板坯连铸水口内钢液流动的数值模拟

 运用CFX计算软件研究了大通钢量工况下板坯浸入式水口流场,分析了水口结构、结晶器流动控制方式、水口吹氩等对浸入式水口流场的影响。研究表明,适宜的水口结构和控流方式组合能获得最优的水口出口流股形态和稳定均衡的流场。在大通钢量下,塞棒、底部凸起水口结构是最佳组合。不适宜的工艺组合形成并加重水口偏流,造成结晶器初始坯壳的不均匀冲刷和液面涡流,进一步诱发水口堵塞、水口结瘤、结晶器非稳态和不均衡传热,最终导致铸坯缺陷甚至诱发拉漏事故。     

薄板坯连铸机浸入式水口的结构优化

以兰州钢厂薄板坯连铸机为原型,采用信噪比正交实验设计的方法,通过流场显示、波高测量及冲击力测量,研究了高拉速条件下,浸入式水口的出口角度、出口面积和插入深度对结晶器内流场变化的影响及变化规律.试验结果表明:出口面积比为1.3,出口角度向下倾斜5°,浸入深度为280mm,可以满足提高技速后生产的需要.     

连铸用浸入式水口的进展及展望

介绍了浸入式水口的结构和发展及其本质的发展历史过程,着重介绍了不同时期不同材质浸入式水口的优缺点,并对浸入式水口的发展趋势进行了分析.     

CSP连铸浸入式水口结瘤案例研究

研究了CSP连铸浸入式水口结瘤两种案例。案例曲线表明,塞棒开度和结晶器液面波动是钢水浇铸过程中最重要的特征参数。薄板坯连铸铝镇静钢中间包水口结瘤是高熔点夹杂在水口内壁的聚集。生产不稳,积压钢水在LF多次处理,产生细小的高熔点夹杂难以去除;软吹钢水“露眼”和开浇烧氧再生高熔点夹杂来不及去除都会导致水口结瘤。钙处理主要是球化夹杂,改善钢水可浇性。即使Ca／Als（钙／酸溶铝）和Ca／Alin（钙／酸不溶铝）都合适,夹杂物绝对量大,钢水可浇性仍较差,水口容易结瘤。     

连铸板坯浸入式水口吹氩工艺研究

研究了浸入式水口吹氩对连铸板坯质量影响的问题。进行了实验室物理模拟、现场取样,实施改进条件后单流连铸机稳态与非稳态下现场试验。主要采用的方法为水模试验、低倍检验与金相分析。提出应将水口不堵塞作为吹氩工艺设置的最终目标,而吹氩造成的液面波动等情况可作实际控制时的间接依据。研究表明,为防止堵塞,同样断面条件下应设置为高拉速吹气量小而低拉速大。在保证生产顺行情况下,通过对结晶器吹氩气量的优化设置,可降低铸坯针孔等缺陷的产生。     

连铸浸入式水口水模型研究

为控制结晶器内流场，对浸入式水口的底部和侧孔形状进行了研究，确定了合适的底部及侧孔形状。     

SEN底部形状对结晶器内钢液流场和温度场的影响

针对某钢厂板坯连铸结晶器及浸入式水口(SEN)的结构参数,建立了描述结晶器内钢液流动的三维数学模型,应用FLUENT软件对结晶器内钢液的流场和温度场进行耦合计算,分析SEN底部形状对结晶器内流场和温度场的影响,并利用水模试验对钢液的流动行为进行了验证。结果表明:凸底水口出口附近钢液的速度较大,流股的冲击深度较大,使结晶器内高温区下移,不利于凝固坯壳的生长;平底水口自由面速度较大、温度较高,有利于保护渣的熔化,但易产生液面裸露现象;凹底自由面速度较小、温度较低,有利于液面稳定。     

A Study on the Nonmetallic Inclusion Motions in a Swirling Flow Submerged Entry Nozzle in a New Cylindrical Tundish Design

Metallurgical and Materials Transactions B - Different sizes and shapes of nonmetallic inclusions in a swirling flow submerged entry nozzle (SEN) placed in a new tundish design were investigated by...     

矩形坯连铸浸入式水口优化物理模拟

通过水模实验优化水口结构形式和工艺参数,解决某钢厂165 mm×280 mm矩形坯连铸机在生产中出现的夹渣、鼓肚和粘结漏钢问题.优化范围包括水口的插入深度、出口倾角以及出口侧面和横断面的面积比.结果显示不同的水口形式对流场有不同的影响,目前使用的直通型水口正是造成生产中出现问题的症结所在.通过实验优化出适合165 mm×280 mm矩形坯的9#双侧孔水口和42#四孔水口.     

