炼钢电弧炉加热工艺的革新

介绍了炼钢电弧炉炉料预热的重要性和加大留钢量的优越性。在大留钢量的钢水中熔化废钢炉料会形成纯平熔池操作,这种操作方式能降低电压闪变和提高热效率。固体废钢炉料和钢水之间的热交换是靠炉底吹氩搅拌来改善的。最后,给出了不同加热方式的加热效果。     

佛罗里达钢厂的Consteel技术

Consteel生产线由连续加料系统、预加热装置及电弧熔化精炼炉等组成。预加热装置主要利用电炉废气中的余热,使废钢料加热到约500℃,熔化电耗仅为380kW·h/t,从而可节约熔化废钢的能耗20%～40%。连续吹氧使耐火材料损耗降到最低限度,使电弧炉能     

炼钢电弧炉工艺过程的动态模拟

基于物料平衡和热平衡以及化学反应的热、动力学，结合相关的参数建立了电弧炉冶炼过程的动态模型。该模型可动态地模拟电弧炉冶炼过程中的废钢量、炉温、渣量、钢液成分、炉渣组成的炉气成分的变化。文中以某100t交流电弧炉冶炼的操作参数为例进行了仿真计算，并与现场数据作了对比。结果表明模型可与实际结果吻合得很好。完善后的模型可望对生产全过程作出动态的预报，并可综合评估电弧炉冶炼的能耗、物耗、生产效率等技术经济指标，从而为电弧炉工艺改进、生产操作与控制提供指导。     

氧燃料喷吹工艺效果显著

目前,在电弧炉炼钢过程中,氧—燃料烧嘴的采用是一种不容忽视的趋势。今天在日本至少有80％的电弧炉安装了氧—燃料烧嘴,欧洲大约有30％,不过美国则刚刚开始。 瑞典的斯梅德耶巴肯轧钢公司在熔炼废钢的120吨电弧炉上安装了三只AGA—MF700氧—燃料烧嘴。该电弧炉自1979年以来的连续操作结果表明,氧燃料烧嘴系统可以使熔化速率提高20％。在正常操作条件下,70千瓦·时/吨的氧—燃料可以增加产量15％;每吨钢的石墨电极消耗降低1磅;耐火材料消耗保持不变。     

WZ003059 电弧炉炼钢新工艺的开发——《电气制钢》

为降低炼钢成本，日本大同特殊钢公司推出了利用夜间廉价电力进行熔化并倒人大型保温炉内存储，白天再倒入装有废钢炉料的电弧炉内进行熔化精炼的炼钢新工艺。简述了上述炼钢新工艺的概要。     

电弧炉废钢预热技术发展

从节能减排重要性出发,阐述电弧炉废钢预热技术,简要分析国外典型废钢预热电弧炉技术发展及优劣,重点介绍中冶赛迪自主研发的CISDI-GreenEAF、CISDI-AutoARC废钢预热电弧炉及其关键技术。     

圆形铝熔炼炉内非稳态热工过程数值模拟

针对铝熔铸过程中常用的圆形铝熔炼炉,利用FLUENT软件,根据能量守恒方程、动量方程建立铝熔炼炉内热工过程数学模型,采用标准k-ε湍流模型、P-1辐射模型对铝熔炼炉内非稳态传热及流动过程进行数值模拟研究。考虑到铝料熔化过程会消耗一部分能量,采用等效比热法将铝料的熔化潜热转换为相应的比热值进行计算。通过数值模拟得到了炉内流场、炉膛及铝料温度场分布情况。模拟结果与实际情况相符,为铝熔炼炉的设计与优化研究提供了理论依据。     

一种余热利用相变石蜡储热过程的数值模拟

基于一种相变储热石蜡,考虑熔化过程中液相的自然对流情况,建立了矩形腔内石蜡熔化过程的数学模型,并利用该模型进行了数值模拟,分析了石蜡熔化过程中的温度场变化、流场变化、相界面移动情况。通过采用铝制翅片的方式强化传热,并分析了翅片位置对该石蜡熔化时间的影响。模拟结果表明,在y=0.1、y=5、y=10、y=15mm时,与不采用翅片相比,储热时间分别缩短了43.1%、52.0%、38.3%、22.2%。研究结果对相变储热器的优化设计有一定意义。     

中国电弧炉发展现状及趋势

阐述了中国电弧炉发展的现状,分析了炼钢技术的发展趋势及制约我国电弧炉发展的因素。在此基础上介绍了电弧炉炼钢的原料、能源状况,指出未来我国废钢供应量和电能富余量将增加,有利于发展电弧炉炼钢流程。同时分析了新型电弧炉的使用情况,指出了电弧炉炼钢技术的发展趋势。     

直流电弧炉水冷钢棒式底电极传热过程的数值仿真

采用文献[1]建立的“直流电弧炉水冷钢棒式底电极传热过程二维数学模型”，在验证模型正确可信的基础上，对直流电弧炉底电极的传热过程进行了数值仿真计算，所得结论对直流电弧炉的生产有重要的指导意义。     

Numerical Study of Melting of Scrap Metal

A one-dimensional time-dependent heat transfer model is presented for the melting process in a circular scrap melter. The phase change problem is tackled using an enthalpy-based method, and the complex scrap geometry is described with the porosity concept, i.e., the blocking effect of the scrap is represented by a blocking factor that is a function of the scrap porosity. Flame length is represented by a flame damping factor. The numerical procedure is carried out in three stages, from initial heating to complete melting. Some typical cases are simulated. Results show that the flame damping factor can significantly influence the melting process. A lower damping factor gives better uniformity in metal temperature distribution. The melting time can be improved drastically by decreasing this factor. The convective heat transfer coefficient dominates the temperature profile. The higher the convective heat transfer, the faster the temperature increase in the lower part of the furnace. A long flame and good stirring of the melt enhance the melting process.     

