Cross-upgrading of biomass hydrothermal carbonization and pyrolysis for high quality blast furnace injection fuel production:Physicochemical characteristics and gasification kinetics analysis

The paper proposes a biomass cross-upgrading process that combines hydrothermal carbonization and pyrolysis to produce high-quality blast furnace injection fuel.The results showed that after upgrading,the volatile content of biochar ranged from 16.19%to 45.35%,and the alkali metal content,ash content,and specific surface area were significantly reduced.The optimal route for biochar pro-duction is hydrothermal carbonization-pyrolysis(P-HC),resulting in biochar with a higher calorific value,C=C structure,and increased graphitization degree.The apparent activation energy(E)of the sample ranges from 199.1 to 324.8 kJ/mol,with P-HC having an E of 277.8 kJ/mol,lower than that of raw biomass,primary biochar,and anthracite.This makes P-HC more suitable for blast furnace injection fuel.Additionally,the paper proposes a path for P-HC injection in blast furnaces and calculates potential environmental benefits.P-HC of-fers the highest potential for carbon emission reduction,capable of reducing emissions by 96.04 kg/t when replacing 40wt%coal injec-tion.

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.

Micromorphology and safety properties of meager and meager-lean coal for blast furnace injection

Four types of meager and meager-lean coal and one type of high-quality anthracite were selected based on the safety requirements for blast furnace coal injection and domestic coal quality to conduct microstructure and component analyses.The analyses of the organic and inorganic macerals and the chemical compositions of the selected coal samples indicate that the four types of meager and meager-lean coal have low volatilization,low ash content,and low sulfur content;these qualities are suitable for blast furnace injection.Grindability test was conducted on the four types of meager and meager-lean coal and the anthracite mixed coal samples.Results indicate that the mixture of meager and meager-lean coal and anthracite is beneficial to improve the grindability of pulverized coal.The explosive tests reveal that the selected coal samples are non-explosive or weakly explosive.When the proportion of meager and meager-lean coal is less than 40wt%,the mixed coal powder would not explode during the blowing process.The minimum ignition temperature test determines that the minimum ignition temperatures of the four types of meager and meager-lean coal and anthracite are 326,313,310,315,and 393°C,respectively.This study provides a guiding research idea for the safety of meager and meager-lean coal used in blast furnace injection.

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.

Modeling of the effect of hydrogen injection on blast furnace operation and carbon dioxide emissions

The effect of hydrogen injection on blast furnace operation and carbon dioxide emissions was simulated using a 1D steady-state zonal model.The maximum hydrogen injection rate was evaluated on the basis of the simulation of the vertical temperature pattern in the blast furnace with a focus on the thermal reserve zone.The effects of blast temperature and oxygen enrichment were also examined to estimate coke replacement ratio,productivity,hydrogen utilization efficiency,and carbon dioxide emission reduction.For blast temperature of 1200℃,the maximum hydrogen injection rate was 19.0 and 28.3 kg of H_(2)/t of hot metal(HM)for oxygen enrichment of 2vol%and 12vol%,respectively.Results showed a coke replacement ratio of 3-4 kg of coke/kg of H_(2),direct CO_(2) emission reduction of 10.2%-17.8%,and increased productivity by up to 13.7%depending on oxygen enrichment level.Increasing blast temperature further reduced the direct CO_(2) emissions.Hydrogen utilization degree reached the maximum of 0.52-0.54 H_(2)O/(H_(2)O+H_(2)).The decarbonization potential of hydrogen injection was estimated in the range from 9.4 t of CO_(2)/t of H_(2) to 9.7 t of CO_(2)/t of H_(2).For economic feasibility,hydrogen injection requires revolutionary progress in terms of low-cost H_(2) generation unless the technological change is motivated by the carbon emission cost.Hydrogen injection may unfavorably affect the radial temperature pattern of the raceway,which could be addressed by adopting appropriate injection techniques.

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.

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.

Non-water Injection Mix for Blast Furnace YB/T 4153-2006

1 Scope This standard specifies the classification, techni cal requirements, test methods, quality appraisal pro- cedures, packing, marking, transportation, storage, quality certificate, and construction manual of nonwater injection mix for 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.

Numerical simulation of the effect of coaxial and cross-axis injection modes on pulverized coal combustion in the raceway of blast furnace tuyere

The aim of this study is to investigate the influence of the angle of the pulverized coal (PC) injection lance on the combustion characteristics of fuel in the raceway of blast furnace tuyeres. Using FLUENT software, a Euler-Lagrange three-dimensional numerical model was constructed to analyze the influence of different positions of blast furnace tuyere coal powder injection lance (coaxial and cross-axis) on key parameters such as temperature distribution, gas flow, and combustion efficiency. The results demonstrate that adjusting the angle of the injection lance significantly modifies the average and peak temperatures in the raceway, while the composition of gas components remains relatively stable. When the injection lance angle is 10°, the average temperature and peak temperature in the raceway are 2294 K and 2747 K, respectively. When the injection lance angle is 12°, the combustion efficiency of the PC reaches 80.8%. This study reveals the significant impact of the injection lance angle on the combustion process. Especially at an angle of 12°, the combustion efficiency of the blast furnace significantly improves. With coaxial injection, the combustion rate increases as the distance between the injection lance tip and the tuyere increases. This paper is instructive for the optimization of the blast furnace combustion system, which improve fuel utilization efficiency and reduce environmental emissions. This paper provides practical recommendations for adjusting blast furnace operational parameters, offering insights for achieving more efficient and environmentally friendly industrial production.

