基于转炉烟气分析的熔池碳含量及温度动态预报

基于烟气分析获得烟气流量及成分,应用碳平衡原理构建的碳积分数学模型可动态预测熔池中的碳含量;对炉气信息延迟性、炉气量、枪位系数和脱碳速率拐点a与b等参数的修正,能够提高熔池碳含量动态预报的精度。在熔池碳含量动态预报的基础上,基于热平衡理论和碳氧反应热力学构建了熔池温度动态预报模型,通过脱碳速率拐点a和b的修正以及分阶段模型的构建,能够提高熔池温度的预报精度。在此基础上采用Visual Basic 6.0和SQL Server 2000数据库构建了熔池碳含量和温度动态预报系统,利用该系统对一定时期的46炉冶炼数据进行了离线运行,结果表明:终点w(C)0.2%时,预报偏差小于0.02%命中率为84.8%,模型终点温度预报偏差小于20℃命中率为84.8%,C-T双命中率达到73.9%,基本满足冶炼对终点命中率的要求。     

基于炉气分析的熔池碳含量及温度变化研究

 根据物料平衡及反应平衡原理，利用炉气分析系统在线连续检测、分析数据，建立了转炉冶炼过程中碳含量及温度变化的动态模型。该模型计算结果与检测结果吻合较好，这表明：①通过烟气流量、成分及铁水质量和初始碳含量可动态地确定熔池中的碳含量；②以动态确定的碳含量为基础，结合炉气分析数据，再经热力学平衡分析，可预测熔池温度的动态变化。     

转炉炉气分析技术在本钢的初步应用

结合本钢炉气分析在线系统,建立了应用物料平衡原理预测碳含量及根据反应平衡原理预测温度变化的转炉动态模型.模型预测结果表明:熔池中的碳含量是炉气流量及CO和CO2分压的函数,其中初始碳含量的准确程度对模型的最终预测结果影响最大.熔池温度是碳含量及炉气中CO和CO2分压的函数,其中吹炼过程的平稳性是模型最终预测结果准确获得的保证.并应用本模型对1 530炉次的历史炉气数据进行了离线分析与终点检测结果的比较,收到预期效果.     

应用炉气分析的转炉动态模型初步研究

运用物料平衡及反应平衡原理,利用炉气连续分析的数据,建立了转炉冶炼过程的动态模型.本模型的计算结果表明:(1)通过烟气流量、成分及原料中初始碳含量可动态地确定熔池中的碳含量;(2)以动态确定的碳含量为基础,经过热力学平衡分析,可确定熔池内温度及氧含量的动态变化.     

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.     

基于函数型数字孪生模型的转炉炼钢终点碳控制技术

由于转炉冶炼过程中的热力学和动力学反应复杂,副枪控制模型和传统的烟气分析模型存在很大的局限性,导致了转炉冶炼终点碳含量的预测精度偏低,是实现智能炼钢的主要技术瓶颈. 针对上述问题,提出了基于烟气分析的炼钢过程函数型数字孪生模型. 首先,利用烟气分析得到连续监测的实时数据,以此来实时监控转炉熔池内钢水的碳氧反应状态; 然后,根据熔池反应所处的不同阶段,利用函数型数据分析方法建立吹炼前期和吹炼后期的函数型预测模型; 在此基础上,按照吹炼前期和吹炼后期这两个阶段来分别自动修正模型中的系数函数,从而能在复杂的实际工况条件下完成对熔池碳含量的准确预测. 通过260 t氧气转炉的工业应用实例,证实函数型数字孪生模型具有良好的自学习和自适应能力,对异常冶炼状态具有良好的鲁棒性,可以实现全过程的熔池碳含量动态预测,终点碳质量分数在± 0. 02% 范围内的命中率为95%. 利用函数型数字孪生模型在拉碳阶段对钢水中碳含量的预测值来控制终吹点. 更为重要的是,在保证入炉原料成分、温度、质量等参数稳定的前提下,采用该模型可以有望取消基于副枪的停吹取样步骤,从而降低生产成本,提高产品质量和生产效率,具有广泛的工业应用前景.      

转炉炼钢动态过程控制量算法的改进

介绍了转炉炼钢动态过程控制量（氧气补吹量和冷却剂量）的计算、熔池成分和温度预报的计算过程，以及动态模型系数的学习算法。通过对动态过程量算法的改进，模型命中率由45．2％提高到91．9％，取得了明显的效果。     

基于炉口火焰多光谱分析技术预报转炉终点碳的研究

利用多光谱复合分析技术,设计开发了远距离、非接触式转炉炉口火焰碳谱线分析技术和装置,预报转炉熔池钢液碳含量。该技术通过分析转炉主吹过程炉口火焰碳谱线的变化规律,找出了炉口火焰多光谱光强分布图样与转炉熔池钢液碳含量的对应关系,建立了转炉冶炼过程熔池碳含量的实时预报模型。该装置在某钢厂70t转炉上进行了试验,按照终点[C]≤0.05%±0.02%、0.05%~0.15%±0.03%和0.15%±0.05%三个范围内预报精度,预报命中率分别为83.8%、80.1%和85.6%,研究表明,转炉冶炼过程的装入制度、造渣制度以及供氧制度对终点碳预报基本没有影响。     

