kmps extraction 1
DESCRIPTION
extractionTRANSCRIPT
Liquid-Liquid Extraction
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
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
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
Removal of Organics From WaterDistillation vs. Extraction
Organic Compound BP [°C] Water Solu. [%]
AzeotropeB.P. [°C]
AzeotropeWater [%]
Typical Reduction Level
Methylene Chloride 40 2.0 38.1 1.5 < 50 ppbAcetone 56.2 Infinite Non Azeotropic < 50 ppbMethanol 64.5 Infinite Non Azeotropic < 50 ppbBenzene 80.1 0.18 69.4 8.9 < 50 ppbToluene 110.8 0.05 85.0 20.2 < 50 ppbFormaldehyde -21 Infinite Non Azeotropic < 1,000 ppmFormic Acid 100.8 Infinite 107.1 22.5 < 500 ppmAcetic Acid 118.0 Infinite Non Azeotropic < 500 ppmPyridine 115.5 57 92.6 43 < 10 ppmAniline 181.4 3.60 99.0 80.8 < 10 ppmPhenol 181.4 8.20 99.5 90.8 < 10 ppmNitrobenzene 210.9 0.04 98.6 88.0 < 10 ppmDinitrotoluene (2,4) 300.0 0.03 99 – 100 > 90 < 10 ppmDimethyl 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
Simple Extraction Single Stage
A – 99B – 0C – 1 100
Feed (F)
A – 0B – 50C – 0 50
Solvent (S)
A – 0B – 50C – 0.8 50.8
Extract (E)
A – 99.0B – 0C – 0.2 99.2
Raffinate (R)
4.07.929950MF
SE
7.9299
0.250
0.8
RaffinateinSoluteConc.ExtractinSoluteConc.M
0.21.00.2
FeedinSoluteRaffinateinSoluteU
Fraction Unextracted
Distribution Coefficient
Extraction Factor
Cross Flow Extraction
ARR11 RR22 RR33 RR44
C C C CF + S = M1 R1 + S = M2 R2 + S = M3 R3 + S = M4
A + B
F
B + C B + C B + C B + CE1 E
2
E3
E4
R1R2R3
R4
E1 E2 E3
E4
M1M2M3M4
B
A C
F
Countercurrent Flow Extraction
ARR11 RR22 RR33 RR44
A + B
F
B + CCE1
E2
E3
E4B + C B + C
B + C
F + S = ME1 + R4 = MF + S = E1 + R4
F – E1 = R4 – S =
Equations
C
R1
R2R3
R4
E1
B
A
F
M E2
E3E4
S
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
Bench Scale Test Apparatus
Variable Speed Drive
ThermometerBaffle
Tempered Water
In Drain
1 – Liter Flask
Tempered Water
Out
Simple Extraction
Graphical Graphical SolutionSolution
Y
X
YBE
YBS
XBR XBF
Equilibriu
m Curve ->
Slope = m
Operating Line ->
Slope = FI /S
I
m = YB* XB*
Distribution Coefficient on Solute Free Basis
Process Process SchemeScheme
NN
F
S
E
R
xAS
xBF
1.0
yAS
yBS
yCS
1.0xAR
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)
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 Fr
act.
, Sol
ute
Free
)
Raffinate Composition (Wt Fract., Solute Free)
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)Ex
trac
t C
ompo
siti
on (
Wt
Frac
t., S
olut
e Fr
ee)
Raffinate Composition (Wt Fract., Solute Free)
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
23
45
6
(0.136, 0.118)
Extr
act
Com
posi
tion
(W
t Fr
act.
