钢包出钢阶段吹氩搅拌去除夹杂物的模拟研究

针对钢包出钢过程建立了钢液-渣相-气相-氩气泡-夹杂物的五相数学模型，探索了钢包出钢过程中吹氩搅拌去除夹杂物的可行性，以及吹氩流量对流场、渣眼、夹杂物去除效率的影响规律。结果表明：吹氩搅拌可强化浇钢过程中钢液的流动行为，显著提升夹杂物的去除率。相较于未采用吹氩搅拌，当吹氩流量为100 L/min、出钢750 s时，夹杂物的去除率由80.74%提升至96.69%，流入中间包夹杂物的数量减少67.4%；随吹氩流量增加，渣眼尺寸增大，夹杂物去除速率增加，但去除效率变化不大，推荐吹氩流量为100 L/min。     

圆坯结晶器应用电磁搅拌的物理模拟

 以某钢厂 500mm圆坯连铸结晶器为原型,建立了1∶1的物理模型,通过机械搅拌模拟结晶器电磁搅拌,分析研究了电磁搅拌对结晶器内钢液的流动、夹杂物去除率的影响。试验研究表明：电磁搅拌使结晶器内的钢液有一定的水平切向速度,使搅拌区钢水温度的分布更加均匀,有利于结晶器内保护渣的均匀熔化。电磁搅拌能够把水口冲击的轴向速度变为径向速度,从而大大降低流股的冲击深度,能有效地促进夹杂物的上浮和热区中心的上移。但并不是搅拌强度越大,夹杂物的去除率就越高,试验表明,在相同时间内,当搅拌强度为48r/min左右时,夹杂物的上浮率最高。     

神户钢铁公司结晶器电磁搅拌技术的开发

结晶器电磁搅拌进行向下的纵向搅拌有可能减少板坯内的夹杂物数量和针孔气泡,尤其利于减少弧形板坯铸机内弧的夹杂物积聚。     

结晶器电磁搅拌对方坯中非金属夹杂物去除的影响研究

电磁力影响金属熔体中非金属夹杂物的分布及颗粒的传输速度,根据这一原理,进行了结晶器电磁搅拌对方坯中非金属夹杂物去除影响的试验研究.采用200、250 A和300 A这3种不同的EMS电流对方坯坯料进行了夹杂物分离和去除的试验,并采集样品进行能谱分析.结果表明,当结晶器的电磁搅拌参数为300 A电流和3 Hz频率时,铸坯...     

结晶器电磁搅拌对中碳铝镇静钢Φ450 mm圆坯中夹杂物的影响

采用夹杂物全自动分析仪研究了结晶器电磁搅拌对中碳铝镇静钢Φ450 mm连铸圆坯中的非金属夹杂物的数量、大小、分布的影响.结果表明,除边部区域外,电磁搅拌工艺条件下铸坯其他区域的夹杂物数量均低于无电磁搅拌工艺.电磁搅拌工艺条件下,随着从铸坯边部向中心移动,1～3μm的小尺寸夹杂物的数量逐渐减少,距离铸坯边部132～152...     

电磁搅拌对钢锭（坯）中夹杂物的影响

实验室试验结果表明,电磁搅拌能减少钢锭或钢坯中的非金属夹杂物数量。以不同搅拌条件比较,线性搅拌的效果最好,强旋转搅拌次之,弱旋转搅拌更差。延长搅拌时间有利于减少钢中夹杂物,但易使夹杂物集中到钢锭心部。电磁搅拌能消除弧形连铸坯内央杂物在内弧侧聚集现象。但旋转搅拌使夹杂物集中于心部,线性搅拌则比较轻抽微。     

连铸用电磁搅拌技术

电磁搅拌能够有效地增加铸坯等轴晶率,减少铸坯中的夹杂物和中心偏析等缺陷,已经成为改善铸坯和成品质量的重要手段之一。回顾了电磁搅拌技术的发展,介绍了电磁搅拌的类型。根据安装位置不同,电磁搅拌分为结晶器、二冷区和凝固末端搅拌。每种电磁搅拌具有各自的特点和冶金效果,电磁搅拌参数影响电磁搅拌的冶金效果。选择合适的电磁搅拌器和电磁搅拌参数,能够提高电磁搅拌的冶金效果。     

不锈钢中非金属夹杂物的危害及去除

介绍了不锈钢中非金属夹杂物的来源以及在钢中的危害，详细论述了在不锈钢精炼过程中，钢液中非金属夹杂物去除的机理，就钢液吹氩搅拌和镇静时间两个因素对钢中非金属夹杂物去除的影响进行了分析。     

连铸中间包内的流体流动和夹杂物去除

国外一项研究首先开发了安装流动控制装置和未安装流动控制装置的连铸中间包三维流体模型。结果表明，流动控制装置可以有效控制流人区的强烈搅拌，其它区域流动平稳。把中间包分为两个区，分别用不同的夹杂物去除机理计算了夹杂物去除的效果。     

