宽板坯结晶器浸入式水口结构优化的数值模拟

以某钢厂宽板坯连铸结晶器为研究对象,利用商业软件PHOENICS建立一个三维有限差分模型,模拟宽板坯连铸结晶器内钢液的流动分布.通过分析水口底型、倾角、插入深度等工艺参数对钢液面波动、流股对结晶器窄面的冲击力及涡心高度的影响,得出适用于宽规格结晶器的合理的浸入式水口.通过研究,为优化宽板坯结晶器内钢液的流场及浸入式水口的设计提供了科学依据.     

宽板坯连铸结晶器浸入式水口结构优化的研究

针对宽板坯连铸生产现状,采用商业软件PHOENICS对其建立三维数值模型,模拟宽板坯连铸结晶内钢液的流场分布.研究了不同水口倾角、插入深度及拉速等参数条件对结晶器内流场的影响,得出了适用于宽规格结晶器合理的浸入式水口.这为优化宽板坯结晶器内钢液的流场及浸入式水口结构及确定合理的工艺参数提供了科学依据.     

板坯连铸结晶器内液面波动的水模型研究

以某厂板坯连铸结晶器为原型,采用1:1的水模型进行试验,以瞬时波高为判断依据,研究了拉速、浸入式水口出口角度、水口浸入深度、水口底面结构等工艺参数对板坯结晶器内流场和液面波动行为的影响.提出了优化结晶器流场的工艺参数,为在实际生产中减少结晶器内卷渣提供了依据.结果表明:拉速对板坯连铸结晶器内液面波动的影响最大,水口倾角...     

SEN壁厚对结晶器内钢液流场和温度场的影响

针对板坯连铸结晶器,利用PHOENICS软件,计算结晶器内流体的三维流场和温度场,比较和分析了浸入式水口壁厚对结晶器内流场和温度场的影响,为优化浸入式水口结构参数提供参考。     

攀钢板坯连铸结晶器内流场的水力学模拟研究

采用水力学模拟方法研究攀钢板坯连铸结晶器内流场,分析浸入式水口结构尺寸、塞棒吹Ａｒ量和拉速等工艺参数对连铸结晶器内钢液流动状况的影响,在此基础上优选出适合攀钢板坯连铸工艺的浸入工水口结构尺寸及相关参数。     

厚板坯连铸结晶器流场数值模拟

针对鞍钢新轧钢第一炼钢厂厚板坯连铸结晶器建立了三维湍流数学模型和三维实体模型.应用有限元软件对厚板坯连铸结晶器内的流场进行了模拟,计算了铸机拉速、浸入式水口出口倾角和水口浸入深度等工艺参数对结晶器内钢液流动的影响.对比表明,数值模拟结果与水模实验结果相符.     

一键式浸入式水口更换系统在首钢京唐连铸机的应用

炼钢连铸生产中结晶器浸入式水口在线更换时,人工方式操作存在作业环境差、操作繁琐、难以保证结晶器液位稳定等问题,为此,在首钢京唐钢铁联合有限责任公司连铸机项目中设计并投用了一键式浸入式水口更换系统,以实现根据计算板坯长度,准确判定合适的水口更换时机并自动完成更换的功能,同时通过适当调节结晶器液位和板坯拉速,最大限度降低液位波动,保证了连铸生产的稳定和成品质量。     

梅钢连铸板坯边裂的成因与对策

通过对梅钢炼钢厂连铸机板坯边裂的现场调查、测试和统计,分析了板坯边裂的成因,并提出了相应的对策,指出结晶器足辊变形、结晶器倒锥度不合适、结晶器内钢水偏流、结晶器角缝挂钢、浸入式水口参数及吹氩操作等是产生连铸板坯边裂的主要原因。     

连铸板坯边裂的原因分析及预防措施

通过对梅钢炼钢厂1号连铸机板坯边裂的现场调查、测试和统计,分析了板坯边裂的产生原因,并提出了相应的预防措施,指出结晶器足辊变形、结晶器倒锥度不合适、结晶器内钢水偏流、结晶器角缝挂钢、浸入式水口参数及吹氩操作等是产生连铸板坯边裂的主要原因。     

