Coke behavior with H_(2)O in a hydrogen-enriched blast furnace:A review

Hydrogen-enriched blast furnace ironmaking has become an essential route to reduce CO_(2)emissions in the ironmaking process.However,hydrogen-enriched reduction produces large amounts of H_(2)O,which places new demands on coke quality in a blast furnace.In a hydrogen-rich blast furnace,the presence of H_(2)O promotes the solution loss reaction.This result improves the reactivity of coke,which is 20%-30%higher in a pure H_(2)O atmosphere than in a pure CO_(2)atmosphere.The activation energy range is 110-300 kJ/mol between coke and CO_(2)and 80-170 kJ/mol between coke and H_(2)O.CO_(2)and H_(2)O are shown to have different effects on coke degradation mechanisms.This review provides a comprehensive overview of the effect of H_(2)O on the structure and properties of coke.By exploring the interactions between H_(2)O and coke,several unresolved issues in the field requiring further research were identified.This review aims to provide valuable insights into coke behavior in hydrogen-rich environments and promote the further development of hydrogen-rich blast furnace ironmaking processes.

The future of blast furnace ironmaking—a Nordic perspective

The blast furnace is the oldest metallurgical process in commercial use.It has gone through great improvements during the last decades and new important modifications are still foreseen.The huge amount of coal and coke needed for reduction of iron ore is resulting in emissions of carbon dioxide that have to be strongly reduced to meet the requirement of minimizing the carbon footprint.All residuals from iron- and steelmaking also need to be taken care of to meet the requirement of zero waste.This paper deals with several potential improvements of the blast furnace process being developed in the LKAB Experimental Blast Furnace in Lulea, Sweden over the last decade,including operation at ultra low slag volume,injection of BF flue dust,injection of BOF slag,and the oxygen blast furnace.

Numerical Simulation of Innovative Operation of Blast Furnace Based on Multi-Fluid Model

A multi-fluid blast furnace model was simply introduced and was used to simulate several innovative ironmaking operations. The simulation results show that injecting hydrogen bearing materials, especially injecting natural gas and plastics, the hydrogen reduction is enhanced, and the furnace performance is improved simultaneously. Total heat input shows obvious decrease due to the decrease of heat consumption in direct reduction, solution loss and silicon transfer reactions. If carbon composite agglomerates are charged into the furnace, the temperature of thermal reserve zone will obviously decrease, and the reduction of iron-bearing burden materials will be retarded. However, the efficiency of blast furnace is improved just due to the decrease in heat requirements for solution loss, sinter reduction, and silicon transfer reactions, and less heat loss through top gas and furnace wall. Finally, the model is used to investigate the performance of blast furnace under the condition of top gas recycling together with plastics injection, cold oxygen blasting and carbon composite agglomerate charging. The lower furnace temperature, extremely accelerated reduction rate, drastically decreased CO2 emission and remarkably enhanced heat efficiency were obtained by using the innovative operations, and the blast furnace operation with superhigh efficiency can be realized.

A mathematical model capable of describing the liquid flow mainly in a blast furnace

The molten liquid flow inside a packed bed is a familiar momentum transportation phenomenon in a blast furnace. With regard to the reported mathematical models describing the liquid flow within a packed bed, there are some obstacles for their application in engineering design, or some limitations in the model itself. To overcome these problems, the forces from the packed bed to the liquid flow were divided into appropriate body and surface forces on the basis of three assumptions. Consequently, a new mathematical model was built to present the liquid flow inside the coke bed in a blast furnace. The mathematical model can predict the distribution of liquid flowrate and the liquid flowing range inside the packed bed at any time. The predicted results of this model accord well with the experimental data. The model will be applied considerably better in the simulation on the ironmaking process compared with the existent models.

