CFD-DEM modeling for optimized liquid distribution in fluidized bed spray granulation

In this work, CFD-DEM simulations of two different fluidized bed granulator geometries were performed, aiming to provide an insight into how the injected liquid behaves within the particle bed and thus an overall better understanding of the granulation process itself. Simulation results were evaluated regarding the fate of sprayed droplets, e.g. deposition on a particle, elutriation from fluidized bed, or collision with apparatus walls. For the deposited droplets, the particle–droplet collisions were tracked in order to obtain a locally resolved deposition rate. Spray parameters as well as geometric specifications of the nozzle setup were varied, investigating a broad range of different process conditions. By optimizing apparatus design, especially the air inlet, an even distribution of the liquid droplets within the fluidized bed and overall higher deposition rate can be achieved and a stable steady state with a well-defined spray zone is reached within a broad range of varied spray parameters. • A novel fluidized bed granulator geometry was investigated by means of CFD-DEM simulations. • Locally resolved droplet deposition rate as well as droplet fates were analyzed. • Reactor geometry significantly influences liquid distribution. • Detailed information of the deposition can help to detect local overwetting.