钢的半固态电磁搅拌力场与组织转变

利用自制的高熔点半固态电磁搅拌装置对60Si2Mn钢半固态电磁搅拌力场及它对组织转变的影响进行了理论分析和实验研究。结果表明：电磁搅拌功率和频率直接影响电磁搅拌力，进而对金属熔体的流动形态有明显的影响。在一定频率范围内，搅拌功率加大，搅拌力随之增加；当搅拌功率达到一定值时(5kW)，继续加大搅拌功率将导致搅拌装置发热并恶化60Si2Mn钢半固态组织的转变效果。适宜的频率范围为20～50Hz。如果频率太高，屏蔽和钢熔体粘滞效应增大，将导致搅拌力下降；频率太低，涡漩电流减小，同样导致搅拌力下降。电磁搅拌力作用下的金属熔体流动形态由一个集中的大漩涡和较多的小漩涡构成。这种流动形态在宏观上可促使钢液的温度场和浓度场均匀化；微观上增加局部紊流密度。促使枝晶组织向球状组织转变。     

搅拌方式对多级钒页岩浸出槽内多相流行为的影响

钒页岩湿法提钒是一个多级浸出过程,现有的研究多将浸出槽视为单一的封闭容器,与现实情况不符,且作为新工艺的吹气搅拌机理和效果未有详细报道。采用数值模拟的方法,对比分析有无进出料口搅拌槽内流场与相分布,并研究搅拌方式对有进出料口搅拌槽内的多相流动行为的影响。结果表明：有无进出料口的搅拌浸出槽内流场有明显区别,同等机械搅拌条件下,有进出料口的近自由液面区域的死区由3.3%降低至1.8%,底部的死区则由1.07%降低至0.46%。当搅拌方式由仅吹气搅拌改变至仅机械搅拌时,顶层搅拌桨上部的区域流速由0.16 m/s增大至0.28 m/s,近自由液面的死区由8.5%降低至1.8%,底部死区的比例由2.68%降低至0.46%。而采用机械和吹气联合搅拌时,反而可能会削弱钒页岩的悬浮效果。     

An Experimental Prototype of an Innovative Fluid-driven Electromagnetic Stirring Technique

A new electromagnetic stirring technique that is driven by hydrodynamic forces was presented. This technique offers the following advantages. First,the stirrer can be immersed in the liquid metal,thereby significantly increasing the penetration depth of the electromagnetic forces and significantly improving the stirring efficiency; thus,this technique is particularly suitable for large-scale liquid metal. Second,under certain conditions,this technique can overcome difficulties that are encountered with traditional stirrers,such as accessing regions that are difficult to reach in working spaces with complex or narrow shapes. This stirrer also has a simpler structure than a traditional stirrer; thus,the design can be easily modified,and no external power supply is required. An experimental prototype was also presented for controlling the fluid flow rate,thereby controlling the electromagnetic force and velocity field of the driven liquid metal. The velocity distribution in a liquid Ga In Sn alloy under fluid-driven electromagnetic stirring was quantitatively measured using ultrasonic Doppler velocimetry( UDV). The primary results show that a remarkable velocity field has been achieved and that fluid-driven electromagnetic stirring is an effective means of stirring liquid metal. Finally,the potential applications of this technique in industry,along with key challenges,were discussed.     

Mathematical Model for Growth and Removal of Inclusions in Molten Steel under Gas‐stirring Conditions

A three‐dimensional mathematical model has been developed to predict growth and removal of inclusions during gas stirring through eccentric tuyeres in a ladle. In the model, the efficiency of inclusion removal is investigated under three different collision mechanisms: Brownian, turbulent and Stokes collision. The Importance of the three approaches of wall adhesion, Stokes flotation and bubble adhesion on inclusion removal is analysed and the efficiency of inclusion removal through three types of tuyeres in central, eccentric and multi‐tuyere form is studied. The results indicate that inclusion growth resulting from turbulent collision is most important and the effect of Stokes collision is remarkable with increased inclusion size, while inclusion growth resulting from Brownian collision is negligible. Removal by Stokes flotation is the main mechanism for large inclusions, while inclusion removal by wall adhesion is negligible. The smaller the bubbles are, the higher the efficiency of inclusion removal is. The type of tuyere arrangement has a great effect on inclusion removal. Inclusion removal in a 135t ladle with one eccentric tuyere is more efficient than in a ladle with central tuyere or multi‐tuyere design.     

含钒页岩浸出槽搅拌速度优化的数值模拟

含钒页岩浸出槽是钒页岩湿法提钒浸出段的主要操作单元,存在固相分布不均、槽底矿物易沉积等问题。通过数值模拟研究来对比分析搅拌桨叶双层同速以及异速方案下对搅拌浸出槽内固液两相流搅拌功率和效率的影响。结果表明,当搅拌桨叶双层同速由1.3 r/s改变至1.7 r/s时,死区由5.02 m³减少至2.03 m³,混匀时间由1 501 s降低至1 116 s,近自由液面平均速度也由0.32 m/s增大至0.56 m/s,因此搅拌桨转速选择1.7 r/s更为合适;搅拌桨叶双层异速可以得到与双层同速情况下基本一致的搅拌效果,当上层桨叶转速由1.5 r/s改变至1.7 r/s时,死区由2.95 m³减少至2.33 m³,混匀时间由1 261 s降低至1 146 s,近自由液面平均速度也由0.44 m/s增大至0.54 m/s。因此搅拌桨转速选择上层1.7 r/s、下层1.5 r/s能在保持较低的搅拌功率同时能得到较好的搅拌效率。     

