热集成变压精馏分离乙酸乙酯与乙醇工艺及模拟

基于乙酸乙酯与乙醇共沸特性的分析,提出了热集成变压精馏的分离工艺,由加压塔和常压塔串联构成。选择NRTL (non random two liquids)模型为物性计算方法,其二元相互参数由汽液相平衡数据回归,利用Aspen Plus软件对提出的分离工艺进行模拟与优化,详细分析了两塔的理论板数、进料位置及回流比对分离的影响,并对比能耗。结果表明,热集成变压精馏分离工艺能很好地实现乙酸乙酯与乙醇的分离,得到最佳的工艺条件,与常规变压精馏相比,热集成变压精馏可节约加热蒸汽34.7％,为共沸物分离的设计和过程节能提供依据。

Simulation for separation of ethyl acetate and ethanol by heat-integrated pressure swing distillation

Heat-integrated pressure swing distillation for separation of ethyl acetate and ethanol was investigated based on the pressure-sensitivity of the azeotropic composition, and the separation sequence was formed by two columns operating at different pressures. The simulation of separation process was carried out satisfactorily by means of a package of commercial software Aspen Plus and using the thermodynamic model NRTL (non random two liquids) with binary parameters between ethyl acetate and ethanol obtained by experimental data of vapor liquid equilibrium (VLE). The factors affecting the separation efficiency and energy consumption including the number of theoretical plates, feed location and reflux ratio of two columns were analyzed. The results showed that ethyl acetate and ethanol could be efficiently separated by heat-integrated pressure swing distillation, and the optimal conditions were obtained. The heat-integrated pressure swing distillation could save heating steam by 34.7％ compared with conventional pressure swing distillation, which could provide an effective method for the design and energy-saving of azeotropic system separation.