Control of the energy structure of the working space of arc steelmaking and electric ore smelting furnaces—mechanism for increasing their efficiency

The energy processes in the three main zones of the working space of an electric arc furnace, namely, the zone of charge materials and slag with a low electrical conductivity, the arc discharge zone, and the zone with materials having metallic conduction, are considered. It is shown that the distribution of energy fluxes between these zones in electric ore smelting furnaces and electric arc furnaces determines the efficiency of their dc operation. A general approach to creating high-efficiency melting furnaces is proposed. This approach implies control of the structure of energy fluxes; as a result, energy and raw materials are saved and the ecological characteristics of the processes and the metal quality are improved.     

Modeling of fluid flow and heat transfer in the plasma region of the dc electric arc furnace

A mathematical model describing the transport processes in the plasma arc in dc electric arc furnaces has been developed. The equations of conservation of mass, momentum, and energy are solved numerically in conjunction with Maxwell's equations of the electromagnetic field to calculate the velocity and temperature distributions in the plasma region. The heat transfer from the arc to a rigid anode surface is calculated. The model is applied to obtain quantitative results on the relative importance of the various modes of heat transfer from the electric arc to the anode surface. Computational results were obtained for varying arc current magnitudes and anode-cathode distances. The model predicts higher arc jet velocity and a broader arc core at higher arc current. The shorter arc length is more efficient for transferring heat to the anode.     

Acoustic characteristics of electric arc furnaces

A mathematical model is constructed to describe the appearance and development of the noise characteristics of superpower electric arc furnaces. The noise formation is shown to be related to the pulsation of the axial plasma flows in arc discharges because of the electrodynamic pressure oscillations caused by the interaction of the self-magnetic field with the current passing in an arc. The pressure in the arc axis changes at a frequency of 100 Hz at the maximum operating pressure of 66 kPa for an arc current of 80 kA. The main ac arc sound frequencies are multiples of 100 Hz, which is supported in the practice of operation of electric arc furnaces. The sound intensity in the furnace laboratory reaches 160 dB and is decreased to 115–120 dB in the working furnace area due to shielding by the furnace jacket, the molten metal, and the molten slag. The appropriateness of increasing the hermetic sealing of electric furnaces and creating furnaces operating at low currents and high transformer voltages is corroborated.     

Modelling of electrovortex and heat flows in dc arc furnaces with bottom electrode

Abstract

The article is devoted to the investigation of interaction between electrovortex and heat flows of liquid metal in dc arc furnaces with a bottom electrode. A mathematical model of liquid steel flows in a dc arc furnace with a bottom electrode was developed, and an algorithm of a three-stage solution was produced based on standard software packages. The results of electromagnetic, heat transfer and hydrodynamic analysis in industrial dc arc furnaces are given. It is shown that the Lorentz force makes up ～30% of the volumetric gravity force and makes the main contribution to vortex flow of liquid metal in a dc arc furnace. The convection flows with the maximum heat power of furnace make a significant contribution to the vortex flow of liquid metal, and the maximum value of the vortex flow velocity is ～1·5 times more than the movement without convection. The verification of results has been carried out by comparing them with general electrovortex flows theory, experimental data and results of similar software packages.     

Adjusting characteristics of electric arc furnaces

The dependences of the electric and electrotechnological parameters of electric arc furnaces on the arc length in different heat periods are considered.     

直流电弧炉用镁碳质耐火材料的研究

直流电弧炉有利于提高钢质量和减少闪变（电网干扰）故它的应用正在推广，与交流电弧炉相比，安的电极安装在炉子底部，电极的寿命和安全很重要，本文阐述了直流电弧炉用镁碳质耐火材料的研究及发展。     

Effect of electrodynamic phenomena in arc furnaces on the meniscus formation in a liquid metal

The main laws of the electrodynamic action of an electric arc on the surface of the liquid metal bath in electric arc furnaces of various types are considered.     

Thermal operation of the DSP-120 Consteel furnace in the Ashinsk metallurgical works

The heat losses with waste gases in modern electric arc furnaces are 20–25%. Scrap heating by waste gases is performed in Fuchs Systemtechnik shaft furnaces and Consteel furnaces with conveyer charging. The results of balance heats conducted in the DSP-120 Consteel electric furnace located in the Ashinsk metallurgical works are presented, and measures for increasing the energy efficiency of its operation are proposed.     

New trends in the development of dc arc furnaces

New trends in the development of dc arc furnaces, which make it possible to extend their energy and technical capabilities, are considered.     

Universal Electrical Characteristics of Steelmaking Arc Furnaces

A single dependence of the power factor on the arc current is established for all steelmaking arc furnaces. On that basis, universal furnace characteristics may be calculated, determining the functional relationship of the active, reactive, and apparent power with the arc current. By that means, precise and simple calculation of the electrical characteristics is possible for arc furnaces of any power, with any primary and secondary transformer voltages, including superpowerful furnaces with reactors on the step-up side of the transformer. Detailed analysis of all the arc characteristics is consistent with current notions regarding the physical processes in arc furnaces.     

Role of prereduced pellets in the slag foaming in modern EAFs

The problems of electric arc furnace slags are considered, and the role of prereduced pellets in the slag foaming in electric arc furnaces is studied. The optimum rate of loading of prereduced pellets into a furnace that ensures effective steelmaking slag foaming is determined as a function of the degree of pellet prereduction.     

