小块焦对高炉焦比的影响

在高炉冶炼过程中小块焦一直被认为只是作为资源再利用,使用时常常不被看好。通过实验室的探索性研究,了解到小块焦的粒度效应对其失重率作用很大,小块焦的反应性相对于冶金焦有很大的提高。可以认为小块焦在炉内改善了还原性,有促进矿石还原作用。小块焦的大量气化吸热有降低热储备区温度的倾向,对高炉的燃料消耗进一步降低起了一定作用。750 m3高炉的生产性试验结果表明,提高小块焦的用量有利于燃料消耗的降低,其他工艺参数不变,增加1 kg/t的小块焦相当于置换焦比1.19 kg/t。     

Determination of thermal histories of coke in blast furnace through X-ray analysis

Abstract

A study has been undertaken to identify the source of coke fines sampled from the deadman area of the blast furnace. Using measurements of the coke crystallite dimension L _C, it was established that some of the fines found in the deadman area of a blast furnace were not simply the degradation products of the lump coke in this area. The L _C was measured using standard X-ray analysis techniques. The coke fines had a higher L _C than the coke lump and therefore have experienced a higher maximum temperature than the associated coke lump. This finding has been interpreted as at least some of the coke fines found in the deadman area (lower temperature region) have been blown there from the raceway by the high velocity hot blast.     

A static approach towards coke collapse modelling in blast furnace

Abstract

Burden distribution control in a blast furnace has a close relationship with wind acceptance and gas utilisation. Quantification of radial distribution of ore and coke is important for proper control of blast furnace operation. Charging of metallic burden over a layer of coke causes a portion of the coke layer to get dislodged from its original position, similar to the situation observed when a heavy material is dropped on a bed of lighter particles. This phenomenon, designated 'coke collapse', significantly changes the ore/coke distribution in the radial direction and thus affects the permeability of the furnace shaft. In the present work a mathematical model for quantifying the amount of coke collapse has been proposed on the basis of 'stability of slope theory'. The calculation from this model has been compared with the results from experiments in simplified physical models. Predictions of the mathematical model are in good agreement with experimental results.     

Programmed heating of coke ovens for increased coke size

Abstract

Large, uniform sized coke is desirable for blast furnace use. It has previously been shown that the coke oven flue temperature in the first few hours of coking is a key determinant of coke size. In this paper, the authors present a new programmed heating approach, which is called pulsed heating, aiming to increase coke mean size at a given average flue temperature. The approach takes into account the charging sequence in coke oven batteries and the authors demonstrate how existing operating practice can be modified in batteries with suitable heating systems to achieve the desired heating programme. A mathematical model of fissure formation provides a prediction of the increase in coke mean size using pulsed heating, compared with standard heating. Pilot scale experiments have also been performed to validate the modelling approach. The results of the modelling indicate that the mean coke size can be increased by several millimetres in some cases, although results from the pilot scale show that pulsed heating increases coke size, but by a smaller amount than that predicted by the model. The potential advantages and limitations of pulsed heating are discussed, as well as opportunities for further investigation of the approach.     

高炉使用铁焦的㶲分析

 中国钢铁生产主要以高能耗和高排放的高炉-转炉长流程为主,节能减排压力较大。因此,积极研发高炉低碳炼铁技术,促进高炉工序CO₂减排尤为重要。铁焦是将含铁原料加入适宜的煤中,经焦化或炭化后成型的新型碳铁复合炉料,其高反应性可以显著降低热储备区温度、降低碳消耗,高炉使用适量的铁焦可实现一定程度的节能降碳。基于现场生产数据,采用㶲分析理论,建立高炉使用铁焦的㶲平衡模型,探索铁焦添加量对高炉物料消耗及能量利用效率的影响。结果表明,高炉使用铁焦后,炉内间接还原得到发展,碳利用率提高,炉内灰分量降低,冶炼单位生铁的碳素消耗和炉渣量均会降低,与未使用铁焦相比,高炉使用114 kg铁焦后,吨铁碳素消耗降低25.95 kg,渣量降低11.28 kg。此外,铁焦内部的金属铁仅需熔化,节省还原所需的㶲量,焦炭和鼓风带入㶲会显著降低,因此高炉冶炼吨铁消耗的总㶲量降低,同时,炉内传热也得到改善,内部㶲损失有效降低,与未使用铁焦相比,高炉使用114 kg/t铁焦后,目的㶲效率由46.14%提高至48.87%,热力学完善度由87.46%提高到88.02%。在此条件下,高炉吨铁的内部㶲损失降低192.63 MJ,实现节能6.57 kg(标煤)。     

