八流一体式中间包的钢液流动特性分析

以单流中间包停留时间分布曲线(RTD曲线)组合模型为基础,充分考虑中间包各流流量对流动特性的影响,提出一个适合多流中间包的RTD曲线分析模型。该模型使中间包各流所对应的短路流、活塞流、混合区及死区的体积分数之和为100%,有效避免了传统组合模型所导致的各流股对应区域的体积分数之和偏大(超过100%)的情况,使之符合客观物理现实。模型选用短路流、活塞流、混合区及死区体积分数的标准差,进行各流流动一致性判断。以此为理论依据,采用水模拟实验,结合正交设计实验方法,确定八流一体式中间包控流装置的最佳组合为:低孔挡墙+低挡坝+盆式湍流抑制器。     

多流中间包钢液流动特性分析方法

中间包水模型实验一般采用脉冲刺激-响应实验,分析所得平均停留时间分布(RTD)曲线特征;然而经典组合模型处理多流中间包RTD曲线时经常出现负体积死区分率或结果偏差较大的问题.本文基于组合模型,采用阶段刺激-响应实验,分析所得累计停留时间分布F曲线特征,对死区比例和活塞区比例进行计算.该模型计算方法适用于多流中间包的流场特征计算.基于累计停留时间分布曲线特征分析,对某钢厂七流中间包控流装置结构进行优化,优化后的中间包死区比例降低,各流差异减小,有利于生产顺行和铸坯质量的提高.     

连铸中间包内钢液流动特性分析模型的研究进展

介绍了中间包内钢液流动特性分析模型的研究进展,针对中间包内钢液的去夹杂流动特性,论述了典型的单、多流中间包去夹杂流动特性分析模型,并通过对比分析找出了较优的单、多流中间包去夹杂流动特性分析模型。对于多流中间包内钢液的流动特性,不仅要考虑非金属夹杂物的去除,还要考虑多流中间包内各流流动特性的一致性,对比分析了典型各流流动特性一致性分析模型的特点并找出了合适的分析模型。所找到的合理的去夹杂及各流流动特性一致性分析模型为中间包内钢液流动特性分析提供了理论依据。     

多流中间包流动特征分析的全流量模型

针对多流中间包死区体积难于计算的问题，提出了一个全流量模型，并用模型计算了广州钢厂三流中间包的死区体积。实验中用热态水模模拟高温钢水流动过程时，由于介质水的电导率随温度变化，从模型直接测得的ＲＴＤ曲线应根据试验过程的温度进行修正。     

中间包导流挡板设计与冶金效果

为了提高6流方坯中间包冶金效果,通过中间包水力学模拟试验,研究了导流挡板中导流孔参数对中间包流场特征的影响,并对其进行极差分析,最终确定了导流挡板各参数影响中间包流场特征的主次顺序为:导流孔孔径＞倾角＞高度.并以此为指导思想,结合CFD数值仿真对导流挡板进行设计.设计方案为:3个导流孔直径分别为93、72、36 mm,位置分别为(220mm,140m m)、(350mm,280m m)、(700 mm,300mm),倾斜角度分别为(21°,15°)、(8°,23°)、(10°,28°).工业试验表明,设置该导流挡板装置可以有效改善钢液流动特性,提高中间包冶金效果.     

非对称型多流中间包的解析

对各种多流中间包的非对称性提出了一个定量描述的物理量－不对称渡Ｙ，并将各咎多流中间包分为完全对称型、一般非对称型，特殊非对称型等三类。对Ｙ的几个参数选取进行了讨论，得出了这几个参数与不对称度之间的关系，并指出在连铸中操作和设计方面应考虑的一些问题。     

非对称型多流中间包的解析

本文对各种多流中问包的非对称性提出了一个定量描述的物理量——不对称度Y,并将各种多流中间包分为完全对称型、一般非对称型、特殊非对称型等三类.对Y的几个参数选取进行了讨论,得出了几个参数与不对称度之间的关系,并指出在连铸中操作和设计方面应考虑的一些问题.     

多流中间包内钢液流动规律模拟研究

针对攀钢六流大方坯连铸中间包,采用等温和非等温物理模拟的研究方法,研究了钢水在中间包内的流动规律。实验结果表明自然对流对钢液的流动模式具有重要的影响,因此,对于体积大、流间距长的中间包必须采用非等温的模拟研究方法。实验还证明了在非等温情况下中间包内加控流装置的必要性。     

多流中间包流动特征的数学模型

提出了针对多流中间包流动特征的数学模型,给出了绘制停留时间分布(RTD)曲线的标准及其相关计算的规范;明确了\     

Water Modeling of Swirling Flow Tundish for Steel Continuous Casting

A conventional turbulence inhibitor is compared with a swirling chamber from the points of view of fluid flow and removal rate of inclusion in the tundish. Comparing the RTD curves, inclusion removals, and the stream-lines in water model experiments, it can be found that the tundish equipped with a swirling chamber has a great effect on improving the flow field, and the floatation rate of inclusion is higher than the tundish with a turbulence inhibitor. Because of the introduction of the swirling chamber, the flow field and inclusion removal in a two-strand swirling flow tundish are asymmetrical. Rotating the inlet direction of swirling chamber 60 degree is a good strategy to improve the asymmetrical flow field.     

