lost.

Droplets retain shape. Maximizes interfacial area.

Droplet Droplet Diameter Diameter

[ []]

Droplet Droplet Volume Volume

[M[M33]]

Number Number DropletsDroplets

Droplet Droplet SA [MSA [M22]]

Interfacial Interfacial Area Area

[M[M22/M/M33]]

100 0.3 7.16x1010 1.26x10-7 9022

300 0.3 2.65x109 1.13x10-6 2995

500 0.3 5.73x108 3.14x10-6 1796

Page 56: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Factors Effecting which Phase is Dispersed

Marangoni EffectMarangoni Effect

• Coalescence is enhanced by mass transfer from droplets continuous phase

A + B A + BC

A

A + B

C

C + B C + B

C

Mass Transfer DirectionMass Transfer Direction

Dispersed Continuous (d c)

• Droplets tend to coalesce

• Must be counteracted by additional energy

Continuous Dispersed (c d)

• Droplets tend to repel each other

• Less energy required to maintain dispersion

Page 57: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Interface Behavior

Actions to control unstable Actions to control unstable interfaceinterface

As extraction proceeds, interface normally grows in thickness and forms a “rag” layer that stabilizes at some thickness

If rag layer continues to grow, some action must be taken1. Rag Draw

Continuously withdraw a portion of the interface and pass through a filter to remove interfacial contamination

2. Reverse PhasesOften a stable interface can be controlled by reversing which phase is dispersed

Rag Layer

Light Phase Dispersed

Heavy Phase Dispersed

Growing Uncontrolled

Interface

11 22Filter

Page 58: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Entrainment

Entrainment involves carrying over a small portion of one phase out the wrong end of the column.

Entrainment is controlled by:1.) Increased settling time inside the column2.) Coalescer inside the column3.) Coalescer external to the column

E

F

R

S

E

R

F

S

F

S

E

R

E

R

F

S

OR OR11 22 33

Page 59: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Flooding

Flooding – the point where the upward or downward flow of the dispersed phase ceases and a second interface is formed in the column.

Flooding can be caused by:• Increased continuous phase flow rate which increases drag on

droplets

Primary Interfacef

F1

S

E

R

Primary Interfacef

F2

S

E

R

SecondInterface

F2 > F1

Page 60: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Flooding

Flooding can be caused by:• Increased agitation speed which forms smaller droplets which

cannot overcome flow of the continuous phase• Decreased interfacial tension – forms smaller drops – same effect as

increased agitation

Primary Interfacef1

F1

S

E

R

Primary Interfacef2

F2

S

E

R

SecondInterface

f2 > f1

Page 61: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Pilot Tests

f

F

S DD

HH

Static ColumnsStatic Columns(Packed, Tray)

F

S DD

HH

Agitated ColumnsAgitated Columns(Scheibel, Karr)

N, S/FD, H(F+S)

N, S/FD, H

(F+S),f

Process FactorsColumn Variable

Variable

F+S

HETSFlood

f

HETS

F+S

F+S

MINHETS

Page 62: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Extractor Flow Patterns

Ideal Plug FlowIdeal Plug Flow Actual FlowActual Flow

This “axial” or “back” mixing causes concentration gradients that decrease

driving force and therefore increase HETS

Y

X

Y

X

Page 63: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Generalized Scale-up Procedure

Pilot ScalePilot Scale Commercial ScaleCommercial Scalef1

Q1

DD11

H1

Feed Rate

Q2

Feed Rate

f2

DD22

H2

Basic Scale-up Relationships:D2/D1 = K1(Q2/Q1 )^M1

H2/H1 = K2(D2/D1 )^M2

f2/f1 = K3(D2/D1)^M3 Where: K1, M1 = Capacity Scale-up Factors K2, M2 = Efficiency Scale-up Factors K3, M3 = Power Scale-up Factors

Page 64: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Application – Scheibel Column

• Extraction of nitrated organics from spent acid stream using an organic solvent

• Reduce nitrated organic compounds from 3.9% to less than 50 ppm

• S/F ratio fixed by process at 3.9

• Equilibrium data indicated that 4.5 theoretical stages required

• Commercial design: 3,900 lb/hr (270 GPH) spent acid feed

Page 65: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Scheibel Column Pilot Plant SetupNitrated Organics Extraction

Hot Oil

Spent Acid Feed

MCB Solvent

Aqueous Raffinate

Organic Extract

Interface

Variable Speed Drive

Page 66: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Scheibel Column Pilot Plant Test ResultsNitrated Organics Extraction

1160078235380369

15600701853003610

13650831853003611

32860084185300183

77650080185300182

15960091235380185

96350043235380184

14870074235380187

56350073235380186

54

78

82

Column Column Temp [°C]Temp [°C]

600

500

400

Agitation Agitation Speed Speed [RPM][RPM]

471502403612

16235380368

856185300181

Raffinate - Nit. Raffinate - Nit. Org. Conc. Org. Conc.

