鱼雷罐双枪喷吹脱硫新工艺水模试验研究

针对鱼雷罐喷吹脱硫动力学条件差,引起脱硫剂消耗高、铁液回硫比例大等问题,提出了一种鱼雷罐双枪斜插式喷吹脱硫新工艺;通过水力学模型试验,对比研究了原工艺和新工艺的脱硫动力学条件,以及工艺参数对熔池混匀时间的影响规律。结果表明:相比目前使用工艺,新工艺可以大幅度缩短熔池内液体混匀时间,显著改善喷吹动力学条件,提高脱硫效果;试验条件下,混匀时间改善最大幅度达53.8%。     

120t顶底复吹转炉水模型优化研究

以某厂120 t顶底复吹转炉为原型,依据相似原理,在保证模型与原型几何相似以及动力学相似的条件下,通过水力学模型试验研究了顶吹气体流量、底吹气体流量及氧枪位置对熔池混匀时间和冲击深度的影响。结果表明:当顶吹流量为104. 4 Nm~3/h、底吹流量为1. 41 Nm~3/h、氧枪位置为177 mm时,熔池的混匀时间最短,冲击深度约为熔池深度的1/2,处于合理范围之内。基于水模型试验结果进行了工业试验,结果表明:工艺参数优化后顶底复吹转炉冶炼的技术指标明显改善,120 t转炉的吹炼时间从13. 72 min缩短至12. 86 min,终渣(T. Fe)质量分数从16. 33%降低至12. 16%。     

50t顶底复吹转炉的水力学模型实验研究

通过50t顶底复吹转炉水力学模型实验,研究氧气顶底复吹转炉顶枪枪位、底吹气体流量对转炉熔炼过程中熔池搅拌和时间以及对冶炼过程的喷溅及熔池的冲击深度影响。结果表明,当模型枪位在120～210mm,实际枪位1．00～1．56m;模型底吹流量控制在0．38Nm^3／h,实际底吹流量控制在146～190Nm^3／h左右时,熔池混匀时间短,吹炼时喷溅量少。较浅的熔池冲击深度就可达到良好的搅拌效果,有利于避免冲击炉底。当冲击深度较大时,混匀时间反倒增加。     

转炉预直炼法脱磷期亚音速顶吹的物理模拟

在1∶6物理模型上，通过水模型实验，对梅钢复吹转炉亚音速喷吹条件下的熔池搅拌情况进行了研究。结果表明，亚音速喷吹条件下的熔池均混时间明显长于超音速的。在亚音速喷吹条件下降低枪位、增加顶底吹气体流量可降低均混时间；A2底吹为本实验最佳布置方式，A6为适合预直炼的布置方式。     

转炉熔渣中底吹气体搅拌行为研究

采用数值模拟方法,研究了转炉溅渣护炉前向熔渣底吹气体过程喷嘴个数、底吹流量以及底吹位置对熔池中流场的影响规律。结果表明,采用四喷嘴,控制底吹流量1.14 m·s~(-1),能获得混匀时间短、成分较均匀的良好流场。在熔池尺寸较大时,偏心底吹流场影响较小。     

不锈钢冶炼用AOD炉内的射流行为和流体流动

在分析氩一氧脱碳（AOD）炉内侧吹射流行为特征的基础上,建立了描述AOD炉内三维流动的数学模型,考察了喷吹气体流量和喷枪布置对AOD熔池内湍流场的影响规律．结果表明,供气强度对AOD炉内射流流股轨迹和钢液流动产生明显影响;多枪喷吹,使熔池中流场和湍动能分布变得更加合理．计算结果与物理模型的观测结果吻合．     

150t底吹氩钢包插入浸渍管混匀时间模拟研究

以某厂150 t底吹氩钢包为原型,建立插入浸渍管钢包底吹气体钢液流场数学模型,利用Mixture多相流模型对钢包吹氩过程进行数值模拟计算。分析了钢包底吹氩过程中钢液的流动行为及吹氩量对合金混匀时间的影响,计算了插入浸渍管对合金混匀时间的影响。结果表明:无浸渍管,吹氩量小于250 L/min时,随着吹氩量的增加,混匀时间迅速变短,而气量大于250 L/min时,混匀时间随供气量变化不明显。插入浸渍管后,同一吹气量时,能够缩短混匀时间、加强冶炼效果。     

转炉熔池中废钢对混匀影响

基于250 t转炉的物理模拟的方法研究转炉冶炼初期废钢对熔池搅拌的影响,并考察废钢不同加入量和分布方式对熔池搅拌的影响。研究结果表明,熔池内添加或不加废钢时,随着底吹供气量的增加,熔池混匀时间逐渐减小;对于废钢集中分布或均匀分布,熔池的混匀时间随着供气量的增加均会减少。在相同的供气量下,废钢均匀分布的混匀时间比集中分布时的要短;对于轻废钢的情况下,熔池混匀时间随着供气量增加而下降,但重废钢量增加到某一重量时(50 t),混匀时间变化出现相反的趋势,混匀时间不仅不增加,反而相对(加入10～25 t)减少。     

倒T形脱硫喷枪使用过程温度场数值模拟研究

利用ANSYS等有限元分析软件对倒T形脱硫喷枪5次脱硫循环过程中的温度场进行了数值模拟研究,探讨了喷抢潜入铁液段截面上温度分布和变化规律,为喷枪热应力分析奠定了基础.结果表明,脱硫喷枪整体温度随着喷枪使用次数的增加不断上升并逐渐趋于稳定;喷枪外层耐火材料温度变化剧烈,而内层耐火材料的温度变化则较为平缓,并相对于外层耐火材料在时间上有一定延迟;喷吹过程中,喷枪径向温度梯度较大,周向温度分布随距加强筋距离的增大而逐渐升高;而自然冷却过程中,喷枪径向最高温度出现在耐火材料中层,周向温度分布基本无差别.     

