Language：Japanese   Publisher：The Iron and Steel Institute of Japan  

<p>Slag foaming is a phenomenon caused by the generation of CO bubbles due to the reaction between iron oxide in slag and carbon in pig iron. The purpose of this study is to explore the controlling factors of slag foaming by observing the bubble formation behavior caused by the chemical reaction between iron oxide and Fe-C alloy in slag. 0.06 g of Fe-C alloy was charged to the bottom of the BN crucible, and 6.0 g of slag (SiO₂:CaO:Fe₂O₃ = 40:40:30) was charged on top of it. The crucible was placed in an infrared image heating furnace, and the temperature was rapidly raised to 1370°C at a rate of 1000°C/min in a N₂ stream, then held for a predetermined time and rapidly cooled. After rapidly cooling, the internal structure of the sample was observed using a high-resolution X-ray CT device. The spherical equivalent volume is calculated based on the number of bubbles observed and their equivalent circle diameter, and the relationship between the volume ratio of small bubbles in the slag volume and the distance from the bottom of the crucible is calculated, and the bubble density and volume ratio are calculated. It was suggested that the value tends to increase as the distance from the bottom of the crucible increases.</p>

DOI： 10.2355/tetsutohagane.tetsu-2023-093

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CiNii Research

Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： https://doi.org/10.2355/isijinternational.ISIJINT-2023-160

Language：English   Publishing type：Research paper (scientific journal)  

Cu-ZnO-Al2O3 catalyst was prepared by introducing fine bubbles of ammonia into a mixed aqueous solution of metal nitrates under carbon dioxide flow and its activity was tested for the methanol decomposition reaction. Specific surface area of the newly developed fine bubble catalyst (FBC) was 94 m(2)/g and 1.5 times larger than that of conventional catalyst (CVC) prepared by co-precipitation of mixed metallic aqueous solution and sodium carbonate. SEM revealed that the FBC particles were spherical of around 3 mu m diameter and homogeneous. The particles of CVC were irregular in size and shape. SEM-EDX showed aggregation of copper in the CVC but good dispersion of all elements in the FBC. FBC had higher activity and less deactivation in the methanol decomposition reaction compared with CVC even at 623-673 K although the reaction time was only 10 hours.

DOI： 10.1627/jpi.64.132

Language：English   Publishing type：Research paper (scientific journal)  

Novel Fe-Mn soft magnetic powders produced by the wet method and hydrogen reduction have been developed for electric motor applications. Aiming to clarify the magnetic properties and associated mechanism, the state of doped Mn in Fe-Mn soft magnetic powders was analyzed in this work. X-ray absorption fine structure spectroscopy (XAFS) was used to detect the presence of manganese as a solid solution in the body-centered cubic (BCC) iron phase of Fe-Mn powders. Although the presence of manganese in the BCC iron phase typically reduces magnetization and increases coercivity, the Fe-Mn powders exhibited coercivity values below approximately 80 A/m, and the saturation magnetization of the Fe-Mn powders was comparable to that of bulk pure iron (218 A m(2)/kg). Because MnO is typically resistant to reduction under hydrogen at 1373 K, the results of this study suggest that elements that are difficult to reduce using hydrogen might be doped in a metallic state by using the wet method. This method is promising to produce novel soft magnetic materials and base materials for soft magnetic composites. (C) 2020 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jallcom.2020.157983

Language：Japanese   Publishing type：Research paper (scientific journal)  

Woody biomass is gasified with iron ore. The amounts of flammable gas products are not changed and only carbon dioxide are increased when iron ore exists. Iron ore in the residue of gasification reaction is almost reduced to metal iron. The amounts of tar and char are decreased at same time. Therefore, it is considered that iron ore is reduced by tar and char. When gasification of woody biomass is conducted under carbon dioxide atmosphere, the amount of carbon dioxide exhausted is lower than that of supplied. During gasification, carbon dioxide is reduced to carbon monoxide. This phenomena is important that this result means realization of negative emission. About 66% of iron ore is reduced to metal iron even under carbon dioxide atmosphere. More than 90% of energy of biomass is recovered when chemical potential of reduced metal iron is included.

