四流圆坯中间包的结构优化研究

为净化钢液,提高夹杂物在中间包内的上浮率,通过水模型实验,对4流中间包不同挡墙形式下包内流场及夹杂物去除情况进行了模拟研究.结果表明:现用挡墙控流下的中间包同一侧两流之间的流体流动特性存在很大差异,与内侧相比,外侧流的最短停留时间、峰值时间长、死区体积大,造成中间包内钢液温度不均匀,夹杂物不能有效地上浮去除.改进后的挡墙能很好地解决各流间的同步性,死区比例比原型降低6.65 %,对夹杂物的去除效果增强.工业试验表明,改进后的挡墙在降低总氧和夹杂物方面均优于原挡墙.     

连铸中间包内钢液流动特性分析模型的研究进展

介绍了中间包内钢液流动特性分析模型的研究进展,针对中间包内钢液的去夹杂流动特性,论述了典型的单、多流中间包去夹杂流动特性分析模型,并通过对比分析找出了较优的单、多流中间包去夹杂流动特性分析模型。对于多流中间包内钢液的流动特性,不仅要考虑非金属夹杂物的去除,还要考虑多流中间包内各流流动特性的一致性,对比分析了典型各流流动特性一致性分析模型的特点并找出了合适的分析模型。所找到的合理的去夹杂及各流流动特性一致性分析模型为中间包内钢液流动特性分析提供了理论依据。     

连铸中间包结构优化及夹杂物去除的水模拟研究

以25t中间包为原型,通过实验相似比λ=1:2.3的水模型,分析了4流近似T型中间包3种挡墙形式包内流场及夹杂物去除。结果表明,原挡墙控流下的中间包同一侧两流之间的流体流动特性差异很大,与内侧相比,外侧流的最短停留时间和峰值时间长、死区体积大,造成中间包内钢液温度不均匀,夹杂物不能有效地上浮去除;U-型挡墙能延长峰值时间,但是最短停留时间短,死区比例较大;采用Y-型挡墙可以有效地改变中间包内流场分布,促进夹杂物上浮。30CrMo钢工业试验表明,采用Y-型挡墙钢中大型夹杂物较原用挡墙降低16.9%。     

双流板坯中间包结构优化的数理模拟研究

以国内某钢厂二流中间包为研究对象,为了提高夹杂物在中间包内的上浮去除效果,改善原型中间包的流场特性,利用数理模拟的方法对不同结构的中间包进行钢液流场及温度场的研究,并以此优化出最佳的控流装置。研究结果表明:原型中间包内钢液流场不合理且温度差异明显,采用优化的控流装置后,对于双流浇注时,增加挡坝能够使钢液流动更加活跃,温差也得到减小;对于单流浇注时,改用弯曲水口以及增加挡坝能够很好地改善单流浇注时的流场分布,提高温度的均匀性。     

流钢孔对中间包流体行为影响的数值模拟

以某钢厂双流中间包为基础,建立了相似比为1∶3的物理模型和三维稳态数学模型,研究挡坝控流装置上流钢孔的孔径、数量和倾斜角度等变化因素对中间包内流场的影响。结果表明,孔径大小和流钢孔的倾斜角度对中间包内钢液的流动特性至关重要。在中间包挡坝上开设的流钢孔孔径为120 mm、倾斜角度为15°时,可改变钢液流向,延长钢液流动轨迹,增加夹杂物去除概率,与原型相比,中间包内钢液平均停留时间增加近28 s,死区比例降低46.5%,理论残钢量降低79%。     

中间包内流体流动及夹杂物去除的研究

采用湍流流动的数学模型方法,对板坯中间包内的钢液流动及夹杂物去除率进行了模拟研究。系统分析了在中间包内设置控流设备对钢液流动状态、平均停留时间以及夹杂物颗粒排除率的影响。结果表明,设置挡墙和坝后,中间包内有效防止了短路流,延长了平均停留时间,夹杂物整体排除率明显提高,大大改善了中间包的冶金效果。     

