Numerical study of post-combustion characteristic in a smelting reduction furnace

For a smelting reduction furnace, the main role of the post-combustion operation in the upper space is to supply the energy required by the endothermic reduction reaction of iron oxide occurring in the melt bath, and thus the post-combustion behavior is important in the respect of reducing the coal consumption. In this paper, based on a developed 3D model composed of the Realizable k-epsilon model and DO radiation model, the post-combustion characteristics in a smelting reduction furnace was studied by numerical simulation, and the effects of top lance height, top-blown hot air flowrate and nozzle inclination angle of top lance on the flow and temperature fields, CO content distribution in the upper space were investigated. The results show that with the increase of top lance height, the length and temperature of combustion flame in the upper space increase, which is beneficial to expanding the post-combustion zone and improving the post-combustion of CO gas. And as the top-blown hot air flowrate increases, the position of the maximum temperature in the upper space gradually moves down and the CO content in gas mixtures decreases, which is conducive to the heat transport back to the melt bath. In addition, a proper velocity and temperature distribution in the upper space and distribution of CO content is obtained under the nozzle inclination angle range from 10 degrees to 15 degrees, but a larger nozzle inclination angle reduces the velocity and temperature in the central zone.