Analysis of powder motion in a packed bed of blast furnace using the discrete element method

Owing to powder accumulation in the packed bed, the permeability of gas and liquid deteriorates, which decrease throughput of the blast furnace. Powder in the moving bed has a large effect on the productivity and efficiency of the blast furnace process when operating with low coke rate and using high-reactivity coke. Therefore, an investigation on the effect of the powder's physical properties and the moving bed material on transport phenomena and the accumulation mechanism of powder in the blast furnace is essential. In the present study, the motion of powder particles was simulated using the discrete element method (DEM), and the effect of the powder particles' shape on the behavior and accumulation of powder was investigated. The study used DEM to reproduce the movement of particles by solving the equations of motion of individual particles. Since the particles were treated as spherical objects in DEM, contact friction and rolling resistance were implemented to represent the irregular shape of actual powder particles. The calculation results showed that contact friction and rotational resistance affected the static holdup of the powder. The amount of clogging of powder at a bottleneck in the moving bed increased with increasing coefficients of friction and resistance. Moreover, the impact of the flow velocity of the gaseous phase on the accumulation behavior of powder was examined. The frictional force on powder particles at the bottleneck increased with an increase in the gas velocity. The clogging of powder occurred easily as a result.