基于相对?矩阵的精馏塔控制结构选择

Control structure selection for distillation columns based on relative exergy array

精馏塔是化工过程中的主要耗能装置之一,是一个典型的多输入多输出系统,具有强非线性、强耦合的特点。不同控制结构对精馏塔的操作性能有很大的影响,进而影响精馏塔的能效性能。相对增益矩阵(RGA)广泛应用于控制结构的选择,但RGA没有考虑控制结构选择对能效的影响。本文结合RGA和基于热力学第二定律的相对?增益矩阵(REA),分别以可控性和能效为具体指标,对精馏塔的控制结构进行选择,使所选的控制结构既有良好的可操作性以及节能效果。最后,以苯-甲苯精馏分离过程为应用背景,给出了具有最佳控制性能和能效水平的控制结构,并采用动态模拟验证可控性,分析稳态热力学数据验证能效性能。

Distillation column is one of the main energy consumption devices in chemical process, which is a typical multiple input and multiple output system with the characteristics of strong nonlinearity and strong coupling. Different control structures have a great influence on the operation performance of distillation column. And then the energy efficiency of distillation column is heavily affected. The relative gain Array （RGA） is widely used in control structure selection, but the limitation of RGA is that energy efficiency is not considered. In the paper, RGA is combined with Relative Exergy Array （REA） based on the second law of thermodynamics for the control structure selection of distillation column. Because the controllability and energy efficiency are considered simultaneously, the selected control structure has both good operability and energy efficiency. Finally, the proposed method is applied to a distillation colutan for benzene/toluene separation. The results show that the selected control structure provides the optimal control performance and energy efficiency by using the dynamic simulation and the steady state thermodynamics data analysis.