考虑工况变迁和兼顾运行的换热网络优化设计

Optimum design of heat exchanger network considering work conditions and operation

基于固定工况设计的换热网络无法保证变工况下的运行性能,以换热网络的运行优化和动态设计为出发点,提出了换热器旁路调节的方法,结合Grossmann的换热网络分级超结构模型,建立了换热网络旁路调节的数学模型和求解策略。利用蒙特卡罗随机技术和最速下降法混合优化策略获得了最佳旁路开度,保证了工况迁移时换热网络的运行性能。实例应用表明:旁路调节大大增加了换热网络的柔性,降低了运行费用。合理调整旁路开度可使得换热网络的运行始终处在较优状态,获得显著的经济效益。

The heat exchanger network designed on the basis of fixed work conditions can not guarantee the operation performance while work conditions are changed. Considering the operation optimization and dynamic design of heat exchanger network,the by-pass adjustment model of heat exchanger was proposed. The by-pass adjustment mathematical model and its solving algorithm were given,which was based on Grossmann heat exchanger network stage-wise superstructure model. The best by-pass adjustment fractions of heat exchanger network were resolved by the optimum strategy combining the steepest decent method and Monte Carlo random technology,which ensured large flexibility and low operation cost while the work conditions were altered. A practical instance shows that the by-pass adjustment ensures a heat exchanger network with higher flexibility while the operation cost is lower. Heat exchanger network can work well by adjusting by-pass fraction reasonably,and get better economic returns.