Numerical modeling of multiphase flow,heat transfer and titanium flow behavior in blast furnace hearth

Understanding the complex phenomena in BF hearth is essential to increase furnace productivity and to extend furnace campaign.We have developed several continuum-based mathematical/numerical models to simulate the multi-phase flow,heat transfer and chemical reactions in the BF hearth.These models have generated an improved insight on the mechanisms for liquid drainage efficiency,lining erosion and wall protection in BF hearth under operational conditions.The current paper gives an overview of these studi...     

高炉炉缸内铁水环流与内衬侵蚀

从分析中心焦柱在炉缸内的受力出发，计算了１０００￣５５８０ｍ＾３高炉大喷煤前后中心焦柱在炉缸铁水内的沉入深度，分析了炉缸内铁水环流的产生与炉缸内衬侵的关系，分析表明大喷煤有得利抑制铁水环流对缸内补的冲刷，提出了降低铁水环流对炉缸内衬侵蚀的途径。     

Fuzzy grey relational analysis for influencing factors of heat transfer in a blast furnace hearth

For a blast furnace, the hearth erosion profile is mainly determined by the temperature distribution in the refractory. Numerical simulation was conducted to simulate the heat transfer and flow in a blast furnace hearth. Based on the simulation results, a fuzzy grey relation analysis method combining the grey entropy analysis and Euclidean grey relation analysis was put forward for evaluating the effects of various factors on the temperature distribution of sample areas at the bottom and sidewall refractory. Impacts of four typical factors (porosity of deadzone, floating height of deadman, radius of deadzone and temperature of cooling water) were evaluated by grey entropy analysis and Euclidean grey relational analysis, respectively. Lastly, a fuzzy grey relational analysis was employed to make a comprehensive evaluation of the four factors. Results have shown that the floating height of deadman is the dominant factor affecting the temperature distribution both on the bottom and sidewall.     

高炉炉缸冷却壁对流换热边界的等效置换与导热模型化简

根据固体导热理论讨论大平板和平面轴对称圆筒中对流边界的等效置换问题.利用有限元计算了高炉炉缸冷却壁中水管表面的对流换热边界向内部边界等效置换,给出了算法和计算实例.对流换热边界置换后可使冷却壁一炉墙结构的平面导热问题化为一维问题.     

炉缸侵蚀模型的开发

根据高炉炉缸传热、侵蚀的特点,应用有限元和设计优化技术相结合的方法,并依据炉缸侵蚀模型的计算流程、基本概念,应用APDL开发了高炉炉缸侵蚀模型计算软件,并对该模型调试过程中的关键问题进行了讨论。应用该炉缸侵蚀模型对国内某高炉的炉缸侵蚀曲线进行计算,计算出的炉缸侵蚀曲线与实际情况基本相符。     

Numerical modelling of fluid flow and desulphurisation kinetics in an argon-stirred ladle furnace

A full-scale, three-dimensional, transient CFD modelling approach capable of predicting the three-phase fluid-flow characteristics and desulphurisation behaviour in an argon-stirred ladle was developed. The model can accurately predict the molten steel flow and slag eye behaviour. The predicted sulphur content in ladle as a function of time agrees well with the experimental data. The effects of the initial sulphur content, the gas flow rate and the slag layer thickness on the desulphurisation efficiency were also investigated. The predicted results show that the desulphurisation efficiency improves with the increase of the initial sulphur content, the gas flow rate and the slag layer thickness. Higher gas flow rate can improve the slag–steel interaction, which, in turn, helps improving the desulphurisation rate. The thinner the slag layer, the larger the slag eyes and the smaller the interfacial area between the slag and steel phases. The consequence is the decrease in the desulphurisation rate.     

