Abstract:

Due to the frequent occurrence of major chemical accidents at home and abroad and the increasing demand for energy saving and consumption reduction in the chemical industry, it is of great significance to study multi-objective optimization of heat exchanger networks(HEN) with more secure nature. Evaluation index method was employed to quantify the inherent safety explosiveness, toxicity and inventory for the HEN. Mathematical programming was used to establish a mathematical model of HEN synthesis considering inherent safety. Normalization method was used to obtain the objective function of economy and safety. The case study shows that when explosiveness index is considered, the heat exchange among safer process streams is preferred. When toxicity index is considered, the heat exchangers with toxic process streams are preferred to be eliminated. When inventory index is considered, the number and area of heat exchangers are preferred to be reduced. Then the explosiveness, toxicity, inventory and economy of HEN was optimized simultaneously. And the case study shows that the optimal HEN relies strongly on the selection of economic weight in the proposed objective function.

Key words: heat exchanger network, stage-wise, inherent safety, multi-objective optimization, Pareto front

摘要：

由于国内外重大化工事故的频发及化工行业节能降耗的需求日益迫切，研究本质更安全的换热网络多目标优化具有重要意义。采用评价指数的方法，对换热网络的本质安全易爆性、毒性、存量进行量化表征。采用数学规划法分别建立换热网络经济与本质安全易爆性、毒性、存量同步优化数学模型。采用归一化法构建经济和安全的目标函数。通过算例研究发现，考虑易爆性，倾向于不易爆流股间换热，减少易爆流股换热次数；考虑毒性，倾向于减少有毒流股流经换热器的次数；考虑存量倾向于减少换热网络的总存量。最后综合考虑易爆性、毒性、存量作为安全指标与经济同步优化，通过算例研究表明，多目标优化的最优换热网络在很大程度上取决于经济权重的选取。

关键词: 换热网络, stage-wise, 本质安全, 多目标优化, Pareto前沿