变压精馏分离乙醇-氯仿共沸物的动态特性

基于乙醇-氯仿二元共沸体系的压力敏感特性,利用Aspen Plus软件,以年度总费用(TAC)最小为目标函数,模拟和优化了变压精馏稳态工艺,所得乙醇和氯仿产品纯度均大于99.9%(质量分数).利用稳态模拟考察了不同热集成变压精馏工艺的经济性.利用Aspen Dynamics软件考察了不同热集成变压精馏工艺的动态特性,建立了不同热集成变压精馏工艺的稳健控制方案.结果表明:完全热集成工艺与无热集成和部分热集成工艺相比,经济性最优;组成-温度串级控制结构可较好地控制无热集成和部分热集成流程,压力-补偿温度控制结构在完全热集成工艺中可实现稳健的控制;虽然完全热集成工艺经济性最优,但部分热集成工艺的可控性优于完全热集成工艺.本文研究对工业分离含低碳醇的二元共沸物热集成变压精馏工艺有一定的参考价值.

Dynamic characteristics of pressure-swing distillation for ethanol-chloroform separation

The steady-state simulation of the pressure-swing distillation(PSD) for separating an azeotrope of ethanol-chloroform was studied based on the pressure-sensitive of the mixture. The process was optimized by minimizing the total annual cost(TAC) using Aspen Plus. The obtained purity of the products was more than 99.9%. The economy of different heat-integrated processes was investigated on the basis of steady-state simulation. The dynamic characteristics of different heat-integrated PSD for separating ethanol-chloroform binary azeotropic system were studied by Aspen Dynamics. Robust control strategies were built based on the characteristic of different heat-integrated PSD process. The results showed that the economy of the fully heat-integrated process was better than no and partially heat-integrated process and composition-temperature cascade control structure was suitable for no and partially heat-integrated PSD while pressure-compensated temperature control structure was useful for fully heat-integrated PSD. Although fully heat-integrated PSD has the optimal economic efficiency, partially heat-integrated PSD can achieve more robust control than fully heat-integrated PSD. The studies provide certain reference value for the separation of the lower alcohol binary azeotrope with heat-integrated PSD in industrial application.