Comparison of jetting phenomena in 30-cm and 3-m diameter semicircular fluidized beds

Jetting phenomena in a 30-cm and a 3-m diameter semicircular transparent cold flow models were compared. Momentum dissipation, jet penetration depth, and jet velocity profiles were studied by visual observation and pitot tube traverse. Gas interchange between the jet and the emulsion phase of the fluidized bed was investigated by injection of tracer gas helium or carbon dioxide. The two-phase Froude number first proposed empirically to correlate the jet penetration depth was found to be still applicable for large jets up to 255-mm in diameter. A theoretical basis based on buoyancy is suggested for the applicability of the two-phase Froude number. Extension of the Froude number to apply in the case of two-phase jets where jets also carry solids and in the case of concentric jets is also outlined. Not only the gas velocity profiles in the jet are similar, tracer gas injection data indicated that gas concentration profiles in the jet are also similar as well.