During the operation of Heat exchanger network (HEN)

for operating conditions are always varied

the bypass optimal control is considered as an effective method to adjust the temperatures and saving energy. However

locations of bypasses are derived without the verification by the control theory. Therefore

it is very necessary to analysis the structural characteristics of heat exchanger networks. Firstly

based on the topology theory

the structural states configuration and array are presented by using the structural model of the HEN. Then

the HEN structural controllability

the structural control intension and redundancy degree are analyzed. The results indicate that the bypass on downstream is less controllability than that on upstream; structural control intension is affected by the corresponding bypass location; and the using of the coupling channel may affect the redundancy degree and the controllability significantly. The analysis of case study demonstrated this method can be used to testify the controllability of the HEN with bypass optimal control

and significantly reduce the analysis complication on complex structural controllability analysis. This method also indicated a novel idea for applying control theory on engineering process.