不同操作周期下考虑结垢问题的换热网络优化

Heat exchanger network optimization considering fouling under different operation periods

换热网络优化一直是过程系统集成中的研究热点,而换热器结垢是换热过程中不容忽视的问题.基于结垢阈值模型,换热器中的结垢问题可通过流速优化、分流比优化以及清垢周期优化这3种手段进行改善.在某原油常减压预热网络的案例基础上,考虑换热器的结垢及压降问题,在不同的操作周期下分别采用这3种手段,实现对固定结构换热网络的优化.结果表明,3种手段均可不同程度地降低年度总费用,且节能效益随不同的操作周期有所改变.

Optimization of heat exchanger networks in process integration has been studied for many years. Fouling has a great impact on heat transfer in a heat exchanger. Based on fouling threshold model, fouling problem can be eased by three methods - flow rate optimization, split ratio optimization and cleaning schedule optimization. A case of crude oil preheat train is used to illustrate the effectiveness of the methods. In the case study, both fouling and pressure drop problem are considered. The three methods are used to optimize the fixed heat exchanger network under different operation periods. It turns out that the three methods can effectively reduce the total expenses and the amount of saved energy changes with different operation periods.