Solids flow in dish granulators

In many granulation processes, size enlargement is achieved by the collision of moist particles undergoing a rolling motion. The inclined dish granulator is a suitable device consisting of a shallow cylindrical dish rotating about its cylindrical axis, this being inclined to the horizontal. The classifying effect within the dish often causes the product size distribution to be narrow thereby avoiding downstream screening. Here the effect of the dish and material parameters on the material flow pattern and power requirement are analysed. Dynamic similarity of the material how pattern was demonstrated. This pattern was found to be dependent on a rotational Froude number, the angle of inclination, the dimensionless dish geometry and material properties. The dimensionless power requirement of the dish may also be related to this set of parameters. An analysis of the geometry of the material surface in the dish provided an analytical expression which could be related to experimental phenomena at low Froude numbers. (C) 1997 Elsevier Science Ltd.