Design optimization of flow control device for multi-strand tundish

The fluid flow phenomena in tundish have a strong influence not only on the uniform of composition and temperature of bath, but also on the separation of non-metallic inclusions, especially for the multi-strand tundish. A water model of a multi-strand tundish has been set up based on the Froude number and Reynold number similarity criteria. The effect of dam+weir and baffle on the uniform of composition and temperature of bath for different nozzles has been studied. The residence time distribution curves of the fluid flow were measured by SG800. Comparing the photos of the flow pattern in tundish, the optimum arrangement of baf-fle+dam was obtained. This new structure is benefit not only to uniform the temperature among different SENs (submerge entry nozzles) but also to separate the non-inclusions from the liquid steel, it can be widely used in multi-strand tundish.     

板坯连铸中间包内钢液流场和浓度场的数值模拟

采用FLUENT软件对板坯连铸中间包内的流场和浓度场进行数值模拟,分析中间包内有无挡墙以及挡墙参数变化引起中间包内流场、浓度场的变化情况。模拟结果表明,湍流控制器与挡墙的优化配合使中间包内钢液的平均停留时间由502 s延长至573 s,死区体积分数由29.7%降为14.4%,优化挡墙与挡坝参数有利于钢液温度和成份的均匀,及夹杂物的上浮去除。     

中间包控流装置的物理模拟研究

根据相似原理,建立1∶3的物理模拟模型,通过正交试验考察了挡渣堰、导流坝组合控流装置对中间包流场的影响。研究结果表明,堰坝间距是影响流场的主要因素,优化控流组合方案为：挡渣堰距注入流中心线距离1 200 mm,挡渣堰下沿距包底距离500 mm,导流坝高度360 mm,堰坝间距300 mm.优化后中间包流场趋于合理,钢液在中间包内的停留时间延长,活塞流体积增大,死区体积减小.     

两流板坯连铸中间包结构优化水模实验研究

通过两流板坯中间包水模实验,研究了抑湍器以及不同控流装置的组合对中间包流动特性的影响.结果表明,合理使用抑湍器能延长开始响应时间,提高平均停留时间和活塞流体积.抑湍器和垱坝组合控流效果良好,且结构简单.由抑湍器、垱坝和挡渣堰组成的控流装置使中间包流场更加合理,优化后的中间包平均停留时间由原先的188 s提高到218 s,活塞流体积分数由3.50%提高到15.41%,死区体积分数由41.57%降低到32.15%.     

Dispersive bubble wall——a new method of flow control in tundish

Tundish is the last refractory vessel in the steelmaking process. The fluid flow phenomena in tundish have a strong influence on the separation of non-metallic inclusions. The dispersive bubble wall （DBW） is a new method in tundish metallurgy. A water model of a multi-strand tundish has been set up based on the Froude number and Reynold number similarity criteria. The effect of DBW＋weir on the flow pattern has been studied. The results show that this new structure of DBW＋weir is beneficial not only to uniform the temperature among different submerge entry nozzles but also to separate non-metallic inclusions from liquid steel. The DBW can capture the particles of non-metallic inclusions and make them float up to the surface.     

Dispersive bubble wall--a new method of flow control in tundish

Tundish is the last refractory vessel in the steelmaking process. The fluid flow phenomena in tundish have a strong influence on the separation of non-metallic inclusions. The dispersive bubble wall (DBW) is a new method in tundish metallurgy. A water model of a multi-strand tundish has been set up based on the Froude number and Reynold number similarity criteria. The effect of DBW weir on the flow pattern has been studied. The results show that this new structure of DBW weir is beneficial not only to uniform the temperature among different submerge entry nozzles but also to separate non-metallic inclusions from liquid steel. The DBW can capture the particles of non-metallic inclusions and make them float up to the surface.     

