Numerical Simulation of Innovative Operation of Blast Furnace Based on Multi-Fluid Model

A multi-fluid blast furnace model was simply introduced and was used to simulate several innovative ironmaking operations. The simulation results show that injecting hydrogen bearing materials, especially injecting natural gas and plastics, the hydrogen reduction is enhanced, and the furnace performance is improved simultaneously. Total heat input shows obvious decrease due to the decrease of heat consumption in direct reduction, solution loss and silicon transfer reactions. If carbon composite agglomerates are charged into the furnace, the temperature of thermal reserve zone will obviously decrease, and the reduction of iron-bearing burden materials will be retarded. However, the efficiency of blast furnace is improved just due to the decrease in heat requirements for solution loss, sinter reduction, and silicon transfer reactions, and less heat loss through top gas and furnace wall. Finally, the model is used to investigate the performance of blast furnace under the condition of top gas recycling together with plastics injection, cold oxygen blasting and carbon composite agglomerate charging. The lower furnace temperature, extremely accelerated reduction rate, drastically decreased CO2 emission and remarkably enhanced heat efficiency were obtained by using the innovative operations, and the blast furnace operation with superhigh efficiency can be realized.

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.

Modeling of the effect of hydrogen injection on blast furnace operation and carbon dioxide emissions

The effect of hydrogen injection on blast furnace operation and carbon dioxide emissions was simulated using a 1D steady-state zonal model.The maximum hydrogen injection rate was evaluated on the basis of the simulation of the vertical temperature pattern in the blast furnace with a focus on the thermal reserve zone.The effects of blast temperature and oxygen enrichment were also examined to estimate coke replacement ratio,productivity,hydrogen utilization efficiency,and carbon dioxide emission reduction.For blast temperature of 1200℃,the maximum hydrogen injection rate was 19.0 and 28.3 kg of H_(2)/t of hot metal(HM)for oxygen enrichment of 2vol%and 12vol%,respectively.Results showed a coke replacement ratio of 3-4 kg of coke/kg of H_(2),direct CO_(2) emission reduction of 10.2%-17.8%,and increased productivity by up to 13.7%depending on oxygen enrichment level.Increasing blast temperature further reduced the direct CO_(2) emissions.Hydrogen utilization degree reached the maximum of 0.52-0.54 H_(2)O/(H_(2)O+H_(2)).The decarbonization potential of hydrogen injection was estimated in the range from 9.4 t of CO_(2)/t of H_(2) to 9.7 t of CO_(2)/t of H_(2).For economic feasibility,hydrogen injection requires revolutionary progress in terms of low-cost H_(2) generation unless the technological change is motivated by the carbon emission cost.Hydrogen injection may unfavorably affect the radial temperature pattern of the raceway,which could be addressed by adopting appropriate injection techniques.

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.

Dust Distribution Study at the Blast Furnace Top Based on k-Sε-u_(p)Model

The dust distribution law acting at the top of a blast fumace(BF)is of great significance for understanding gas flow distribution and mitigating the negative influence of dust particles on the accuracy and service life of detection equipment.The harsh environment inside a BF makes it difficult to describe the dust disthibution.This paper adresses this problem by proposing a dust distribution k-Sε-u_(p)model based on interphase(gas-powder)coupling.The proposed model is coupled with a k-Sεmodel(which describes gas flow movement)and a u_(p)model(which depicts dust movement).First,the kinetic energy equation and turbulent dissipation rate equation in the k-Sεmodel are established based on the modeling theory and single Green-function two scale direct interaction approximation(SGF-TSDIA)theory.Second,a dust particle mnovement u_(p)model is built based on a force analysis of the dust and Newton's laws of motion.Finally,a coupling factor that descibes the interphase interaction is proposed,and the k-Sε-u_(p)model,with clear physical meaning.ligorous mathematical logic,and adequate generality,is dleveloped.Siumulation results and o-site verification show that the k-Sε-u_(p)model not only has high precision,but also reveals the aggregate distribution features of the dust,which are helpful in optimizing the installation position of the detection equipment and imnproving its accuracy and service life.