在安塞乐米塔尔印第安纳海港第二炼钢厂BOF车间没有底吹和抑制罩燃烧系统采用炉气分析预测碳模型

炼钢车间可以利用炉报分析仪以及BOF工艺过程得到的数据模拟终点熔池碳含量。该文分享了开发在BOF中预测碳模型，没有底吹／底搅拌能力以及此模型面对的挑战和极限。     

基于炉气分析熔池碳含量的在线测量

采用飞行质谱技术构造的炉气分析系统,依据质量平衡原理,结合炉气流量计测得的炉气流量,计算出了熔池的瞬时脱碳速度,采用碳积分模型或者碳曲线拟合模型预测计算熔池中的碳含量,为解决熔池碳含量在线测量分析技术的难题提供参考.     

基于炉气非灰辐射特性的钢坯表面热流研究

 基于加热炉内炉气的非灰辐射特性,指出三元辐射体系(炉气 炉壁 钢坯表面)中炉气存在2种发射率和6种吸收率。应用射线跟踪方法推导钢坯表面热流表达式,解除了Τимофеев公式中炉壁为零热流和炉气为灰体的限制。以某轧钢厂的一座步进梁式加热炉为例,对其钢坯表面热流进行了模拟计算。推导的钢坯表面热流表达式为加热炉在线控制数学模型中钢坯表面热流的简化算法提供了理论依据。此外,给出了炉气为非灰时的辐射全交换面积的一种计算方法,为准确求解加热炉炉膛内的辐射热交换创造了条件。     

Radiative heat transfer in rotary kilns

Radiative heat transfer between a nongray freeboard gas and the interior surfaces of a rotary kiln has been studied by evaluating the fundamental radiative exchange integrals using numerical methods. Direct gas-to-surface exchange, reflection of the gas radiation by the kiln wall, and kiln wall-to-solids exchange have been considered. Graphical representations of the results have been developed which facilitate the determination of the gas mean beamlength and the total heat flux to the wall and to the solids. These charts can be used to account for both kiln size and solids fill ratio as well as composition and temperature of the gas. Calculations using these charts and an equimolar CO₂−H₂O mixture at 1110 K indicate that gas-to-surface exchange is a very localized phenomenon. Radiation to a surface element from gas more than half a kiln diameter away is quite small and, as a result, even large axial gas temperature gradients have a negligible effect on total heat flux. Results are also presented which show that the radiant energy either reflected or emitted by a surface element is limited to regions less than 0.75 kiln diameters away. The radiative exchange integrals have been used, together with a modified reflection method, to develop a model for the net heat flux to the solids and to the kiln wall from a nongray gas. This model is compared to a simple resistive network/gray-gas model and it is shown that substantial errors may be incurred by the use of the simple models.     

加焦方式对气化炉炉料结构和气流分布的影响

装料模式决定了料床的孔隙度结构,进而决定了煤气流的分布信息。建立了气化炉炉料结构的离散单元模型和煤气流动的多孔介质模型,以自编程和软件Fluent为载体,结合两个模型共同描述了不同加焦方式对气化炉的炉料结构和煤气流动带来的变化,获得了炉内炉料结构的孔隙度分布信息和煤气的速度场、流线和质量通量。结果表明：首先,由离散单元模型获得的炉料结构信息可作为气流分布模型的边界条件输入;其次,煤气流模型的模拟结果表明焦柱的加入会在加焦位置处形成煤气发展通路,进而改善气化炉透气性,但应控制焦炭加入量,避免气流过度发展,进而影响煤气利用率。通过模拟计算获得的非均匀床层气体流动规律的认识对气化炉加焦工艺有借鉴意义。     

静磁场控制板坯连铸结晶器液面波动

 用Pb Sn Bi低熔点合金进行了热模拟实验,研究了在静磁场作用下板坯连铸结晶器内的液面波动行为。实验结果表明可应用静磁场控制结晶器内金属液面的波动,且磁场对表面波动的抑制作用有一最佳值,即磁感应强度为05 T时液面平均波动最小。为此,为了减少由于液面波动引起的连铸板坯中的卷渣缺陷,有必要在一定的浇铸条件下优化磁感应强度。吹入氩气加剧了表面波动,且随着氩气流量的增加扰动加大。施加电磁制动能够使吹入氩气引起的液面波动受到显著的抑制。     

1420mm冷轧连续退火机组加热炉煤气流量控制解析

介绍了宝钢1420mm冷轧连续退火机组加热炉混合煤气燃烧的控制原理以及混合煤气流量CPU模型的控制流程,同时介绍了加热炉的动态工艺特性和混合煤气流量最佳控制策略.     

