Extractive distillation is a kind of particular distillation method that can break azeotropes to recover the product by adding suitable entrainer which can enhance relative volatility of azeotropes during the separation process.It is widely used for the great economic and environment performance.Meanwhile,the process can be much energy-intensive due to the use of large amount of entrainer that needed to be further reduced energy consumption with some energy conservation technology.In this paper,the separation and process intensification of a ternary mixture system which contains two azeotropes will be focused.In this paper,extractive distillation technology is selected to separate the ternary mixture containing water.There are two kinds of extractive distillation processes proposed for the separation,including the indirect extractive distillation process and direct extractive distillation process.The binary parameters of the components are determined through UNIQUAC model.A suitable entrainer is selected after comprehensive consideration of COSMO-SAC screening,relative volatility and the analysis of residue curve maps.On this basis,the sequential modular procedure is applied to optimize the basic process after determining a proper operation pressure and entrainer flowrate.Heat integration and vapor recompressed heat pump technology have been applied for reducing energy consumption and cost.The temperature-entralpy diagram is used to show the utility requirement and heat recovery.The results show that both indirect extractive distillation and direct extractive distillation show great performance on the separation of acetonitrile/1,4-dioxane/water system that the product purity can be up to99.9 mol%.Direct extractive distillation is turned out to be more promising on the energy-conservation and economic aspect than indirect extractive distillation.The most energy-saving and environmental friendly process is single heat pump assisted direct extractive distillation that achieves an energy reduction by 53.58% compared to the indirect scheme,while the direct scheme assisted with heat integration performs best that achieves a reduction by 40.38% on total annual cost.It is similarly in the isopropanol/tetrahydrofuran/water system that both indirect extractive distillation and direct extractive distillation show great performance on the separation process and direct extractive distillation performs better in energetic and economic.The double-heat pump assisted direct extractive distillation with heat integration shows the best performance in energy conservation and reducing cost,which achieve a reduction on energy consumption and total cost by 64.97% and 34.23%respectively compared to the direct extractive distillation process.According to the results of the research,extractive distillation is very effective for the separation and purification of organic wastewater containing azeotropes since it can efficiently separate and recover specific organics from wastewater.When double heat pump are applied,the total annual cost is lower than the heat integration assisted scheme since the operating cost has been rapidly reduced. |