钢的连铸过程结晶器与铸坯之间的传热分析

针对连铸过程中的结晶器传热模型，分析总结了结晶器与坯壳之间的热阻构成，并研究了结晶器壁和坯壳界面热流的影响因素，为传热模型的求解和结晶器锥度的优化设计提供了理论依据。     

连铸圆坯结晶器的热流分析

笔者采用专门设计的热流传感器对弧形连铸圆坯结晶器的热流进行在线检测.结果表明:沿结晶器的高度和周向热流的分布是瞬间变化且不均匀的.温度的在线检测不能代替热流的在线检测,后者可更准确和直接地反映结晶器传热和坯壳厚度的均匀性;同时在线检测结晶器的温度和热流有可能对结晶器的设备状态(如结晶器的安装状况和水垢状况)实现在线预测.     

圆坯连铸结晶器热流研究

 对圆坯连铸结晶器平均热流和局部热流进行了研究。分析了拉速、电磁搅拌电流和弯月面波动等工艺参数对结晶器局部热流(高热流区热流)和平均热流的影响。结果表明：拉速为14~26 m/min,搅拌电流在200~320 A时,局部热流与平均热流变化趋势不完全一致。局部热流对工艺参数反应敏感,传热极不均匀;平均热流不能完全反映局部热流的变化,局部热流能更及时地反映坯壳的凝固情况。     

基于Fluent对水平连铸结晶器温度场分布及传热的研究

以水平连铸圆坯连铸生产工艺为研究对象,采用Fluent数值模拟软件凝固传热模型并结合射钉试验共同研究了管坯在不同拉坯工艺条件下,结晶器内的温度场分布与凝固传热过程,并对不同拉坯参数下铸坯试样进行了检测分析。研究发现：水平连铸拉坯工艺参数：拉速V=2．13m／min,浇注温度T=1544℃,中间包过热度△T=40℃的拉坯参数下,结晶器内的温度场分布均匀稳定,铸坯质量好,产量高。研究表明,采用Fluent数值模拟软件凝固传热模型并结合射钉试验可以有效分析在不同拉坯工艺条件下水平连铸结晶器内的温度场分布及凝固传热过程,并进一步制定合理的拉坯工艺参数,降低管坯质量缺陷的发生,提高铸坯质量。     

The Effect of the Transition Metal Oxide Content of a Mold Flux on the Radiation Heat Transfer Rates

Heat transfer in the mold of a steel continuous casting machine strongly influences cast surface quality. Transition metal oxides have been widely used in mold slags in continuous casting to aid in liquid pool formation and enhance melting rates. Although a few research studies have been carried out to investigate the thermal properties of mold slags containing transition metal oxides, very few studies have directly correlated their effect on radiation heat transfer rate in continuous casting. This study investigates the radiation heat transfer rates across a mold flux film and determines the influence of the transition metal oxides, MnO and Fe₂O₃, on these rates. It is found that additions of 10% MnO or 5% Fe₂O₃ reduce the radiation heat transfer rate by approximately 25% and increase the adsorption coefficient from 400 to 1800 m^?1.     

连铸结晶器保护渣结晶性能的研究

实验研究了结晶器保护渣(％:37CaO、2MgO、40SiO₂、5Al₂O₃、5Na₂O、11CaF₂)在1 300-1 000℃的结晶过程和性能。结果表明,冷却速率≤2℃／s时,该渣的结晶化率达100％。在冷却速率0．1℃／s时,保护渣首先析出树枝状晶体,然后以片状晶体形态析出,直到结晶终止。通过X-射线衍射分析,得出析出的晶体主要有枪晶石(Ca₄Si₂O₇F₂)镁黄长石(Ca₂MgSi₂O₇)、硅灰石(CaSiO₃)及镁铝尖晶石(Al₂MgO₄)。     

连铸机辊子与铸坯传热的研究

根据连铸机辊子的实际工作情况，将其内外表面分成传导传热区，对流换热区和辐射－对流综合换热区。利用距辊子表面３ｍｍ处所测得的温度变化曲线，通过辊子换热的平衡方程，推导出每一区域的综合传热系数及其表面温度的表达式，为正确计算辊子的温度场，供应力提供了较为可靠的依据。     

连铸保护渣性能研究及改进

对连铸保护渣的粘度—温度曲线及熔化温度性能等进行了试验研究，得出基本组分对保护渣性能的影响规律；对粘度—温度曲线形状的分析研究，确定了保护渣的性能改进方向，结合济钢连铸生产中存在的问题，开发出两种新的保护渣。     

Investigation of Heat Transfer in the Spray Cooling of Continuous Casting

The heat transfer coefficient between spray water droplets and hot surface is measured in the laboratory. The effect of spray water flow rate, water pressure, spray distance of nozzle from the surface of strand, spray water temperature on the heat transfer is made a detail studied. And meanwhile, the effect of the strand surface FeO scale on the heat transfer is also investigated. According to the experimental results, the influence of above factors on the heat transfer coefficient has been discussed and a experience formula between the heat transfer coefficient and spray water flow rate is given out.     

软接触电磁连铸过程中结晶器及初生坯壳的传热

为了解高频磁场对软接触电磁连铸结晶器及初生坯壳传热行为的影响,用有限元二维数值模拟方法计算了软接触连铸过程中结晶器及初生坯壳的传热.得知在高频磁场（f=20 kHz）作用下,电磁场的感应加热会减少连铸初生坯壳的厚度、提高连铸坯的表面温度,并大幅度提高分瓣结晶器铜壁的温度.     

