AXIAL-DISPERSION CHARACTERISTICS IN 3-PHASE FLUIDIZED-BEDS

The effects of liquid and gas velocities, liquid viscosity and surface tension, particle size and column diameter on the axial dispersion coefficients (D(Z)) of liquid phase in three-phase fluidized beds have been determined in two large (0.254 and 0.376 m-I.D.) columns. Tap water, carboxymethyl cellulose (CMC), Triton X-100 and ethanol aqueous solutions were used as the liquid phase; air as the gas phase and four different sizes of glass beads as the solid phase. The coefficient increases with increasing gas and liquid velocities in three phase fluidized beds. Whereas, the effects of liquid surface tension and liquid viscosity on D(Z) are found to be small. The axial dispersion coefficient decreases with increasing particle size and it sharply increases with increasing column size. The axial dispersion coefficients in terms of the Peclet number in the bubble coalescing and disintegrating regimes in three phase fluidized beds have been correlated based on the isotropic turbulence theory.