气基竖炉直接还原技术的发展现状与展望

 阐述了气基竖炉直接还原工艺的技术特点和发展现状,分析了在中国资源和能源条件下气基竖炉直接还原技术发展所面临的主要问题。基于气基竖炉直接还原工艺的特点,对该工艺的原料、还原气等进行了分析研究。指出非常规天然气资源的有效开采和加压煤制气工艺投资、运行成本的显著降低,将是未来气基竖炉直接还原技术发展的主要推动力,同时利用钢铁企业过剩的煤气资源和中国局部地区相对丰富的天然气资源生产直接还原铁,是今后中国气基竖炉直接还原技术发展的重要方向。参照唐山地区的原料和能源价格,对年产量为80万t/a的直接还原铁装置的生产成本和技术经济可行性进行了分析,分析结果表明：原燃料价格波动对DRI成本影响显著,其中还原气成本约占DRI生产成本的10%~25%;若按DRI替代转炉废钢计算效益,要求天然气价格低于1.8元/m3。     

气基竖炉直接还原球团技术的发展

论述了球团矿质量对气基竖炉直接还原生产和DRI质量的影响以及DRI质量对炼钢生产的影响.介绍了提高气基竖炉直接还原工艺用球团矿质量的技术,包括降低Si02含量、降低粘结趋势、提高还原性和提高大粒度(12.5～16.0 mm)球团比率等措施及其发展.指出若把低TFe、高脉石含量的高炉用球团矿直接用于气基直接还原竖炉,至少应该采用球团涂层技术;如果球团矿脉石含量较高,需要借助工业试验进行综合分析以确定其经济性.     

Hydrogen-Based Direct Reduction of Iron Oxides Pellets Modeling

The present study deals with the analyses of the direct reduction kinetics during the hydrogen reduction of industrial iron oxide pellets. Various types of pellets with different percentage of total iron content and metal oxides are examined. They are reduced at different temperatures and pressure (700–1100 °C and 1–6 bar) in hydrogen atmosphere. The reduction behavior is described in terms of time to reduction, rate of reduction, and kinetics constant. All the obtained results are analyzed through the employment of a commercial multiobjective optimization tool to precisely define the weight that each single parameter has on the reduction behavior. It is shown that from the point of view of the processing conditions, temperature is the main factor influencing the time to total reduction. From the point of view of the pellets properties, it is mainly influenced by the total iron percentage and then by porosity and basicity index. Also, the kinetics behavior is largely influenced by the reduction temperature even if it is mainly governed by the porosity and pores size from the point of view of the reduced pellets. The reduction rate is also mainly influenced by temperature and then by iron percentage, gas pressure, basicity index, and porosity.     

含钒钛铁精矿氧化球团气基竖炉直接还原模拟试验

我国钒钛磁铁矿资源丰富,但综合利用难度大,现有工艺仍存在一些问题,工艺流程还有待完善和革新。气基竖炉直接还原-电炉熔分新工艺为钒钛磁铁矿资源清洁高效综合利用提供了新途径。以含钒钛的铁精矿为原料制备氧化球团,模拟气基竖炉直接还原条件,研究了还原气组分和温度对球团的还原进程、还原膨胀以及还原强度的影响。结果表明:以钒钛铁精矿为原料,配加1%膨润土,在1 250℃下焙烧20 min后,所制备氧化球团性能良好,具有较高的抗压强度。在恒定还原气组分(纯H2、H2/CO=2.5、H2/CO=1、H2/CO=0.4和纯CO)和温度(850、900、950和1 000℃)下,钒钛铁精矿球团还原速率快、还原膨胀率小(<20%),可满足气基竖炉直接还原工艺要求。煤制气-气基竖炉直接还原凭借其能耗小、环境友好、单机产能大、产品质量好等优点,将在钒钛磁铁矿资源高效清洁综合利用领域得到发展。     

