环式阳极焙烧炉热工过程的数值模拟

通过对环式阳极焙烧炉的热工过程进行系统理论分析, 建立了焙烧炉热工过程的数学模型. 对焙烧炉进行模拟计算的结果表明 焙烧过程中阳极内部温差最大的地方主要集中在炉顶, 应采取相应的措施减少炉顶的热损失以保持阳极焙烧温度的均匀性; 同时, 不同的火焰循环时间和空气渗漏对焙烧的能耗影响较大, 降低火焰循环时间将导致能耗增加, 而降低空气渗漏量则可极大地降低能耗.     

Three-dimensional turbulent model of heat transfer and fluid flow in GTAW process

A two-equation K-ε turbulent fluid flow model is built to model the heat transfer and fluid flow in gas tungsten arc welding (GTAW) process of stainless steel SUS310 and SUS316.This model combines the buoyancy force,lorentz force and marangni force as the driving forces of the fluid flow in the weld pool.The material properties are functions of temperature in this model.The simulated results show that the molten metal flowing outward is mainly caused by the marangoni convection,which makes the weld pool become wider and shallower.The comparison of the weld pool shape of SUS310 and SUS316 shows that the slight differences of the value of thermal conductivity mainly attributes to the difference of the weld pool shape and the distinction of heat transport in laminar and turbulent model makes large diversity in the simulated results.     

真气垫炉内漂浮换热过程数值模拟及结构优化

气垫炉是一种薄板材热处理用先进设备,基于某铝厂设计的气垫炉结构,建立气垫炉整体的三维计算模型,运用流固耦合FSI分析法对炉内板材漂浮换热过程进行模拟。模拟结果表明,板材换热基本均匀,但板材向下畸变过大,无法实现正常漂浮。为减少板材畸变,在优选空间内采用正交试验法优化气垫炉喷嘴布置参数,并采用响应面法与遗传算法优化气垫炉导流装置结构参数。结果表明,装置优化后板材上下表面的风量、压力分布更为合理,炉内板材畸变量从110.3 mm降低至41.4 mm,板材漂浮得以实现。     

Numerical simulation analysis of Guixi copper flash smelting furnace

A numerical simulation analysis for reactions of chalcopyrite and pyrite particles coupled with momentum,heat and mass transfer between the particle and gas in a flash smelting furnace is presented.In the simulation.the equations governing the gas flow are solved numerically by Eular method.The particle phase is introduced into the gas flow by the particle-source-in-cell technique(PSIC),Predictions including the fluid flow field,temperature field,concentration field of gas phase and the tracks of particles have been obtained by the numerical simulation.The visualized results show that the reaction of sulfide particles is almost completed in the upper zone of the shaft within 1.5m far from the central jet distributor (CJD)type concentrate burner,The simulation results are in good agreement with data obtained from a series of experiments and tests in the plant and the error is less than 2%.     

工业硅真空感应精炼过程数值模拟

用Multi-physics Comsol软件对工业硅真空感应精炼过程的温度场进行了二维数值模拟和分析,定量研究了精炼过程熔池中温度场动态分布特征.结果表明:精炼过程中熔池中存在不均匀的温度场,温度梯度随时间和空间位置发生变化,在保温阶段熔池底部和表面温差最大值为382 K.精炼过程中硅料熔化前后的温度分布明显不同,硅料熔化后电磁搅拌形成的热流场和熔池表面向外的热辐射对精炼过程熔池中温度分布产生了重要影响.     

薄板坯连铸漏斗型结晶器内流动、传热和凝固行为的数值研究

针对薄板坯连铸漏斗型结晶器,建立了钢液流动与凝固传热的三维耦合模型,在不改变造型复杂的水口和漏斗型结晶器的尺寸和结构的前提下,计算分析了不同操作参数——拉坯速度和浇注温度对结晶器内流场、温度场和凝壳的影响,同时采用了第二类和第三类两种不同的热边界条件进行了流场和温度场的分析。计算结果表明,钢液凝固壳及糊状区对结晶器内钢液的流动有很大影响,采用第二类热边界条件能够更真实地反映出结晶器内流动对传热的影响。     

非转移弧等离子体炬传热与流动的数值模拟

以非转移弧等离子体炬为研究对象,对等离子体电弧和阳极的传热与流动进行了数值模拟,并求解了质量方程、动量方程、能量方程、电势方程和磁场方程,获得了等离子体弧的温度、速度和电流密度分布。计算结果表明,阳极内壁面温度变化不大;等离子体炬出口处径向温度和速度分布类似抛物线形分布;提高进气速度或减小电弧电流,均使得电弧阳极斑点向下游移动。     

纵向磁场下GTAW电弧传热与流动数值模拟

针对外加纵向磁场(LMF)下的焊接电弧的传热与流动特性,建立基于磁流体动力学的二维轴对称数学模型,将流体动力学理论与麦克斯韦方程组进行耦合对电弧的温度场、电势场、电弧压力以及电流密度等进行求解,又分别对磁感应强度为0与0.06 T下的阳极热进行定量分析与对比. 结果表明,外加LMF驱动带电粒子旋转并使电弧扩张,其中心出现负压并形成反重力流将阳极热汇聚于阴极附近,同时电弧因高速旋转增大热对流损失,降低焊接热效率.当磁感应强度为0.06 T时,阳极表面的电流密度、热流密度以及电弧压力等由中心分布转化为双峰分布模式.     

