Cloud Height and Solids Distribution

In solid suspensions there is a distinct level to which most of the solids are lifted within the fluid even at speeds above Njs. The distance from the bottom of the vessel to this level is called the cloud height. The liquid below this height is solid-rich, while above it there is only an occasional visit by a few small solids. Hicks et al. (1993, 1997) and Bnjalski et al. (1999) have reported extensive data on cloud height and solid distribution. Bnjalski et al. (1999) also reported that the blending between the solid-rich and soUd-ftee portions is rather poor, and can result in a blend time as much as 20 times longer in the solid-free region than in the solid-rich volume. 

Bittorf and Kresta (2002) have applied a wall jet model successfiiUy to predict the cloud height data of Hicks et al. (1997) and Bnjalski et al. (1999). The proposed model for purely axial impellers (i.e., A310 or HE3) is 

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Cloud Height and Solid Distribution in Stirred Tanks... 

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