A First Approach to CFD Simulation of Hydrodynamic Behaviour in a Conical Spouted Bed Contactor

摘要

Spouted beds have a widespread application in the processing industry for efficientncontacting of large particles with a gas. However, there is no detailed understandingnof the complex behaviour of these systems, especially for fine particles,nwhich means significant scale-up problems in industry. This paper approachesnfundamental aspects of the computational fluid dynamic simulation of fine particlenspouting. Using the commercial CFD simulation package Fluent (version 6.3),nthe spouting hydrodynamics of fine particles in a conical spouted bed is simulatednand compared with experimental data.nFluent code offers a variety of models to describe the physical phenomena occurringnin these kinds of reactors. In some cases, the choice is straightforward,nwhereas in other cases more than one option is valid a priori, and so the best onenhas to be selected. The main choices are the Lun et al. (1984) approach for granularnkinetics and the Gidaspow model for drag force.nIn order to validate this selection process, model predictions are compared withnexperimentally observed hydrodynamic patterns, whereby CFD model parametersncan be tuned. It has been proven that after this tuning, the model explainsnthe hydrodynamic behaviour of the bed and the influence of geometric parametersnand bed nature (sand, glass beads) concerning spout stability and minimumnspouting velocity. Nevertheless, peak pressure drop values predicted by the modelnare considerably smaller than the experimental values. The model also provides reasonable predictions for spout shape, local bed voidage and air and particle velocities.