传统与聚合射流氧枪冲击炼钢熔池效果的数值模拟

通过90 t转炉的传统氧枪喷孔周围增加环氧孔,通人辅助氧气保护主氧射流形成聚合状态,建立二维两相数值模型,分析传统氧枪和聚合射流氧枪射流轴线上氧气射流速度分布及不同枪位下熔池中钢液的流动特性和冲击深度。结果表明,与传统氧枪相比,枪位相同时,聚合射流氧枪射流衰减慢,冲击力大,冲击凹坑深度深;在30De(De-氧枪出口直径)枪位下的最大冲击深度与20De枪位下的传统氧枪相同,当聚合射流氧枪在40De枪位下喷吹得平均冲击深度与传统氧枪20De枪位喷吹时相当。     

聚合射流流场的仿真模拟

 为研究有低密度伴随的聚合射流氧枪射流流场,利用氧枪射流检测系统,对常温下(冷态)以空气模拟的射流进行了物理模拟。结合数值模拟结果,分析了传统无伴随流射流以及带有副孔氦气低密度伴随情况下射流流场的流动状态,讨论了在不同的滞止压力和环境温度时有、无伴随射流流场特性。结果表明,修正的k ε双方程模型能较好地预测实验结果,伴随流的存在减缓了中心射流的沿程衰减,环境温度的变化影响射流在径向和轴向的流动状态。     

炼钢氧枪的集束射流数值模拟研究

利用Fluent软件对炼钢氧枪射流流场的速度进行了模拟,发现集束氧枪较超音速氧枪气流沿中心轴线的速度衰减显著下降。对集束氧枪流场的温度和密度进行模拟,采用燃气燃烧产生的高温的、低密度保护区域是集束氧枪核心段延长的主要原因;而采用纯氧作为保护气不能增加主射流核心段长度,因此纯氧方案作为保护气是不可行的。研究为炼钢用氧的集束射流设计提供了理论依据。     

环氧温度对超音速主射流特性的影响

超音速氧气射流喷吹工艺是炼钢过程的重要技术,通过在主氧周围增加环状高温伴随流是改善主氧射流特性、提高冶炼效率的重要途径。通过数值模拟的方法研究集束射流条件下环氧温度对超音速氧气射流特性的影响。研究结果表明,高温环氧可抑制超音速主射流速度的衰减,环氧温度越高,速度衰减越慢,射流核心区长度明显延长;不同环氧温度下,主射流温度均呈现先增大后减小的趋势,环氧温度的升高使得主射流温度的快速增长受到抑制;环氧在主射流周围形成高温低密度区域,将主射流与环境介质隔离,延缓主射流与周围介质的掺混,对主射流起到封套作用。     

聚合射流氧枪射流特性的数值模拟及应用

利用Fluent软件对电炉炼钢中两种常用氧枪,聚合射流氧枪和普通超音速氧枪进行了射流特性的数值模拟,分析了保护气位置、射流角度及压强对聚合射流氧枪射流特性的影响,并在天津钢铁集团公司110t电炉进行了生产实践。结果表明,使用聚合射流氧枪后电炉冶炼效果改善,平均冶炼周期缩短10～15min,各项消耗指标改善。     

120 t转炉旋流氧枪的射流搅拌特性

 熔池流动状态及反应速度是实现转炉高效冶炼的关键,主要取决于氧气射流与熔池的相互作用及底吹搅拌强度。建立了120 t转炉旋流氧枪的三维全尺寸几何模型,利用数值模拟研究了不同旋流角旋流氧枪的射流特性,并对比分析了其对转炉熔池的冲击搅拌效果。结果表明,随着旋流角的增大,氧气流股的射流核心区长度不断减小,射流中心距氧枪轴线距离增大,氧枪射流交汇点距喷孔出口距离不断增大,射流聚合现象被抑制;当旋流角由0°增加至15°时,氧气射流的冲击深度减小了40%,冲击半径增加了13%;熔池纵截面上的高速区域分布在冲击凹坑附近,横截面上的高速区域分布在冲击凹坑及相邻凹坑连接处延长线外部区域。     

