RH耐火材料浸蚀分析

分析了天津钢管集团股份有限公司100 t RH炉的现状及存在的问题,提出了改进RH耐火材料寿命的具体措施,取得了较好的效果,下部槽和浸渍管寿命最高达到129炉和366炉,降低了炼钢成本,提高了精炼效率。     

RH浸渍管镁铬砖侵蚀分析

分析了影响RH浸渍管镁铬砖侵蚀速率的因素,采取了控制驱动气体流量、制定烘烤火焰标准、改变合金加入方式和提高浸渍管利用率等,使RH浸渍管正常情况下的使用炉次由78炉增加到了86炉,增加了10.25%,有效地降低了炼钢成本。     

RH浸渍管及下部槽使用寿命同步化实践

分析了武钢第一炼钢厂RH浸渍管及下部槽的使用条件、损毁机理和寿命不同步的问题,并从浇注料、型心钢板、烘烤方式、吹氩小管保护、增加风冷装置等几个方面入手,对现用浸渍管及下部槽进行了技术改进。改进后RH浸渍管及下部槽使用寿命明显提高,浸渍管使用寿命由改进前平均36次提高到64.8次,下部槽使用寿命由改进前平均113次提高到136次,并且实现了二者寿命的同步化。     

脱硫剂与RH浸渍管耐火材料作用的热力学分析

RH浸渍管侵蚀严重是目前采用RH脱硫普遍存在的一个问题,弄清其侵蚀机理是减缓和避免侵蚀的基本前提.采用FactSage软件从热力学角度分析了RH脱硫剂与浸渍管浇注料的反应机理,同时分析了脱硫剂以及浇注料中添加MgO组分对侵蚀的影响.计算结果表明,RH脱硫剂与浇注料反应生成的主要相为CaO·6Al2O3(CA6)和CaO...     

250t RH真空精炼炉浸渍管的改进

RH真空精炼炉的主要功能是脱氧、脱碳、净化钢液,是提高钢材质量的基础条件。邯钢250 t RH真空精炼炉投产初期存在的主要问题是浸渍管寿命低（大约30炉）,影响正常的生产,生产成本较高。经过反复分析,认为浸渍管的设计和砌筑存在缺陷,对浸渍管进行改进后,浸渍管的寿命达到90炉以上,保证了生产组织的顺行,为邯钢高级品种钢的上量打下了良好基础。     

RH炉浸渍管使用寿命分析及改进

分析中厚板卷厂RH炉浸渍管使用寿命低的原因,通过优化RH炉浸渍管耐材的理化指标、浸渍管喷补料及喷补工艺,改进顶渣设备及优化烘烤制度等措施的实施,浸渍管平均使用寿命由2007年投产初期的32炉提高到2009年的72炉,RH炉真空钢月生产量由2万吨提高到8.3万吨。     

优化工艺提高RH浸渍管寿命

分析了RH浸渍管寿命较低的原因,采取了优化环砖砌筑、改善浸渍管焊接质量、完善热喷补工艺、优化钢种冶炼工艺等措施,使RH浸渍管的平均寿命大幅提高,由41.3炉次提高到91.6炉次,最高达到122炉次。     

提高真空炉浸渍管使用寿命的应用实践

研究了RH真空炉浸渍管用刚玉尖晶石浇注料的侵蚀机理。熔渣及钢液通过浇注料表面缺陷渗入其内部,与浇注料发生反应生产低熔点变质层,RH炉间歇式的生产特点,耐材温度频繁大幅度波动,因热膨胀系数的差异,在变质层和浇注料之间产生裂纹,在高速的冲刷作用下,造成耐火材料脱落;同时探讨提高硅钢用浸渍管使用寿命的途径。     

优化工艺提高RH炉浸渍管寿命

介绍了迁钢公司针对RH炉浸渍管寿命低的原因,采取了优化环砖砌筑方法、改善浸渍管焊接技术、完善热喷补工艺、优化岗位操作和科学合理的生产组织等措施,使浸渍管的季度平均寿命由41．3炉次提高到91．6炉次,最高达到122炉次。     

单嘴浸渍管RH和弓形浸渍管RH的应用效果

敬业钢铁有限公司现场试验了单嘴浸渍管结构RH炉和弓形浸渍管结构RH炉真空精炼超低碳钢的应用效果,记录两种RH炉提升气体流量和真空度的变化,多次取样检测钢液中w([C])和w([Mn]),分析对比两种RH炉的脱碳效果和混匀时间。结果显示,在真空处理6 min内,两种RH炉的真空度都可降至100 Pa以下,10 min后稳定在50 Pa左右;在真空处理20 min内,前者钢中w([C])基本脱至0.001 0%~0.001 5%,而后者钢中w([C])可以脱至0.000 5%左右,后者的脱碳速率也明显快于前者;前者和后者的混匀时间分别在3和1 min左右。结果表明,后者的冶炼效果明显优于前者,弓形浸渍管比单嘴浸渍管更适用于小吨位RH真空精炼炉。     

