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真空精炼过程循环流量的水模型研究

建立了钢厂250 t RH真空精炼装置1/4的水模型,研究浸渍管内径(520～750 mm)、驱动气体流量(1 000～3 000 L/min)、浸渍管浸入深度(525～800 mm)和真空室压力(0～25 kPa)等参数对RH循环流量的影响。结果表明,随驱动气体流量、浸渍管浸入深度增加、浸渍管内径增大以及真空室压力减少,RH钢水循环流量增加;为获得较大流量,浸渍管浸入深度应≥560 mm,真空室液面高度应≥200 mm。得出循环流量的回归方程,通过对钢厂250 t RH设备工艺参数作相应调整后,RH装置的生产效率明显提高。     

弓形浸渍管RH钢液流动行为的物理模拟

为了提高RH真空精炼系统的效率,设计了一种弓形浸渍管结构的RH真空槽。通过水模型试验对弓形和传统圆形浸渍管的RH设备进行了循环流量和均混时间的测定。试验发现:在实际生产条件下,弓形浸渍管RH比传统圆形浸渍管RH循环流量增加100%～180%;均混时间比传统RH减少35%左右。当提升气体流量超过饱和值时,弓形浸渍管RH的循环流量随着提升气体流量的增大而更加明显。弓形浸渍管RH可显著提高精炼效率,具有重要的应用前景。     

弓形浸渍管RH混合传质均匀性的数值模拟

为了提高RH系统真空精炼的效率,采用了一种新型弓形浸渍管RH装置.通过欧拉-欧拉方法对弓形浸渍管RH装置进行了数值模拟,计算了循环流量、均混时间、真空室液面流速分布、真空室内传质均匀性、真空室内RTD和钢包内RTD,并与传统RH进行对比.结果表明,在实际生产条件下,弓形管RH的循环流量比传统RH增加了91％～99％,均混时间比传统RH减少了25％～55％.弓形管RH真空室内传质比传统RH更均匀.弓形管RH真空室内活塞流体积分数为93.1％,比传统RH增加了13.7％;弓形管RH钢包内死区体积分数为21.03％,比传统RH减小了26％左右.综合考虑,弓形浸渍管RH可显著提高精炼效率及传质均匀性,具有重要的应用前景.     

RH精炼循环流量优化的水模型研究

以70 t钢包RH精炼装置为原型建立了1:3.27水模型,用流速法测量RH循环流量。分析了实际工艺条件下钢水的RH循环流量以及上升管吹气量、吹气孔内径、吹气孔高度、浸渍管插入深度等参数对RH循环流量的影响,并得出优化工艺参数。70 t钢包RH精炼实验结果表明,当上升管吹气量1 200 L/min,吹气孔内径3 mm时,轴承钢平均[O]比原工艺降低3×10^-6;超低碳钢碳含量可降低到0.002%以下,脱碳时间比优化前明显减少。     

不同侧吹参数下RH内气液两相循环流动模拟研究

通过建立包括真空室、浸渍管、钢包的180 t RH气液流动三维物理数学模型，采用VOF两相流模型和应用FLUENT软件进行数值模拟研究了侧吹氩气喷孔布置方式及吹气量对RH内气液两相循环流动的影响。分析了喷气孔单层布置和双层交错布置对喷气流量和上下层间距对上升管出口截面含气率、上升管和下降管出口速度以及循环流量的影响。结果表明，氩气在上升管内贴壁上升，并携带钢液向上运动，沿着运动方向管内截面含气率逐渐增加，在出口截面处含气率达到最大；上升管出口截面含气率越小，上升管出口和下降管出口截面中心速度越大，循环流量越大，均混时间越短；喷气管双层布置、减小间距、增大吹气量，有利于循环流量的提高和均混时间的缩短。     

