Online forecasting model of tundish nozzle clogging

A nozzle clogging online forecasting model based on hydrodynamics engineering was developed, in which the actual flow rate was calculated from the mold width, thickness, and casting speed. There is a linear relationship between the theoretical flow rate and the slide gate opening ratio as the molten steel level, argon flow rate, and the top slag weight are kept constant, and the relationship can be obtained by regression of the data collected at the beginning of the first heat in each casting sequence when the nozzle clogging does not occur. Then, during the casting, the theoretical flow rate can be calculated at intervals of one second. Comparing the theoretical flow rate with the actual flow rate, the online nozzle clogging ratio can be obtained at intervals of one second. The computer model based on the conception of the nozzle clogging ratio can display the degree of the nozzle clogging intuitively.

Effects of argon blowing at tundish upper nozzle on multiphase flow behavior in nozzle

In continuous casting,the argon blowing at the tundish upper nozzle is usually used to prevent nozzle clogging,whose effect is closely related to the migration of argon bubbles and the flow behavior of the liquid steel in the nozzle.Here,to investigate the effects of argon blowing at the tundish upper nozzle on multiphase flow behavior in nozzle,a threedimensional model of the tundish–nozzle–mold was established for numerical simulation.The results indicate that the argon bubbles injected from the inner wall of the tundish upper nozzle first move downward along the nozzle wall under the action of the liquid steel.As the distance from the tundish upper nozzle increases,the argon bubbles gradually diffuse to the center of the nozzle.Compared with no argon blowing,the liquid steel velocity increases in the center of the nozzle and decreases near the wall with argon blowing.With increasing the argon flow rate,the concentration of bubbles in the nozzle increases,and the process of bubble group diffusion to the center region of the nozzle speeds up.This in turn increases the liquid steel velocity at the center of the nozzle but reduces near the wall.With increasing the casting speed,the concentration of bubbles in the nozzle decreases,the length of the bubble group near the nozzle wall is extended,and the liquid steel velocity at the center region and near-wall region of the nozzle increases.The mechanism of argon blowing at the tundish upper nozzle to prevent nozzle clogging is mainly realized by the isolation effect of the argon bubble group on the inner wall of the nozzle.

Technology of nitrogen-argon mixed gas blowing on the tundish stopper

Bubble defect is one of the main defects of an automobile sheet.To solve this defect,the technology for nitrogen-argon mixed gas blowing on the tundish stopper is developed,the theoretical research on nitrogen absorption in the molten steel is performed,the nitrogen-argon mixed gas blowing equipment is developed and experimented in the plant.The expected effect is achieved in the industrial test,and the slab inclusion density and quality degradation ratio of the automobile sheet are significantly reduced.

Analysis on clogging of submerged entry nozzle in continuous casting of high strength steel with rare earth

The type of inclusions in tundish steel and the formation mechanism of the submerged entry nozzle(SEN)clogging in the continuous casting of the rare earth(RE)high strength steel without calcium treatment were studied based on the plant trials and thermodynamic calculation.It was found that Ce_(2)O_(3) and CeAlO_(3) in tundish molten steel were transformed into Ce_(2)O_(2)S+CaO-Al_(2)O_(3) with the size of 2-3 lm during cooling.When the flow velocity of molten steel on surface of the SEN was slow due to the boundary layer effect,Ce_(2)O_(3) inclusion in molten steel reacted with Al_(2)O_(3) in the SEN refractory to form CeAlO3.With the continuous erosion of molten steel and reaction,the compositions of CeAlO_(3),Al_(2)O_(3) and CaO were aggregated,and the clogging layers with different zones were formed on surface of the SEN.Meanwhile,a small amount of molten steel remaining in the arc zone and corner zone of the SEN formed solidified steel.When calcium treatment is canceled,the reaction probability between inclusions in molten steel and refractory should be reduced by improving the material and shape of the SEN.

