直流电弧炉技术浅议

叙述了直流电弧炉的电源，石墨阴极、炉底电极，以及冶炼过程中废钢的熔化、钢液的运动、电弧的特性等，并对直流电弧炉的发展提出了看法。     

直流电弧炉钢棒式底电极热状态数值模拟

 采用Fluent软件和文献建立的二维传热模型,对底电极稳态和非稳态的传热过程进行了数值模拟。计算中考虑了底电极物性随温度的变化、空气隙的等效对流换热系数、底电极内部电磁力和焦耳热的影响等,并采用UDF函数加以实现。通过数值模拟,研究不同底电极结构、电流强度以及绝热/绝缘材料熔损对底电极热状态的影响。计算得到的冷却水进出口温差随冶炼时间的变化与现场实测结果吻合,进一步验证了所建模型和参数选择的合理性。计算结果表明,底电极周围绝热/绝缘材料熔损和电磁力对底电极的热状态和熔化深度起着重要的作用。     

直流电弧炉技术的开发

本文论述直流电弧炉技术开发。直流电弧炉有节约电极消耗、降低能耗、减轻电压闪烁等优点；直流电弧炉的关键设备是炉底电极，马来西亚ＡＢＢ直流电弧炉的可导电炉底底电极寿命超过１０００炉次，而法国ＳＭＥ直流电弧炉的水冷炉底底电极寿命超过１３００炉次。     

直流矿热炉熔炼硅锰合金温度场-电磁场数值模拟

采用直流供电成为电弧炉熔炼硅锰合金的发展方向.由于直流供热强度增加,炉衬的温度分布及传热规律需要重新考察及设计.建立了炉衬与炉内熔池耦合的三维非稳态传热模型,研究给定不同外加电压时直流矿热炉炉内的温度场和电磁场.研究表明,外加电压由100 V增大到300 V后,电弧区的最高温度增大了 150％.底电极中心与炉壁的温差T...     

直流电弧炉的特性,构造和展望

直流电弧炉冶炼是当今世界各国竞相研究开发的一项新技术,本文根据世界各大公司直流电弧炉开发的现状,着重阐述了直流电弧炉的特点、炉底电极构造和电力输入,并结合国内现状谈了自己的体会。     

ABB公司直流炉导电炉底

ABB与RADEX公司经多年试验和不断改进，开发出颇具特色的由导电砖砌筑的直流电弧炉炉底电极，现已成为目前世界直流电弧炉四种主要底电极结构型式之一。在马来西亚槟榔城于1991年11月召开的国际电炉会议上，该公司撰文发表其导电炉底耐火材料开发经过。据有关资料摘要予以介绍。1导电炉底的开发经过从本世纪七十年代起，瑞典的ASEA公司，在其同BBC公司尚未合并之前，即开始进行单电极直流电弧炉的设计。正是ASEA公司1983年将瑞典阿维斯特厂一座50吨的交流电弧炉改造成冶炼钢的单电极直流电弧炉；在同一年把一座1．6kVA的生产铬铁的…     

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。     

直流炼钢电弧炉技术

系统地阐述了直流炼钢电弧炉的炉底电极，电气设备，工艺操作、石墨电极的特点，导电耐火材料与底电极套管砖的特性，泡沫渣，以及直流炼钢电弧炉的设备与工艺的不断完善。     

直流电弧炉底电极的结构型式

世界上直流电弧炉的发展异常迅猛,我国也开始了直流电弧炉的建设。直流电弧炉与交流电弧炉的最大差别,除供电系统多一套可控硅整流装置外,电炉本身的不同就只有炉底结构的区别了,不同的直流电弧炉的形式也是指炉底电极的型式,本文主要介绍底电极的型式。     

60t直流电弧炉炼钢过程的炯分析

基于现代电弧炉炼钢的工艺理论,建立了描述电弧炉炼钢过程的热化学计量模型和炯模型,应用该模型对大冶特钢的60t直流电弧炉冶炼过程进行了模拟,对100％废钢、30％铁水＋70％废钢,64．4％铁水＋35．6％废钢的炉料结构条件下的电弧炉冶炼过程进行了能分析和炯分析。结果表明,兑加铁水可明显降低冶炼电耗,但降低总能量利用率,如考虑回收利用炉气和冷却水物理炯,则电弧炉冶炼过程炯的利用率略有增加。     

Fluid Flow Modeling of Arc Plasma and Bath Circulation in DC Electric Arc Furnace

 A mathematical model describing the flow field, heat transfer and the electromagnetic phenomenon in a DC electric arc furnace has been developed. First the governing equations in the arc plasma region are solved and the calculated results of heat transfer, current density and shear stresses on the anode surface are used as boundary conditions in a model of molten bath. Then a two dimensional time dependent model is used to describe the flow field and electromagnetic phenomenon in the molten bath. Moreover, the effect of bottom electrode diameter on the circulation of molten bath is studied.     

