Permeation and blockage of fine particles transported by updraft through a packed bed

Abstract

The fines generated in iron making blast furnace bring about the unsteady or unstable gas/liquid permeability and solid motion. Fundamental experiment was carried out to investigate the inhomogeneous phenomena such as flow channel blockage by fine particles transferred by updraft through a fixed packed bed. The alumina sphere and coke were used for packed bed and fine particles transferred, respectively. Conclusion of this study is as follows. The principal factor controlling a criterion for the blockage is a particle diameter ratio of coke to alumina particle, and fines concentration is not a primary factor. Consideration on a hydraulic equivalent diameter of a regular packing model of spheres is effective to predict the critical diameter ratio and it resulted in good agreement with the experimentally determined. Locally blocked mass, that is, a cluster consisting of coarse alumina particles and fines through which gas is incapable of flowing is dispersed in the bed. The void fraction of packed bed being equivalent to the pressure drop, calculated from Ergun's equation, is considerably small compared with the initial value when the local blockage is in existence. Fraction of the local blockage calculated from the void fraction and static holdup of fines is 15-20% as far as the present experimental condition. © 2011 ISIJ.