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.

A novel model for cost performance evaluation of pulverized coal injected into blast furnace based on effective calorific value

The combustion process of pulverized coal injected into blast furnace involves a lot of physical and chemical reactions. Based on the combustion behaviors of pulverized coal, the conception of coal effective calorific value representing the actual thermal energy provided for blast furnace was proposed. A cost performance evaluation model of coal injection was built up for the optimal selection of various kinds of coal based on effective calorific value. The model contains two indicators: coal effective calorific value which has eight sub-indicators and coal injection cost which includes four sub-indicators. In addition, the calculation principle and application of cost performance evaluation model in a Chinese large-scale iron and steel company were comprehensively introduced. The evaluation results finally confirm that this novel model is of great significance to the optimal selection of blast furnace pulverized coal.

Thermodynamic modeling of lead blast furnace

A thermodynamic model was developed to predict the distribution behavior of Cu, Fe, S, O, Pb, Zn, As, and the heat balance in a lead blast furnace. The modeling results are validated by the plant data of a lead smelter in Kazakhstan. The model can be used to predict any set of controllable process parameters such as feed composition, smelting temperature, degree of oxygen enrichment and volume of oxygen-enriched air. The effects of the blast air, industrial oxygen, and coke charge on the distribution of Cu, Fe, S, O, Pb, Zn, As, the heat balance, and the lead loss in slag, were presented and discussed.

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.

Modeling Tensile Strength of Concrete on Partial Replacement of Ce­ment and Sand with Quarry Dust Ground Granulated Blast Furnace and Slag Silica Fumes

Tensile strength of concrete were examined on its partial replacement of cement and sand using ground granulated blast furnace and quarry dust.The study examines its behaviour at different dimensions.This is to monitor the variation effect of these parameters on the growth rates of tensile to the optimum curing age.These include non linear conditions of tensile state,non-elastic and its brittle behaviour at all times as it express zero conditions in tension.This means that it has the ability to with stand pull force.It also reflects its weak ability to handle shear stress thus tends to cause deformation in material as it has poor elasticity.The reflection of its brittle influence the rate of tensile behaviour from concrete ductility.These are known to be a material on modern mechanics of concrete.These are also considered as quasi brittle material.This behaviour was reflected as the system considered evaluating the growth rate of tensile strength that replaced cement and sand with these locally sourced addictives.The developed model monitor other reflected influential parameters such as variation of concrete porosity due it compaction in placements,tensile behaviour reflects these effect that subject it to mechanical properties of concrete.The study expressed the reaction of these parameters in the simulation,the evaluation of these affected the details variation of tensile growth rate at different water cement ratios and curing age.The tensile behaviour that was monitored are based on these factors in the study.The derived model were validated with the a researcher results[24],and both parameters developed best fits correlation.The study is imperative because the system expressed the behaviour of tensile strength from concrete at different dimensions.Experts can applied these concept to monitor tensile behaviour considering these parameters in its growth rates.

Designing for Long Campaign Life Blast Furnace (2)-The Simulation of Temperature Field of Lining and Cooling Apparatus

Through the numerical modeling of temperature field for Blast Furnace (BF) lining and stave coolers, it can tell designers how to design a cooler which the hot surface temperature is less than its critical temperature under very high heat flux. Applying low heat re- sistance lining and staves cooler to BF is good for a layer of slag skull frozen on the hot surface of cooling stave. As long as the slag skull can stand, the furnace wall is stable and the heat loss of furnace does not increase. This is the basic principle for designing long campa- ignship BF.

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.

