Optimization of flow control devices in a tenstrand billet caster tundish

The physical model of a ten-strand billet caster tundish was established to study the effects of various flow control devices on the melt flow. Before and after the optimization of the melt flow, the inclusion removal in the tundish was evaluated by plant trials. The physical modeling results show that when combined with a baffle, the turbulence inhibitor, instead of the impact pad, can significantly improve the melt flow. A turbulence inhibitor with a longer length of inner cavity and without an extending lip at the top of the sidewall seems to be efficient in the improvement of the melt flow. Various types and designs of baffles all influence the flow characteristics significantly. The "V" type baffles are better than the straight baffles for flow control. The "V" type baffle with four inclined holes at the sidewall away from the stopper rods is better in melt flow control than the one with one inclined hole at each sidewall. The combination of a well-designed turbulence inhibitor and an appropriate baffle shows high efficiency on improving the melt flow and an optimal proposal was presented. Plant trials indicate that, compared with the original tundish configuration in prototype, the inclusions reduce by 42% and the inclusion distribution of individual strands is more similar with the optimal one. The optimal tundish configuration effectively improves the melt flow in the ten-strand billet caster tundish.

On numerical modeling of low-head direct chill ingot caster for magnesium alloy AZ31

A comprehensive 3D turbulent CFD study has been carried out to simulate a Low-Head(LH)vertical Direct Chill(DC)rolling ingot caster for the common magnesium alloy AZ31.The model used in this study takes into account the coupled laminar/turbulent melt flow and solidification aspects of the process and is based on the control-volume finite-difference approach.Following the aluminum/magnesium DC casting industrial practices,the LH mold is taken as 30 mm with a hot top of 60 mm.The previously verified in-house code has been modified to model the present casting process.Important quantitative results are obtained for four casting speeds,for three inlet melt pouring temperatures(superheats)and for three metal-mold contact heat transfer coefficients for the steady state operational phase of the caster.The variable cooling water temperatures reported by the industry are considered for the primary and secondary cooling zones during the simulations.Specifically,the temperature and velocity fields,sump depth and sump profiles,mushy region thickness,solid shell thickness at the exit of the mold and axial temperature profiles at the center and at three strategic locations at the surface of the slab are presented and discussed.

Design of a high-precision twin-roll strip caster

During strip casting,the thickness deviation of casting strip directly affects the quality of the hot-rolled sheet because the casting strip needs to be rolled only once.To accurately control the gap between casting rolls and reduce the thickness deviation of the casting strip,a conceptual design of a prestressed twin-roll caster is proposed herein;this caster involves the setting of a constant pressure balancing cylinder between the chocks of two casting rolls.The balancing cylinder hydraulic system adopts a three-way servo valve that controls the hydraulic cylinder.The parameters of the hydraulic power components are determined using the principle of optimal power matching,and the hydraulic system model of the balancing cylinder is thus established.The dynamic analysis and simulation of the hydraulic system are performed using finite element model to obtain relevant evaluation indexes.Finally,the hydraulic system is corrected using proportional-integral-derivative (PID) correction to achieve a well-controlled effect.Thus,the engineering requirements of the strip casting process can be met.

Development of a New Subermerged Entry Nozzle in Thin Slab Caster

The fluid flow in the mould of the thin slab continuous caster has a large intluence on the quality of slabs and its productivity.The fluid flow pattern can be controlled by the SEN (Submerged Entry Nozzle) structure. Traditional SEN can not decrease the surface turbulence and penetration depth at the same time, especially at high casting speed. In order to improve the fluid flow in the mould, a new structure SEN-Dissipation SEN have been invented. The water modeling experiments proved that the dissipation SEN could satisfy, the needs of fluid flow condition in the mould at high casting speed.

Technical improvements of Baosteel EAF bloom caster production line

This paper presents the improvements on equipment and process technologies of Baosteel EAF Bloom Caster Production Line.By using the new VOD equipment,super low carbon super 13Cr was successfully made;By applying and developing the Soft Reduction technology,very good results were achieved on high quality steel grades such as tire cord steel,bear steel,hi-alloy steel;the ladle Anti-Slag Detector is normally applied,based on the detail analysis during the performance test period,the Detector gives out slag entrapment alarms 7-9 s average before slag flows into tundish.By optimizing production control points of each key process,great achievements are realized on high quality steel grades such as tire cord steel,bear steel,hi-alloy steel and hi-S/Al steel,etc.Some achievements and technical indices are presented,too.

