Mass Balance Modeling for Electric Arc Furnace and Ladle Furnace System in Steelmaking Facility in Turkey

In the electric arc furnace （EAF） steel production processes, scrap steel is principally used as a raw material instead of iron ore. In the steelmaking process with EAF, scrap is first melted in the furnace and then the desired chemical composition of the steel can be obtained in a special furnace such as ladle furnace （LF）. This kind of furnace process is used for the secondary refining of alloy steel. LF furnace offers strong heating fluxes and enables precise temperature control, thereby allowing for the addition of desired amounts of various alloying elements. It also provides outstanding desulfurization at high-temperature treatment by reducing molten steel fluxes and removing deoxidation products. Elemental analysis with mass balance modeling is important to know the precise amount of required alloys for the LF input with respect to scrap composition. In present study, chemical reactions with mass conservation law in EAF and LF were modeled altogether as a whole system and chemical compositions of the final steel alloy output can be obtained precisely according to different scrap compositions, alloying elements ratios, and other input amounts. Besides, it was found that the mass efficiency for iron element in the system is 95.93%. These efficiencies are calculated for all input elements as 8. 45% for C, 30.31% for Si, 46.36% for Mn, 30.64% for P, 41.96% for S, and 69.79% for Cr, etc. These efficiencies provide valuable ideas about the amount of the input materials that are vanished or combusted for 100 kg of each of the input materials in the EAF and LF system.

Scheduling optimization problem considering time-of-use tariffs and piece-rate machine maintenance in EAF steelmaking

An operating schedule of the parallel electric arc furnaces(EAFs)considering both productivity and energy related criteria is investigated.A mathematical model is established to minimize the total completion time and the total electricity cost.This problem is proved to be an NP-hard problem,and an effective solution algorithm,longest processing time-genetic(LPT-gene)algorithm,is proposed.The impacts of varied processing energy consumption and electricity price on the optimal schedules are analyzed.The integrated influence of the different weight values and the variation between the peak price and the trough price on the optimal solution is studied.Computational experiments illustrate that considering the energy consumption costs in production has little influence on makespan;the computational performance of the proposed longest processing time-genetic algorithm is better than the genetic algorithm(GA)in the issue to be studied;considerable reductions in the energy consumption costs can be achieved by avoiding producing during high-energy price periods and reducing the machining energy consumption difference.The results can be a guidance for managers to improve productivity and to save energy costs under the time-of-use tariffs.

Optimization of power input diagram of 50 t UHP-EAF

In order to improve operation for shortening tap to tap time and saving electrical energy, on the base of no-linear reactance model, the electrical characteristics of the 50 t UHP-EAF in Fushun Special Steel Co. Ltd. were analyzed. Considering steelmaking process conditions, the optimum power-input diagrams were investigated, which can save energy, lower consumption, and raise productivity. This has been verified by production contrast tests. Application of the optimum curve in 50 t UHP-EAF indicates that research method is correct, the 50 t UHP-EAF runs smoothly with lowering electrical energy by 29.35 kW.h/t and shortening power on time by 3 min. The general steps of making optimum power-input specification is also given.

Optimization of power input diagram of 50 t UHP-EAF

In order to improve operation for shortening tap to tap time and savingelectrical energy, on the base of no-linear reactance model, the electrical characteristics of the50 t UHP-EAF in Fushun Special Steel Co. Ltd. were analyzed. Considering steelmaking processconditions, the optimum power-input diagrams were investigated, which can save energy, lowerconsumption, and raise productivity. This has been verified by production contrast tests.Application of the optimum curve in 50 t UHP-EAF indicates that research method is correct, the 50 tUHP-EAF runs smoothly with lowering electrical energy by 29.35 kW-h/t and shortening power on timeby 3 min. The general steps of making optimum power-input specification is also given.

