浅析酒钢4#、5#连铸机引锭杆窜动的原因

引锭杆是现代化高效连铸机开浇牵引设备,引锭杆窜动容易引发开浇漏钢等事故发生,本文论证分析了酒钢4#、5#板坯连铸机开浇过程中引锭杆窜动的原因,以及相应的解决方案.     

电磁制动技术在板坯连铸过程中的应用

考察了结晶器电磁制动技术在板坯连铸过程中的应用效果,比较了电磁制动对结晶器内钢液火焰状态和温度分布的影响,结果表明：合理的制动电流可使结晶器内钢液液面波动降低、火焰均匀分布,燃烧状态达到最佳,过大和过小都不利于火焰燃烧状态和传热的均匀性;施加电磁制动可显著提高结晶器内钢液温度分布的均匀性,平均温差由10℃降低到4℃;合理使用电磁制动有利于提高保护渣渣耗且使保护渣熔化更均匀,本研究条件下的吨钢渣耗提高了0.021kg;铸坯质量检验表明,使用电磁制动可降低铸坯中氧化夹杂物含量,对于试验条件下的低碳钢全氧质量分数降低了49%。     

马钢大圆坯连铸机引锭杆下滑现象的研究与控制

结合马钢特钢公司大圆坯连铸机生产中多次发生刚开浇时引锭杆突然下滑的现象,综合研究了导致引锭杆下滑的各种可能因素,并从增加设备精度、设备进行预防性维护、操作标准化,设备动作过程优化等方面采取了相应的应对措施,有效地降低了大圆坯连铸机发生开浇引锭杆下滑的几率,减少了开浇漏钢损失。     

结晶器钢液电磁控制技术的发展

论述结晶器内钢液流动的特征及流动控制的目的,介绍并分析了电磁搅动电磁制动、软接触电磁连铸等结晶器内钢液流动电磁控制技术的特点及发展趋势.     

稳定连铸机生产的新型挠性引锭杆

据“Steel Times”1992,No.1报道,连铸机启动操纵杆常常称为引锭杆是其开始启动的主要设备,引锭杆常用于连铸的开浇过程中,它从连铸结晶器一直延伸到拉矫机,从根本上说,引锭杆的作用有三:     

宽度对CSP漏斗形结晶器电磁制动效果影响的数值模拟

 铸坯尺寸是影响电磁制动效果的重要因素。以某钢厂薄板坯CSP漏斗形结晶器为研究对象,建立了描述CSP漏斗形结晶器电磁制动的三维数学模型,研究宽度对电磁制动效果的影响。研究表明：3种铸坯宽度下,电磁制动均可使涡心位置上移并降低下部漩涡范围;电磁制动可降低自由液面水平方向流速,抑制弯月面波动,提高弯月面温度;在结晶器出口处,使用电磁制动可使铸坯宽面坯壳厚度更均匀并提高窄边凝固坯壳厚度;随铸坯宽度增加,电磁制动效果变得不明显。     

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。     

电磁制动对CSP漏斗型结晶器流场和液面波动的影响

针对铸坯断面为1 500 mm×90 mm的漏斗型结晶器,在拉速为5 m/min的条件下,通过耦合湍流模型、多相流模型以及电磁制动模型,计算了电磁场作用下结晶器内流体流动与液面波动特征.数值模拟结果表明,应用电磁制动能显著改变结晶器内钢液流动行为,使结晶器内流场分布更加均匀.此外,当施加的磁场强度为0.2和0.3T时,结晶器最大液面波动高度从未施加电磁制动时的15mm减小至9.2mm和2.33 mm.综合考虑到电磁制动效果与生产成本,合理的磁场强度应控制在0.2～0.3 T.     

板坯结晶器电磁制动的模拟研究

采用低熔点金属模拟板坯电磁制动条件下结晶器内流场,使用超声多普勒测速仪测量结晶器内金属液流速.实验结果表明:电磁制动不仅能够抑制结晶器内金属液流动,而且能够改变流动方向和调节流速分布;单条型电磁制动能够增强上环流的流动,增大冲刷强度;流动控制结晶器能够改善上环流的流动,降低结晶器上部的冲刷强度.     

Φ150 mm圆坯结晶器电磁搅拌数值模拟研究

以结晶器电磁搅拌器为研究对象,建立了Φ150 mm断面结晶器电磁搅拌过程的电磁场与流场耦合的三维数学模型,并采用有限元软件进行求解。分别模拟不同条件下的结晶器电磁搅拌电流和不同电磁搅拌频率作用下钢液在结晶器内流动状态的规律。研究结果表明:随搅拌电流的增大,钢液的切向流速增加,上部环流区缩短,下部旋转流动区域上移并扩大,搅拌电流和频率对钢液流动的影响相反;在电磁搅拌过程中,电磁搅拌使结晶器内钢液产生旋转流动阻止过热钢液下移,减弱冲击深度,使热区明显的上移。     

