Changes of blowing characteristics for worn supersonic oxygen lance nozzle in converter
LÜ Ming1, CHEN Shuang-ping1, LI Hang1, ZHANG Zhao-hui1, LI Tao2, LIU Kun-long1
1. School of Metallurgical Engineering, Xi′an University of Architecture and Technology, Xi′an 710055, Shaanxi, China; 2. Hanzhong Iron and Steel Co., Ltd., Shaanxi Steel Group, Hanzhong 724200, Shaanxi, China
Abstract:The oxygen lance nozzle of converter will be eroded to different degrees with the increase of lance age. In order to investigate the influence of oxygen lance erosion degree on the supersonic gas jet blowing characteristics, a three-dimensional full-size geometric model of 120 t converter and a supersonic oxygen lance were established, and the effects of different wear angles for oxygen lance nozzle on the gas jet characteristics, molten bath velocity, and wall erosion were studied. It is found that with the increase of wear angle, the jet velocity decays faster, the length of jet core area and the same isovelocity line are shortened, the maximum velocity of jet center and the distance from the maximum velocity point to the center increase. Dynamic pressure decay rate increases with increasing wear angles, the wear angle increases from 0 to 20°, the maximum dynamic pressure at 1.5 m from lance tip is reduced by 14.84%, and the 14 000 Pa isobaric envelope area is reduced from 0.038 m2 to 0.002 m2. The area of high-velocity zone at the liquid steel surface decreases with increasing wear angles, while the area of dead zone increases with increasing wear angle. The high-velocity area of longitudinal section for molten bath is mainly distributed near the impact dent and bottom blowing element, the low-velocity area is mainly distributed at the bottom of molten bath, and the dead zone is mainly distributed in the center of molten bath bottom and the lower part of furnace wall. In the depth range of 0.6 m below molten steel surface, the top blown oxygen jet plays a major role in the stirring of molten bath, the stirring ability of molten bath becomes weaker with the increase of wear angle, and the area of high-velocity zone decreases, while the area of low-velocity zone and dead zone increases. When the depth of molten bath exceeds 0.6 m, the bottom blowing airflow plays a major role in the stirring of molten bath, and the area of high-velocity zone is basically unchanged. The shear stress is concentrated in the slag-metal interaction area, the connection between furnace wall and bottom, and the wall near the bottom blowing stream, thus the erosion of refractories is serious. The turbulent kinetic energy and shear stress of fluid near the molten bath wall decrease with the increase of wear angle, and the erosion velocity of converter lining decreases.
[1] LI Qiang,LI Ming-ming,KUANG Shi-bo, et al. Numerical simulation of the interaction between supersonic oxygen jets and molten slag-metal bath in steelmaking BOF process[J]. Metallurgical and Materials Transactions B-Process Metallurgy and Materials Processing Science, 2015, 46(3): 1494. [2] 刘浏, 余志祥, 萧忠敏. 转炉炼钢技术的发展与展望[J]. 中国冶金, 2001,5(1): 20. (LIU Liu, YU Zhi-xiang, XIAO Zhong-min. Development and prospects of converter steelmaking technology[J]. China Metallurgy, 2001,5(1): 20.) [3] 杨利彬, 曾加庆, 邓勇, 等. 大型转炉高效率、长寿命顶底复合吹炼技术[J]. 钢铁, 2020,55(4): 45. (YANG Li-bin, ZENG Jia-qing, DENG Yong, et al. Highly efficiency and long-life combi ned blowing technology of big converter[J]. Iron and Steel, 2020,55(4): 45.) [4] 杨文远, 郑丛杰, 王明林, 等. 