Study on Absorption Rate by Eccentric Mechanical Stirring in Gas Injection Refining for Iron and Steel Making

In gas injection refining processes, a great amount of gas is injected into molten metal in short time, so that very large bubbles are inevitably formed. Wide dispersion of small bubbles in the bath is indispensable for high refining efficiency. Eccentric mechanical stirring with unidirectional impeller rotation was tested using a water model for pursuing better bubble disintegration and dispersion. Absorption rate are used to research on the influence law of the bubble dispersion and disintegration and gas-liquid absorption by the influence of, rotation mode, rotation speed and gas flow rate. Compared to the experimental results of absorption rate under eccentric stirring and centric stirring ,provide the scientific experimental and theoretical guidance for high-temperature experiment of hot metal desulfurization .According to experimental and theoretical analysis, this paper has studied various factors effecting on gas absorption process and volumetric mass transfer coefficient using the system of CO2-NaOH-H2O.The results show that:the volumetric mass transfer coefficient and absorption efficiency of CO2 can be increased under eccentric stirring mode, Because bubble disperse quickly with eccentric mechanical stirring, which results in promoting complete reaction between CO2 and NaOH, and improving the mass transfer coefficient and absorption. Volumetric mass transfer coefficient and efficiency of CO2 increase with the increasing rotation speed under the condition of eccentric stirring .But volumetric mass transfer coefficient and efficiency of CO2 decrease with the increasing rotation speed under the condition of centric stirring.     

An Experimental Study of Number Concentration Gradients of Inclusions during Deoxidation using Inductive and Gas Stirring

Concentration gradients of inclusions during inductive and gas stirring of AISI H13 tool steel in a ladle have been studied using a unique experimental technique at Uddeholm Tooling AB in Sweden. A specially designed sampling equipment, which allows five samples to be taken at the same time and at different depths was used. The aim was to experimentally quantify the existence of inclusion size population gradients in different positions of the steel melt. One experiment was carried out using induction stirring and one using gas stirring. The main findings from the induction stirring experiment was that i) concentration gradients of inclusions exist, ii) the number of inclusions decreases with stirring time in all positions, and iii) that the superficial positions show a more rapid decrease than the deeper ones. The main findings from the gas stirring experiment are that i) concentration gradients of inclusions exist, ii) the superficial positions are mostly affected by the gas plumes, and show a very pronounced decrease of the number of inclusions with stirring time, and iii) the deeper positions and also one of the superficial position (no “3”) shows no decreasing trend.     

Study on Desulphurization in Molten Iron Pretreatment Process Based on a New Stirring Method

In this work, numerical simulations for the flow characteristics in a tank of KR mechanical stirring or/and gas injection are performed using the Fluent software. The Eulerian multi-fluid model is employed along with the standard k-ε turbulence model to simulate the gas-liquid flow in the stirring tank. A multiple reference frame approach is used to model the impeller rotation. Combined the KR mechanical stirring method and gas injection method, a new gas injection plus mechanical stirring method is proposed. The present results show that the gas phase distributes widely in the eccentric gas injection plus mechanical stirring tank. Therefore, the gas holdup would be increased and the better gas-liquid mixing effect can be obtained in the gas injection plus mechanical stirring case.     

连铸结晶器电磁搅拌对夹杂物的影响

在连铸过程中 ,夹杂物对钢的质量有着重要影响。本文分析了结晶器电磁搅拌对夹杂物的作用机理 ,简要叙述了结晶器电磁搅拌对铸坯内夹杂物含量、大小、分布及其形态的影响     

基于CFD的大型底吹炉内熔体气动搅拌二维分析

在大型铜熔炼底吹炉冶炼过程中,气动搅拌对熔体混合和反应速率起着重要作用。为研究高温、密闭的大型底吹炉内熔体搅拌现象,采用计算流体力学(CFD)方法,建立了与实际装备相对应的等效几何模型,并通过数值模拟计算分析了大型底吹炉内气动搅拌机理。结果表明：气泡是大型底吹炉气动搅拌的基本单元,气泡周期性的生长脱离、上升形变、熔体表面破裂过程,将自身动能传递给熔体,促进熔池内成分均一化。持续产生的气泡对熔体做功,为熔池和入炉物料提供了充足的搅拌能。熔池内部形成核心搅拌区和澄清区,为铜冶炼过程的反应和分离提供了良好条件。研究得出的气动搅拌机理对今后大型底吹炉优化设计和工程应用起到了指导作用。     

铝熔炼电磁搅拌装置辅助拖车的添加

介绍了电磁搅拌装置在铝合金熔炼过程中的应用,以及一拖三电磁搅拌装置因拖链较长遇到的问题,通过采取增加辅助拖车的措施来支撑保护拖链,满足企业安全生产的目的。