Fluid Flow and Inclusion Motion in a Multi-Heat Teeming Tundish for Heavy Steel Ingot

 Besides the function of molten steel supply in the casting process, tundish has a capability of decreasing the formation of macro-scale inclusions and promoting the flotation of the remaining inclusions. Both the round shape tundish and the elliptical shape tundish were studied for the multi-heat teeming ingot. The transportation of molten steel and the motion of inclusions were compared using numerical simulation and physical modeling. The results showed that the short molten steel residence time, the large dead volume, and the low efficiency in inclusion removal for the round shape tundish were obtained even when a flow control device was installed. After comparing the two kinds of tundishes with the same capacity, it indicated that in the elliptical shape tundish, the molten steel residence time was prolonged by 1.6 times and the mean residence time increased by 6%; the dead volume was decreased from 18% to 13%, the ratio of the plug volume to the dead volume increased by 68%, and the inclusion flotation efficiency increased by 17%. The trial results indicated that, after using the elliptical tundish, the equivalent diameter of single defect was decreased from 2.5 to 1.6 mm, and no intensity defect was observed. The total oxygen content was 21×10-6, which was decreased by 30%.     

连铸中间包内夹杂物上浮规律的研究

 引入湍流涡旋的Kolmogoroff尺度作为区分钢液中夹杂物粒径大小的标准。对中间包内不同粒径夹杂物的上浮规律进行了理论分析,为中间包内夹杂物去除的实验研究提供了理论依据。采用不同的模拟介质对中间包内夹杂物的去除做了研究,验证了理论分析的正确性。     

Water Modeling of a Swirling Flow Tundish for Steel Continuous Casting

 A conventional turbulence inhibitor is compared with a swirling chamber from the points of view of fluid flow and removal rate of inclusion in the tundish. Comparing the RTD curves, inclusion removals, and the streamlines in water model experiments, it can be found that the tundish equipped with a swirling chamber has a great effect on improving the flow field, and the floatation rate of inclusion is higher than the tundish with a turbulence inhibitor. Because of the introduction of the swirling chamber, the flow field and inclusion removal in a two-strand swirling flow tundish is asymmetrical. Rotating the inlet direction of swirling chamber 60 degree is a good strategy to improve the asymmetrical flow field.     

Upward Molten Flow for Optimization of Fluid Flow in Continuous Casting Tundish

Fluid flow pattern and buoyancy force support the motion of nonmetallic inclusions toward the tundish slag. Upward molten flow was investigated. To understand the fundamentals of the process, physical modelling was carried out with the utilization of a 1∶4 scale model. Numerical modelling was carried out in line with the physical modelling to examine details of the flow pattern and rotational effect caused by the upward flow with the commercial CFD (Computational Fluid Dynamics) package environment, FLUENT. The two-equation k-ε model was used to simulate the turbulence. Multiphase fluid flow was numerically simulated by using the Volume of Fluid (VoF) method. The simulation can predict free surface waves and other phenomena, which can be used to optimize these important metallurgical operations.     

中间包内流体流动及夹杂物去除的研究

采用湍流流动的数学模型方法,对板坯中间包内的钢液流动及夹杂物去除率进行了模拟研究。系统分析了在中间包内设置控流设备对钢液流动状态、平均停留时间以及夹杂物颗粒排除率的影响。结果表明,设置挡墙和坝后,中间包内有效防止了短路流,延长了平均停留时间,夹杂物整体排除率明显提高,大大改善了中间包的冶金效果。     

Molten Steel Flow in a Slab Continuous-casting Tundish

Fields of fluid flow and temperature, and residence time distribution (RTD) curves were investigated by mathematical simulation in a one-strand tundish for continuous casting. It was known from the investigation that a big “spring uprush” formed on surface around the long shroud when molten steel flowed into a turbulence inhibitor (TI) with extending lips and rushed up reversely out of the TI, while four small “spring uprushes” existed on surface when a TI without extending lips because the liquid steel flowed mainly out of the 4 corners of the TI. The flow of liquid steel in the former tundish configuration was not reasonable and the height of an area where temperature was less than 1819 K was about half of liquid surface height on the right side of the stopper, which meant that big dead zone existed in the former tundish configuration. In the optimal one, the height of such area was only seventh of the liquid surface height. The RTD curves obtained from the mathematical simulation basically agreed with those from the physical modeling and the flow characteristics obtained from these two methods agreed with each other.     

六流连铸中间包内钢液流动的数值模拟

计算机模拟仿真作为一种参数优化的有效工具,在过程冶金中的应用已越来越广泛。对六流连铸中间包内钢水流动进行了计算机模拟研究后发现,原中间包设计存在不足,提出了优化的设想。     

钢水密度对板坯中间包流场影响的数学模型

利用数学模型研究了钢水在常密度和密度变化两种条件下板坯中间包内的流场、温度场和钢水平均停留时间。计算结果表明，高温钢水在中间包内流动时，不能忽略自然对流流动；密度随温度变化时，钢水沿着液面流到水口区，没有短路流现象，最短滞流时间１００ｓ，进出口温差４４℃，其流场和温度场与常密度条件下的正好相反。