Applications of Computational Fluid Dynamics (CFD) in iron- and steelmaking: Part 1

Abstract

All operations in process metallurgy involve complex phenomena comprising momentum, heat, and/or mass transport; iron- and steelmaking is not an exception. Transport phenomena, i.e. fluid flows, heat transfer and mass transfer, play a dominant role in process metallurgy since their respective laws govern the kinetics of the various physical phenomena occurring in ironmaking and in steelmaking. These phenomena include such events as three-phase reactions, entrainment of slag and gas in liquid steel, vacuum degassing, alloy melting and mixing, the movements and flotation of inclusions, melt temperature losses, residence times in a metallurgical reactor, erosion of refractory linings, etc. In all these aspects, the evolution in our techniques and abilities to model single and multiphase flows and their attendant heat and mass transfer processes has contributed significantly to our understanding and effectively operating these processes, to designing improvements, and to developing new processes. To be ignorant of these matters can doom a processing operation to the scrap heap of metallurgical failures. Computational fluid dynamics (CFD) and computational heat and mass transfer has been a very effective tool over the last three decades, for modelling iron- and steelmaking processes, starting from the blast furnace up to continuous casting and beyond. With the advent of commercial CFD packages and ever increasing computational power through parallel processing, CFD has now become the dominant approach for predicting various aspects in iron- and steelmaking processes. In Part 1 of this review paper, the applications of CFD in ironmaking processes are thoroughly reviewed, discussed and critiqued. In Part 2, fluid flows and CFD in steelmaking and steel casting processes are similarly reviewed and critiqued.     

Applications of Computational Fluid Dynamics (CFD) in iron- and steelmaking: Part 2

Abstract

After presenting a review of some applications of computational fluid mechanics (CFD) to ironmaking processes in Part 1, the authors now explore the use and extent of CFD in steelmaking and steel casting processes. Steelmaking processes generally include the basic oxygen furnace, electric arc furnace or equivalent, the ladle and continuous casting and incorporating a tundish and moulds. All these steelmaking processing steps involve highly coupled complex transport phenomena. The use of CFD to model such processes has been an active area of research for the last three decades. Many models have been developed to predict mixing behaviour, slag foaming, gas–liquid interactions, multiphase flows, as well as heat and mass transfer aspects. In the present review, the role of CFD in modelling steelmaking operations is reviewed, discussed and critiqued.     

Improvement of Natural Gas Combustion in the Air Tuyere of a Blast Furnace

Metallurgist - The work analyzes the results of industrial and numerical experiments obtained by various researchers on the application of various methods for ensuring the ignition and subsequent...     

基于AGV技术的侧吹炉自动捅风眼机器人研制

捅打风眼是侧吹熔炼生产工艺的重要操作,目前还没有适用于侧吹炉的自动捅风眼设备。针对侧吹炉特点,基于AGV机器人技术,首创出一种适用于侧吹炉的智能化捅风眼机器人装置,实现了自动导航定位、风眼对准、智能化捅打等功能。该装置已经在工业现场得到应用,彻底解决侧吹熔炼生产中风眼自动化捅打难题。     

Computational Fluid Dynamics Simulation of Supersonic Oxygen Jet Behavior at Steelmaking Temperature

Supersonic oxygen jets are used in steelmaking and other different metal refining processes, and therefore, the behavior of supersonic jets inside a high temperature field is important for understanding these processes. In this study, a computational fluid dynamics (CFD) model was developed to investigate the effect of a high ambient temperature field on supersonic oxygen jet behavior. The results were compared with available experimental data by Sumi et al. and with a jet model proposed by Ito and Muchi. At high ambient temperatures, the density of the ambient fluid is low. Therefore, the mass addition to the jet from the surrounding medium is low, which reduces the growth rate of the turbulent mixing region. As a result, the velocity decreases more slowly, and the potential core length of the jet increases at high ambient temperatures. But CFD simulation of the supersonic jet using the k−ε turbulence model, including compressibility terms, was found to underpredict the potential flow core length at higher ambient temperatures. A modified k-ε turbulence model is presented that modifies the turbulent viscosity in order to reduce the growth rate of turbulent mixing at high ambient temperatures. The results obtained by using the modified turbulence model were found to be in good agreement with the experimental data. The CFD simulation showed that the potential flow core length at steelmaking temperatures (1800 K) is 2.5 times as long as that at room temperature. The simulation results then were used to investigate the effect of ambient temperature on the droplet generation rate using a dimensionless blowing number.     

