连铸中间包异钢种连浇生产实践

针对连铸大圆坯生产线生产的特殊钢种类多以及多为小批量生产的特点,为了减少连铸慢换中间包次数和热停工时间,在连铸中间包进行异钢种混浇生产试验,探索混浇生产过程中浇铸顺序、不同拉速、中间包钢液液位等控制方式对铸坯混浇区域长度的影响,为判定混浇坯长度提供可靠的数据支撑.通过对不同试验混浇坯成分的分析比对,结果表明:连铸坯中心...     

异钢种混浇生产实践

根据鞍钢股份有限公司鲅鱼圈钢铁分公司异钢种混浇的实际情况,通过分析钢水成分变化规律,确定了混浇坯长度划定方法,优化了异钢种混浇的中间包钢水量、中间包钢水温度、铸机拉速、更换结晶器保护渣等工艺参数,采取措施后,实现了异钢种混浇的稳定生产,连铸机单中间包混浇罐数由9.3罐提高至9.6罐,节约生产成本0.26元/t。     

宝钢二连铸异钢种连浇的水模实验研究

针对宝钢二连铸的异钢种连浇进行了水模实验,研究了非稳态条件下中间包剩余钢水量、铸坯断面尺寸、拉速等因素对异钢种连浇时混合率的影响.在水模实验和现场试验的基础上,建立了异钢种连浇铸坯成分预测模型,该模型可以对不同工艺条件下异钢种连浇过程中铸坯成分的变化情况进行预测,从而为确定交接部铸坯的起始位置和长度提供依据.     

异钢种连浇工艺参数对交接坯长度的影响

通过1∶3水力学模型,对重钢板坯异钢种连浇过程进行水力学模拟,研究不同拉速、中间包余钢量和浇铸顺序条件下沿铸坯长度方向的无量纲浓度变化曲线。结果表明,增大通钢量、降低余钢量和先浇铸元素成分浓度低的钢都会减少交接坯长度,但中间包余钢量比其他两个因素对交接坯长度有更显著的影响。     

连铸坯异钢种混浇的探索

以济钢连铸混浇坯为研究对象,通过对大量实验数据进行分析和对比,摸索出碳、锰和微合金元素等主要成分在60t中间包异钢中混浇过程中的变化规律,为异钢种混浇坯的判定提供了可靠的理论依据及实践指导。     

薄板坯单流中间包混浇水力学模型试验研究

针对武汉钢铁有限公司CSP高品质钢品种多、批量小、生产组织复杂、连铸成本高的难题,采用水力模型方法对CSP 45 t单流连铸中间包异钢种混浇进行了研究,模型与实物比例为1︰2,试验满足弗劳德准数相似。分析了不同拉速和中间包余钢量条件下,铸坯长度方向上浓度曲线的变化,提出了较优组合方案,并进行了现场试验。试验结果表明:在中包剩余钢水量10 t、拉速4.5 m/min时,混浇坯长度最短,为22.40 m,其结果与现场试验结果相符。项目技术应用后,缓解了高品质钢多品种、小批量生产组织复杂的难题,提高了薄板坯连铸高品质钢的生产效率,降低了制造成本。     

同中包异钢种混浇模型在梅钢的应用

通过钢级、出钢记号、成分范围、产品最终用途制定了同中包异钢种混浇应用技术规范。在L4质量混浇坯出钢模型中,将现有的出钢记号通过混浇坯出钢记号表和混浇坯索引组关系表实现了出钢记号混浇管理。在炼钢L3中,根据精炼实际成分指导连铸混浇操作,并根据实际连铸混浇操作情况实现了混浇板坯的系统判定。     

连铸连浇混浇坯的过渡时间及影响因素

针对试验情况，对连铸连浇时混浇坯的形成和影响因素进行了分析。分析认为，不同钢种连浇时中间包内钢水和铸坯的化学成分初期变化很快，后期逐渐减缓向连浇炉（罐）的化学成分过渡，且边流滞后于中间流，滞后时间１．５￣２ｍｉｎ。过渡时间及混浇坯量受中间包形状和结构及残留钢水量、成分差值和质量流速等的影响。     

连铸异钢种连浇过渡坯模型的研究

以舞钢炼钢厂连铸坯异钢种连浇过渡坯为研究对象,通过数学模型和试验模型的验证,以两炉异钢种成分相差最大的化学元素为依据,来精确控制过渡坯长度,减少金属损耗,提高钢水收得率,实现降本增效。     

连铸混浇坯的过度时间及影响因素

为提高连铸比实现全连铸，鞍钢二炼钢在小方坯连浇不同钢种过渡段铸坯成分差异上做了试验研究，并指出小方坯连铸机增设钢水快速分析和快速节装置的必要性。     

Intermixing model of continuous casting during a grade transition

To investigate the composition distribution that develops in continuously cast steel during a grade change, an efficient, accurate, and user-friendly computational model has been developed. The model is fully transient and consists of three submodels, which account for mixing in the tundish, mixing in the liquid core of the strand, and solidification. The first submodel of mixing in the tundish consists of two plug flow zones, two back-mixing boxes, and two dead volumes. The second submodel solves a one-dimensional (1-D) diffusion equation in series with two back-mixing boxes to calculate concentration histories in the strand, and the third submodel transforms these histories into slab compositions. The model was calibrated using both concentration histories measured on tundish water models and calculations from a three-dimensional (3-D) model. It was then verified with several sets of composition measurements along the surface and centerlines of slabs. The model is capable of tracking mixing phenomena for arbitrary tundish filling and casting speed histories. It has been used to compare the effects of different grade change procedures on the amount of intermixed steel, including standard sequence casting, flying tundish change, and insertion of grade separators. Mixing in the strand was found to be very important. Without a grade separator, a flying tundish change had very little benefit on reduced intermixing, for the typical conditions considered.     

