Flow regime transition and liquid distribution in a 3D concurrent downflow three-phase moving bed

Abstract

Based on a cold-flow experimental setup, the transition between trickle flow and pulse flow in a 3D concurrent downflow three-phase moving bed is investigated by the standard deviation of pressure drop and visual observations. Results show that at a constant gas flow rate, the trickle-to-pulse transition shifts to a higher liquid flow rate with the increasing solid flow rate because the particle moving inhibits the formation of local liquid blockage. Furthermore, an empirical model is proposed to fit the trickle-to-pulse transition boundary by correlating the dynamic liquid holdup at the boundary with the gas Reynolds number, the particle velocity, and the relative viscosity. Finally, the effects of the particle moving on the liquid distribution are investigated, which shows that the particle moving makes the liquid distribution more uniform when the solid flow rate is smaller than a certain value. But further increasing the solid flow rate, the liquid distribution becomes uneven.