冷镦钢SWRCH22A生产工艺优化与实践

介绍北营炼钢厂在现有设备工艺条件下,分析生产冷镦钢SWRCH22A过程中间包水口结瘤的原因,优化过程生产工艺,制定结瘤控制措施,确保轧制质量控制。

双长水口七流中间包结构优化的数值物理模拟

以某钢厂双长水口七流方坯中间包为研究对象,进行中间包优化研究。建立1∶4水模型并开展水模实验,对水模实验结果进行分析,研究导流孔位置和上仰角度对双长水口中间包流场的影响,选取最优的控流装置。同时,运用商业软件ANSYS Fluent对原型中间包和优化中间包进行流场和温度场耦合计算,并与水模型结果相互验证。结果表明,优化前后停留时间从127 s增至253 s,死区比例从57.13%减至24.10%,停留时间标准差从21.74减至10.87,浇注区纵截面浇注温度最大温差从4.7 K降至1.2 K,各流水口温差明显降低,中间包各水口一致性增加,流动更加均匀。

多流中间包少流浇注过程的研究现状

在连铸过程中,多流中间包经常会出现少流浇注现象。针对这一现象,国内外学者通过运用物理模型和数学模型,对少流操作过程的中间包内流场、温度场以及夹杂物去除进行研究。通过对不同流数的中间包进行分类,并对超多流、六流和四流中间包少流操作研究现状进行分析研究,以期探寻合理的水口关闭方案。

中间包耐材的使用与管理

通过对中间包耐材组成和日常工作中出现的耐材损毁问题,从耐材设计、使用和管理方面进行逐一分析,找出原因并提出解决措施,保证了耐材的安全使用。

数值模拟在不锈钢中间包冶金中的应用

利用数值模拟的方法对不锈钢中间包流场以及中间包RTD曲线进行数值模拟。结果表明:长水口浸入深度在500mm时,中间包钢液的流场最合理,最大停留时间为512s;死区体积最小,体积分数为10.175%,比200mm和350mm时小7.2%,比650mm时小35.9%;中间包容量扩大后,连铸中间包钢液流场更加合理,平均停留时间增加了7s,死区体积减小了5%;用气幕挡墙后,改变了钢液的流动方向,有效延长了停留时间,减少了死区;在下挡墙增加小孔并不会使流场发生明显改变。

12机12流方坯连铸机高效生产实践

对制约宣钢150 t炉区1号连铸机高效生产的因素进行分析,并针对性地采取优化冷却系统、优化耐材质量、优化中间包快换技术等措施,实施优化后,连浇率突破72.22%,适应了新生产模式下的铁钢平衡,实现了连铸高效化生产。

Process optimization of billet continuous caster and practice verification

This study analyzes the factors of influence on 0~# continuous caster in No.1 Steelmaking Plant of Xinjiang Bayi Iron & Steel Corporation(hereinafter referred to as Basteel).Diameter of tundish upper nozzle is small,and the molten steel leakage accidents have been greatly manifolded in the high casting speed.In order to increase yield of 0~# continuouse caster in No.1 Steelmaking Plant of Xinjiang Bayi Iron & Steel Corporation,and a series of amelioration measure was put forward.Through enlarging diameter of tundish upper nozzle(fromφ21 mm toφ21.5 mm ),after the water distribution of the secondary cooling was optimized.Based on stabilizing the quality,improving the average casting speed and work rate of the caster,the capacity of the billet continuous caster was improved.A better results was gained;the average casting speed had been increased from 3.04 m/min to 3.21 m/min.Production of the caster had been improved from 1 005 179.926 t in 2008 to 1 040 853.075 t in 2009.Quality of the concasting billets and production had also been stabilized.

