Radial liquid dispersion and bubble distribution in three-phase circulating fluidized beds

The liquid dispersion and bubble distribution in the radial direction have been investigated in the riser of a three-phase circulating fluidized bed whose diameter is 0.102m and 3.5m in height. Effects of gas and liquid velocities and solid circulation rate have been determined. It has been found that the radial distribution of bubbles is related closely to the liquid dispersion in the radial direction. The size and rising velocity of bubbles tend to increase as the radial position approaches to the center of the riser. The bubble size increases with increasing U-G, but it decreases with increasing U-L or G(S) in all radial positions. The radial dispersion coefficient of the liquid phase increases with increasing U-G or G(S), however, it tends to decrease with increasing U-L. The value of D-r has been well correlated in terms of dimensionless groups based on the isotropic turbulence model.