低频供电技术在5MVA矿热炉上的应用

介绍了低频供电技术的原理其应用于铁合金矿热炉的实施办法,并在５ＭＶＡ颃中铁电炉上取得了较好的使用效果。     

Increasing the output and the energy efficiency of electric arc furnaces with shaft heating of metal scrap

It is proposed to equip the electric arc furnaces with shaft heating of scrap that operate with continuous scrap melting in a liquid metal with powerful gas-oxygen burner units. When scrap is heated to 800°C at a gas flow rate of 15.5 m³/t and a bath is blown by oxygen at the slag-metal boundary, fuel-arc steelmaking units can successfully compete with the best modern electric arc furnaces in capacity and have ecological advantages.     

电炉变压器升压扩容技术改造与效益

随着工业生产的发展与操作技术水平的不断提高,对电炉变压器与生产工艺密切配合提出了更高的要求,通过对历年的生产记录资料总结并加以理论分析,提出了电炉为压器技术参数应同生产工艺参数密切配合,以提高产量与经济效益。     

Electrical optimization of superpowerful arc furnaces

Requirements on the systems controlling the electrical conditions of superpowerful arc furnaces in steel smelting are outlined. The basic principles for electrical optimization at different phases of smelting are considered. An improved mathematical model is proposed for analysis of the arc furnace’s electrical characteristics and the dynamics of the automatic control system governing electrode motion. A diagnostic system capable of identifying the phase of smelting on the basis of the harmonics of the arc currents shortens the furnace’s working cycle and reduces the power consumption.     

直流（DC）电弧炉技术的发展动态

大电流可控硅整流电源的发展和炉底电极这一难题的解决促使直流（ＤＣ）电弧炉的迅速发展，近几年大部分新建电弧炉为ＤＣ炉并将一些已有的交流（ＡＣ）电弧炉改成ＤＣ电弧冶炼。     

中小型三相交流硅锰炉电气特性不平衡分析

中小型三相交流矿热炉存在严重的电气参数不平衡问题,导致冶炼过程炉况不稳、功率因数低、电耗高,难以实现冶炼过程三相熔池功率和温度场的平衡控制.以容量为12.5 MVA的三相交流硅锰炉为对象,在对其关键电气参数进行检测与计算的基础上,分析了三相短网不平衡、现有人工操作机制以及炉内变化所致不平衡对三相交流矿热炉电气特性的影响...     

我国电炉钢生产现状及发展前景

我国电炉钢产量逐年上升,2007年已接近5 000万t,同时电弧炉容量趋向大型化,2007年≥50 t电弧炉产能约占电炉钢总产能的83.5%,电耗接近300 kWh/t,冶炼周期≤60 min,平均电极消耗2.43 kg/t,但炉料结构、生产钢种、节能环保等方面的技术开发仍需加大力度,未来我国电弧炉流程仍有很大发展空间。     

Application of the triad of blast furnace,oxygen converter,and electric arc furnace for reducing of carbon footprint

Carbon footprint is the mass of carbon formed in the full cycle of manufacturing one kind or another product. This carbon is included in greenhouse gases. During production of iron and steel are generated carbon monoxide and greenhouse gases: methane, and carbon dioxide. Methane and carbon monoxide burn to carbon dioxide by secondary energy resources. By this means, the carbon footprint by the production of iron and steel has determined by the weight of carbon dioxide formed in this production. As results of analysis of the processes of manufacture of iron and steel, it has revealed that the tandem of blast furnace with electric arc furnace is characterized by a lower value of integrated emissions of CO₂ than the tandem of blast furnace with an oxygen converter. It was proposed to process of the cast iron made by one blast furnace, then in the oxygen converter, and, at last, in one or more electric arc furnaces. Moreover, the electric arc furnace is loaded by 30% of iron produced in blast furnace, and the remaining 70% are complemented by metal scrap. In the oxygen converter is loaded, the part of cast iron (75–85%), that remained after processing in the arc furnace. The converter is applied the metal scrap for full loading. Calculations of total emission of carbon dioxide for different triads of these units are made. Simultaneous use of oxygen converter with electric arc furnaces for cast iron smelting (obtained from one blast furnace) helps to reduce reliably the emission of carbon dioxide to 20% as it is follows from these calculations. This suggests that such a triad of used units conforms to green technology. Example of the use of mentioned triad is for a full load of the converter applied to metal scrap. The calculations total emissions of carbon dioxide for different triads of these units were performed. From these calculations it follows that the simultaneous use of oxygen converters after electric arc furnaces for smelting iron (obtained from one blast furnace), it helps to reduce the emission of carbon dioxide to 20%. This suggests that this triad of used units conforms to green technology. An example of using this triad is in the Magnitogorsk Iron and Steel Works, where along with the oxygen converter, electric arc furnaces with the use of locally produced electricity at burning fuel of secondary energy resources from units, in which the fuel is burnt. This practice can be recommended for a number of other metallurgical enterprises.     

Calculation and Analysis of the Relationship Between the Efficiency and Position of Electric Arcs and Power Consumption in Electric Arc Furnaces (EAF) of Smaller and Larger Capacity. Part I. Calculation and Analysis of the Relationship Between Arc Efficiency and Power Consumption

Metallurgist - The arc efficiency and specific power consumption were calculated and analyzed for the small (1.5 to 20 tons) and large (100 to 120 tons) capacity electric arc furnaces. In the...