底吹气中间包内流动与夹杂物控制

以宝钢集团梅山钢厂1台连铸中间包为原型,采用水模型的方法对底吹气中间包内的流动和夹杂物控制进行研究.结果表明,采用自行设计的装置进行底吹气,能够在中间包内形成均匀、稳定而又细小的气泡;底吹气能够在中间包内形成微气泡形式的"气幕挡墙","气幕挡墙"的形成能有效地破坏中间包内"层流"结构的流动形式,避免形成短路流动,提高平均停留时间,缩小死区体积分率;在吹气位置的选择上,采用中部位置(B2)进行吹气,效果较好;采用底吹气的方式可以实现对中间包内流动的控制,且不需要大的气体流量;底吹气有利于中间包内夹杂物的去除.     

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。     

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%.     

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.     

镁氯化过程气流分布的模拟研究

根据相似原理，通过模型试验再现了镁氯化炉内的气流分布状态，研究了鼓风速率、风口角度、料面形状对气流分布的影响，研究结果对控制氯化炉内的气流速度分布有一定的指导意义。     

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.     

超声波钢包精炼冷态模拟

以某钢厂180t钢包为原型,进行超声波改善钢包熔池搅拌效果的冷态模拟实验。通过记录pH计示数变化研究底吹气体搅拌均混时间及超声波搅拌均混时间。实验结果表明,在底吹空气水模实验中,当吹气位置在距离中心为0．33R,流量为0．1m3／h时,底吹气体搅拌所需的均混时间最短为50s;超声波水模实验中,当波源伸入钢包的中心液面下25cm处,输出功率1．8kw,均混时间最短为35s;在超声波和底吹气体联合实验中。当吹气位置在距离中心为0．33R,流量为0．1m^3／h,波源伸入钢包的中心液面下25cm处,输出功率1．8kw时,均混时间最短为48s;可以看出超声波可明显缩短钢包均混时间,改善钢包精炼动力学条件。     

50吨转炉顶底复合吹炼水力学模型实验研究之一

通过50吨转炉水模实验,研究了顶吹氧量、枪位和喷头结构(十种)对纯顶吹混匀时间的影响,以及底吹气量、凤咀结构(单管式、环缝式和多微孔环管式)、数目和布置(六种)对纯底吹混匀时间的影响,以及不同顶、底吹条件对复吹搅拌混匀时间的影响,探讨了底吹小气量时,顶枪在50吨复吹转炉中的作用和地位及合理操作参数。     

Numerical investigation of the effect of transitory strand opening on mixing in a multistrand tundish

In a multistrand,the outlet near the inlet produces short circuiting flow.This leads to the formation of dead zones inside the tundish,and consequently,the mean residence time decreases.In the present study,numerical investigation of mixing inside a delta shaped tundish with sloping boundaries was carried out by solving the Navier-Stokes equation and employing the standard turbulence model.To decrease the dead zone volume inside the tundish,the effect of closing the outlet near the inlet for a small amount of time and further opening it on the mixing behavior of the tundish was studied.The outlets near the inlet were closed for varying amount of time,and the transient analysis of fluid flow and the tracer dispersion study were carried out to find the mixing parameters of the tundish,namely,mean residence time and the ratio of mixed to dead volume of the tundish.An optimum closure time of the near outlet has been found,which yields best mixing inside the tundish.The numerical code was validated against the experimental observation by performing the tracer dispersion study inside a multistrand tundish and the reasonably good match between the experimental and numerical results in terms of residence time distribution (RTD)curves.The results obtained from the present study confirm the strong role of choosing the right time for opening and closing the outlets to get improved characteristics for the fluid flow and mixing behavior of the tundish.The educational version of computational fluid dynamics(CFD)soft ware PHOENICS was used to solve the governing equations and interpret the results in different forms.     

120 t顶底复吹转炉水力学模拟实验研究

以120 t顶底复吹转炉进行水力学模拟实验,研究单顶吹条件下枪位、顶吹流量对熔池混匀时间、冲击直径和冲击深度的影响;单底吹条件下底吹流量、熔池深度和底部供气元件布置对熔池混匀时间的影响;顶底复吹条件下最佳因素和水平。结果表明:单顶吹时枪位为1 000 mm时混匀时间最短;单底吹时底吹流量为750 Nm3/h时混匀时间最短,底部供气元件布置对混匀时间影响较大;顶底复吹时底吹流量对混匀时间影响最大,而枪位对混匀时间影响最小,当底部布置方式为喷孔在一条直线上对称分布时,顶吹流量为10 000 Nm3/h,底吹流量为600 Nm3/h,顶枪枪位为800 mm,熔池深度为800 mm时,熔池混匀效果最佳。     

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.     