四流T型连铸中间包流场优化研究

以国内某厂所用中间包为研究对象,为了提高夹杂物在中间包内的上浮去除效果,改善原型中间包的流场特性,采用物理模拟和数值模拟的手段对中间包内不同挡墙结构下包内流场和温度场进行模拟研究。结果表明:原型中间包采用的坝对钢液上扬作用不理想,造成包内各流之间差异性大,包内平均死区比例达46. 15%,包内温度分布不均匀,对产品质量影响较大。改进后的挡墙可以明显提高各流之间的一致性,死区比例降低为20. 05%,对包内温度分布也有明显改善。     

薄板坯连铸单流中间包流场的数学模拟

采用数值计算的方法模拟单流中间包内钢液流动行为。计算模拟了无控流装置,应用挡渣墙坝,以及导流隔墙时中间包内钢液流动分布、温度场。结果表明：中间包无控流装置易在中间包中下部形成贯穿流,不利于新旧钢液混合以及夹杂物去除;导流隔墙可使钢液充分上扬,夹杂物易为覆盖渣俘获,有利于夹杂物去除;加装控流装置后,湍动能在到达控流装置前加强,有利于小粒径夹杂聚合上浮;而湍动能在经过控流装置后减弱,有利于钢液平稳流入结晶器;导流隔墙与堰坝组合均可使中间包内钢液充分混合,温度均匀,进出口温差减小。     

板坯中间包内钢液流动特性

通过开展中间包控流装置布置的正交试验,研究了反应器结构对钢水流动行为的影响.着重探讨了不同尺寸中间包的控流装置布置规律及其对钢液流动行为和夹杂物去除的影响,定量化得到了双流板坯中间包控流装置布置与死区体积和结构影响因子D的关系.实验结果分析表明:中间包内部分活塞流体积不利于夹杂物去除,死区体积可准确反映钢液的洁净度水平;出水口抽吸作用对钢液流动行为影响较大,挡坝布置在距出水口1000-1300 mm时钢液流动形态较好,夹杂物聚集导致的水口结瘤率低至7.5%;0.0035相似文献   

中间包结构优化及冶金效果

通过水模型实验,对四流圆坯中间包三种挡墙形式下的包内流场进行模拟研究.结果表明:原挡墙控流下的中间包同一侧两流之间的流体流动特性存在很大差异,与内侧相比,外侧流的最小停留时间、峰值时间长、死区体积大,造成中间包内钢液温度不均匀,夹杂物不能有效地上浮去除.U型挡墙能很好地解决各流间的同步性,但是最小停留时间短,死区比例较大.采用Y型挡墙可以有效地改变中间包内流场分布,促进夹杂物上浮,提高钢水清洁度,为三种挡墙形式之最优.工业试验表明,Y型挡墙在降低铸坯总氧和夹杂物方面均优于原挡墙.     

四流中间包气幕挡墙水模拟研究

采用不同参数的多孔透气砖进行了25 t四流中间包的底部吹气水模拟实验,结合RTD曲线和标准差分析,研究透气砖面积(210～105 mm×56～28 mm) 、4种吹气位置和吹气量(60～120 L/h)对中间包液体流动特性的影响,并与不吹气的情况进行了对比。结果表明,中间包吹气能改善液体的流动特性,均衡其在不同水口间的停留时间,并能延长峰值时间和降低死区体积。透气砖靠近挡墙,采用小气量和小面积更有利于改善现有中间包流场。     

Study on dimension and migration behavior of bubble under annular argon blowing at tundish upper nozzle

