Validation of the Eulerian simulated dynamic behaviour of gas-solid fluidised beds

In this paper, a Eulerian-Eulerian CFD model for a freely bubbling gas-soli d fluidised bed containing Geldart-B particles is developed for studying it s dynamic characteristics. This CFD model is based on the kinetic theory of granular flow. Van Wachem et al. (1998a) Comput. Chem. Engng 22 (Suppl.), S299-S307 have shown that this model is capable of providing reasonable pre dictions of the time-averaged properties. In this paper, the dynamic charac teristics of the gas-solids behaviour at different superficial gas velociti es, at different column diameters, and at different pressures are evaluated , namely (A) the velocity of pressure and voidage waves through the bed, (B ) the power of the low and high frequencies of the pressure and voidage flu ctuations, (C) the reorientation of the gas-solids flow just above minimum fluidisation and the effect of elevated pressure upon this reorientation, a nd (D) the Kolmogorov entropy. The CFD simulation results for items (A)-(D) are compared with published experimental data and with appropriate correla tions from the literature. A good agreement is found between the Eulerian-E ulerian CFD simulations of bubbling fluidised-bed dynamics, and the data fr om experiments in the literature. This is a strong incentive for the furthe r development of this type of simulation models in fluidised-bed reactor de sign and scale-up. (C) 1999 Elsevier Science Ltd. All rights reserved.