Language：English   Publishing type：Research paper (scientific journal)  

In the bottom region of blast furnaces during the ironmaking process, the liquid iron and molten slag drip into the coke bed by the action of gravity. In this study, a practical multi-interfacial smoothed particle hydrodynamics (SPH) simulation is carried out to track the complex liquid transient dripping behavior involving two immiscible phases in the coke bed. Numerical simulations were performed for different conditions corresponding to different values of wettability force between molten slag and cokes. The predicted dripping velocity changes and interfacial shape were investigated. The relaxation of the surface force of liquid iron plays a significant role in the dripping rate; i.e., the molten slag on the cokes acts as a lubricant against liquid iron flow. If the attractive force between the coke and slag is smaller than the gravitational force, the slag then drops together with the liquid iron. When the attractive force between the coke and slag becomes dominant, the iron-slag interface will be preferentially detached. These results indicate that transient interface morphology is formed by the balance between the momentum of the melt and the force acting on each interface.

DOI： 10.3390/pr8020221

Language：English   Publishing type：Research paper (other academic)  

We have previously reported a study of novel Fe-Mn powders doped with 0.1-0.2 at.% manganese prepared by the reduction of (Fe1-x, Mn-x)(3)O-4 nanopowders using hydrogen gas. We detected the presence of manganese in bcc iron phase in the Fe-Mn powders using X-ray absorption fine structure spectroscopy. The Fe-Mn powders exhibited coercivity values ranging between 0.1 and 1 Oe. The saturation magnetization of the Fe-Mn powders was comparable with that of bulk pure iron, i.e., 218 emu/g. The presence of manganese in bcc iron phase should normally reduce the magnetization and increase coercivity. We discuss the relationship between the magnetic properties and structure of the Fe-Mn powders investigated via detailed magnetization measurements, analysis using, transmission electron microscopy, and X-ray absorption fine structure spectroscopy.

DOI： 10.1007/978-3-030-36296-6_57

Language：English   Publishing type：Research paper (scientific journal)  

For blast furnace iron-making, understanding the flow behavior of molten iron and slag on the surface of metallurgical coke will lead to optimal design of burden material, which strongly influences the gas permeability of the furnace. Since the surface structure of coke changes as the reaction of carbon with CO2 or iron oxide progresses, wettability and motion of liquid in the coke-packed bed may be influenced depending on the reaction ratio of coke, i.e., the surface structure. In the present study, to investigate the influence of the surface structure of coke on liquid flow behavior, the advancing and receding contact angles of mercury and water on coke were measured. Of the two liquids, mercury has the higher surface tension. The surface structure of the coke substrate was varied by heating in CO-CO2 or CO2 atmospheres at 1273 K. It was found that the fine irregularities of the coke surface formed by the gasification reaction of the carbon increases the receding contact angle of water but has little influence on the dynamic contact angle of mercury. Depending on the results, influence of surface property of coke on flows of molten iron and slag in the blast furnace is discussed.

DOI： 10.2355/isijinternational.ISIJINT-2017-008

Language：English   Publishing type：Research paper (scientific journal)  

In ironmaking, maintaining gas permeability in blast furnace with low coke rate operation is essential to reduce carbon emissions. The high pressure loss in the cohesive zone decreases the gas permeability and affects the productivity of blast furnace. In order to increase the gas permeability in the cohesive zone, the thickness of the cohesive layer should be decreased. For this purpose, increasing softening temperature and decreasing dripping temperature of the iron ore are desired. In this study, softening, melting, and permeation of SiO2-FeO-CaO-Al2O3-MgO on a coke bed were investigated. The oxide sample in a tablet form was heated under CO/CO2 atmosphere, and the shape of the tablet was observed. The softening and melting temperatures of the SiO2-FeO-CaO system changed with the addition of Al2O3 and MgO. Oxide tablets with and without Al2O3 softened below and above the solidus temperature, respectively. The melting temperatures varied with the ratio of CO/CO2 in the gas. The permeation temperature was independent of the melting temperature, but dependent on the wettability.

