CFD-DEM simulations of a fluidized bed with droplet injection: Effects on flow patterns and particle behavior

As one of the most preferred technologies, fluidized beds with droplet injection have been widely applied in a variety of industries attribute to the advantages of excellent mixing effect as well as consecutive interphase contact. However, pronounced slugging and gas channeling may occur with the existence of droplets, where a large proportion of bed solids would be lumped together. This study focused on the hydrodynamics and cohesive-like characteristics of solid particles in a pseudo-2D droplet gas-solid fluidized bed via two-way coupled CFD-DEM numerical simulations with the consideration of droplets coating process and liquid bridge force. Results revealed that the existence of droplets would lead to poor fluidization characteristics. It could be summarized that the increase of surface tension would lead to inadequate mixing. At the same time, larger value of liquid viscosity would cause a slower particle motion, while cases that exhibited vigorous fluidization corresponded to smaller values of viscosity. The influences cast by different contact angles were also studied and results showed that choosing an appropriate contact angle is of paramount importance to the optimization of the fluidization quality. It was also found that the more droplets injected, the worse the mixing behavior, while changing the number of droplets injected had no significant effect on the flow pattern and particle motion.