Water and Wastewater Minimization in the Oil Refinery through Water Pinch Analysis Using Double Contaminants Approach

Water pinch analysis is an opportunity for chemical, civil and environmental engineers to analyze water-using processes before designing and operating. Furthermore, it can minimize the freshwater utility and wastewater generation. This study aims to find an appropriate way to minimize water utility in the petrochemical and petroleum industries due to high rate of water consumption. For this purpose, Tehran petroleum refinery has been well studied. In this research, three contaminants including suspended solid (SS), hardness (H) as well as COD have been considered as key contaminants and three processes, which use vast amount of water including desalter, cooling towers as well as portable; plant and fire were selected to analyze the water network. These key contaminants were analyzed two by two simultaneously based on their mass transfer. In other words, mass transfer of a contaminant was analyzed with respect to another one. The results show that, in the targeting for minimization based on SS and H, the amount of required water is reducedl42.74 m(3)/h, which is about 42%. This amount for SS and COD is equal to86.3 m(3)/h (26%) and for COD and H is124 m(3)/h (37%). Analyzing the method shows that the method based on double contaminants gives more precise results rather than single contaminant. Therefore, it is suggested that more contaminants and operations are considered for study of water networks and reach water utility optimization based on key contaminant as well. Besides, mathematical optimization methods and computer programming can be used to obtain the results that are more exact.