中国发展非高炉炼铁的现状及展望

非高炉炼铁是钢铁工业发展的前沿技术之一。目前,直接还原已成为世界钢铁工业不可缺少的组成部分。熔融还原虽实现工业化生产的环境优越性得以公认,但其低能耗、低成本等优点还有待于实践证实。发展直接还原铁生产弥补废钢的短缺是中国钢铁工业、装备制造业发展的急需。以国内技术为基础,利用国内铁矿资源,以煤制气 竖炉为主导工艺是中国发展直接还原铁生产的主要方向。加强对国外熔融还原技术发展的跟踪,强化国内熔融还原技术的开发力度,尤其是消化COREX技术以及实现其装备的国产化是中国熔融还原发展的重要方向。     

煤制气生产直接还原铁的联合工艺方案

 在分析比较了几种主要煤制气和直接还原工艺的基础上,结合中国的资源特点,提出了180万t/a规模壳牌煤气化与HYL/Energiron竖炉生产直接还原铁的联合工艺流程,并对联合工艺的主要参数进行了计算。结果表明：联合流程在能耗及环保指标上与传统高炉相比具有一定先进性。并对国内不同地区和原料条件下的生产技术经济指标进行了对比,为煤制气生产直接还原铁的工程化提供方案参考。     

Study on the Shaft-Direct Reduction Process with Cold Bound Pellet

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Influence of Wall Angle of Direct Reduction Shaft Furnace on Particle Flow Pattern by DEM Modeling

The shape of shaft furnace is a crucial feature of direct reduction processes, as it affects both particle and gas flow during production. However, current knowledge on the impact of furnace shape on particle flow is limited. Herein, the discrete element method is employed for numerical simulations, in which two different methods of varying the wall angle (i.e., changing the radius or the height) are utilized to investigate the effect of wall angle on the flow behavior of particles in a shaft furnace. The effect of wall angle under different combinations of radius and height on the transformation of the particle flow pattern is innovatively examined, compared to previous studies on charging particles and internal furnace conditions. It is demonstrated in the results that the wall angle of the shaft furnace has a significant influence on the transformation of particle flow mode, with a reduction in the wall angle facilitating the transformation of particle flow mode to mass flow. Furthermore, it is shown in the study that different methods of changing the wall angle have varying effects on the transformation of particle flow mode.     

煤基直接还原炼铁技术分析

分析了主要的煤基直接还原炼铁工艺。回转窑反应温度低,导致动力学条件变差,停留时间长,散热大,吨铁煤耗达到1000 kg左右。从能量利用角度,过多的煤气还需换热加以利用。隧道窑通过罐装矿粉,可省去造球工艺,但是罐子传热只能通过对流与传导换热方式,因此,停留时间长,热量损失大,同时罐子、海绵铁的余热、废气热量尚未得到利用,导致煤耗高达1 500 kg/t海绵铁。转底炉由于温度高,反应速度快,但是热能利用率差,吨铁实际煤耗居高不下。可见,目前的煤基直接还原炼铁工艺,离低能耗、低污染的炼铁目标相差甚远,最大的问题是固态条件下的还原反应效率过低,提高铁矿的低温反应性能是煤基直接还原炼铁走向成功、高效、环保的关键所在。     

气基竖炉直接还原炼铁技术的发展

在分析国内外直接还原铁市场的基础上,探讨了气基竖炉直接还原炼铁技术发展的市场空间。在中国钢铁行业结构调整过程中,气基竖炉技术由于具有节能环保和产品优质的优势,将会成为我国非高炉炼铁发展最重要的方向。从原料、产品、工艺特性、机械设备等方面对MIDREX和Energiron 2种气基竖炉工艺进行了综合比较,探讨了其各自的优缺点。随着技术进步以及全球经济、资源、能源条件的变化,气基竖炉技术正朝着设备大型化、气源多样化、矿源扩大化的方向发展。     

Phosphorus Removal of High Phosphorus Iron Ore by Gas-Based Reduction and Melt Separation

A new method (gas-based separation plus melt separation) has been proposed to remove phosphorus of the high phosphorus iron ore which was 1.25% of phosphorus content and 50.0% of iron content.HSC chemistry package and the coexistence theory of slag structure were adopted for theoretical analysis.The gas-based reduction was carried out using a fixed bed reactor and the ore sample of 80 g with an average particle size of 2 mm were reduced using CO or H2 at temperature of 1073 K for 5 hours.50 g of the reduced...     