Heat distribution model under hydrogen-rich low-carbon conditions in blast furnace

Low carbon development of blast furnaces is one of the key technological directions in the current development of ironmaking.Owing to the differences in the physical and chemical properties of hydrogen and carbon,hydrogen-rich media entering a blast furnace will change the heat distribution,thus affecting the stability of production.Accordingly,a heat distribution model was proposed to study the temperature distribution in a blast furnace,simultaneously considering gas-solid heat exchange,slag and iron melting,and chemical reactions.The model was used to analyze the temperature distribution of a 2300 m^(3) blast furnace and was verified via comparison with actual production data.Subsequently,the effects of the injection rate of hydrogen-rich media,H2 concentration,and oxygen enrichment rate of the blast on the temperature distribution were investigated.Results indicated that the increase in the injection rate of the hydrogen-rich media decreased the amount of direct reduction and led to an increase in the furnace temperature.Furthermore,an increase in the oxygen enrichment rate led to a decrease in the furnace temperature,but could reduce the solid fuel ratio,while the change in H2 concentration had less effect on the temperature distribution.The combination of hydrogen-rich media injection and the increase in the oxygen enrichment rate would help to adjust the temperature distribution to the same level as the conventional blast furnace conditions.

Effect of nut coke on the reduction behavior in iron-making blast furnace

Ore-coke mixed charging is a potential technique for optimizing the charging pattern. Recently, the charging of small-sized coke（ nut coke） with the ferrous burden layer has been applied to reduce raw material usage and decrease costs. Various studies indicate that mixing nut coke with ferrous burden can enhance the reduction kinetics,improve the softening and melting properties, and have a positive effect on the permeability. Although mixed charging, especially the addition of nut coke to the burden layer, has been used in the industry for various reasons ,the mechanisms and side effects for using nut coke are not well understood, and the mixing ratio remains limited in actual blast furnace operation. High-temperature experimental studies were conducted to increase the understanding of the complex process of reduction, softening and melting properties, and permeability in a blast furnace when mixing nut coke with an ore layer. The effect of the nut coke mixing ratio and nut coke size was investigated under various reducing conditions. To describe the reduction processes of burden materials, numerous experiments were interrupted at different stages of the reduction, and the collected materials were examined by using image analysis. The reduction degree of mixed charging（iron ore mixing with nut coke） was improved when using nut coke at the temperatures of 800 ℃ and above. The reaction rate of ore-nut coke mixed charging was higher than that of standard charging without the use of nut coke.

Data-driven soft sensors in blast furnace ironmaking:a survey

The blast furnace is a highly energy-intensive,highly polluting,and extremely complex reactor in the ironmaking process.Soft sensors are a key technology for predicting molten iron quality indices reflecting blast furnace energy consumption and operation stability,and play an important role in saving energy,reducing emissions,improving product quality,and producing economic benefits.With the advancement of the Internet of Things,big data,and artificial intelligence,data-driven soft sensors in blast furnace ironmaking processes have attracted increasing attention from researchers,but there has been no systematic review of the data-driven soft sensors in the blast furnace ironmaking process.This review covers the state-of-the-art studies of data-driven soft sensors technologies in the blast furnace ironmaking process.Specifically,wefirst conduct a comprehensive overview of various data-driven soft sensor modeling methods(multiscale methods,adaptive methods,deep learning,etc.)used in blast furnace ironmaking.Second,the important applications of data-driven soft sensors in blast furnace ironmaking(silicon content,molten iron temperature,gas utilization rate,etc.)are classified.Finally,the potential challenges and future development trends of data-driven soft sensors in blast furnace ironmaking applications are discussed,including digital twin,multi-source data fusion,and carbon peaking and carbon neutrality.

高炉鼓风条件对回旋区形态影响的数值模拟研究

针对高炉回旋区难以实验观测,研发了二维欧拉—颗粒多相流动模型,对高炉回旋区形成进行了数值模拟,研究了鼓风速度、鼓风角度对回旋区尺寸和形状的具体影响。研究结果表明,当鼓风速度从150 m/s增至250 m/s时,回旋区气相体积分数及尺寸显著增加,深度和高度分别从0.75 m和1.24 m扩展至1.4 m和2.36 m。另外,鼓风角度的调整在回旋区的水平和深度方向同样起到了关键作用,当鼓风角度从0°调整至-30°时,回旋区高度保持在2 m左右,深度从1.52 m降至1.13 m,特别是较小鼓风角度有利于增加回旋区深度。研究结果为高炉鼓风操作参数优化提供了科学依据,对于提升高炉运行效率和生产能力具有重要的指导价值。

