Effect of superficial gas velocity on solid behaviors in a full-loop CFB

The effect of superficial gas velocity (Uf) on solid behaviors in a full-loop circulating fluidized bed is numerically studied using computational fluid dynamics-discrete element method (CFD-DEM). Specifically, the solid mixing and dispersion, solid residence time, solid force and velocity, and particle granular temperature are comprehensively explored. The results show that increasing Uf slows the solid mixing. The solid axial dispersion in the riser is dominated among that in the three regions. Besides, increasing Uf decreases the solid cycle time and leads to a more uniform solid residence time (SRT) distribution in the riser and dipleg. The fluid force is an order of magnitude smaller than the collision force. Increasing Uf shows distinctive influences on the rotational speed and translational velocity in the three regions. Moreover, increasing Uf suppresses the particle granular temperature. The average particle granular temperatures in the riser at four superficial gas velocities (i.e., 5.5 m/s, 6.0 m/s, 6.5 m/s, and 7.0 m/s) are 0.09326 m2/s2, 0.08040 m2/s2, 0.06531 m2/s2, and 0.05047 m2/s2, respectively. [Display omitted] •LES-DEM coupling approach is firstly used to study solid behaviors in a 3-D full-loop CFB.•Increasing Uf slows the solid mixing and suppresses the particle granular temperature.•Increasing Uf decreases the solid cycle time and leads to a more uniform SRT distribution in the riser and dipleg.•Increasing Uf shows different influences on the rotational speed and translational velocity in the three regions.•The solid axial dispersion in the riser is dominated among the three regions.