Flexible Power Supply System of AC Electric Arc Furnace

The AC electric arc furnace(EAF)is becoming a core apparatus of the modern steel industry.Nevertheless,it used to be a major threat of power quality in the traditional power supply system.In this paper,a flexible power supply system of the AC EAF is proposed,which is expected to completely alter its inherent cognition of impact load in the power grid.The basics of the power supply for EAF are first reviewed and the novel techniques to enhance the operation flexibility of EAF are introduced.The power circuit and the control structure are then presented,followed by the detailed strategies of various operations fully considering the features of EAF.A large disturbance stability criterion based on the mixed potential theory is also established for the practical application.Both electromagnetic transient simulations using PSCAD and benefit analyses verify the feasibility of the proposed system.

Zinc leaching from electric arc furnace dust in alkaline medium

Physical and chemical properties of electric arc furnace （EAF） dust from Tianjin seamless Pipe Company were measured and analyzed. The zinc leaching tests in alkaline medium were carried out under variation of leaching agent concentration, leaching temperature, leaching cumulative time and solid-to-liquid ratio. The thermodynamics and kinetics of the zinc leaching process were also analyzed. The results show that the EAF dust contains 10% （mass fraction） zinc and the median particle size is 0.69 μm. The zinc recovery of 73.4% is obtained tinder the condition of 90 ℃, 6 mol/L NaOH, and 60 min leaching time. With the increase of concentration of NaOH and the cumulative time, zinc leaching will be significantly increased. The kinetics study demonstrates that the leaching reaction is chemically controlled and the reaction activation energy is 15.73 kJ/mol.

Heat Transfer Analysis for Industrial AC Electric Arc Furnace

The heat transfer analysis was performed for an AC electric arc furnace (EAF). Heat losses by conduction, convection and radiation from outer surface, roof, bottom and electrodes of EAF were determined in detail. Some suggestions about decreasing heat losses were presented.

Application of Extended Kalman Filter to the Modeling of Electric Arc Furnace for Power Quality Issues

Electric arc furnaces(EAFs)represent one of the most disturbing loads in the subtransmission or transmission electric power systems.Therefore,it is necessary to build a practical model to descript the behavior of EAF in the simulation of power system for power quality issues.This paper deals with the modeling of EAF based on the combination of extended Kalman filter to identify the parameter of arc current and the power balance equation to obtain the dynamic,multi-valued u-i characteristics of EAF load.The whole EAF systems are simulated by means of power system blockset in Matlab to validate the proposed EAF model.This model can also be used to assess the impact of the new plant or highly varying nonlinear loads that exhibit chaos in power systems.

EAF steelmaking process with increasing hot metal charging ratio and improving slagging regime

A new electric arc furnace （EAF） steelmaking process with increasing hot metal charging ratio and improving slagging regime simultaneously was developed and applied in a 50 t electric arc furnace for more than a year at No. 1 Steelmaking Plant of Shanxi Taigang Stainless Corporation Limited. The essential fact of the new EAF steelmaking process was to charge hot metal in two portions or steps： firstly, 35wt%-40wt% hot metal was pretreated by blowing oxygen in a specially designed reactor for decar burization and improving hot metal temperature and melting premelted slag; secondly, 30wt% hot metal was charged into EAF with high basicity refining slags from ladle furnace （LF）-vacuum degassing furnace （VD） refining process. The results show that the hot metal charging ratio can reach to about 65wt%-70wt% for the new EAF steelrnaking process; meanwhile, the tap-to-tap time of a 50 t EAF can shorten by 5-10 min, the electricity consumption can decrease by 35-50 kW·h/t, the lime consumption can reduce by 10.5 kg/t of molten steel, and the content of harmful heavy metals in molten steel can be easily controlled to less than the upper limits of aimed steel specification or grade compared with the traditional EAF steelmaking process. In addition, the dephosphorization ability shows a slight strengthening, however, a small degree of lessening for desulphurization ability is observed for the new EAF steelmaking process, but the weakness of desulphurization ability cannot become an obstacle to its further application since a stronger desulphurization ability can be achieved during secondary refining of LF coupled with VD after EAF steelmaking process.

Revamping design of an EAF automatic temperature measurement and sampling robot

The function,features,and architecture of a robot that performs automatic temperature measurement and sampling applied on a 150-t AC electric arc furnace(EAF)production line of Baosteel were presented,and the key points of design and revamping experience on the site layout,device protection,lance tool,probe container,measuring position control,and system safety were summarized.Furthermore,a valuable reference for the application of automatic temperature measuring and sampling robots in EAF steelmaking plants will be provided.