超音速氧枪射流特性的数值模拟

利用GAMBIT建立了轴向计算长度2 200 mm和径向计算长度800 mm的超音速氧枪的数学模型,并采用FLUENT软件对氧枪射流特性进行数值仿真研究。分析了单孔氧枪超音速射流特性,以及操作压力(0.6~1.0 MPa)和环境温度(298~1 873 K)对流动特性的影响。结果表明,入口滞止压力在设计压力±25%内对射流轴向衰减及径向扩展影响不大,其与射流的超音速区长度呈二次曲线关系变化,随环境温度升高,射流轴向衰减变缓慢,核心区长度增加,超音速区长度和环境温度呈线性关系,环境温度对射流径向影响很小。     

200 t转炉交错氧枪设计优化研究

以200t转炉5孔氧枪为原型,优化设计内外喷孔相同倾斜角度下不同流量配比的交错氧枪.基于射流特性仿真研究,通过数值模拟方法,分析交错氧枪喷头射流特性与传统5孔氧枪的不同,探讨内外孔流量比变化对氧枪射流轴向速度衰减和有效冲击面积的影响规律.结果 表明:交错氧枪内孔射流轴向速度大于传统氧枪,外孔的轴向速度与传统氧枪相近,但...     

150t转炉五孔氧枪射流特性数值模拟研究

以某钢厂150 t转炉为研究对象,建立了三维数学模型,利用数值模拟方法研究了不同喷孔倾角、喉口直径以及马赫数对五孔氧枪射流特性的影响规律。结果表明：随五孔氧枪喷孔倾角的增加,射流核心段轴向长度减小,氧枪头下方负压区增大,射流向下偏移量减小,到达冶炼枪位时射流速度减小且射流面积增大;随五孔氧枪喉口直径的增大,射流核心段轴向长度增大,到达冶炼枪位时射流速度、射流面积均增大,冶炼枪位时喉口直径41.1 mm的射流速度分别是喉口直径39.9、38.7、37.5 mm的1.01、1.05、1.07倍;随五孔氧枪马赫数的增加,射流核心段轴向长度略微增加,到达冶炼枪位时射流面积稍有减小,但均变化不大。     

120 t转炉用双马赫数氧枪喷头射流特性研究

针对转炉吹炼过程中传统氧枪寿命短、喷溅黏枪烧枪、吹炼时间长等问题,设计了一款双马赫数氧枪,在传统氧枪喷头上增设中心孔。利用数值仿真建立数学模型,分析不同马赫数的超音速射流特性。结果表明,设计的3种方案中,当中心孔马赫数为1.98、外围孔马赫数为2.08时,可以获得更好的吹炼效果。双马赫数氧枪较传统氧枪在有效冲击面积上更具优势,中心孔可以抵消传统周边5孔布置引起的枪下负压区,从而减少黏枪概率,双马赫数氧枪在提高喷头寿命和增强吹炼的稳定性方面具有优势。     

Effect of shrouding Mach number and ambient temperature on the flow field of coherent jet with shrouding Laval nozzle structure

The coherent jet technology was widely used to improve the stirring effect of molten bath in steelmaking field, and the key to this technology was to form a low-density zone around the main oxygen jet by a high-temperature shrouding flame. With this revelation, a shrouding nozzle was processed to a Laval nozzle structure fitted with a loop arrangement for increasing the velocity of shrouding jet. For further increasing the area of the low-density zone, the preheating method was also adopted in this new coherent lance structure. In this paper, the effect of Mach number of the shrouding nozzle on the flow field of the coherent jet was investigated at room and high ambient temperature using numerical simulation and experimental studies. The result represented the simulation model used in this research showed good agreement with the experimental data at the texted conditions. Although the shock wave formed by the shrouding jet removed more kinetic energy form the main oxygen jet, the impaction ability of the coherent jet was much bigger than that of conventional supersonic jet, and this phenomenon would be further strengthen if ambient temperature and Mach number of the shrouding nozzle increases.     