Numerical simulation of heat transfer and fluid flow in GTA/Laser hybrid welding

Abstract

In order to understand the temperature fields, cooling rates and mixing in the weld pool, a comprehensive, three-dimensional heat transfer and fluid flow model is developed and tested by comparing model predictions with two sets of experimental data. The first set of data was taken from the literature. The experiments varied the separation distance between the heat sources for three arc current levels at a constant laser power. The second set of experiments analysed the effect of varying laser power for a constant heat source separation distance. The results demonstrate that the distance between the two heat sources significantly affects the cooling rates. The calculated results showed that the hybrid weld pool was very well mixed with strong convection currents resulting from the interaction between the electromagnetic and Marangoni forces. The calculated and experimental results showed that hybrid welding increases the weld pool width and gap bridgability when compared with laser welding. The weld pool depth in hybrid welding was affected mainly by the characteristics of the laser beam. Hybrid weld pool penetration depth is maximised at an optimal distance between the arc electrode and laser beam. The cooling rate increases significantly when the heat sources are separated beyond a critical distance. At close separation between arc and laser, calculations show that the arc radius must be decreased to achieve the observed weld depths.     

A numerical analysis of fluid flow, heat transfer and solidification in the bending-type square billet continuous casting process

A numerical modeling system was developed which can simulate the transport phenomena of a bending type square billet continuous casting process. Fluid flow and heat transfer were analyzed with a 3-dimensional finite volume method (FVM) with the aid of an effective heat capacity algorithm for the solidification. For a complex geometry of the bending type billet caster, a body-fitted-coordinate (BFC) system was employed. The bent structure of the caster allows a recirculating flow to develop in the upper and outer-radius region and the main stream to shift toward inner radius. This causes the thinner solid shell in the inner radius region than in the outer one. Besides standard operation conditions, we have analyzed the results when casting speed, caster shape, and tundish superheat changes. Lower casting speed makes the solid shell thicker by reducing heat flux from the mold. In the vertical caster, solid shell thickness are more uniform than that in the bending-type in entire region. When superheat increases by 5°C, solid shell thickness at the mold exit becomes thinner by 1 mm.     

Numerical simulation of heat transfer and fluid flow of molten metal in MMA–St copolymer lost foam casting process

In this study, a computational fluid dynamics (CFD) code was developed to calculate the filling pattern using volume of fluid (VOF) algorithm with donor–acceptor method for free surface simulation. This algorithm has been modified to include the pressure of the gas produced from foam degradation. For this purpose a heat transfer model and 2D foam degradation model were developed. In heat transfer model, radiation and conduction between foam and molten metal; and convection between gas and molten metal were considered. In order to evaluate the results of simulation, a bench scale casting apparatus was assembled and the casting was conducted in a transparent mold. The effect of several parameters such as coating thickness, foam density and vacuum level on the gap temperature, gap pressure and filling speed was studied with the developed software. It was found that the simulated results are in good agreement with experimental results.     

热送热装工艺的数值模拟

为了研究热送热装工艺过程中铸坯的温度变化和热量得失,优化现场生产制度,以某钢厂的热送热装工艺为依据,利用有限元法建立了倒角坯冷却凝固、辊道运输和在炉加热的二维传热模型,并结合现场测温验证了模型的正确性。结果表明,铸坯在热送过程中会形成角部温度最低、窄面次之、芯部温度最高的类椭圆形温度分布;在炉加热过程中低温区域会由角部逐渐向芯部移动,会逐渐形成角部温度最高、芯部温度最低的类椭圆形分布。在炉加热时,铸坯在加热一段吸热量最大,约占总吸热量的52.01%,对加热影响最大;其次为加热二段,所占比例为35.26%,预热段和均热段吸热量较小。通过对热送热装工艺的数值模拟研究,发现现有工艺存在铸坯在炉加热时间过长的问题,现有工艺下铸坯进入均热段368 s即可出炉,可以通过调节生产节奏或降低炉温的方式,提高产量或降低加热炉能耗。     

铍材激光钎焊过程中熔池流场和热场的动态模拟技术

根据YAG激光钎焊的物理特征,建立了基于旋转高斯体热源与高斯面热源相结合的混合热源模型.通过对铍材钎焊温度场、钎缝断面形状模拟结果与实际热循环曲线以及钎焊接头形状的对比,验证了模型建立的准确性.为了能够反映固液相变过程中潜热等对熔池动态行为的影响,建立了激光钎接熔池流场与热场动态变化过程三维数学模型和适合非稳态、非线性、多相区和强耦合特性的数值求解方法.进一步研究了熔化潜热、预热温度和保护气体剪切力对熔池内流场分布的影响.     