14Mn5Nb无缝钢管“鱼鳞”形外折分析与控制

某厂14Mn5Nb连铸圆坯(Φ330 mm)轧制成无缝钢管(Φ323.8 mm×8.3 mm)后表面出现大量“鱼鳞”状外折缺陷,影响成材率,成为亟须解决的问题。采用缺陷金相分析,“刻槽”试验,铸坯酸洗确定钢管表面“鱼鳞状”缺陷是由连铸圆坯表面横裂纹造成。采用扫描电镜检测,钢种热溯性分析以及现场数据统计,确定铸坯表面横裂纹产生原因为:Φ330 mm圆坯在当前工艺参数下铸坯进拉矫温度在900~950℃,处于第III脆性区转变温度940℃附近;表面存在较多Nb(C、N)析出物,增加了钢种的裂纹敏感性。通过调整钢种Ti含量至0.02%~0.03%,保护渣碱度由0.97提高至1.14,降低结晶器水量,调整二冷水量配比以确保进拉矫温度≥970℃等措施,有效避免了铸坯横裂纹和无缝钢管鱼鳞外折的产生。

3t电弧炉炉膛扩容改造的实践

作者针对公司老龄3 t电弧炉冶炼钢水吨位小、单耗高的实际情况,通过对炉壳出钢口进行适度的改造,进而实现了炉膛的扩容和炉料的扩装,并通过加长出钢槽、增大出钢槽倾角措施,解决了由于出钢口提高而带来的钢水包吊车钢丝绳与电弧炉电极架相互碰撞问题,炉膛扩容改造后从原额定容量3 t扩容到了5 t,显著地提高了钢水冶炼效率,为老龄3 t电弧炉冶炼钢水节能降耗、增产增效提供了技术保障。

电弧钢厂烟气余热回收用三段流化床反应器设计

针对间歇式电弧炉炼钢开盖时因高温烟气散发而导致的热量损失现象,设计了一台组合式流化床反应器。热回收工艺为:以熟石灰粉(Ca(OH)_(2))为介质,在夹带流反应器中,吸收高温(>600℃)烟气中的热量,转化生成CaO,再将CaO置于流化床反应器中进行水化反应,重新生成Ca(OH)_(2)并放热和降温,用于加热锅炉凝汽器循环水的热电循环。参与热回收的熟石灰循环利用。针对CaO降温与反应的温度要求,流化床反应器由高温段、反应段及低温段三段组成。过热的CaO粉末由上至下依次通过各层流化床层。设计包括流化床各段传热工艺计算、机械结构设计及附件选型。三段流化床为整体结构,工艺性好,为间歇余热利用设备制造设计提供借鉴和参考。

大容量直流电弧炉接入对电网谐波的影响分析

大容量直流电弧炉是高功率的非线性负荷,运行时会产生大量谐波,影响电网的电能质量。基于某钢铁集团130t直流电弧炉配电网架构及参数,建立了含治理装置的大容量直流电弧炉的动态仿真模型,分析了大容量直流电弧炉的谐波发射特性及其影响因素。通过现场实测和仿真结果,分析了大容量直流电弧炉接入电网后的谐波特性,验证了静止无功补偿器(SVC)的滤波效果,为直流电弧炉接入电网后的监督和治理提供了参考。

EAF Quantum-新型电弧炉炼钢技术

概述了EAF Quantum电弧炉的最新发展和设计概况。Quantum电弧炉提高了自动化水平,在原料使用、废钢操作、运行和维修等方面进一步增大了灵活性和可靠性,降低了电能成本,在污染物排放和噪声治理方面具有较大优势。通过与现代连铸和轧制技术相结合,EAF Quantum电弧炉是长材和带钢短流程生产的理想选择。

Simulation and analysis of O_(2)-CaO jet behavior with different shrouding fuel mediums in electric arc furnace steelmaking

