ISSN:
1542-6580
Source:
Berkeley Electronic Press Academic Journals
Topics:
Process Engineering, Biotechnology, Nutrition Technology
Notes:
To further the understanding of fine particle spouting phenomenon that has not been fully experimentally investigated until now, this article discusses some fundamental aspects of the computational fluid dynamics (CFD) simulation of fine particle spouting. Using the two-fluid method (TFM) embedded in the commercial CFD simulation package Fluent (Version 6.1), the spouting hydrodynamics of fine particles in a cylindrical-conical spouted bed is simulated and compared with the experimental data of Chen ["Spouting of fine particles at elevated pressure", (M. A. Thesis), Beijing, University of Petroleum, (1999)]. The results show that for the CFD simulation of fine particle spouting, the Gidaspow ["Multiphase flow and fluidization", Academic Press, San Diego, (1994)] model gives the best predictions of the flow pattern and the minimum spouting velocity; the influence of frictional stress is much more significant than for the CFD simulation of coarse particle spouting; the influences of the coefficient of restitution of particles on the fine particle spouting cannot be neglected, identical with the case of coarse particle spouting. Then, some typical hydrodynamic properties of fine particle spouting are simulated using the related models with suitable parameters. The results reveal that the flow regime transition of fine particle spouting is very similar to that of coarse particle spouting, but fine particle spouting is less stable and is limited to a more restricted region; the McNab ["Prediction of spout diameter", Brit. Chem. Eng. Proc. Tech., 17, 532-541, (1972)] spout diameter correlation derived from experiments of coarse particle spouting is also suitable for fine particle spouting; the denser zone surrounding the spout axis in the spouted bed of fine particles is more obvious than that in the spouted bed of coarse particles; the particles in the spouted bed of fine particles are much quickly accelerated to their maximum velocities than those in a spouted bed of coarse particles. These differences are mainly caused by the aggregating tendency of fine particles.
Type of Medium:
Electronic Resource
URL:
http://www.bepress.com/ijcre/vol4/A27
Permalink
