EFFECT OF ERUPTING BUBBLE DIAMETER ON GAS VELOCITY FLUCTUATION IN FREEBOARD OF A FLUIDIZED-BED

Axial and radial distribution of gas velocity fluctuation in the freeboard of a fluidized bed was measured by a hot-wire anemometer and analysed by a real-time correlator. Taking account of the analogy with steady turbulent jet behavior, experimental results are correlated by employing bubble diameter and height as parameters. An equation for T.D.H. estimation is proposed and close agreement is obtained with the values determined from Zenz's nomograph. These results clearly support a postulate that the decay of velocity fluctuation induced by bubble eruption at the bed surface is the major factor controlling the transport phenomena in freeboard. © 1980, Society of Chemical Engineers, Japan. All Rights Reserved.