SUSPENSION OF SOLIDS IN MECHANICALLY AGITATED CONTACTORS

A theoretical equation for predicting the minimum stirrer speed required to keep the solids in suspension in an agitated vessel was reported in literature. The validity of this equation was checked with one type of stirrer, namely 8-blade flat turbine. In the present work, the equation has been modified so as to include the flow pattern generated by different impellers, namely disk turbine, pitch turbine downflow and propeller. Also the drag coefficient and a suitable correction factor in terms of solids concentration have been incorporated in the equation. The modified equation is compared satisfactorily with the data reported in literature. It has been observed that if mean mass diameter is used, the equation can be extended to include size distribution.