氯化法制取的钛白中TiCl_4加热方法的研究——新型的电弧等离子加热方法

用等离子体加热TiCl_4可以解决高温下TiCl_4腐蚀金属材质的问题。本文对TiCl_4气氛中起弧的可能性以及稳弧的等离子装置操作进行了试验。结果表明,TiCl_4气氛中可以起弧,要求比氩气中高3—4倍的起弧电压。新型等离子装置形成复合气体等离子射流,使起弧容易,又可稳定电弧。等离子装置的中心氮流量很低,可满足氯化法制钛白的工艺要求。     

等离子喷焊工艺参数的快速计算方法研究

针对等离子喷焊工艺参数不易调节的问题,研究了可快速确定等离子喷焊工艺参数的计算方法。该方法可快速确定合适的转移弧电流、喷焊速度和送粉速率等参数,容易获得较优的等离子喷焊工艺参数组合。通过在Q235基材上喷焊Ni60a合金粉末,进行不同喷焊层厚度的等离子喷焊工艺实验研究,对该计算方法进行验证。结果表明:使用该方法计算所得的工艺参数,可获得喷焊层与基材结合良好、表面硬度高的喷焊层,其表面最低硬度大于Hv 730,最高硬度可达Hv 804。     

等离子弧热喷焊技术的发展与现状

等离子弧热喷焊技术是一种以等离子弧为热源,以一定成分的合金粉末作为填充金属的表面强化技术。近年来,等离子弧热喷焊技术研究在设备、控制和应用材料几方面都取得了长足的进展。本文介绍了等离子弧热喷焊技术的发展现状和前景展望。     

等离子弧热喷焊技术的发展与现状

等离子弧热喷焊技术是一种以等离子弧为热源，以一定成分的合金粉末作为填充金属的表面强化技术。近年来，等离子弧热喷焊技术研究在设备、控制和应用材料几方面都取得了长足的进展。本文介绍了等离子弧热喷焊技术的发展现状和前景。     

长线束等离子弧喷枪在火法冶金中的应用

本文叙述了有关等离子能源公司(PEC)长线束等离子弧喷枪的特性。并阐述了常用的50、150、500、1000、3500和4500千瓦规格的喷枪。现在各种规格的喷抢可能是传导电弧式或非传导电弧式的。本文还简述了等离子弧喷枪的启动和变换电源的技术。文章通过一些数字和图象来说明长线束等离子弧喷枪在火法冶金上的应用。还选用其它领域应用等离子弧喷枪的情况来进一步强调此种喷枪的优点及益处。文章还简述了等离子弧喷枪的全部加热系统的辅助设施,包括电力供应、水冷系统、供气系统、控制盘和等离子弧启动装置等。     

1100MW机组等离子点火特性的数值模拟

以Fluent软件为计算平台,基于计算流体力学、计算传热学和计算燃烧学的原理,对1100MW机组锅炉采用等离子点火系统,针对设计制造的单角等离子体点火燃烧器煤粉燃烧过程进行气粒两相三维流动、换热和燃烧的数值模拟,预测了不同煤粉空气配比条件下的炉膛内气粒两相流动、温度场分布、气相组分浓度场分布等情况,为机组锅炉等离子点火系统的实际运行提供指导。     

感应等离子弧试验初获进展

等离子技术的开发应用,为高温化工过程提供了一个有力的手段。为探索新的多晶硅生产工艺,上海半导体材料厂正进行感应等离子弧用于还原多晶硅的探讨。第一步工作着手进行氩核氢鞘型感应等离子弧的试验,采用组合式油冷石英灯距,国产 GP100—DL2型高频等离子体发生器,已初步实现     

等离子电弧枪

等离子电弧枪是等离子加热系统的最重要部件,用于起弧并保持等离子弧加热稳定。等离子弧的突出特点是方向稳定,就如同一道光束。 图1所示为德马克等离子枪的剖面图,它具有四大组件:电弧枪座、枪体、电极、喷咀。 枪体的连接头与电弧枪座相连,经快速连接装置集中供给所需的介质,如电、气、冷却水。冷却水由连     

