宝钢高炉炉墙结厚与气液流分布关系的模型研究

通过高炉气体力学模型试验和水电比拟法测定,得到了宝钢高炉炉墙结厚度与气体和炉渣流速之间关系。开发了高炉流场模拟数学模型,并应用该模型从整个高炉的角度探讨了炉墙结厚对气体和炉渣流动的影响;模型研究的结果对炉墙结厚所引起的高炉“上热下凉”现象作出了解释,为制定合理的操作制度,消除结厚,纠正煤气流分布失常提供了理论依据。     

Experimental Studies of Gas‐Liquid‐Powder Flow in Moving Particles

An experimental study has been carried out of gas‐liquid‐powder flow in moving particles in one‐ and two‐dimensional packed beds, simulating the complex four‐fluid flow conditions in an ironmaking blast furnace which involves the upward flow of gas and unburnt coal/char and the downward flow of coke and molten iron and slag. It is shown that the contacts between packed particles are important for powder entrapment, and the presence of a liquid phase can significantly increase the powder hold‐up and gas pressure drop. Only when the packed particles have significant downward velocity can the flow of powder and liquid be maintained without flooding. Depending on the flowing conditions, both steady and unsteady flows can be observed, giving the so‐called operational and non‐operational regimes. For the gas‐glass powder‐water system considered, the effects of solid, liquid, powder and gas flow rates on the two regimes have been quantified. The non‐operational regime stems from the flooding caused by high gas and liquid flowrates and/or hanging caused by high powder and low gas flow rates. The operational regime expands with solid flow rate, and contracts with an increase in gas, liquid and/or powder flow rates. Implications of the findings to blast furnace operations are also discussed.     

武钢5号高炉专家系统在布料状态评估中的应用

高炉布料调剂对于维持高炉的稳定顺行具有决定性的意义。武汉钢铁(集团)公司新开发的5号高炉专家系统利用数学模型实现了高炉布料调剂的自动处理,通过利用数学模型处理高炉操作数据,如炉顶煤气温度、炉顶煤气成分、压差、冷却壁温度变化等,可以获得对气流分布状况、炉型变化状况及高炉运行状况的评估结果;结合高炉当前的运行状况,如焦比、风量、炉身静压力、原料状况(组成、粒度、热性能等)等就可以获得调剂的建议。高炉冶炼专家系统投入运行后,有效指导了高炉的布料调剂,高炉操作稳定,工艺指标得到改善。     

Modeling the discontinuous liquid flow in a blast furnace

This article presents a mathematical model to describe the discontinuous flow of an isothermal liquid in packed beds, simulating in part the flow condition in and below the blast furnace cohesive zone. The model is developed based on a force balance approach to describe the discrete liquid flow and a stochastic treatment to take into account the complex packing structure. The interaction between gas and liquid flows has also been included in the governing equations, so that the localized liquid flow in a packed bed can be modeled with or without gas flow. The difference between the microscopic and macroscopic approaches is discussed, and it is argued that at this stage of development, liquid flow modeling should be conducted at the macroscopic level. Techniques for numerical solution are provided. The validity of the proposed model is demonstrated by comparing model predictions with measurements obtained using a two-dimensional cold model apparatus under different gas and/or liquid flow conditions.     

Influences of scaffold and coal injection on gas and liquid flow distributions in blast furnace: experimental study

Abstract

A laboratory investigation of the gas dynamics and studies using a water–electricity analogue were carried out to clarify the influences of scaffold formation and high coal powder injection on the distribution of gases and liquid slag in the blast furnace. A better understanding of the gas and liquid flow patterns under these conditions was acquired. The applicability of the water–electricity analogue approach to the investigation of liquid slag flow in the blast furnace was proven.     

软熔带对高炉操作的影响

分析了高炉软熔带对高炉生产的影响，探讨了合理软熔带的控制．软熔带的形状与位置是高炉上、下部调剂的综合体现，是决定高炉煤气流稳定运行的关键。为了控制合理的软熔带，应充分考虑自身原料水平，从有利于降低焦比、提高煤气利用水平、高炉顺行、保护炉衬、延长炉龄出发。实现高炉生产效益的最大化．     

渣相组分对高炉炉缸死焦堆滞留率的影响

 为明确高炉炉渣组分对死焦堆中炉渣静态滞留率的影响,采用自行设计的炉渣穿焦试验装置模拟高炉炉渣穿过炉缸死焦堆的过程,探究不同二元碱度(w(CaO)/w(SiO₂))、镁铝比(w(MgO)/w(Al₂O₃))对炉渣滞留率的影响。试验结果表明,随着碱度的增加,炉渣穿过焦炭层的能力增强,滞留率降低;当炉渣镁铝比较低时,炉渣滞留率较高,当镁铝比为0.50～0.55时,滞留率出现最小值,当镁铝比较高时,由于渣焦间润湿性变好,“液桥”间炉渣滞留量增大,滞留率存在上升趋势;渣焦间润湿性较差。炉渣穿过焦炭层的过程主要为物理传输过程,但炉渣仍存在着向焦炭内部渗入的现象,渣焦界面发生反应生成SiC,该反应产物可改善渣焦界面润湿性。     