碳中和背景下我国低碳炼铁技术发展现状与前景

我国钢铁生产工艺长期以“高炉—转炉”长流程为主,能源结构高碳化特征明显。作为钢铁流程中的碳排放大户,炼铁系统深度减碳成为我国钢铁行业实现碳中和目标的关键。本文分别从高炉炼铁和非高炉炼铁两个角度出发,梳理总结了各主要低碳炼铁工艺技术的研究进展和主要问题,并对其应用前景进行了展望。我国钢铁工业应把技术创新作为降碳的核心要素,结合行业发展趋势和自身特点,加大力度开发适合我国国情的低碳炼铁新技术;综合考虑资产保值、技术成熟程度和降碳潜力,短期内应以基于现有高炉工艺的深度脱碳技术创新为主要方向,从而为远期零碳钢铁的发展提供过渡方案和缓冲空间;中长期以富氢气基竖炉直接还原技术为发展重点,不断提升其技术成熟度和经济适用性,逐步提高氢气比例直至全氢冶炼;氢基熔融还原技术和电解还原铁技术的发展任重道远,未来有望成为实现我国钢铁行业碳中和目标的解决方案之一。

生物炭替代煤粉/焦炭高炉炼铁碳减排技术研究进展

钢铁行业是能源消耗和碳排放大户,因此在碳中和背景下寻求可替代传统煤的零碳原料是钢铁行业重点发展的碳减排技术。生物炭具有碳中性特征,碳含量和热值与煤接近,是煤粉和焦炭理想的替代原料。本文系统介绍了生物炭在炼焦、烧结、高炉炼铁中的潜在利用途径,并进一步聚焦生物炭应用于高炉炼铁时所需具备的理化特性,阐述了生物炭碱金属、强度、粒度与比表面积在替煤代焦时的影响及机理。针对碱金属降低焦炭强度等问题,介绍了酸洗等脱矿方法降低生物炭碱金属含量;针对生物炭机械强度差难以入炉问题,总结了焦炭强度形成机理和生物炭成型增强工艺;针对生物炭导致炼焦煤混合物流动性变差问题,通过调控生物炭粒度和比表面积以降低对焦炭的负面影响。最后,总结了生物炭替代煤粉和焦炭高炉炼铁的国内外进展及预期CO_(2)减排效果。通过分析生物炭替煤代焦目前工业应用中存在的挑战以及生命周期评价的相关研究情况,为未来钢铁行业实现碳中和提供技术支撑。

基于知识与数据相结合的高炉炉温融合预测

针对复杂高炉冶炼过程具有大滞后等特点,为提高高炉炉温预测精度,提出一种经验知识与数据相结合的炉温融合预测方法。首先,根据高炉经验知识,分析各变量在高炉内的滞后关系,以及在滞后时间内停留在高炉内部形成的累积关系,累积量对当前炉温造成的影响。通过累积量进行相关性分析,合理地确定输入变量。然后,将铁水温度与铁水硅含量融合来更好地表征炉温。最后,通过神经网络利用累积量作为输入建立经验知识与数据相结合的高炉炉温融合预测模型。实验中使用某钢厂高炉生产数据进行仿真,结果表明累积量模型具有良好的性能,可为高炉炉温预测提供新思路。

不同条件下焦炭的高温反应行为及热态性能评价

针对某钢铁企业四种捣固焦,研究了不同条件下焦炭高温气化反应行为,从不同角度评价焦炭热态性能。结果表明,在国标条件下,四种焦炭的CRI和CSR分别在21%~31%和54%~68%范围内。随着焦炭反应性的升高,气化溶损反应开始温度和激烈温度均降低,且两者分别在887~948℃和1315~1423℃范围内。随着溶损率的增加,焦炭C和D的固定溶损率反应后强度均降低,且前者大于后者,但两者差值明显低于国标条件下的差值。高炉实际运行结果显示,在其他条件不变的情况下,使用焦炭C和D时高炉技术经济指标相差不大。采用高温下固定溶损率反应后强度和平均反应速率评价焦炭的热态性能更符合炉内情况,推荐的检测条件为温度1200~1400℃、固定溶损率为20%~30%。

梅钢5号高炉炉墙结厚的原因及炉况恢复

对梅钢5号高炉炉墙结厚的原因及炉况恢复进行了总结。5号高炉开炉以来首次炉墙结厚,主要征兆是全炉水温差下降和炉身静压力曲线值出现偏差。结厚的主要原因:一是焦炭质量劣化,入炉焦炭CRI最高上升至23.6%左右,灰分在12.5%左右;二是烧结矿质量劣化,品位降至57.0%左右,FeO含量降至8.5%左右;三是炉渣(Al_(2)0_(3))最高上升至19.0%左右;四是入炉有害元素含量超标,锌负荷升至0.36 kg/t,碱金属负荷最高上升至3.0 kg/t;五是炉况持续恶化。通过采取发展边沿气流、提高入炉风量、提高炉温加锰矿洗炉等措施,炉况得到恢复。