, Sol
ute
Free
)
Raffinate Composition (Wt Fract., Solute Free)
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
E11
msy
nxm
syfx
LOG
n
Engineering CalculationsKremser Type Plot
1.00.80.6
0.40.3
0.2
0.10.080.06
0.040.03
0.02
0.010.0080.006
0.0040.003
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
ctio
n U
next
ract
ed
E = 0.3
E = 20
E = 1.3
XBR
F1
S1
E1
R1
YBS
XBF
YBE
E = Extraction FactorE = m (S1/F1)
Typical Extraction System
(A+B)
FeedA+B
C
A+(B+C)
B+C+(A)
A (B+C) B (C)
C(A)
C(A+B)
Extractio
Extractio
nn
Raffinate
Raffinate
StrippingStripping
Solvent Solvent
Recovery
RecoverySolvent
Removal of Phenol from Wastewater
ppb Phenol
Extractio
Extractio
nn
Raffinate
Raffinate
StrippingStripping
Solvent Solvent
Recovery
Recovery
Wastewater Feed
0.1 – 8 % Phenol
Raffinate
RecycledSolvent
Extract
PhenolBiological TreatmentBiological TreatmentOrOr
Carbon AdsorptionCarbon Adsorption
< 1 ppm Phenol
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
Raffinate
Raffinate
StrippingStripping
Solvent Solvent
Recovery
Recovery
Raffinate
RecycledSolvent
Extract
Acetic AcidAqueous Raffinate
Recovery of Carboxylic Acids from WastewaterUsing a High Boiling Point Solvent
Extractio
Extractio
nn
Dehydration
Dehydration
Solvent Solvent
Recovery
Recovery
Water Feed
0.1 – 5 % Mixed Acids
Acetic Acid99%+ Purity
Recovered Recovered SolventSolvent
Clean UpClean Up
Acid
Acid
Recovery
Recovery
Formic Acid99%+ PurityWater
Raffinate< 1,000 ppb Mixed Acids
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.
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
Recovery of Caprolactam
Feed From
ReactionSection
Lactam
Oil
Lactam
Oil
Ext.
Ext.
AQ Waste AQ Waste to to
DischargeDischarge
Am
. Sulphate A
m. Sulphate
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
Phosphoric Acid Purification via Extraction
Extractio
Extractio
nn
Raffinate Raffinate to to
DisposalDisposal
Scrub Scrub
Extraction
Extraction
Re-
Re-
Extraction
Extraction
PhosphoriPhosphoric Acid to c Acid to RecoveryRecovery
Water
Solvent
Phosphate Phosphate Rock Rock
DigesterDigesterHCLHCL
Feed
Recycle
Scrub Solv.
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
Fractional ExtractionProcess Scheme
XAS2,XBS2
XAF,XBF
XAS1,XBS1
YAE,YBE
XAR,XBR
I2S
I1F
I1S
IE
IR(B-Rich)
(A-Rich)
NNRR
NNSS
Extraction of Flavors andAromas
Oil Essential Extract
Extractio
Extractio
nn
Solvent 1 Solvent 1
Distillation
Distillation
Aqueous Alcohol
Solvent 2 Solvent 2
Distillation
Distillation
Essential Oil
Hydrocarbon
Typical Products: Orange Oil Lemon Oil Peppermint Oil Cinnamon Oil
Separation of StructuralIsomers
Typical Applications: m. p. - Cresol Xylenols 2 , 6 - Lutidine 3 , 4 - Picoline
Solvent 1 Solvent 1
Distillation
Distillation
Solvent 2 Solvent 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)
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
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
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
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
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)
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)
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
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
Scheibel Column Internal Assembly
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
Karr Column Plate Stack Assembly
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
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
PFKPFKPSEPSE
FKFKMSMS SESE
Effic
ienc
y / S
tage
s pe
r M
eter
Capacity M3/(M2 HR)
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:
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:
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
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
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
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
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
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
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”)
Continuous Extraction Pilot Plant Arrangement
Hot Oil
Feed Solvent
Variable Speed Drive
Raffinate
Extract
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
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
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
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
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
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
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
SOR OR11 22 33
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
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
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
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
Generalized Scale-up Procedure
Pilot ScalePilot Scale Commercial ScaleCommercial Scalef1
Q1
DD11
H1
Feed RateQ2
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
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
Scheibel Column Pilot Plant SetupNitrated Organics Extraction
Hot Oil
Spent Acid Feed
MCB Solvent
Aqueous Raffinate
Organic Extract
Interface
Variable Speed Drive
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
Scheibel Column Scale-up ProcedureNitrated Organics Extraction
Rat
e in
Com
mer
cial
Col
umn
For D
ia. ≥
18”
Rate in 3” Dia. Pilot ScheibelColumn
[GPH/FT2]
[GPH
/FT2 ]
157
530
Col
umn
Cap
acity
For D
ia. <
18”
Scheibel ColumnDiameter
[IN]
[GPH
/FT2 ]
600
100
300
5 10 15 20
14” Dia. = 430 GPH/FT2
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
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
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
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
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
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
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
Extraction Experience
KMPS has supplied over KMPS has supplied over 300 extraction columns300 extraction columns.
Questions?Questions?