Gas-Particle Flow and Combustion Characteristics of Pulverized Coal Injection in Blast Furnace Raceway

The two-dimensional steady-state discrete phase mathematical model is developed to analyze gas-particle flow and combustion characteristics of coal particles, as well as components concentration and temperature distribu- tion of coal gas in the process of pulverized coal injection of blast furnace raceway. The results show that a great deal of coal gas discharges on the top of raceway away from the tuyere, and the residence time of coal particles in the re- gion of blowpipe and tuyere is 20 ms or so and 50 ms when it reaches raceway boundary. The pressure is the highest at the bottom of raceway and the maximal temperature is about 2 423 K. The char combustion is mainly carried out in the raceway and the maximum of char burn-out rate attains 3× 10-4 kg/s.

Extracting the core indicators of pulverized coal for blast furnace injection based on principal component analysis

An updated approach to refining the core indicators of pulverized coal used for blast furnace injection based on principal component analysis is proposed in view of the disadvantages of the existing performance indicator system of pulverized coal used in blast furnaces. This presented method takes into account all the performance indicators of pulverized coal injection, including calorific value, igniting point, combustibility, reactivity, flowability, grindability, etc. Four core indicators of pulverized coal injection are selected and studied by using principal component analysis, namely, comprehensive combustibility, comprehensive reactivity, comprehensive flowability, and comprehensive grindability. The newly established core index system is not only beneficial to narrowing down current evaluation indices but also effective to avoid previous overlapping problems among indicators by mutually independent index design. Furthermore, a comprehensive property indicator is introduced on the basis of the four core indicators, and the injection properties of pulverized coal can be overall evaluated.

A novel model for cost performance evaluation of pulverized coal injected into blast furnace based on effective calorific value

The combustion process of pulverized coal injected into blast furnace involves a lot of physical and chemical reactions. Based on the combustion behaviors of pulverized coal, the conception of coal effective calorific value representing the actual thermal energy provided for blast furnace was proposed. A cost performance evaluation model of coal injection was built up for the optimal selection of various kinds of coal based on effective calorific value. The model contains two indicators: coal effective calorific value which has eight sub-indicators and coal injection cost which includes four sub-indicators. In addition, the calculation principle and application of cost performance evaluation model in a Chinese large-scale iron and steel company were comprehensively introduced. The evaluation results finally confirm that this novel model is of great significance to the optimal selection of blast furnace pulverized coal.

3D model study of coal/coke combustion in a blast furnace effects of coal properties

A three-dimensional mathematical model of the combustion of pulverized coal and coke has been developed.The model is applied to the blowpipe-tuyere-raceway-coke bed region in an ironmaking blast furnace in one computational domain,which includes two parts:pulverized coal combustion model in the blowpipe-tuyere-raceway cavity and the coal/coke combustion model in the surrounding coke bed.The effects of coal properties are examined comprehensively,in terms of coal burnout and gas species distributions.The results indicate that using a coal of fine particle size or high VM content could improve burnout and would affect the gas composition considerably.The burnout is examined in two ways:compared with burnout along tuyere axis,burnout over the raceway surface is a more sensitive and sensible parameter to describe the amount of unburnt char entering the coke bed.The model is useful for examining the flow-thermo-chemical characteristics of the pulverized coal injection (PCI) process under various conditions in a blast furnace.

The Advancement in Intensified Smelting Technology of Baosteel Blast Furnace

Baosteel always aims at becoming one of the most profitable enterprises in the world, enjoying international competence, benchmarking with the world advanced level,pursuing innovation sustainable development. Recent years, Baosteel Iron-making Department has caught the opportunity of increasing steel demand; conquering disadvantages such as changeable up-stream market, fuel and raw material’s tight supplies and lower quality, etc. In our department, Major technical problems have been overcome, blast furnace intensified smelting technology improved, the cost of molten iron under control, blast furnace long-life span control technology made breakthrough, and Baosteel’s ironmaking capacity improved further.

