Abstract: Supersonic jet characteristics of oxygen lance nozzles have a significant influence on smelting. The three-dimensional model of a 250 t steelmaking converter was established by Fluent software. The jet characteristics of a conventional 6-hole oxygen lance with five holes around and one hole in the center and a post combustion (PC) oxygen lance with a single flow channel were compared and analyzed. The interaction between gas-liquid-slag three phases was simulated by VOF multiphase flow model. The results show that the inflow of the left-side secondary hole flow unit quickly converges into the center hole jet, which has a larger radial cross-sectional area; while the right-side secondary hole flow unit converges into the peripheral 5-hole main flow unit. Due to the supplement of the second hole flow unit, the velocity under the oxygen lance is evenly distributed, and the low-velocity area is reduced, slowing down the decay of the center hole jet, resulting in a large center hole jet velocity. Therefore, the post combustion oxygen lance has a larger impact area and impact depth. Therefore, it can efficiently decarbonize and phosphoresce, giving full play to the secondary combustion effect, and is conducive to slagging. Through the three-phase simulation study of gas-liquid-slag, it can be seen that the cavity profile and interface of steel-slag-gas remain unstable due to the propagation of surface waves, and the slag layer at the furnace wall is calmer with time, indicating that there is no scouring of the furnace wall by either the conventional oxygen lance or the secondary combustion oxygen lance. The maximum impact diameter and impact depth of the secondary combustion oxygen lance is 2461 mm and 358 mm, which are 1.16 times and 1.19 times than the conventional oxygen lance, respectively. The industrial tests have shown that the use of secondary combustion oxygen lances increases the furnace temperature and significantly reduces the oxygen supply time, while the post combustion oxygen lance increases the converter temperature by 27.2°C, and shortens the oxygen supply time by 78 s.

Key words: converter, single-channel, post combustion oxygen lance, jet characteristics, multiphase flow, numerical simulation, industrial test

摘要： 氧枪喷嘴的超音速射流特性对熔炼有重要影响。本工作结合某钢厂250 t转炉实际，运用Fluent软件建立三维模型，对比分析了周边5孔加中心单孔的普通氧枪与单流道二次燃烧氧枪的射流特性，通过VOF多相流模型对气-液-渣三相之间相互作用进行模拟研究，并开展了工业试验研究。结果表明，相比于普通氧枪，因一侧副孔流股快速汇入中心孔射流而使二次燃烧氧枪有更大的径向横截面积，且其中心孔射流速度大，故二次燃烧氧枪具有更大的冲击面积和冲击深度。通过气-液-渣三相模拟研究可知，由于表面波的传播，钢-渣-气的空腔剖面和界面保持不稳定，且随着时间的推移，炉壁处的渣层较为平静，表明无论是普通氧枪还是二次燃烧氧枪，都不存在冲刷炉壁现象。其中二次燃烧氧枪最大冲击直径和冲击深度为2461和358 mm，分别是普通氧枪的1.16倍和1.19倍。工业试验表明，与普通氧枪相比，二次燃烧氧枪可以提高熔池温度27.2℃，使供氧时间缩短78 s。

关键词: 转炉, 单流道, 二次燃烧氧枪, 射流特性, 多相流, 数值模拟, 工业试验