高炉炉缸炉底侵蚀模型的开发及应用

用有限元法建立了高炉炉缸炉底侵蚀推测二维模型，可在线提供高炉炉缸炉底温度场及侵蚀线图，为高炉安全生产，实现高炉长寿和炉缸炉底的结构参数优化设计提供了依据。     

Simulation of thermochemical and thermomechanical load in blast furnace hearth

All investigations made in the course of the present inquiry aimed at developing proposals for the optimisation of blast furnace bottom and hearth refractories by means of experimental tests. Furthermore, the tests are intended to develop new solutions for prolongation campaign life of blast furnace linings by applying the finite-element method. In the model calculations, particularly those bricks having a high thermal conductivity, showed high resistance to crack and spall formation. In comparison to standard or microporous grades, graphite containing carbon blocks lower the risk of tensile cracks. By additionally doping graphite containing grades with aluminium oxide and silicon, high resistance against pig iron dissolution and infiltration can be reached. Metallurgical coke content proved disadvantageous in the brick, because due to its high porosity the content can be infiltrated additionally into the porous binding matrix. Reduced flow in the brickwork and, thus, reduced convective heat transfer lead to reduced tensile levels in the brickwork. By adapting the pool depth and tap hole length, particularly the linings in the bottom and tap hole area will be relieved thermically. In addition to the required stability of coke particle size and its large particle diameter to ensure an equally distributed pig iron flow through the dead man, the dead man should also have good carburization capacities. When comparing the dissolving inclination by temperature reduction at the internal hearth wall side to the doping influence, it becomes clear that wear can be reduced much more efficiently by adding aluminium oxide than by increasing cooling measures.     

动态渣铁对高炉炉缸陶瓷杯和炭砖的侵蚀

以高炉炉缸常见的2种陶瓷杯和2种高导热炭砖为例,模拟高炉炉缸渣铁流动环境,进行动态渣铁侵蚀试验。从试样的宏观形貌、侵蚀质量、微观结构等方面研究了渣铁对陶瓷杯和炭砖不同的侵蚀作用,对不同的侵蚀区域进行了划分和讨论。研究发现:炉缸砖衬不可避免地会受到直接接触的液态渣铁的侵蚀,对于陶瓷杯,在"渣铁侵蚀区"的侵蚀最为严重,而炭砖的侵蚀较为均匀,不存在"渣铁侵蚀区";试样转速由25r/min提高到50r/min,试样的侵蚀加重,可见渣铁的环流作用会加剧炉缸砖衬的侵蚀。为了抑制渣铁对炉缸砖衬的侵蚀,必须提高砖衬抗渣铁侵蚀能力,同时应维持合理的渣铁流动,减弱炉缸渣铁的环流作用。     

高炉炉缸中心温度偏低的操作

达钢5号高炉一代炉龄后期,高炉冷却系统严重损坏,导致冷却不均匀,高炉加风到一定量时,高炉就会出现管道气流,严重影响高炉的正常生产。通过采用调节风口面积来保证风速活跃炉缸、在原燃料较好的情况下取消中心加焦、在矿石之后或矿石中间加萤石从而保护高炉冷却壁和适当扩大风口进风面积保证风量等方法,使炉缸中心温度逐步回升,高炉抗干扰能力明显增强,高炉各种指标明显好转,从而保证了高炉的稳定顺行,同时也保护了高炉炉衬。     

Numerical investigation on the fluid flow and heat transfer in electroslag remelting furnace with triple-electrode

Electroslag remelting (ESR) furnace with triple-electrode is always used to produce large ingots and the process complexity makes the application not widely spread. Thus, a transient three-dimensional coupled model in industrial scale has been developed to investigate the coupled magneto-hydrodynamics two-phase flow and heat transfer in system. Different from the previous studies with multi-electrode, the current work reveals the triple-electrode ESR with the formation of metal droplets and the solidification of liquid metal. Compared with single-electrode system with the same fill ratio, the heat source in the slag pool with triple-electrode is much more dispersive, and the U-shape metal pool in the ESR furnace with triple-electrode is much shallower and flatter than the V-shaped one in the single-electrode system. A shorter distance from each electrode to the center of system brings a higher heat efficiency, as well as a deeper and narrower metal pool.     

高炉炉缸炉底内衬的等效冷却条件计算方法

建立了高炉炉缸炉底冷却的二维有限元传热模型.该模型能计算紊流水冷冷却器以等效对流换热系数表征的冷却参数,能反解服役炉缸实际冷却强度.等效冷却条件参数可用于缩小多维炉缸传热模型的计算域和规模,且不失边界条件精度.文中设计了参数化有限元建模及分析的计算程序,基于管内紊流水努赛尔特征数,定义一个物性综合系数,构造了更为简明的对流换热系数计算表达式.     

