Particle growth in a continuously operated fluidized bed granulator

Fluidized bed spray granulation offers several advantages compared to commo nly used drying processes as spray drying, e.g. free flowing dust free coar se particles with a narrow particle size distribution can be produced in a single processing step. Especially for large production units a continuous operation is desirable. Unfortunately, there is still a lack of understandi ng concerning the mechanisms of particle formation and growth leading to di fficulties in planning and operating such continuous granulators. Hence, ex periments were performed to investigate the influence of process parameters on the growth process in a continuously operated fluidized bed granulator. Furthermore, a model was developed taking into consideration the particle exchange between nozzle jet and fluidized bed as well as the wetting and dr ying processes. The processes inside the jet are modeled in analogy to a we t scrubber. This modeling approach predicts an increase of growth rate with particle size. The prediction is in good agreement with experimental findi ngs.