DOI： 10.1007/s11663-016-0683-0

Language：English   Publishing type：Research paper (scientific journal)  

Owing to powder accumulation in the packed bed, the permeability of gas and liquid deteriorates, which decrease throughput of the blast furnace. Powder in the moving bed has a large effect on the productivity and efficiency of the blast furnace process when operating with low coke rate and using high-reactivity coke. Therefore, an investigation on the effect of the powder's physical properties and the moving bed material on transport phenomena and the accumulation mechanism of powder in the blast furnace is essential.
In the present study, the motion of powder particles was simulated using the discrete element method (DEM), and the effect of the powder particles' shape on the behavior and accumulation of powder was investigated. The study used DEM to reproduce the movement of particles by solving the equations of motion of individual particles. Since the particles were treated as spherical objects in DEM, contact friction and rolling resistance were implemented to represent the irregular shape of actual powder particles. The calculation results showed that contact friction and rotational resistance affected the static holdup of the powder. The amount of clogging of powder at a bottleneck in the moving bed increased with increasing coefficients of friction and resistance. Moreover, the impact of the flow velocity of the gaseous phase on the accumulation behavior of powder was examined. The frictional force on powder particles at the bottleneck increased with an increase in the gas velocity. The clogging of powder occurred easily as a result.

DOI： 10.2355/isijinternational.55.1313

Language：English   Publishing type：Research paper (scientific journal)  

For the low carbon operation of blast furnace, it is necessary to maintain the gas permeability in the furnace at low coke rate. The pressure drop in the cohesive zone of the blast furnace is significantly high, and the gas permeability of the cohesive zone has an influence on the productivity of the iron-making process. The gas permeability increases as the thickness of the cohesive zone decreases. The present study aimed to decrease the thickness of the cohesive zone by achieving a higher softening temperature and a lower temperature for the dripping of the sinter ore. The softening, melting, and permeation processes of CaO-FeO-SiO2 oxide on a coke bed was investigated. The change in the shape of the oxide tablet, the formation of the liquid droplet, and its permeation into the coke bed were observed with increasing temperature in several CO/CO2 atmospheres. Softening of the oxide was observed at a temperature that was slightly above the solidus temperature. The deformation of the oxide tablets was strongly affected by the liquid phase ratio. Furthermore, there was no relationship between the temperature of permeation and the melting of the oxide tablet. The permeation of the oxide melt into the coke bed is dependent on the wettability between them.

DOI： 10.2355/isijinternational.ISIJINT-2015-269

Language：English   Publishing type：Research paper (scientific journal)  

To mitigate CO2 emission from a blast furnace, the use of H-2 as a reducing agent is considered to be a prominent method. Reduction of iron ore was reported to be improved by H-2 addition. In the present research, reduction in a sinter-packed bed by CO and H-2 was carried out under various oxygen partial pressures, and the influence of reduction atmosphere on the reaction behavior was investigated. It was confirmed that the reduction rates were higher when using H-2/H2O and CO/CO2/H-2/H2O mixtures than when using a CO/CO2 gas mixture. The reaction rate constant for iron ore reduction was determined from the experimental result using a numerical model. The influence of the water-gas shift reaction on the reduction rate was analyzed by comparing the results obtained using the numerical model and those in the experiments. Moreover, the longitudinal distribution of the reaction rate in the packed bed was analyzed to examine the influence of the water-gas shift reaction.