The“state of the art”slab caster for stainless steel in ThyssenKrupp Acciai Speciali Terni

On April 23,2009,a new single strand slab caster at ThyssenKrupp Acciai Speciali Terni(TKAST) was successfully started up with the first cast of AISI 304 grade in Terni plant,central Italy.TKAST is the Italian company of ThyssenKrupp Stainless group. The new caster is designed for a total capacity of approx.900.000 tpy of stainless steel slabs covering the complete range of stainless grades,including AISI 300 and 400 families(austenitic,ferritic and martensitic grades).This state of the art caster for the production of 215 mm thick slabs replaced an existing thin slab caster. This paper resumes the reasons of the installation of the new plant designed,manufactured erected and commissioned by Danieli and describes the technological solution,main features as well as the excellent results of this state of the art caster.

Modification of Caster Oil and Study Its Efficiency as Corrosion Inhibitors in Formation Water Media

The present study relates to preparation corrosion inhibiter from caster oil for carbon steel pipeline by two steps;the first step includes sulfonation of caster oil and the second step includes amination the sulfonic caster oil with ammonia solution the final product characterized by FTIR. The effectiveness of the synthesized compounds is studied as corrosion inhibitors for carbon steel;in formation, water was investigated by electrochemical techniques using Tafel plot methods. The synthesized compounds showed enhancement in inhibition efficiencies, and then studied the effect of temperatures on inhibition efficiency.

基于红外相机陷阱技术的蒙新河狸(Caster fiber birulai)活动节律

2013年4—11月,在新疆布尔根河狸自然保护区5个蒙新河狸家族内布设20台远红外相机,共拍摄蒙新河狸有效照片4 991张。采用4种啮齿类动物活动模式指数(日活动强度差异指数α,夜行性指数β,峰值指数γ,活动强度指数θ)分析蒙新河狸不同季节活动节律。结果表明:除4月、11月外,蒙新河狸日活动差异不大;蒙新河狸各时间段夜行性指数β值均高于0.542,表明蒙新河狸属于典型夜行性动物;4—10月,蒙新河狸活动模式呈典型的双峰型,20:00—22:00和次日6:00—8:00有2个明显的活动高峰。11月,由于河狸家族之间栖息地环境不同,水流、水文差异导致河面结冰速度不同,双峰特征也不明显。在布尔根河狸自然保护区,由于河谷林茂密和蒙新河狸的夜行性,用传统方法不易获得蒙新河狸的活动信息,而红外相机陷阱技术较少受到环境条件和研究人员的限制,可为蒙新河狸的长期监测提供有效的技术手段。

全自动激光打标焊牌机器人在方坯连铸机上的应用

智能制造以及无人化现场是钢铁行业产业智能升级的发展方向,某特钢公司新建大方坯连铸机为实现产品质量异常可溯源,实现了高温热铸坯入缓冷坑、热送进加热炉等全流程物流信息跟踪。应用全自动二维码激光打标焊牌机器人,采用激光雕刻金属标识牌,将生产系统铸坯信息打印成二维码标签,工业机器人在高温连铸坯端部焊接标牌,代替人工写号,可靠性高,动作周期短,是国内该类型激光打标焊牌机器人在方坯连铸机上的首次应用,实现了热铸坯标识的物流信息化、自动化、无人化操作。

基于MPC和PID的脚轮式全向移动平台轨迹跟踪

针对现有运动控制策略无法保证独立驱动脚轮式全向移动平台位姿的高精度控制问题,提出一种基于模型预测控制(MPC)和PID控制相结合的双闭环轨迹跟踪控制策略。首先,利用运动学几何关系建立独立驱动脚轮式全向移动平台在世界坐标系下的三自由度运动学模型,基于正交分解法建立平台在机器人坐标系下的逆运动学模型,以反映平台中心点速度与各个脚轮转速间的关系;其次,采用MPC并基于三自由度运动学模型设计位姿控制器,使平台对期望轨迹进行位姿跟踪,并在考虑多目标约束条件的情况下通过位姿控制器求解出最优控制量;最后,采用PID设计速度控制器,用于跟踪位姿控制器输出的期望速度,通过平台逆运动学模型计算得到期望轮速,从而驱动平台实现全向运动。通过仿真验证了所提控制策略的有效性,平台能有效跟踪直线轨迹和圆形轨迹。仿真结果表明,与通过平台转角逆运动学模型解耦驱动轮速的位置单环轨迹跟踪控制策略相比,加入速度内环后系统超调量下降97.23%,响应时间缩短36.84%。