宽断面板坯结晶器内钢水流动、传热和凝固过程的数值模拟

建立了求解宽断面板坯结晶器内的钢液流动、传热和凝固数学模型,研究了不同浸入式水口结构、铸坯宽度、铸坯厚度和拉速等工况条件下,宽断面板坯结晶器内的流动、传热和凝固行为。结果表明：随着铸坯的宽度从1 800 mm增加2 200 mm时,从浸入式水口侧孔出来的射流在结晶器下部的影响范围更广;宽断面结晶器中的浸入式水口结构对不同铸坯断面和拉速下的流动和凝固行为产生较大的影响;在生产中需根据宽断面结晶器的流动及传热特点进行水口结构及工艺参数的优化。     

热等静压机炉内流动传热分析

本文通过数值研究的方法,对热等静压机内的流动与换热情况进行了模拟。通过对炉内复杂几何条件下的建模,采用变物性参数的方法,获得了炉内的温度分布和流动特征。并对炉内快速冷却过程的监控点的变化进行研究。研究结果表明,仿真分析三维模型基本符合需求,网格设计满足仿真分析要求;快冷原理得到初步验证,混合装置结构、原理得到验证,可以进行均匀快速冷却的详细设计和实物验证。     

矿热炉与AOD炉双联法冶炼不锈钢的设计

根据国内外冶炼不锈钢工艺的发展趋势和不锈钢厂与镍铁合金厂的生产工艺特点,以及徐州金象冶金有限公司的实际条件,确定了一套节约能耗、减少成本的生产工艺:立窑烧结—25 000 kVA的矿热炉—酸性炉衬AOD炉—碱性炉衬AOD炉—浇铸或连铸进行不锈钢生产,经分析表明,此工艺具诸多优点,对镍铁行业的发展提供重要参考。     

Investigation of the solute transportation coupled with heat transfer and fluid flow during twin-roll strip casting process

Mathematical model of solute [C] distribution in twin-roll strip casting process has been setup successfully with Calcosoft for the first time. Simulation result shows that in the center of the molten steel pool between the two rolls there is a vortex flow, which is a solute enriched area. But the highest solute concentration position is at the solidification front of the columnar grain zone near the cooling roll surface. Another solute enriched position is in the back flow above the nip point. Combined wit...     

Kinetics of the reactions in the smelting furnace of the Mitsubishi process

In this paper, the authors present the results of theoretical calculations on the rates at which copper concentrate particles and silica particles dissolve in the matte in the smelting furnace of Mitsubishiprocess. Those calculations indicate that the concentrate particles dissolve rapidly in matte, in less than 1 ms, whereas silica particles dissolve at a much slower rate, and they dissolve mainly in the bulk matte in the smelting furnace. Some advantages of bath smelting over flash smelting are given. For more information, contact Zenjiro Asaki, Mitsubishi Materials Corporation, Central Research Institute, 1-297 Kitabukuro-cho, Omiya, Saimtama, 330-8508, Japan.     

全氢退火炉炉内气体流动与换热特性的数值模拟

通过建立三维模型对全氢退火炉炉内循环气体的流动特性和换热特性展开研究。采用正交试验法研究保护气体的流量、炉内温度、钢卷外径3个因素对炉内各处对流换热的影响。结果表明,保护气体流量对炉内各处对流换热影响很大;随保护气体流量增加,炉内各处流量分配比例基本不变。     

Mathematical model of pyritic smelting process for copper-nickel mineral in oxygen top-blown furnace

1　INTRODUCTIONTheideaofrefiningcopperandnickelwithpyriticsmeltingprocessinoxygentop blownfurnacehascomeintobeingforitsachievementinoxygen converterofsteelmaking processfrom 196 0s.Thefirstpyriticsmeltingfurnacewithoxygentop blownsmeltingnickelhadbeenputintoproductionatNorthNickelCo .ofRussianin 1986 .Nowadays ,thistech nologyhasbeenimportedandemployedinJinchuanNonferrousMetalCo .ofChina .Inthepastdecades ,theutilizationofflashsmeltingfurnaceinnonferrous makinghasgotextensivedevelopmen…