Study on the flow and collision characteristics of catalyst particles in FCC reactor

Abstract

Fluid Catalytic Cracking (FCC), a typical fluidization technology, faces serious issues of catalyst particle attrition and loss. Attrition is an important cause of catalyst loss. Due to the small particle size and complex flow process inside the reactor，it is difficult to conduct experimental research on it. The flow, collision and attrition characteristics of catalyst in the reactor are still unclear. This study established a geometric model of a catalytic cracking unit and used CFD-DEM bidirectional coupling numerical simulation method to study the flow and collision characteristics of catalyst particles in the catalytic cracking unit. The result indicate that particles collide with the wall most frequently， with an average collision frequency of 141,501.89 Hz. The particle wall collision frequencies above the nozzle, at the top of the riser, and in the cyclone separator are the highest, with an average collision frequency of 244.90 Hz, 1441.2 Hz, and 3571.15 Hz, respectively. Strong single collisions and slight continuous collisions of large size particles often occurred in the device. For small particles, the difference in strength between each collision within the device is not significant.