Prediction of minimum slugging velocity, bubbling bed index and range of bubbling fluidization in cylindrical and non-cylindrical gas-solid fluidized beds

Abstract

A bubbling fluidization regime exists between the minimum bubbling velocity and the minimum slugging velocity. Experimental investigations have been carried out for the determination of the minimum slugging velocity and the range of bubbling fluidization for non-spherical particles in cylindrical and non-cylindrical beds. In the present paper, correlations have been developed for the prediction of minimum slugging velocity for gas-solid fluidization in cylindrical and non-cylindrical (viz. semi-cylindrical, hexagonal and square) beds for non-spherical particles fluidized by air at ambient conditions. The bed materials used have varied diameter (324 to 925 micron) and density (1500 to 4800 kg/m³). Experimental values of the minimum slugging velocity have been compared with the values calculated by the developed equations and also with the values calculated by Geldart’s equation. A fairly good agreement has been obtained between the calculated and the experimental values. Based on the experimental data, it is concluded that, under similar operating conditions minimum slugging velocity and minimum bubbling velocity are maximum in case of a semi-cylindrical conduit and minimum in case of a square one. It is further observed that the range of bubbling fluidization is maximum in case of a semi-cylindrical bed for the identical operating conditions.