高炉风口区燃烧状态监测技术研究

介绍了国家“八五”重点攻关课题“氧煤强化炼铁新工艺研究”中开发的高炉风口区燃烧状态监测技术及其应用情况,在富氧喷煤工业试验中的应用证明,所开发的以红外成像的多种图像分析方法和直接测温技术相结合的综合测试分析技术,可以更科学、更全面地了解风口内煤粉燃烧的瞬时状态和燃烧发展过程,为进一步提高燃烧率研究探明方向。     

Computational Fluid Dynamics Modeling of Supersonic Coherent Jets for Electric Arc Furnace Steelmaking Process

Supersonic coherent gas jets are now used widely in electric arc furnace steelmaking and many other industrial applications to increase the gas–liquid mixing, reaction rates, and energy efficiency of the process. However, there has been limited research on the basic physics of supersonic coherent jets. In the present study, computational fluid dynamics (CFD) simulation of the supersonic jet with and without a shrouding flame at room ambient temperature was carried out and validated against experimental data. The numerical results show that the potential core length of the supersonic oxygen and nitrogen jet with shrouding flame is more than four times and three times longer, respectively, than that without flame shrouding, which is in good agreement with the experimental data. The spreading rate of the supersonic jet decreased dramatically with the use of the shrouding flame compared with a conventional supersonic jet. The present CFD model was used to investigate the characteristics of the supersonic coherent oxygen jet at steelmaking conditions of around 1700 K (1427 °C). The potential core length of the supersonic coherent oxygen jet at steelmaking conditions was 1.4 times longer than that at room ambient temperature.     

Study of Flow in a Blanket Clarifier Using Computational Fluid Dynamics

This work simulated the flow pattern of the sludge blanket clarifier at the Bansin Water Treatment Plant, Taiwan by multiphase flow, three-dimensional analysis. The following three models were developed individually: One-phase flow (water) in the clarifier—this model acquires the basic water-flow pattern; a homogeneous porous medium at the bottom of the clarifier—this porous medium represents the sludge blanket; and, the Eulerian granular multiphase model, which was utilized to obtain solid effluent flux and to determine the effects of particle size and density on sludge blanket stability. Analytical results indicated that the clarifier has two principal circulations inside and outside the reaction well. A plentiful, dense and thick sludge blanket should exist at the clarifier bottom; otherwise particles could flow out through the gap between bottom of the reaction well and top of blanket surface, resulting in poor water quality. In the multiphase flow model, large particles and a high particle density are positively correlated with sludge blanket stability.     

Validation of a Three-Dimensional Computational Fluid Dynamics Model of a Contact Tank

A three-dimensional (3D) computational fluid dynamics (CFD) model of a contact tank is presented in this paper. The model results are compared against 3D velocities and flow through curve (FTC) data, representing a tracer concentration profile, from a 1:8 scale physical model. The objective is to demonstrate that CFD models can simulate both the FTC and the 3D velocity field quite well. Simultaneous validation of velocities and FTC is important in ascertaining the predictive capabilities of CFD models, as physical model studies indicate that different baffle arrangements can lead to similar FTCs. Therefore, a good prediction of only FTC, as presented in previous 3D CFD model studies, does not necessarily imply a correct simulation of the flow field.     

Experimental Validation of a Computational Fluid Dynamics Model of Copper Electrowinning

The hydrodynamics that occur in the space between the electrode plates in copper electrowinning (EW) are simulated using a computational fluid dynamics model (CFD). The model solves for the phases of gas oxygen bubbles and electrolyte using the Navier–Stokes equations in a CFD framework. An oxygen source is added to the anode, which sets up a recirculation pattern. The gradients in copper near the cathode lead to buoyancy forces, which result in an uplift in the electrolyte close to the cathode. This study investigates the experimental validation of the CFD model using a small/medium-scale real EW system. The predicted fluid velocity profiles are compared with the experimental values, which have been measured along various cross sections of the gap between the anode and the cathode. The results show that the CFD model accurately predicts the velocity profile at several heights in the plate pair. The CFD model prediction of the gas hold-up and the recirculation pattern is compared with visualizations from the experiment. The CFD model prediction is shown to be good across several different operating conditions and geometries, showing that the fundamental underlying equations used in the CFD model transfer to these cases without adjusting the model parameters.     

A Mathematical Model of a Blast Furnace Injection Tuyere

One way to further utilise produced gases in an integrated metallurgical plant is to replace oil with gas as a reducing agent in a modern blast furnace. Accordingly, it is of great interest to study the injection of reducing gas into the blast furnace. Therefore, a three‐dimensional mathematical model has been developed which simulates the injection of the gas by lances into the tuyere. The model includes the coupled solution of the flow field and the chemical reaction of the gases in the tuyere. Two different types of fuel gas, coke oven gas (COG) and basic oxygen furnace gas (BOF) have been modelled using one injection lance. The modelling technique is presented and discussed as well as the implied results. Furthermore, process parameters such as different gas compositions etc. are investigated using the developed model. Not surprisingly, the main results show that the COG is combusted more completely than BOF gas, which leads to higher flame temperature of the blast putting demand forward to lower the heat load of the tuyere. However, the modelling of the raceway is as far not included in the model, hence the influence of the outlet boundary condition at the tuyere is not reflected in the presented results.     