Numerical Analysis of the Influences of Operational Parameters on the Braking Effect of EMBr in a CSP Funnel-Type Mold

A three-dimensional mathematical model of the magnetic field, flow field, and temperature field in a 1500 mm × 90 mm CSP funnel-type mold is used to numerically study the effect of an electromagnetic brake (EMBr) on flow and heat transfer behavior of molten steel. A number of effects of EMBr on the flow pattern and temperature distribution of molten steel are simulated. The jet flow discharge from the submerged entry nozzle (SEN) is significantly suppressed. In addition, heat transfer in the upper part of the mold increases under the influence of EMBr, which can improve the mobility of liquid steel at the meniscus and achieve low superheat casting. The relations between casting speed and magnetic flux density, and between SEN submergence depth and the installation position of the EMBr device, are taken into account to study the effects of braking on molten steel. The results show that the braking effect is weakened with an increase in either the casting speed or the SEN submergence depth. In order to insure the efficient and stable operation of a continuous casting production, the magnetic flux density should be increased by approximately 0.1 T when the casting speed increases by 1 m/min. In addition, an optimal braking effect for molten steel can be obtained when the distance between the bottom of the nozzle and the upper surface of the EMBr device is 100 mm.     

Study on fluid flow in the mold with electromagnetic braking

Multiphase flow control w ith electromagnetic braking( EMBr) is w idely used in the continuous casting of steel slabs. The basic aim of the flow control system of the process is to deliver molten steel from the ladle through the tundish,upper tundish nozzle,slide gate,and submerged entry nozzle into the mold region w ith minimal defects. This requires the optimization of turbulence levels at a meniscus to avoid both an excessively fast flow( which creates high fluctuations of the meniscus level in addition to slag entrapment,surface nonuniformities,and surface defects) and insufficient slow flow( w hich leads to meniscus solidification,inadequate flux infiltration,and surface defects). In this study,a Eulerian-Lagrangian approach is used to investigate the effects of EM Br and Ar bubble injection on the surface flow velocity. The results show that high Ar injection rates can lead to an increase in surface velocity.     

Large Eddy Simulations of the Effects of EMBr and SEN Submergence Depth on Turbulent Flow in the Mold Region of a Steel Caster

Transient turbulent flow in the mold region during continuous casting of steel is related to many quality problems, such as surface defects and slag entrainment. This work applies an efficient multi-GPU based code, CUFlow, to perform large eddy simulations (LES) of the turbulent flow in a domain that includes the slide gate, SEN, and mold region. The computations were first validated by comparing the predicted surface velocity with plant measurements. Then, seven LES simulations were conducted to study the effects of casting speed, electromagnetic braking (EMBr) field strength, and submerged entry nozzle (SEN) depth on the transient flow. The results show that EMBr has an important influence on flow inside the SEN, in addition to flow in the mold. With EMBr, an “M-shaped” flow profile is seen inside the SEN. The swirling flow behavior in the SEN and ports is more symmetrical at high casting speed and with higher EMBr strength. The position of the SEN ports relative to the peak magnetic field affects the EMBr performance. The results confirm and quantify how applying EMBr greatly lowers both the magnitude and turbulent variations of the surface velocity and level profile.     

Effect of Slide Gate and EMBr on the Transport of Inclusions and Bubbles in Slab Continuous Casting Strands

This study is to investigate the effect of electromagnetic brake (EMBr) on fluid flow and particle motion in steel slab continuous casting strands. The effect of slide gate moving on fluid flow pattern was discussed. A strong swirl and asymmetrical flow at the outports and, subsequently, inside the slab mold, was induced by slide gate. The application of EMBr would be a remedy to the swirl flow in the casting mold. Flow pattern has great influence on the trajectories of injected bubbles and nonmetallic inclusions. More bubbles tend to release from the top surface near the wide face opposite to the gate opening side without EMBr; while, they escape at the center place of the slab thickness when the EMBr was applied. Local brake type EMBr has a little effect on the overall removal fraction of nonmetallic inclusions, especially for the small ones. However, EMBr affects the distribution of inclusions on the cross section of the slab, and more inclusions were observed in the sub‐surface layer of the slab.     

Fluid Flow-Related Transport Phenomena in Steel Slab Continuous Casting Strands under Electromagnetic Brake