Measurements, simulations, and analyses of instantaneous heat fluxes from solidifying steels to the surfaces of twin roll casters and of aluminum to plasma-coated metal substrates

Using implanted thermocouples, and an inverse heat-transfer technique, heat fluxes and associated heat-transfer coefficients during the solidification of steel in a pilot scale 0.6-m-diameter twin roll caster, whose copper contact surfaces had been treated with a propriety coating, were measured. It was found that heat fluxes during initial contact of liquid steel with the rolls were low, rising to maximum values of about 5 to 6 MW per square meter halfway down the sump of liquid steel, but then diminishing toward zero as the strip approached the roll nip. These results corresponded to roll speeds of some 7 m/min, strip thicknesses of 7 mm, and a roll separating force of 20 kN. For higher speeds and thinner strip, a secondary peak in the heat flux was observed. Associated microstructures revealed acicular ferrite, large prior austenite grains, and secondary dendrite arm spacings in keeping with measurements. In parallel experiments simulating a single belt horizontal caster, heat fluxes from strips of various aluminum alloys to coated and uncoated steel and copper substrates were measured. Under these conditions, peak heat fluxes were recorded during the period of initial contact, and depending on the coating characteristics, these reduced to a lower plateau before declining, or continuously decreased toward zero, corresponding to complete solidification of the strip. A theoretical analysis of the maximum heat-transfer rates that can be expected given perfect thermal contact of metal with the rolls, and its moderations by gas films, and substrate coatings illustrates the dominant role of the gas film and the need for dynamic heat flux measurements for quantitative modeling of fluid flows and solidification phenomena in thin strip casting operations. A model for air gap formation is proposed, based on viscous laminar flows within the gas films. Predicted thicknesses are in reasonable accord with those deduced on the basis of heat flux measurements. This article is based on a presentation made in the “Geoffrey Belton Memorial Symposium,” held in January 2000, in Sydney, Australia, under the joint sponsorship of ISS and TMS.     

Fluid Flow and Heat Transfer in the Ladle during Teeming

A two dimensional axisymmetric model was developed to predict the heat flux in a steelmaking ladle during the teeming process. The model predicts dynamically the flow fields in both liquid phase and gas phase along with the movement of the liquid upper surface. The model also predicts the temperature distributions in the liquid metal, gas phase and all layers in the ladle wall. Industrial measurements using infrared radiation camera inside the ladle after teeming and at the wall outside the ladle during the whole process were carried out. The model predictions were found to be in agreement with the measured data. It was found that the heat transfer to the surrounding atmosphere and the conductivity of the highly insulating layer were the most important factors for the heat loss. The decrease of the thickness of the working lining was found to have limited effect on the total heat flux.     

宝钢一高炉料钟布料模型的研究和应用

高炉炉喉料面形状对高炉煤气流分布有着重要影响,因此调整炉顶布料参数并控制料面形状是调节高炉煤气流分布的重要措施.文章介绍了宝钢股份公司一高炉炉顶布料模型的主要试验和理论基础,展示了模型的主要显示界面和布料参数,并分析了该模型的一些使用效果.     

Heat transfer in a direct-fired rotary kiln: II. Heat flow results and their interpretation

Heat flow rates from the gas to the wall and to the bed have been derived from temperature profiles measured in the UBC pilot rotary kiln. The experimental gas-to-wall heat flux has been found to agree closely with theoretical predictions based on a simple radiative model consisting of a grey gas surrounded by a grey surface at uniform temperature. Under identical conditions, the gas-to-solids heat flux is up to ten fold greater than the heat flux between the gas and wall. The gas-to-solids heat flux is a function of the solids feed rate at low throughputs but is constant at higher throughputs. At the lowest feed rates and corresponding rotation speeds heat flow to the bed is limited by mixing of the solids. Heat transfer control changes to the gas side of the bed at higher feed rates and rotation speeds. Under the latter conditions convection appears to account for the major fraction of heat flow to the bed. The heat flow measurements relate directly to observations of the bed motion which can be conveniently characterized by a “bed behavior” diagram. The low heat flux to the bed at low feed rates is due to a slumping action at the surface and concomitant poor mixing. The high heat flux obtained at high feed rates coincides with the observation of a rolling bed. Burden-side and gas-side convective heat transfer coefficients, calculated from the heat flux data, have values ranging from 700 to 1200 and 120 to 240 w/m²K respectively.     

Mathematical modeling of postcombustion in a KOBM converter

A mathematical model has been developed to describe gas flow, combustion reactions, and heat transfer in converter-type steelmaking processes. Thek- ε two-equation turbulent model, a finite reaction model, and the DeMarco-Lockwood flux model have been incorporated in this model to deal with the turbulent flow, postcombustion reactions, and radiation heat transfer. Local gaseous flow patterns, temperature, and heat flux distributions were calculated for a 300 tonne Klöckner Oxygen Blowing Maximillanshuette (KOBM) converter. Comparison between the heattransfer fluxes calculated based on the model and those measured industrially indicates the validity of the model in this application. The postcombustion has been found to be determined by the decarburization rate (DCR) which is directly related to the hardness of blowing not by the entrainment of surrounding gas to the oxygen jet as previously reported. The model revealed that about 20 pct of what is normally considered to be recovered heat has actually been lost through the vessel wall and to the lance. It is shown that this model is useful in studying the detailed mechanisms of postcombustion to optimize operations in converter-type steelmaking processes.