中间包喂稀土水口结瘤机理的研究

在现场进行中间包喂稀土实验,对水口结瘤样进行扫描电镜能谱分析和X-射线衍射分析。结果表明,在本实验条件下,水口瘤的主要组分为高熔点的稀土铝酸盐和凝钢;结瘤物是以钢中稀土与水口耐火材料相互作用形成的稀土铝酸盐为衬底,钢中的夹杂物在此基础上粘附烧结而形成。

等离子体制取ZrO_2在连铸中间包的应用

在150kW的等离子体装置中,制取出脱硅锆(88.60％～96.90％ZrO_2)和稳定型氧化锆(ZrO_2≥91.54％,MgO≤5.39％)。研究了温度、时间和配碳量等因素对去除锆英石中SiO_2的影响规律。用脱硅锆代替化学提纯法生产的纯氧化锆,试制了连铸中间包用的定径水口(75％ZrO_2)产品,经使用,已能满足工业生产的要求。

连铸中间包水口堵塞机理及防止措施

介绍了连铸中间包水口堵塞的主要类型,总结分析国内外关于Al2O3黏附堵塞的机理及其防止措施的研究现状,并讨论防止水口堵塞措施的研究方向.针对水口堵塞问题,国内外开展了多方面防止水口堵塞措施的研究,取得了一定的效果,但水口堵塞问题仍未得到彻底解决.前人的研究结果表明,改进水口材质是可能从根本上解决水口堵塞的方法.目前,单一材质已不能满足连铸发展的要求,多样化、复合化是水口材质的发展趋势,其中碱性的尖晶石材料和低浸润材料将是重要的方向.夹杂物向水口内壁传递是水口堵塞的控制性环节,由于钢液高温不可见,目前多采用数值模拟方法进行研究.基于EDEM-FLUENT耦合的模拟方式可以更客观地描述夹杂物颗粒传递过程和考虑颗粒间的相互作用,将是数值模拟研究高熔点质点黏附机理的一个重要方向.

利用弯水口提高离心式中间包钢液旋流强度的研究

针对离心式中间包电磁驱动旋流强度不充分的问题,探讨在不增加外加能量或动力的情况下,利用弯水口将钢包内钢液的位置势能转化为水平出流动能以增强旋转室内钢液旋流强度的可能性．利用水模型观察实验,结合数值模拟手段,证明了弯水口注流可以增强离心式中间包旋转室内的旋流强度,在本研究条件下可以使最大速度值增加约15%．

连铸中间包用耐火材料的使用现状及发展

介绍了近５年来有关连铸中间包用主要耐火材料的使用现状，并提出了今后的发展方向。

宝钢1450板坯连铸中间包自动开浇过程控制技术

提出了中间包自动开浇控制的两个阶段。介绍了宝钢 1 45 0板坯连铸中间包自动开浇技术的发展及粘合式开浇管的开发 ;阐述了自动开浇的理论计算、硬件配置和系统流程 ,通过试验 ,找到了软件设置的要点以及对硬件管理的要求 。

离心式中间包流场的大涡模拟研究

为了研究离心式中间包的流动过程,采用大涡模拟（LES）方法针对3种不同情况,即（a）电磁力加直水口注流;（b）利用钢液的位能使用弯水口注流;（c）电磁力和弯水口注流共同作用,考察了影响旋流强度和中间包内流动结构的工艺参数.结果表明,LES方法可以成功模拟离心式中间包的三维湍流流场.与单纯电磁力或单纯弯水口相比,旋转电磁力和弯水口共同作用时可使水平面的旋流强度显著增强.在原有电磁力作用的基础上,使用弯水口注流可比原流场最大速度值增加约15%～19%.

连铸防堵水口的设计原理及其应用

简要叙述了中间包水口堵塞的类型及其特征 ;分析了防堵水口设计原理及其关键尺寸的确定原则 ;

防止浸入式水口堵塞的研究与应用

介绍了一种连铸中包采用浸入式水口和塞棒同时吹气工艺，防止浸入式水口堵塞技术。研究结果表明：采用这种工艺后，可使１５ＭｎＨＰ钢的连铸炉数由原来的４炉提高到６炉。中包—铸坯夹杂去除率提高了１０．４％。