含低碳醇共沸物系的压敏性及其变压精馏分离策略

In industry, there will produce a lot of azeotrope with low carbon alcohol , and it is hard to achieve effective separation by ordinary distillation. Pressure swing distillation has a very broad application in the separation and purification of azeotropic mixtures due to its superiorities of no third solvent introduced and energy saving. The feasibility of azeotropic systemsis is one of crucial factors in enabling the Pressure swing distillation process. The model of QSPR (Quantitative Structure Property Relationship) that azeotropic composition varies with pressure will be explored from microcosmic point of view and pressure sensitivity model of the binary azeotropic systems containing lower carbon alcohols will be established in this project. Different type of t-x-y phase diagrams will be investigated and the characteristics of deviating of azeotropic composition varying with pressure can be determined. The rule that the type of t-x-y phase diagrams effect the operating parameters of two columns in pressure swing distillation process will be clarified. Strategy and basis for realizing pressure swing distillation of binary azeotropic systems containing lower carbon alcohol will be provided. Temperature region are divided based on the temperature distribution characteristics of pressure swing distillation with different heat integration at steady state, so the effect of temperature control point in different regions on the performance of the control structures facing disturbance will be studied systematically. The method of the selection of temperature control point with multi-peak in temperature distribution slope will be established. The optimal deadtime of temperature and composition controller in control schemes with different heat integration will be explored based on tuning method of PTn model in control loop, the dead time model of temperature and composition controller will be established, so the accurate inference of the purity for key components and the modeling and optimization of effective dynamic control scheme can be realized.

工业生产中往往会产生大量含低碳醇共沸物，普通精馏难以实现其有效分离。变压精馏由于不引入第三组分、能耗低等优势被广泛应用于共沸物的分离与纯化，其中共沸体系的压力敏感性决定变压精馏工艺的可行性。项目拟从微观角度探究压力影响共沸组成偏移的机理，建立含低碳醇二元共沸体系的压力敏感性QSPR（定量构效关系）模型；考察不同类t-x-y相图共沸组成随压力偏移的变化特性，阐明其对变压精馏工艺中两塔参数的影响规律，为实现其变压精馏过程提供策略与依据。根据稳态条件下变压精馏不同热集成工艺中塔内温度分布特性，等分温度区域，系统研究不同区域内温度控制点对控制结构处理扰动能力的影响，建立温度分布斜率多峰值的温度控制点选择方法；基于控制回路中控制器的PTn调谐方法，探究不同热集成控制方案中温度和组成控制器的最优滞后时间，建立温度和组成控制器滞后时间模型，实现关键组分纯度的准确推理及有效动态控制方案的建模优化。

变压精馏在压敏性共沸物的分离中具有重要地位，广泛应用在化工、制药等行业。项目重点研究了含低碳醇共沸物系共沸特性的实验，建立定量构效关系模型，基于研究结果进一步设计并优化了相关物系的变压精馏分离与控制工艺，主要内容包括：（1）基于实验获得含低碳醇共沸物系的汽液相平衡数据，由t-x-y相图考察待分离共沸物系的相行为，确定共沸组成随压力变化的规律，为设计变压精馏分离含低碳醇共沸物系的工艺提供了依据；（2）基于密度泛函理论分析分子间相互作用规律，由σ-profiles谱图和计算得到的相互作用来定性判断组分间氢键的形成、定量分析组分间的相互作用强度，并利用相对挥发度验证量子化学计算结果的准确性和一致性；（3）基于遗传算法和多元非线性回归法，建立含低碳醇共沸物系共沸特性定量构效关系模型，实现共沸温度、共沸组成和相对挥发度等关键共沸物系特性的精准预测；（4）基于可行性分析和序贯迭代法，设计常规变压精馏工艺，耦合节能技术，开发出经济高效的变压精馏工艺分离含低碳醇共沸物系；（5）开发变压精馏控制结构，解决低自由度变压精馏工艺控制困难的问题。项目的研究丰富完善了含低碳醇共沸物系基础，基于量子化学计算，精准预测共沸特性，对变压精馏分离共沸物系的过程模拟设计和动态控制具有显著的促进作用。