Individual phase holdups and radial dispersion of liquid phase in bubble column, liquid-and three-phase fluidized beds have been studied.
In three phase fluidized beds, water and glycerol aqueous solutions were used as the liquid phase; air as the gas phase and glass beads of seven different sizes (0.1-0.8 cm) as the solid phase.
Effects of liquid velocity (0-14 cm/sec), gas velocity (0-12 cm/sec) and particle size (0.1-0.8 cm) on radial mixing characteristics have been determined. In addition, the effect of liquid viscosity (1-60 mPa.s) on phase holdups has been determined.
Gas phase holdup increased with gas velocity but it decreased with liquid velocity and viscosity in bubble columns.
Liquid phase holdup decreased with increase in gas velocity but it increased with liquid velocity and viscosity in three phase fluidized beds.
The radial dispersion coefficient increased with gas and liquid velocities in the bubble coalescing regime. Whereas, it decreased with gas velocity in the bubble disintegrating regime.
The gas phase holdup and bed porosity data have been correlated with the dimensionless numbers.
The radial dispersion coefficient in terms of Peclet numbers has been correlated with the concept of the isotropic turbulence theory.