The effect of gas properties on Group C⁺ fluidized bed reactor

The performance of a fluidized bed reactor depends mostly on the fluidization quality, which can be significantly affected by the gas properties, especially the gas viscosity and density. The effects of gas species on the fluidization properties such as minimum fluidization velocity, bed expansion, dense phase voidage, and pressure fluctuation of three typical types of Group C⁺ (nano-modulated Geldart Group C) particles, were carefully studied using five types of fluidizing gases and their combinations. With the increase of gas viscosity and density, argon possessed the lowest minimum fluidization velocity and the highest dense phase and total bed expansions, followed by air/nitrogen and helium, and trailed by hydrogen. Using two gas mixtures, the gas viscosity was singled out from the gas density and proved to play a more important role on the fluidization due to the increasing gas viscosity causing a more significant increase in the drag force on the particles. The smallest particles, 10 μm glass beads, had stronger cohesion than the 17 μm and 22 μm larger polyurethane particles and therefore exhibited a higher minimum fluidization velocity, lower dense phase and bed expansions, and larger pressure fluctuations.