基于全周期持续节能的换热网络滑动窗口分析与裕量缓释优化控制

Sliding window analysis and slow-release margin optimal control for heat exchanger networks based on full cycle sustainable energy saving

换热网络是过程系统节能降耗的关键,对于给定换热网络其操作条件及生产要求等常发生变化,尤其是换热器普遍存在缓慢结垢现象,导致换热网络的运行参数偏离设计值,甚至难以满足生产操作要求。为此设计时一般留出一定的面积裕量,并通过旁路控制实现对面积裕量的在线调节。本文针对换热网络运行的全周期,以持续节能为目标,提出一种裕量缓释的优化控制方法。首先,针对换热网络整个运行周期,结合滑动窗口算法分析缓慢结垢现象与优化控制的关系,得出一种换热网络全周期持续节能的控制策略。然后,在划分的每个滑动窗口内以提高控制性能为目标,实现换热网络的在线优化控制。进而针对换热网络的全运行周期,以持续节能为目标,研究一种裕量缓释优化方法,优化求解每个窗口内可利用的换热网络面积裕量。最后,提出一种以全周期持续可控为目标的换热网络裕量缓释优化控制方法。结合实例说明采用本文提出的方法实现了全周期持续可控同时兼顾了各时间窗口内系统的动态控制性能。

The heat exchanger network is the key energy-saving equipment for chemical process systems.During the operation of the heat exchanger network,the production requirements and operating conditions often change,especially the phenomenon of fouling resistance in heat exchangers,which make the operation parameters of the heat exchanger network deviate from the set value and difficult to satisfy the operation requirements.The certain area margin is usually set in the design stage,and the bypass control is an important method to adjust the margin online.During the full cycle of heat exchange network operation,continuous energy conservation was taken as the optimization objective and an optimal control method of slow-release margin was presented.Firstly,according to the whole operation cycle of heat exchange network,combined with sliding window algorithm,the relationship between the fouling resistance and the optimal control was analyzed,and a control strategy of continuous energy saving in the whole cycle of heat exchange network was obtained.Then,the online optimal control of the heat exchanger network was realized with improving the control performance in each sliding window.Considering the sustainable energy saving of the whole operation cycle of heat exchange network,the slow-release margin optimization method was proposed,the optimal solution of the available margin in each sliding window was obtained.Finally,a slow-release margin optimization control method for the heat exchanger network was proposed with the optimization of the continuous controllability target in the whole cycle.Results showed that the proposed method not only can realize the continuous controllability in the whole cycle but also considers the dynamic control performance of each sliding window.