大方坯连铸四孔浸入式水口的应用研究

针对攀钢大方坯连铸结晶器,采用四孔水口浇注重轨钢.通过物理模拟实验,测量并分析了结晶器内液面波动、冲击压力和冲击深度等因素,结合数值模拟结晶器内流体流动现象的结果,发现合理的四孔水口形式更适合浇注质量要求高的重轨钢.现场试验结果表明,采用推荐的四孔浸入式水口浇注,重轨钢铸坯表面无清理率100%,铸坯合格率达到99.95%.     

Combined Electromagnetic Tomography for Determining Two-phase Flow Characteristics in the Submerged Entry Nozzle and in the Mold of a Continuous Casting Model

This article describes experiments on the combined determination of the distribution of liquid metal and argon in the submerged entry nozzle (SEN) and of the flow in the mold of a small-scale physical model of a continuous slab caster. For visualizing the metal distribution in the SEN, mutual inductance tomography (MIT) is applied, while the flow in the mold is determined by contactless inductive flow tomography (CIFT). The results of the latter are validated in part by ultrasonic Doppler velocimetry (UDV). Accompanying measurements provide information about the levels in the tundish and in the mold, as well as on the pressure in the SEN. Depending on the gas flow rate, various flow regimes are identified, among them pressure and mold level oscillations, transitions between double and single vortex flows, and transient single port ejections.     

Suppression of Effect of Uneven Velocity in Submerged Entry Nozzle in Round Billet Continuous Casting Process Using Electromagnetic Swirling Flow

Sliding gate control system is widely employed in continuous casting process of steel to control flow rate of molten steel.As molten steel passes through a sliding gate,uneven flow develops.This will cause asymmetrical distribution of flow and temperature field in mold consequently,formation of vortex near the nozzle and entrapment of CC powder into the molten steel.etc,which have negative effect on process productivity and product quality.To suppress the uneven flow,electromagnetic swirling flow has been proposed to impose on the flow in submerged entry nozzle below the sliding gate.In this study the uneven flow developed by incompletely open sliding gate and the suppression of this uneven flow using electromagnetic swirling flow are numerically studied in round billet continuous casting of steel process.The improvement of the flow and temperature filed in the submerged entry nozzle and mold are investigated.It is found that:The uneven velocity in nozzle can be suppressed by electromagnetic swirling flow,and the flow and temperature field in mold be improved obviously;With the increase of electromagnetic swirling intensity,the effect of uneven flow can be almost completely suppressed.     

Calculation Accuracy and Efficiency of a Transient Model for Submerged Entry Nozzle Clogging

Metallurgical and Materials Transactions B - A transient numerical model was proposed and validated by the current authors for nozzle clogging (Barati et al. in Powder Technol 329:181-98, 2018)....     

含钛不锈钢连铸浸入式水口结瘤的研究

为了解决含钛不锈钢连铸过程中浸入式水口的结瘤问题,采用扫描电镜和 X射线微区衍射等方法分析了AISI 321不锈钢连铸水口结瘤物的物相,探讨了浸入式水口的结瘤机理。结果表明:水口结瘤物中的物相主要有CaO·TiO2 -MgO·Al2O3 和金属,其中CaO·TiO2- MgO·Al2O3 主要来自于钢液中的夹杂物。喂钛线后吹氩搅拌过强使钢液面裸露和浇铸时的二次氧化会显著增加钢中CaO·TiO2- MgO·Al2O3 双相夹杂物的数量,导致结瘤层明显变厚。冶炼过程中采用低铝硅铁(ωAl=0 05%)还原,且不加铝、Ca- Si脱氧,或者在加 Ca Si后通过喂钛线前的吹氩弱搅拌尽可能排除钢中CaO- SiO2、CaO- SiO2 Al2O3 等夹杂物,严格控制二次氧化,可使喂入钛线后钢中CaO·TiO ·Al O 双相夹杂物数量明显减少,从而改善水口结瘤现象。     

八钢板坯连铸中包浸入式水口结构的优化

总结了板坯连铸结晶器浸入式水口对结晶器流场的影响,通过数学模拟及现场大量试验。选定了适合八钢板坯连铸现场条件的浸入式水口,解决了结晶器角部扰动的问题,提高了板坯质量。