换热网络中热口袋与精馏塔的热集成

Heat Integration of Heat Pockets and Distillation Columns in Heat Exchange Networks

在换热网络的总复合曲线上,当夹点之上出现内部局部热源或夹点之下出现内部局部热阱时会形成热口袋。通常热口袋中物流间相互换热,不需要公用工程提供热量。考虑将热口袋与精馏塔集成,以实现能量的多次梯级利用。针对精馏塔与热口袋的不同相对位置和热负荷状态,提出相应的6种集成方法。对某乙二醇装置换热网络中的热口袋与精馏塔的集成进行分析,提出集成优化方案,并使用Aspen HYSYS软件对优化前后的工艺参数进行模拟。案例分析结果表明,通过热口袋中热量的多次梯级利用,减少了装置的蒸汽用量,每年节省蒸汽费用8.52×106元,获得明显的节能和经济效益。

On the grand composite curve of a heat exchanger network,a heat pocket will form when internal local heat sources above the pinch point or internal local heat sinks below the pinch point appear. Usually the streams in the heat pockets exchange heat with each other,and so no utilities are needed. The heat integration between the heat pockets and distillation columns were investigated in order to realize the multiple cascade utilization of energy. Aimed at the different positions and heat duty of the heat pockets and distillation columns,six corresponding heat integration methods were presented. The heat integration between the heat pockets of the heat exchange network and the distillation columns in an ethylene glycol plant was analyzed,an integrated optimization scheme was proposed,and process parameters before and after the optimization were simulated by means of the Aspen HYSYS software. The results of the case study showed that the multiple cascade utilization of energy in the heat pockets can reduce steam consumption of the plant,saving about 8.52 million Yuan/a steam cost.