Hiroki Koyama

Commercial experience in vacuum residue hydrodesulfurization

Abstract Mizushima Oil Refinery of Japan Energy Corporation has succeeded in a high conversion operation ofvacuum residue in the residue hydrodesulfurization unit equipped with the fixed bed reactors. To complete a sixmonth cycle operation, hot spot occurrence, pressure-drop build-up, and catalyst deactivation had been the most important subjects to be solved. The commerical operation has demonstrated that good liquid distribution, which is obtained by uniform catalyst loading, an appropriate catalyst shape, and good liquid distributors, prevents hot spot occurrence. Dispersing solids throughout the reactors by an appropriate catalyst combination has been effective to control the pressure-drop increase in the first bed which is caused by plugging. Activity tests of the spent catalysts showed that the catalyst in the last bed was most deactivated due to coke fouling. It has been demonstrated that controlling the conversion in each bed reduces coke deactivation in the last bed.