两两共沸型均相三元物系萃取精馏中的定量构效模型与控制策略

The energy-saving and efficient separation of azeotropic mixtures is of important scientific and practical significance in the process industry. Extraction distillation has been widely used in the binary azeotrope separation. The research and application of the separation for ternary or multiple azeotropes are more urgent and challenging because of the complexity of the distillation boundary and the unclear interaction mechanism. The objectives of the project focus on ternary homogeneous systems with three binary azeotropes. Based on the results of vapor-liquid phase equilibrium experiments, the quantitative structure-activity relationship model between relative volatility and micro-mesoscopic molecular structure information will be established based on molecular simulation software platform, the curvature feature of residue curves will be characterized, and its correlation with steady-state process parameters of extractive distillation will be investigated. Multi-objective optimization of extractive distillation process will be performed using process simulation software from two aspects of economy and dynamic characteristics, and the rule of dynamic control structure design will be explained. The strategies and rules can be used to realize the process of extractive distillation for separating the homogeneous ternary systems with three binary azeotropes. The project focuses on revealing the essential factors which impact the relative volatility of extractive distillation system by basic experiments, theoretical calculations and simulation studies. Also, the rules existed among the micro-mesoscopic molecular structure, macroscopic relative volatility and the parameters of extractive distillation can be discovered. It is significant for exploring the synthesis of extractive distillation process with ternary azeotrope system.

共沸物系的节能高效分离在过程工业中具有重要的科学意义与实用价值，萃取精馏已在二元共沸物分离上获得广泛应用。因精馏边界复杂、交互作用机理不明等原因，三元或多元共沸物分离的研究与应用较为迫切且颇具挑战性。项目选取两两共沸型均相三元共沸物，基于汽液相平衡实验结果利用分子模拟软件平台建立相对挥发度与微介观分子结构信息之间的定量构效关系模型，表征剩余曲线曲率特性并考察其与萃取精馏稳态工艺参数之间的相关联系，利用过程模拟软件从经济性与动态特性两方面对萃取精馏工艺流程进行多目标优化，阐明动态控制结构设计的规律,为实现两两共沸型均相三元混合物的萃取精馏过程提供策略与依据。项目注重利用基础实验、理论计算和模拟研究去揭示影响萃取精馏体系相对挥发度的本质因素，深入认识存在于萃取精馏中的微介观分子结构与宏观挥发性质及工艺参数的规律，对开拓三元共沸物系萃取精馏分离过程综合具有重要意义。

共沸物系的节能高效分离在过程工业中具有重要的科学意义与实用价值，萃取精馏已在二元共沸物分离上获得广泛应用。因精馏边界复杂、交互作用机理不明等原因，多元共沸物分离的研究与应用较为迫切且颇具挑战性。本项目测定了30多组含低碳醇类、烷酯类等共沸物的400多组数据点，基于NRTL、UNIQUAC、Wilson模型关联得到了80多组二元交互作用参数；将分子动力学模拟、量子化学应用于萃取剂筛选与机理分析，从分子水平探究了萃取剂与共沸物分子的相互作用，萃取剂与共沸物之间的氢键强弱与萃取效果具有一致性，氢键的产生主要由萃取剂中氧原子上的一对孤电子控制，并通过模拟结果与实验数据相结合对比验证溶剂筛选的准确性，为萃取剂的筛选提供了理论依据；基于多目标优化得到同时兼顾经济与环境的最优操作参数工艺，通过热集成、热耦合等节能技术对萃取精馏进行强化，年度总成本可降低9.3-51%；分析回流比、温度等变量确定工艺的控制点，进而开发出工艺的最优控制策略，兼顾经济性与动态特性对萃取精馏工艺进行双目标优化；阐明动态控制结构设计与经济性之间的规律，对于低碳醇共沸物的分离工艺，动态控制难度随经济性的升高而增大，为实现三元两两共沸物的萃取精馏过程提供策略与依据。本项目通过将基础实验、理论计算和过程模拟研究相结合，从热力学相行为、分子作用机理两方面分析萃取剂与共沸混合物之间的构效关系，深入认识存在于萃取精馏中的微介观分子结构与宏观特性及工艺参数的规律，针对不同的三元共沸体系设计合适的工艺方案与控制策略，对三元两两共沸物系的分离具有重要指导意义。