利用高含碳金属化团块实现高炉炼铁的节焦

 高炉炼铁是主要的铁水生产工艺,低焦比炼铁一直是高炉节能的重要指标。研究了高含碳金属化团块在高炉中的应用,以达到节约焦炭的目的。利用超细氧化铁粉和非焦煤煤粉为原料在管式加热炉中通过直接还原制备了碳质量分数为15.6%的高含碳金属化团块;在模拟高炉环境的条件下,考察了团块质量变化、团块部分反应后抗碎强度变化和团块微观结构变化;利用自制的热重装置考察了团块内碳的气化动力学;以试验结果为基础,结合高炉数学模型,对利用高含碳金属化团块实现高炉炼铁节约焦炭的效果进行了定量分析。试验结果表明,在高炉环境下,团块部分反应后抗碎强度可以保持在1 200 N/个以上,团块的反应主要为碳溶损反应,且团块有较高的CO₂反应性。对2 500 m3高炉的模拟结果表明,在高炉的含铁炉料层中添加质量分数为5%的高含碳金属化团块,生产率可以提高419 t/d,生产1 t铁水可以节约焦炭11.3 kg,且高炉的操作参数不需要进行调整。     

重新认识高炉用焦炭与CO2的反应性

简要介绍了现行焦炭反应性试验方法的来源,主要表达焦炭在高炉内进入风口回旋区前抗CO2,气化能力以及反应后的抗粉化能力,是一种规范性试验方法。回顾了国内外对焦炭反应性的认识和变化,20世纪认为反应性表达焦炭在高炉抗CO2,的气化能力,反应性高反应后强度低对高炉生产不利。进入21世纪,新日铁提出反应性只是表达了焦炭的活性,认为提高反应性可以提高高炉反应效率,对高炉生产有利,不同时期认识水平不同认知也会完全相反。通过CO2,含量和反应温度对焦炭反应性影响试验和高炉碳平衡计算,分析了喷吹煤粉高炉内焦炭的行为．确定了焦炭进入风口回旋区前的反应失重率。提出现行国家标准“焦炭反应性及反应后强度试验方法”的反应性表达的是焦炭与CO2,反应的活性,高炉内焦炭反应失重率控制因素是矿石的还原性能和未燃煤粉率,与焦炭实验室测定的反应性无关。     

Experimental study on the effect of using nut coke on the permeability of packed beds in blast furnaces

The charging pattern may affect blast furnace permeability,coke ratio,and the freedom to select low-grade raw materials. Ore-coke mixed charging is a potential technique for optimizing the charging pattern. In recent years,charging small-sized coke( nut coke) into the burden layer has been applied to save raw materials and decrease cost.Although mixed charging,especially adding nut coke into the burden layer,may have many advantages,the mechanisms and side effects of nut coke use are not well understood,and the mixing ratio is still limited in industrial blast furnace operation. In this study,the status of mixed charging,especially nut coke used in blast furnaces,was investigated. A cold flow model was established to study the permeability of the packed bed in the blast furnace "dry zone"under different conditions with the aim of better understanding the mechanisms of mixing coke and nut coke into the burden layer. The effect of coke size,mixing coke ratio,layer numbers,and gas flow rate on the pressure drop of the packed bed was investigated. The experimental results show that mixing the nut coke in the ore layers decreases the pressure drop to different extents depending on mixing ratio.     

Influence of coal fluidity on coal blend and coke quality

Abstract

The blast furnace coke quality depends on the characteristics of coal blend, precarbonisation techniques adopted such as stamping, vibrocompaction etc., and coking conditions. Of the above, coal blend plays a significant role in the production of quality coke. Furthermore, the quality of the blend depends on the quality of individual coals and their interaction making up the blend. Coal, being a highly heterogeneous material, requires special care for determination of its properties and blending of individual coals for coke making. Coal fluidity is one such important coking property which highly influences the coke quality. The hard coking coals having good fluidity, which yield good coke, however are not only very expensive, but also are limited in reserves. Unlike, other properties, coal loses its fluidity on weathering, i.e. oxidation in presence of air on long storage in the yard, and the fluidity value changes on blending with different coals. To understand the effect of coal fluidity on coal blending and there by the coke quality, studies have been conducted using the industrial scale coals and coal blends. An empirical relation has been developed between actual blend fluidity and calculated fluidity using logarithmic weighted average from fluidity of individual coals. Blending of non-coking coals above 20% with the hard coking coals used in this research decreases the blend fluidity and impairs the coke quality. It was seen that the coals lose their fluidity on weathering, and the value becomes less than half after a two months of storage at site. Weathering appears to be more rapid in case of semisoft than hard coking coals. The present paper discusses the influence of coal fluidity on coal blend fluidity and changes on weathering.     