The O_(2)-CaO jet with shrouding combustion flame demonstrates some advantages in quick melting and effective slag foaming by delivering lime powder deeply into the molten bath.Combining the discrete particle model and the eddy dissipation concept model with the detailed chemical kinetic mechanisms(GRI-Mech 3.0),computational fluid dynamics models of the O_(2)-CaO jet with different shrouding fuel mediums injection were developed.Firstly,the results of the numerical simulation were validated by the measured data of cold test for O_(2)-CaO injection.Then,the interaction between the particles and the gas jet of the O_(2)-CaO jet and the effect of shrouding fuel medium species on the fluid flow characteristics of the O_(2)-CaO jet were analyzed.Results show that the CaO particles can be effectively heated by the shrouding high-temperature combustion flame and compared with the O_(2)-CaO jet without shrouding gas,the potential core length was increased about 2.5,3.3 and 4.3 times by the shrouding flame generated from CO,CH_(4) and C_(3)H_(8).And with shrouding CH_(4) and C_(3)H_(8) injection,the CaO particles can be clustered together in a long distance,which would be helpful to improve the utilization efficiency of CaO particles.

电炉铁水比对供氧量及其利用系数的影响研究

在高铁水比电炉生产过程中,铁水比是影响电炉供氧量及其利用系数的重要因素。本研究结合理论分析和现场数据分析,发现在终点碳含量在0.049%~0.1%,氧气消耗量及其利用系数与铁水比具有较好的线性关系,对高铁水比电炉冶炼制定供氧制度具有一定的借鉴意义。

直流电弧炉无功超短期滚动预测及控制

为提升直流电弧炉系统SVC装置动态补偿性能,提出了一种直流电弧炉无功超短期滚动预测及控制方法。首先,分析并揭示了直流电弧炉的控制原理及无功特性;其次,建立了直流电弧炉超短期无功滚动预测模型,基于AIC信息准则和历史冶炼数据实现了预测模型的定阶;然后,基于预测模型提出了直流电弧炉无功超短期滚动预测控制方法;最后,对预测及控制效果进行了仿真验证。与传统控制方法相比,采用预测控制算法后,瞬时闪变降低了31.16%。所提预测控制算法对直流电弧炉系统SVC装置的闪变抑制效果改善显著。

电弧炉采用直接还原铁炼钢工艺技术分析

分析了直接还原铁作为废钢替代品进行电弧炉炼钢的工艺技术特征,并阐明了影响冶炼电耗的主要因素。结果表明,熔池较大留钢量(≥40%)和诸如强化供氧、底吹和电磁搅拌的强化搅拌始终是促进熔化和缩短冶炼周期(可缩短8%~10%)的重要手段。直接还原铁比例超过30%宜采用连续加料,冶炼前期和中期加料速度一般等于熔化速度28~33 kg/min(供电功率1 MW),需匹配石灰和白云石以防渣线侵蚀,冶炼全程应喷碳使泡沫渣埋弧操作以保证供电效率。为降低冶炼电耗,应控制w[C]1%~4.5%、金属化率≥90%、w[SiO_(2)]≤6%、w[P]≤0.1%、w[S]≤0.04%,使用高C、高金属化率、低SiO_(2)、低P、低S和较高温度的热直接还原铁。采用直接还原铁竖炉和电弧炉相结合的紧凑短流程工艺是低碳节能和洁净化生产的重要方向。

电弧炉炼钢绿色化生产技术研究进展

短流程电弧炉炼钢在节能、环保及生产效率方面优势明显。随着我国环保意识的增强及废钢供给量的不断增加,电弧炉炼钢技术得到快速发展,绿色化生产将成为未来电弧炉炼钢发展的主要方向。电弧炉绿色化生产的核心在于如何降低不可再生能源的消耗,减少环境污染以及提升资源循环利用效率。大量研究表明,废钢破碎分选技术、焦炭替代技术、二噁英治理技术、废钢预热-连续加料技术及余热回收技术在实现电弧炉绿色化生产方面效果显著。文中阐述5种具有代表性的电弧炉绿色化生产技术发展概况,重点介绍其特点及应用效果,同时,对未来电弧炉绿色化生产进行了展望。