连铸浸入式水口中的钢水流动特性

连铸结晶器中钢水流动的控制会直接影响板坯和产品的表面和内部质量。虽然结晶器中的钢水来源于浸入式水口,但着眼于浸入式水口中液流方面的研究却很少。本研究借助于液态合金模型与钢流模型,通过透明的浸入式水口现场观察了浸入式水口中的钢水流动情况。随后又在工业连铸机上测量了结晶器弯月面处排出的氩气。在液态合金模型试验中,势流和活塞流的形成取决于氩气流量、金属流量以及水口直径。减少氩气流量、增加金属流量以及缩小水口直径都会导致水口中弯月面高度的升高。通过透明的石英玻璃水口观察钢流。势流与活塞流的出现也都取决于氩气流量。根据从结晶器弯月面处测量的氩气净流量,发现从上滑板中吹入的氩气有20％左右被带入水口中。根据这些试验结果可以得出以下结论：在平常操作过程中,传统板坯连铸机的浸入式水口内充满钢水,钢流类似活塞流。     

Slab quality improvement by controlling mould fluid flow

Abstract

Cleanliness of steel is a primary requirement for flat products. It is obtained with minimum of defects by controlling the liquid flow characteristics in the mould and fluctuations over the meniscus surface. Liquid flow in the mould region is due to the momentum of the pouring stream which in turn is related to the clogging of submerged entry nozzle and argon flow in the mould. This makes control of liquid steel flow dynamics in the mould important. The mould level fluctuation index, flow fraction or clogging percentage and optimised gas flow models have been developed and are correlated for minimised surface fluctuations throughout the casting sequence. Tundish weight, casting speed, casting section and immersion depth of the nozzle which primarily change the flow profile inside the mould are the key operational variables considered for model calculations. The operational parameters were adjusted to follow the developed models criteria for different casting conditions. Online application of these operational control models contributed to stabilise the mould fluid flow and have helped in decision making for pumping, flushing and tube changing. The present paper describes the mathematical approach adopted in calculation of optimum casting parameters for controlling flow of liquid steel, nozzle clogging and gas injection rate at JSW Steel Ltd. This has resulted in considerable reduction in mould level fluctuations and production of superior quality slabs even at higher casting speeds.     

Three-dimensional analysis of molten steel flow in slab continuous casting mould with rotated ports in submerged entry nozzle

Abstract

The purpose of this study is to develop a three-dimensional (3D) analysis system capable of analysing the flow field of molten steel in the slab continuous casting mould with rotated ports in the submerged entry nozzle. The ultimate goal is to obtain the optimal design for the entry ports of the submerged nozzle, which can introduce favourable flow patterns to remove non-metallic inclusions and avoid entrapment of molten slag and casting powder to produce steel slab of high cleanliness. In this study, a computational fluid dynamics technique, Sola-Surf, is employed to conduct the 3D fluid flow analysis. The technique has the capability of treating fluid flow problems with a free surface that slightly vibrates. The slightly vibrating free surface presents fairly accurately the behaviour of the molten slag–casting powder layer in the continuous casting mould. The developed simulation system is then tested on a slab continuous casting mould to analyse the fluid flow behaviour of molten steel under various nozzle designs. The design conditions include submerged depth of the nozzle, tilted angle of the nozzle port, and rotated angle of the nozzle port. The results of the simulations show that of the various design factors rotation of the nozzle entry ports has the greatest effect on the flow pattern. It can prolong the residence time of the molten steel and stabilise the molten slag–casting powder layer, which is very favourable for obtaining continuous casting slag of high cleanliness.     

板坯连铸结晶器内吹入气体对钢液行为的影响

采用水力学模拟方法研究板坯连铸结晶器内流场，分析塞棒吹Ａｒ时，浸入式水口琢拉速等工艺参数对连铸结晶器内钢液行为的影响。     

连铸板坯表面纵裂的成因分析及改进措施

对连铸板坯表面纵裂的进行了一系列的分析研究，查明浸入式水口在注中损坯和结晶器用保护渣的性能不合是主要原因，采用相 应的改进措施后，该类缺陷的发生率大幅度降低。     

舞钢连铸坯表面纵裂产生原因初探

主要分析了舞钢连铸板坯表面纵裂纹产生的原因,同时从稳定拉速、控制结晶器冷却、二冷水弱冷、浸入式水口优化、保护渣的使用和首炉纵裂控制等方面着手,制定相应的预防措施,最终减少了连铸坯表面纵裂纹的发生几率.     

