Mathematical model of burden distribution for the bell-less top of a blast furnace

Due to the difficulty in measuring the burden trajectory directly in an actual blast furnace （BF）, a mathematical model with Coriolis force and gas drag force considered was developed to predict it. The falling point and width of the burden flow were obtained and analyzed by the model, the velocities of particles at the chute end were compared with and without the existence of Coriolis force, and the effects of chute length and chute torque on the falling point were also discussed. The simulation results are in good agreement with practical measurements with laser beams in a 2500 m3 BF.

Designing for Long Campaign Life Blast Furnace (1)──The Mathematical Model of Temperature Field for Blast Furnace Lining and Cooling Apparatus and New Concept of Long Campaignship Blast Furnace Cooler Design

The physical and mathematical model of temperature field for blast furnace stave coolers was established. The computation results show that the heat resistance of 2-6 mm water scale within the cooling pipe is about 7%-20% of the total heat resistance of cooling stave body, as for drilling duct type, the heat resistance of 2-6 mm water scale is about 88%-98% of the total heat resistance. Using drilling duct or full cast pipe can eliminate gas clearance and coating layer between pipes and cast iron body and reduce the heat resistance of the cooler sharply and improve the coefficient of heat transfer to a great extent. The water velocity within coolers can be kept at the 1evel of 0.5- 1 .5 m/s, the higher water velocity can not decrease the hot surface temperature, but can increase energy consumption for cooling water.

A mathematical model capable of describing the liquid flow mainly in a blast furnace

The molten liquid flow inside a packed bed is a familiar momentum transportation phenomenon in a blast furnace. With regard to the reported mathematical models describing the liquid flow within a packed bed, there are some obstacles for their application in engineering design, or some limitations in the model itself. To overcome these problems, the forces from the packed bed to the liquid flow were divided into appropriate body and surface forces on the basis of three assumptions. Consequently, a new mathematical model was built to present the liquid flow inside the coke bed in a blast furnace. The mathematical model can predict the distribution of liquid flowrate and the liquid flowing range inside the packed bed at any time. The predicted results of this model accord well with the experimental data. The model will be applied considerably better in the simulation on the ironmaking process compared with the existent models.

Mathematical Model of Hearth and Bottom Erosion in Blast Furnace

Furnace lining erosion is closely related to the operation stability and safety. The detection technology for hearth lining thickness of blast furnace was introduced.By using the data of thermocouples installed in the bottom of furnace hearth,a mathematical model of erosion was established; the real state of the hearth and bottom erosion was studied; the erosion condition was followed,serving for the furnace longevity.

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 studies in three aspects:Gas flow and pressure on the liquid surface,and their effect on the drainage characteristics;The flow and temperature distributions of liquid iron in BF hearth,and the temperature distribution in the refractories;Finally,titanium behaviors due to titania injection to form Ti(C,N) -rich scaffold on the hearth surface,to protect the hearth from erosion.

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.

A novel method for modeling the phase change of iron ore particles in the cohesive zone of a blast furnace

Cohesive zone plays a vital role in the stable operation of a blast furnace(BF),yet the complex phase change process of iron ore particles in this zone is still not well understood.In this study,a novel one-dimensional(1D)unsteady phase change model was developed to elucidate the heat transfer and melting mechanisms of iron ore particles.After model validation,the effects of several key operating parameters(e.g.,particle diameter,gas velocity,initial temperature)on the phase change behavior of iron ore particles were analyzed,and the joint effect of multiple parameters was discussed.The results show that larger-sized iron ore particles possess lower specific surface areas,which in turn reduces their convective heat absorption capacity.Consequently,the distance from the solid-liquid phase interface to the particle surface increases,thereby slowing down the movement of the phase interface and pro-longing the melting duration of the particles.Increasing the gas velocity and the initial temperature does not have a significant impact on reducing the duration of the complete melting process.Under the specified conditions,it is observed that increasing the gas velocity by 3-fold and 9-fold results in a reduction of the melting duration by 2.4%and 8.3%,respectively.Elevating the initial temperature of iron ore particles results in a decrease in the core-to-surface temperature difference,a slower heating rate,and a shorter duration to achieve melting.Among the factors affecting the melting process,the particle diameter is found to be the most significant in terms of the liquid phase precipitation,mushy zone thickness,and core-to-surface temperature difference of iron ore particles.