The water model experiments were carried out to study the bubble morphology in the tundish and mold with the process of annular argon blowing at tundish upper nozzle. The effects of the position of gas permeable brick, the casting speed and the argon flow rate on the bubble size distribution, the bubble migration behavior and the flow behavior of liquid steel near the liquid level in tundish were further investigated, coupled with the numerical simulation. The results show that with the process of annular argon blowing at tundish upper nozzle, a frustum cone shaped bubble plume can be formed around the stopper rod. The concentration of argon bubbles gradually decreases outward along the radial direction of the stopper rod. Owing to the wall attached effect, the bubble plumes float upward along the stopper rod, which can increase the collision probability between bubbles and the velocity of bubble plumes, causing a larger impact strength on the liquid level in tundish. In addition, a part of small bubbles are wrapped into the nozzle and the mold due to the drag force of liquid steel. With increasing argon flow rate, the number of bubbles in annular bubble plumes and the vertical velocity of liquid steel near the liquid level in tundish increase significantly. With increasing casting speed, the width and the bubble number of annular bubble plumes gradually decrease, leading to a decrease of the vertical velocity of liquid steel near the liquid level in tundish. Increasing the distance between the annular gas permeable brick and the center of tundish upper nozzle, the dispersion of bubbles and the width of bubble plumes increase, and the impact strength of bubbles acting on the liquid level in tundish becomes weaker. As the argon flow rate and the casting speed increase, and the distance between the gas permeable brick and the center of tundish upper nozzle decreases, the gas volume and bubble size in the mold increase. Under the experimental conditions, when the inner and outer diameters of the annular gas permeable brick are 110mm and 140mm, respectively, and the casting speed is 1.2m/min, the appropriate argon flow rate is 4L/min.     

中间包上水口环形吹氩下气泡大小和迁移行为研究

摘要：通过水模型实验研究了上水口环形吹氩工艺下中间包和结晶器内气泡形貌,并结合数值模拟分析了透气砖位置、拉坯速度和吹氩量对中间包和结晶器内气泡尺寸、气泡迁移和中间包近液面钢液流动的影响。结果表明：上水口环形吹氩形成以塞棒为中心的圆台状气泡羽流,气泡浓度沿径向向外逐渐减少;附壁效应使得气泡羽流偏向塞棒壁面流动,增大气泡的碰撞聚并概率和近塞棒壁面的羽流上升速度,对中间包液面产生较大冲击作用;同时,部分细小气泡会随钢液进入水口及结晶器内部;增大吹氩量,中间包内环形气泡羽流中气泡数目明显增多,中间包近液面钢液上升速度增大;增大拉坯速度,环形气泡羽流的宽度和气泡数量逐渐减小,近液面速度减小;增大透气环距水口中心距离,中间包内气泡弥散度增大,环形气泡羽流宽度也随之增大,气泡羽流对中间包液面冲击作用减弱;增大吹氩量和拉坯速度、减小透气环距水口中心距离,进入结晶器的气量和气泡尺寸逐渐增大。实验条件下,透气环内外径为110mm/140mm、拉坯速度为1.2m/min时,吹氩量为4L/min较为合适。     

上水口环形吹氩对中间包内渣眼形成的影响

 中间包上水口环形吹氩可以在塞棒周围形成清洗钢液的环形气幕,同时部分氩气泡随钢液进入上水口内,可以减少非金属夹杂物在水口内壁的黏附,起到防止水口堵塞的作用。然而,不合理的吹氩量会导致中间包内液面渣层受过强的气液羽流冲击而形成渣眼,使得钢液裸露并发生二次氧化,严重影响铸坯质量。采用标准 k ε 湍流模型研究中间包内流体流动,采用DPM模型和VOF模型耦合方法,研究上水口环形吹氩条件下渣眼的形成及演化规律。结果表明,上水口环形吹氩在塞棒周围形成较强的上升流,塞棒上部邻近区域存在多个涡流区;在钢液涡流的影响下,中间包液渣下层远离塞棒区域,上层向塞棒区域迁移;随着吹氩量的增大,平均湍动能增大,塞棒附近钢液速度逐渐增大,钢渣界面钢液速度先增大后减小,渣眼边缘钢液速度先增大后减小然后再增大,速度与垂直方向夹角逐渐减小;增大吹氩量,中间包熔池液面形成以塞棒为中心的渣眼,渣眼面积逐渐增大。试验条件下不产生渣眼的临界吹氩量为4.2 L/min,对应的钢渣界面最大速度为0.247 m/s,与垂直方向夹角为70°。     

