Simultaneous Optimization Of Multi-period Heat Exchanger Networks And Cleaning Schedule Based On Continuous Energy Saving

In petrochemical industry,operating conditions of heat exchanger networks(HENs)are always changed,which particularly fouling-induced heat resistance keeps increasing over time.To overcome variation of operating conditions,several optimizing methods on design and retrofit of multi-period HENs are available with no consideration of fouling effect on HEN.The inevitable HEN fouling and increase of heat resistance will drive operation deviate from optimum value and make it difficult to sustain energy saving.At the same time,considering the effect of fouling resistance on efficiency of HEN,some researches proposed a method to optimize cleaning schedule of HENs.However,these methods mostly studied on the optimization of HENs based on the steady state model without considering the dynamic process and the optimization of multi-period HENs.In this work,for the multi-period HENs optimization,the continuous effect of fouling resistance is analyzed,and to minimize the accumulative total costs,a methodology for multi-period HENs synthesize is proposed.Firstly,the margin design of HENs is optimized by targeting total accumulative cost based on the dynamic mathematical model of fouling resistance,and a method of multi-period HENs retrofit is proposed for continuous energy saving.Meanwhile,the continuous effect of fouling on HEN and the influence of cleaning schedule are considered simultaneously by minimizing the accumulative cost.Finally,both considering the variations of operation conditions and the fouling of equipments,a multi-period HENs and cleaning schedule model is established as well as a simultaneous optimization design of multi-period HEN and cleaning schedule is proposed for continuous energy saving.