Synthesis of Interplant Water-Allocation and Heat-Exchange Networks. Part 1: Fixed Flow Rate Processes

This paper is part 1 of a series dealing with the design of integrated interplant water-allocation and heat-exchange networks (IWAHENs), a special case of interplant network synthesis with multiple physical properties. Traditionally, the tasks of optimizing water-allocation networks (WANs) and heat exchange networks (HENs) were either performed individually or studied within a single plant. In this paper, a novel multiscale state–space superstructure is developed to capture all possible network configurations for the fixed flow rate (FF) IWAHEN designs with both direct and indirect integration schemes. In addition, our model has been simplified to deal with the interplant HEN design where the optimal utility network can be determined simultaneously. By properly addressing the interactions between different plants as well as the WAN and HEN subsystems, lower total annualized cost (TAC) can be obtained in all examples by solving the corresponding mixed-integer nonlinear programming (MINLP) model.