油氧火焰熔化废钢数学模型的研究

在油氧火焰熔化棒体实验基础上,通过建立数学模型,与实验进行对比研究,结果表明：实验结果与熔化数学模型计算棒体的熔化速度相符合。     

Improvement of electrical arc furnace operation with an appropriate model

Electrical arc furnaces are commonly employed in industry to produce molten steel by melting iron and scrap steel. Furnace control is a necessary operation for production optimization. The principal parameters to be controlled are: maximum productivity requirements, minimum power off time, good power quality and safety. The aim of this study is to achieve all these objectives. Hence, because of the stochastic and dynamic behaviour of the arc during the melting process, a proposed model is checked with measurements at an industrial electrical arc furnace. How electrodes position and transformer taps can affect X and R arc function are discussed in detail. This new operating strategy has been determined taking into account Flicker, melting stages and electrode positions. It is shown that optimum efficiency can be reached by the integration of the proposed model in regulation loop.     

Influence of direct reduced iron on the energy balance of the electric arc furnace in steel industry

A model of the EAF energy efficiency was developed based on a closed mass and energy balance of the EAF melting process. This model was applied to industrial EAFs in steel industry charged with scrap or with mixes of scrap and DRI. Complex mass and energy conversion in the EAF was simplified with the introduction of mass and energy conversion efficiencies for the conversion of oxygen and the energy conversion of electrical energy in the electric arcs, chemical energy from the oxidation reactions in the melt and energy from the combustion of burner gas. It turned out that close agreement with observed process parameters from 16 EAFs is obtained by slight variations of the efficiency values. Especially the sensitivity of the steel temperature from the energy conversion efficiency of the electric arc energy indicates the importance of efficient foaming slag operation in EAF steel making. Characteristics and process parameters of DRI charged EAFs are discussed. Model results for a series of case studies illustrate the correlations between DRI chemical composition, DRI portion, oxygen consumption, etc. with electrical energy demand in order to indentify cost-effective EAF process conditions.     

Numerical Study of Convection Melting Inside Ice Storage Systems by the Lattice Boltzmann Model

Abstract

The internal melt ice-on-coil tank with horizontal pipes is widely used in ice storage systems. The tank’s discharge process is greatly affected by the natural convection process that is caused by melting of the phase change material outside the pipes. To achieve an optimal arrangement of the pipes, a double-population lattice Boltzmann model was developed to simulate the transient solid-liquid phase change behavior in a section of an internal-melt ice-on-coil thermal storage tank with nine aligned built-in horizontal pipes. The evolutions in the phase change interface and melting rate was illustrated with different pipe shapes and pipe connections. Based on the melting rate, the whole melting process was divided into three stages: sharp decrease stage, continuous decrease stage, and snail-melting stage. The numerical results showed that a high melting rate was obtained by preferentially assigning the high-temperature pipes to the upper part of the tank, while a stable melting rate could be obtained when high-temperature pipes were preferentially assigned to the bottom part of the tank.     

One—Dimensional Analysis of Melting in an External Artery Heat Pipe

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Experimental investigation on melting characteristics of ethanolamine–water binary mixture used as PCM

An experimental investigation of the melting process of ethanolamine–water binary mixture used as PCM (phase change material) in a rectangular enclosure with a heated vertical wall is reported in this work. The liquid–solid interfaces were captured and the instantaneous liquid fraction was presented. The effect of natural convection was studied in terms of the molten fraction and the shape of the solid–liquid interface. The correlations of molten fraction and time-averaged Nusselt number are obtained so that the time of the melting process can be predicted. The results indicate that natural convection enhances the rate of melting compared with the pure conduction model and that pure conduction mechanism only occurs at the initial stage of melting. Conduction–convection coupled model is necessary for predicting melting process exactly.     

Determination of equilibrium wire-feed-speeds for stable gas metal arc welding

In gas metal arc welding (GMAW), a consumable electrode wire is fed normally at a pre-determined constant speed in order to achieve a stable welding process for given welding conditions. In this article, a comprehensive mathematical model for GMAW was employed to study the interplay among electrode melting; the formation, detachment, and transfer of droplets; and the plasma arc under various welding conditions. It is found that a stable GMAW process can be obtained through a balance between the wire-feed-speed (WFS) and the dynamic electrode melting rate due to the transient behavior of plasma arc. Otherwise, an unstable welding process including electrode burned-back or stick-onto the weld pool could occur. The model-predicted equilibrium WFS varying with welding current and feeding-wire diameter is in good agreement with the published empirical results obtained through a trial-and-error procedure.     

Modeling snow melting on heated pavement surfaces. Part II: Experimental validation

This paper describes an experimental validation exercise for a newly developed numerical model of the snow melting process on heated pavement surfaces. The model is able to predict the conditions of the snow, ice and water during the snow melting process on hydronically-heated pavements given time-varying weather and heating system boundary conditions. Validation results show that the model satisfactorily predicts the surface temperature and conditions, the degree of snow cover over the heated surface, and outlet fluid temperature given the weather data, inlet fluid temperature, and the fluid mass flow rate. It can therefore be used to analyze the performance of hydronic snow melting systems and can be used in the system design process. Development of the model is described in a companion paper.