Particle growth and droplet deposition in fluidised bed granulation

The aim of the presented work is the investigation of the growth process in a continuously operated fluidised bed granulator. For that purpose, granulation experiments were performed and system hold-up and particle size distributions were measured. For the interpretation of the results, a model was developed taking into consideration the particle exchange between nozzle jet and fluidised bed as well as the wetting and drying process. In contrast to the commonly found assumption that droplet deposition is analogous to dust deposition in fluidised bed filters, this model was developed to describe the processes in the nozzle region of a submerged nozzle that leads to a system comparable to that of a wet scrubber. Consequently, the growth rate as a result of the droplet deposition is found to increase with particle size.