煤基甲醇芳构化分离过程多目标优化

Multi-objective optimization of separation unit for coal-based methanol aromatization

国内煤化工产品普遍存在产能过剩和同质化严重的问题,开发以煤基甲醇合成二甲苯的新技术具有重大意义。针对煤基甲醇合成二甲苯技术中面临分离过程能耗高的难题,本工作基于甲醇芳构化技术,利用Aspen Plus与Matlab的交互链接,对非芳烃、苯、甲苯、二甲苯、三甲苯的分离过程开展了多目标优化研究。采用NSGA-Ⅱ遗传算法,以苯-甲苯收率、二甲苯收率、年度总成本和能耗指标作为四个目标函数,分别针对传统双塔精馏序列工艺和分隔壁塔精馏工艺进行了多目标优化,发现回流比对年度总成本的影响最明显。在满足约束条件的前提下,基于最低的年度总成本对两个分离工艺进行了比较。结果表明,分隔壁塔工艺较双塔精馏序列工艺的最低年度总成本低7.7%,换热器花费低16.1%,能耗指标低26.3%。分隔壁塔工艺成本低、能耗低,具有环保、绿色、可持续性的优势。

The development of new technologies for synthesizing xylene from methanol has great significance in China,as the coal-based chemical products have been redundant and homogeneous seriously.Due to the challenge of high energy consumption in the chemical separation process,a multi-objective optimization research was carried out in the separation of non-aromatic hydrocarbons,benzene,toluene and xylene mixture using Aspen Plus and Matlab software in this work.The traditional twocolumn sequence separation process and the dividing wall column process had been simulated and optimized by NSGA-Ⅱalgorithm respectively.Total annual cost(TAC),energy consumption per product flow rate(GEC),the productivity of benzene-toluene and the productivity of xylene were set as objective functions.The results showed that effect of the reflux ratio on TAC was critical.The two separation processes were compared based on the lowest TAC under the premise of satisfying the constraints.The results indicated that the lowest TAC,heat transfer cost and GEC of the dividing wall column process were reduced about 7.7%,16.1%and 26.3%in comparison with the twocolumn sequence process,respectively.It implied that the dividing wall column process would be the best sustainable process in xylene production with lower TAC and GEC.