CFD approach in design of effective distributor for uniform dispersion of cohesive ultrafine particles in a downer reactor

Abstract

Downer reactor has been widely used in carrying out multiphase processes in the recent decade. The nature and introduction of particles in the downer has its own characteristics to achieve uniform and well dispersed flow. This creates a necessity to design a distributor for achieving uniform dispersion of particles in a short distance. The present study explores the use of CFD with different distributor configurations to design an effective distributor for dispersion of ultrafine cohesive particles. In the present study, the ultrafine cohesive powder considered is petcoke of mean particle size 60 μm and estimated Carr’s index of 30.83. The downer reactor is of 200 mm diameter and 8 m long. The solid particles are fed through a screw feeder above gas distributor. Different distributor designs are considered for assessing the dispersion using Fluent ANSYS v19.0. The results from the investigation indicate that there is a strong influence of jet velocities and pressure distribution in the distributor on dispersion of cohesive particles. The present study highlights the use of CFD in numerical experimentation in identifying the appropriate designs suitable for cohesive ultrafine particulate systems.