A 200mm×50mm×1450min two -dimensional spout -fluidized bed with a central draft tube was used to study the effect of geometry and operating parameters as well as phys ical properties of material on solids circulation rate. Four different solids and draft tube sizes were used in this study. With increasing gas feed rate

the gap between the draft tube inlet and conical distributor (R)

the distance between the nozzle and the draft tube inlet (L1)

the draft tube area

and the solid circulation rate will be increased. The draft tube height has no effect on solids circulation rate. A quantitative correlation

derived from the concept of the gravity flow of particles through the gap (R) and consisting of geometric

operating

as well as material parameter

was proposed for predicting the solids circulation rate of this type of bed.