CFD Studies on Efficacy of Flow Modulation in a Hydrotreating Trickle-Bed Reactor

Hydrodesulfurization (HDS), a pivotal process for sulfur removal that is essential in deep processing of crude oil, is typically carried out in steady-state trickle-bed reactors (TBRs). Being familiar with such an operation, researchers are now investigating the benefits of flow modulation strategies in TBRs for improved conversion efficiency. In this work, a computational fluid dynamics model of a hydrotreating TBR is developed to delineate the efficacy of flow modulation in a HDS reaction system. Fast and slow modes of on-off and min- max flow modulations with different split ratios are compared with time-averaged continuous operation for reaction conversion. On-off and min-max flows resulted in relative improvement in conversion by 36 and 19%, respectively. Combined analysis of reaction conversion improvement along with an oscillating pressure drop revealed the efficacy of fast mode on-off strategy in maximum conversion of the considered system at the expense of lower pressure drop undulations.