Flow in Granulators
with Ken Ford and Professor Hugo Caram
High shear granulation is used widely in the pharmaceutical industry to blend and agglomerate active and excipient powders. Granulation improves powder flow and compression properties. High shear granulators typically produce flow by sweeping a pitched blade impeller under a granular bed at high rotation rates, providing both fluidization from upward lift and circular flow. We employ a model high shear granulator to investigate the forces produced by the bottom sweeping blades. The forces are partially decoupled by separately vibro-fluidizing (vertical force) and stirring the granular bed with a vane impeller (rotational force). The vane stir power demonstrates a transition between dense granular flow and fluidized granular flow behavior with increased vibration and stir speed. Total power demonstrates a minimum energy input for fluidized granular flow near the transition. The graphs shown represent the vane and total power draw as a function of vane speed and vibration acceleration.