焦炭热性能对高炉操作影响的研究进展

通过调研国内外焦炭热性能对高炉操作影响的研究进展,发现日本炼铁界对焦炭反应性关注度较高,且观点较一致:在确保焦炭冷、热态强度的前提下,较高反应性的焦炭有利于抑制风口部位焦炭的粉化和改善高炉炉内矿石还原速度,利于低成本冶炼;国内对焦炭反应性对高炉操作影响机理方面的探讨较日本少,观点与日本不同,认为焦炭具有较低的反应性和高强度利于高炉操作。建议更为全面深入研究热性能对高炉操作的影响,并在生产实践中进行探索,以求在领域内达成共识。     

高炉内兰炭与焦炭之间的交互作用

通过热重分析实验和模拟氧气高炉中炉料反应行为,探究兰炭和焦炭的反应性,以及兰炭和焦炭之间的交互作用.热重实验结果表明,兰炭反应性优于焦炭,兰炭在加热过程中出现2个DTG峰值,第1个峰值是由于兰炭的二次热解,第2个是由于热解和气化耦合反应.在加热到800 ℃之后,兰炭和焦炭之间存在交互作用,并且随着升温速率的增加,交互作用增强.在高炉炉况下,兰炭的加入能够减少焦炭的反应和焦炭粉化程度,降低CO₂和H₂O气体对焦炭气孔壁的侵蚀作用,降低大孔的生成,从而对焦炭起到保护作用.      

Effect of mixing charge of highly reactive semicoke nut on the reaction of high Al2O3 ferrous burden in blast furnace

In order to improve the performance of blast furnace ironmaking when using the high Al₂O₃ iron ore, the technology of mixing charge of high reactive semicoke nut with ferrous burden was proposed and systematically investigated at laboratory scale in the present paper. The CO₂ gasification activation energy of semicoke ranged from 136.5 to 150.3?kJ?mol^?1, which was lower than that of the traditional coke. At the temperature of 1200°C, the reduction degree of ferrous burden increased a little with the addition of semicoke nut and the consumption ratio of semicoke was 14.0?wt-% under the simulated blast furnace ironmaking condition. The mixing charge of semicoke could obviously reduce the softening beginning temperature, increase the melting temperature and improve the permeability compared with the standard and traditional coke mixing charge samples. During the total softening and melting process, about 90?wt-% of the semicoke nut and 45?wt-% of the traditional coke nut were consumed, respectively. The experiment results indicated that the mixing charge of high reactive semicoke nut could obviously improve the performance of blast furnace ironmaking when using high Al₂O₃ ferrous burden and the semicoke was more effective than traditional coke.     

高炉入炉焦/风口焦微观结构与气化反应性对比

摘要：以同一座高炉2次休风所取的入炉焦和风口焦为研究对象,采用XRD、SEM EDS、N2吸附、热分析等方法比较分析不同样品的碳化学结构、碱金属富集程度、孔隙结构、CO2气化反应性,探究了焦炭在高炉中反应性变化程度和影响因素。结果表明：风口焦炭与入炉焦炭相比,气化反应性显著升高,比表面积增大,碳结构有序化程度升高,碱金属含量提高;金属钾在风口焦炭边部的存在形式以可溶性盐为主,在焦炭内部以钾霞石为主;入炉焦各部位差异较小,而风口焦边部、中部、芯部的气化反应性和结构性质存在显著差异,表明其各部位在高炉中所经历的气化反应过程不同;风口焦中碱金属含量为影响气化反应性的最主要因素,次要影响因素为碳化学结构和孔隙结构。     

Numerical simulation on novel blast furnace operation of combining coke oven gas injection with hot burden charging

A novel blast furnace operation of coke oven gas (COG) injection simultaneously with hot burden charging has been proposed to solve the problem of insufficient heat in the BF shaft zone under the condition of COG injection and make full use of the abundant sensible heat of high temperature burden. In this paper, the novel process has been simulated with a multifluid blast furnace model. The results show that, in comparison with the operation of COG injection only, under the operation of COG injection together with hot burden charging, the temperature in the upper zone of the shaft increases while that in lower zone decreases. Furthermore, the reduction of iron bearing material is improved in the top zone, and the cohesive zone tends to descend and narrow. The coke ratio, fuel ratio and CO₂ emissions of the operation of charging hot pellet and coke with the temperature of 800°C are decreased by 4.0, 4.7 and 5.3% respectively, while the hot metal productivity is increased by 7.14%. Therefore, COG injection combined with hot burden charging operation not only increases temperature in the upper part of the blast furnace but also decreases energy consumption per tonne hot metal.     