Mathematical Simulation of Flow Field for Molten Steel in an 80–ton Single Snorkel Vacuum Refining Furnace

The three–dimensional flow field of molten steel in an 80–ton single snorkel vacuum refining furnace has been mathematically simulated to attain the optimal configuration and operation parameters, such as the bottom blowing Ar flow rate, the eccentric position of bottom blowing Ar port at ladle bottom, the single snorkel inner diameter, and the single snorkel immersion depth into molten steel. The mathematical simulation results show that a stable flow field of molten steel can be achieved in 70–second; meanwhile, the maximal circulation intensity of molten steel in the 80–ton single snorkel vacuum refining furnace can be found on a cross–section with y as 0 mm based on the middle of ladle bottom as circular point of the Cartesian space coordinate under the condition of injecting Ar gas on x coordinate considering the asymmetry of flow field for molten steel in the single snorkel vacuum refining furnace. The recommended parameters of the 80–ton single snorkel vacuum refining furnace with ideal circulation intensity as 970.1 kg/s are the bottom blowing Ar flow rate as 450–500 Nl/min, the eccentric position of bottom blowing Ar port as 250 mm, the single snorkel inner diameter as 1000 mm, and the single snorkel immersion depth as 500 mm.     

单管RH精炼过程钢液流场的水模型实验

采用物理模拟方法对单管 RH 真空精炼过程流场的循环流动、混合特性等进行了研究,建立与 RH 真空精炼装置原型相似比为1∶5的水模型,研究了不同工艺参数对单管 RH 装置内钢液循环流动的影响。对比实验测量数据发现,增大吹氩量和浸渍管插入深度以及浸渍管有效横截面有利于提高循环流量,减小均混时间;在相同的实验条件下,椭圆形浸渍管 RH 比传统浸渍管 RH 的循环流量要大15％以上,单管 RH 的均混时间比传统RH 可以缩短20％;单管 RH 钢包底部吹氩位置位于距钢包中心0.4R(R 是钢包半径)处时,均混时间最短。     

RH真空精炼法浸渍管结构形式的发展

回顾了RH浸渍管结构形式的发展历史。除了简述常规双圆形浸渍管结构外,还介绍了单浸渍管结构、双椭圆形浸渍管结构、多浸渍管结构等3种新型RH结构及其试验研究。比较认为,新结构RH在循环流量、流场、脱碳方面均优于或至少相当于常规RH,但是由于其它新结构的RH结构复杂,只有单浸渍管结构RH已投入工业应用。     

单嘴精炼炉技术的开发与应用

单嘴精炼炉是由我国提出的一种新型真空钢水精炼设备。它具有结构简单、精炼效率高、真空冶炼喷溅少、生产成本低等优点,已经为越来越多的冶金工作者所认识。通过在工业性生产中冶炼轴承钢、超低碳钢和无取向硅钢等品种的实践表明：该炉型在深脱碳、脱硫、脱氧和夹杂物去除等方面表现出了很好的冶金特性,并取得了较为满意的精炼效果。采用物理模拟和数学模型相结合的办法,对单嘴精炼炉的主要操作参数：如吹气流量、吹气位置、浸渍管内径、浸渍管插入深度等工艺参数和流动特性均进行了详细和深入的摸索,所得出的研究结果对实际生产起到了重要的参考和指导作用。随着单嘴精炼炉技术研究的不断深入和完善,这种新型炉外精炼设备必将发挥其自身特点,逐步得到应用和推广。本文也介绍了由日本新日铁提出的REDA精炼炉,它的装备和原理与单嘴精炼炉有一定的相似性,已经被成功应用于超低碳钢及不锈钢的生产。     

Simulation on flow field and mixing phenomenon in RH degasser with ladle bottom blowing

Abstract

A numerical method has been employed to investigate the flow field and mixing characteristic in the Rheinsahl–Heraeus (RH) degasser with side–bottom blowing. The numerical results showed that stream flows in the up snorkel, the vacuum chamber, the down snorkel and the ladle form a large rectangular circulation zone in the RH degasser with side–bottom blowing, which can enhance the circulation flow rate effectively. For an RH with side–bottom blowing, when the included angle of the line between bottom blowing location and ladle centre and the line between two snorkels is zero, the circulation flow rate increases initially with increasing dimensionless distance between the bottom blowing location and the ladle centre and then decreases, while the mixing time increases with increasing dimensionless distance. On the other hand, when the dimensionless distance is 0·2, both the circulation flow rate and the mixing time decrease with the increasing included angle initially, reach their minimum value and then increase. The optimum values for the dimensionless distance and the included angle to achieve large circulation flow rate and small mixing time are 0·2 and π/4 in the present work.     