DOI： 10.2355/isijinternational.55.1213

Language：English   Publishing type：Research paper (scientific journal)  

Maintaining gas permeability is an important issue to realize low coke rate operation of blast furnace. In present study, the melting behavior of the iron ore and the layer structure in low coke rate operation were introduced in to the DEM-CFD model, and then behaviors of gas and moving bed in the blast furnace were simulated. Influence of shape of cohesive zone in low coke rate operation was investigated, and the effect of coke slit in the cohesive zone on gas flow was demonstrated in the calculation result. Surface area of cohesive zone and intersection angle between the burden layers and cohesive zone will determine the activity of coke slit.

DOI： 10.2355/isijinternational.55.1232

Language：English   Publishing type：Research paper (scientific journal)  

Liquid dripping in a packed bed of coke in a blast furnace decreases the gas permeability and production stability. Enhancing the liquid flow is desirable to increase the productivity of the blast furnace process. The wettability between the liquid and coke affects the dripping behavior. In present study, the contact angle of a moving droplet on a non-smooth solid surface was investigated considering dripping slag and pig iron droplets in a packed bed of coke. The advancing and receding contact angles of water and mercury on a substrate were measured at room temperature while controlling the wettability and roughness. The angles between the cut surface of the coke and water or mercury were also measured. The roughness of the solid surface affected the movement of the adhering droplets, but the effect of the roughness was significantly altered by the wettability. It was found that the resistance to movement of the liquid increased and decreased under good and poor wettability conditions, respectively. Because the wettability of the liquid phase in the blast furnace changed depending on the temperature and composition of molten slag or iron, the force on a liquid droplet from the coke surface changed depending on the position and composition of the hot metal and molten slag in the coke bed.

DOI： 10.2355/isijinternational.55.1277

Language：English   Publishing type：Research paper (scientific journal)  

A low coke rate operation of a blast furnace tends to cause deterioration of the gas permeability. The liquid iron and molten slag dripping under the melting zone influences the gas flow and permeability in the lower part of the furnace. A computational fluid dynamic model, using a particle-based simulation, is presented for characterization of the melt dripping behavior in a packed bed. In this work, the validity of the liquid passing conditions based on the gravity to surface tension ratio was confirmed. The melt shape produces an "icicle," "droplet," and "dome" forms based on the change of the surface tension and density absolute values. Even with an identical liquid volume passage, the form of the liquid flow changed by the pressure from the liquid's upper portion. Even if it has identical gravity and surface tension ratios, the liquid flow changes with the volume of the liquid phase and its form.

DOI： 10.2355/isijinternational.55.1259

Language：English   Publishing type：Research paper (scientific journal)  

Liquid flow in blast furnaces has a significant influence on gas flow and pressure drop. Therefore, the stability of blast furnace operations and productivity are affected by liquid flow. In a furnace, liquid flows in a packed bed, consisting of coke. Holdup is an important phenomenon in packed bed flow. It changes with the variation of the packed bed structure and the physical properties of the liquid. In this study, a numerical simulation for packed bed flow is carried out. The effects of a packed bed structure on holdup phenomena were analyzed by the moving particle semi-implicit (MPS) method.

DOI： 10.2355/isijinternational.55.1284

Language：English   Publishing type：Research paper (scientific journal)  

Liquid and Powder Motion in Packed bed
8133

DOI： 10.11395/jjsem.14.s237

Language：English  

From the backgrounds of the recent trends towards low reducing agent operation of large blast furnaces and application of diversified charging modes for various burdens, an advanced mathematical model of the blast furnace is required. Although conventional models based on the continuum model have been widely used, these models are not sufficient for the recent demands. Discrete models such as discrete element model (DEM) and particle method are expected to enable precisely simulation of the discontinuous and inhomogeneous phenomena in the recent operating conditions. With discrete models, microscopic information on each particle in the packed bed can be obtained in addition to the overall phenomena in the blast furnace. Visual information for understanding in-furnace phenomena can be also obtained with high spatial resolution. Liquid dripping and the movement of fines in the lower part of the blast furnace can be simulated with high accuracy by using DEM and particle methods such as the Moving Particle Semi-implicit Method (MPS). Moreover, the optimum bed structure for low reducing agent operation is being clarified by application of the Eulerian-Lagrangian method. This review summarizes recent progress on the mathematical models based on the discrete model.