高炉炉缸炉底内衬的等效冷却条件计算方法

建立了高炉炉缸炉底冷却的二维有限元传热模型.该模型能计算紊流水冷冷却器以等效对流换热系数表征的冷却参数,能反解服役炉缸实际冷却强度.等效冷却条件参数可用于缩小多维炉缸传热模型的计算域和规模,且不失边界条件精度.文中设计了参数化有限元建模及分析的计算程序,基于管内紊流水努赛尔特征数,定义一个物性综合系数,构造了更为简明的对流换热系数计算表达式.     

直流电弧炉底电极的设计与应用

本文由电工学、传热学及触针风冷底电极特点，推导出触针底电极根数、直径与最大直流电流的关系式，结合上钢五厂１０ｔ直流电弧炉底电极的设计，说明关系式的应用、注意事项以及底电极冷却所需气体量的确定等。底电极尺寸确定过程虽然是以触针风冷底电极为例，但同样适合于棒式水冷电极尺寸的确定。     

Numerical Simulation of Heat Transfer in Porous Metals for Cooling Applications

Porous metals have low densities and novel physical, mechanical, thermal, electrical, and acoustic properties. Hence, they have attracted a large amount of interest over the last few decades. One of their applications is for thermal management in the electronics industry because of their fluid permeability and thermal conductivity. The heat transfer capability is achieved by the interaction between the internal channels within the porous metal and the coolant flowing through them. This paper studies the fluid flow and heat transfer in open-cell porous metals manufactured by space holder methods by numerical simulation using software ANSYS Fluent. A 3D geometric model of the porous structure was created based on the face-centered-cubic arrangement of spheres linked by cylinders. This model allows for different combinations of pore parameters including a wide range of porosity (50 to 80 pct), pore size (400 to 1000 µm), and metal particle size (10 to 75 µm). In this study, water was used as the coolant and copper was selected as the metal matrix. The flow rate was varied in the Darcian and Forchheimer’s regimes. The permeability, form drag coefficient, and heat transfer coefficient were calculated under a range of conditions. The numerical results showed that permeability increased whereas the form drag coefficient decreased with porosity. Both permeability and form drag coefficient increased with pore size. Increasing flow rate and decreasing porosity led to better heat transfer performance.     

垃圾焚烧灰电弧熔融炉热工特性的研究

利用处理量为2 kg的直流电弧炉对医疗垃圾焚烧灰进行熔融实验研究。考察了电弧长度对弧电压、弧电流、熔池直径、熔融时间和电能单耗的影响。结果表明:随着弧长增大,弧电压呈近似线性增长,弧电流下降,熔池直径增大,熔融时间缩短,电能单耗降低。因此,在保证电弧稳定的前提下,应尽量采用长弧操作;与单独底灰熔融相比,飞灰/底灰混合熔融时的最大弧长较大,电能单耗较低;不足之处在于石墨电极单耗稍大。     

Mathematical and physical modelling of fluid flow and heat transfer in electric smelting

Heat and momentum transfer in a submerged electric smelting furnace were investigated in a physical model, using oil and an aqueous calcium chloride solution to simulate the slag and matte phases, respectively. Gas evolution at the electrode was simulated by the injection of gas through the electrode in the model. A mathematical model for fluid flow and heat transfer in the model was also developed. The measured temperature distributions near the oil⧹solution interface could only be reproduced in the mathematical model by the imposition of a no-slip boundary condition at the interface. This condition impedes the transfer of heat and momentum into the lower phase; the implications for smelting are discussed.     

Decision making: the context of nurse prescribing

BACKGROUND: Alterations in body temperature result from changes in tissue heat content. Heat flow is a complex function of vasomotor status and core, peripheral, and ambient temperatures. Consequently it is difficult to quantify specific mechanisms responsible for observed changes in body heat distribution. Therefore the authors developed two mathematical models that independently express regional tissue heat production and the motion of heat through tissues in terms of measurable quantities. METHODS: The equilibrium model expresses the effective regional heat transfer coefficient in terms of cutaneous heat flux, skin temperature, and temperature at the center of the extremity. It applies at steady states and provides a ratio of the heat transfer coefficients before and after an intervention. In contrast, the heat flow model provides a time-dependent estimate of the heat transfer coefficient in terms of ambient temperature, skin temperature, and temperature at the center of the extremity. RESULTS: Each model was applied to data acquired in a previous evaluation of heat balance during anesthesia induction. The relation between the ratio of steady state regional heat transfer coefficients calculated using each model was linear. The effective heat transfer coefficient for the forehead (a core site) decreased approximately 20% after induction of anesthesia. In contrast, heat transfer coefficients in the six tested extremity sites more than doubled. CONCLUSIONS: Effective heat transfer coefficients can be used to evaluate the thermal effects of various clinical interventions, such as induction of regional anesthesia or administration of vasodilating drugs. The heat transfer coefficient for the forehead presumably decreased because general anesthesia reduces brain perfusion. In contrast, increased heat transfer coefficients in the extremity sites indicate that thermoregulatory and anesthetic-induced vasodilation more than doubles the core-to-peripheral flow of heat. This flow of heat causes redistribution hypothermia, which is usually the major cause of core hypothermia during anesthesia.