废气分析在RH脱碳过程中的应用

根据RH废气分析系统对废气流量及其中CO、CO2气体含量的测量,建立了废气分析脱碳数学模型。经验证,模型计算值与实际测量值吻合较好。对于成品碳的质量分数小于等于20×10-6的超低碳钢,模型计算的RH自然脱碳终点碳的质量分数误差在±3×10-6之间。废气流量修正系数δ采用分段取值更能符合实际情况,RH精炼开始3 min内,δ为0.35,3 min后δ为0.6。在RH自然脱碳后期,当废气中CO的质量分数由峰值降低到5%时,钢水中碳的质量分数的平均值达到13×10-6,已经低于RH终点碳含量的要求值,可以判定RH脱碳过程结束。     

超纯铁素体不锈钢VOD脱碳模型研究

摘要：为了实现对超纯铁素体不锈钢VOD精炼脱碳过程的动态即时预测及控制,以酒钢宏兴不锈钢分公司100 t VOD炉冶炼超纯铁素体不锈钢的过程为研究对象,从顶吹氧气的分配行为和C Cr的竞争氧化出发,建立基于炉气分析技术的VOD动态脱碳模型,并在Matlab环境下开发相应的应用软件,得到全过程钢液成分、氧气分配比、温度等参数随时间的变化规律,对不同阶段的临界碳浓度给出估计范围。利用VOD出站成分以及精炼过程中CO/CO2的实际变化规律加以检验,与实际值吻合较好,较好地预测了实际变化趋势。     

VOD冶炼超纯铁素体不锈钢脱碳工艺的研究

针对不锈钢冶炼特点,通过脱碳热力学和动力学分析,研究了VOD精炼工艺参数对超纯铁素体不锈钢脱碳速度和终点碳含量的影响,并进行了大量工业生产试验.结果表明,提高冶炼温度、增加吹氧流量和吹氩流量、降低氧枪的供氧压力和枪位有利于提高脱碳速度,获得更低的终点碳含量.     

VOD炉精炼00Crl8Nil0N碳终点命中率研究及应用

通过热力学、动力学原理分析VOD炉精炼00Crl8Nil0N超低碳不锈钢脱碳命中率的影响因素,优化攀长特炼钢总厂二作业区VOD炉精炼作业过程中的入炉温度、临界碳含量、真空度、吹氩等,同时根据氧电势检测实时数据以及废气温度变化调整真空泵作业模式等措施,多个指标综合监控终点碳,从而提高了碳终点命中率、Cr收得率、缩短了精炼周期、降低了工序生产成本,在超低碳不锈钢生产中取得了较好的冶金效果。     

VOD炉冶炼Cr不锈吹氧脱碳浅析

在采用电弧炉＋VOD＋CC生产Cr不锈连铸坯的生产过程中,VOD精炼的控制对整个生产有着至关重要的作用,而控制Cr不锈VOD精炼过程的关键是吹氧脱碳。在吹氧脱碳过程中,脱碳初期及高碳区、低碳区采用不同的吹氧、吹氩流量及真空度控制,可以提高脱碳速度,同时以氧电势分析仪数据为主,以计算吹氧量、真空度变化、废温变化为辅,能更加准确的控制终点碳,从而提高吹氧脱碳效率。     

基于烟气成分分析的电弧炉炼钢脱碳模型

为了连续地预测电弧炉熔池中碳含量,实现对冶炼终点碳含量的控制,以红外烟气分析技术和物质质量守恒计算为基础,结合入炉总碳量和供氧量等生产数据,建立了电弧炉炼钢脱碳数学模型.对莱芜钢铁股份有限公司特殊钢厂50tUHP电弧炉实际冶炼数据的模拟计算表明,该模型能实现对熔池碳含量的连续预测和终点控制.模拟计算结果还表明,电弧炉冶炼过程中,脱碳速度主要受供氧流量的影响,最大可达0.12%～0.16%min-1.该模型用于电弧炉供氧优化后,氧气消耗明显降低.     

120tAOD全铁水冶炼 400系不锈钢数学模型的应用

针对脱磷铁水+AOD+VOD三步法冶炼400系不锈钢冶炼过程,通过分析AOD炉脱碳保铬化学反应中碳、铬、温度三者之间的平衡关系,并综合考虑体系的质量和热量衡算及精炼过程的不等温状态,开发了基于Visual Basic.Net程序的AOD全铁水冶炼数学模型,可准确计算出入炉料和发热剂的用量,并分析冶炼过程的热量收支情况和影响过程热量的关键因素。与实际生产用料量相比,模型计算值误差均在8%以内,因此可用于指导生产,最终实现钢水高效化冶炼。     

转炉炼钢熔池碳含量动态变化研究

通过引入炉气分析仪采集的实测数据,用碳指数模型描绘熔池内碳含量实时变化趋势,并用修正后的碳积分模型计算转炉吹炼过程的总脱碳量,以对碳含量的动态变化和终点出钢情况做出预报.在机理分析的基础上,利用三阶段脱碳曲线的后期变化趋势建立碳指数实时和终点预报模型,同时对碳积分计算公式加以修正,得到冶炼全程的脱碳率计算模型.仿真结果表明,碳指数及碳积分模型直接用于指导转炉炼钢生产具有一定的参考价值,在一定程度上可以取代炉气分析仪的使用.     