Mathematical Model and Its Hybrid Dynamic Mechanism in Intelligent Control of Ironmaking

A hybrid dynamic model was proposed, which considered both the hydrokinetic and the chaotic properties of the blast furnace ironmaking process; and great emphasis was put on its mechanism. The new model took the high complexity of the blast furnace as well as the effects of main parameters of the model into account, and the predicted results were in very good agreement with actual data.

Numerical simulation for the lower shaft and the hearth bottom of blast furnace

One of the methods forming the shell is to appropriately design the coolingstaves and hearth without overheating during the campaign life of the furnace. The three-dimensionalsteady mathematical models for calculating the temperature distribution in the coolers andtwo-dimensional unsteady mathematical models with phase-change latent heat for calculating thetemperature distribution of the hearth bottom were established. The calculation results show thatthe formation of the slag-metal protection shell can be achieved by optimizing the design parametersof the coolers. Increasing the heat conductivity of the carbon brick can move the isothermal lineof 1150 deg C upward outside the hearth bottom.

Development and Introduction of Monitoring System of Refractory Lining Wear in Blast Furnace Hearth

To diagnose the lining condition of the blast furnace hearth during its campaign, are widely used methods based on the analysis of the temperature characteristics of the refractory lining. Measurement of the temperature characteristics is performed by means of a few hundred thermocouples placed inside the refractory lining. The peculiarity of proposed and used mathematical models is a fully three-dimensional assessment of the refractory lining, presence mechanisms of adaptation to the actual thermal conductivity of refractories and optimization calculations to the work in the on-line mode. The new monitoring systems of the lining wear of the blast furnace hearth are established on 5 blast furnaces of integrated iron-and-steel works of China： No.4 by volume 3,200 m3 of “Jinan Iron ＆ Steel Company” in Jinan （683 thermocouples）, No.2 by volume 1,080 m3 of “Henan Jiyuan Iron ＆ Steel （Group） Company” in Jiyuan （212 thermocouples）, No.4 by volume 2,500 m3 of “Guangxi Liuzhou Iron ＆ Steel （Group） Company” in Liuzhou （383 thermocouples）, No.3 by volume 1,750 m3 of “Jinan Iron ＆ Steel Company” in Jinan （524 thermocouples）; No.1 by volume 1,750 m3 of “Jinan Iron ＆ Steel Company” in Jinan （524 thermocouples）.

Mathematical model of burden distribution in bell-less top blast furnace

The burden distribution in the shaft of blast furnace is known to affect the gas distribution,heat transfer,and chemical reactions inside the furnace.However,the internal layer structure of burden in the shaft cannot be directly measured.Hence,a mathematical model for evaluating burden profile and layer structure was established.A sensitivity analysis based on the model was implemented to elucidate the effect of some factors on the burden distribution,including the stockline height and the mass of central coke.The results show that the width of funnel zone widens with the increase in stockline height,and the mass percentage of ore to coke in this zone slightly increases.Besides,the mass of central coke shows a significant influence on the width of coke channel,and 2%of batch mass of coke is recommended to implement central coke charging operation.The model has been indirectly verified by the gas temperature in operating blast furnace and successfully applied to online evaluate burden distribution.

Investigating effect of coke porosity on blast furnace performance based on multi-physical fields

Reducing coke use is an effective measure to reduce carbon emission and energy consumption in the blast furnace(BF)ironmaking.Essentially,BF is a high-temperature moving bed reactor,where complex physical transformations coupled with complicated reactions occur.This makes it challenging to investigate the factors determining BF performance with the conventional method.A multi-physical field coupling mathematical model of BF was thus developed to describe its mass and heat transfer as well as its intrinsic reactions.Then,the proposed model was validated with the production data.Under coupling conditions,influences of dominating reactions on BF performance(temperature distribution,gas distribution,iron formation reaction,and direct reduction degree)were revealed.The results indicated that coke combustion,indirect reduction,and direct reduction of iron ore mainly took place nearby the shaft tuyere,cohesive zone,and dripping zone,respectively.Besides,the rate of coke solution loss reaction was increased with the rising coke porosity in the cohesive zone.Considering the effect of coke porosity on the efficiency and stability of BF,the coke porosity of 0.42 was regarded as a reasonable value.

