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。     

RH高效深度脱碳与协同脱氧关键技术

围绕IF钢RH精炼高效深度脱碳与协同脱氧目标，从RH精炼碳氧热力学入手，分析了RH脱碳与协同脱氧的可行性和策略；从脱碳反应动力学入手，分析了不同脱碳阶段高效脱碳策略。同时，研究了RH强制脱碳、吹氧流量与枪位控制等高效脱碳与控氧协同技术，以及真空压降控制、循环流量优化、真空罐内部吹氩强化脱碳等RH精炼高效脱碳关键技术和RH精炼脱碳终点氧含量控制、顶渣氧化性控制等控氧关键技术，进一步提出通过上述技术集成应用实现RH高效深度脱碳与脱氧的协同策略。     

RH法的脱碳及脱硫速率

评述了RH法真空脱碳、脱硫反应过程的行为,着重叙述了真空环流二次精炼条件下反应速率方面的主要研究概况.     

梅钢RH炉镀锡基板碳控制技术

简要介绍了RH精炼脱碳原理、动力学条件。结合梅钢生产实际,阐述了镀锡基板RH真空脱碳条件及生产控制要点。     

120 t RH-LF生产低碳钢QD08的工艺实践

介绍了芜湖新兴铸管有限责任公司炼钢厂采用RH-LF精炼法生产低碳钢QD08的工艺实践。通过对转炉出站钢水初始条件,RH真空脱碳原理和过程控制,后续LF冶炼3个方面的分析研究,结果表明,初始钢水控制条件为[C] 0.04%～0.10%,[0]>300×10^-6,转炉终点出钢温度T≥1 650℃。随真空处理时间延长,真空度降低,真空室内PCO减少,碳氧浓度积呈降低的趋势,真空室内因发生碳氧反应进行脱碳,RH真空脱碳满足热力学条件;脱碳速率的变化规律为先增大后减小,脱碳速率有一定的规律;RH真空处理后的钢水需在LF完成脱硫、升温、合金化等操作,并且需保证终渣量20～23 kg/t,终渣（FeO）+（MnO）<1.2%,碱度R≥3.5等工艺条件。     

CO2作为RH提升气的冶金反应行为研究

钢液真空循环脱气法（RH）精炼能够利用高真空和钢液循环流动有效脱气和去除夹杂物。同时,炼钢环境下 CO₂可与钢液中[C]反应生成CO提高搅拌强度。因此,本文提出将CO₂作为RH提升气进行真空精炼。针对CO₂在RH精炼过程的冶金反应行为特性,通过热力学理论分析了极限真空条件下CO₂脱碳的有利条件及限度,同时搭建了CO₂作RH提升气工业试验平台,通过工业试验对比研究了CO₂/Ar分别作提升气时对钢液精炼过程的影响。结果表明,若单纯考虑CO₂与碳反应,则当钢液中[C]低于1.8×10?6,CO₂仍然具有氧化碳元素的能力。然而,CO₂对钢液中碳铝元素存在选择性氧化,当铝含量低于一定程度时,CO₂主要参与脱碳反应;反之,CO₂则会造成一定铝损,因此若采用新工艺需考虑铝合金加入时机以及加入量。此外,CO₂用作RH提升气可获得与Ar效果相当甚至更优的脱氢效果,喷吹同等量CO₂并未造成钢液的大幅温降,因此CO₂完全有潜力作为RH提升气,进而完成精炼。      

QD08生产RH真空精炼脱碳影响因素分析

结合芜湖新兴铸管炼钢部RH自然脱碳冶炼低碳钢QD08的生产实际,从热力学和动力学的角度出发,考虑初始碳氧含量以及真空度变化等因素,研究RH的碳氧反应,系统分析和研究低碳钢QD08钢生产的工艺制度。RH真空处理过程中,随真空处理时间延长,真空度降低,真空室内PCO降低,碳氧浓度积呈降低的趋势,真空室内因发生碳氧反应进行脱碳,RH自然脱碳满足热力学条件;RH自然脱碳反应速度取决于:[C]、[O]元素在钢液内部的传质系数、真空处理时间、抽真空的速度和脱碳速率,并具有一定的规律。对RH自然脱碳及其反应机理进行探讨,并且为利用RH装置生产低碳钢提供了重要技术支持。     

