A Pilot-Plant Simulation of the Influence of the H2/H2S Ratio on the Efficiency of a Commercial Hydrodesulfurization Plant

Due to a low content of H2 in the makeup gas which was added into the recirculation stream, the hydrodesulfurization (HDS) efficiency of the commercial unit is continuously decreasing. To maintain the required level of sulfur in the products, both elevated temperature and a space velocity decrease were applied. This situation ends with a severe capacity reduction. The observed decline in HDS efficiency is due to the disturbed H2/H2S ratio in the recycle gas. This was confirmed by the pilot-plant studies of the influence of the reaction parameters on the HDS efficiency as a function of H2 purity in the gas phase.