Development of tapered rotating fluidized bed granulator for increasing yield of granules

•A novel tapered rotating fluidized bed granulator was developed.•Particle entrainment was reduced in the tapered vessel.•Yield of granules was increased significantly in the tapered fluidized bed.•Uniform granules were prepared from a fine cohesive powder without coarse granules.•The tapered vessel is effective for practical use of the rotating fluidized bed.

A rotating fluidized bed granulator is an attractive technique for handling fine cohesive powders. However, significant particle entrainment and following serious loss of granules have been a major hurdle for its practical use. We here proposed a novel tapered rotating fluidized bed granulator in order to reduce the particle entrainment and increase the yield of granules. The tapered rotating fluidized bed consists of a cylindrical vessel with two frustum ends, in which superficial velocity of the fluidization air is less increased toward an air exit at the center of the vessel. Wet granulation of a fine cohesive powder classified into Geldart Group C was conducted by the developed tapered rotating fluidized bed, and its performance as a granulator for handling a fine cohesive powder was evaluated. The results showed that the particle entrainment was decreased by merely modifying the vessel geometry to the tapered geometry, resulting in a significantly increase in the yield of granules. The particle size distribution of the granules showed unimodal distribution, confirming that granules are able to be prepared from a fine cohesive powder without coarse granules.

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