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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