煤基直接还原竖炉中熔剂脱硫的热力学和动力学分析

在实验室模拟了煤基竖炉直接还原海绵铁的生产过程，并用化学反应热力学、动力学理论和先进的测试手段对熔剂（白云石、石灰石）脱硫进行研究。结果表明，ＭｇＣＯ３在炉内完全分解，但脱硫效果不明显。虽然ＣａＯ脱硫作用较强，但ＣａＣＯ３只有部分分解。因此，竖炉中加入熔剂后对矿石脱硫有一定影响；熔剂脱硫过程的化学反应和内扩散反应的相对阻力随着脱硫反应的进行而变化；减小熔剂粒径是提高熔剂脱硫能力的有效方法。     

铁精矿氧化球团微波加热直接还原新方法

传统加热直接还原具有热效率低、球团"冷中心"和废热废气量大等问题,造成还原时间长、能耗高和污染大。试验利用微波的选择加热、快速加热、体积加热和清洁干净等优点,以及铁矿球团和无烟煤强的吸波特性,开发了铁矿球团煤基微波竖炉直接还原这一新工艺。研究表明,铁矿球团外配煤粉在1 050℃的微波加热条件下还原焙烧65min,可以获得95.25%的金属化率,同时具有1718.88N/个的抗压强度。与常规加热相比,微波加热还原焙烧的时间可以缩短27.78%,抗压强度增加近1倍,而且还原过程产生的废热废气量很少。     

铁矿石竖炉氢气直接还原温度场模拟

以BL竖炉及工艺参数为计算依据,建立气固传热模型,采用计算流体软件Fluent模拟计算。将球团矿简化为多孔介质,物料的运动采用滑移网格模拟,还原反应采用三步反应参与计算,得到氢气直接还原铁竖炉还原段的温度场,并计算还原气的热效率。结果表明:在一定范围内,随着氢气气量的增加还原段温度梯度逐渐变窄,炉顶气温度逐渐升高,并且还原气的热效率逐渐降低。同时也能够得出还原产物随高度的变化情况。简化的竖炉还原段气固传热模型适用于氢气直接还原竖炉还原段温度场的预测以及炉内反应产物的分析。     

气基竖炉直接还原技术的发展

介绍了Midrex和HyLⅢ气基竖炉技术以及在其基础上开发的可以不依赖天然气直接使用煤制气等作还原剂技术的发展与应用现状,并指出气基竖炉工艺具有能耗低、投资少、产品质量高等特点。     

Analysis of Product Morphologies and Reaction Mechanisms on Gaseous Reduction of Iron Oxides

It is well established that in gaseous reduction processes solid iron oxides exhibit a wide range of reducibilities. Using the interface stability criteria developed to describe the decomposition of metal compounds in reactive gas atmospheres, together with microstructural evidence obtained under well characterised reaction conditions, the relationships between product structures, and the mechanisms and the kinetics of reduction of iron oxides have been examined. It is shown that the structures and reaction rates can be explained through the occurrence of four principal mechanisms; continuous gas pore formation, dense metal layer growth, discontinuous metal layer breakdown and continuous coupled growth of metal and pores. Through identification of the critical conditions for these different mechanisms, the maximum rates of reduction of a given starting material as a function of temperature, thermal history and gas conditions can be more clearly understood.     

煤制气-竖炉生产直接还原铁浅析

以国内磁选铁精矿为原料制备的氧化球团综合性能良好,可作为竖炉直接还原用氧化球团。国内适合于煤气化的褐煤和低变质烟煤资源储量较大,占煤炭资源总量的50%以上,可以满足煤化工发展的需求。综合煤种需求、生产能力、煤气品质以及能耗指标,选取适宜的煤气化工艺,形成以煤制合成气为还原剂,以竖炉为反应器的煤制气-竖炉直接还原炼铁新工艺,是煤资源丰富而天然气匮乏的中国发展直接还原铁生产、实现低碳高效炼铁的有效途径。