DESIGN OF ABSORPTION COLUMN

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DESIGN OF KARR EXTRACTORPRESENTED BY: GROUP # 04 WALEED SHAHID (UW-13-Ch.E-BSC-10) MOHSIN RAZA (UW-13-Ch.E-BSC-18) HASEEB IQBAL (UW-13-Ch.E-BSC-21) SAEED (UW-13-Ch.E-BSC-23) ALI HASSAN (UW-13-Ch.E-BSC-31) M. FAHAD (UW-13-Ch.E-BSC-52) 2

MUHAMMAD FAHAD (UW-13-CH.E-BSC-052)3

DESIGN PROBLEMThe extractor is designed to separate a solution of methylene chloride and methanol with the input mass flow rates of 2185 lb/h (991 kg/h) and 33 lb/h (15.0 kg/h) respectively, using water as selective solvent with a mass flow rate of 2218 lb/h (995 kg/h) to recover 95% methanol. Calculate the diameter and height of the given system.

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LIQUID-LIQUID EXTRACTIONLiquid-liquid extraction is a mass transfer operation in which a solution (feed: mixture of solute and carrier liquid) is brought into intimate contact with an immiscible or slightly miscible liquid (selective solvent) in order to achieve transfer of the solute from the feed to the solvent. The two liquid phases that have different densities are then separated.5

STEPS USED DURING LIQUID-LIQUID EXTRACTIONBringing the feed and the solvent into intimate contact by dispersing one phase into the other as droplets.Separation of the extract and the Raffinate phases that have different densities.Removal and recovery of the solute from the extract phase in relatively pure form (by evaporation, crystallization, etc.).Removal and recovery of the solvent from each phase, usually by distillation.

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LLE Vs. DISTILLATIONDISTILLATIONLLEPhase creation is achieved through Heat.No heat required.Vapor and liquid are chemically similar.Phases are chemically different.Used for liquids having large volatility difference. Separation on the basis of boiling point.Used for liquids having low or negligible volatility difference.It is an expensive method of separation.Relatively cheaper.

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M.WALEED SHAHID(UW-13-CH.E-BSC-010)8

ADVANTAGES AND DISADVANTAGESADVANTAGESDISADVANTAGESLiquid-liquid extraction can be used in the separation of azeotropes. Can be time consuming, especially if attainment of equilibrium is slowIt can be operated at low to moderate temperature for recovery of heat sensitive productsCan be affected by small impurities in the solvent(s).LLE is cheaper and can be used instead of using the chemical methods.Cumbersome for a large number of samples or for large samples.It has rapid and very selective separations that are usually highly efficient.Formation of emulsions can interfere with the phase-separation processAlso used for components that have close boiling pointsCounter-current process can be complicated and can require complicated equipment

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APPLICATIONSExtraction of Fermentation Broth by using Karr Reciprocating-Plate Extractor.Extraction of Penicillin in Karr Reciprocating-Plate Extractor.Use of Ionic Liquid in a Karr Reciprocating-Plate Extractor.Recovery of tightly hydrogen-bonded organics from water; such as formaldehyde, formic acid and acetic acid.Removal of high boiling organics from wastewater; such as phenol, aniline and nitrated aromaticsEssential oil extraction; such as pharmaceuticals, flavors, fragrances and food products.Such as acrylates, nitrated organics and chloro-benzene compounds.

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LIQUID-LIQUID EXTRACTION EQUIPMENTThe equipment used to carry out the LLE are called Liquid-Liquid Extractors. Common extractors are divided into following classes:

11FLUID MOVEMENT MECHANICALLY AGITATEDSieve columnKARR columnPacked columnSCHEIBEL ColumnSpray columnPulsed columnMixer settlerRotating disk contractor

ALI HASSAN(UW-13-CH.E-BSC-031)12

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SIMPLE GUIDLINE FOR EXTRACTOR SELECTION ProcessMinimum residence timeEmulsifying tendencyFlow rate over 400 gal/min , minimum residenceSmall number of stages requiredNoNoNoNo

Centrifugal contractorReciprocating plate column , centrifugal contractorMixer settlerMixer settler (with out mechanical agitation)Mechanically agitated columnYesYesYesYes13

Principle of heat and mass transfer by binay k dutta13

SELECTION OF EQUIPMENTWe selected Karr Reciprocating-Plate Column for the given system, because it is suitable for the systems having intermediate to low interfacial tension and emulsifying tendency.