Comparison of semi-coke with traditional pulverized coal injection and iron ore sintering fuels based on chemical structure and combustion behavior

Substantial semi-coke has been produced through the industrialized low-temperature pyrolysis process,which has great potential as an alternative fuel for pulverized coal injection(PCI)and iron ore sintering.X-ray diffraction,Raman spectroscope,and thermal analysis were used to compare the carbon chemical structure and combustion reactivity of semi-coke,pulverized coal,and coke breeze.The results show that the average volatile matter content in 46 types of semi-cokes is 8.94 wt.%.The fluctuation range of the characteristic parameters of the semi-coke chemical structure is d_(002)=(0.352–0.379)nm and A_(D1)/A_(G)=(2.51–7.92),while the fluctuation range of the characteristic parameters of pulverized coal is d_(002)=(0.348–0.373)nm and A_(D1)/A_(G)=(1.71–9.03)(where d_(002)means the interlayer spacing between the aromatic planes,and A_(D1)/A_(G)is an index that characterizes the degree of disorder of the char structure through the area ratio of the defect peak band D1 to the perfect graphite peak band G);the overlap between these ranges is relatively high.Contrarily,the fluctuation range of the characteristic parameters of coke breeze is d_(002)=(0.343–0.350)nm and A_(D1)/A_(G)=(0.75–2.51),which is markedly different from that of semi-coke.Semi-coke combustion reactivity is close to that of pulverized coal,but considerably better than that of coke breeze.In terms of chemical structure and combustion reactivity,semi-coke can be used as an alternative fuel for PCI;however,when used for sintering alternative fuel,matching of the heat supply and demand in the later sintering stage must be scrupulously analyzed.

Properties and Structural Optimization of Pulverized Coal for Blast Furnace Injection

The properties of mixed coals were studied on the basis of known various properties of the injecting coals in the treatise.The structure of the injecting coals was optimized and put into practical application.It was found that the ignition point was lowered with mixed coals,however,both combustibility and grindability were improved,and explosibility of the mixed coals were decreased as well.Hence,mixed coals injection not only can improve the amount of the injecting coals greatly,but also improve the economical and technical indexes of the blast furnace.

包钢高炉喷吹煤粉利用率的测定

利用透射光偏光显微镜,对包钢高炉重力除尘灰、旋风除尘灰和布袋除尘灰中的碳素种类进行定性和定量分析,以测定高炉喷吹煤粉利用率。测定结果表明,3号高炉喷吹煤粉利用率上下限分别为89.03%和79.46%,4号高炉的喷吹煤粉利用率上下限分别为91.51%和84.14%。认为,3号高炉和4号高炉所使用喷吹煤粉来自同一系列,因此可以通过采取稳定煤粉粒度波动、优化富氧鼓风和提高入炉焦炭强度等措施,来提高喷吹煤粉利用率。

国内某高炉喷吹煤粉的性能评价

高炉喷吹煤粉的优点主要包括显著降低炼铁焦比及生产成本、有效调节高炉热制度、喷吹煤粉反应过程中提高煤气的穿透扩散能力和还原能力、缓解焦煤需求量、减少炼焦投资和环境污染等。为进一步优化高炉喷吹燃料结构和降低炼铁成本,文章对国内某高炉喷吹使用的煤粉的煤质特性进行了深入研究。结果表明:1#煤为烟煤,固定碳含量低、挥发分高,氢元素含量在所试验煤粉中最高,灰分中的CaO和MgO的含量之和最高,超过24%;其他煤种为无烟煤;4#煤的可磨性指数低于40;需要控制其在混煤中的配比。

Interaction mechanism between coal combustion products and coke in raceway of blast furnaces

