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NCHU-SF : Ch. 2-11 SUPERCRITICAL FLUIDS FOR SEPARATION.

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Presentation on theme: "NCHU-SF : Ch. 2-11 SUPERCRITICAL FLUIDS FOR SEPARATION."— Presentation transcript:

1 NCHU-SF : Ch. 2-11 SUPERCRITICAL FLUIDS FOR SEPARATION

2 NCHU-SF : Ch. 2-12 What for do we need phase equilibrium? Design of solvent cycle (process) Objectives

3 NCHU-SF : Ch. 2-13 Solubility of the compounds Change of solubility with process conditions Capacity of the solvent Solubility of solvent in condensed phase Distribution of compounds between the phases (separation factor, selectivity) Two-phase area What do we need to know about phase equilibrium? Objectives

4 NCHU-SF : Ch. 2-14 For what type of systems (chemical compounds) do we need phase equilibrium? CO 2, C 3 H 8, H 2 O,....(gases) Paraffins, glycerides, vitamins,... Terpenes, sesquiterpenes, mono-, di-, tri-.... Objectives

5 NCHU-SF : Ch. 2-15 Extraction with Supercritical Fluids The need for phase equilibria: Solubility, K-factor, Separation factor, Two-phase region Flow scheme of gas extraction (SFE)

6 NCHU-SF : Ch. 2-16 Kennedy 1950 Solubility of quartz in water

7 NCHU-SF : Ch. 2-17 Poynting-effect Vapor pressure enhancement E.U. Franck 1956 ____ 25 o C, ------ 500 o C P 02 /P 01 VLVL

8 NCHU-SF : Ch. 2-18 Poynting-Factor System: Ethanol - Water, 343 K EthanolWater kPa 10 1.0022 1.0006 1000 1.022 1.0065 10000 1.24251.0667

9 NCHU-SF : Ch. 2-19 Density CO 2 (calc. Bender EOS)

10 NCHU-SF : Ch. 2-20 Vapour Pressure vs. Temperature

11 NCHU-SF : Ch. 2-21 Density of supoercritical Fluid responsible for solvent power (increasing with pressure, decreasing with temperature) Hydrostatic pressure enhances effective vapour pressure (Poynting effect, small) Temperature increases vapour pressure (exponentially, big effect) Influences on Solute Concentration in Gaseous Phase

12 NCHU-SF : Ch. 2-22 Solubility of Caffeine in CO 2 Gährs 1984 Ebeling, Franck 1984 Johannsen, Brunner 1994

13 NCHU-SF : Ch. 2-23 Tsekhanskaja 1964 Solubility [g/l] Solubility of Naphthalene in Ethylene

14 NCHU-SF : Ch. 2-24 Brunner 1978 Oleic acid - ethylene

15 NCHU-SF : Ch. 2-25 Solubility of oleic acid in various gases Brunner 1978

16 NCHU-SF : Ch. 2-26 Solubility of Triglycerides in sc Gases Triglycerides of palm oil Brunner 1978

17 NCHU-SF : Ch. 2-27 Solubility in sc CO 2

18 NCHU-SF : Ch. 2-28 Solubility of Xanthines in dry sc CO 2 Johannsen and Brunner 1994

19 NCHU-SF : Ch. 2-29 P,T,x-diagram of a binary system

20 NCHU-SF : Ch. 2-30 P,x-diagram ethane - heptane Kay 1938

21 NCHU-SF : Ch. 2-31 Kay 1938 T,x-diagram ethane - heptane

22 NCHU-SF : Ch. 2-32 Melting point temperature of B higher than critical temperature of A Phase equilibria of a binary system

23 NCHU-SF : Ch. 2-33 Phase equilibrium in a binary system Melting point temperature of B higher than critical temperature of A; Interrupted critical curve.

24 NCHU-SF : Ch. 2-34 P,T- projections of phase boundary lines

25 NCHU-SF : Ch. 2-35 Phase behaviour of a ternary system Temperature dependence Pressure dependence

26 NCHU-SF : Ch. 2-36 CO 2 - benzene - oleic acid

27 NCHU-SF : Ch. 2-37 Ethylene - DMF - C18 fatty acids

28 NCHU-SF : Ch. 2-38 Solubility Enhancement by a Modifier

29 NCHU-SF : Ch. 2-39 Schmitt 1984 Solubility Enhancement by Entrainer (Modifier)

30 NCHU-SF : Ch. 2-40 Gährs 1984 Solubility of Caffeine in CO 2 Influence of nitrogen

31 NCHU-SF : Ch. 2-41 Influence of propane Prausnitz, Joshi 1984 Solubility of Phenanthrene in CO 2

32 NCHU-SF : Ch. 2-42 Phase Equilibrium in a Ternary System Brunner 1983

33 NCHU-SF : Ch. 2-43 Brunner 1983 Solubility in a gas with a modifier Influence of temperature

34 NCHU-SF : Ch. 2-44 Brunner 1983 Separation Factor Influence of entrainer

35 NCHU-SF : Ch. 2-45 Influence of concentration Brunner 1983 Separation Factor

36 NCHU-SF : Ch. 2-46 Three Phase Equilibrium

37 NCHU-SF : Ch. 2-47 P,T-diagrams of Complex Mixtures

38 NCHU-SF : Ch. 2-48 Measuring Phase Equilibrium

39 NCHU-SF : Ch. 2-49 Measuring Phase Equilibrium

40 NCHU-SF : Ch. 2-50 Modeling of Phase Equilibrium with EOS HPW modification of RK-EOS

41 NCHU-SF : Ch. 2-51 Gas-Liquid Phase Equilibrium Two different ways: A = standard fugacity  i = activity coefficient: g E -models) B = fugacity coefficient: Equations of state Thermodynamic Equilibrium

42 NCHU-SF : Ch. 2-52 VLE-Calculation: With the simplification: since :  Calculation of Phase Equilibrium

43 NCHU-SF : Ch. 2-53 Low pressure High pressure Phase Equilibrium: Non Ideal Solutions

44 NCHU-SF : Ch. 2-54 P = 101 kPa Methanol - water Chloroform - acetone    = 1 Concentration dependence of separation factor

45 NCHU-SF : Ch. 2-55 Concentration dependence of separation factor

46 NCHU-SF : Ch. 2-56 T = const. VLE T = const. VLE x sf = const. x sf = solvent free concentrations in liquid phase Limiting values of the partition coefficient K Phase Equilibrium

47 NCHU-SF : Ch. 2-57 Limiting values of separation factor  Binary system i-j in a multicomponent systemAt low pressure Binär: Phase Equilibrium

48 NCHU-SF : Ch. 2-58 Murphy´s Law of Thermodynamics THINGS GET WORSE UNDER PRESSURE


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