(60l) Investigation of Pressure Drop in a Three-Phase Moving Bed

Heterogeneous reactions widely exist in chemical industries. Dispersed principles of different heterogeneous reactions result in the developments of various multi-flow reactors, e.g., the fluidized bed for polymerization, the trickle bed for hydrocracking of cat-cracked gasoil and vacuum gasoil. Therefore, confronting so many kinds of heterogeneous reactions, and constant demands of increasing the product qualities and decreasing the process energy consumption, developing new multi-phase reactors is always necessary and significant. Therefore, a novel moving bed reactor concept based on concurrent downflow of gas, liquid, and solid phases is proposed in this study. It is supposed that this new reactor will not only have the same characteristics with a conventional moving bed reactor in which continuous catalyst regeneration is feasible, but also has the advantages that local turbulent intensity of gas phase and liquid phase, as well as the heat and mass transfer rates can be enhanced by moving particles.

Based on a self-established cold flow experimental device, the pressure drop in a concurrent downflow three-phase moving bed was investigated under a wide range of gas, liquid, and solid flow rates during dynamic and steady-state operation. The results showed that for the startup of the three-phase moving bed, since the first bed layer packed by fall-falling of particles had lower voidage, it would take at least one bed volume time to make the voidage in the bed reach the steady-state. Under steady-state conditions, the pressure drop increased with the increase of gas and liquid mass flow rates and decreased with the increase of solid flow rate. Furthermore, it was found that the liquid distribution in the bed improved with solid flow rate. The experimental data obtained in this study was used to develop a correlation to predict the pressure drop in a three-phase moving bed with an average relative error of 3.3%.