Combustion performance of pulverized coal and corresponding kinetics study after adding the additives of Fe_(2)O_(3) and CaO

Combustion performance of pulverized coal(PC)in blast furnace(BF)process is regarded as a criteria parameter to assess the prop-er injection dosage of PC.In this paper,effects of two kinds of additives,Fe_(2)O_(3) and CaO,on PC combustion were studied using the thermo-gravimetric method.The results demonstrate that both the Fe_(2)O_(3) and CaO can promote combustion performance index of PC including igni-tion index(C_(i)),burnout index(D_(b)),as well as comprehensive combustibility index(S_(n)).The S_(n) increases from 1.37×10^(−6) to 2.16×10^(−6)%2·min^(−2)·℃^(−3) as the Fe_(2)O_(3) proportion increases from 0 to 5.0wt%.Additionally,the combustion kinetics of PC was clarified using the Coats-Redfern method.The results show that the activation energy(E)of PC combustion decreases after adding the above additives.For instance,the E decreases from 56.54 to 35.75 kJ/mol when the Fe_(2)O_(3) proportion increases from 0 to 5.0wt%,which supports the improved combustion per-formance.Moreover,it is uneconomic to utilize pure Fe_(2)O_(3) and CaO in production.Based on economy analysis,we selected the iron-bearing dust(IBD)which contains much Fe_(2)O_(3) and CaO component to investigate,and got the same effects.Therefore,the IBD is a potential option for catalytic PC combustion in BF process.

Hot Blast Flow Measurement in Blast Furnace in Straight Pipe

This article shows an innovative method to model and validate the hot air flow through the blast furnacés tuyeres. This study will be the basis for flow measurements implementation and safety interlocks for the pulverized coal injection. The flow measurements were taken in the blast furnace down leg pipes by installing refractory Venturi tubes. The system for the calculation of differential pressure takes into consideration the dimension of the Venturi, the air density and compressibility. The objective is to specify the flow transmitters required to automate a control system and implement safety interlocks for the coal injection plant.

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.

Evaluation of Four Coals for Blast Furnace Pulverized Coal Injection

One of the effective methods of reducing coke consumption is pulverized coal injection. The most important problems encountered in this method are reduced permeability, unburned and high ash content. To select the best coal for injection, suitable tests can be used. Therefore, experiments such as proximate and ultimate analysis, Rock- Eval and combustion tests were performed on four kinds of coals from different mines, including Sarakhs, Sangrood, Karmozd, and Tabas. The results of proximate and ultimate analysis indicated that although the sulfur content and ash content of selected coals were a little high, they were suitable for coal injection. The results of combustion experiments and Rock-Eval tests showed that Karmozd coal was the best one to be injected into blast furnace. The result indicated that the mixing of coals could improve the combustion properties of pulverized coals.

Influence of hydrogen-enriched atmosphere under coke oven gas injection on reduction swelling behaviors of oxidized pellet

It is of great importance to elucidate reduction swelling behaviors and reaction mechanism of oxidized pellet in hydrogen-enriched atmosphere under coke oven gas injection. In this work, the effects of hydrogen concentration in N_2-CO-H_2 atmosphere with unchanged CO content on reduction swelling behaviors of oxidized pellet at 1173 K were studied, to clarify the mechanism of hydrogen-enriched reduction and exclude the influences of CO. Then, the reduction swelling behaviors of oxidized pellet at 1173 K in actual atmosphere under coke oven gas(COG) injection, got from the simulation results of multi-fluid blast furnace model, were investigated. The results show that with the concentration of hydrogen increasing in N_2-CO-H_2 gas from 2% to 18%, the reduction swelling index of pellet decreases from 10.12% to 5.57% while the reduction ratio of pellet increases obviously from 39.85% to 69.58%. In addition, with COG injection rate increasing from 0 to 152.34 m^3/t, the reduction swelling index of pellet decreases slightly from 10.71% to 9.54% while the reduction ratio of pellet is increased from 31.57% to 36.39%. The microstructures of pellet are transformed from the platy structure to the flocculent structure.

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。

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。

高炉喷吹煤粉预热工艺技术进展及应用

煤粉预热可提高高炉喷吹煤粉的初始温度,加强煤粉在风口前的气化热解过程,降低喷煤对风口区域热风的冷却效应,进而提高煤粉燃烧率,为高煤比创造条件。对现有几种煤粉预热工艺,如高炉废烟气对流预热、电磁感应预热、立式筒仓管板预热和流化床预热技术特点依次进行了分析。高炉废烟气对流预热工艺,充分利用高炉煤气和热风炉废烟气余热,既能提高煤粉初始温度,又能减少能源浪费。攀钢钒高炉和舞钢高炉预热煤粉工业试验结果表明,提高煤比和降低焦比的效果良好,应用前景广阔。