[PPM][PPM]

MCB Feed MCB Feed [cc/min][cc/min]

Acid Feed Acid Feed [cc/min][cc/min]

# of # of StagesStages

RunRun

Page 67: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Scheibel Column Scale-up ProcedureNitrated Organics Extraction

Rat

e in

Co

mm

erc

ial

Co

lum

nF

or

Dia

. ≥

18”

Rate in 3” Dia. Pilot ScheibelColumn

[GPH/FT2]

[GP

H/F

T2]

157

530

Co

lum

n C

apac

ity

Fo

r D

ia.

< 1

8”Scheibel Column

Diameter

[IN]

[GP

H/F

T2]

600

100

300

5 10 15 20

14” Dia. = 430 GPH/FT2

Page 68: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Scheibel Column Pilot Plant Scale-upNitrated Organics Extraction

• Diameter = 14” (D1)

• Expanded Head Diameter = 20” (D2)

• Bed Height = 9’-6” (A)

• Overall Height = 16’-4” (B)

A

D1

D2

B

Page 69: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Application – Karr Column Alcohol Extraction from Acrylates

• Extraction of methanol from an acrylate stream using water as the solvent

• Reduce methanol from 2.5% to less than 0.1%

• S/F ratio specified by client as 0.32 wt. basis

• Equilibrium data: distribution coefficient generated by KMPS, with average value of 5.3

• Commercial design: 36,900 lb/hr (4,660 GPH) acrylate feed

Page 70: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Karr Column Pilot Plant SetupAlcohol Extraction from Acrylates

Hot Oil

Water Feed

Acrylate Feed (methyl or ethyl)

Extract(H2O + Alcohol)

Raffinate(Acrylate Phase)

Interface

Variable Speed Drive

Karr ColumnKarr Column

1” Dia. x 8’ Plate StackPlate Spacing from Top: 6’ of 2” 1’ of 4” 1’ of 6”316SS Shaft, Plates & Spacers

Page 71: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Karr Column Pilot Plant Test ResultsMethanol Extraction from Acrylate

RunRun Plate Plate StackStack

Feed Rate Feed Rate [cc/min][cc/min]

Water Feed Water Feed Rate Rate

[cc/min][cc/min]

Agitator Agitator Speed Speed [SPM][SPM]

InterfaceInterface Raffinate Raffinate Conc. Conc.

AlcoholAlcohol

Raffinate Raffinate Conc. Conc. WaterWater

1 1 150 45 100 Bottom 0.124 2.55

2 1 150 45 75 Bottom 0.165 2.83

3 2 150 45 110 Bottom 0.169 2.78

4 2 150 45 140 Bottom 0.112 2.72

5 2 180 54 100 Bottom 0.203 2.90

6 2 180 54 125 Bottom 0.146 3.08

7 2 180 54 150 Bottom 0.118 2.66

8 2 180 54 200 Bottom 0.078 2.73

9 2 210 63 175 Bottom 0.084 2.65

Notes:Notes: Karr column with 1” dia. X 6’ plate stack height. Plate stack #1 is constant 2” plate spacing. Plate stack #2 has variable spacing, from top: 4’ of 2”, 1’ of 4”, 1’ of 6” spacing. Feed is acrylate with approximately 2.5% methanol

Page 72: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Karr Column Pilot Plant Scale-up ProcedureMethanol Extraction from Acrylate

• Select optimal run from test results

* Run 8:Feed Rate = 150 cc/minSolvent Rate = 45 cc/minSpecific Throughput (Q) = 560 GPH/FT2

• Production column design

* Diameter – direct scale-up based on specific throughput

* Height – HCOMM = ƒ(H)PILOT

* Agitation Speed – SPMCOMM = ƒ(SPM)PILOT

Page 73: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Karr Column Pilot Plant Scale-up ProcedureMethanol Extraction from Acrylate

• HCOMM = (DCOMM / DPILOT)0.38 x HPILOT

• HCOMM = (45/1)0.38 x (6 feet) = 26 feet

• SPMCOMM = (DPILOT / DCOMM)0.14 x SPMPILOT

• SPMCOMM = (1/45)0.14 x (200 SPM) = 117 SPM

• Where:

* HCOMM = Height Commercial Column

* HPILOT = Height Pilot Column

* DCOMM = Diameter Commercial Column

* DPILOT = Diameter Pilot Column

* SPMCOMM = Commercial Strokes Per Minute

* SPMPILOT = Pilot Strokes Per Minute

Page 74: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Karr Column Pilot Plant Scale-upMethanol Extraction from Acrylate

• Diameter = 45” (D1)

• Expanded Head Diameter = 68” (D2)

• Plate Stack = 26’-0” (A)

• Overall Height = 36’-8” (B)

A D1

D2

B

Page 75: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Extraction Experience

KMPS has supplied over KMPS has supplied over 300 extraction columns300 extraction columns.

Page 76: Liquid-Liquid Extraction. Hierarchy of Separation Technologies Physical Separations Decantation, Coalescing, Filtration, Demisting Evaporation Single

Questions?Questions?