In the current study, a three-dimensinal (3D) numerical model is built to investigate the effect of a local-type electromagnetic brake (EMBr) on the fluid flow, heat transfer, and inclusion motion in slab continuous casting strands. The results indicate that the magnetic force affects the jet characteristics, including jet angle, turbulent kinetic energy, and its dissipation rate. To reduce the top surface velocity and stabilize the top surface, the magnetic flux intensity should be larger than a critical value. With a 0.39 T magnetic flux intensity, the top surface velocity and its fluctuation can be well controlled, and less slag is entrained. The motion of argon bubbles is also studied. More bubbles, especially >2.0-mm bubbles, escape from the top surface between the mold submerged entry nozzle (SEN) and \frac14 \frac{1}{4} width for the case with a 0.39 T EMBr. This may push the top slag away and create an open “eye” on the top slag. Small bubbles (≤1 mm) tend to escape from one side of wide face no matter with or without EMBr, which is induced by the swirl flow from the SEN outport. EMBr has a little effect on the overall removal fraction of inclusions; however, it affects the local distribution of inclusion in the slab. With EMBr, more inclusions accumulate the region just below the surface, thus a worse subsurface quality, whereas the inner quality of the slab is better than that without EMBr. For heat transfer in the mold, the heat flux on the narrow face and the area of possible break-out zones can be reduced by using EMBr. Prevention of bias flow and/or asymmetrical flow in mold by EMBr is also concluded.     

Optimum Position of Electromagnetic Brake on Slab Caster

SymbolList　　B———Magneticfluxdensity ,T ;　　CD———Dragcoefficient;　　d———Diameter ,m ;　　g———Gravitationalacceleration ,m·s-2 ;　　h———Timestep ,s ;　　J———Currentdensity ,A·m-2 ;　　la,lb———Sizeofslabcross section ,m ;　　ln———Immersiondepthofnozzle ,m ;　　p———Pressure ,Pa ;　　t———Time ,s ;　　u→ ———Velocity ,m·s-1;　　vc———Castingspeed ,m·min-1;　　X→ ———Displacement ,m ;　　———Electricpotential,V ;　　ρ———Density ,kg·m-3;…     

立式组合电磁制动对CSP结晶器内钢液流动及偏流控制

紧凑型带钢(CSP)薄板坯连铸结晶器在浸入式水口下方设置水平式的全幅一段电磁制动器(Ruler-EMBr),在进一步提高薄板坯连铸拉坯速度的情况下,不能有效控制CSP结晶器自由表面的钢液流速和液面的稳定性.为此提出一种新型的立式组合电磁制动(VC-EMBr)技术,并利用商业软件ANSYS FLUENT数值模拟研究了全幅...     

The Effects of Electromagnetic Brake on Liquid Steel Flow in Thin Slab Caster

Computational fluid dynamics (CFD) model with magneto hydro dynamics (MHD) is developed for a thin slab caster to investigate the effects of electromagnetic brake (EMBr) on liquid steel flow in continuous casting mold and to determine the EMBr practices which lead to optimal flow structure. Particle Image Velocimetry (PIV) tests in water model and meniscus flow measurements in real caster are performed to validate the predictions obtained with CFD models. The performance of different submerged entry nozzle designs, SEN 1 and SEN 2, are evaluated. The effects of nozzle submergence in relation to the applied magnetic field on mold flow structure are quantified. There are significant differences between flow structures obtained with SEN 1 and SEN 2, even though both designs have fundamental similarities and contain four ports. EMBr mainly reduces the meniscus velocities for SEN 2 as opposed to the foremost influence of EMBr for SEN 1 that is to significantly slow down the downward jet coming from the bottom ports. In addition, reducing the EMBr strength for shallow nozzle submergence and increasing the EMBr strength for deep nozzle submergence help to maintain similar meniscus activity for all conditions.     

Effect of Electromagnetic Ruler Braking (EMBr) on Transient Turbulent Flow in Continuous Slab Casting using Large Eddy Simulations

Static electromagnetic braking (EMBr) fields affect greatly the turbulent flow pattern in steel continuous casting, which leads to potential benefits such as decreasing flow instability, surface defects, and inclusion entrapment if applied correctly. To gain a fundamental understanding of how EMBr affects transient turbulent flow, the current work applies large eddy simulations (LES) to investigate the effect of three EMBr ruler brake configurations on transient turbulent flow through the bifurcated nozzle and mold of a liquid-metal GaInSn model of a typical steel slab-casting process, but with deep nozzle submergence and insulated walls with no solidifying shell. The LES calculations are performed using an in-house graphic-processing-unit-based computational-fluid-dynamics code (LES-CU-FLOW) on a mesh of ~7?million brick cells. The LES model is validated first via ultrasonic velocimetry measurements in this system. It is then applied to quantify the mean and instantaneous flow structures, Reynolds stresses, turbulent kinetic energy and its budgets, and proper orthogonal modes of four cases. Positioning the strongest part of the ruler magnetic field over the nozzle bottom suppresses turbulence in this region, thus reducing nozzle well swirl and its alternation. This process leads to strong and focused jets entering the mold cavity making large-scale and low-frequency (<0.02?Hz) flow variations in the mold with detrimental surface velocity variations. Lowering the ruler below nozzle deflects the jets upward, leading to faster surface velocities than the other cases. The double-ruler and no-EMBr cases have the most stable flow. The magnetic field generates large-scale vortical structures tending toward two-dimensional (2-D) turbulence. To avoid detrimental large-scale, low-frequency flow variations, it is recommended to avoid strong magnetic fields across the nozzle well and port regions.