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.

Reduction behavior and kinetics of vanadium–titanium sinters under high potential oxygen enriched pulverized coal injection

In this work, the reduction behavior of vanadium–titanium sinters was studied under five different sets of conditions of pulverized coal injection with oxygen enrichment. The modified random pore model was established to analyze the reduction kinetics. The results show that the reduction rate of sinters was accelerated by an increase of CO and H2contents. Meanwhile, with the increase in CO and H2contents, the increasing range of the medium reduction index (MRE) of sinters decreased. The increasing oxygen enrichment ratio played a diminishing role in improving the reduction behavior of the sinters. The reducing process kinetic parameters were solved using the modified random role model. The results indicated that, with increasing oxygen enrichment, the contents of CO and H2in the reducing gas increased. The reduction activation energy of the sinters decreased to between 20.4 and 23.2 kJ/mol. © 2017, The Author(s).

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.

Practice of the application of lean coal to coal injection in large-scale blast furnaces

This study mainly introduces the technical properties of a kind of lean coal mined from Lu＇ an, a prefecture of Shanxi Province and its application to coal injection in large-scale blast furnaces（BFs） in Baosteel. China is rich in lean coal resources. The technical properties of lean coal, including ash content, sulfur content and caloricity, etc., are similar to those of anthracite coal used in Baosteel, except the fact that the volatile of lean coal is higher. Besides, the explosive property and the coking property of lean coal are suitable for the BF coal injection. In this study, lean coal was tested in the pulverized coal injection （PCI） of a BF. In the test, the blending proportion of lean coal in the coal blend was increased gradually, and the consequential production indexes were traced. All the operational indexes show that the results of the BF coal injection are good, demonstrating that lean coal can be substituted for anthracite coal in the PCI in BFs. With an abundant amount and specific utilization,lean coal is found to be of a high economic value.

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。

高炉喷吹固体燃料物化结构与燃烧性能关系研究

高炉喷吹煤粉技术是现代钢铁企业降本增效的主要技术措施,喷吹固体燃料的燃烧性能是提升煤焦置换比的关键。为明确影响高炉喷吹固体燃料燃烧性能的关键因素,系统分析了不同固体燃料的物化结构与其燃烧性能的关系。结果表明,高炉喷吹固体燃料中碳结构的有序化程度对其燃烧性能有显著的影响,有序化程度越高的样品,在燃烧反应过程中需要更高的能量破坏芳香环的结构,造成其着火温度升高,燃烧速率降低。高炉喷吹煤粉技术在喷吹燃料选择和使用过程中,选取固定碳含量高、发热值高、孔隙结构发达、富含有机官能团和碳结构有序化程度较低的固体燃料进行高炉喷吹,可以有效改善混合煤粉在风口前的燃烧状态,提升高炉喷吹煤粉在炉内的利用率。

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.

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.

德钢4号高炉烟气自循环制粉系统设计

对四川德胜集团钒钛有限公司应用不带脱水装置的烟气自循环制粉工艺进行了介绍和总结,该制粉工艺的烟气炉采用全烧高炉煤气、中速磨煤机制粉、一级大布袋收粉,磨制的烟煤挥发分为25%,在稳定生产期间系统末端氧含量控制在12%以内,粉尘排放浓度<10 mg/Nm^(3)。生产实践表明:不带脱水装置全烧高炉煤气的烟气自循环制粉工艺安全可靠,满足生产要求。

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.

容弹内片状无烟煤粉喷射掺混特性实验研究

粉末在容弹以及发动机燃烧室内的掺混状态对粉末爆轰特性有较大的影响,因此亟须对粉末在有限空间内的喷射掺混特性展开研究。搭建了一套透明的容弹系统,通过高速摄影监测系统,对片状煤粉在容弹内的喷射掺混过程进行观测,并对高速摄影拍摄图片进行后处理,分析煤粉在容弹内的喷射掺混变化规律。针对煤粉喷射掺混图像建立了一种灰度值标准差曲率分析方法,研究发现标准差曲率趋于0的初始时刻为煤粉掺混均匀最佳时刻,可以选取为最佳点火时间点,且该方法所选取的时刻与逐帧分析高速摄影图像所选取的时刻吻合。在煤粉浓度为120 g/m^(3),210 g/m^(3),300 g/m^(3)下,依次展开煤粉喷射掺混实验,并应用此灰度图像标准差曲率分析方法进行分析。实验结果表明:保持煤粉浓度一致时,掺混均匀性最佳时间随喷粉时长的增长而逐渐缩短,点火时刻提前;保持喷粉时长一致时,掺混均匀性最佳时间随供粉浓度的增长而延长,点火时刻延后。

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。

高炉煤粉喷吹控制系统优化方案探讨

对国内冶金行业高炉煤粉的喷吹系统优化技术进行了探讨,对高炉喷吹系统的工作原理、工艺流程、控制设备、仪表、监控参数以及保护措施进行了说明,对喷煤系统的问题点进行了陈述,指出了喷吹控制系统存在的问题,对控制系统进行了优化设计,阐述了喷吹过程中煤粉波动的原因。结合某钢厂喷吹系统的实际问题,提出了一种优化改造方案,采用该方案改造后可有效提升喷吹罐的装粉效率、减少煤粉喷吹速率误差、提高煤粉喷吹精准度。

炼铁喷煤进行高配比烟煤生产实践

在高炉喷吹无烟煤资源采购市场日趋紧张的环境下,榆钢炼铁喷煤系统对原煤配比结构进行优化调整,将烟煤配比由30%调整至38%,煤粉挥发分由14%调整至18%,为了保证制粉系统和喷吹系统的安全生产,喷煤系统对制粉运行设备进行了漏风治理,对各系统关键性工艺控制参数进行了调整,同时严抓原煤配比准确率,稳定烟煤配比,进行了高炉喷煤高配比烟煤的生产实践。

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。

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.

制粉系统烟气自循环工艺应用实践

对河北某钢厂应用不带脱水装置的烟气自循环制粉工艺进行了介绍和总结,该工艺的烟气炉采用全烧高炉煤气、磨煤机磨制的烟煤挥发分为25%,在稳定生产期间系统氧含量控制在12%以内。生产实践表明:全烧高炉煤气的烟气自循环制粉工艺安全可靠,满足生产要求,具有一定的技术优势,值得大力推广。

大比例掺氨下煤粉火焰区喷氨位置对燃烧及NO生成特性的影响

掺烧零碳燃料氨是一种现实可行的燃煤发电减碳技术手段。以某40 MW煤粉燃烧试验炉为研究对象,基于数值模拟研究了煤粉大比例掺烧氨且不采用深度空气分级条件下,纯氨或氨/空气混合气从煤粉火焰区不同位置(根部火焰区、中部火焰区及尾部火焰区)送入炉内时燃烧及NO生成特性。结果表明,无论是纯氨还是氨/空气混合气送入炉内,均使飞灰含碳量略有增加;由于主燃区氧量相对充足,混氨燃烧NO生成显著且出口NO浓度高于单煤燃烧。在纯氨送入方式下,随喷氨位置由煤粉火焰根部区逐渐下移至煤粉火焰尾部区,飞灰含碳量和出口NO浓度逐渐降低。然而,在氨/空气混合气送入方式下,随喷氨位置由煤粉火焰根部区移动至煤粉火焰尾部区,飞灰含碳量和NO浓度逐渐增加。综合考虑燃尽及NO排放特性,纯氨送入时建议由煤粉火焰尾部区送入炉内,而氨/空气混合气送入时建议由煤粉火焰根部区送入炉内,既可有效减弱掺氨对煤粉燃尽特性的影响,又可控制NO生成。