A Systematic Methodology for Retrofit Analysis of Refineries Preheat Trains with Variable Heat Capacity and Exchangers Fouling

Energy demand for is increasing globally, pushed by increasing economy development and higher population. Over the past decades, energy consumption increased extremely. Petroleum industries are energy consuming processes, representing half of the energy consumption in typical industries. In order to decrease the energy consumption in the furnace and consequently decrease the overall energy consumption in the refinery, it is required to maximize the temperature of the crude oil before entering the furnace by increasing the efficiency of the preheat train. Revamping can enhance and maximize efficiency of energy to boost production, decrease the operating costs, and relax the environmental consequences. Maximum energy efficiency helps mitigate the climate change impact by cutting greenhouse gas emissions (SDG #13 Climate Action). Literature is rich in approaches and methodologies for retrofit however two main aspects are ignored including dependence of heat capacities on temperature and composition, in addition to exchanger fouling. Overlooking these aspects may lead to impractical retrofit solution, i.e. predicted energy savings are not achievable for the predicted retrofit modifications. This study proposes a systematic methodology for analyzing the revamping of refineries preheat train accounting for variable heat capacities and heat exchangers fouling. The methodology is based on Pinch Analysis and introduces two modifications to the literature revamping techniques, variable heat capacity of process fluids and fouling of exchanger equipment. This methodology is expected to produce more robust results and accurate revamping modifications that will lead to feasible solution. A case study applying the new methodology has led to an additional decrease in the cost of the furnace fuel by approximately 508,718 dollars/year with a payback period of 0.6 year. Moreover, the corresponding carbon dioxide emissions are cut by nearly 5594 tons/year.