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超臨界流體分離技術 Special Topics on Separation Using Supercritical Fluids 化學工程學系 與 環境工程學系 碩博士班 選修課程

超臨界流體分離技術 Special Topics on Separation Using Supercritical Fluids 化學工程學系 與 環境工程學系 碩博士班 選修課程 國立中興大學 化材館. Content of Lectures. Topics I. Overview on Separation Processes with scFluids Solubility in Supercritical Fluids/ Phase Equilibria Extraction from Solid Substrates (I, II)

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超臨界流體分離技術 Special Topics on Separation Using Supercritical Fluids 化學工程學系 與 環境工程學系 碩博士班 選修課程

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  1. 超臨界流體分離技術 Special Topics on Separation Using Supercritical Fluids 化學工程學系 與 環境工程學系 碩博士班 選修課程 國立中興大學 化材館

  2. Content of Lectures

  3. Topics I Overview on Separation Processes with scFluids Solubility in Supercritical Fluids/ Phase Equilibria Extraction from Solid Substrates (I, II) Countercurrent Multistage Extraction (I, II)

  4. Topics II Solvent Cycle, Heat/ Mass Transfer, Precipitation Supercritical Fluid Chromatography, SFC Membrane Separation EnzymaticReactions in scFluids for Separation Crystallization in Supercritical Fluids General Aspects of Separation Processes Videos Visited to Supercritical Fluid Plants

  5. Clean Air Separation Contaminants Effluent Air Recycle Side Products Separation Purification Separation Reaction Recovery Products Effluent Water Separation Contaminants Clean Water Generalized Process Scheme Raw Materials

  6. Separation Technology in the Past • Focus on Chemistry and Reactor Technology • Separation Technology was Added Afterwards • for • Recovery and Purification of Products from Reaction Mixtures • Minimisation of Waste Discharged into the Environment • Chemical Engineering Education Focussed on Large Scale Petrochemical Separations

  7. Separation Technology in the Past • Consequences: • Chemistry and Reactor Technology Capabilities Limits • Maximum Yields • Minimal Time for Separation Technology Development • Most New Processes use Existing Separation Technology • Drive for Product Purity and Environmental Impact Minimi-zation Results in Increased Production

  8. Conventional Process Distillation Best Known Most Used Strengths: Limited Equipment Simple Staging Economy of Scale Energy Costs Reliable Design and Scale Up

  9. Limits to Distillation • Low Relative Volatilities • Azeotropes • Close Boiling Points • Isomers • Feed Composition • Low Concentrations with High Boiling Point • Overlapping Boiling Points • Non-Volatile Components • Extreme Conditions (Pressure, Temperature) • Small Capacities • Product Degradation • Fouling • Uneconomical for Environmental Applications

  10. Drivers for New Separation Concepts • Sustainable Processes • Higher Molecular Efficiencies • New Feedstock Chemistry • Reduction Energy Consumption • Environmentally Benign Mass Separatiing Agents • Minimal Consumption Separating Agents • Cleaner and Purer Products • Contamination with Mass Separating Agents • Removal of Undesired Components • Purer Feedstocks • Minimisation Environmental Impact • Further Emission Reduction • Minimal Waste Stream Production

  11. Some Challenges • Clean Processes • Environmentally Benign Solvents • Solid Solvents • No Solvents • Reduced Energy Consumption • Increases Solvent / Adsorbent Capacities • Selectivity Enhancement • Reduction Evaporative Operations • Process Intensification • In Situ Separations • Hybrid Separations

  12. Benign Solvents • Replacement of Chlorinated, Aromatic and Other Harmful • Solvents in Reactions and Separations by: • Water • Aqueous Solvents • Two Aqueous Phases • Carbon Dioxide (Supercritical or Liquid) • Food Applications • Neutraceuticals, Pharmaceuticals ? • Mixtures of Unsuspected Solvents (Reactive Solvents) • Insoluble Alkane / Complexing Agent Mixtures • Solid Solvents (Adsorbents) • No Solvents • However:Low Volatile Solvents in Reactions may Create • Problems in Separation and Purification

  13. Separation Processes Distillation General Special Use Absorption Crystallization Solvent Extraction Extractive & Azeotropic Distillation Ion Exchange Adsorption: liquid feed Adsorption: gas feed Membranes: gas feed Supercritical Extraction Membranes: liquid feed Chromatography Field-induced Separations Liquid Membranes Knowledge Affinity Separationes

  14. Summary & Conclusions • Strong Drive to For New Separation Concepts • Chemical instead of Physical Separation • Solvent Free Separations • Rate Based Separations • Environmental and Product Acceptable Mass Separating • Agents • Hybrid Separation Systems • Integration of Reaction and Separation • This Requires the Application of New Often Highly • Selective Separation Systems • Application of New Separation Systems often Prohibited • by Lack of Knowledge on Design and Scale-Up

