Hydrodesulfurization via heat exchanger network synthesis for ultra-low-sulfur diesel

In recent decades, the oil refining industry’s interest has been geared toward the production of clean fuels that contain fewer impurities such as sulfur and nitrogen compounds. Diesel hydrodesulfurization (DHDS) employed in light gas oil production has been widely applied to remove various impurities such as sulfur, nitrogen, and metal-organic compounds. In this study, the hydrodesulfurization process for the production of ultra-low sulfur diesel was simulated using the Aspen HYSYS hydroprocessing bed module. Then, exergy analysis was conducted. Since the exergy analysis indicated possible energy savings on the conventional DHDS, heat exchanger network (HEN) synthesis was applied to the process. By replacing the heater and cooler with two heat exchangers, 5% of utility energy could be saved compared to the conventional process. Since the modification was relatively simple, the developed HEN synthesis is feasible in the present DHDS.