Optimization Of Separation Process Of Ternary Azeotrope Containing Alcohol By Extractive Distillation-Pervaporation Hybrid Process

In the process of chemical,petroleum,pharmaceutical and other industrial production,ternary azeotropic complex mixtures containing alcohols are produced.It is difficult to achieve effective separation of complex systems by traditional distillation.In this paper,vapor recompression-heat integration extractive distillation process and extractive distillation-pervaporation hybrid process are proposed for the separation of isobutanol/ethanol/water,acetonitrile/n-propanol/water and ethyl acetate/isopropanol/water systems to achieve green and efficient separation of complex ternary systems.The economic and environmental impacts of different processes are investigated.The best entrainer is determined by relative volatility,selectivity and biotoxicity index.Ethylene glycol is used to separate isobutanol/ethanol/water and ethyl acetate/isopropanol/water.Glycerol is used to separate acetonitrile/n-propanol/water.For isobutanol/ethanol/water system,the pervaporation unit based on mixed matrix membranes incorporated with polydopamine-coated metalorganic framework is used to replace the entrainer recovery column to establish the extractive distillation-pervaporation hybrid process.The flux of the membrane to water and glycerol is 0.567 kg·m^-2·h^-1and 0.00177 kg·m^-2·h^-1,respectively.The energy saving technology of heat integration is further used to improve the hybrid process.The TAC of extractive distillation-pervaporation hybrid process with heat integration is 9.8%lower than that of extractive distillation.For acetonitrile/n-propanol/water system,the coefficient of performance of the extractive distillation column for acetonitrile is 5.1,which meets the technical requirements of vapor recompression.The extractive distillation process is improved by using heat integration,single column vapor recompression and pervaporation unit based on cellophane membrane.The flux of water and glycerol by the membrane is 18.18kg·m^-2·h^-1 and 0.092 kg·m^-2·h^-1,respectively.The TAC of single column vapor recompression-heat integration extractive distillation and extractive distillation-pervaporation hybrid process are 60.19%and 74.50%lower than that of extractive distillation,respectively.For ethyl acetate/isopropanol/water system,the coefficients of performance of the extractive distillation column for ethyl acetate and isopropanol are 20.34 and 8.34 respectively,which meet the technical requirements of vapor recompression.The energy saving and consumption reduction of extractive distillation are realized by using heat integration,double column vapor recompression and pervaporation unit based on mixed matrix membranes.The TAC of two column vapor recompression-heat integration extractive distillation and extractive distillation-pervaporation hybrid process decreased by 14.63%and43.09%,respectively.Life cycle assessment is used to analyze the environment of the proposed processes.Global warming potential（GWP）and acidification potential（AP）are selected to evaluate the environmental impact.For isobutanol/ethanol/water system,the GWP and AP per thousand moles of mixture are reduced by 33.20%and 33.03%by using the improved process of pervaporation unit.For acetonitrile/n-propanol/water system,the GWP and AP per thousand moles of mixture are reduced by 53.87%and 53.98%respectively by single column vapor recompression technology and pervaporation unit.For ethyl acetate/isopropanol/water system,the GWP and AP per thousand moles of mixture are reduced by 75.45%and 75.51%by double column vapor recompression technology and pervaporation unit.