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COUNTERCURRENT MULTISTAGE EXTRACTION (using supercritical fluids) What for?

Chapter 5. 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.

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COUNTERCURRENT MULTISTAGE EXTRACTION (using supercritical fluids) What for?

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  1. Chapter 5 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

  2. COUNTERCURRENT MULTISTAGE EXTRACTION 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

  3. Some Fatty Acids Linoleic acid C17H31COOH, MW: 280,44 Linolenic acid C17H29COOH, MW: 278,42 Arachidonic acid C19H31COOH, MW: 304,46

  4. Fatty Acid Content of Some Natural Materials Fatty acids in weight-percent Spezies -Linolenic acid EPA DPA DHA C18:3 C20:5 C22:5 C22:6 Plants Flax 50 --- --- --- Soya 8 --- --- --- Thistle 9 --- --- --- Algae Amphidinium carterri 0,1 7,4 0,6 25,4 Dunaliella primolecta 10,4 9,7 3,9 --- Cryptomonas sp. 7,0 16,0 --- 10,0 Fish Mackerel 1,48 14,16 2,82 10,26 Codfish 0,92 6,00 2,4 7,62 Sardine --- 18,08 2,16 10,25 Thuna fish --- 4,9 1,2 27,7 Herring 1,15 4,28 0,74 4,06

  5. Analysis and Pseudo Components of Fish Oil FA I Component Feed Gas phase Liquid phase KiPseudo- component [A-%] [A -%] [A -%] [-] C14:0 7,22 12,21 6,91 1,77 0,13 0,22 0,12 1,83 0,19 0,31 0,19 1,63 0,48 0,70 0,47 1,49 C14 C16:4n-1 2,89 3,84 2,83 1,36 1,73 2,28 1,69 1,35 C16:1n-7 9,17 11,82 8,98 1,32 C16:3n-3 1,12 1,45 1,10 1,32 0,38 0,48 0,38 1,26 C16:0 16,13 19,81 15,85 1,25 0,41 0,49 0,41 1,20 0,21 0,24 0,20 1,20 0,17 0,19 0,17 1,12 0,41 0,43 0,40 1,08 C16 0,13 0,12 0,12 1,00 0,33 0,33 0,33 1,00 C18:4n-3 3,12 3,09 3,11 0,99 1,44 1,39 1,44 0,97

  6. Analysis and Pseudo Components of Fish Oil FA II C18:1n-9 10,12 9,62 10,11 0,95 3,05 2,86 3,05 0,94 0,44 0,40 0,43 0,93 0,12 0,10 0,12 0,83 C18-0 3,17 2,81 3,17 0,89 C18 C20:4n-6 1,00 0,73 1,02 0,72 C20:5n-3 18,07 13,51 18,30 0,74 0,24 0,13 0,23 0,57 C20:4n-3 1,01 0,69 1,03 0,67 0,27 0,17 0,26 0,65 C20:1n-11 0,69 0,46 0,69 0,67 0,30 0,20 0,31 0,65 0,23 0,15 0,17 0,88 C20:0 0,22 0,14 0,23 0,61 C21:5n-3 0,74 0,49 0,76 0,64 C20 0,37 0,18 0,40 0,45 C22:6n-3 10,26 5,81 10,52 0,55 C22:4n-6 0,12 0,14 C22:5n-3 2,17 1,19 2,23 0,53 C22:1n-11 0,36 0,15 0,38 0,39 C22:0 0,09 0,09 C24:1 0,38 0,12 0,40 0,30 C22 99,08 99,31 98,74

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

  8. Triglycerides Fatty Acids Glycerol Triglycerides s

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

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

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

  12. Definition of Task • 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

  13. Limiting Phase Equilibrium Maximum concentration in a countercurrent process

  14. Phase equilibrium: PUFA - CO2

  15. Separation PUFA - CO2-Propane

  16. Separation factor for FAEE in sc CO2 14 MPa 333 K Separation factor  Ethyl ester in gas [wt.-%]

  17. P,x - Diagramm PUFA- Feed - CO2

  18. Density of Coexisting Phases % C20: EE1: 3.3 EE10: 91.6 EE 13: 9.5 + 90.5 % C 22

  19. Equilibrium Calculations: Fundamental Equation

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

  21. Equilibrium Calculations: Mixing Rule b,

  22. Separation factor: Concentration Dependence FA-ethyl esters - CO2 Riha 1996

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

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

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

  26. Mc- Cabe-Thiele Analysis Equilibrium

  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: nth or NTU Determine min. reflux, min. nth or NTU Vary reflux-ratio; Calculate separation as function of nth or NTU Calculate nth or NTU as function of separation Determine concentration profiles.

  34. Scheme of Stage Calculations

  35. Experimental Verfication in a Laboratory Plant

  36. PUFA - Separation: C16 - C18 Van Gaver

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

  38. HETP, HTU FA-ethyl esters - CO2 Riha 1996

  39. Kolonnenschaltung zur Gewinnung einer PUFA-Fraktion

  40. Separation routes for n3 fatty acids (as esters) Feed AgNO3 Urea Distillation SFE-Countercurrent Extraction EPA 92 wt.-% DHA 90 wt.-% EPA 44 wt.-% DHA 42 wt.-% EPA 73 wt.-% DHA 85 wt.-% Chromatographic Separation Processes, SFC EPA > 95 wt.-% DPA > 95 wt.-% DHA > 95 wt.-%

  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 THEORY Krukonis 1988

  44. Multistage cc separation of n3- FAEE THEORY Krukonis 1988

  45. Summary and Design Procedure 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)

  46. Summary and Design Procedure 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

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