Numerical Analysis of Blast Furnace Performance Under Charging Iron-Bearing Burdens With High Reducibility

The reducibility of iron-bearing burdens was emphasized for improving the operation efficiency of blast furnace. The blast furnace operation of charging the burdens with high reducibility has been numerically evaluated using a multi-fluid blast furnace model. The effects of reaction rate constants and diffusion coefficients were investigated separately or simultaneously for clarifying the variations of furnace state. According to the model simulation results, in the upper zone, the indirect reduction of the burdens proceeds at a faster rate and the shaft efficiency is enhanced with the improvement under the conditions of interface reaction and intra-particle diffusion. In the lower zone, direct reduction in molten slag is restrained. As a consequence, CO utilization of top gas is enhanced and the ratio of direct reduction is decreased. It is possible to achieve higher energy efficiency of the blast furnace, and this is represented by the improvement in productivity and the decrease in consumption of reducing agent. The use of high-reducibility burdens contributes to a better performance of blast furnace. More efforts are necessary to develop and apply highreducibility sinter and carbon composite agglomerates for practical application at a blast furnace.

Heat distribution model under hydrogen-rich low-carbon conditions in blast furnace

Low carbon development of blast furnaces is one of the key technological directions in the current development of ironmaking.Owing to the differences in the physical and chemical properties of hydrogen and carbon,hydrogen-rich media entering a blast furnace will change the heat distribution,thus affecting the stability of production.Accordingly,a heat distribution model was proposed to study the temperature distribution in a blast furnace,simultaneously considering gas-solid heat exchange,slag and iron melting,and chemical reactions.The model was used to analyze the temperature distribution of a 2300 m^(3) blast furnace and was verified via comparison with actual production data.Subsequently,the effects of the injection rate of hydrogen-rich media,H2 concentration,and oxygen enrichment rate of the blast on the temperature distribution were investigated.Results indicated that the increase in the injection rate of the hydrogen-rich media decreased the amount of direct reduction and led to an increase in the furnace temperature.Furthermore,an increase in the oxygen enrichment rate led to a decrease in the furnace temperature,but could reduce the solid fuel ratio,while the change in H2 concentration had less effect on the temperature distribution.The combination of hydrogen-rich media injection and the increase in the oxygen enrichment rate would help to adjust the temperature distribution to the same level as the conventional blast furnace conditions.

CFD-DEM study on the synergistic effect of coke consumption and particle dynamics in the blast furnace raceway

In this study,the gas-solid flow process in the blast furnace raceway is numerically simulated using coupled computational fluid dynamics and the discrete element method(CFD-DEM).The coke reaction kinetics data are imported into the DEM model to reproduce the consumption process of each coke particle.The effects of inlet gas velocity and angle on the morphology of the raceway,coke consumption rate,coke bed temperature,and particle size distribution in the blast process are systematically investigated and analyzed.The results show that the consumption of coke particles promotes the formation of raceways during the blast process.At the same time,a coke mixture layer is produced at the edge of the raceway.The higher the inlet gas velocity,the thicker the coke mixture layer in the middle and upper parts of the raceway region,and the larger the proportion of small particles in the coke mixture layer.The effect of the inlet gas angle on the raceway region is less than the inlet gas velocity.However,with the increase in the inlet gas angle,the high-temperature region of the coke bed extends downward gradually,which is conducive to activating the hearth.

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.

Physicochemical principles of hydrogen metallurgy in blast furnace

Based on the stoichiometric method and the free energy minimization method,an ideal model for the reduction of iron oxides by carbon and hydrogen under blast furnace conditions was established,and the reduction efficiency and theoretical energy consumption of the all-carbon blast furnace and the hydrogen-rich blast furnace were compared.The results show that after the reduction reaction is completed at the bottom of the blast furnace,the gas produced by reduction at 1600℃still has a certain excessive reduction capacity,which is due to the hydrogen brought in by the hydrogen-rich blast as well as the excess carbon monoxide generated by the reaction of the coke and the oxygen brought in by the blast.During the process of the gas with excessive reduction capacity rising from the bottom of the blast furnace and gas reduction process,the excessive reduction capacity of the gas gradually decreases with the increase in the dydrogen content in the blast.In the all-carbon blast furnace,the excess gas reduction capacity is the strongest,and the total energy consumption per ton of iron reduction is the lowest.This shows that,for the current operation mode of the blast furnace,adding hydrogen in the blast furnace cannot reduce the consumption of carbon required for reduction per ton of iron,but rather increases the consumption of carbon.