PARTICLE GROWTH IN A CONTINUOUSLY OPERATED FLUIDIZED BED GRANULATOR

摘要

Fluidized bed spray granulation offers several advantages compared to commonly usedrndrying processes as spray drying, e.g. free flowing dust free coarse particles with arnnarrow particle size distribution can be produced in a single processing step. Especiallyrnfor large production units a continuous operation is desirable. Unfortunately, there isrnstill a lack of understanding concerning the mechanisms of particle formation andrngrowth leading to difficulties in planning and operating such continuous granulators.rnHence, experiments were performed to investigate the influence of process parametersrnon the growth process in a continuously operated fluidized bed granulator. Furthermore,rna model was developed taking into consideration the particle exchange between nozzlernjet and fluidized bed as well as the wetting and drying processes. The processes insidernthe jet are modeled in analogy to a wet scrubber. This modeling approach predicts anrnincrease of growth rate with particle size. The prediction is in good agreement withrnexperimental findings.