Solids distribution in stirred slurry reactors: Influence of some mixer configurations and limits to the applicability of a simple model for predictions

The features of solids concentration distribution were investigated in baff led and unbaffled tanks of high aspect ratio, stirred with multiple radial, mixed-flow or axial impellers. In the baffled tanks the average profiles c an be predicted with the sedimentation-dispersion model regardless of impel ler type - in spite of slight systematic departures from the average trend at the impeller plane and/or midway between the impellers. This is hardly p ossible for the unbaffled tanks due to lack of physical foundation of this simple model. When the unbaffled tank is stirred with hydrofoil impellers, an inverted profile is even obtained. The mentioned departures and this las t anomalous behaviour are qualitatively discussed with reference to particl e-turbulence interaction.