180t RH工艺技术优化与改进

针对180 t RH精炼工艺存在的真空度低、超低碳钢处理时间长、钢中氧含量高及脱硫效率低等问题,研究并优化了RH真空脱气、脱碳升温、脱氧、脱硫等工艺,使RH工作真空度提高到100 Pa以下,超低碳钢处理时间缩短至平均36.5 min,超低碳钢钢中氧的质量分数最低为13×10-6。优化工艺降低了钢中[H]、[N]、[C]、[O]、[S]等元素的含量,提高了钢水洁净度,缩短了RH精炼时间,提高了RH精炼生产率。     

RH强制脱碳与自然脱碳工艺生产IF钢精炼效果分析

西昌钢钒厂由于转炉热量不足而以转炉—LF精炼—RH精炼—连铸工艺生产IF钢,为探究RH强制脱碳与自然脱碳工艺生产IF钢精炼效果,采用生产数据统计、氧氮分析、夹杂物自动扫描、扫描电镜和能谱分析等手段,对不同脱碳工艺对顶渣氧化性以及钢的洁净度影响进行了详细研究。结果表明:（1）与自然脱碳工艺炉次相比,采用强制脱碳工艺的炉次在转炉结束与RH进站钢中的平均[O]含量更低;（2）两种工艺脱碳结束钢中的[O]含量基本在同一水平;（3）强制脱碳工艺的炉次在RH结束时渣中平均T.Fe的质量分数降低了1.3%。在能满足RH脱碳效果的前提下,尽量提高转炉终点钢液碳含量、降低钢液氧含量,后续在RH精炼时采用强制吹氧脱碳工艺,适当增大吹氧量来弥补钢中氧,可显著降低IF钢顶渣氧化性。自然脱碳工艺与强制脱碳工艺控制热轧板T.O含量均比较理想;与自然脱碳工艺相比,强制脱碳工艺可有效降低IF钢[N]含量,这与强制脱碳工艺真空室内碳氧反应更剧烈所导致的CO气泡更多和气液反应面积更大有关。脱碳工艺对IF钢热轧板中夹杂物类型、尺寸及数量没有明显影响,夹杂物主要由Al₂O₃夹杂、Al₂O₃–TiO_x夹杂与其他类夹杂物组成,以夹杂物的等效圆直径表示夹杂物尺寸,以上三类夹杂物平均尺寸分别为4.5、4.4和6.5 μm,且钢中尺寸在8 μm以下的夹杂物数量占比高于75%。在RH精炼过程中,尽量降低RH脱碳结束钢中[O]含量,有利于提高钢液洁净度。      

超低碳钢RH混合喷吹Ar-CO2冶金反应特性

 钢铁生产过程CO₂的资源化利用对中国“碳达峰,碳中和”目标的实现起着重要作用。氩气驱动的RH(ruhrstahl-heraeus)真空装置是超低碳钢精炼的关键设备,利用高真空下钢水循环流动可有效脱碳、脱气和去除夹杂物。由于真空条件下CO₂可直接与钢水中碳反应生成CO,在实现脱碳的同时可促进熔池搅拌。因此,尝试将Ar-CO₂混合气体作为提升气体引入超低碳钢RH脱碳过程。首先,针对CO₂在RH脱碳条件下的冶金反应行为,通过热力学理论分析了不同压力下Fe-C-O熔体与Ar-CO₂的反应特性。其次,搭建了Ar-CO₂混合气体作为RH提升气体的工业试验平台,通过工业性试验研究了超低碳钢RH脱碳过程混合喷吹Ar-CO₂对钢水脱碳、脱氮和温降的影响。Fe-C-O熔体与Ar-CO₂反应热力学表明,在低于100 kPa和超低碳条件下,Ar-CO₂混合气体中的CO₂仍可能与钢水中碳反应,从而促进RH脱碳和脱气。工业性试验表明,喷吹100% CO₂、50% Ar+50% CO₂和100% Ar炉次出站平均碳质量分数分别为0.001 50%、0.001 57%和0.001 19%,因而混合喷吹Ar-CO₂并不会显著影响RH脱碳效率。同时,由于CO₂与钢水中碳反应十分有限,与喷吹100% Ar相比,喷吹100% CO₂和50% Ar+50% CO₂对RH脱氮效率和钢水温降没有明显影响。因此,超低碳钢RH脱碳时,完全可采用CO₂取代部分或全部氩气作为提升气体,尽管无法提高精炼效率,但仍具有显著的经济价值和环保优势。     