漩流中间包流场的数值模拟

采用CFD软件Fluent对漩流中间包内的流场进行了数值模拟,分析了漩流中间包内的流场特征,以及漩流室的加入,中间包内的流动形态.模拟结果表明,由于漩流室的加入使湍动能耗散主要集中在漩流室内部,有利于夹杂物的聚合长大;漩流室的加入可改善钢液的流动状态,利于夹杂物的上浮。由于入口位置的非对称布置,造成了漩流中间包内的流场在入口区呈明显的非对称分布,这些结果为进一步优化漩流中间包内漩流室的位置和中间包挡墙参数提供了理论依据.     

板坯中间包控流装置结构优化的水模研究

根据相似原理,按照1：2比例对中间包建立水力学模型。考虑坝高、堰离底部高度、坝堰间距、堰与长水口注入点间距等参数对中间包内流场的影响,依据工厂实际工艺参数设计实验方案。对实验结果进行分析,结果表明：对原中间包结构进行优化,减小堰离底部距离及堰与注入点间的距离,钢液在中间包内响应时间由69.0 s延迟至75.0 s,平均停留时间由418.0 s增长至555.4 s,死区体积比例则由28.4%降至18.3%。     

Improvement of tundish shape and optimization of flow control devices for sequence casting heavy steel ingots

The metallurgical effect of a round tundish used to cast heavy steel ingots in machine works at present was evaluated through water modeling experiments.The flow control devices of the improved oval tundish,which was used instead of the round tundish,had been optimized.The results show that the residence time of the round tundish is short,its inclusion removal efficiency is too low,and it has more dead zones and an unreasonable flow field.Compared with the round tundish,the improved oval tundish with the optimized weir and dam has a better effect:its minimum residence time is prolonged by 38.1 s,the average residence time is prolonged by 233.4 s,its dead volume fraction decreases from 26％ to 15％,and the ratio of plug volume fraction to dead volume fraction increases from 0.54 to 1.27.The inclusion removal efficiency also increases by 17.5％.     

中间罐中吹气搅拌对钢水流动的影响

连铸中间罐内钢水的流动对于成分和温度的均匀，非金属夹杂物的去除都有重要影响。本文在相似原理基础上，建立了中间罐水力学模型，通过刺激－响应试验，夹杂物模拟及高速摄影流场显示实验，研究吹气搅拌对钢液流动及夹杂物去除的影响。     

Influence of flow control devices on metallurgical effects in a large—capacity tundish

The influence of flow control devices on metallurgical effects in large-capacity tundish has been studied carefully with elements tracing,sampling and theoretical prospecting,The results from the studies are(1) in the continuous casting of clean steel,bad control of tundish operation may deteriorate the cleanliness of steel;(2) the cleanliness of steel is deteriorated mainly at the unstady state;(3) large amount of macro inclusions come from the top slag and the refractory of tundish;(4) installing dam and weir can improve the cleanliness of steel and lighten the influence of steel fluctuation;and (5) the result of theoretical calculation suggests that the inclusions larger than the critical size of 92.6um can be floated out from the tundish bath completely.     

Fluid flow in large-capacity horizontal continuous casting tundishes

The configuration of the tundish for a two-strand horizontal continuous caster was designed and optimized through water modeling. Three designs of the tundish were studied: the original tundish without any flow control devices, the tundish with a turbulence inhibitor at the bottom, and the tundish with an inlet launder and an inclined dam. The residence time, the location and size of the dead zone, and the fluid field pattern were investigated. At the same time, the asymmetry flow field and wavy inlet jet in the horizontal tundish were observed and the reasons for them were discussed. The results indicate that the tundish with an inlet launder and an inclined dam is the best of the three designs.     

板坯连铸中间包钢液流场的数学模拟

利用计算机数学模拟的方法,对中间包内钢液流场进行研究,以济钢一炼钢厂4#板坯连铸中间包为模型,以挡墙分别距入口处、挡坝间的距离,挡墙和挡坝高度为影响参数,对板坯连铸中间包流场进行优化设计.得出有利于生产的设计数据.     

