基于离子液体的乙腈-乙醇-水共沸体系节能分离

Energy-Saving Separation of Acetonitrile-Ethanol-Water Azeotropic System Based on Ionic Liquid

乙腈生产过程中产生的乙腈-乙醇-水物系,由于在常压下产生了3种二元共沸物和1种三元共沸物,采取常规精馏无法对物系进行有效分离,因此基于COSMO-SAC理论对具有应用潜力的4种离子液体进行筛选,选定1,3-二甲基咪唑磷酸二甲酯([DMIM][DMP])作为分离乙腈-乙醇-水物系的适宜萃取剂,并利用σ-谱图对离子液体与该物系的作用机理进行分析;采用Aspen Plus软件建立了基于离子液体分离乙腈-乙醇-水物系的萃取精馏流程。以年度总费用(TAC)最低为优化目标,并将CO_(2)排放成本计入目标函数中进行流程优化。在此基础上,为了更有效节能,进一步设计优化了热泵精馏萃取分离流程。最终热泵精馏流程TAC比常规流程降低16.82%,CO_(2)排放费用减少了23.35%。

The acetonitrile-ethanol-water system generated during the production of acetonitrile,due to the generation of three binary azeotropes and one ternary azeotrope under normal pressure,cannot be effectively separated by conventional distillation.Based on the COSMO-SAC theory,four ionic liquids with application potential were screened,1,3-dimethylimidazole dimethyl phosphate([DMIM][DMP])was selected as a suitable extractant for the separation of this system,and theσ-spectrum was used to analyze the mechanism of interaction between the ionic liquid and the system.Moreover,the Aspen Plus software was used to establish an extractive distillation process based on the ionic liquid separation of the acetonitrile-ethanol-water system.The minimum total annual cost(TAC)was taken as the optimization goal,and the carbon dioxide emission cost was included into the objective function for process optimization.On this basis,for more energy conservation,the heat pump distillation and extraction separation process was further designed and optimized.Finally,TAC of the heat pump distillation process is 16.82%lower than that of the conventional process,and the cost of carbon dioxide emissions is reduced by 23.35%.