高炉炼铁中数据驱动建模及生产智能化升级分析

针对数据驱动建模的应用效果较差,炼铁平台缺乏数字化的问题,提出了局部感知增强的特征、时间注意力模型,优化了数据驱动建模,具有良好的铁水硅含量预测效果,对工业互联网平台架构进行分析,借助工业平台智能化的升级,可保障炼铁过程更高效平稳的进行,以期促进钢厂的发展。

熔融还原炼铁工艺用耐火材料的研究进展

相较于高炉炼铁工艺,HIsmelt和Corex两种熔融还原炼铁工艺几乎不使用焦炭,且资源利用效率高,环保优势突出,但这两个工艺的熔渣中FeO含量普遍偏高,且技术成熟度和炉内反应机制的深入了解仍然不足,导致熔融还原炉的寿命普遍低于高炉的。分析了HIsmelt和Corex两大工艺的流程特点,总结了HIsmelt和Corex工艺用耐火材料的材料选择、维护和性能优化等方面的研究现状,指出了熔融还原炼铁工艺用耐火材料存在的问题及改进方向。

昆钢2号高炉炉况失常的原因及处理措施

对昆钢2号高炉2023年4月8日发生的炉况失常的原因及处理措施进行分析总结。认为这次炉况失常的直接原因是风口小套长时间漏水和炉墙黏结,间接原因是高炉计划检修周期过长、烧结矿冶金性能劣化、熔剂质量波动造成渣相波动和炉顶洒水效果不好。从装料制度、送风制度、造渣制度、热制度等方面进行系统调整,主要通过采取缩矿批退负荷、集中加焦、调整布料矩阵、增加水量提高冷却强度等措施,炉况实现快速恢复。4月12日,2号高炉焦炭负荷提升至4.54,日产量恢复到7058.789t/d,燃料比稳定在516kg/t。

首钢股份2号高炉炉墙结厚的成因及处理

首钢股份2号高炉因原燃料质量变差、抗原料质量波动能力差、操作应对不及时等原因导致炉墙结厚,炉况波动时间较长。通过采取减轻焦炭负荷、调整装料制度、降低炉渣碱度、使用萤石洗炉、更换风口等措施进行处理,炉况恢复正常。认为:①当进厂焦炭质量不达标时,应及时向上反馈,以免造成生产困难;②在原燃料质量稳定性较差的条件下,应保持煤气流通路,重视中心气流的作用,提高抗外围原燃料质量波动的能力;③针对原燃料条件及其质量波动,应及时修改、制订调整措施,保证高炉顺行。

高炉炉墙结厚机理探究

高炉生产过程中存在多种因素造成高炉炉墙结厚,当结厚发生时高炉各操作参数及炉况顺行也会发生变化。对高炉炉墙结厚机理进行探究,通过确定结厚的位置,计算黏结物厚度,采取热洗、炸瘤等方式来消除高炉结厚,从而实现高炉炉况稳定顺行,不断改善高炉技术经济指标。

我国非高炉炼铁的现状与发展

介绍了非高炉炼铁的发展现状,并对非高炉炼铁的主要工艺进行了说明,包括直接还原法和熔融还原法。重点对回转窑工艺、竖炉工艺、COREX工艺、FINEX工艺进行了详细的介绍,指出非高炉炼铁技术在资源利用效率、环境友好性、产业发展潜力等方面具有广阔的发展前景。

韶钢8号高炉计划检修延时复风操作实践

韶钢8号3 200 m^(3)高炉计划定修28 h,主控项目更换4号热风阀,受拆除热风阀法兰处耐衬的影响,热风阀拆除难度较大,导致高炉延迟复风18 h,针对此制订了详细的复风方案,通过精心组织高炉操作,确保了复风的整体顺利进行,也验证了韶钢炼铁厂针对异常情况的快速应对能力,杜绝了工艺事故的发生,实现了炉况快速安全恢复。