板坯连铸中间包流场及传热特征模拟研究

对某钢厂现有板坯连铸中间包进行流场模拟研究,研究结果表明,原结构的中间包内钢水停留时间短,死区体积大。通过优化设计使流场得以改善,并用数学模拟的方法进行了流场及传热特征计算,验证了水模试验得到的优化方案的合理性。     

Heat Withdrawal in the Mold in Continuous Casting of Steel. Review and Analysis

Two principal methods are used to investigate the heat transfer in the continuous casting mold. The direct way is to measure cooling water temperatures, mold wall temperatures, strand temperatures and shell thickness in actual operation, and then deduce from these data the correlations for heat flux densities. The other way is to investigate the “unit operations” of heat transfer theoretically or experimentally in the laboratory, viz. heat transfer through a layer of casting flux or of gas, and heat transfer in a copper wall cooled on one side by water. The results obtained in this approach can then be used to explain the data determined with the direct method and to optimize the heat transfer behaviour of the mold in the machine. In the first part of this paper some unit operations are discussed and engineering formulae are given for computation of the heat resistances of the gap and the copper/water system. In the second part of the paper the available operational data on heat flux density are analysed. Algorithms are presented for computation of local and average heat flux density as functions of casting speed, carbon content of the steel and composition of the casting flux. Finally, values of shell thickness are computed with the correlation for heat flux density and are compared with the measured data.     

热送热装工艺中板坯连铸过程传热的数学模型

建立了板坯连铸过程传热数学模型，并用实测数据对计算结果进行了验证，证明该模型可用于预报不同操作条件下板坯凝固过程中温度的变化和凝固状态。应用该模型分析了影响板坯出连铸机温度的主要因素：板坯尺寸、拉速、二冷水量及冷却方式等。适当提高拉速、改善二冷制度能提高铸坯出连铸机温度。     

Heat Transfer and Deformation Behavior of Shell Solidification in Wide and Thick Slab Continuous Casting Mold

With the considerations of the behaviors of shell deformation, mold flux film and air gap dynamic distribution in shell/mold gap, a two dimensional slice-travel transient thermo-mechanical coupled model of simulation shell solidification in wide and thick slab continuous casting mold was developed by using the commercial program ANSYS. The evolutions of strand-mold system thermal behaviors, including the air gap formation and the mold flux film dynamical distribution in shell/mold gap and shell temperature field, and the evolutions of shell deformation and stress distribution of peritectic steel solidified in a 2120 mm wide and 266 mm thick slab continuous casting mold were analyzed. The results show that the air gap formation and the thick mold flux film distribution mainly concentrate in the regions 0–21 mm and 0–7 mm, 0–120 mm and 0–100 mm off the shell wide and narrow faces corners, and thus the hot spots are given rise to form in the regions 15–55 mm and 15–50 mm off the shell wide and narrow face corners. The shell server deformation occurs in the off-corners in the middle and lower parts of the mold. The stress evolution in shell surface is tensile stress, while that in shell solidification front is compressive stress.     

A 3D Mathematical Modeling on Meniscus Solidification and Heat Transfer in Continuous Casting Chamfered Mold of Slab

Herein, a 3D mathematical model is established to elucidate the meniscus solidification and heat transfer in the chamfered mold. The fluid flow, heat transfer, the solidification of steel, the oscillation of the mold, and the steel–slag interfacial tension are considered, and the meniscus behavior on different longitudinal sections and cross sections is discussed. Under the influence of the upper roll flow, the height of the steel level increases from submerged entry nozzle to narrow face, which affects the distribution of the oscillation mark on the surface of the shell. With the mold chamfer and two new corners, the thickness of the slag film at the corner 1 with angle of 123.7° is the largest, and the shell thickness is the smallest, which is related to the 3D profile of the meniscus near the corner. The largest heat flux is located at 10–14 mm below the initial level of liquid steel and is below 3.0 MW m⁻². The heat flux at the corner 1 with small obtuse angle is the smallest on the same cross section, indicating that small obtuse angle near the corner resulted in the low heat transfer.     

连铸用气-水雾化喷嘴的传热特性

报导了一种气—水雾化喷嘴的测定结果,并与一种水喷嘴进行了比较。研究表明,采用气—水雾化喷嘴时,铸坯二冷的传热系数不仅和水流密度有关,而且与喷射状况,诸如水滴直径,水流密度、气-水雾化喷嘴的用气量等条件有关。     

拉速对结晶器平均热流的影响

通过计算8088块板坯的平均热汉研究了拉速对板坯结晶器平均热流的影响结果表明：拉速对结晶器宽边的平均热流有显的影响,拉速在0．6－1．2m/min范围内,结晶器宽边平均热流随拉速提高而增加,当拉速超过1．2m/min后,结晶器宽边平均热流随拉速增加而提高的幅度变得很小;结晶器窄边的平均热流较宽边的热流约低0．2MW／m^2,当拉速超过1．2m/min后,结晶器窄边的平均热流仍可随拉速的进一步提高而增加。     

厚板坯连铸二冷凝固传热模型的研究与应用

以鞍钢厚板坯连铸机为目标机型,按照传热学理论建立连铸二冷凝固传热数学模型.应用此模型对X65管线钢和船板钢的连铸过程进行仿真模拟,模拟结果同实测值基本吻合,验证了模型的可靠性.     

连铸二冷传热系数测定仪的研制

本文说明了测定传热系数对连铸的重要性,给出了计算传热系数的方法。所研制的传热系数测定仪包括加热控温系统、温度信号放大与采集系统、数字计算与打印系统等。测定仪装有8位单板计算机和24行微型点阵式打印机。从加热温度传感器到打印测定结果,整个测试过程可连续自动进行。在同样条件下的测定结果稳定可靠。     

单辊薄带连铸凝固传热数学模型

本文以单辊薄带连铸机为研究对象,通过建立传热数学模型,结合热态试验,找出带厚与工艺因素之间的关系,从而为生产出较好质量带坯提供工艺参数。