Axial dispersion coefficients in three-phase fluidized beds have been measured in a 0.152m-ID 1.8m high column by the two points measuring technique with the axially dispersed plugflow model.
The effects of liquid velocity(0.05-0.13m/s), gas velocity(0.02-0.16m/s) and particle size (3-8mm) on the axial dispersion coefficient at the different axial positions (0.06-0.46m) in the bed have been determined.
The axial dispersion coefficient increases with increasing gas velocity but it decreases with an increase in particle size and exhibits a maximum value with an increase in the axial position from the distributor.
The axial dispersion coefficients in terms of the Peclet number have been correlated in terms of the ratio of fluid velocities, the ratio of the particle size to column diameter, and the dimensionless axial position in the bed based on the isotropic turbulence theory.