Variation in Flow Characteristics of Molten Baths at Different Blowing Stages in the Converter

Abstract

The metallurgical tasks at different stages of converter blowing are different. The process operation and physical properties of molten baths are also different. It is very important to determine the flow characteristics of molten baths at different blowing stages for optimizing process operation. In this paper, a three-dimensional, full-scale model of a 120 t top–bottom combined blowing converter is established. Based on the parameters of oxygen lance position, bath temperature, bottom blowing intensity, and bath physical properties at different blowing stages, the changes in bath flow field, turbulent kinetic energy, impact depth, impact area, and wall shear force with blowing process are studied. The results show that at the initial stage of blowing, the lance position is high, the impact depth of the molten bath is 0.23 m, the impact area is 5.06 m2, the dead zone area of the longitudinal section is 0.40 m2, and the high-speed zone area is 2.73 m2. As the blowing time increases, the lance position decreases, the impact depth of the molten bath increases, the impact area decreases, and the internal velocity of the molten bath increases. In the later stage of tuyere blowing, the lance level decreases to its lowest, the impact depth increases to 0.42 m, the impact area decreases to 2.83 m2, the dead zone area of longitudinal section decreases to 0.18 m2, and the high-speed area increases to 3.34 m2. The area with the highest wall shear stress is situated within the gas–slag–metal three-phase region, where the lining experiences the most significant erosion. The fluctuation in the slag–metal interface is small, and the wall shear force is 2.80 Pa at the initial stage of blowing. From the early to late stages of blowing, the lance position decreases, the fluctuation range of the slag–metal interface increases, and the erosion of the furnace lining increases. In the later stage of blowing, the maximum wall shear force is 3.81 Pa.

Keywords

• converter steelmaking
• supersonic jet
• molten bath flow
• multiphase flow
• numerical simulation