连铸中间包内流场控制优化水模实验研究

根据相似原理,研究了原设计方案和优化改进方案对中间包流场的影响。采用刺激-响应实验方法测得中间包流体的平均停留时间分布(RTD)曲线,并得到不同方案控流装置对中间包流体流动的影响,从而优化对中间包流场的控制。研究结果表明:方案4中活塞区体积分数增大了42.44%,钢液平均停留时间延长了500s左右,并且提高了中间包各流之间的钢液均匀性,从而促进夹杂物的上浮去除。     

Mathematical modeling of fluid flow, heat transfer and inclusion transport in a four strand tundish

Mathematical simulation was used for trouble-shooting and optimization. By the mathematical simulation, fluid flow and beat transfer of molten-steel in a four-strand tundish of a billet caster under different conditions （bare tundish and tundish with flow control device） were analyzed, The results showed that （1） the tundish with flow control device （FCD） has an important effect on the fluid pattern and temperature distribution; （2） the unsteady, solving method was used to model the inclusion motions at different time perthds, and it showed that the FCD is advantageous to separate the nonmetallic inclusions. According to the simulation results, the main problem existing in the industry preduction was found, and some helpful rneasurements were executed. Consequently, the large nonmetallic inclusions were separated, and the content of total oxygen was reduced. The qualily of steel was greatly improved.     

Dissymmetric flow phenomenon in a multistrand tundish

The dissymmetric flow phenomenon exists in a symmetric multistrand tundish. It was studied by the physical simulation experiment. The fundamental flow characteristic of dissymmetry was analyzed. The asymmetry of the flow field, the temperature field, and the inclusions distribution without flow-control devices (FCDs) were compared with those with FCDs. It is proved that the asymmetry of the flow and temperature field along the outlets at the long range is more obvious. The symmetric FCDs installation has a slight effect on the dissymmetric temperature field, simultaneously, the symmetry of the average residence time and the fluid flow pattern has improved, and the fluid flow in the tundish has been more reasonable. In case of a symmetric multistrand tundish having a large volume, the influence of the dissymmetric phenomenon should be considered and the flow behaviors in the whole tun- dish should be studied completely.     

板坯连铸中间包结构优化的研究

结合某公司双冲击点板坯中间包生产现状,利用水模实验对中间包内钢水流动特性进行了研究.结果表明：原中间包结构存在明显的短路流,钢水停留时间偏短,死区体积分率偏高,不利于夹杂物上浮去除.同时,由于在高度较大的两湍流控制器间钢水不能流出,影响金属收得率.这种具有双冲击点的中间包,应按照对称的两个单流板坯中间包进行结构优化.采用小高度湍流控制器加上下挡墙的控流方式时,由于钢水流经路径增长和全混流体积分率增加,响应时间增长,死区体积分率显著减小至15%以下,有利于夹杂物上浮去除.同时,将小高度湍流控制器和门式开孔导流坝相结合,残钢量显著减小,有利于提高金属收得率.     

Numerical simulation of flow phenomena and optimum operation of tundish

1　INTRODUCTIONDuringthecourseofcontinuouscastingsteel,theflowofliquidsteelintundishwasafairlycomplexprocesscontainingmomentumtransfer,masstransfer,energytransferandphase changeofmultiphasecomponents .Ac cordingtoRefs.[1,2 ],someinfluencingfactorsincastingsteelwerefound ,includingthecompositionofliquidsteel,thetechnicalparametersoftundishandre oxidationofmoltenmetal.Theprocesswouldaffectdirectlysurfacedefectsandinternalstructureformationofthecastingsteelproductsaswellastherealizationofhig…     

单侧孔长水口优化异型四流中间包流场

采用数值模拟方法研究了不同形式长水口下异型四流中间包的钢液流场和停留时间分布特征.数值结果表明：原型中间包存在较大的死区,各流流动情况存在着巨大的差异,而把直通型长水口替换成单侧孔型长水口之后,中间包死区比例减少,各流流动差异性基本上被消除.在挡墙的左侧产生了旋转流场,有利于夹杂物的碰撞聚合和去除.     

中间包自由表面的数学模拟

为了更好的发挥中间包在冶金中的作用,研究了坝高、堰深、坝堰间距及中间包水口出流速度等因素对中间包自由表面的影响,试验通过营造中间包水口附近平稳的钢液面来减少卷渣,从而达到提高铸坯质量的目的。