Exergy analysis of petroleum refinery hydrogen network integration based on reaction system

High-purity hydrogen is a crucial input in a crude oil refinery to upgrade several products. For this reason, the effective hydrogen management is necessary to satisfy hydrogen requirements. On the other hand, adding exergy analysis to the hydrogen pinch analysis especially for refinery plants, where hydrogen reacts under high temperature and pressure, helps improve the efficiency of unit by overcoming the lack of pinch analysis. The aim of this study is the simulation and exergy analysis of reactors within hydrogen network integration of a petroleum refinery retrofitted by pinch analysis before. Two hydrogen production and four consumption units were considered and simulated by Aspen Plus, and then the exergy efficiencies were calculated. Low exergy efficiencies were determined in the hydrogen production and hydrodesulfurization units, whereas the separation of excess hydrogen from the desired product considerably effected on the efficiency. The results also show that not only the hydrogen demand of reactors has to be reduced, but also the hydrogen recovery and purification is very important for the increase in efficiency. Although the processes are carried out at the high operating conditions, the reactions significantly affect the total exergy flow rate.