直流电弧电渣钢包炉电磁场速度场温度场的三维数值模拟

应用保角变换，采用贴体坐标，建立了非规范正交曲线坐标系的直流电弧电渣钢包炉钢液与两相流的电磁场、速度场、温度场的三维数学模型，用ψ＾→－ω＾→法进行了联立耦合数值计算，在生产过程中测量电磁场与温度场，预测与实测结果基本一致。     

对弧形连铸115mm×115mm小方坯结晶器的研究

采用数学模型、有限元计算和热光弹实验相结合的方法,对弧形小方坯结晶器的温度场、应力场和磨损情况进行了研究。研究表明,弧形小方坯结晶器内弧一侧除在钢液面的附近有最高温度和热应力值外,下部有第2次高峰值。     

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.     

Effects of metal vapor on electron temperature in helium gas tungsten arcs

In order to investigate the effects of metal vapor on the thermodynamic property of arc plasma in the welding process, electron temperatures in the pure helium plasma and in the helium plasma during welding in gas tungsten arcs (GTAs) were measured by using the laser scattering method. The experimental results showed that metal vapor led to a significant decrease in the electron temperature compared with that of pure helium GTA plasma. The temperature difference reached 6000 K in the arc fringe at the maximum.     

非平衡CO_2-Ar等离子流的光学气流评价（英文）

In this study,spectroscopic measurements of CO2- Ar arc plasma flow are conducted using a hollow electrode arc heated wind tunnel. In CO2- Ar plasma,radiation of C2 Swan band system is predominant. Other molecular and atomic spectra are not observed except Cu spectra which are produced due to the electrode melting. Background continuum radiation is observed and overlapped with C2 Swan band system. Temperature evaluation of CO2- Ar arc plasma flow is conducted by the area intensity method and temperature distribution is obtained along the stagnation streamline around a disk model. It is found that the vibrational temperature is much higher than the rotational temperature in the free stream region due to the vibrational nonequilibrium process. In the shock layer,the rotational temperature increases by about 1 000 K while the vibrational temperature decreases by about 1 000 K. Energy exchange between translation and vibration modes is activated in the shock layer,resulting in the decrease of the vibrational temperature. However,the vibrational temperature is still higher than the rotational temperature,indicating that the vibrational relaxation process is not completed. In conclusion,the thermochemical state of the CO2- Ar arc plasma flow is in the vibrational nonequilibrium state along the stagnation streamline around the disk model.     

变极性电弧焊接的电流换向过程影响因素试验研究

采用基于反向再燃弧电压产生电路的变极性焊接电源为试验平台，研究了电源设备及其控制参数、焊接回路电缆寄生电感和焊接工艺参数对变极性焊接电流换向过程的影响规律. 试验结果表明，提高反向再燃弧电压值能够提升变极性过程的电流变化速率，而较大的焊接回路电缆寄生电感会降低电流变化速率，同时降低变极性结束时的电流值，不利于变极性过程的电弧可靠再引燃和稳定燃烧. 初始焊接电流越小，则变极性过程结束时的电流值越小，增加共同导通时间可以提高变极性结束时的电流值，但同时降低变极性开始时的电流大小. 因此小电流变极性焊接时可采用较大的反向稳压值并适当增加共同导通时间，以增强变极性过程中的电弧稳定性.      

氩氢摩尔比对直流电弧等离子体喷射法等离子体放电特征影响的计算

假定氩-氢等离子体处于局部热力学平衡状态,利用理想气体分子运动论和经典查普曼-恩斯科格(ChapmanEnskog)方法,在获取符合直流电弧等离子体喷射法实际工况的等离子体热力学和输运参数的基础上,基于FLUENT软件进行二次开发,添加电磁场相关的电流连续方程、安培定律等方程及洛伦兹力、焦耳热等源项,模拟研究氩氢摩尔比对等离子体放电特征影响规律.结果表明:在气压为8 k Pa,工作电流150 A,氩氢摩尔比由3∶1降至1∶3时,等离子体最大流速由829 m·s-1增至1127 m·s-1,最高温度由20600 K逐渐降低至16800 K,电弧对基体的加热能力逐渐增强的同时使基体表面温度均匀性变差.在其他条件不变的前提下,氩氢摩尔比为1∶2时能获得适宜金刚石生长且相对均匀的基体表面温度.      