120 t RH自然脱碳精炼低碳钢QD08的生产实践

基于生产数据对120 t RH精炼低碳钢QD08(/%:≤0.07C,0.15～0.35Si,0.25～0.45Mn,≤0.035P,≤0.035S)进行了RH碳氧反应的热力学、动力学分析和自然脱碳分析,得出RH精炼自然脱碳的优化工艺。结果表明,BOF终点温度≥1650℃,RH初始温度≥1 600℃,BOF终点[C]0.04%～0.10%,[P]≤0.018%,出钢前加顶浇石灰200 kg,出钢不加合金和脱氧剂,RH真空度4～8 kPa,6～8 min可使钢水[C]≤0.05%。     

RH喷吹参数对循环流量和均混时间影响的物理模拟

以某厂300tRH真空精炼装置为研究原型,建立1∶6.5的水力模型对RH喷吹精炼工艺进行物理模拟。研究了喷吹位置、喷吹气量及驱动气体流量对循环流量和均混时间的影响。结果表明:不同喷吹气量、驱动气体流量条件下,获得大循环流量和短均混时间的最优喷吹位置不同。较小的喷吹气量(2.98~3.53m3/h)或者较小的驱动气体流量(0.93~1.02m3/h)时,宜采用低顶枪枪位(153.8mm)喷吹;喷吹气量大于3.91m3/h或者驱动气体流量大于1.12m3/h时,宜采用真空槽底部喷吹角度120°的侧喷嘴喷吹。顶枪与侧喷嘴复合喷吹有利于提高RH喷吹工艺的适应性及循环效率。     

Mathematical Modelling of Non‐equilibrium Decarburization Process during Vacuum Circulation Refining of Molten Steel: Application of the Model and Results (I) ‐ Decarburization Process and Influences of Some Technological Factors

A novel three‐dimensional mathematical model proposed and developed for the non‐equilibrium decarburization process during the vacuum circulation (RH) refining of molten steel has been applied to the refining process of molten steel in a 90‐t multifunction RH degasser. The decarburization processes of molten steel in the degasser under the conditions of RH and RH‐KTB operations have been modelled and analysed, respectively, using the model. The results demonstrate that the changes in the carbon and oxygen contents of liquid steel with the treatment time during the RH and RH‐KTB refining processes can be precisely modelled and predicted by use of the model. The distribution patterns of the carbon and oxygen concentrations in the steel are governed by the flow characteristics of molten steel in the whole degasser. When the initial carbon concentration in the steel is higher than 400 · 10⁻⁴ mass%, the top oxygen blowing (KTB) operation can supply the oxygen lacking for the decarburization process, and accelerate the carbon removal, thus reaching a specified carbon level in a shorter time. Moreover, a lower oxygen content is attained at the decarburization endpoint. The average contributions at the up‐snorkel zone, the bath bulk and the free surface with the droplets in the vacuum vessel in the refining process are about 11, 46 and 42% of the overall amount of decarburization, respectively. The decarburization roles at the gas bubble‐molten steel interface in the up‐snorkel and the droplets in the vacuum vessel should not be ignored for the RH and RH‐KTB refining processes. For the refining process in the 90‐t RH degasser, a better efficiency of decarburization can be obtained using an argon blow rate of 417 I(STP)/min, and a further increase in the argon blowing rate cannot obviously improve the effectiveness in the RH refining process of molten steel under the conditions of the present work.     

