Effect of vortex orifice air distributor on granule growth in conical fluidized bed granulation with bottom entry spray

This investigation is undertaken to obtain information on the effect of vor tex orifice air distributors on the granule growth in conical fluidized bed granulation with a bottom entry spray. The five types of vortex orifice di stributors suitable for a strong swirling air supply at the base of the con ical bed were prepared. Although all these orifices consisted of four tange ntial injection nozzles with the same opening, the opening size of the air injection nozzle in each of the orifices was different. Intensity of the ai r injection nozzle torque within the vortex orifice was measured by a torqu e balance method. The granule formation of fluidizing lactose particles in the process of size-enlargement was carried out by spraying an aqueous HPC solution into the bed where the moisture content of granules was maintained at or below 0.30 wt%. As a result, granule growth in the bed could be prec isely controlled by changes in the air injection nozzle torques arising fro m the vortex orifice distributor. The extent of granule growth, namely the granule growth conversion increasing with accumulated content of HPC in the bed particles during the operating time decreased according to the air inj ection nozzle torque within the vortex orifice. Using these process variabl es, granule growth conversion could be arranged experimentally. It is final ly found that one of the features of the proposed air distributor is useful for size-control of granule products in the conical fluidized bed granulat ion with a bottom entry spray.