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).

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.

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。

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.

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.

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.

高炉富氧鼓风技术发展现状简析

高炉富氧鼓风技术取得了明显进展,如新型氧煤枪、SIP等先进高比例富氧技术的推广应用,而面临的难题主要是,高比例富氧后,高炉呈现“上冷下热”和边沿气流发展等状况,影响高炉稳定顺行。2020年,新疆八钢开启氧气高炉冶炼实践,第一阶段实现35%高富氧冶炼目标,第二阶段试验将引入欧冶炉CO_(2)脱除后的煤气,打通煤气循环的工艺流程,实现50%的超高富氧技术突破。展望未来,高炉发展方向是富氧率、喷煤量不断提高,并逐渐步人高富氧大喷煤的背景中,最终走向全氧高炉冶炼。

高富氧喷吹条件下钒钛炉料的软熔性能

高炉炼铁工艺是钢铁冶金中能源消耗量最高的流程之一。在国家“降碳减碳”政策的号召下,保证高炉稳定顺行是节能减排的重要前提。高炉软熔带的位置、形状对炉内煤气流的分布状态及高炉的稳定顺行具有重要影响。本文通过模拟高富氧喷吹条件下高炉的还原性气氛,在不同还原性气氛条件下采用高温熔滴炉进行钒钛炉料的软化熔滴试验。结果表明:随着富氧率的提高,煤气中CO的体积分数增加,钒钛炉料的软化开始温度和软化结束温度均降低,软化温度区间变大;当CO体积分数从30%增加到45%时,软化开始温度下降72℃,软化结束温度下降43℃,软化温度区间扩大29℃。富氧喷吹后,熔化开始温度升高,炉渣流动性变好,滴落物质量增加;富氧喷吹后,钒钛炉料的软熔带整体呈现“上移扩大”的趋势,软熔带的最高压差逐渐降低,透气性得到改善,Ti元素向渣中迁移增强,Fe元素向渣中迁移得到抑制。

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。

中天钢铁3号高炉大矿批冶炼的主要措施

对中天钢铁3号高炉大矿批冶炼的主要措施进行了总结。3号高炉开炉后,在建立操作炉型期间,通过采取改善原燃料质量、优化基本操作制度、高富氧大喷煤、稳定炉体热负荷等措施,矿批逐步从90t扩大至111t,炉况稳定顺行,主要技术经济指标明显改善,实现优质、高产、低耗的目标。在人炉品位只有56.5%~57.2%的条件下,取得了燃料比495.88kg/t、煤比163.31kg/t的良好指标,不仅消除了建立操作炉型的“阵痛”,同时还降低了生铁成本。

富氧率提升下的钒钛矿高炉冶炼

对承德钒钛某2500 m3高炉提高富氧率的生产实践进行了总结,系统地分析了富氧率提高对钒钛矿高炉冶炼生产的影响。高炉提富氧后,在相同的w[Si+Ti]条件下,理论燃烧温度有所提高,降低w[Si+Ti]仍能保证铁水有充足的物理热;通过合理配煤,炉况更容易稳定,在铁水温度不变的前提下,更适合于低w[Si+Ti]冶炼。根据研究结果,从高炉工艺操作制度、理论燃烧温度控制、高富氧条件下生产组织优化以及提高富氧对炉缸活跃程度的影响等方面入手,研究了钒钛矿冶炼高炉长期保持高富氧率的工艺操作方法。通过对装料制度、送风制度以及喷煤工艺的优化调整以及加强炉前管理等一系列措施,实现了钒钛矿高炉冶炼在高富氧条件下的长周期稳定生产,钒回收率与以往相比显著提高。

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。

高炉炼铁工艺中大喷煤量与富氧率的协同优化研究

研究了高炉喷煤量与富氧率的合理搭配对高炉性能的影响。通过前期实验设置,对不同操作条件下的参数和性能进行了深入分析。在实施合理搭配时,精确控制了喷煤系统和氧气供应系统,持续监测了高炉的温度分布、燃烧效率、还原反应速率、CO和CO_(2)排放以及铁的产量等关键参数。对比结果显示,适度的喷煤量和富氧率,表现出最佳性能。在该条件下高炉内的温度分布更均匀,燃烧效率更高,还原反应速率更快,CO和CO_(2)排放减少,铁的产量显著提高。

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。

高炉喷煤系统倒料工艺优化与创新

对莱钢型钢炼铁厂2×1880 m 3高炉配套喷煤系统进行介绍,针对原倒料工艺系统存在的问题,利用高炉大修期间对喷煤系统倒料工艺进行了优化和创新,采取了更换磨损管道并加粗主管道、增加切断阀门、加设预留口等措施,保障了煤粉的流动性,实现6组喷吹罐均可向粒煤一期和粒煤二期收粉系统进行倒料,为拆卸更换旋转喂料机检修创造条件。