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.

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.

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.

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.

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.

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 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.

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.

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.

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.

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。

生物质重整煤气喷吹-氧气高炉的低碳潜力分析

我国钢铁行业以高炉-转炉长流程为主,一次能源消耗主要为煤粉与焦炭,化石能源消耗大、碳排放高,其中70%的CO_(2)排放集中在高炉炼铁工序。双碳背景下,亟需研发低碳炼铁技术以降低高炉工艺的能源消耗和CO_(2)排放。提出一种生物质重整煤气喷吹-氧气高炉(BRGI-OBF)工艺流程,该工艺通过优化气化炉工艺参数与生物质替代煤粉重整,产生的重整煤气满足高炉的富氢冶炼需求,并降低了化石能源的使用。结合高炉煤气富氧燃烧碳捕集,可实现末流烟气中CO_(2)富集,从而实现高炉低能耗与低碳(负碳)排放。为分析BRGI-OBF工艺的低碳潜力,首先运用Aspen Plus搭建了BRGI-OBF工艺模型,研究了气化炉输入热量与生物质种类对工艺性能的影响。基于计算得到的工艺参数,运用高炉炼铁工艺能耗计算方法,对比分析了传统高炉工艺与炉顶煤气循环-氧气高炉(TGR-OBF)工艺的能耗与碳流情况。结果表明,向气化炉提供适宜的热量可有效减少煤粉用量,同时增加循环煤气量,最多可减少煤粉用量124.2 kg/t(以生铁计);生物质种类对生物质用量与重整煤气的组分产生显著影响,采用杨木半焦进行重整时,杨木半焦用量为204 kg/t,重整煤气中H_(2)体积分数达29.91%,满足富氢冶炼需求。此外,BRGI-OBF工艺显著改善了能源结构,其化石能源占比约55%,与传统高炉相比,降低煤粉消耗17.6%、焦炭消耗29.3%。该工艺流程耦合富氧燃烧碳捕集技术后,末流中存在碳素372.6 kg/t,以易于压缩捕集的高浓度CO_(2)(>90%)形式存在。扣除由杨木半焦造成的碳素排放,总碳素排放为-109.9 kg/t,相当于生产每吨铁水可额外捕集CO_(2)403 kg,可实现生物质+CCS的负碳技术,为钢铁行业实现深度脱碳提供重要支持。

首钢股份高炉喷吹生物质微粉的可行性分析

对首钢股份高炉喷吹生物质微粉的可行性进行了分析。结果表明:①河北省唐山市一年的生物质微粉产量折合约137.64万t,可满足高炉喷吹的燃料需求,生物质资源的使用成本约为877.4元/t,用于高炉喷吹具有较好的经济效益;②几种利用变压闪蒸技术制备的生物质微粉样品中,样品7最适合进行高炉喷吹,其灰分低、水分低,能量密度接近褐煤水平,但后续仍需对工艺参数进行不断优化,以提高品质;③基于1号高炉的生产参数及原燃料质量,用31.6kg/t的样品7替代10kg/t煤粉较为可行,风口热状态相较于基准工况变化较小。

城市碳氢固废粒化预处理产物的高炉喷吹特性

为缓解城市生活垃圾带来的环境污染问题,本文以废弃的食品袋、手提袋、垃圾袋、快递袋、纸屑、秸秆和土壤为原料,按照相应比例进行混合配制,将所得的城市碳氢固废进行粒化预处理并用于高炉喷吹,研究粒化产物的成分、着火点、爆炸性、燃烧性、气化性等高炉喷吹特性。结果表明:城市碳氢固废粒化产物的挥发分、固定碳、灰分质量分数分别为61.56%、19.02%、19.42%,且其热值较高,为25 497.3 kJ/kg;粒化产物的着火点为241℃,与无烟煤混合后着火点升高;粒化产物有强爆炸性,与无烟煤混合后爆炸性减弱。该粒化产物和无烟煤混合后,其燃烧性能和反应性能显著改善。该粒化产物的添加比为40%时,既能保证高炉的安全喷吹,又能对无烟煤的燃烧起促进作用,且生产1 t生铁最多可降低190.4 kg碳排放。研究结果表明,城市碳氢固废可以作为高炉喷吹的优质燃料,同时可在一定程度上降低高炉工序的碳排放。

喷吹神东高钙烟煤对高炉回旋区热状态的影响

高炉风口和回旋区的热状态对炉内煤气流的一次分布具有重要影响,进而影响高炉的经济技术指标。为探究喷吹神东高钙烟煤对高炉回旋区热状态的影响,本文通过收集某钢铁企业试烧期间高炉鼓风参数及其他各项操作参数,采用Fluent仿真模拟方法,建立风口回旋区的三维燃烧模型,系统分析不同喷吹条件下温度分布、气体分布、速度分布的变化规律,从而确定在风口复杂条件下喷吹神东高钙烟煤对高炉回旋区热状态的影响。模拟计算结果表明:神东高钙烟煤和ES无烟煤燃烧后产生的还原气体量最多,生产时有利于矿石的还原;向高炉喷吹神东高钙烟煤、HX烟煤、WN烟煤、SG烟煤与ES无烟煤混合煤粉时,燃尽率分别为72.25%、70.11%、68.87%、67.56%,神东高钙烟煤与ES无烟煤混合喷吹时煤粉的燃尽率最高,这是由于神东高钙烟煤和ES无烟煤的CaO质量分数较高,其在风口、回旋区内的燃烧特性最佳;混合喷吹神东高钙烟煤与ES无烟煤时,风口、回旋区内的煤气成分和煤粉燃尽率等方面要强于其他三种情况,适宜向高炉喷吹。

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。