Bubble and liquid flow characteristics in a wood’s metal bath stirred by bottom helium gas injection

A model study was carried out to elucidate bubble and liquid flow characteristics in the reactor of metals refining processes stirred by gas injection. Wood’s metal with a melting temperature of 70 °C was used as the model of molten metal. Helium gas was injected into the bath through a centered single-hole bottom nozzle to form a vertical bubbling jet along the centerline of the bath. The bubble characteristics specified by gas holdup, bubble frequency, and so on were measured using a two-needle electroresistivity probe, and the liquid flow characteristics, such as the axial and radial mean velocity components, were measured with a magnet probe. In the axial region far from the nozzle exit, where the disintegration of rising bubbles takes place and the radial distribution of gas holdup follows a Gaussian distribution, the axial mean velocity and turbulence components of liquid flow in the vertical direction are predicted approximately by empirical correlations derived originally for a water-air system, although the physical properties of the two systems are significantly different from each other. Under these same conditions, those turbulent parameters in high-temperature metals refining processes should thus be accurately predicted by the same empirical correlations.     

高炉内渣铁焦界面润湿行为研究现状及展望

 高炉作为目前世界上最大的移动床式冶金反应器,保持高炉内良好的透气透液性是保证高炉稳定顺行的关键。高炉内部被软熔带分割开来,分为上部固体散料区和下部固液共存区,下部的固液共存区是决定高炉透气透液性和煤气流分布的重要区域,因此若想明晰高炉影响透气透液性的关键,必须对高炉下部固液共存区的反应进行全面研究。高炉高温区焦炭床与渣铁的相互作用行为是决定铁-焦-渣交互作用及高炉透气透液性的重要因素,调控好液态渣铁与焦炭床的润湿性变化,可以有效改善高炉内部的透气透液性,最终会影响高炉生产效率和稳定性。因此,明晰高炉内渣铁焦的界面润湿行为显得尤为重要。首先对界面润湿现象进行了概述;然后详细从铁水成分以及焦炭性质对铁-焦界面润湿行为的影响进行了总结;其次详细分析了炉渣温度、炉渣成分以及焦炭自身性质对渣-焦界面润湿行为的影响。结果表明,目前高炉内渣铁焦界面润湿行为的研究已经从实验室试验以及基础模拟方面进行了研究,研究结果可为高炉操作者理解高炉内渣铁焦界面润湿行为提供初步理论指导,但仍需在可反映高炉内实际复杂情况的润湿行为变化方面进行深入研究。     

高炉炉墙结厚问题的实践探讨

结合铸管公司3#高炉发生的炉墙结厚问题,指出预防小高炉炉墙结厚应着重抓好精料工作。消除炉墙结厚的主要措施是洗炉,上部可采用强烈发展边缘,利用高炉煤气冲刷融化粘结物,下部以活跃炉缸为主,以改善渣铁流动性。     

底吹炼铜熔池液面波动数值模拟

底吹炼铜是新一代铜强化熔炼工艺。高压气流喷入熔池后产生的液面波动会不断冲刷炉膛壁面,导致壁面耐火材料的磨损。文中利用数值模拟方法对底吹熔池内气液两相流动过程进行研究,分析液面波动导致壁面的压力的变化。通过分析气泡在熔池内的分布及运动过程,得到了熔体对壁面冲刷侵蚀的主要原因。分析壁面压力随时间波动曲线,定义了冲击程度的概念,表征了熔池壁面因波动频率和压力变化而对壁面的磨损程度。模拟计算了单孔氧枪和多孔氧枪的流动过程,得出多孔氧枪气含率更高,冲击程度更小。计算分析了不同参数条件下的流场波动特性,结果表明在实验条件下氧枪角度为0°、气流速为0.7 m/s时,压力冲击程度最小,液面波动对壁面耐火材料的侵蚀最小。      

Analysis on Non‐Uniform Gas Flow in Blast Furnace Based on DEM‐CFD Combined Model

Blast furnace technology is currently aiming at low reducing agent operation so as to decrease CO₂ emissions. At the same time, the inner volume of blast furnaces has frequently been enlarged so as to increase production rate in some countries, including Japan. Operating conditions designed for low reducing agent in a large blast furnace tend to cause unfavorable phenomena such as slipping of the burden and gas channeling due to the decrease in coke rate. Mathematical models help to clarify the in‐furnace phenomena under these situations. From the above backgrounds, a new model has been developed that combines Discrete Element Method with Computational Fluid Dynamics (DEM‐CFD) to simulate precisely the gas flow and solid motion in a blast furnace. The present study aimed to develop a three‐dimensional mathematical model based on DEM‐CFD for simultaneous analysis of gas and solid flow in the whole blast furnace. The unbalanced gas flow in the case of clogging of the particular tuyere was analyzed to clarify the circumferential unevenness in the lower part of the blast furnace. Based on the combined DEM with CFD model, the non‐uniform gas flow in the lower part of the blast furnace was precisely evaluated.     