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they can handle systems that tend to emulsify and feeds that contain particulates. Surface tension of methylene chloride is 26.50mN/m. Water 72.80 mN/m methanol 22.70

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KARR RECIPROCATING-PLATE COLUMNThe Karr Reciprocating-Plate column is a descendent of the pulsed sieve-tray column. It has a reciprocating shaft with perforated plates mounted on it. In this column plates move up and down approximately 27 times per second. Also, the close spacing of the plates (2550 mm) promotes high turbulence and minimizes axial mixing, thus giving high mass-transfer rates and low HETS. The central shaft, which supports sets of plates, is reciprocated by a drive at the top of the column.15

Height equivalent of theoretical stage.

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KARR EXTRACTOR

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WORKING OF KARR EXTRACTOR

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SAEED AKHTAR(UW-13-CH.E-BSC-023)18

CASEThe extractor is designed to separate a solution of methylene chloride and methanol with the input mass flow rates of 2185 lb/h (991 kg/h) and 33 lb/h (15.0 kg/h) respectively, using water as selective solvent with a mass flow rate of 2218 lb/h (995 kg/h) to recover 95% methanol. Calculate the diameter and height of the given system.

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GIVEN DATAFeed:Methylene chloride = 2185 lb/hrMethanol = 33 lb/hrTotal = mF =2218 lb/hrRecovery coefficient = K = 2Methanol recovery % = =0.95Concentration mass unit= C = 0.5

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CONTINUED...Densities:Methylene chloride =82.41 Methanol = 48.7Water =62.4 x1 = mass fraction = 33/2218 = 0.0148

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DESIGNING STEPS FOR THE KARR EXTRACTORStep 1: Mass Fraction in RaffinateStep 2: Minimum Solvent Flow RateStep 3: Minimum Solvent Rate and Operating RateStep 4: Mass Fraction of Solute in ExtractStep 5: Calculation of Extraction Factor AEStep 6: Calculate the Number of Equilibrium StagesStep 7: Extractor Diameter22

SOLUTION

Step 1: Mass Fraction in RaffinateFor Finding the mass fraction in Raffinate we use following equation.

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CONTINUED...Step 2: Minimum Solvent Flow Rate

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CONTINUED...Step 3: Minimum Solvent Rate and Operating Rate

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CONTINUED...Step 4: Mass Fraction of Solute in Extract

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CONTINUED...Step 5: Calculation of Extraction Factor AE

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Step 6: Calculate the Number of Equilibrium Stages

CONTINUED...

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HASEEB IQBAL(UW-13-CH.E-BSC-021)DESIGN OF KARR EXTRACTOR29

CONTINUEDStep 7: Extractor Diameter and HeightFor calculation of extractor Height we require HETS As For HETS calculation, we require Diameter of extractor.As

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Interfacial Tension data Not available for our system so we switch to another method 30

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CONTINUED

Now we have to calculate Diameter of our system for which we calculate area, which is

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Volumetric throughput= Volumetric flow through a unit area as you are seeing from the units.32

CONTINUEDVolumetric Flow Rates of both Feed and Selective solvent.

Feed =

Selective Solvent

Area Volumetric Throughput

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For Feed we have firstly divided flow rate of solute with its density and then flow rate of solvent with its density and also done this for selective solvent33

CONTINUEDSo for our systemDiameterSo this calculated Diameter is less than 30 inch and we have standard pipe size of diameter 10.42 inch, so we use 10.42 inch pipe.

HETS

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Now, our diameter is less than 30 inches to be precise (8.37 inches) so we can select a standard size pipe rather than design one of exact measurements 34

CONTINUEDFor our design we increase value of HETS by 20% to avoid flooding.

Rounding off ZE to nearest 3

On both top and bottom we have installed settlers which have the diameter 50% greater than the extractor diameter and also height of each settler is equal to settler diameter.

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CONTINUEDDiameter of settler =Height of both settler =To join Extractor with settler we require reducers which are a foot long.Now reduces height =

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CONTINUEDApproximated height is:

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MOHSIN RAZA(UW-13-CH.E-BSC-018)38

EFFECT OF CONCENTRATION ON HEIGHT

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EFFECT OF RECOVERY % ON HEIGHT40

EFFECT OF CONCENTRATION ON HEIGHT41

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