Abstract

Spouted beds have a widespread application in the processing industry for efficient contacting of large particles with a gas. However, there is no detailed understanding of the complex behaviour of these systems, especially for fine particles, which means significant scale-up problems in industry. This paper approaches fundamental aspects of the computational fluid dynamic simulation of fine particle spouting. Using the commercial CFD simulation package Fluent (version 6.3), the spouting hydrodynamics of fine particles in a conical spouted bed is simulated and compared with experimental data.

Fluent code offers a variety of models to describe the physical phenomena occurring in these kinds of reactors. In some cases, the choice is straightforward, whereas in other cases more than one option is valid <em>a priori</em>, and so the best one has to be selected. The main choices are the Lun et al. (1984) approach for granular kinetics and the Gidaspow model for drag force.

In order to validate this selection process, model predictions are compared with experimentally observed hydrodynamic patterns, whereby CFD model parameters can be tuned. It has been proven that after this tuning, the model explains the hydrodynamic behaviour of the bed and the influence of geometric parameters and bed nature (sand, glass beads) concerning spout stability and minimum spouting velocity. Nevertheless, peak pressure drop values predicted by the model are considerably smaller than the experimental values. The model also provides reasonable predictions for spout shape, local bed voidage and air and particle velocities.

Recommended Citation

Díaz, Luis; Álava, Isabel; Makibar, Jon; Fernández, Ruth; Cueva, Fernando; Aguado, Roberto; and Olazar, Martin (2008) "A First Approach to CFD Simulation of Hydrodynamic Behaviour in a Conical Spouted Bed Contactor," International Journal of Chemical Reactor Engineering: Vol. 6: A31.
Available at: http://www.bepress.com/ijcre/vol6/A31