DOI： 10.2355/isijinternational.54.1457

Language：English   Publishing type：Research paper (scientific journal)  

In ironmaking high temperature processes, solid, liquid, and gas phases coexist and interact one another. The gas flow in a packed bed containing liquid and powder depends on their distributions, and the packing structure. Some parts of the liquid and powder phases passing through of the packed bed accumulate. Excessive accumulation may clog the gas flow in the packed bed. The flow and accumulations behaviors of powder and liquid phases coexisting in a packed bed have yet to be clarified.
Thus the phenomena of liquid and powder accumulation and clogging were experimentally investigated in the present study. The effect of the wettability and powder diameter on their accumulation was mainly studied. The results revealed that the wettability of packed material with liquid had significant effect on the accumulation of powder through the form of the liquid holdup.

DOI： 10.2355/isijinternational.54.1244

Language：Japanese   Publishing type：Research paper (scientific journal)  

With the aim to decrease the reducing agent rate in blast furnace, the use of ferro coke containing metallic iron as a catalyst was proposed. This new burden material is expected to lower thermal reserve zone temperature. For the production of ferro coke, the use of a vertical coke oven is examined to realize the optimum carbonizing process. In this type of the oven, the burden materials have a distribution in residence time due to the friction effect on the wall and the interaction between the burdens. It has a great influence on the properties and quality of the ferro coke. Increasing the size of the vertical coke oven is essential for producing a large amount of ferro coke efficiency with stable quality. In this study, the burden descending behavior in an enlarged vertical coke oven was calculated by Discrete Element Method (DEM). The effects of the shape of the discharging part and the discharging method on the residence time of the burden were analyzed based on the calculated results. In addition, considering the reinforcement of the enlarged coke oven, the burden descending behavior in the vertical coke oven with reinforcing horizontal beam inside was also examined.
The calculation results showed that distribution variation in the residence time could be decreased by increase in the size of the vertical coke oven. Furthermore, the results showed the possibility of controlling the residence time by controlling the discharge method.

DOI： 10.2355/tetsutohagane.100.593

Language：Japanese   Publishing type：Research paper (scientific journal)  

From the backgrounds of the recent trend towards low reducing agent operation of large blast furnace and application of diversified charging modes of various burdens, an advanced mathematical model of blast furnace is required. Although conventional models based on the continuum model have been widely used, these models are not suitable for the recent demands. The discrete models such as discrete element model (DEM) and particle method are expected to precisely simulate the discontinuous and inhomogeneous phenomena in the recent operation conditions. With the discrete model, the microscopic information on each particle in the packed bed can be obtained besides the overall phenomena in blast furnace. The visual information can be obtained to understand the in-furnace phenomena with high spatial resolution. The liquid dripping and movement of fines in the lower part of blast furnace can be well simulated with DEM and particle method such as Moving Particle Semi-implicit Method (MPS). Moreover, the optimum bed structure for low reducing agent operation is being clarified by application of Eulerian-Lagrangian method. This review summarizes the recent progress on the mathematical model based on the discrete model.

DOI： 10.2355/tetsutohagane.100.198

Language：English   Publishing type：Research paper (scientific journal)  

Reduction of the reducing agent aiming at the mitigation of carbon dioxide emissions decreases the gas permeability in blast furnace. Favorable control of burden distribution and optimization of packed bed might mitigate decreasing permeability. Especially, decreasing thickness of cohesive zone would be effective. In present study, the influence of the cohesive zone thickness on gas flow and pressure distribution was investigated using the DEM-CFD model to evaluate the effects of adoption of a thin-layered cohesive layer structure on gas flow and permeability changes in the cohesive zone during low coke ratio operation. Reducing the thickness of the cohesive zone can effectively increase permeability in the cohesive zone even in the thin coke slit of the low coke rate operation, and improvement in the permeability of the cohesive zone can be realized more effectively in combination with appropriate coke mixed charging.

