转炉超音速氧枪喷头磨损后的吹炼特性变化

 转炉氧枪喷头会随枪龄的增加发生不同程度的侵蚀,为了探究氧枪喷头侵蚀程度对超音速气体射流吹炼特性的影响,建立了120 t转炉及超音速氧枪的三维全尺寸几何模型,研究了氧枪喷头不同磨损角度对气体射流特性、熔池速度及壁面侵蚀的影响。发现随着磨损角度增加,射流速度衰减加快,射流核心区长度缩短,同一等速线长度缩短,射流中心最大速度和最大速度点距中心距离增大。射流动压衰减速度随磨损角度增加而加快,磨损角度由0增至20°,距喷头端面1.5 m处最大动压减小了14.84%,14 000 Pa等压线包围面积由0.038 m2减小至0.002 m2。钢液面处高速区面积随着磨损角度增加而减小,死区面积随着磨损角度增加而增大。熔池纵截面高速区域主要分布在冲击凹坑和底吹元件附近,低速区域主要分布在熔池底部,死区主要分布在熔池底部中心和炉壁下部区域。当熔池深度小于0.6 m时,顶吹气流对熔池的搅拌起主要作用,磨损角度增加,熔池搅拌能力变弱,熔池横截面高速区面积减小,低速区和死区面积增大;当熔池深度大于0.6 m时,底吹气流对熔池搅拌起主要作用,高速区面积基本不变。渣-金作用区域和底吹流股附近流体湍动能较大、壁面剪切应力较为集中,该部位耐火材料侵蚀严重。熔池壁面附近流体湍动能和壁面剪切力随磨损角度增加而降低,转炉炉衬侵蚀速度减小。

Changes of blowing characteristics for worn supersonic oxygen lance nozzle in converter

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.