RH MFB精炼过程脱碳数学模型及工艺研究

 为研究RH MFB精炼工艺对脱碳过程的影响，将脱碳机理确定为钢液本体脱碳与CO克服静压力上浮、氩气泡表面脱碳和飞溅液滴脱碳，根据脱碳反应动力学和质量守恒原理建立了RH MFB脱碳数学模型。计算结果表明：降低初始碳含量、增大初始氧含量可使脱碳终点碳含量降低；提高压降速率和吹氩流量、增大浸渍管内径使得脱碳速率增大；在固定氧气流量下，随着吹氧时间的延长，脱碳终点碳含量降低，但脱碳终点氧含量升高。     

电弧炉炼钢全过程钢水碳含量动态预报模型

根据电弧炉物料平衡理论与利用BP神经网络的方法,建立了理论模型结合神经网络的电弧炉炼钢全程钢水碳质量分数实时预测模型。通过模型得出冶炼过程中碳质量分数变化曲线,实现对全程钢水碳质量分数的实时监控。在接近冶炼终点时,由于脱碳反应中碳氧积的存在,因此模型对影响终点碳质量分数的因素进行分析,采用BP神经网络方法进行预测,满足了对电弧炉冶炼终点碳质量分数预报准确度的要求。     

250 t钢包RH精炼脱碳动态控制实践

为了提高RH脱碳效果,缩短RH精炼周期,从热力学和动力学理论上对RH脱碳进行分析,从实践上对RH脱碳处理进行动态控制工艺优化。吹氧加铝升温工艺优化后,超低碳钢成品碳合格率从94%左右提高到100%,RH处理10 min即可把碳脱到0.002%左右,与工艺优化前对比,成品碳质量分数从0.001 5%～0.002%降低到0.001%～0.001 4%。研究了压降对脱碳速率的影响,结果表明,压降速度越快,脱碳速率越高,预抽真空可以提高脱碳效率和获得更低的终点碳含量。研究了脱碳结束时氧含量与脱碳终点碳含量的关系,结果表明,脱碳结束时氧质量分数在0.025%～0.035%范围内,能满足脱碳终点碳质量分数小于0.002%的要求。     

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。     

超低碳烘烤硬化钢固溶碳质量分数控制技术

为了获得具有合适烘烤硬化值(简称BH值)的钢板,烘烤硬化钢冶炼过程中必须控制好固溶碳质量分数。介绍了首钢京唐公司超低碳烘烤硬化钢开发过程中有关固溶碳窄成分(±0.000 3%)的工艺控制技术,稳定控制固溶碳质量分数的关键措施包括:通过控制好精炼脱碳时间来控制精炼结束碳质量分数;使用低碳合金调整钢水合金质量分数以控制脱碳后合金增碳0.000 1%~0.000 2%;使用低碳(w([C])≤0.5%)耐火材料,控制好精炼结束到中间包的增碳。采取措施后,中间包熔炼成分中碳质量分数的稳定性得到大幅提高,固溶碳质量分数w([C])sol偏差±0.000 3%的合格率由66%提高到81%。     

Kinetic Model of Decarburization and Denitrogenation in Vacuum Oxygen Decarburization Process for Ferritic Stainless Steel

The characteristics and classification of decarburization and denitrogenation in the vacuum vessel for stainless steel production are analyzed. Based on the analysis of movements of the liquid steel and bubbles, the kinetics of decarburization and denitrogenation in the vacuum oxygen decarburization (VOD) process has been studied. A kinetic model of decarburization and denitrogenation has been developed to simulate the VOD process, considering each reaction zone as oxygen blowing crater, bottom blowing plume, steel/slag interface, and plume eye. As a result, it is possible to quantify the contribution of each reaction zone in decarburization and denitrogenation rate at a different stage in the VOD process. Specific trials at a vacuum induction furnace were performed to refine stainless steel in vacuum carbon deoxidation (VCD) and VOD style, respectively. The trial results are in good agreement with the model calculation. Combining the trials and the model calculation and the influence of temperature control, critical carbon content selection on the terminal total [C] + [N] content can be discussed further to provide a reasonable proposal for high-quality ferritic stainless steel production. This article is based on a presentation given at the International Symposium on Liquid Metal Processing and Casting (LMPC 2007), which occurred in September 2007 in Nancy, France.     

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.     

Thermodynamic Assessment to Chromium Oxidation in the Production of Stainless Steel

A solution model called ε approach is applied to predict the thermodynamic solution behaviour of Cr in steel melts. The calculated results are supported by the available experimental results. Further predictions on chromium scorification are achieved in view of melting and refining processes for Cr‐containing steels. Chromium reduction from slags after meltdown during EAF melting and AOD or VOD refining treatment is important for the production of Cr‐containing steels. It is thermodynamically predicted that chromium is inevitably oxidized during decarburization process which coincides with the industrial and experimental results. Minimum oxidation of chromium can be reached by lowering the partial pressure of CO gas at high temperatures.     

RH真空精炼控氮工艺实践

为精确控制钢中氮含量,通过对真空条件下钢液控氮的热力学和动力学条件进行分析,结合实际情况,研究120 t RH精炼过程中不同硫质量分数铝镇静钢的脱氮和增氮过程。研究结果表明,不同硫质量分数铝镇静钢在脱氮进行到7 min时都出现脱氮速率拐点,脱氮速率明显降低,拐点处钢水氮质量分数为0.004 1%~0.004 9%;RH精炼过程中切换提升气体为氮气的增氮工艺稳定可行,在提升气体流量为600 L/min条件下,低硫铝镇静钢增氮速率大于高硫铝镇静钢,增氮速率分别为0.000 23%/min和0.000 14%/min。