  15. Definition “Supercritical” Supercritical Fluid Supercritical Fluid Extraction - SFE (Gas Extraction)

  16. State of Solvent High pressure liquid extraction Supercritical Fluid Extraction - SFE (Gas Extraction) Absorption Adsorption L-L extraction Stripping

  17. Generalized Process Scheme

  18. Solvents EC directive 84/344/EEC Extraction solvents which are acceptable for all uses when used in compliance with GMP provided any residues or derivatives present in the product in technically unavoidable quantities present no danger to human health. Propane Ethanol Butane Carbon Dioxide Butylacetate Acetone Ethylacetate Nitrous Oxide Nitrogen, Water Mixtures

  19. Comparison of States Gas Supercritical Liquid Fluid ______________________________________________ 0.1 MPa Pc,Tc 4Pc,Tc0.1 MPa 298 K 288 K ______________________________________________  kg/m3 1 200 - 500 400 - 900 1000  kg/(ms) 10- 5 1.3.10-5 3.9.10-5 10- 3 D m2/s 10- 50.7.10-7 0.2.10-710-9 _____________________________________________________________________

  20. Density of Carbon Dioxide ---typical operating conditions Calculated with Bender-EOS

  21. „Supercritical Fluids“, Why? • New, better products • Clean products • New, better processes

  22. Advantages of Supercritical Fluids • Lower operating temperatures • improved yield • improved product properties • favourable combination of process steps • easier regeneration of the sc solvent • no liquid solvent • lower production cost

  23. Advantages of Supercritical Fluids ctd. • Solvent power comparable to liquid solvents • Solvent power adjustable by pressure and temperature changes • Very hígh volatility compared to the dissolved substances • complete separation of solvent from extract and raffinate • second phase achievable in all cases • high diffusivity, low viscosity • CO2: nontoxic, nonflammable, inexpensive, available

  24. Disadvantages of Supercritical Fluids • Elevated pressures required • Relative high costs of investment (not in general !) • Unusual operating conditions (for some industries) • Complicated phase behaviour (but only some knowledge needed for application)

  25. Example: Decaffeination Theobromine Caffeine

  26. Decaffeination of green coffee beans Lack and Seidlitz 1993

  27. Decaffeination of green coffee beans Lack and Seidlitz 1993

  28. Flow scheme of decaffeination plant Schoeller-Bleckmann design Lack and Seidlitz 1993

  29. Application of Supercritical Fluids • Dissolution: • Separation Processes • Reactions • Combinations • (e.g. Separation by Reaction) • Engineering of Properties (liquid) • Dilution • Lowering of viscosity • Lowering of concentration

  30. Application of Supercritical Fluids • Product Engineering (Materials) • Small particles • Particles with large surface area • Adsorbates • Coated particles • Engineering of Properties (solid) • Penetration • Swelling • Removal of monomers • Impregnation of substances • (Dyes, pharmaceuticals)

  31. Application of Supercritical Fluids Engineering of phase transitions Formation of solid phases (Micronization, thin layers) Variation of solubility (g-l) Variation of melting point (l-s)

  32. Application of Supercritical Fluids Product Applications I Extraction, purification, and separation of: Edible oils and fats Hops extract Natural dyes: Annatto, Hibiscus Vitamins (Tocopherols, Vit. E, Tocotrienols) Carotenoids Sterols Essential fatty acids (EPA, DHA, DPA) ...... ........

  33. Application of Supercritical Fluids Product Applications II Bioactive compounds, e.g. Pyrethrum Caffeine, Theobromine Cholesterol Spices: Capsaicin, Pepper, Coriander Mono- and Diglycerides Aroma compounds Thiosulfinates Citrus oils Antioxidants: Vitamin E, Ascorbic acid, Polyphenoles, Diacin, Genicin (Steroids) ......

  34. Application of Supercritical Fluids Separation Processes: Extraction from solids Countercurrent multistage separation Chromatographic separations Precipitation Crystallization Absorption Adsorption/Desorption and with the application of: Chemical reactions Solid and liquid surfaces ....

  35. Application of Supercritical Fluids Chemical Reactions New Syntheses Variation of reaction equilibrium Variation of reaction rate Replacing liquid solvents Examples: Hydrolysis: From starch to sugars Enzymes as catalyst in CO2-atmosphere

  36. Application of Supercritical Fluids Environmental Engineering Replacement and Recycling of Solvents Recovery of Hazardous Waste Compounds Destruction of Hazardous Waste Compounds

  37. Application of Supercritical Fluids Biotechnology Enzymatic Catalysis Engineered degradation of Biopolymers (Starch) Production of Proteins Separation of Products from aqueous solutions Sterilization/Deactivation Enantiomeric selective reactions

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