Numerical Analysis on Passage and Blockage Behaviors of Fine Particles through an Orifice Consists of Coarse Particles

Stable operation under low reducing agent rate condition of blast furnace is necessary to realize to contribute solution of global warming. Under low reducing agent rate operation, large amount of powder materials like fine coke and unburnt pulverize coal generate in the furnace. It is known that the heavy accumulation of these powders in the packed bed of blast furnace deteriorates the permeability, and cause operation trouble in extreme case. Thus it is important to understand the flow and accumulation behaviors of powder in packed bed. This paper discussed the powder motion in the packed bed through numerical simulation under simplified condition. A simplified packing structure, namely an orifice consisting of three spherical particles that touched each other and were in equilateral triangle arrangement, was picked out from the packed bed. The powder trajectories passing through this orifice were tracked by using the discrete element method. The simulation results showed that only a few powder particles initiated the blockage of the particle orifice. Additionally the effects of mechanical properties of the particles on the passage and the blockage behaviors were also revealed.