DOI： 10.1002/srin.201300025

Language：English   Publishing type：Research paper (other academic)  

Analysis of a Liquid Flow In a Blat Furance for Low Coke Rate Operation

Language：English   Publishing type：Research paper (other academic)  

Issue for Achievement of Low-Carbon Blast Furnace Operation

Language：English   Publishing type：Research paper (other academic)  

Effect of wettability on the accumulation of powder

Language：English   Publishing type：Research paper (other academic)  

Modeling of liquid flow in the lower part of blast furnace by MPS method

Language：English   Publishing type：Research paper (scientific journal)  

A low coke rate operation in blast furnace is desired to decrease the carbon input and mitigate global warming problem. However, low coke rate operation tends to cause the gas permeability to deteriorate. The mixing of small-size coke (nut coke) including high reactivity coke in ore layer is considered to be a promising way to improve permeability and increase reaction efficiency in a blast furnace. Although adding a nut coke mixing to an ore layer is predicted to be empirically effective in low coke rate operation, there is little actual data on microscopic phenomena of each particle in the packed bed. In the present study, an Euler-Lagrange approach was introduced to precisely understand the influence of the packed bed structure on the reaction behavior of each particle in the three-dimensional particle arrangement.
It was observed that the heterogeneity on the reaction rate and temperature distribution was influenced by the particle arrangement. When high-reactivity coke was used at approximately 1 273 K, although CO gas fraction increased, the gaseous phase temperature decreased due to the active solution loss reaction rate of the nut coke in the mixed layer. As a result, the ore reduction rate decreased. The contribution of high-reactivity coke to the ore reduction rate depends on the particle arrangement through the heat transfer and reaction heat. Accordingly, in the case of the mixed charge of the high reactivity nut coke in the ore layer, the design of the packed bed structure is important.

DOI： 10.2355/isijinternational.53.1770

Language：English   Publishing type：Research paper (other academic)  

Simulation Model of Powder Movement in Packed Bed by Discrete Element Method

Language：Japanese   Publishing type：Research paper (scientific journal)  

To decrease the reducing agent ratio in the blast furnace, various measures such as mixed charging are being pursued. Coke mixed charging is considered to improve permeability in the cohesive zone and the reducing behavior of ore particles. Conventionally, these researches were frequently carried out with a small packed bed. However, the information obtained by these experiments was based on a macroscopic analysis. In the present research, a DEM-CFD model developed by the authors was applied to precisely analyze reaction behavior under various packed bed structures, such as that with coke mixing. Moreover, the effect of high reactivity coke on the reduction rate of ore was examined using this model. According to the results, coke mixed charging has little influence on the reduction rate. When high reactivity coke was charged to the ore layer, the particle temperature decreased due to the endothermic reaction by high reactivity coke. Accordingly, the reduction rate of the ore particles was suppressed as a result of the temperature change. This phenomenon was relatively noticeable in the packed bed structure with high reactivity coke set up in the lower part.

DOI： 10.2355/tetsutohagane.99.391

Language：English   Publishing type：Research paper (scientific journal)  

Low reducing agent operation of the blast furnace has an important role in mitigating carbon dioxide emissions in the steel works. Low reducing agent operation results in a low coke rate in the blast furnace. In low coke rate operation, the permeability in the blast furnace is considered to change remarkably due to the increase in the ore-to-coke (O/C) ratio. Charging methods based on conventional layered charging should be improved to a new method such as coke mixed charging. In this study, a DEM-CFD model considering the softening behavior of ore particles in the cohesive zone was applied to evaluate the gas flow in low coke rate operation. First, the softening melting test was simulated by the overlapping of particles in DEM. The layer structure and void fraction distribution in the blast furnace were calculated for normal coke rate and low coke rate operation by DEM. Second, gas flow behavior was analyzed by the DEM-CFD model, focusing on the cohesive zone. From the results, it was estimated that the gas flow was influenced by the coke slit structure in the cohesive zone and the permeability of ore layers mixed with coke particles. Under the normal coke rate of 350 kg/t, coke mixed charging has little effect on permeability through the thin coke slit. However, in low coke rate operation, coke mixing can improve the permeability of the cohesive zone.