单嘴精炼炉流场及环流速度的水模型研究

经用水模型实验证明，单嘴精炼炉内钢水循环流动良好．上升和下降流股之间的相互干扰不大。增大气体流量和单嘴内径可显著增大环流量，但单嘴内径对环流速度影响不大。单嘴出口处钢水下降速度约为0.4～0.5m／s，对35t的单嘴精炼炉而言，其钢水环流量约为47～53t／min。     

Mathematical Modelling of Molten Steel Flow Process in a Whole RH Degasser during the Vacuum Circulation Refining Process: Application of the Model and Results

A three‐dimensional mathematical model for the molten steel flow during the RH refining process has been applied to the circulatory flow processes in both a practical RH degasser and its water model unit. The model was presented earlier [1] and one of its characteristics is that ladle, snorkels and vacuum vessel are regarded as a whole. Using this model, the fluid flow field and the gas holdups of liquid phases and others have been computed respectively for a 90 t RH degasser and its water model unit with a 1/5 linear scale. The results show that the mathematical model can properly describe the flow pattern of molten steel during the refining process in an RH degasser. Except in the area close to the liquid's free surface and in the zone between the two snorkels in the ladle, a strong mixing of the molten steel occurs, especially in the vacuum vessel. However, there is a boundary layer between the descending liquid stream from the down‐snorkel and its surrounding liquid, which is a typical liquid‐liquid two‐phase flow, and the molten steel in the ladle is not in a perfect mixing state. The lifting gas blown is ascending mostly near the up‐snorkel wall, which is more obvious under the conditions of a practical RH degasser, and the flow pattern of the bubbles and molten steel in the up‐snorkel is closer to an annular flow. The calculated circulation rates for the water model unit at different lifting gas rates are in good agreement with experimentally determined values.     

RH熔池内弱搅拌区特性的模拟研究

以某钢铁厂170 tRH精炼装置为原型,运用数值模拟的方法对其在不同吹气量、浸渍管内径、插入深度和真空度下的流场进行了模拟,并对熔池内弱搅拌区的分布和变化进行了分析。研究表明:大包熔池上部存在3个弱搅拌区。随着吹气量的增大,1区、3区区域迅速减小;2区先增大后减小,在100 m3/h时达到最大。增大浸渍管内径,1区、2区、3区区域减小,2区在两浸渍管中下方出现了一狭长的弱搅拌区。增大浸渍管插入深度,3个弱搅拌区增大,熔池液面处速度降低,趋于平稳。增大真空度,3个弱搅拌区略有减小。在降低弱搅拌区的几个因素中,吹气量影响最大,浸渍管内径次之,真空度最小。     

Mathematical modelling of molten steel flow in a whole degasser during RH refining process

Abstract

A three-dimensional mathematical model for molten steel flow in a whole degasser during the RH (Ruhrstahl–Heraeus) refining process is proposed. The model has been developed considering the physical characteristics of the process, particularly the behaviour of gas–liquid two phase flow in the up snorkel and the momentum exchange between the two phases. The fluid flow fields and gas holdups of liquid phases, among other parameters, in a 90 t RH degasser and a water model unit of one-fifth linear scale have been computed using this mathematical model. The results show that the flow pattern of molten steel in a whole RH degasser can be well represented by the mathematical model. Apart from the area close to the free surface and the zone between the two snorkels in the ladle, the molten steel in an RH degasser, especially in the vacuum vessel, is reasonably fully mixed during the refining process. However, there is a boundary layer between the descending liquid stream from the down snorkel and the surrounding liquid, which is typical liquid–liquid two phase flow, and the molten steel in the ladle is not perfectly mixed. The blown lifting gas ascends mostly near the up snorkel wall, which is more obvious under the conditions of an actual RH degasser, and the flow pattern of bubbles and molten steel in the up snorkel is closer to annular flow. Calculated circulation rates for the water model unit at various lifting gas rates are in good agreement with values determined by means of water modelling experiments.