结合图论和基团贡献法的非均相共沸精馏挟带剂设计

Computer aided design for entrainer in heteroazeotropic distillation by combining group contribution method with graph principle

非均相共沸精馏挟带剂的计算机辅助分子设计(CAMD)由分子合成、分子筛选及分子确认3个环节递进构成。在分子合成环节,预选基团,限定合成分子的基团总数及类型,基于图论原理实现由基团到分子的自动合成。在分子筛选环节,依据基础物性筛选指标形成基础分子库,输入待分离物系,采用非均相共沸物形成判据筛选出若干候选分子。在分子确认环节,由非均相共沸温度及组成、挟带剂的汽化热等参数组成模糊综合评判函数,实现分子排序,从而输出一组较优挟带剂。以乙酸-水物系、乙腈-乙酸乙酯物系为例,得到了相应设计结果,与文献结果进行了对比。研究表明该方法及所编程序具备可靠实用性,可为近沸程及共沸混合物分离过程的开发与设计提供先导性支持。

Heterogeneous azeotropic distillation is an effective technology to separate close boiling point or homogeneous azeotropic mixture.The first step is to select appropriate entrainers.A computer aided molecular design（CAMD）methodology for the entrainer in heterogeneous azeotropic distillation is presented in this study.The CAMD methodology is comprised of three step-by-step stages,which are molecular synthesis,molecular screening and molecular recognition.In the stages of molecular synthesis,groups are pre-selected,the total number and types of the groups for the synthesized molecule are limited,and the automatic combination of groups is completed by using a graph algorithm.In the stages of molecular screening,the basic molecular library is formed by using several limited rules of basic physical properties,such as molecular weight and boiling point.The molecules in the basic molecular library are screened when they form the heterogeneous azeotropic with input components to be separated.As a result,a series of entrainer candidates are listed.In the stages of molecular recognition,the fuzzy comprehensive assessment function,which is composed of several important factors,such as temperature and composition of heterogeneous azeotropic point,and heat of vaporization of entrainer,is used to rank entrainer candidates.Consequently,a group of appropriate entrainers are obtained.For acetic acid-water system and acetonitrile-ethyl acetate system,several better entrainers are obtained.It indicates that the CAMD methodology and the computer procedure is practical and reliable,and the resulting entrainers is the basis for research or conceptual design of heterogeneous azeotropic distillation processes.