Determination ofthe Shaft Speed Necessary for Suspending

Determination ofthe Shaft Speed Necessary for Suspending 

Again very different approaches can be found in this field, delivering various models for correlation or calculation. The reasons for this are 

Nevertheless, some general conclusions can be drawn, concerning the following parameters that have to be considered  

Among the models for calculation of the shaft speed needed for suspension, the equation of Zwietering [12] is based on numerous experimental results. The shaft speed necessary to reach a state where the particles are just suspended (njs) can be correlated as follows  

In this equation, S is a dimensionless constant and characterizes the influence of agitator type together with the geometrical situation D/Tand H/T. This equation can be chosen for calculations on small scale, if no special geometries have to be considered. Even when keeping up with these requirements, still deviations from experimental data larger than 20% can occur. 

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