On the basis of theoretical analysis and experimental study
the gas-solidinteraction in a concurrent downflow fast fluidized bed (CDFFB) with i. d. 140mm and height 5.8m was studied. In that case the gas-solids flow along the flow direction can be divided into three sections: the first acceleration section
the second acceleration section and the constant velocity section. The axial pressure gradient profile and the length of the first acceleration section were measured under different operating conditions (gas velocites in the range of 1.3 to 10m/s and solids circulating rates in the range of 30 to 180 kg/m2·s) and different particle properties (four kinds of particle were used).