精炼时利用小气泡搅拌去除钢液中的氢和夹杂物

通过理论计算研究和分析了钢液气泡直径、吹气量和吹气时间对精炼时去氢和夹杂的影响。氩气经透气砖进入钢液后会形成大量的气泡,小气泡在钢液中能有效地增大脱气面积,有利于减小钢液中的氢含量。夹杂物与气泡的粘附上浮是钢液中去除夹杂物的一种有效方式,气泡越小、夹杂物越大,夹杂物就越容易去除。在钢包精炼过程中,应使用小气泡来达到较好的去氢和去夹杂效果,气泡的最优直径为1～3 mm。     

Flotation of nonmetallic inclusions during argon injection into the tundish of a continuous-casting machine. Part 1

The basic factors affecting the removal of nonmetallic inclusions from liquid steel when inert gas is injected into the tundish are analyzed. On that basis, optimal injector parameters when using an annular injection lance are established—specifically, the gas flow rate and the diameter of the argon bubbles at breakaway from the pore that ensure the maximum removal of inclusions.     

中间包夹杂物的去除与控制新技术

通过对中间包中不同去除夹杂物的手段进行综合分析，得到各环节中间包均应保护浇注和防止卷渣卷气，中间包应具有合理的控流装置（上下挡墙、湍流抑制器、旋涡抑制器）以得到理想的流场；利用钢包注流生成的小气泡、中间包气幕挡墙和电磁搅拌离心流动可以有效去除中间包内钢水中夹杂物；连续真空处理对脱气和去除夹杂物有良好效果但其可调性差，电磁过滤可作为辅助方法去除夹杂物。     

Bubble and liquid flow characteristics during horizontal cold gas injection into a water bath

In refining processes such as the AOD process cold gas is blown horizontally into the molten metal bath of the processes. The spatial distribution of bubbles in the bath is one of the important factors influencing the efficiency of the processes. In this study, a water model study was carried out to understand the characteristics of bubbles and liquid flow generated by horizontal gas injection. The bubble and liquid flow characteristics were measured using an electro‐resistivity probe and a laser Doppler velocimeter, respectively. In the flow field near the nozzle the bubble characteristics for the horizontal cold gas injection can be predicted by empirical equations derived for isothermal gas injection systems. The liquid flow characteristics could not be measured in this region. On the other hand, in the region far from the nozzle the two characteristics for the cold gas injection became different from those for the isothermal gas injection because of enhanced buoyancy force acting on expanding cold bubbles due to heat transfer.     

钢中夹杂物去除技术的进展

钢中夹杂物去除的主要环节为夹杂物的长大、上浮和分离。钢中夹杂物去除技术的主要进展有:气体搅拌-钢包吹氩、中间包气幕挡墙和RH-NK-RERM法;电磁净化-钢包电磁搅拌、中间包离心分离和结晶器电磁制动;渣洗技术;过滤器技术。文中分析了各种夹杂物去除技术的冶金功能,将不同夹杂物去除技术进行合理组合,实现多功能精炼,可取得最佳冶金效果。     

Hydraulics and Mathematics Simulation on the Weir and Gas Curtain in Tundish of Ultrathick Slab Continuous Casting

The molten steel flow pattern in continuous casting tundish could be improved if the flow control devices were properly used. With reasonable application of weir and air curtain, the disturbance at injection zone of the tundish was reduced. The flow path of the molten steel was changed, and the short-circuit flow was eliminated. Therefore, the residence time was lengthened. An air curtain with bubbles floating could promote the surface flow and improve inclusions removal. The application of weir and air curtain in an ultrathick slab continuous casting tundish was investigated with hydraulics and mathematics simulation. The residence time and dead volume fraction were studied through orthogonal experiments with different positions of the flow control devices. The efficiency of three factors was analyzed, and the optimum positions of the weir and air curtain were obtained. Besides, the discrete phase model was suitable for simulation of the interaction between gas bubbles and molten steel, and the mathematics results shown the optimum one got larger inclusion flotation rate.