Radial solid mass flux profiles in a high-suspension density circulating fluidized bed

For external solid mass fluxes between 148 and 264 kg/(m2·s), at a fixed superficial gas velocity of 4.7 m/s, a dense bed was formed at the base of a 0.14-m ID circulating fluidized bed (CFB) riser. The apparent solid concentration in the dense bed was approximately 17 vol%. Radial solid mass flux profiles were measured at axial locations of 1.6 and 2.1 m. The net flow of solids was always upward at 1.6 m, and the maximum occurred at the riser wall. Net downflow was observed for 148 kg/(m2·s) at 2.1 m. Net flow at the wall was still upward for the other flux conditions, but the maximum shifted to an intermediate radial location near r/R=0.3. A qualitative description of the developing flow at the base of the riser is presented and used to interpret the profiles from previous studies.