Design of Inter-Plant Water Networks on Mathematical Approach

This paper aims to develop a general mathematical formulation for integrated design of inter-plant water networks. Based on the superstructures of all possible design options for processing facilities, e.g. water-using units, water mains, and receiving tanks, the design problem is formulated as a mixed-integer nonlinear program (MINLP), from the bilinear terms in balance equations and binary variables in operating constraints. The formulation can be used to apply various integration schemes by imposing the additional constraints, and five of them are considered in the present study with the objective to minimize the freshwater consumption. A representative example is provided to illustrate the application of the proposed MINLP formulation.