Energy and Water Management for Industrial Large-Scale Water Networks: A Systematic Simultaneous Optimization Approach

Water and energy management issues in process industries are generally related to the synthesis of heat integrated water networks (HIWN), because water and energy are inextricably intertwined in process water networks. The aim of this study is to present a novel mathematical programming model for HIWN synthesis problems and develop an efficient solution strategy. This research is an extension of our previous work, where the targeting of heat integrated water-using networks (HIWUN) has been addressed. In this model, wastewater treatment units and multiple contaminants are embedded, and the total annual cost (TAC) is optimized rather than targeting a simplified TAC. What is more, a three-step solution strategy is proposed to guarantee obtaining promising solutions. The freshwater consumption, the relaxed TAC (rTAC), and the TAC are optimized successively. Good initial points for the rigorous HIWN model in the last step can be generated by the minimizing the rTAC. Four examples including two large-scale examples are illustrated to demonstrate the applicability of the proposed model and the efficiency of the solution strategy. The results indicate that the proposed model is suitable for the synthesis of HIWN, and more significantly, better results for large-scale problems are achieved.