板坯连铸中间包钢液过滤技术水模试验

通过向中间包内吹入惰性气体的水模实验研究，提出了净化钢液的吹气工艺及设备参数，为进一步进行工业性试验提供了理论依据．     

RH真空精炼脱碳速率的物理模拟研究

以某钢厂210 t RH装置为研究对象,利用水力模型对现场生产过程进行物理模拟,研究驱动气体流量、顶吹气体流量、枪位、浸入深度和真空度对脱碳速率的影响。结果表明,随顶吹气体流量的增大,脱碳速率明显增大;随插入管浸入深度的增大,脱碳速率略有增大;随真空度的增大、枪位的减小,脱碳速率逐渐增大;驱动气体流量对脱碳速率的影响很小。真空度为3 616 Pa、枪位为40 mm、插入管浸入深度为125 mm、驱动气体流量为4.0 m3/h和顶吹气体流量为4.8 m3/h时,脱碳速率最大。     

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％.     

钢包底吹氩搅拌混合行为的物理模拟研究

通过物理模拟研究了钢包底吹氩搅拌工艺,测定了混匀时间、液面隆起高度和无渣区直径三个工艺参数,分析了底吹方式和底吹气体流量对钢液流动的影响关系.结果表明,偏心单点底吹的效果好于其他方式.在实验条件下,液面隆起高度主要取决于底吹搅拌的气体流量;底吹气体吹开泡沫渣后产生的钢包表层无渣区直径大小与模拟底吹搅拌气体量、渣层厚度和熔池深度等实验因素有关.     

Modeling study on fluid flow and inclusion motion in 6-strand bloom caster tundishes

The behavior of fluid flow and particle motion in a 6-strand bloom caster tundish was investigated by a water model and numerical simulation. Compared with a device without flow control, the tundish with flow control has an important effect on the fluid flow pattern and inclusion removal. It is revealed that by non-isothermal process, which is real production condition, the fluid flow in tundish shows a strong buoyancy pattern, which drives particles to move upwards. The particle removal was quantitatively studied by mathematical and physical simulations.     

两流非对称中间包内控流装置优化的水模型研究

通过水模型实验和数值模拟,研究了两流非对称中间包采用不同控流装置时流体流动的特性.结果表明：圆形湍流控制器与单挡墙组成的控流装置中间包两出口流体流动差异较大;非对称长方形湍流控制器和多孔挡墙组成控流装置的中间包,两流之间的平均停留时间差异是圆形湍流控制器和单挡墙组成控流装置中间包的2/3,且近长水口侧出口的平均停留时间延长7.5%.     

LF精炼工艺中钢包底吹氩过程数值模拟

精炼过程中进行钢包吹氩是一种去除钢中夹杂，提升其洁净度的重要手段。为快速且低成本地捕获最佳吹氩流量，通过流体分析软件FLUENT对钢包偏心底吹氩过程进行数值模拟。结果表明:在合适的吹气量下，气流会随着吹气时间的延长，在钢液中形成一个闭合的循环区域；吹气量从10 Nm3/h增大到30 Nm3/h，气流的平均动能和平均速度显著增大，死区比例则从21%下降到6%；当吹气量超过临界值30 Nm3/h时，进一步加大吹气量，死区比例趋于稳定，氩气利用率降低；吹气量为30 Nm3/h时达到最佳吹气量，此时钢液中的流体能够获得较大的平均湍动能和平均速度，且钢液中死区比例也达到最小，钢液获得较大的搅拌强度和搅拌区域。     

300t精炼钢包透气砖应用的数学物理模拟

针对300t精炼钢包,在LF设备电极位置与钢包透气砖所在位置的对应关系确定的基础上,通过水模、数模分别采用单吹、复吹时钢包内钢水流动特性和夹杂物去除的对比研究,探讨了透气砖结构性能的影响作用。结果表明,单吹时应使用抗渗透较好且能形成有利于夹杂物去除的气泡形态狭缝式透气砖（PBI）,吹气卷渣临界气量为1．45m^3／h,气量需稳定,混匀时间为82．44s,钢液渗透小,夹杂物去除率为62．86％,能够满足搅拌钢液起到成分和温度的快速均匀以及净化钢液的作用。