Holdup and Residence Time Distributions in Inclined Dishes

Inclined rotating dishes are commonly used for particle processing, but the flow behavior of the bed has received little attention. Experiments using nongranulating solids showed that the fractional volumetric holdup was related to the material flow pattern, being dependent upon the rotational Froude number, the dish aspect ratio (rim height/diameter), and the angle of dish inclination. A magnetic tracer method was used to determine the particle exit age distributions. For a monosized feed, the dimensionless variance of the exit age distribution and the rotational Froude number were linearly related and independent of the dish diameter. For two-component feeds, the exit age distributions of the components were not the same and considerable differences were found when one component was present in a small proportion. If the components were of equal proportions, there was a marked and fairly consistent extent of segregation, whatever the operating conditions.