CFD Simulation of Fluid Dynamics in a Gas-Solid Jetting Fluidized Bed

Abstract

A thorough understanding of fundamental parameters, such as transient and time-averaged gas and solid velocities, is helpful for designing and manipulating the gas-solid jetting fluidized beds. In this study, a new two-fluid model developed in our group is used to investigate numerically the gas and solid velocities in the gas-solid jetting fluidized beds by adding the user-defined Fortran subroutines in the platform of CFX 4.4, a commercial CFD software package. Simulation is carried out in a two-dimensional fluidized bed 2.0 m high and 0.3 m wide equipped with a nozzle in the centre at the inlet. Resin, belonging to Geldart B Group, is selected as the solid material. The numerical results show that the solid movement is predominantly upward in the center of the bed, whilst it is primarily downward in the outer region of the bed. Particles exchange between these two regions across their neighboring boundary. Gas interchange between the jet and the emulsion phase becomes obvious with the jet evolution. The time-averaged distributions of gas and solid velocities in the bed are greatly influenced by jet gas velocity, and the effect of the static bed height can be ignored. These numerical computations provide helpful information for designing and scaling up the jetting fluidized bed.