转炉高效吹炼技术的研究[J]. 钢铁, 2001,36(11): 13. (YANG Wen-yuan, ZHENG Cong-jie, WANG Ming-lin, et al. Study on high-efficiency blowing technology on converter[J]. Iron and Steel, 2001,36(11):13.) [5] 蒋晓放, 杨文远, 吴亚明, 等. 大型转炉双角度氧枪喷头高供氧强度炼钢[J]. 钢铁, 2021,56(9): 62. (JIANG Xiao-fang, YANG Wen-yuan, WU Ya-ming, et al. High oxygen supply intensity steelmaking with dual-angle oxygen lance nozzle in large converter[J]. Iron and Steel, 2021,56(9):62.) [6] 郑颖, 蒋宏, 周虹, 等. 80 t顶底复合吹炼转炉的冶金效果[J]. 钢铁研究学报, 2001,13(5): 11. (ZHENG Ying, JIANG Hong, ZHOU Hong, et al. Metallurgical effect of 80 t combined blowing oxygen converter[J]. Journal of Iron and Steel Research, 2001,13(5): 11.) [7] 赵冲, 陈威, 张立峰. 转炉顶吹过程多相流数值模拟[J]. 中国冶金, 2018,28(增刊1): 1. (ZHAO Chong, CHEN Wei, ZHANG Li-feng. Numerical simulation of multiphase flow in converter top blowing process[J]. China Metallurgy, 2018,28(s1): 1.) [8] 于小方, 杨文远, 郑丛杰. 提高转炉的供氧强度[J]. 钢铁研究学报, 2000, 12(2): 6. (YU Xiao-fang, YANG Wen-yuan, ZHENG Cong-jie. Study on increasing the intensity of supplying oxygen in converter[J]. Journal of Iron and Steel Research, 2000,12(2): 6.) [9] LI Ming-ming, LI Lin, LI Qiang, et al. Effect of ambient temperature on characteristics of jets from oxygen lance in BOF steelmaking[J]. Journal of Northeastern University(Natural Science), 2014, 35(10): 1437. [10] 胡绍岩, 朱荣, 董凯. 炼钢温度下复吹转炉流场的数值模拟研究[J]. 工程科学学报, 2018, 40(增刊1): 108. (HU Shao-yan, ZHU Rong, DONG Kai. Numerical simulation study of the flow field in a re-blowing converter at steelmaking temperature[J]. Chinese Journal of Engineering, 2018, 40(s1): 108.) [11] 吕明, 庞焯刚, 李小明, 等. 转炉顶吹气体射流的冲击特性[J]. 钢铁, 2019, 54(7): 35. (LÜ Ming, PANG Zhuo-gang, LI Xiao-ming, et al. Impact characteristics of the top blowing gas jet in the converter[J]. Iron and Steel, 2019, 54(7):35.) [12] 陈圣桢, 朱荣, 冯超, 等. 预热温度对于混合喷吹O2+CO2旋流氧枪喷头射流特性的影响[J]. 工业加热, 2022, 51(2): 6. (CHEN Sheng-zhen, ZHU Rong, FENG Chao, et al. Effect of preheating temperature on jet characteristics of mixed O2+CO2 swirl nozzle[J]. Industrial Heating, 2022, 51(2): 6.) [13] FENG Chao, CHEN Sheng-zhen, DONG Jian-feng, et al. Influence of preheating temperature on the characteristics of O2 + CO2 jet by mixed injection with a swirling oxygen nozzle[J]. JOM, 2021, 73(10):2985. [14] LI Jian-chao,LU Qing,LIU Xiao-jie,et al.Phosphorus capacity of CaO-SiO2-Al2O3-MgO-FexO slag[J]. Journal of Iron and Steel Research, International, 2015, 22(5): 377. [15] 吕明, 李航, 谢堃. 120t转炉旋流氧枪的射流搅拌特性[J]. 钢铁, 2021, 56(4): 31. (LÜ Ming, LI Hang, XIE Kun. Jet stirring characteristics of nozzle twisted lance in 120 t converter[J]. Iron and Steel, 2021, 56(4): 31.) [16] 吕明, 魏鑫燕, 朱荣, 等. 旋流氧枪在提钒转炉上的应用[J].钢铁,2012,47(6):37. (LÜ Ming, WEI Xin-yan, ZHU Rong, et al. Application of swirl-type oxygen lance in vanadium extraction converter[J]. Iron and Steel, 2012, 47(6):37.) [17] 李琳, 李明明, 李强, 等. 漩流氧枪转炉炼钢熔体的喷溅行为[J]. 钢铁, 2020,55(6): 54. (LI Lin, LI Ming-ming, LI Qiang, et al. Melt splashing behavior of steelmaking converter with nozzle-twisted lance[J]. Iron and Steel, 2020, 55(6): 54.) [18] Garajau F S, Guerra M D L, Maia B T, et al. Effects of post combustion temperature on the wear of the supersonic nozzles in BOF lance tip[J]. Engineering Failure Analysis, 2019, 96(9): 175. [19] FENG Chao, ZHU Rong, HAN Bao-chen, et al. Effect of nozzle exit wear on the fluid flow characteristics of supersonic oxygen lance[J]. Metallurgical and Materials Transactions B—Process Metallurgy and Materials Processing Science, 2020, 51(1): 187.