循环流化床物料循环流率的测量

本文就作者自行研制的颗粒叶轮流量计用于测量循环流化床物料循环流率进行了研究。证明将叶轮颗粒流量计装入循环床的下料管密相段内，可准确地测量物料循环流率。与此同时，也与色点示综法和压差法等常规方法进行了比较，证明叶轮法是一种准确、可靠、简单、且可在线的测量方法。     

145 t RH真空精炼装置内钢液循环流动特性的水模型研究

基于相似原理,建立几何相似比1:7水模型研究了145t RH真空精炼装置内钢液循环流动行为,研究了提升气量(60~140 m³/h) 、浸渍管浸渍深度(400~600 mm) 、真空室液面高度(426~526 mm)对钢水循环流量和混匀时间的影响。结果表明,循环流量随提升气量增加而增大且呈近似线性关系,混匀时间随提升气量增加而呈非线性减小;500 mm的浸渍管浸渍深度和526 mm的真空室液面高度下均出现较理想的循环流量;130 m³/h提升气量、600 mm浸渍管浸渍深度和526 mm真空室液面高度可获得最佳循环流动特性。     

REDA与RH精炼过程钢液流动规律比较

以300 t REDA和RH精炼装置为研究对象,借助计算流体力学软件模拟REDA与RH两种精炼工艺下钢液流动行为,从精炼过程流场形态、循环流量、氩气行程及熔池表面湍动能等方面进行分析,研究结果表明:RH对钢包底部熔池的搅拌作用强于REDA,REDA的单浸渍管结构有利于延长浸渍管寿命及提高钢液循环流量,REDA只需RH提升气体流量的30%便能达到相同的循环流量。     

RH精炼过程钢液流动行为与循环流量数值模拟

以某厂300 t RH-MFB工艺参数为基础,建立了整体RH装置的三维数学模型,探讨影响钢液循环流量的因素.用双流体模型处理气液两相流,分析了相同真空度条件下吹氩流量、浸渍管深度、吹氩喷嘴排布等因素对钢液流场和循环流量的影响.结果表明:吹氩流量在4 000 NL/min以下时,循环流量随吹氩流量增加而提高;在一定范围内适当增加浸渍管插入深度有利于提升循环流量;吹氩喷嘴上下交错排布比上下一致排布更合理.     

Circulation rate of liquid steel in RH degassers

Vacuum-decarburization with the Ruhrstahl-Heraeus process is used for the production of ultra-low carbon steels. One important aspect of the RH process is the circulation of liquid steel between the degassing unit and the transport ladle. Thus, supervisory control of the RH treatment requires precise mathematical modelling of the circulation rate. In this work, a numerical model of the circulation flow is described in detail. This newly developed model as well as a frequently used semi-empirical equation are compared with measured data. It is shown that the numerical model is in far better accordance with the measured data than the semi-empirical equation. The numerical model is then applied to data of a conventional RH treatment. Special emphasis is put on the coupling of circulation rate and reaction rate. Both, circulation rate and reaction rate, are calculated as a function of time.     

RH真空精炼过程的动态模拟

建立了描述RH真空精炼装置内钢液动态脱碳（脱气）模型。对RH真空精炼时的脱碳、脱氧、脱氮和脱氢过程进行了动态模拟研究，考察了浸渍管直径、循环流量、吹氩量、氧含量和真空度对脱碳和脱气过程的影响。动态脱碳（脱气）模型考虑了反应机理，认为脱碳是通过上升管中Ar气泡表面、真空室中钢液的自由表面和真空室钢液内部脱碳反应生成的CO气泡表面进行的，并且考虑了精炼处理时的抽真空制度。该模型能全面描述RH精炼过程中不同时刻钢液中碳、氧、氮和氢的含量，能较好预测实际过程，可用于RH真空精炼过程的优化和新工艺开发。     

Cold Model-Based Investigations to Study the Effects of Operational and Nonoperational Parameters on the Ruhrstahl–Heraeus Degassing Process

The circulation rate of steel is known to play a vital role in the superlative performance of the Ruhrstahl–Heraeus (RH) degasser. Numerous experiments were conducted on a physical model for the RH degassing process, which was established at IEHK, RWTH-Aachen University. The model was developed with a scale ratio of 1:3 to study the RH process. This study is conducted to show the effects of operational and nonoperational parameters on the circulation rate of liquid water in the model. The effects of lift gas flow rate, submerged depth of snorkels, water level in vessel, etc. on the circulation rate are studied. The mixing characteristics are studied with the help of current conductivity experiments for different lift gas flow rates and water levels in the vacuum vessel. Finally, the relationship between dimensionless numbers is derived with the help of the experimental data obtained from the cold model.     

