In order to achieve sustainable energy saving of heat exchanger network in the life cycle

bypasses were set in the network to increase its control degree of freedom

while a certain margin was designed to provide operating space of optimal control.To better use bypass adjustment and margin of operating space

an optimal control approach method based on dynamic model of heat exchanger network was presented and combined with existing conventional control loop

not only expanding the feasible region of optimal control

but also meeting the accuracy requirements of the original conventional control loop.The cumulative cost minimization of heat exchanger network within a certain period was considered as the objective function

while considering the impact of disturbances on heat exchanger network.To meet the process conditions

the best bypass opening in the life cycle was solved in order to achieve sustained energy saving of heat exchanger network.Closed-loop correction

iterative and rolling implementation were adopted

and optimization was based on actual conditions.A global sub-optimal solution could only be arrived at every turn.However

the actual control result could achieve the optimum.Finally

a refinery's crude oil heat exchanger network was treated as the specific study object

illustrating the effectiveness and application prospect of the presented method.