In a practical water using process

a temperature requirement exists. Thus

it is significant to consider the temperature constraint in water network integration to decrease the water and energy consumption at the same time. Besides

there are non-water process streams which only have temperature requirements in the process system. If these streams are integrated with water streams in the water network

better energy efficiency can be reached. In this paper

a method for optimizing water networks is proposed under the background of heat integration in whole process system. First

an LP model is established to obtain the initial status of the water network and stream data. Then

four rules for non-isothermal mixing are proposed by comparing the relative position of water streams with the background and whole process pinches to exclude the irrational non- isothermal mixing. Finally

the heat integration in the whole system is performed with minimal total annual cost as the objective function. A case study is used to show the feasibility of the method

which can get a decrease of 6.27% in the annual cost.