(664d) A Combined Experimental and Computational Study of Flow Regimes in a Spout-Fluid Bed

Spout-fluid beds find a widespread application in the process industry for efficient contacting of large particles with a gas. However, detailed understanding of the complex behavior of these systems is lacking, which leads to significant scale-up problems in industry. In this contribution we report results of a combined experimental and simulation study on the various regimes, which can be encountered during spout-fluid bed operation.

A regime map for a 3D spout-fluid bed was composed employing spectral analysis of pressure drop fluctuations and fast video recordings. In addition 3D Euler-Lagrange computations were performed to assess the capability of the model to reproduce the experimentally observed flow regimes. The influence of the drag closure on the model results was assessed and the influence of the computational grid was studied using a new method for the implementation of the two-way coupling.

For most regimes our model is able to predict the appropriate regime. The frequency, at which the largest power is found, is overpredicted by the model. Contrary to the experimental observations, our model did not predict any large slugs in the slugging bed regime. The remaining differences between the simulated and experimentally observed bed behavior is most likely related to the representation of the effective fluid-particle interaction in our model, which relies on local spatial homogeneity. Finally, the potential of Direct Numerical Simulation (DNS) to overcome this (remaining) problem will be addressed.