Abstract
The present study defines the circulating fluidized bed using a binary solid mixture of fine powders (Geldart C) and coarse particles (Geldart A) as the Circulating Powder-Particle Fluidized Bed (CPPFB). The effects of the equilibrium water content of coarse FCC particles (63 ∼ 125 µm) on the performance of the CPPFB in terms of total solid entrainment rate of solid mixture and turnover time of fine aluminum hydroxide powders (3.0µm) in the bed were investigated under two different gas velocities and a starting hold-up of fine powders of 5 wt%. The performance of the CPPFB was improved greatly using FCC particles humidified with gas of higher relative humidity as 50 ∼ 80 %, where large entrainment rates and reasonable turnover time of fine powders were noticed. FCC particles humidified using low relative humidity gas (probably up to 35 %) proved not to be practically suitable for CPPFB as low entrainment rates and extremely high turnover time of fine powders were obtained at higher hold-ups of fine powders.
