旋流氧枪在提钒转炉上的应用

通过水模拟试验,研究了旋流氧枪对熔池的搅拌效果,发现采用10°旋流氧枪喷吹时混匀时间最短,仅为47.6s,因此,对熔池搅拌的效果最佳。在此基础上,采用10°旋流氧枪在现场150t提钒转炉上进行吹炼提钒。研究发现:采用旋流氧枪可保证提钒转炉冶炼过程的正常进行,半钢钒的质量分数比常规氧枪冶炼时降低17.8%,转炉提钒率提高5.1%,钒渣V2O5品位提高0.93%,减少了铁损,为提高提钒转炉钒资源回收率提供了新技术。     

基于环境温度的转炉旋流氧枪射流分析

为探究旋流氧枪自由射流特性,建立了0°、6°、12°和18°旋流氧枪自由射流几何模型,分析了不同旋流氧枪炼钢温度下的旋流特性、射流速度和动压分布。发现与0°旋流氧枪相比,6°、12°和18°旋流氧枪射流速度和动压衰减较快,且旋流角越大,射流衰减越快。而6°旋流氧枪与12°和18°旋流氧枪相比,射流速度和动压衰减较慢,在保证合适冲击深度和冲击面积的同时,使熔池产生一定的旋转运动。基于此,建立了6°旋流氧枪和转炉气-渣-金多相流几何模型,分析了环境温度变化对6°旋流氧枪冲击特性和熔池速度分布的影响,发现环境温度从300 K升高到1 873 K,冲击半径从1.25 m增至1.78 m,而冲击深度仅从0.119 m增至0.132 m。环境温度升高,钢液面处高速区面积增大,死区和低速区面积减小;在熔池较浅处,环境温度升高,熔池死区面积减小,高速区面积增大,以熔池深度0.3 m为例,环境温度从300 K升高到1 873 K,死区面积由0.41 m²减小至0.17 m²,高速区面积由9.35 m²增至9.76 m²     

260 t转炉用五孔旋流氧枪的数值模拟

为克服传统氧枪在转炉炼钢工艺技术中的局限性,利用数值模拟对不同结构的五孔旋流氧枪进行模拟研究,分析了旋流氧枪的倾斜角(13°～15°)、旋流角(0～15°)对射流的衰减、聚并形态和冲击面积的影响。结果表明:与普通氧枪相比,旋流氧枪的射流速度较低,但因存在切向力,对熔池的搅拌能力更强;倾斜角增大会导致射流径向的速度分量增大;旋流氧枪由于旋流角的作用,发生射流聚并的可能性降低;倾斜角对射流的聚并有重要影响,倾斜角减小,射流聚并更加严重并且射流冲击面积会减小;当倾斜角15°并且旋流角为10°时冲击面积最大。     

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。     

高马赫数氧枪枪位对100 t转炉自动炼钢熔池流速的影响

通过采用数值模拟与冷态水模拟相互印证的手段,以北方某钢厂100 t炼钢转炉为原型,建立了四孔拉瓦尔氧枪喷头与转炉炉体的三维模型,模拟研究了高马赫数氧枪枪位变化对熔池内钢液流速的变化状况以及射流的冲击效果的影响。结果表明:随着氧枪枪位从1.7 m提高到2.5 m,对熔池钢液的冲击能力不断减弱,导致冲击深度不断减小。但是,随着枪位的提高,氧气射流对钢液的作用面积却不断增大。高马赫数氧枪位在1.6～2.2 m冲击深度适中,熔池混匀效果最好,此时钢液流速在熔池径向方向上的分布更加均匀,且高速区域占比更大,混匀时间较短,对熔池底部钢液的搅拌效果最好。     

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。     

高供氧压力下高马赫数氧枪数值模拟

  以北方某钢厂100 t转炉为原型，建立顶吹转炉炉内流场的三维数学模型，采用Fluent软件研究了不同高马赫数氧气射流与熔池钢液速度流场分布之间的依赖关系。研究发现，高马赫数氧枪在Ma（马赫数）为2.0～2.3时，曲线平稳，为最佳供氧压力。在提高供氧压力的同时，氧气射流的最大速度、熔池钢液面的冲击直径及冲击深度也随之增加。模拟结果显示，氧气射流在设计工况氧压小于1.0 MPa时，射流之间相互干扰作用最弱；氧气射流在设计工况氧压力大于1.0 MPa后，冲击直径与冲击深度增幅较小。基于上述研究，在实际生产中应用了高马赫数氧枪后，并结合变枪变压操作工艺，可以改善熔池底部钢液流动状况、稳定转炉吹炼过程、控制炉渣喷溅。     