Mathematical modelling of decarburisation and degassing during vacuum circulation refining process of molten steel: application of the model and results

The mathematical model for decarburisation and degassing in the vacuum circulation refining process of molten steel, proposed and presented earlier, has been applied to the refining process of molten steel in a multifunction RH degasser of 90 t capacity. The decarburisation and degassing processes in the degasser under the RH and RH‐KTB operating conditions have been modelled and analysed using this model. It was demonstrated that for the RH and RH‐KTB refining processes, the results predicted by the model are in good agreement with some plant data. The mean contributions of the three refining sites in six circulation cycles to decarburisation are 10.5 – 11.6, 37.4 – 38.0 and 50.5 – 52.1 % of the overall amount of decarburisation, respectively. The KTB operation can markedly accelerate the decarburisation of molten steel. Using the top blowing oxygen of 6 min with the flow rate of (600 ‐ 1000) m³(STP)/h, the initial carbon mass content of the liquid steel for the RH refining process may be increased to (550 ‐ 700) · 10‐⁴ from 400 · 10‐⁴ %. And the treatment time needed for reducing the carbon mass content in the steel to a level of ≤ 20 · 10‐⁴ % may be shortened over 3 ‐ 4 min. The effectiveness of decarburisation and degassing cannot be obviously improved by increasing the lifting argon blow rate to 900 from 600 I(STP)/min under the operating modes examined in the present work.     

天津钢管公司100t RH的设备功能和冶金效果

国内自行设计制造的100 t RH真空循环脱气设备的真空度可达67 Pa以下,真空处理能力为500kg/h以上。生产实践表明,氩气流量越大,钢水循环速度越大,高真空脱气时间越长,钢水脱气效果越明显,所处理的管线钢的氢、氧、碳含量可分别降至1×10^-6、20×10^-6和20×10^-6以下。     

1号RH真空槽冶金反应器类型水模型研究

通过水模型实验研究对ＲＨ真空槽反应器类型给予了重新论证,真空槽内钢水平均停留时间小于７ｓ,随循环流量的增大而减小。ＲＨ真空槽反应器类型接近活塞流反应器。     

Mathematical modelling of decarburisation and degassing during vacuum circulation refining process of molten steel: mathematical model of the process

Based on the mass and momentum balances in the system, a new mathematical model for decarburisation and degassing in the vacuum circulation refining process of molten steel has been proposed and developed. The refining roles of the three reaction sites, i.e. the upsnorkel zone, the droplet group and steel bath in the vacuum vessel, have been considered in the model. It was assumed that the mass transfer of reactive components in the molten steel is the rate control step of the refining reactions. And the friction losses and drags of flows in the snorkels and vacuum vessel were all counted. For the refining process of molten steel in a 90 t multifunction RH degasser, the parameters of the model have been discussed and more reasonably determined.     

RH工艺生产轴承钢脱氧和去除夹杂物研究

针对RH工艺生产w(T.O)小于0.0010%的轴承钢,通过现场试验研究了RH纯脱气时间、吹氩量和初始T.O对脱氧和去除夹杂物的影响。试验结果表明:延长RH纯脱气时间可以显著降低钢中T.O和夹杂物的数量;RH提升气体量由60m3/h增大到72m3/h,取得良好的脱氧效果;RH真空处理14min的T.O受初始T.O的影响比真空处理25min的大。     

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.