炉顶煤气循环氧气高炉一维气固换热与反应动力学模型

结合风口回旋区燃烧和炉外煤气预热、脱除和循环的平衡关系,建立了氧气高炉一维气固换热与反应动力学模型,并采用传统高炉的运行和解剖数据对模型进行了验证分析.通过模型研究了氧气含量和上部循环煤气流量对氧气高炉炉内过程变量的影响规律.结果表明:氧气含量偏低和上部循环煤气流量不足时,会降低铁矿石还原效果,炉渣内出现大量未还原铁氧化物;氧气含量和上部循环煤气流量的提高可以有效提高炉内CO含量和铁矿石还原速度,但提高上部循环煤气流量会大幅提升炉顶煤气温度,增大热量损失.与传统高炉相比,氧气高炉内CO含量提高1.0~1.5倍,炉内气体还原性更强;铁矿石还原完成位置提高1.49 m,全炉还原反应速度更快;直接还原度降低55.2%~79.2%,炉内直接还原反应消耗的碳量更少.      

有害元素对焦炭气化反应的影响及展望

摘要：焦炭在高炉冶炼过程中起着重要作用,其中焦炭的气化反应直接关系到其热态强度,并影响高炉内部的透气透液性能。综述了高炉内焦炭气化反应的研究现状,并讨论了焦炭气化反应的评价方法;阐述了有害元素K、Na、Zn和Cl对焦炭气化反应影响的研究进展。指出现有研究多着眼于焦炭和纯CO2或水蒸汽的气化反应,并且冶金工作者对企业通用的焦炭气化反应的测定方法和标准存在不同的看法。K、Na、Zn和Cl均对焦炭气化反应起催化作用,其中K、Na和Zn的催化机理包括氧传递、层间化合物和电子转移3种理论。建议进一步模拟高炉实际气氛和温度条件开展焦炭气化反应的研究工作,并对Cl元素对焦炭气化反应的影响机理进行深入探索。     

钒钛矿冶炼高炉炉缸黏结物的矿相分布规律

摘要：焦炭在高炉冶炼过程中起着重要作用,其中焦炭的气化反应直接关系到其热态强度,并影响高炉内部的透气透液性能。综述了高炉内焦炭气化反应的研究现状,并讨论了焦炭气化反应的评价方法;阐述了有害元素K、Na、Zn和Cl对焦炭气化反应影响的研究进展。指出现有研究多着眼于焦炭和纯CO2或水蒸汽的气化反应,并且冶金工作者对企业通用的焦炭气化反应的测定方法和标准存在不同的看法。K、Na、Zn和Cl均对焦炭气化反应起催化作用,其中K、Na和Zn的催化机理包括氧传递、层间化合物和电子转移3种理论。建议进一步模拟高炉实际气氛和温度条件开展焦炭气化反应的研究工作,并对Cl元素对焦炭气化反应的影响机理进行深入探索。     

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.     

A fundamental study of raceway size in two dimensions

Blast furnace raceway zones are formed by the force of the air blast injected through the tuyeres evacuating a region of the packed bed directly in front of these tuyeres. Raceway depths in blast furnaces have been historically predicted through the use of empirical correlations based on measurements on cold and hot models. These correlations are not found to be universal in application, however, with many researchers finding only fair agreement between their experi-mental data and the correlations proposed by other researchers. We present here an alternative physical mechanism approach for raceway formation based on examination of the fundamental properties of the system. The study includes two-dimensional experiments where raceway depths and shapes are measured and an accompanying theoretical and numerical analysis of the under-lying mechanisms. Gas flow distributions around the raceway zone are also examined. It is found that the raceway size for given blast conditions and particle properties is such that the total gas drag on the solids vertically above the raceway balances the solid bed weight, with some allowance for solid holdup by walls. The formulation of this theory leads to the further conclusion that the total surface area of the raceway walls as a fraction of the horizontal cross-sectional area of the container or furnace is a unique function of three factors: (a) the gas flow rate as a fraction of the gas flow rate required to fluidize the bed, (b) a particle Reynolds number calculated at the particle's incipient fluidization velocity, and (c) the shape of the horizontal cross section of the bed.     

HIsmelt主反应器传热数值模拟研究进展北大核心CSCD

HIsmelt作为新兴非高炉炼铁工艺之一,得益于其在原料、工艺以及环境等方面的突出优势,迅速成为各个钢铁行业关注的焦点。然而,在工业试验与实际生产过程中发现,HIsmelt主反应器烟气温度过高而铁水温度较低,相比高炉而言,其上下部换热效率有待进一步提高。通过对HIsmelt炉内换热数值模拟的相关研究进行回顾,从矿石预处理入手,再到渣铁熔池和流场射流2个区域,对不同操作及设计参数下的炉内换热模拟过程进行综述。分析探讨了其模拟流程优缺点及后续研究方向,期望可以促进HIsmelt主反应器上下部热量高效传递,提升HIsmelt工艺热量利用效率,推动HIsmelt流程在中国平稳发展。