原甲酸三甲酯-醋酸萃取精馏全局多目标优化

Global multi-objective optimization of trimethyl orthoformate-acetic acid extractive distillation

在生产杀菌剂嘧菌酯中间体过程中,反应物原甲酸三甲酯(TMOF)与生成物醋酸(HAc)发生共沸,导致反应物堆积和原料损耗。为解决共沸物分离问题,使用Hayden-O􀆳Connell修正的UNIFAC基团贡献法研究其汽液平衡,设计常规萃取精馏(CED)、侧线萃取精馏(SED)、隔壁塔萃取精馏(EDWC)三种工艺,以分离组分摩尔纯度、再沸器热负荷(Q)、年度总费用(TAC)为目标,运用灵敏度耦合箱线图响应面法(S-BBD)对三种工艺参数分别优化。结果表明,优化方法预测值与实际值存在较优拟合关系,CED、SED、EDWC对TAC和Q的预测误差均不超过1%。分离纯度相同时,SED较CED节约10.37%TAC和6.88%热负荷,EDWC较CED节约10.65%TAC和10.53%热负荷,三种工艺方案均可为化工实际生产提供理论基础。

The highest azeotrope exists between the reactant trimethyl orthoformate(TMOF)and the product acetic acid(HAc)in the production of 3-(methoxy methotenyl)-2(3H)benzofuranone,which leads to the accumulation of reactants and the loss of raw materials and is not conducive to the forward reaction.For TMOF-HAc system,vapor-liquid equilibrium was calculated and analyzed by Hayden-O􀆳Connell􀆳s UNIFAC group contribution method with modified fugability coefficient.After error verification,NRTL-HOC model was used as the basis of simulation distillation.The azeotrope can be separated by empirical extractive distillation.The entrainment performance of HAc with N-methyl acetamide(NMA)and N-methyl pyrrolidone(NMP)was compared,and NMP was selected as the extractant.Conventional extractive distillation(CED),side-stream(liquid)extractive distillation(SED)and extractive dividing-wall column(EDWC)were designed with the objective of molar purity of system recovered components,reboiler thermal load(Q)and annual total cost(TAC).Sensitivity analysis was used to adjust the parameters of the three processes in advance.Based on the multi-objective constraints,the optimal parameter range was divided as the initial data of Box-Behnken response surface method(BBD-RSM)optimization,and then the global optimization of the three processes was further conducted by BBD within the specified range.The most economical scheme was formulated by optimizing the data regression multi-objective equation,and the mole purity was 99.8%HAc and 99.9%TMOF.The results show that EDWC and SED can save more economic input and reboiler heat load than CED under the same separation purity condition.SED can save 10.37%TAC and 6.88%heat load,and EDWC can save 10.65%TAC and 10.53%heat load.The results show that there is a good fitting relationship between the predicted value and the actual value,and the prediction errors of TAC and Q by CED,SED and EDWC are all less than 1%.All three process schemes can provide theoretical basis for actual chemical production.