2500m~3高炉炉缸炉底侵蚀监测模型的开发与应用

高炉炉缸炉底是影响高炉寿命的限制性环节之一。为了避免发生严重侵蚀甚至烧穿等重大事故,针对马钢2 500 m~3高炉,开发了利用热电偶或者冷却设备数据监测炉缸炉底侵蚀监测模型。采用该模型,监测了马钢2 500 m~3高炉的炭砖残存厚度变化。该模型可用于判断炉缸炉底是处于侵蚀阶段还是处于堆积阶段,对高炉操作者分析、判断和调节炉况有指导作用。     

高炉炉缸长寿设计理念及长寿对策

通过模型计算、调查和对比分析,就高炉炉缸的长寿问题进行了系统的研究,提出合理冷却强度、建立有效的传热体系、使炉缸尽快形成稳定的渣铁凝固层是炉缸长寿的关键.通过对死铁层深度、炉缸冷却设备、炉缸冷却水系统设计及耐材配置进行研究与分析,提出了微观高水速、高冷却强度,宏观低水量,配合合理的冷却壁结构设计和炉缸耐材配置,建立合理...     

Monitoring and control of hearth refractory wear to improve blast furnace operation

Abstract

Refractory wear and skull growth on the hearth walls and the bottom of the blast furnace have been researched. A series of thermocouples were installed in the hearth, and the temperature measurements were recorded in a structured query language every minute. A heat transfer model was used to study the temperature evolution and hearth wear profile using a commercial software package (MATLAB version 5.0) based on computational fluid dynamics. The location of the 1150°C isotherm in the hearth lining has been calculated. An online monitoring tool was used to analyse the temperature distribution in the hearth and offers, to the plant operators, periodic information on the refractory state. Electromotive force (EMF) probes were installed in the hearth to estimate the variations in the liquid level in the hearth and to determine the thermal state (TS) evolution. Good correlation is seen between EMF and TS, and the EMF amplitudes in the different tapholes follow and even precede the local TS.     

铁水锰含量对高炉炉缸侵蚀的影响

铁水中的锰含量是影响高炉炉缸长寿的因素之一。从黏度和活度系数两方面研究了锰元素对炉缸碳砖的侵蚀机理,并结合2个钢铁厂2 200 m3和1 350 m3的高炉诊断案例进行分析,结果表明:铁水中锰元素的存在会加速对炉缸碳砖的侵蚀;锰元素会降低铁水黏度,加快凝铁层的消失;锰元素还会使碳的溶解度增加,促进铁水对碳砖的侵蚀,建议在生产中尽量控制w(Mn)在0.2%左右。     

Thermodynamic and experimental study of high-temperature roasting of blast furnace gas ash for recovery of metallic zinc and iron

A high-temperature reduction roasting method was used to achieve metallic iron and zinc recovery from blast furnace gas ash(BFA).The reduction processes for Zn-containing and Fe-containing oxides were analyzed in detail by using ther-modynamic equilibrium calculation and the principle of minimum free energy.The results showed that the main reaction in the system is the reduction of ZnFe2O4 and iron oxides.Over the full temperature range,iron oxides were more easily reduced than zinc oxides.Regardless of the amount of CO contained in the system,the reduction of ZnO to Zn was difficult to proceed below the boiling point(906 ℃)of Zn.When the reduction temperature is below 906 ℃,the reduction process of zinc ferrate was ZnFe2O4 → ZnO;when the reduction temperature is above 906 ℃,its reduction process becomed ZnFe2O4 → ZnO → Zn(g).The metallization and dezincification rates of the BFA gradually increased with increasing reaction temperature.As the C/O ratio increased,the metallization and dezincification rates first increased and then decreased.The effect of reduction time on BFA reduction was similar to that of reaction temperature.     

The transfer of silicon from the gas phase to molten iron in the blast furnace

The mechanism of silicon transfer in a blast furnace has been studied. It is concluded that the contribution of slag-metal reaction to silicon increase in the metal will not be very important because of the slow rate of the reaction and high oxygen potential of slag in a blast furnace. By making use of kinetic and thermodynamic data, it is shown that the reaction of SiO containing gas with liquid iron of high carbon content takes an important role in the silicon transfer in a blast furnace.