Mathematical Modelling of Non‐equilibrium Decarburization Process during Vacuum Circulation Refining of Molten Steel: Application of the Model and Results (II) ‐ Non‐equilibrium Factors and their Influences on the Decarburization Process

The results, which were obtained by applying the novel three‐dimensional mathematical model proposed and developed earlier [1] to model and analyse the decarburization process of molten steel during the RH and RH‐KTB refining in a 90‐t multifunction RH degasser, showed that under the conditions of the present work, the contributions of the flow, mass diffusion and chemical reactions and other non‐equilibrium processes to the Raleigh‐Onsager dissipation function are not large throughout vacuum circulation refining of molten steel. Thus, it is held everywhere in the whole flow field of the system that the value of the non‐linear dissipation factor is approximately equal to one. The entropy generation and energy dissipation in the system rapidly decrease with increasing refining time. Compared to the work done by the drag force while the bubbles passing through the liquid phase as well as by the viscous and turbulent flow and diffusion processes, the carbon‐oxygen reaction itself plays a more governing role to the entropy production and energy dissipation in the system. The RH refining process of low and ultra‐low carbon steels seems to be close to the linear zone of the non‐equilibrium state. The influences of the viscous and turbulent flow dissipation as well as diffusion processes on the non‐equilibrium activity coefficients of the carbon and oxygen in the molten steel may almost be neglected. Except in the regions where the chemical C‐O reaction takes place (the up‐snorkel zone and the bath in the vacuum vessel), the non‐equilibrium components of the non‐equilibrium activity coefficients of the carbon and oxygen in the molten steel at the other places in the degasser are all tending towards one. The non‐equilibrium effects (mainly, the C‐O reaction itself) give a restraining role on the decarburization of liquid steel in the RH refining process. This model is able to model more reasonably and precisely the non‐equilibrium decarburization process during the vacuum circulation refining of molten steel in comparison to a model without considering the non‐equilibrium effects.     

节能技术在RH真空精炼工艺中的应用

介绍了MFB顶吹氧枪技术、水环真空泵技术和干式机械泵技术等3种节能技术在RH真空精炼工艺的应用。国内某钢厂300 t RH真空精炼系统的应用表明:应用MFB顶吹氧枪技术,RH处理过程钢液温降可减少15.8℃;应用水环真空泵技术,可降低RH吨钢生产成本约2.25元;应用干式机械泵技术,可降低RH吨钢生产成本约6.05元。     

宝钢─炼钢新建2RH真空脱气设施简介

简要说明了宝钢一炼钢新建 2RH真空脱气设施的必要性 ,重点介绍了 2RH采用的顶枪技术、真空系统、纯水闭路循环机械冷却水系统及EIC三电一体化控制系统。新建的 2RH真空脱气设施不仅脱碳、脱氢速度快 ,而且具有化学加热钢水、喷粉脱硫、喂丝吹氩等功能 ,真空槽可保持较高的温度 ,大大减少了槽内结冷钢的可能性     

Mathematical Modelling of Non‐equilibrium Decarburization Process during Vacuum Circulation Refining of Molten Steel: Mathematical Model of the Process

The characteristics of the non‐equilibrium decarburization process during the vacuum circulation (RH) refining of molten steel have been considered and analysed. On the basis of the fundamentals of metallurgical reaction engineering and non‐equilibrium thermodynamics, as well as the two‐fluid model for gas‐liquid two‐phase flow and a modified k‐? model for turbulent flow, a novel three‐dimensional mathematical model for the process has been proposed and developed. The details of the model, including the establishment of the governing equations and the especially modified two‐equation k‐? model, the determination of the appropriate source terms and boundary conditions and others, have been presented. The related parameters of the model have been discussed and determined for the decarburization refining process of molten steel in a 90‐t multifunction RH degasser under RH and RH‐KTB operating conditions.