1. Flow scheme of gas extraction from solids Chapter 3 Supercritical Fluid Extraction from Solids

2. Mechanisms of Transport in the Solid Phase

4. Elementary membrane Mechanisms of Transport in the Solid Phase

5. Model of an Elementary Membrane

6. Integral Extraction Curve

8. Extraction Rate Curves

9. Remaining amount of extract in the solid

10. Folie 10 Concentration of extract in SC-solvent

11. Caffeine from raw coffee beans, N 2 O Dependence of amount of extract on pressure

12. Caffeine from raw coffee beans, N 2 O Dependence of extraction rate on temperature

13. Caffeine from raw coffee beans, N 2 O Dependence of amount of extract on density

14. Caffeine from raw coffee beans, N 2 O Dependence of extraction on solvent ratio

15. Caffeine from raw coffee beans, N 2 O Dependence of extraction rate on solvent ratio

16. Caffeine from raw coffee beans, N 2 O Dependence of extraction rate on size of particles

17. Extraction of theobromine from cocoa seed shells Limited mass transfer by small particles

18. Extraction of oil from rape seeds Influence of pretreatment

19. Fluid phase (extract phase) Concentration of the extract:  accumulated quantity of extract;  quantity of extract per unit of time;  composition of extract in dependence of time. Concentration of the extract in the extraction vessel:  medium concentration over the total volume;  concentration in the extraction vessel (plug flow);  local concentrations: radial distribution (no backmixing, but no plug flow);  local concentrations: radial and axial distributions (backmixing). Modeling the Extraction

20. Solid phase (raffinate phase) Concentration of extractible substances in bulk solid:  accumulated depletion of the solid (mean value);  depletion of solid related to the remaining content;  remaining concentration of extractible substances: radial and axial distribution. Concentration of substances in single particles:  mass transport by diffusion;  mass transport resistance by chemical reactions and/or phase transitions;  simple geometric particles, complex shape;  monodispersity of solid particles (size), multidispersity of the solid particles (size distribution). Modeling the Extraction

21. Operating parameters  Pressure,  temperature,  density of the fluid,  quantity of solvent per unit of time and mass of solid (solvent ratio);  chemical composition of the extracting solvent. Modeling the Extraction

22. Pretreatment of the solid  size reduction and enlargement of surface;  destruction of the plant cells  adjustment of the water content;  chemical reactions for setting free the extract compounds. Modeling the Extraction

23. m = mass of extract components; m s = mass of the solid substrate; c m = mean concentration of extractible components in the solid. Transport of extract in the solid to the interface and the fluid: Steady State Approximation

24. No phase transition at the interface:  s = mass transfer coefficient in the solid phase;  F = mass transfer coefficient in the fluid phase; k = total mass transfer coefficient; c 0 = initial mean concentration of extractible components in the solid; c  = concentration of extracted components in the bulk of the fluid; A = mass transfer area. For k = const.: Mass transport resistance in the solid dominant: Steady State Approximation

25. Constant rate of extraction: The extraction can be calculated by dimensionless correlations, e.g. for a fixed bed (Wakao and Kaguei):  F = mass transfer coefficient solid-fluid; d = diameter of a volume equivalent sphere; D G = self diffusion coefficient of the fluid; = viscosity of fluid; u = linear flow velocity of fluid. Steady State Approximation

26. Radial distribution of porosity in a fixed bed

27. Tubular reactor Radial distribution of flow velocity

28. Influence of direction of flow

29. Numerical solution for breakthrough curves

30. Axial and radial concentration profiles Extraction of caffeine from coffee beans

31. Determination of effective diffusion coefficient Extraction of sugar from coffee grounds

32. Extraction of oil from soja bean flakes Determination of effective diffusion coefficient

33. Depletion in a spherical particle

34. Determination of effective diffusion coefficient

36. Constant effective diffusion coefficient, calculated from total amount of extract Extraction of theobromine from cocoa seed shells Modeling the extraction

37. Extraction of theobromine from cocoa seed shells Constant effective diffusion coefficient, incl. Mass transfer resistance to fluid Modeling the extraction

38. Extraction of theobromine from cocoa seed shells Experimental results

39. The VTII-Model for the Extraction from Solids Using Supercritical Solvents  equilibrium distribution between solid and supercritical solvent (adsorption isotherm);  diffusion in the solid (effective diffusion coefficient or effective transport coefficient as defined by the transport model);  mass transfer from the surface of the solid to the bulk of the fluid phase (supercritical solvent);  axial dispersion (effective dispersion coefficient, taking into account inhomogeneities of the fixed bed, the solvent distribution and the influence of gravity). Modeling the Extraction

40. Mass balance for the fluid phase: Mass balance for the solid phase: Equilibrium between fluid phase and solid phase: Overall mass transfer coefficient: Modeling the Extraction: VT II-Model

41. c s = mean concentration of extract components in solid phase; c F = concentration of extract in the fluid (supercritical solvent); D ax = axial dispersion coefficient; u z = void volume linear velocity of supercritical solvent; K(  c s ) = equilibrium distribution coefficient solid and fluid phase; D es = effective diffusion coefficient in the solid phase; k oG = overall mass transfer coefficient related to the fluid phase; z = coordinate in axial direction;  = void volume fraction (porosity of the fixed bed); t = time of extraction; a = specific surface of solid phase (mass transfer surface area);  s = density of solid; k 1, k 2 = coefficients of the sorption isotherm (Freundlich-isotherm);  F = mass transfer coefficient for the fluid phase. Modeling the Extraction: VTII-Model

42. Extraction of theobromine from cocoa seed shells with CO 2 Fitting of laboratory experiment to VT II-model

43. Extraction of theobromine from cocoa seed shells with CO 2 Prediction of scale-up (40) with VT II-model

44. Solubility of theobromine in CO 2

45. Solubility of theobromine. Influence of water

46. Extraction of theobromine from cocoa seed shells with CO 2 Influence of water on extraction

47. Extraction of theobromine from cocoa seed shells with CO 2 Influence of fluid flow velocity, solvent ratio

48. Extraction of theobromine from cocoa seed shells with CO 2,, Pilot plant experiments Concentration profiles

49. Extraction of theobromine from cocoa seed shells with CO 2,,, VT II - model Simulation of concentration profiles

50. Extraction of oil from rape seeds

51. Influence of solvent ratio on loading of gas phase Extraction of oil from rape seeds

52. Extraction of oil from palm fruits

54. Extraction of oil from a wild species of oil palm

55. Different supercritical solvents, different entrainers Extraction of soy bean flakes

56. Enriching by precipitation

57. Substrate: Aparisthmium cordatum Extracts obtained with different solvents

58. Multistage extraction

59. Gas extraction plant

60. Flow scheme of simple laboratory plant

61. Flow scheme of laboratory plant

62. Laboratory Plant: Penang

63. Flow scheme of a laboratory plant

64. Flow scheme of pilot plant