DOI： 10.2355/isijinternational.52.1990

Language：Japanese   Publishing type：Research paper (scientific journal)  

For the sake of reduction of reducing agent in blast furnace, the use of ferro coke containing metallic iron as a catalyst was proposed to control the thermal reserve zone temperature. To produce ferro coke, the vertical type of coke oven is used to realize the optimum carbonizing process. In the vertical type coke oven, it is estimated that each particle has a specific residence time derived from the friction effect to wall and the interaction of particles. These phenomena have a great influence on the properties of Ferro coke. In this study, the observation of descending behavior in the packed bed was carried out with cold model. The movements of descending particles were analyzed with DEM calculation for cold model and pilot plant. It was found that the friction effect between wall and particles caused the delay of descending speed on the corner of the furnace. Moreover, the mixing effect of particles during descending was studied with the application of diffusion model, using DEM calculation. The residence time distribution model for the vertical type coke oven was newly developed. On the basis of these results, the descending behavior in the pilot plain was clarified.

DOI： 10.2355/tetsutohagane.98.459

Language：English   Publishing type：Research paper (scientific journal)  

The liquid flow in the packed bed strongly affects the productivity and operational stability of the blast furnace. It is controlled by the physical properties and wettability of the melt and the structure of the packed bed. However, this is a difficult object of analysis, as melt properties and conditions in the furnace are inhomogeneous. In this research, a three-dimensional model of the liquid flow in a packed bed was constructed using the MPS method, which is one of particle method, in order to express melt behavior. The liquid flow on solid surfaces was expressed by optimizing the relationship of energy at a three-phase (solid, gas, liquid) interface. The appropriateness of the calculation model was verified by analyzing and comparing the behaviors of liquids with different physical properties flowing on the surface of a single sphere experimentally and in calculations. Next, this model was applied to analysis of the flow of liquids dripping in a packed bed, and a simulation was calculated for a three-dimensional liquid flow comprising dispersion and coalescence of the liquid. Among the knowledge obtained in this study, the viscosity of a liquid migrating through a packed bed influences the velocity and flow path of the liquid, but has little effect on the amount of liquid which remains in a static condition in the packed bed.

DOI： 10.2355/isijinternational.52.1565

Language：Japanese   Publishing type：Research paper (scientific journal)  

Low reducing agent operation of large blast furnace has attracted a special attention from the background of the global warming. Because the coke ratio is reduced in this operation, causing a huge local ventilation resistance that causes operational problems, it has become increasingly necessary to understand the operation of blast furnace based on non-empirical phenomena. Among the most promising numerical approaches is a combination of the discrete element method (DEM) and computational fluid dynamics (CFD). In this study, particle-based model was newly developed, which considers heat transfer, mass transfer and chemical reactions in the shaft part of blast furnace. It became possible to analyze the three-dimensional discontinuous phenomena among particle with gas flow.
Because this model was developed to expand the spatial scale more than conventional analysis, the discontinuous factors made it possible to simulate by the behavior of discrete particles. The particle arrangement and the packed bed structure were evaluated for studying the flow structure, temperature and composition distribution. Remarkable change in the heat and mass transfer characteristic appeared in the interface between coke and ore layer, and near the wall. The ore and coke particle mixture system, which was expected to improve reducing rate due to the dense packing, is relatively-ineffective. Rather, a low permeability resistance improved reducing rate, it means convection effect was larger. Degree of freedom of particle arrangement is high, and its large influence on temperature and reaction distribution, it was able to show the usefulness of this model.

