Separation of DMC-MeOH azeotrope by PV-heat pump distillation process
The separation of dimethyl carbonate(DMC)-methanol(MeOH)azeotropes has the characteristics of high energy consumption and low energy efficiency.As a liquid-liquid separation technology,pervaporation is not limited by vapor-liquid equilibrium and is widely used in the separation of azeotropic systems.Conventional pervaporation processes require an external energy supply to maintain a constant residual liquid temperature.Besides,the permeation side requires external cooling to condense collection,reducing energy efficiency.In this study,a coupled membrane-heat pump distillation process was designed and developed,in which the DMC-MeOH azeotrope system was separated by polydimethylsiloxane(PDMS)/polyvinylidene fluoride(PVDF)composite membrane,the energy integration optimization was performed with a heat pump,and the simulation results were compared with the extracted distillation,pressure swing rectification and conventional membrane-rectification processes reported in the literatures.The results show that the PV-heat pump distillation process has a good energy-saving effect when the atmospheric pressure,azeotrope feed and the stage cut of PV unit is 0.3.Compared with the pressure swing distillation with heat integration,the energy consumption can be reduced by about 47％and the energy efficiency can be increased by 90％.The membrane-heat pump distillation process designed in this study provides a new development direction for the separation of azeotropes.
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