特殊精馏分离甲乙酮-水共沸物系的工艺模拟与优化

由于共沸物的存在，甲乙酮-水混合物的分离在工业生产上一直是一个具有挑战性的问题。采用萃取精馏和变压精馏对分离工艺进行流程模拟与优化，得到摩尔分数为99.9%的甲乙酮产品，以年度总费用(TAC)最小为目标函数，采用序贯迭代法对其进行优化，得到最小TAC为6.569×10⁵美元。通过分析比较3种常用萃取剂无限稀释相对挥发度的大小，筛选出乙二醇作为萃取剂，得到最佳萃取剂用量、理论板数及进料位置；针对常规变压精馏工艺提出热集成方案，与采用方案前相比，年度总费用降低了27.1%。最后，对萃取精馏、变压精馏和热集成变压精馏3种分离工艺年度总费用进行对比，萃取精馏工艺比热集成变压精馏工艺年度总费用降低了21.5%。结果表明，在经济性方面，萃取精馏相比于热集成变压精馏更适合甲乙酮-水共沸物系的分离。

Simulation and optimization of special distillation for the separation of the methyl ethyl ketone-water azeotrope system

Due to the existence of an azeotrope, the separation of methyl ethyl ketone-water mixtures has always been a challenging problem in industrial production. In this paper, extractive distillation and pressure swing distillation are used to simulate and optimize the separation process. The target mole fraction is 99.9% of the methyl ethyl ketone product, with the minimum total annual cost (TAC) as the objective function. Optimization was carried out by the sequential iteration method, and the minimum calculated TAC was 6.569×10⁵ US dollars. By analyzing and comparing the relative volatility of three common extractants at infinite dilution, ethylene glycol was chosen as the extractant, and the optimal amount of extractant, the number of theoretical plates and the feeding position were obtained. The proposed thermal integration scheme for the conventional pressure swing distillation process reduced the total annual cost by 27.1%. Finally, by comparing the total annual cost of the three separation processes of extractive distillation, pressure swing distillation and thermal integrated pressure swing distillation, the total annual cost of the extractive distillation process is reduced by 21.5% compared with the thermal integrated pressure swing distillation process. The results show that, in terms of economy, extractive distillation is more suitable for separation of the methyl ethyl ketone-water azeotrope than heat-integrated pressure swing distillation.