Computational Study of Gas-Flow and Temperature Dynamics at Blast Furnace Charging

The burden in the blast furnace is charged to form separate layers of ore and coke, which makes it possible to control the conditions in the shaft because the materials have different gas permeabilities and therefore affect the gas distribution in the shaft. Since ore and coke are of fundamentally different densities, the burden mass flux at different radial locations will vary, which influences the heating of the burden upon its descent. To gain an understanding of the effect of charging on the thermal and flow conditions in the upper shaft, the system is analyzed by computational fluid dynamics combined with the discrete element method. A model of the counter-current flow of gas and solids and the temperature of the two phases in a simplified setup is developed. It simulates the intermittent charging and continuous descent of burden and the simultaneous ascent of gas through the particle bed. The model captures the complex interaction between the solid and gas flows, which affects the radial temperature distribution due to heat transfer and gas redistribution. The dynamics of the system are illustrated and analyzed using a simple charging cycle, and some implications of the findings are discussed.