醋酸甲酯和甲醇热集成变压精馏分离工艺模拟与优化

基于对醋酸甲酯与甲醇二元共沸特性的分析，提出热集成变压精馏分离醋酸甲酯和甲醇的工艺. 利用Aspen Plus软件对该分离过程进行模拟，以NRTL活度系数方程为物性计算方法，其二元相互作用参数由气液相平衡数据回归，分析了加压塔和常压塔的理论板数、进料位置及回流比对分离效果的影响，并进行了能耗比较. 结果表明，该工艺能很好地分离醋酸甲酯和甲醇，较佳的工艺条件为：加压塔操作压力909 kPa，理论板数32，第21块板进料，回流比4.2，塔釜醋酸甲酯纯度99.8%；常压塔操作压力101 kPa，理论板数30，第20块板进料，回流比4.6，塔釜甲醇纯度99.0%. 与常规变压精馏相比，热集成变压精馏可节能达45.8%；与以水为萃取剂的萃取精馏分离工艺相比，热集成变压精馏分离工艺更适合醋酸甲酯与甲醇体系的分离.

Simulation and Optimization of Heat-integrated Pressure Swing Distillation for Separation of Methyl Acetate and Methanol

Heat-integrated pressure swing distillation for separation of methyl acetate and methanol was investigated based on the pressure-sensitivity of azeotropic composition. The separation process was simulated by Aspen Plus software using the thermodynamic model NRTL with binary parameters between two components obtained by experimental data of vapor liquid equilibrium (VLE). The influences of number of theoretical plates, feeding location and reflux ratio on the separation efficiency and energy consumption of high-pressure distillation and atmospheric distillation columns were analyzed. The results show that they are efficiently separated by heat-integrated pressure swing distillation, and the optimal conditions are as follows: for high-pressure column, the pressure is 909 kPa, number of theoretical plates 32, feeding location at the 21th plate, and reflux ratio 4.2, the purity of methyl acetate reaches 99.8% at the bottom of tower; for atmospheric pressure column, the pressure is 101 kPa, number of theoretical plates 30, feeding location at the 20th plate, and reflux ratio 4.6, the purity of methanol reaches 99.0% at the bottom of tower. The heat-integrated pressure swing distillation can save energy by 45.8% compared with conventional one, and the former is also more attractive than the extractive distillation using water as an entrainer for separation of azeotropic system.