四孔氧枪顶吹转炉的三相流流场数值模拟

采用数值模拟软件Fluent建立了一个瞬态的三维数学模型,对100 t氧气顶吹转炉流场进行数值模拟。通过改变氧枪枪位和氧枪喷孔夹角,得出相应的冲击深度和冲击面积以及熔池内部速度分布。结果表明,在相同的条件下,随喷吹枪位的升高,射流形成的钢液凹坑直径变大,而冲击深度变小;随喷孔夹角的增大,射流冲击直径变大,而冲击深度减小。低枪位有利于增大熔池上层钢液流速,高枪位利于促进熔池下部钢液流动;喷孔夹角增大利于增大熔池表层高速区面积,但熔池中心底部低速区面积也随之增大。     

100t转炉用炼钢四孔氧枪射流数值模拟研究

利用Fluent软件对100t转炉超音速氧枪射流流场的速度进行模拟,模拟了普通超音速氧枪的炼钢氧气和钢液两相流动,包括氧气射流对钢水熔池的冲击面积和冲击深度,对实际炼钢生产有重要的指导意义。     

高效节能型旋流氧枪喷头的设计与应用

通过冷态气体射流试验对旋流氧枪喷头的设计参数作出评价,也为转炉氧枪操作提供合理的参考依据;结合工业试验情况,对旋流氧枪喷头参数进行修正,最终确定了莱钢集团银山型钢炼钢厂120、150 t转炉旋流氧枪喷头枪孔的最优夹角为13°,旋流角6.5°～7°,在充分发挥旋流氧枪优良的化渣、溅渣优势的同时,解决了熔池部位侵蚀严重难题,使旋流氧枪在中大型转炉中得以推广应用。采用此旋流氧枪喷头,尤其是在大废钢比情况下转炉过程化渣效果提升明显,氧气利用率提高,并能有效缩短吹炼时间1 min以上;溅渣时,熔池部位聚渣效果显著,溅渣效果提升明显,对于提高转炉炉龄有明显的促进作用。     

Simulation and Application of Swirl‐Type Oxygen Lance in Vanadium Extraction Converter

Stirring effects and impacting characteristics of conventional and various swirl‐type oxygen lances (Swirl angles are 5°, 10°, and 13°, respectively) on the molten pool were studied. The mixing time, impacting depth and impacting diameter were measured by water model experiment. The flow field characteristics of gas–liquid two phase flow were simulated using Fluent software. It is found that 10° swirl‐type oxygen lance injection can get the shortest mixing time which is only 47.6 s. The area surrounded by isovelocity is larger in molten pool when injecting by the swirl‐type oxygen lance. When injecting by the 10° swirl‐type oxygen lance, the area is the largest and the flow velocity of liquid steel is the highest. On this basis, the 10° swirl‐type oxygen lance was experimented in 150 t vanadium extraction converter. The experiment shows that the swirl‐type oxygen lance can guarantee the normal smelting process. Compared with the conventional oxygen lance, the reduction ratio of vanadium content in semi‐steel is 17.8%, vanadium extraction rate is increased by 5.1%, V₂O₅ grade of vanadium slag is increased by 0.93% and iron loss is reduced. It provides a new technology to improve the recovery of vanadium resources in converter.     

Simulation of Flow Fluid in the BOF Steelmaking Process

The basic oxygen furnace (BOF) smelting process consists of different chemical reactions among oxygen, slag, and molten steel, which engenders a vigorous stirring process to promote slagging, dephosphorization, decarbonization, heating of molten steel, and homogenization of steel composition and temperature. Therefore, the oxygen flow rate, lance height, and slag thickness vary during the smelting process. This simulation demonstrated a three-dimensional mathematical model for a 100 t converter applying four-hole supersonic oxygen lance and simulated the effect of oxygen flow rate, lance height, and slag thickness on the flow of molten bath. It is found that as the oxygen flow rate increases, the impact area and depth increases, which increases the flow speed in the molten bath and decreases the area of dead zone. Low oxygen lance height benefits the increase of impact depth and accelerates the flow speed of liquid steel on the surface of the bath, while high oxygen lance height benefits the increase of impact area, thereafter enhances the uniform distribution of radial velocity in the molten steel and increases the flow velocity of molten steel at the bottom of furnace hearth. As the slag thickness increases, the diameter of impinging cavity on the slag and steel surface decreases. The radial velocity of liquid steel in the molten bath is well distributed when the jet flow impact on the slag layer increases.     