The interaction mechanism between the combustion products of pulverized coal injected and coke in the raceway of blast furnace was studied through thermodynamic calculation and experiments.The results indicated that additives significantly affected the melting property of coal ash in high temperature zone.Although the unburnt char,raw coal ash,and catalyzed coal ash failed to wet the coke surface,the wettability of the catalyzed coal ash on the coke was greater than that of the raw coal ash.Since the unburnt char had weak reaction with the coke surface,it showed little influence on the surface morphology of the coke.The interaction between the raw coal ash and the coke gave rise to the increase in the pore size on the coke surface.However,the raw coal ash only affected the coke surface and the entrances of the pores owing to its poor fluidity.After being melted,the catalyzed coal ash was expected to immerge into the inside part of the coke and then react with the coke,resulting in an expansion and increase of coke cavities.The raw coal ash and the unburnt char reduced the coke reactivity,while the catalyzed coal ash improved the coke reactivity.Thereinto,the coal ash containing Fe2O3 exhibited a larger influence on the reactivity than that containing CaO.

试论高炉燃料替代的降碳路径

为有效降低高炉工序的CO_(2)排放量,向高炉喷吹气体、液体或固体燃料来替代焦炭受到广泛的关注。以我国6家典型钢铁企业7座1800m^(3)级高炉2021年的主要技术经济指标为基础,重点分析了燃料比和煤比对高炉CO_(2)排放量的作用和影响。结果表明,6家典型钢铁企业高炉CO_(2)排放量约为1.419~1.595Vt,影响高炉CO_(2)排放量相关性最强的因素且最重要的指标是燃料比,而单纯提高喷煤比的技术手段并不是降低高炉CO_(2)排放量的决定性因素。因此,通过优化喷吹燃料的种类,以氢代碳,实现有效替代,才是降低高炉CO_(2)排放量的有效途径。

新田煤矿选煤厂无烟煤加工优质冶金烧结煤的经济效益分析

阐述了烧结用煤灰分增加对钢铁企业生产的影响,并对新田煤矿选煤厂利用现有选煤工艺,多出优质烧结用煤的经济效益进行了分析,提出多出烧结煤有利于无烟煤资源的更合理利用,同时可提高企业的经济效益。

高炉富氧大喷煤操作实践与性能优化研究

研究了高炉富氧大喷煤操作工艺,探讨了不同富氧率下的关键参数变化以及它们对高炉性能的影响。研究表明:富氧率的调整与控制策略对高炉操作具有重要意义。随着富氧率的增加,煤粉喷射效率提高,炉膛温度分布变宽,CO和H_(2)气体浓度上升,炉渣中SiO_(2)含量下降而Al_(2)O_(3)略微上升,这些变化影响了还原反应效率、热流动性和炉渣特性,为高炉操作提供了改进和优化的方向。

高炉喷吹混加褐煤煤粉的技术研究及应用

保持2500 m^(3)炼铁高炉喷吹时无烟煤含量不变,分别用5%、10%、15%、20%、25%不同配比褐煤替代烟煤制取混合煤样,对其理化、爆炸、可磨、燃烧等性能及着火点温度进行工业化试验研究,结果表明:随着褐煤喷吹量增加,煤比基准期有所降低,焦比、燃料比逐渐增加,褐煤混喷比例稳定在10%~15%,褐煤制粉喷吹系统运行正常。高炉喷吹褐煤后高炉风口煤粉利用率增加,燃料消耗逐渐降低,可降低成本352.20万元。

欧冶炉喷吹煤粉用污泥替代兰炭技术实践

欧冶炉污泥为欧冶炉炼铁过程中产生的固废副产品,其中碳、铁元素含量高,同时含有较高的炼铁有害元素,如锌等。通常需经过脱碳、脱锌等多道工序加工,才能够成为烧结原料,被再次循环利用。八钢欧冶炉工艺技术人员开拓思路,进行工艺创新,将欧冶炉工艺应用在欧冶炉喷吹煤粉中,可充分利用污泥中30%含碳量,以此替代煤粉中的兰炭配比,实现利用欧冶炉系统循环处理工艺来处理厂内堆存的污泥。通过在喷吹煤粉中配加污泥,逐步替代兰炭,利用欧冶炉拱顶区域高温特性(1050~1100℃),实现污泥中碳的再循环利用。通过此项技术攻关,可实现降低欧冶炉燃料比、减少碳排放的目的。

