消除气相分割的多产品反应隔板精馏塔优化与动态调控机制研究

In order to realize process intensification in petrochemical industry, this project is aimed to combine reactive distillation and thermally coupled distillation process. However, the “bottleneck” resists in the uncontrollable vapor split. To solve this problem, the classical two-way thermal coupling is thermodynamically converted to one-way liquid-only transfer stream, which results in the reactive dividing wall column without vapor split (NV-RDWC). The steady and dynamic model of NV-RDWC is developed based on non-equilibrium model, by considering the coupled mechanism of reaction and distillation. An effective and systematic method by employing generalized disjunctive programming is proposed to optimize the structural and continuous variables. Besides, multi-loop PID control structures and model predictive control (MPC) is designed to investigate the dynamic behavior of the integrated system. And the key parameter-liquid split ratio’s optimization regulatory mechanism is clarified when the system is subject to feed and set point disturbance, which generates the optimally regulatory mechanism model. Finally, in order to validate the NV-RDWC’s effectiveness and operability advantage, steady and dynamic experiments are conducted by employing typical reactive distillation system in petrochemical industry. The implementation of this project has important scientific significance on the clarification of reactive distillation process intensification mechanism, the establishment of combinational optimization and regulatory control method, which could provide theoretic foundation and technique support for application of the new NV-RDWCs in petrochemical downstream industry.

本项目通过结合反应精馏与热耦合精馏过程实现石油化工过程强化。为解决气相分割不可调控的“瓶颈”问题，将气相分割伴随的气液相耦合流股热力学等价为液相耦合流股，构思了消除气相分割的反应隔板精馏塔(NV-RDWC)。在考虑反应与精馏过程耦合机制的基础上，建立了基于非平衡级的稳态与动态数学模型，利用析取规划发展多参数组合优化的系统工程方法，并通过PID多回路与模型预测控制研究系统的动态行为规律，阐明关键调控参数-液相分割比在系统受到扰动时的优化调控机制并建立机理模型。为了证明过程强化的有效性与消除气相分割后的操作优势，应用典型石化工业物系进行稳态与动态实验。本项目的实施对反应隔壁精馏系统耦合强化机制揭示、组合优化与关键参数调控方法建立具有重要科学意义，可为NV-RDWC的在石油化工下游产业应用提供理论基础与技术支撑。

反应与分离过程的集成是实现过程强化的重要手段，其优势集中体现在产品转化率与收率的提高以及能耗的显著降低。反应隔壁精馏作为反应精馏与热耦合精馏的进一步强化与集成，是过程耦合强化的应用典范，对于化工反应高效转化与分离过程节能具有重要意义。然而反应隔板精馏塔耦合系统表现出高度的复杂性与强非线性，反应动力学与精馏热力学过程高效合理匹配、系统的稳定性、多参数优化与关键参数优化调控是系统耦合复杂特性的核心问题，也是制约反应隔板精馏塔工业应用的主要原因。为消除隔板精馏塔操作过程中气相分割比的不可调控的“瓶颈”问题，采用将气相分割热力学等价转化为液相分割的学术思想，首次构思出消除气相分割的多产品反应隔板精馏塔形式。以甲酸甲酯水解过程与碳酸二甲酯酯交换过程为研究对象，同时采用随机优化算法与广义析取规划模型，解决了多种反应隔壁精馏过程中的多参数优化问题，实现了反应与精馏过程的高效匹配。在优化设计点的基础上，对于多种过程耦合强化流程分别设计了多回路PI控制结构与基于模型的先进控制结构-线性模型预测控制，阐明了液相分割比在消除气相分割的反应隔壁精馏过程控制中的优化调控机制，并证明了模型预测控制能够有效提升复杂耦合系统的控制性能。采用稳态与动态实验对耦合强化过程高效匹配与动态行为规律进行了验证。最后以反应精馏过程动态运行高维数据为基础，通过引入监督学习-卷积神经元网络模型，构建了过程运行状态的智能识别系统。项目的研究成果是反应与精馏耦合强化系统的优化与控制重要理论基础，形成了采用过程系统工程方法实现过程强化的研究范式，并对典型化工流程的节能降耗与实现行业“碳达峰、碳中和”提供了重要技术支撑。