底吹炼铜熔池液面波动数值模拟

底吹炼铜是新一代铜强化熔炼工艺。高压气流喷入熔池后产生的液面波动会不断冲刷炉膛壁面,导致壁面耐火材料的磨损。文中利用数值模拟方法对底吹熔池内气液两相流动过程进行研究,分析液面波动导致壁面的压力的变化。通过分析气泡在熔池内的分布及运动过程,得到了熔体对壁面冲刷侵蚀的主要原因。分析壁面压力随时间波动曲线,定义了冲击程度的概念,表征了熔池壁面因波动频率和压力变化而对壁面的磨损程度。模拟计算了单孔氧枪和多孔氧枪的流动过程,得出多孔氧枪气含率更高,冲击程度更小。计算分析了不同参数条件下的流场波动特性,结果表明在实验条件下氧枪角度为0°、气流速为0.7 m/s时,压力冲击程度最小,液面波动对壁面耐火材料的侵蚀最小。      

Three-phase Fluid Numerical Simulation and Water Modeling Experiment of Supersonic Oxygen Jet Impingement on Molten Bath in EAF

By means of the computational fluid dynamics software Fluent 6.3, a mathematical model of three-dimensional three-phase fluid flow field in the molten bath of electric arc furnace （EAF） with side accessorial oxygen lances was developed to study the transient phenomena of oxygen jet impingement on the molten steel and the molten slag. The water modeling experiment was carried out to verify the simulation results. The impingement of the supersonic oxygen jet caused impact dent on the molten steel surface accordingly. The area of impact dent changed almost in linear relationship to flow rate of oxygen jet, which can be expressed by a deduced mathematical equation. And the relationship between the impact force of oxygen iet and the correspondingly formed apparent static pressure on molten bath was obtained, which was in linear relationship and a direct proportion, and can also be expressed by a deduced mathematical equation.     

Simulation of Flow Field of Oxygen Lance Gas Jet Utilized for 50 t Converter

  Based on the operating conditions of oxygen lance utilized for a 50 t converter in Tangsteel, gas jet flow fields of three types of oxygen lances were simulated by FLUENT software. The influence of lance configuration and lance level on penetrating area was studied through cold model experiment. The results showed that the gas flow velocities of four hole, variable angle four hole and five hole oxygen lances declined rapidly with an increase in gas jet length within 1 m, 1 m and 08 m, respectively. Besides, the multi gas streams sprayed from these three lances should be syncretized at 16 m, 17 m and 14 m, respectively. At the highest lance level, the effective penetrating area of these three lances could be 0255 m2, 0385 m2 and 00907 m2, respectively. It was suggested that the effective penetrating area of variable angle four hole oxygen lance was the biggest, while that of five hole oxygen lance was the least. The validity of numerical simulation results was proved through cold model experiment. The lance level was suggested to be controlled in the range of 1-16 m, 1-17 m and 08-14 m for the four hole, variable angle four hole and five hole oxygen lances, respectively.     

50 t转炉四孔变角氧枪射流融合距离的数值模拟

采用Fluent软件模拟了50 t转炉四孔变角和非变角氧枪气体射流,研究了喷孔倾角对氧气射流流场和流股融合距离的影响。结果表明,在距喷头出口距离较近时,各流股独立为自由射流,随着距喷头出口距离的增加,各流股不断扩张,并在一定距离时融合成单股射流;非变角喷头A的流股融合距离为1.3 m,与冷态水模实验得出枪位1.3 m时炉口溅出量最大是一致的;变角氧枪B至I的对角喷孔倾角不同,射流流股融合了两次,大大降低了炉口溅出量;变角氧枪对角喷孔倾角相差0.5°较对角喷孔倾角相差1°时更有利于射流融合距离的增加;在研究喷孔倾角10.5°~11.5°/12.5°的9个喷头中,倾角11°/11.5°的喷头H射流融合距离最长,其理论炉口喷溅量最少。     

RH-KTB真空精炼中炉气二次燃烧的动力学研究

通过求解ｋ－ε－ｆ－ｗ方程组,模拟计算ＲＨ－ＫＴＢ真空处理过程中气相二次燃烧时的流场,温度场和浓度场,计算结果证明,ＲＨ－ＫＴＢ内气相二次燃烧主要发生在氧气射流的火焰烽面,ＣＯ２浓度高达６０％,温度达到２５００℃,燃烧后的氧气射流（Ｏ２浓度为３０％～６０％）冲击熔池,脱碳,产生大量ＣＯ炉气,压缩火焰烽面,使钢液面附近保持较高的ＣＯ浓度（〉６０％）,避免了钢液过氧化。