Blast-furnace operation with coke fines

Conclusion Depending on the smelting conditions, the use of coke fines (36-25 mm) for up to 22% of the coke charged into a blast furnace having a standard bell-and-hopper charging appratus, led to a decrease in pig-iron output by 1.0–1.6% (or 0.2–0.4% for each 1% of coke fines), an increase in unit coke consumption by 0.8–1.0% (or by 1.0%-0.19-0.17%), and a deterioration in the drainage capacity of the hearth. The performance indices of the furnace equipped with a revolving distributor show that it is possible to force smelting while using up to 25% coke of the 36-25-mm fraction in the charge. If the coke in the charge consists of more than 30% fines, smelting rate decreases and hearth performance declines. These developments are accompanied by a 3.3–3.6% reduction in furnace productivity (0.12–0.13% for each 1.0% of the 36-25-mm fraction of coke) and a 0.85–0.90% increase in unit coke consumption (0.03–0.04% for each 1% of coke fines). West Siberian Metallurgical Combine. Translated from Metallurg, No. 1, pp. 38–39, January, 1999.     

基于里斯特操作线解析有害元素对高炉焦比的影响

分析了有害元素在高炉内的循环行为,结合高炉实际生产参数,运用里斯特操作线进行计算,揭示了有害元素对焦比的影响规律,建立了焦比与有害元素入炉负荷和循环富集倍数之间的定量关系.计算结果表明:有害元素在高炉内"还原-氧化-再还原"的循环过程会将高温区的CO转移到低温区,降低煤气利用率,同时消耗了高温区大量热量,从而使焦比升高.不同有害元素的影响程度不同.有害元素循环富集倍数对焦比影响的强弱顺序为:Na > K > Zn,有害元素入炉负荷对焦比影响的强弱顺序为:Zn > Na > K.进一步的分析表明,Na、Zn对高炉焦比的影响大于K.但考虑到K对焦炭劣化的作用更明显,故要严格控制K、Na、Zn的入炉负荷.基于上述计算得到的定量关系,利用高炉不同有害元素入炉负荷以及焦比进行曲线拟合,预测高炉有害元素的循环富集倍数.曲线拟合结果与高炉解剖实验结果相吻合.      

高炉大型化后对焦炭性质及在炉内劣化的思考

 焦炭作为高炉炼铁的主要燃料,对高炉的顺行和高效冶炼发挥着极其重要的作用,随着高炉大型化和智能化的发展,对焦炭质量及对其的评价、预测和控制的要求亦越来越高。针对高炉内不同部位焦炭的劣化经历、劣化后焦炭的高温反应特性及焦炭组织结构的变化进行了分析。依据国内一些特大型高炉的生产实践,提出了在达到高水平高炉操作指标时不同容积高炉焦炭高温反应特性所需的指标,并对适合评价高炉大型化焦炭劣化后质量的标准做了探讨。     

兰炭替代部分焦炭对焦炭层透液性的影响

为探究高反应性兰炭替代部分焦炭加入高炉的可行性,文章通过对气化后的焦炭和兰炭进行冷、热态透液性试验,获得液体在焦床中的流动速度、滴落量及滞留量.结果表明,在高炉上部气化阶段,高反应性兰炭对焦炭有一定的保护作用.在冷态滴落实验中,小粒径燃料条件下,随着兰炭比例的增加,液体滴落速度变缓,滴落量降低16.8％.当兰炭粒度增加...     

攀钢高炉焦丁混装入炉生产实践

介绍了攀钢高炉开展矿石、焦丁混装入炉的研究和生产情况 ,焦丁回收混装入炉设施充分利用了本厂现有设备 ,工程投资少见效快。用焦丁代替冶金焦与矿石混装入炉不但节省焦炭降低生产成本 ,而且有利于钒钛矿冶炼 ,使高炉稳定高产。     

焦炭喷洒ZBS改质剂的改性机理及生产实践

针对阳春新钢铁炼铁高炉所采购焦炭品种多、质量波动大,造成高炉炉况波动、成本偏高的问题,进行了焦炭提质增效的工业性试验研究.通过向焦炭立体喷洒ZBS焦炭改质剂,研究了ZBS改质剂与焦炭的相互作用行为,阐述了ZBS改性机理.研究发现,经过ZBS改性后的焦炭形成了碳的络合物和化合物,改变了碳的结构,提高了焦炭的石墨化度.经Z...