Determination of Optimal Bottom Blowing Angle for Improving Mixing Efficiency and Wall Erosion in Steel-Making Converter: Numerical Modeling and Engineering Application

In our previous work (Powder Technol, 2024, 433, 119276), an approach of inclined bottom blowing has been proposed. It was found that this novel mode of bottom blowing helps to improve the flow characteristics and mixing effect of bath in bottom blowing converters. In this work, the possibility of applying this bottom blowing technique in top and bottom combined blowing converters is investigated. An Euler-Euler model is adopted to describe top and bottom blown process in a simplified model of a 260 t converter. The accuracy of the model is validated by comparing the numerical simulation results with the previously published experimental results. Then, according to the similarity theory, the size of an actual converter is downsized and based on the downsized model a series of numerical simulations are carried out. The influence of bottom blowing angle on the flow characteristics, mixing efficiency and converter wall erosion are discussed in detail. Numerical simulation results show that the mixing time first decreases and then increases with the increase of the bottom blowing angle. When the bottom blowing angle is 5~6 deg, the mixing time of molten pool is the shortest because the flow dynamics in the lower part of the bath are effectively improved by using the 6 deg angle for bottom blowing. The wall shear stress is used to characterize the erosion of the converter wall. The study results show that the most severe area of erosion on the converter wall occurs near the liquid surface in the direction of the top jet. The severity of erosion on the converter wall decreases gradually as the bath depth increases. The wall shear stress changes slightly with the angle, which indicates that the novel bottom blowing approach will not aggravate the wall erosion. Combining with the results in this paper and the factory production demand, the actual industrial converter using the 7 deg bottom blowing angle effectively improve the efficiency of smelting.