CFD-DEM simulations of the gas and particle dynamics in a novel prismatic spouted bed

In this investigation a prismatic spouted bed apparatus with two horizontal gas inlets was modeled by using a Discrete Element Model (DEM) coupled with Computational Fluid Dynamics (CFD), also called Discrete Particle Model (DPM). The bed hydrodynamics were characterized experimentally by means of high speed video recordings and Fast Fourier Transformation (FFT) of the measured pressure drop signal. Different operational regimes could be identified by the FFT. The simulations were performed at the gas flow rates corresponding to the minimum spouting velocity ums, to the upper end of the dense spouting domain and to the instable region at high gas velocities. The simulations predict well the expansion of the particle bed, the particle flow patterns, and characteristic pressure drop fluctuations for all studied regimes. Single peaks in the FFT power plots, characteristic to the stable dense spouting, were obtained and are in good agreement with experiments regarding the frequency of the pressure fluctuations. The irregular pressure behaviour resulting in additional peaks in the FFT spectra was predicted accurately by the DPM model. The spouted bed was characterized regarding the particle micromechanics in the apparatus regions with different particle dynamics, such as the annulus, fountain and spout.