乙酸乙酯-水共沸体系萃取精馏萃取剂的分子设计

Extractants design based on modified genetic algorithm for ethyl acetate-water system

本文以修改的遗传算法设计萃取精馏乙酸乙酯-水共沸体系萃取剂的分子,设计过程包括4个部分:初始化种群,适应度函数计算,遗传算法操作算子的设计,分子设计结果分析。用基团号重新编码的方案表示初始化种群中的分子,适应度函数以给定的分子性质限制来表示,以S形函数和高斯函数度量,改进遗传算子中的选择策略和交叉算子,使分子结构稳定且形式多样,避免遗传算法不易得到全局最优解和收敛容易提前。分子设计结果分析是从工业应用的角度出发,对设计出的最终子代中适应度值接近于0.70的分子,从相对挥发度、熔点、沸点等方面进行综合筛选,得到经济合理、应用价值较高的萃取剂。最终编制出乙酸乙酯-水体系萃取精馏萃取剂分子的程序,找出乙二醇,二乙醇胺及二甲亚砜等较好的萃取剂。作者等提出的方法对预测相对挥发度的值与顾正桂等报道值的相对偏差小于10%,方法可靠。

A novel strategy for designing extractants modified genetic algorithm for ethyl acetate-water system is presented.The entire process may be summarized as follows：Giving the characteristic and goals of a extractive distillation process.Selecting the groups that should be considered for the problem.Determining and evaluating the extractant structure by solving the combinatorial problems and using the feasibility criteria.Using the proximate analysis method to make the final selection of one or more molecules to satisfy the particular needs of the given process.A new code scheme is established to simplify the synthetical molecular form.In this work,two kinds of fitness functions as sigmoidal fitness function and gaussian function are used depending on the nature of property constraints.For the sake of avoiding the disadvantages of genetic algorithm with converging early and losing easily globally optimal results,cross generation elitist selection and misplaced crossover are improved.The methodology and design process for the molecular design are given.The computer program for the ethyl acetate-water system is developed.And the prediction precision of relative volatility is less than 10%according to the document reported.