Estimating Just Suspension Speed for Stirred Reactors Using Power Measurement

Abstract

A simplified mathematical model was developed to predict the just suspended speed, NJS in a solid-liquid system by analyzing the net impeller power consumption to suspend solid particles. A fully baffled tank with an internal diameter of 400mm equipped with a standard Rushton turbine with a diameter of D=T/3 (133mm) was used in this work. Glass beads were used as the solid phase and distilled water was used as the liquid phase. Solid loadings were varied within the range of 0-27 wt%. Power consumption was measured using the shaft torque method. The predicted NJS values were in a good approximation to the experimental values using the Zwietering’s criterion with a deviation of 2 – 10%. The deviation was lower for higher solid concentrations.