神东矿区商品煤喷吹性能适用性分析

双碳战略驱动动力煤企业积极探索煤炭利用转型发展。高炉喷吹是神东商品煤潜在的有效利用途径。采取神东矿区生产的8种商品煤样品,按高炉喷吹煤要求的基本性质、爆炸性、粉体特性、反应性指标对煤样进行系统测试分析,获得了神东矿区商品煤在高炉喷吹用煤方向的适用性。结果表明,神东商品精煤具有低灰、低硫、中-高挥发分、高发热量的特点。高炉喷吹煤编号为PC-MHVYM-A1-S1属于质量优良的商品煤和良好的喷吹用煤原料。流动性和喷流性指数良好,但爆炸性强,阻碍了神东商品煤在高炉喷吹方向使用。下一步应积极推进工业应用研究,为动力煤低碳使用提供技术支撑。

莱钢型钢1880m^(3)高炉粒煤喷吹改粉煤喷吹的攻关措施

莱钢银山型钢两座1 880 m^(3)高炉原设计采用粒煤喷吹技术,近年来已不能适应生产要求,存在经济性差、制煤量少、燃烧效率低、设备磨损严重等问题。2021年5月改为粉煤喷吹后,从上下部调剂入手,进行提升煤比的攻关,通过采取控制炉腹煤气量、改善煤气流分布及保证煤粉充分燃烧等措施,将煤比由155 kg/t左右提升到170kg/t左右,并阶段性地突破了175 kg/t,同时焦比降低了约15kg/t。高炉不仅实现了由粒煤喷吹改为粉煤喷吹的平稳过渡,而且炉况稳定顺行,平均利用系数达到3.4t/(m^(3)·d),取得了良好的经济效益和社会效益。

高炉喷煤系统配加焦化除尘粉工艺设计

对高炉喷煤系统配加焦化除尘粉工艺设计要点进行了阐述。在总结分析宝钢、太钢焦化除尘粉利用工艺的基础上,提出了焦化除尘粉气力输送进磨煤机新技术,其设计要点一是除尘粉气力输送系统布置方式,二是磨煤机加人点的选取,与宝钢、太钢的工艺相比,该工艺在喷吹煤粉配比精度的控制方面具有明显优势。该工艺在某钢厂高炉应用2年多,喷吹煤粉的配比为50%烟煤+42%无烟煤+8%焦化除尘粉,高炉及喷煤系统没有出现不良反应,煤比保持在高位运行,重力除尘灰检测未发现明显变化。

3200m^(3)高炉喷吹煤粉系统的智能化改造及应用

高炉喷吹煤粉系统是炼铁生产工艺流程的重要环节,高炉对喷煤生产过程的连续性、稳定性要求很高,这就要求喷吹煤粉系统具有较高的自动化控制水平。北营炼铁总厂两座大高炉喷吹煤粉系统经过改造,进一步提高了自动化控制水平,达到了均喷、匀喷、速率稳定、降低氮气消耗的目的。

高炉喷煤速率稳定性的控制与改进

酒钢本部1800 m^(3)高炉的喷吹系统在高罐压大煤量的喷吹过程中出现喷吹罐底部流化板压板断裂、流化板鼓包,清理煤粉筛时杂物堵塞喷煤支管等问题,对喷煤速率的稳定影响较大。针对以上问题,通过对煤粉筛、喷吹罐底部流化板压板进行改造,喷吹运行参数进行调整优化的措施,为稳定喷吹创造了条件,使小时实际喷煤量与计划量的误差稳定控制在±300 kg范围内,降低了瞬时喷吹速率的波动幅度,为高炉稳定炉况优化指标创造了有利条件。