Characterization of fluidized bed layer inversion in a 191-mm-diameter column using both experimental and CPFD approaches
Résumé
A bed containing equal volumes of 1.85 mm glass beads (rho(p)=2500 kg/m(3)) and 0.550 mm ceramic spheres (rho(p)=3800 kg/m(3)), was fluidized by water in a 191 mm i.d. cylindrical column. The water velocity was varied from 16.5 to 52.5 mm/s to investigate the phenomenon of layer inversion at three temperatures (5, 10 and 20 degrees C). The inversion velocity was found to decrease by 7% on reducing the temperature from 20 to 10 degrees C, with no further decrease at 5 degrees C. The operating temperature had an important effect on the degree of separation between the two solids. In contrast to what has been reported for columns of smaller diameter, gross circulation was found to play an important role in enhancing particle mixing. Quantitative and qualitative predictions of layer inversion and binary component segregation at different liquid velocities and of chaotic circulation patterns were carried out by Eulerian-Lagrangian Computational Particle-Fluid Dynamics (CPFD) modelling, using Barracuda software. The predictions are in reasonable agreement with the experimental observations. (C) 2012 Elsevier Ltd. All rights reserved.