BED EXPANSION CHARACTERISTICS AND TRANSITION VELOCITY IN TURBULENT FLUIDIZED-BEDS

The bed expansion and the transition velocity from slugging to turbulent fluidized beds of glass beads (dp = 0.362 mm) have been determined in a 0.1 m-I.D. × 3.0 m high Plexiglas column. The bed expansion in the slugging and turbulent flow regimes has been determined from the bed voidage obtained by the mean pressure drop in the bed. Change of slope in a logarithmic plot of bed voidage against gas velocity has been utilized to determine the transition velocity from the slugging to turbulent flow regimes. Bed expansion in both regimes was found to be smaller than that predicted from the two-phase theory. The effects of particle properties and column size on the transition velocity to the turbulent flow regime have been determined. The flow regimes and corresponding transitions spanning from the bubbling to dilute phase flows have been quantitatively predicted in terms of the Reynolds and the Archimedes numbers based on the data of the present and previous studies. © 1990.