The problem of improving structural flexibility of heat exchanger networks is to retrofit the configuration of a heat exchanger network whose flexibility does not meet the requirement and enhance its flexibility

so as to decrease its energy consumption caused by uncertain parameters. In this paper the key variables for controlling flexibility of a heat exchanger network are identified by a flexibility analysis method. The worst operation point is established in the range of the uncertain parameters. Then two subproblems of temperature difference key variable and heat load key variable are solved to configure the corresponding e-quivalent structure

and the flexibility of the network can be efficiently improved

by using the strategies of shifting

splitting and decreasing heat load.