Modelling of Industrial Processes Using Computational Fluid Dynamics

Abstract

Some examples of computational fluid dynamics in modelling and optimization of industrial processes are discussed. Examples include film cooling of turbine blades, gallium arsenide crystal growth, and black liquor recovery boilers. Modelling aspects and numerical techniques used are discussed together with some limitations and possible remedies. © 1998 Canadian Institute of Mining and Metallurgy. Published by Elsevier Science Ltd. All rights reserved.

Résumé

On discut de quelques exemples de calcul par ordinateur de la dynamique des fluides, dans la modélisation et l'optimisation de procédés industriels. Les exemples incluent le refroidissement pelliculaire d'aubes de turbine, la croissance de cristal d'arséniure de gallium et les fours de récupération de liqueur noire. On discute des aspects de la modélisation et des techniques numériques utilisées ainsi que de certaines limitations et de remèdes possibles. © 1998 Canadian Institute of Mining and Metallurgy. Published by Elsevier Science Ltd. All rights reserved.     

酒钢高炉风口破损治理实践

对酒钢高炉风口破损原因进行了分析,通过采取提高渣铁水物理热、控制碱负荷、控制煤比等措施,风口破损得到了有效治理。     

Computational Fluid Dynamics Study of a Noncontact Handling Device Using Air-Swirling Flow

The vortex gripper is a recently developed pneumatic noncontact handling device that takes advantage of air-swirling flow to cause upward lifting force and that thereby can pick up and hold a work piece placed underneath without any contact. It is applicable where, e.g., in the semiconductor wafer manufacturing process, contact should be avoided during handling and moving in order to minimize damage to a work piece. For the purpose of a full understanding of the mechanism of the vortex gripper, a computational fluid dynamics (CFD) study was conducted in this paper, and at the same time, experimental work was carried out to measure the pressure distribution on the upper surface of the work piece. First, three turbulence models were used for simulation and verified by comparison with the experimental pressure distribution. It is known that the Reynolds stress transport model (RSTM) can reproduce the real distribution better. Then, on the basis of the experimental and numerical result of RSTM, an insight into the vortex gripper and its flow phenomena, including flow structure, spatial velocity, and pressure distributions, and an investigation into the influence of clearance variation was given.     

Experimental Investigation and Computational Fluid Dynamics Simulation of the Magnetite Concentrate Reduction Using Methane-Oxygen Flame in a Laboratory Flash Reactor

Metallurgical and Materials Transactions B - An experimental investigation of the reduction of magnetite concentrate particles was conducted in a laboratory-scale flash reactor representing a novel...     

基于CFD模拟的蓄热式加热炉燃烧优化研究

当前蓄热式加热炉普遍存在的火焰刚性偏弱及火焰不稳定等特点,为了优化加热炉的燃烧工况,文章通过仿真软件对蓄热式加热炉进行网格划分建立模型,充分对炉内燃烧状况进行分析研究,从而得出蓄热式加热炉的最优化参数。     

Hot-Metal Desulfurization Using Calcium Carbide and Calcium Oxide in Transfer Ladle: A Computational Fluid Dynamics Investigation

In this study, a 3D transient computational fluid dynamics (CFDs) model that simulates hot-metal desulfurization (HMD) using calcium carbide and calcium oxide in an experimental-scale ladle with a 70 kg capacity is presented. The model takes into account the efficiency of reagent-particles-penetrating carrier gas bubbles and is validated through experimental work, with an average difference of 7.06%. In this research, the effects of varying reagent particle sizes, hot-metal temperatures, gas flow rates, and ladle design on desulfurization rates are discussed. The results indicate that when particle diameter decreases from 30 to 20.9 and 11.8 μm, desulfurization rates rise from 50.92% to 66.02% and 89.99%, respectively. Regarding hot-metal temperature, a 100° range results in a final desulfurization rate difference of less than 3%. This study also reveals that increasing the carrier gas flow rate from 13 to 15 SLPM reduces the removal rate by 6.10%. As particle gas flow rate increases from 200 to 300 g min⁻¹, the removal rate increases by 9.02%. In the lance arrangement analysis, the duo lance system demonstrates nearly identical desulfurization performance to the single-center lance system, which outperforms the off-center lance system.     

Fluid Flow and Heat Transfer Modeling of AC Arc in Ferrosilicon Submerged Arc Furnace

 arc has been developed and used to predict heat transfer from the arc to the molten bath in ferrosilicon AC submerged-arc furnace. In this model the time-dependent conservation equations for mass, momentum and energy in the specified domain of plasma zone have been solved numerically coupled with the Maxwell and Laplace equations for magnetic filed and electric potential respectively. A control volume based finite difference method was used to solve the governing equations in cylindrical coordinates. The reliability of the developed model was tested by comparison with the data available in the literature. The present model showed a better consistency with the data given in the literature because of solving the Maxwell and Laplace equations simultaneously for calculation of current density. Parametric studies were carried out to evaluate the effect of electrical current and arc length on flow field and temperature distribution within the arc. According to computed results, a lower power input lead to the higher arc efficiency.