Gas flow patterns in spouted beds

Profiles of local spout gas velocity, in both radial and vertical directions, were determined with a Prandtl tube, and of annulus gas velocities from static pressure measurements. It was deduced that the parameter governing the spout gas velocity is the momentum transfer rate at the gas inlet, and not particle characteristics. The results also showed evidence of downward gas flow in the annulus and thus recirculation of gas in the vicinity of the entrance nozzle, which is an hitherto unknown aspect of the spouted bed gas flow pattern.