Numerical Investigation of the Inner Profiles of Ironmaking Blast Furnaces: Effect of Throat-to-Belly Diameter Ratio

The inner profile of iron making blast furnace (BF) is of significant importance to reactor performance. However, its determination lacks any sound theoretical and empirical base. This paper presents a numerical study of the multiphase flow and thermochemical behaviors inside BFs with different inner profiles by a multi-fluid process model. The validity of the model is first confirmed by various applications. It is then used to study the effect of throat-to-belly diameter ratio (R_D) with respect to productivity, burden distribution pattern, and softening-melting temperature of ferrous materials. The results show that when R_D increases, the fuel rate increases at relatively low productivities; however, it initially decreases to a minimum and then increases at relatively high productivities. This performance against R_D to some degree varies with either burden distribution pattern or softening-melting temperature of ferrous materials. Optimum R_D can be identified with relatively small coke rate and minimum fluctuations of global performance and in-furnace states. The analysis of the in-furnace states reveals that the flow and thermochemical behaviors above the cohesive zone are drastically deteriorated with increasing productivity for BFs with relatively small R_D, leading to different variation trends of fuel rate.