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COUNTERCURRENT MULTISTAGE EXTRACTION (using supercritical fluids) What for? Separation of compounds, mostly liquid, of similar volatility Why supercritical.

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Presentation on theme: "COUNTERCURRENT MULTISTAGE EXTRACTION (using supercritical fluids) What for? Separation of compounds, mostly liquid, of similar volatility Why supercritical."— Presentation transcript:

1 COUNTERCURRENT MULTISTAGE EXTRACTION (using supercritical fluids) What for? Separation of compounds, mostly liquid, of similar volatility Why supercritical fluids? Low temperature Solvent free products Multistage countercurrent separation Better and new products Chapter 5

2 Example: Separation of n-3 Fatty acids derived from fish oil EPA C20 with 5 double bonds DHA C22 with 6 double bonds DPA C22 with 5 double bonds EPA: Eicosapentanoic acid DPA: Docosapentanoic acid DHA: Docosahexanoic acid COUNTERCURRENT MULTISTAGE EXTRACTION

3 Linoleic acid C 17 H 31 COOH, MW: 280,44 Linolenic acid C 17 H 29 COOH, MW: 278,42 Arachidonic acid C 19 H 31 COOH, MW: 304,46 Some Fatty Acids

4 Fatty acids in weight-percent Spezies  -Linolenic acid EPA DPA DHA C18:3 C20:5 C22:5 C22:6 PlantsFlax Soya Thistle AlgaeAmphidinium carterri0,1 7,4 0,625,4 Dunaliella primolecta10,4 9,7 3,9--- Cryptomonas sp.7,0 16, ,0 FishMackerel1,48 14,16 2,8210,26 Codfish0,92 6,00 2,4 7,62 Sardine--- 18,08 2,1610,25 Thuna fish--- 4,9 1,227,7 Herring1,15 4,28 0,744,06 Fatty Acid Content of Some Natural Materials

5 ComponentFeedGas phase Liquid phase K i Pseudo- component [A-%] [A -%][A -%] [-] C14:07,22 12,216,91 1,77 0,13 0,22 0,12 1,83 0,19 0,310,19 1,63 0,48 0,700,47 1,49 C14 C16:4n-12,89 3,842,83 1,36 1,73 2,281,69 1,35 C16:1n-79,17 11,828,98 1,32 C16:3n-31,12 1,451,10 1,32 0,38 0,480,38 1,26 C16:016,13 19,8115,85 1,25 0,41 0,490,41 1,20 0,21 0,240,20 1,20 0,17 0,190,17 1,12 0,41 0,430,40 1,08 C16 0,13 0,120,12 1,00 0,33 0,330,33 1,00 C18:4n-33,12 3,093,11 0,99 1,44 1,391,44 0,97 Analysis and Pseudo Components of Fish Oil FA I

6 C18:1n-910,12 9,6210,11 0,95 3,05 2,863,05 0,94 0,44 0,400,43 0,93 0,12 0,100,12 0,83 C18-03,17 2,813,17 0,89C18 C20:4n-61,00 0,731,02 0,72 C20:5n-318,07 13,51 18,30 0,74 0,24 0,130,23 0,57 C20:4n-31,01 0,691,03 0,67 0,27 0,170,26 0,65 C20:1n-110,69 0,460,69 0,67 0,30 0,200,31 0,65 0,23 0,150,17 0,88 C20:00,22 0,140,23 0,61 C21:5n-30,74 0,490,76 0,64C20 0,37 0,180,40 0,45 C22:6n-310,26 5,8110,52 0,55 C22:4n-60,120,14 C22:5n-32,17 1,192,23 0,53 C22:1n-110,36 0,150,38 0,39 C22:00,090,09 C24:10,38 0,120,40 0,30C22 99,08 99,3198,74 Analysis and Pseudo Components of Fish Oil FA II

7 Triglycerides P = Palmitic acid O = Oleic acid S = Stearic acid

8 Fatty Acids Glycerol Triglycerides Triglycerides s

9 Hydrolysis, Saponification Glycerolysis Methanolysis Interesteri- fication Reduction Transformation of Triglycerides

10 Countercurrent multistage processing Characteristics: Binary separation Reflux Enriching section Stripping section Supercritical solvent cycle