DOI： 10.2355/tetsutohagane.98.341

Language：English   Publishing type：Research paper (other academic)  

Advanced gas-solid flow simulation in blast furnace by Eulerian-Lagrangian approach

Language：English   Publishing type：Research paper (other academic)  

Modeling of liquid flow in the lower part of blast furnace by particle method

DOI： 10.2355/isijinternational.51.41

Language：English   Publishing type：Research paper (other academic)  

Enhancement of reducing agent reactivity for mitigating CO2 emissions from ironmaking process

Language：English   Publishing type：Research paper (scientific journal)  

Since the cohesive zone has a great influence on the gas flow in the blast furnace, modeling of the cohesive zone is considered to be an important subject. In the cohesive zone, the softening and melting behavior of ore particles is affected by the load from the upper layer and the temperature distribution, and the pressure drop of the ore layer increases remarkably due to shrinkage of the ore particles. In this study, a model of the cohesive zone considering physical properties such as Young's modulus was developed on the basis of the discrete element method, which can track the individual motions of the numerous particles in a packed bed. To determine the appropriate Young's modulus of ore particles for the cohesive zone, element model calculations for a softening test under load were carried out, with particular attention to change in the void fraction. The optimized value of Young's modulus value was then introduced in the discrete element method and computational fluid dynamics (DEM-CFD) model. The changes of gas flow in the vicinity of the cohesive zone were visually expressed by this model. These results were similar to those of cold model experiments and the burden structure observed in the dissected blast furnace. The influence of the coke rate on the gas flow was also analyzed using the above model. The change in the gas flow under a low coke rate condition could be well recognized.

DOI： 10.2355/isijinternational.52.1010

Language：English   Publishing type：Research paper (scientific journal)  

Wettability of a solid by a liquid plays a key role in achieving the purpose of the process in moving bed-type reactors. In recent years, particle method has been proposed for the design of processes which include multiphase flows. Using this method, it is possible to analyze a free surface flow without explicitly tracking the interface. Although surface tension and wettability models using the particle method have already been proposed, the complexity of calculations of normal line and curvature of the surface particle has been pointed out as a problem. In this study, surface tension and wettability model were introduced in terms of interparticle potential, and theoretical and experimental verifications were performed for a 3-dimensional particle method which stabilizes the internal pressure distribution in fluids. The analytical solution for the droplet oscillation period by this method showed good agreement with the theoretical solution, and the surface tension between a gas and liquid could be calculated correctly. Because the difference in the number density of a liquid phase and solid phase becomes remarkable in a 3-dimensional space, a technique which corrects for this in particles at a three-phase interface was introduced. Time change in the droplet shape was compared with the experimental results by changing the droplet impact velocity to obtain agreement of the Weber number. It is considered possible to express the droplet shape correctly during rotating falling on a solid surface. [doi:10.2320/matertrans.M2011330]

DOI： 10.2320/matertrans.M2011330

Event date： 2023.6

Language：Japanese  

Country：Japan  

Event date： 2023.6

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2023.6

Language：Japanese  

Country：Japan  

Event date： 2023.3

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Language：Japanese  

MPS法によるホールドアップ現象に与える融体物性の影響解析

Language：Japanese  

粒子法シミュレーションを用いた高炉内鉱石の軟化溶融滴下挙動解析

Language：Japanese  

DEM‐CFDモデルによる高反応性コークス使用時の充填層内反応解析

Language：Japanese  

高炉低炭素化を指向した製銑研究の課題と展望

Language：Japanese  

DEM‐CFDによる不均一系充填層内反応解析

Language：Japanese  

DEM‐CFDによる高炉内充填層の動力学シミュレーション

Language：Japanese  

Eulerian‐Lagrangianカップリングによる3次元充填構造を反映した高炉モデル

Language：Japanese  

MPS法による融着帯下部からの液滴下モデルの構築

Language：Japanese  

分散現象を考慮した高炉数式モデルの発展と課題

Language：Japanese  

荷重軟化シミュレーションによるコークス混合装入時の通気性評価