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.     

Characterization of Process Conditions in Industrial Stainless Steelmaking Electric Arc Furnace Using Optical Emission Spectrum Measurements

Emission spectroscopy is a potential method for gaining information on electric arc furnace (EAF) process conditions. Previous studies published in literature on industrial EAF emission spectra have focused on a smaller scales and DC arc furnaces. In this study emission spectrum measurements were conducted for 140t AC stainless steelmaking EAF at Outokumpu Stainless Oy, Tornio Works, Finland. Four basic types of emission spectra were obtained during the EAF process cycle. The first one is obscured by scrap steel, the second is dominated by thermal radiation of the slag, the third is dominated by alkali peaks and sodium D-lines and the fourth is characterized by multiple atomic emission peaks. The atomic emission peaks were identified by comparing them to the NIST database for atomic emission lines and previous laboratory measurements on EAF slag emission spectra. The comparison shows that the optic emission of an arc is dominated by slag components. Plasma conditions were analyzed by deriving plasma temperature from optical emissions of Ca I lines. The analysis suggests that accurate information on plasma conditions can be gained from outer plasma having a plasma temperature below 7000 K (6727 °C).     

Validation of thermal-kinetic-diffusion model for arc plasma surface hardening of steel

Realistic analysis of the surface hardening pocesses during an arc plasma torch application indicates that the events taking place during a plasma torch pass should be properly looked at as a thermal-kinetic-diffusion problem. Arbitrary separation of these components may lead to erroneous evaluation of the variables and parameters that characterise the process. Consequently, a complex finite element model, which describes elementary processes of gas-solid surface interaction by the method of molecular gas dynamics, connects the transfer processes between gaseous and solid phases and takes into consideration thermal and diffusion events in the steel, has been developed. The adequacy of the mathematical model was substantiated by comparing model predictions to measurements made during surface hardening using an arc nitrogen plasma torch. It was proved that the approach gives the possibility to compute with sufficient accuracy the transient distributions of temperature and concentration fields in the steel surface layer during surface hardening using high-enthalpy gas flux.     

Evaporation of reaction-zone components in the low-temperature plasma treatment of chromium-bearing melts

The evaporation of iron, Fe–Cr, Fe–Ni, and Fe–Cr–Ni melts at the plasma spot in treatment by low-temperature argon plasma is studied. Experiments with different masses of metal and with variation in arc power of the plasmatron are conducted so as to determine the conditions corresponding to stable surface temperature of the metal. The results show that, for experiments in which the plasma flux completely exposes the surface of the metal droplet, arc power no less than 2.0 kW is optimal; the mass of the metal should be 5?10 g. The evaporation process is studied as function of the melt composition, and the evaporation rates are determined. Of the alloys considered, Fe–Cr–Ni melt is characterized by the highest evaporation rate in the neutral atmosphere of a laboratory plasma furnace. The surface temperature of the melt is determined indirectly, on the basis of the evaporation rate. The surface temperature of the plasma-treated melt is found to vary in the range 1950–2100 K with variation in arc power from 1.6 to 2.4 kW.     

60 kg/m钢轨热轧过程的三维有限元模拟

采用非线性有限元软件MARC/AutoForge，通过三维弹塑性热力耦合的有限元方法模拟了重轨800-I孔的变形过程，分析了轧件上等效应力、应变场、温度场和轧制力。轧件最大变形值于帽形腰腿圆弧和两侧腿尖处，在轧件中部靠近表面区域升温最大。