11 COMPOSITION OF PRODUCTS YIELD FEED QUANTITY COMPOSITION OF FEED PHASE EQUILIBRIA: (EXPERIMENT; CORRELATING) SEPARATION FACTORS Definition of the separation problem

12 COUNTERCURRENT MULTISTAGE EXTRACTION Determine: Number of theoretical stages (or number of transfer units). Height (Size) of a separation device Separation performance (Mass Transfer) Capacity of a separation device Throughput -----> diameter Definition of Task

13 Maximum concentration in a countercurrent process Limiting Phase Equilibrium

14 Phase equilibrium: PUFA - CO 2

15 Separation PUFA - CO 2 -Propane

16 Separation factor  Ethyl ester in gas [wt.-%] 14 MPa 333 K Separation factor for FAEE in sc CO 2

17 P,x - Diagramm PUFA- Feed - CO 2

18 % C20: EE1: 3.3 EE10: 91.6 EE 13: % C 22 Density of Coexisting Phases

19 Equilibrium Calculations: Fundamental Equation

20 Equilibrium Calculations: Cubic EOS (RK-type), Mixing Rule a

21 Equilibrium Calculations: Mixing Rule b,

22 FA-ethyl esters - CO 2 Riha 1996 Separation factor: Concentration Dependence

23 Design Methods For Number of Theoretical Stages McCabe-Thiele Analysis Ponchon-Savarit in a Jänecke-Diagram Simulation

24 Mass balances: Enthalpy balances: Equilibrium relations: Rate equations for mass transfer: CC-GE: Basic Equations

25 with: z = axial coordinate in the separation device; L i, V i = flow of component i in the liquid and gaseous phase; L, V = total flow of liquid and gaseous phase; H V, H L = enthalpy of gaseous and liquid phase; k Gi = mass transfer coefficient of component i, related to the gaseous phase; a = mass transfer area per volume of transfer device; P = total pressure; K i = equilibrium partition coefficient of component i between gaseous and liquid phase; V i * = equilibrium concentration of component i in the gaseous phase.

26 Equilibrium Mc- Cabe-Thiele Analysis

27 Minimum number of stages / mimimum reflux ratio Limiting conditions

28 PUFA - separation: n-min, v-min

29 Jänecke - diagram for sc solvent

30 Countercurrent- Extraction in a Jänecke - Diagram

31 PUFA - separation: Jänecke analysis

32 Separation Analysis

33 Simulation of the separation Select method: n th or NTU Determine min. reflux, min. n th or NTU Vary reflux-ratio; Calculate separation as function of n th or NTU Calculate n th or NTU as function of separation Determine concentration profiles.

34 Scheme of Stage Calculations

35 Experimental Verfication in a Laboratory Plant

36 Van Gaver PUFA - Separation: C16 - C18

37 Van Gaver PUFA- Separation: C18: sat. / unsaturated

38 FA-ethyl esters - CO 2 Riha 1996 HETP, HTU

39 Kolonnenschaltung zur Gewinnung einer PUFA- Fraktion

40 Feed Distillation SFE-Countercurrent Extraction AgNO 3 Urea EPA 44 wt.-% DHA 42 wt.-% EPA 73 wt.-% DHA 85 wt.-% EPA 92 wt.-% DHA 90 wt.-% Chromatographic Separation Processes, SFC EPA > 95 wt.-%DPA > 95 wt.-%DHA > 95 wt.-% Separation routes for n3 fatty acids (as esters)

41 Solexol - Process with near critical propane IEC 41:280, 1949

42 Multistage cc separation of n3- FAEE Krukonis 1988

43 Multistage cc separation of n3- FAEE Krukonis 1988 THEORY

44 Krukonis 1988 THEORY Multistage cc separation of n3- FAEE

45 SOLVING A MULTICOMPONENT SEPARATION IN CC-GE Define the mixture: components or pseudo-components Define the separation: identify key components, purity and recovery rate Determine separation performance: (as a function of reflux ratio): number of theoretical stages (n ) or number of transfer units (NTU) Summary and Design Procedure

46 Determine efficiency of mass transfer equipment: tray efficiency, or HETP, or HTU Determine limits for mass flow of countercurrent streams: maximum flow (entrainment, flooding) minimum flow (for effective mass transfer) Decide for a certain reflux ratio Calculate separation performance size of a column for the chosen equipment and operating conditions Summary and Design Procedure


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