Gas discharge patterns in a large jetting fluidized bed with a vertical nozzle

The gas discharge patterns, a jet and a spout, generated by a vertical nozzle in an 8-m-high, 0.5-m-diameter jetting fluidized bed were investigated using frame-by-frame analysis and Sth VCD software analysis. The static bed height was varied from 0.38 to 0.66 m, and the nozzle jet velocity was varied from 16.1 to 64.26 m/s. A correlation was developed using experimental data to predict the transition of the flow pattern from a jet to a spout. The study shows that the major frequency in the power spectrum density function agrees with the jet collapse frequency measured by frame-by-frame analysis and Sth VCD software analysis. The major frequency in the power spectrum density function increases with increasing jet gas velocity. In addition, the jet velocity at the critical point in the curve of the major frequency versus the jet gas velocity corresponds to the gas velocity for the transition from a jet to a spout.