Multi objective optimization of the water network in an oil refinery using Reuse meth od

Water system integration can minimize both the freshwater consumption and the wastewater discharge of a plant. In industrial applications, it is the key to determine reasonably the contaminants and the limiting concentrations, which will decide the freshwater consumption and wastewater discharge of the system. As a case study, the water system in an oil refinery is integrated. According to the requirements of each water using process on the water used in it, the contaminants and the limiting concentrations are determined. Then, the optimal water reuse scheme is studied based on the water network with internal water mains. Next, multi objective optimization is considered. In the case that objective function is minimization of the fresh water, water usage is reduced by 44% and when objective function changes to simultaneous minimization of fresh water and total cost, water usage is reduced by 47%.