沙钢2号高炉低温滑料的原因及治理

沙钢2号高炉进入炉役末期,炉况频繁波动,出现低温滑料现象。通过对高炉已有生产操作数据的总结,认为,因边沿料速快、死焦堆肥大导致软熔带根部到死焦堆距离减小,是引起低温滑料的主要原因。当铁水[Si]含量长时间(4~8h)处于控制标准下限(0.40%~0.45%)以下,并出现大幅度下降(≥0.2%)时,应谨防高炉发生滑料。基于软熔带-死焦堆移动模型,采取将矿批由65.3t提升至67.3t、料速由6.78批/h降至6.60批/h、中心焦比例由25%降至20%边沿两挡矿石圈数从6圈减少至5圈等技术措施后,2号高炉低温滑料次数从月均5次降低至月均2次,治理效果显著。

MgO对烧结工艺及烧结矿冶金性能的影响

研究了MgO对烧结工艺及烧结矿冶金性能的影响。研究结果表明,在烧结过程中不加或少加MgO,可提高烧结生产效率,获得冷态强度高、软熔带温度区间窄的烧结矿,从而提高高炉软熔带的透气性、降低料柱全压差。为保证高炉渣对MgO含量的要求,以及确保烧结矿低的低温还原粉化率,提出了合理添加MgO的新工艺。

长寿高炉炉缸和炉底温度场数学模型及数值模拟

高炉炉缸和炉底的寿命是影响高炉长寿的关键因素之一。实现高炉炉缸、炉底与高炉寿命同步的措施之一就是在高炉炉缸和炉底冻结一层渣铁壳。要想冻结渣铁壳,在高炉设计时应将1150℃等温线推离炉缸和炉底热面,这就需要计算高炉炉缸和炉底的温度场。为此讨论了目前应用于高炉炉缸和炉底温度场的一些数学模型,并在此基础上开发了通用的炉缸、炉底温度场计算软件。

高炉炉身下部及炉缸、炉底冷却系统的传热学计算

在高炉冷却器及炉缸、炉底热面凝结一层渣铁壳有利于防止炉衬侵蚀,延长高炉寿命。为了达到这一目的,需要设计无过热的铸铁冷却壁、铜冷却壁和板 壁结合冷却器以及无过热的炉缸和炉底。为此建立了高炉炉身下部冷却器及炉缸、炉底温度场的数学模型,应用C++语言在VC++集成环境下开发了高炉炉身下部冷却器及炉缸、炉底温度场计算软件。计算结果表明,通过优化炉身下部冷却器及炉缸、炉底的设计参数,能够确保在冷却器热面及炉缸、炉底热面凝结一层渣铁壳。目前,国内一些大型高炉的设计中已采用该软件。

高炉冶炼专家系统的开发研究

介绍了武钢1号高炉专家系统的开发条件、系统结构、数学模型和主要的功能;该专家系统是一种专家系统和数学模型相结合的混合型专家系统,数学模型的计算结果是专家系统开发的基础,利用数学模型和专家系统可以较好地控制高炉生产过程的变化。同时介绍了开发研究的主要成果,如高炉布料控制、炉型管理、炉温控制、炉底侵蚀计算等。系统调试和试用结果表明:该系统可以较好地控制高炉过程,实现高炉的稳定顺行。

高炉冷却壁和炉衬的三维传热模型

本文给出了计算高炉冷却壁和炉衬温度分布的三维稳态传热模型，该模型可用于分析冷却壁不同结构参数（厚度、水管直径、管间距、镶砖厚度和面积等），和不同材料等因素对温度分布和热流密度的影响，它可为冷却壁的设计和炉衬材料的选择提供重要的理论依据。

高炉软熔带气体流动的数值模拟

建立了气体流动的二维轴对称数学模型，对倒Ｖ形软熔带附近的气体流动进行了数值模拟，用阻力比的概念分析探讨了软熔带附近的气体流动，形象地再现了软熔带对气流的二次分布。

基于熵权-可拓理论的高炉软熔带位置状态模糊综合评判方法

针对高炉(Blast furnace,BF)软熔带位置状态影响因素复杂多样且具有层次性和模糊性的特点,提出了基于熵权–可拓理论的高炉软熔带位置状态两级模糊综合评判的新方法.首先,在对高炉生产过程参数进行整理、分类的基础上,采用可拓理论和熵权法确定第一级评判的隶属矩阵和模糊权向量,进行一级模糊评判.其次,以一级评判结果矩阵构成第二级评判的隶属矩阵,并结合层次分析法(Analytic hierarchy process,AHP)确定的第二级模糊权向量,进行二级模糊评判.利用物元的可拓性定性分析和可拓集合论的关联函数定量计算相结合的方法,实现对高炉软熔带位置状态的两级模糊综合评判.最后,以某钢铁厂2 650 m3高炉为实例对其软熔带位置状态进行综合评判,所得结果与现场实际情况吻合良好.