180 t转炉超音速射流和聚合射流与炼钢熔池作用的水模型实验研究

以鞍钢180 t顶底复吹转炉为原型,设计超音速氧枪喷头进行了复吹转炉传统射流与聚合射流对熔池相互作用的水力学模型实验。超音速射流水模实验确定最佳的均混时间为12.6 s;在保持最佳顶吹气体流量的条件下,以降低枪位模拟聚合射流对熔池的相互作用。结果表明:当氧枪枪位下降到40 mm时,均混时间为11.8 s,这说明聚合射流完全可以达到传统射流对熔池的搅拌效果,可取消底吹系统,简化转炉设备和提高转炉炉龄。     

70 t 电弧炉炼钢集束射流氧枪流场的数值模拟及应用

用CFX5.7.1 软件对电弧炉炼钢用集束射流氧枪和普通氧枪的射流特征进行了数值模拟和冷态试验。结果表明,集束射流氧枪比普通超音速氧枪射流长,射流集中、衰减慢。在鄂钢70 t Consteel电弧炉 上应用表明,使用集束氧枪后平均电耗由338 kWh/t降低到219 kWh/t,电极消耗未变,为1.86 kg/t,氧耗由 51.6 m³/t提高到60.3 m³/t。     

Effect of methane-hydrogen mixtures on flow and combustion of coherent jets

Coherent jets are widely used in electric arc furnace(EAF)steelmaking to increase the oxygen utilization and chemical reaction rates.However,the influence of fuel gas combustion on jet behavior is not fully understood yet.The flow and combustion characteristics of a coherent jet were thus investigated at steelmaking temperature using Fluent software,and a detailed chemical kinetic reaction mechanism was used in the combustion reaction model.The axial velocity and total temperature of the supersonic jet were measured via hot state experiments.The simulation results were compared with the experimental data and the empirical jet model proposed by Ito and Muchi and good consistency was obtained.The research results indicated that the potential core length of the coherent jet can be prolonged by optimizing the combustion effect of the fuel gas.Besides,the behavior of the supersonic jet in the subsonic section was also investigated,as it is an important factor for controlling the position of the oxygen lance.The investigation indicated that the attenuation of the coherent jet is more notable than that of the conventional jet in the subsonic section.     

Computational Fluid Dynamics Modeling of Supersonic Coherent Jets for Electric Arc Furnace Steelmaking Process

Supersonic coherent gas jets are now used widely in electric arc furnace steelmaking and many other industrial applications to increase the gas–liquid mixing, reaction rates, and energy efficiency of the process. However, there has been limited research on the basic physics of supersonic coherent jets. In the present study, computational fluid dynamics (CFD) simulation of the supersonic jet with and without a shrouding flame at room ambient temperature was carried out and validated against experimental data. The numerical results show that the potential core length of the supersonic oxygen and nitrogen jet with shrouding flame is more than four times and three times longer, respectively, than that without flame shrouding, which is in good agreement with the experimental data. The spreading rate of the supersonic jet decreased dramatically with the use of the shrouding flame compared with a conventional supersonic jet. The present CFD model was used to investigate the characteristics of the supersonic coherent oxygen jet at steelmaking conditions of around 1700 K (1427 °C). The potential core length of the supersonic coherent oxygen jet at steelmaking conditions was 1.4 times longer than that at room ambient temperature.     

180 t转炉聚合射流流场的水力学模型的实验研究

采用几何相似比1∶10水模型对180 t顶底复吹转炉内射流与熔池相互作用进行模拟试验,研究了在最佳枪位(150 mm)时氧气流量(38~42 m³/h)对均混时间的影响以及最佳顶枪流量(39 m³/h)下聚合射流氧枪枪位(40~150 mm)对均混时间的影响。结果表明,聚合射流氧枪对熔池的搅拌效果完全能达到顶底复吹的搅拌效果,如能在转炉冶炼工艺中应用,可取消底吹系统,简化转炉设备,提高转炉炉龄。