连铸用浸入式水口(SEN)的发展

浸入式水口是连铸用关键功能耐火材料之一,其使用效果直接影响连铸效率和铸坯质量.随着连铸技术的发展,浸入式水口也经历了不同的发展阶段.本文介绍了浸入式水口在连铸中的位置及其作用,着重介绍了不同时期不同材质浸入式水口的优缺点和几种具有防堵功能的浸入式水口,并对浸入式水口的发展趋势进行了分析.     

板坯连铸结晶器电磁制动技术及其应用

叙述了板坯连铸结晶器中应用电磁制动技术的发展、研究状况。电磁制动技术可以控制结晶器内钢液的流动，减少结晶器保护渣的卷渣，有利于结晶器内夹杂物的去除，从而提高铸坯质量，并有利于提高铸坯拉速。研究结果表明电磁制动特性取决于板坯宽度、浇铸速度、氩气流速和浸入式水口(SEN)形状等浇铸参数，介绍了各种浇铸参数对电磁制动效果的影响。     

F-free mould powders for low carbon steel slab casting – technological parameters and industrial trials

The choice of the mould powder for slab casting is a difficult task because mould powders have many important functions during the continuous casting of steel. CaF₂ is a key ingredient in conventional mould slags since it reduces the viscosity, the liquidus temperature and the break temperature. Fluorine in mould powders is undesirable from the environmental and health points of view due to the following reasons: (i) evolves easily from slags, producing health-injurious gaseous substances, such as hydrofluoric acid; (ii) creates problems for storage and utilisation of solid waste and (iii) causes machinery corrosion. Aim of the present work is to describe the development of a new F-free mould powder for low carbon steel slab casting replacing CaF₂ with B₂O₃. Laboratory tests and industrial trials were performed considering the technological parameters viscosity, break temperature and crystallisation tendency. From laboratory tests it was concluded that important technological parameters are similar when comparing the F-bearing mould powder (reference) and the new F-free B-bearing mould powder for low carbon steel slab casting: viscosity at 1300°C, break temperature, and crystallisation tendency. It was observed during industrial trials that a significant decrease of the submerged entry nozzle erosion was observed. The results were similar when comparing the F-bearing and the F-free performance: slag pool thickness measurements, melting behaviour, Al₂O₃ absorption, mould powder consumption and slabs superficial quality.     

板坯连铸提高拉速工艺研究与实践

对首钢第二炼钢厂板坯铸机提高拉速的工艺进行了研究，为适应1．2～1．3m／min拉速条件下稳定正常的生产，对结晶器冷却水量、浸入式水口参数、二冷比水量、振动参数、保护渣性能指标进行了调整。通过采取以上措施，板坯月产量达到了9．5万t的水平，达到了双流铸机的产量水平。     

IF钢冷轧板表面条状缺陷成因及控制

条状缺陷是IF钢冷轧板常见的表面缺陷之一,针对邯钢IF钢冷轧板表面出现的条状缺陷,分析了该类条状缺陷的成因,并提出了合理的控制措施。通过SEM-EDS分析发现条状缺陷内部存在大量的小尺寸Al_2O_3颗粒,分析其来源于铸坯中大型Al_2O_3夹杂物。对不同浇注阶段铸坯进行SLIME法大样电解并采用SEM-EDS分析其大型夹杂物类型,发现在交接坯和换水口坯中存在较多的大型Al_2O_3夹杂物,分析其来源为水口结瘤物。综合分析后得出此类条状缺陷成因是水口结瘤物脱落被卷入结晶器,并在铸坯中形成大型Al_2O_3夹杂物,进而在冷轧板轧制过程中形成表面条状缺陷。