Abstract: In order to solve the problem that it is difficult to take into account both high solids holdup and uniform gas-solid distribution in the inlet distributor of the downer, a novel gas-solid distributor for particle concentration in downers was proposed based on the mechanism of gas-solid two-phase flow in downer. The performance of downer fluid mechanics was investigated by using the developed structural drag model coupled with computational fluid dynamics software. The simulation results showed that the simulation results of the structural drag model were consistent with the experimental data. Compared with the distributor in the literature, the novel distributor is more uniform with the design of subarea fluidization, Venturi type overflow pipe and funnel type. When the solids circulation rate was up to 700 kg/(m².s), the overall solids holdup could reach 0.06 with uniform gas-solid distribution. Furthermore, the solid circulation rate plays a more sensitive role in increasing solids holdup than the gas velocity.

Key words: downer, distributor, simulation, solids holdup