变压精馏分离乙腈-正丙醇过程模拟与优化

SIMULATION AND OPTIMIZATION OF PRESSURE SWING DISTILLATION FOR SEPARATION OF ACETONITRILE AND n-PROPANOL

基于乙腈和正丙醇二元共沸特性的分析,提出变压精馏分离乙腈和正丙醇共沸物的工艺。利用Aspen Plus软件,以Wilson模型为物性计算方法对分离过程进行模拟,以再沸器总热负荷最低为优化目标,分析高压塔和常压塔理论板数、回流比和进料位置对再沸器总热负荷的影响。结果表明,变压精馏能够实现乙腈和正丙醇的有效分离,两者质量分数均为99.90%。利用高压塔塔顶气相潜热作常压塔塔釜再沸器热源进行热量集成,热集成变压精馏相比于传统变压精馏再沸器热负荷节能28.43%,冷凝器热负荷节能31.95%。与以N-甲基吡咯烷酮为萃取剂的萃取精馏工艺相比,热集成变压精馏工艺更适合乙腈和正丙醇共沸物的分离。

Pressure swing distillation was proposed for the separation of acetonitrile and n-propanol azeotrope based on the analysis of its azeotropic characteristics.The separation process was simulated by Aspen Plus software using Wilson model as the physical property calculation method.Taking the lowest total heat load of reboiler as the optimization objective,the influence of theoretical plate number,reflux ratio and feed location on the total heat load of reboiler of high pressure distillation and atmospheric distillation columns is analyzed.The results show that the effective separation of acetonitrile and n-propanol can be achieved by pressure swing distillation with a mass fraction of 99.90%.Heat integration was used between the condenser in high pressure distillation column and the reboiler in atmospheric distillation column.The heat-integrated pressure swing distillation can save energy by 28.43% of reboiler and 31.95% of condenser compared with conventional one.Compared with the extractive distillation process with NMP as the extractant,the heat-integrated pressure swing distillation process is more suitable for the separation of acetonitrile and n-propanol azeotrope.