非对称式辊式搅拌在宽板坯连铸机的设计与应用

辊式搅拌是板坯连铸机的核心设备,主要用于提高铸坯等轴晶率,改善铸坯中心疏松和中心偏析,提升铸坯内部质量。对于铸坯宽度大于1 800 mm宽板坯连铸机,采用通辊式辊式搅拌经常出现辊端轴断裂和螺栓松动等故障,导致辊式搅拌使用寿命无法与连铸机正常自由辊相匹配,设备无法连续稳定运转。宽板坯连铸机上采用了非对称式辊式搅拌技术,通过对非对称式辊式搅拌辊进行建模仿真与实际磁学性能测试,验证该类型结构能达到改善铸坯中心质量所需磁场性能要求。通过改造扇形段适配非对称式辊式搅拌的安装,开展了430、0Cr13、439、409、2Cr13等不锈钢钢种的冶金试验,试验结果满足预期铸坯中心质量要求,铸坯中心等轴晶、中心疏松和中心偏析改善效果明显,改造后设备未出现辊端轴断裂和螺栓断裂问题,设备使用稳定性大幅提高,搅拌辊与自由辊寿命基本持平,满足连铸机稳定无故障运行要求。

Numerical Simulation of Electromagnetic Field and Flow Pattern in a Continuous Slab Caster with In-roll Type Strand Electromagnetic Stirring

The electromagnetic field and flow analysis model were developed to simulate the electromagnetic field and the flow pattern in a vertical curved continuous slab caster with the in-roll type strand electromagnetic stirring. The transient electromagnetic field distribution and the induced electromagnetic force were numerically described. The effects of stirring current, stirring frequency, and different stirrer configurations on the electromagnetically driven flow field in the strand were investigated and the optimization of the stirring parameters was discussed by performing a relative comparison of numerical results. Results show that the in-roller type strand electromagnetic stirrer （S- EMS） pair generates the fluctuating magnetic fields, penetrating through the cast slab and periodically parallel shift- ing along the slab wide face w!th time evolution. The transient induced electromagnetic forces travels toward the magnetic flux shifting direction, Different stirring parameters （i. e. current and frequency） and stirrer configurations affect the stirring strength and the flow rbcirculation pattern in the strand, which are closely related to metallurgical performances of the stirrers. There is an optimum frequency to obtain the maximum stirring. The present model pro vides a relatively theoretical insight into the in-roll type strand electromagnetic stirring system for best operating.

异型坯连铸机黏结漏钢的原因分析及控制措施

对异型坯连铸机黏结漏钢的原因进行了分析,导致异型坯黏结的主要原因与保护渣的理化性能、钢种、异常操作、浸入式水口偏斜、钢水温度、结晶器液面波动、结晶器铜板使用寿命等方面有关。在这些方面制定了相关控制措施,有效降低了连铸机黏结漏钢概率。

方坯冶炼超低碳钢中包氧含量控制生产实践

针对方坯生产超低碳钢钢水可浇性差和铸坯皮下气泡问题,对水口堵塞物进行分析,结果表明结瘤产物主要为Al_(2)O_(3)。由于上述问题在中包氧含量低时发生频率较高,同时,依据超低碳钢皮下气泡产生原理,中包氧含量高的钢水在凝固时会产生CO气泡,结合生产经验,得出中包氧含量的稳定控制是解决这两类问题的关键。分析了精炼和连铸过程的钢水、钢渣氧化性对中包氧的影响,采取以下控制措施:熔渣FeO质量分数在10%左右;LF炉离站氧质量分数控制在0.0300%~0.0450%,RH离站氧质量分数控制在0.0008%~0.0015%;缩短静置时间、连铸过程保护浇注;中包氧质量分数控制稳定在0.0025%~0.0045%。通过以上措施,单包连浇炉数提高至5炉,同时铸坯表面皮下气泡问题得到有效控制。

