Impact of bottom-blowing parameters on melt pool homogenization in a 120-ton converter based on carbon-oxygen reaction

Abstract

This paper studies a 120 t converter, focusing on the influence of the CO bubbles generated by the carbon-oxygen reaction during the decarburization process on the stirring action of the melt pool. It examines the effect of the intensity and arrangement of bottom blowing on the homogenization effect, taking into account the dynamics of CO bubbles generated from the carbon-oxygen reaction. Initially, a macroscopic kinetics model for the generation of CO bubbles during the carbon-oxygen reaction in converter steelmaking is established. Subsequently, a water model simulation device for CO bubble generation from the converter's carbon–oxygen reaction is designed, establishing a 120 t converter water model experimental setup with a similarity ratio of 1:8. The main indicator for evaluating the homogenizing effect of the converter is the mixing time, based on which, experimental schemes are designed. Water model experiments are conducted to study the influence of bottom-blowing flow and nozzle arrangement on the melt pool's stirring flow field under the action of carbon-oxygen reaction. The results show that greater generation intensity of CO bubbles from the carbon-oxygen reaction leads to shorter mixing time in the melt pool; when the angular spread of the bottom-blowing elements is small, the bottom-blowing gas flow is relatively concentrated, facilitating stirring in the melt pool. However, increasing the angular spread of the nozzles to a certain extent leads to the dispersion of bottom-blowing energy, making it difficult to form effective stirring; when the bottom-blowing flow is less than 1.5 Nm3/h, the mixing time of the melt pool decreases with the increase of bottom-blowing flow; when the bottom-blowing flow is greater than 1.5 Nm3/h, the mixing time of the melt pool increases with the increase of bottom-blowing flow. In addition, a series of industrial experiments were carried out, and the research results were applied to the actual production process. By comparing the test results after the optimization scheme with the production data of the original process, it was found that the optimization scheme significantly improved the smelting efficiency and reduced the production cost. These research results not only provide a theoretical basis, but also provide practical guidance for the optimization of converter smelting process.