Solids Circulation Rate and Holdup within the Draft Tube of a Spouted Bed

Characteristics of a spouted bed with draft tube were measured in terms of solids holdup in the draft tube, solids circulation rate and gas flow rate in the annular section. Using iron powders as the bed material, an induction transducer method was developed to obtain the solids holdup. It was found that there are two kinds of solids flow regimes along with the change of gas velocity in the draft tube. One is the dilute-phase flow regime, where the solids holdup is almost insensitive to the gas velocity and no descending flow of solids exists, and the other is the densephase flow regime, where the solids holdup is affected by the gas velocity and the particles are flowing downward. In addition, the solids holdup in the draft tube, solids circulation rate and gas flow rate in the annular section were experimentally measured by changing gas throughput and bed weight as operating parameters, and also by changing tube separation distance and draft tube diameter as design parameters.