Optimized combustion characteristics in a top-blown converter utilizing a swirling-flow post-combustion oxygen lance

Abstract

The steel industry is confronted with urgent challenges in the Post-Combustion (PC) phase of converters, such as reduced combustion efficiency, inefficient energy utilization, and high CO emissions. To address these issues, this study presents an innovative technical approach: integrating secondary combustion with swirl composite injection smelting. By leveraging the Swirl-Flow Post-Combustion Oxygen Lance (SFPCL), a comprehensive three-dimensional numerical model of the combustion zone in a top-blown converter has been developed. Using Computational Fluid Dynamics (CFD) techniques combined with a turbulence-chemical reaction coupling model, this study investigates the velocity field, temperature field, component distribution, and Post-Combustion Ratio (PCR) related to the SFPCL. The results indicate that the swirling jet ejected from the primary oxygen nozzle significantly enhances the jet's independent characteristics and effectively reduces the coupling between the primary and secondary jets. The secondary jet's impact area increases, and its impact velocity at H = 1.25 m rises by 39.12 %. As the swirl angle was incremented to 15°, the CO concentration within the converter space diminished by 37.5 %, whereas the CO₂ concentration escalated by 42.86 %. Furthermore, the combustion temperature soared by 215K, and the combustion zone area expanded by 36.67 %. At the converter outlet, notable changes were observed: the CO concentration decreased by 2.56 %, the CO₂ concentration rose by 2.7 %, and the PCR improved by 3.7 %. These findings underscore that increasing the swirl angle can bolster post-combustion efficiency and mitigate CO emissions. This study offers fresh theoretical underpinnings and practical insights for developing high-efficiency, energy-saving converter steelmaking technologies.