4号板坯连铸机综合性能提高措施

针对4号板坯连铸机经长期运行,设备老化,精度降低,部分功能丧失问题,采取了结晶器调宽改造,扇形段支撑结构调整,扇形段精度提高等措施,使连铸机综合性能得到很大提升,设备精度满足了生产要求,故障率下降,产品质量得到保证。

新型高效喷嘴在八钢板坯连铸机上的应用

八钢一号板坯连铸机自投产以来,喷嘴在线使用异常率居高不下,二冷压缩空气的消耗也较高,对铸坯的质量和产量均产生了影响,导致吨钢成本较高。通过采用新型高效气雾喷嘴、优化二次冷却的配气工艺、强化水气介质的品质管理,喷嘴的在线异常率由原来的25%下降到不到2%,二冷压缩空气的消耗量降低了近30%,连铸坯的纵向、横向的冷却均匀性得到了进一步的提高,连铸坯的缺陷率也大为降低,为炼钢厂整体提质增效、节能降耗提供了保证。

气力输送投饵机发展现状

列举国内外的气力输送投饵机研究成果,介绍了气力输送的影响因素,并列举了CFD-DEM仿真对气力输送投饵机设计的辅助作用,发现CFD-DEM仿真中将颗粒视为离散的实体,采用离散元法(DEM)对颗粒间的相互作用进行描述,采用计算流体力学的方法(CFD)对颗粒-流体的相互作用进行描述。该耦合方法的优点是能够将颗粒的形状、尺寸和密度等因素纳入其中,使其对多相流的数值模拟更为精确。

减少连铸机扇形段异常下线次数的措施与应用

针对连铸机扇形段未到使用寿命异常下线的问题,从其安装过程、使用情况及维修质量三个方面进行分析,得出扇形段精度超差和液压系统故障是连铸机扇形段异常下线的两个主要原因。通过对扇形段二次冷却水喷嘴状态进行监测,加强对扇形段液压系统的维护,规范扇形段维修装配工艺等,有效地减少了扇形段异常下线的次数,保证了连铸机的稳定运行,降低了生产成本。

连铸机-棒材工艺装备的优化

以某钢企炼钢连铸机-轧钢棒材为一体化直接轧制实例,在原有工艺基础上进行了装备及直轧工艺技术改进,将连铸机半径优化为8 m,结晶器长度优化为0.9 m。分析了连铸机新装备工艺参数、钢液浇铸准备时间、作业时间、年度产量、高拉速与二次冷却对钢液凝固的影响。通过采用高拉速结晶器、非正弦电动振动、液压剪剪切、免加热钢坯和轧机前保温辊道罩内等待位排序、钢坯全程保温快速输送等关键工艺技术,实现了钢坯从炼钢连铸机到轧钢棒材第一架轧机108 m全程保温输送。合理利用加热炉出钢炉门及炉内悬臂辊道路径直线输送钢坯到轧机轧制的一种全新直接轧制模式,使技术指标达到国内先进。采用全新直接轧制技术节省了大量煤气,减少了SO2、NOx、粉尘等污染物的排放,做到了绿色、低碳轧制,产生了良好的社会和经济效益,为国内同行起到了示范作用。

一种解耦式主动脚轮全向移动机器人的标定方法

由于机器人的加工制造和装配等因素引起的几何参数误差影响了运动学模型的准确性,因此会同时降低运动控制和里程计精度.为提升全向移动机器人的运动精度,提出了一种针对基于解耦式主动脚轮的全向移动机器人的分步标定方法,该方法通过限制关节空间运动输入来简化运动学矩阵,并利用最小二乘法获得运动学参数的实际值,从而提升运动学模型的精度.搭建了基于解耦式主动脚轮的全向移动机器人实验平台,并通过仿真和实验对标定算法进行验证,实验结果显示在平面内三个自由度上速度控制精度和里程计精度均得到了显著提升,证明了标定算法的有效性.