宝钢一连铸不同钢种连浇的水模实验研究

针对宝钢一连铸60t中间包进行了1:3水模实验,主要研究了非稳态条件下拉速、余钢量对不同钢种连浇时交接部长度的影响,以利于改进现场的操作.     

中间包钢水连续测温技术在韶钢的应用

介绍了韶关钢铁集团有限公司第三炼钢厂2号板坯连铸机采用连续测温技术进行中间包钢水测温,该技术能实现中间包钢水的连续测温,为连铸生产过程拉速控制提供了温度检测保证,是取代现行钢水间断式测温的好方法.     

攀钢连铸高效化技术

介绍了高效连铸以及相关技术在攀钢的应用及效果。通过对钢包精炼的改进和中间包冶金技术的优化,提高了钢水洁净度;结合复合辊、低过热度浇注技术的采用和二冷技术与高速连铸保护渣的研制等新技术、新工艺的研究与应用,全面改善了高拉速条件下的铸坯质量,使攀钢板坯连铸机的铸坯产量、质量以及铸机作业率均有较大的提高。     

Mixing and Oxide Cleanness in Sequence Casting of Heats of Differing Compositions

For a two‐strand slab caster and a tundish capacity of 50 t the transition zone between two heats of different chemical composition was experimentally defined. The distribution of various elements was measured. The transition curves also show the penetration depth of the casting stream using a bifurcated submerged nozzle. This is basic information for the calculation of the mixing zone. Knowledge of the permissible composition ranges permits optimisation of the usable length of the strand. The impact of ladle change on oxide cleanness is analysed as well.     

Modeling of steel grade transition in continuous slab casting processes

Mathematical models have been developed and applied to investigate the composition distributions that arise during steel grade changes in the continuous slab casting processes. Three-dimensional (3-D) turbulent flow and transient mixing phenomena in the mold and the strand were calculated under conditions corresponding to a sudden change in grade. The composition distribution in the final slab was then predicted. Reasonable agreement was obtained between predicted and experimental concentration profiles in the slab centerlines. Intermixing in the center extends many meters below the transition point, while intermixing at the surface extends above. Higher casting speed increases the extent of intermixing. Mold width, ramping of casting speed, and nozzle design have only small effects. Slab thickness, however, significantly influences the intermixing length of the slab. The axial transport of solute due to turbulent eddy motion was found to be many orders of magnitude greater than molecular diffusion and thus dominates the resulting composition distribution. Different elements, therefore, exhibited the same mixing behavior under the same casting conditions, despite having different molecular properties. Numerical diffusion caused by the finite difference schemes was investigated and confirmed to be much less important than turbulent diffusion. In the lower portion of the strand (lower than 3 m below the meniscus), the convection and diffusion can be reasonably approximated as one-dimensional (1-D) axial flow.     

基于模式识别和人工神经网络建立的板坯连铸二冷水模型

介绍了一个种铸坯表面测温的方法,并依据铸坯表面温度,应用模式识别与人工神经网络相结合的方法,建立了板坯连铸的二冷水模型。该模型既可根据模式识别的分类图预报优化的二次工艺参数,亦可根据钢种、中间包钢水温度、拉速及希望的二次区不同部位的铸坯表面温度由LS顾的输入神经元网络,预测报连铸不同回路的水量。该模型运用于生产实际后,铸坯表面裂纹大为减少,取得了较好的效果。     

Physical modelling investigation of influence of strand blockage on RTD characteristics in a multistrand tundish

Abstract

In the continuous casting process, the tundish acts as a continuous molten steel distribution vessel. The importance of the tundish during the molten steel delivery becomes more significant when it supplies liquid steel to more than one mould. In the present work, a water model of a six strand billet caster tundish has been used to study the effect of strand blockage on the residence time distribution (RTD) characteristics at the strands. All the experiments were performed under steady state conditions. Potassium chloride was used as a tracer for the study. The effects of blockage on the strand dissimilarity among the open strands were also studied. Both single and dual strand blockage experiments were performed. Blockage of strands deteriorated the RTD characteristics at the open strands. The results reveal the most preferred options for strand blockage when the plant operation needs to do so.     

十二流小方坯中间包优化及冶金效果

利用数值模拟对宣钢十二机十二流连铸机中间包的三维流场、浓度场和温度场进行研究,优化出了最佳控流装置。应用结果显示,采用优化结构后的中间包,流场明显改善,各流的流动特性趋于一致,高温钢液对第6流塞棒的冲击减轻,各流最大温差由优化前的10 K降低为优化后的4 K。且连浇时间由优化前的20 h延长到26 h。     

鞍钢板坯连铸机中间包挡墙设置优化与改进

采用数学模型方法研究了连铸中间包过程的钢水流动，混合以及停留状况，并以提高钢水平均停留时间为依据优化了鞍钢第三炼钢厂板坯连铸中间包的挡墙设置，通过对中间包过程钢水夹杂物运动行为的数学模化和仿真计算探讨了夹杂物的碰撞长大。上浮排除以及被耐火材料墙壁粘结吸附等现象。在实际生产中对有关研究结果进行了验证分析。