Spouted beds have shown great applicability for particles which are difficult to handle in classical fluidized beds, as e.g. very small or big or cohesive ones. This research project is focused on the experimental and numerical investigation of three-dimensional prismatic spouted beds in laboratory and pilot plant scale. The laboratory apparatus ProCell 5 (Glatt, Germany) with different particles is used for coating purposes and the droplet distribution is investigated numerically in order to predict the change of process conditions. CFD-DEM simulations allow the detailed flow description on the scale of single particles as for example the calculation of circulation frequencies, residence times and surface coverage with coating agent. In both experiments and simulations the pressure drop signal is recorded and analyzed by means of Fourier transformation in order to validate the simulations and to quantify the spouting stability.

Besides the experimental part of the project, the spouted bed process is simulated. Therefore, a computational fluid dynamics (CFD) and a discrete element method (DEM) approach are used and combined. For the description of the fluid phase the CFD tool OpenFOAM® is used. The determination of the particle forces and velocities is carried out with LIGGGHTS®. With regard to a feasible simulation time, the simulations are parallelized and a coarse-grain approach is used in order to handle a high amount of particles. Regarding the coating of the granules, a spray zone is implemented and the residence time distribution of the particles in the zone is determined. The liquid injection is performed in a post-processing step after the resource-intensive simulations as the liquid loading during the investigated coating process is very low. A sketch of droplet injection in post-processing step is shown in Fig. 2.