插入浸渍圆筒钢包底吹气体优化研究

以150 t钢包为原型,采用水模型实验的方法研究插入浸渍圆筒底吹钢包内钢液的卷渣现象,研究了底吹气量、浸渍圆筒直径及插入深度对钢液卷渣及均混时间的影响。同时建立钢包底吹气体钢液流场数学模型,利用Mixture多相流模型对钢包吹氩过程进行数值模拟计算,分析不同底吹气量下插入浸渍圆筒钢液的流动状态和钢液表面的卷渣。通过水模拟和数值模拟比较,结果表明:插入浸渍圆筒后,增大了临界卷渣吹气量,加强了熔池搅拌,更有效地缩短了混匀时间。     

150 t钢包底吹氩气物理模拟

为评估国内某钢厂150 t钢包底吹氩工艺中供气流量、比例和底吹元件类型对精炼工艺的影响,建立了1:4物理模拟模型,研究了总供气量、供气方式和底吹元件类型对混匀时间的影响。结果表明,随总供气量的增加,使用两种类型底吹元件的钢包混匀时间下降,在小气量下使用弥散型底吹元件混匀时间小于狭缝型,较大气量下两者相反,且使用狭缝型底吹元件混匀时间受供气方式影响更大。试验条件下离钢包中心较远的底吹位置使用较大的底吹流量有利于混匀。     

Parametric study of gas−liquid two-phase flow field in horizontal stirred tank

Based on Fluent software, the gas?liquid two-phase flow in the horizontal stirred tank was simulated with SST k?ω turbulence model, Eulerian?Eulerian two-fluid model, and multi-reference flame method. The mixing process in the tank was calculated by tracer method. The results show that increasing the rotating speed or gas flow is conducive to a more uniform distribution of the gas phase and accelerates the mixing of the liquid phase. When the rotating speed exceeds 93 r/min, the relative power demand remains basically constant. The change in the inclination angle of the upper impeller has minimal effect on the gas phase distribution. When the inclination angle is 50°, the relative power demand reaches the maximum. An appropriate increase in the impeller distance from the bottom improves the gas holdup and gas phase distribution but increases the liquid phase mixing time.     

3D numerical investigation of effects of density and surface tension on mixing time in bottom-blown gas-stirred ladles

In molten phase metallurgical processes, mixing via gas injection has a vital role in obtaining a homogeneous product. The efficiency of mixing depends on operational variables such as gas flow rate and slag height as well as physical properties of the molten phases. A numerical simulation is conducted to study the above parameters in the flow behavior of a bottom-blown bath. The molten metal and the slag are modeled by water and oil, respectively. The numerical results, particularly the mixing time, are validated against experimental data. The results show that mixing time increases as the slag height increases and decreases as the density of the slag material increases. The mixing time decreases with an increase in the density of the primary phase; however, it increases as the surface tension between air and water increases. A case with properties close to a real molten metal is also modeled. The performance of the system is influenced by the momentum rather than the dissipative forces. Thus, the effect of the density of the molten phase on the mixing process is more pronounced compared to the effect of the surface tension between the air and the molten phase.     

Three Dimensional Modeling of the Plasma Spray Process

Results of simulations of three-dimensional (3D) temperature and flow fields inside and outside of a DC arc plasma torch in steady state are presented with transverse particle and carrier gas injection into the plasma jet. The results show that an increase of the gas flow rate at constant current moves the anode arc root further downstream leading to higher enthalpy and velocity at the exit of the torch anode, and stronger mixing effects in the jet region. An increase of the arc current with constant gas flow rate shortens the arc, but increases the enthalpy and velocity at the exit of the torch nozzle, and leads to longer jets. 3D features of the plasma jet due to the 3D starting conditions at the torch exit and, in particular, due to the transverse carrier gas and particle injection, as well as 3D trajectories and heating histories of sprayed particles are also discussed.     

RH真空精炼循环流动特性的水模型研究

以某RH精炼装置为原型,基于相似原理建立了1:7的水模型,对RH精炼过程钢液循环流动行为进行研究.考察了提升气体流量、浸渍管插入深度对RH内循环流量和混匀时间的影响规律,分析了循环流量和混匀时间的关系.     

Mathematical Modeling and Experimental Validation of the Warm Spray (Two-Stage HVOF) Process

The warm spray (WS) gun was developed to make an oxidation-free coating of temperature-sensitive material, such as titanium and copper, on a substrate. The gun has a combustion chamber followed by a mixing chamber, in which the combustion gas is mixed with the nitrogen gas at room temperature. The temperature of the mixed gas can be controlled in the range of about 1000-2500 K by adjusting the mass flow rate of nitrogen gas. The gas in the mixing chamber is accelerated to supersonic speed through a converging-diverging nozzle followed by a straight barrel. This paper shows how to construct the mathematical model of the gas flow and particle velocity/temperature of the WS process. The model consists of four parts: (a) thermodynamic and gas-dynamic calculations of combustion and mixing chambers, (b) quasi-one-dimensional calculation of the internal gas flow of the gun, (c) semiempirical calculation of the jet flow from the gun exit, and (d) calculation of particle velocity and temperature traveling in the gas flow. The validity of the mathematical model is confirmed by the experimental results of the aluminum particle sprayed by the WS gun.     

Fluid flow and mixing behavior in gas stirred ladle with submerged lance

A numerical study for analyzing both fluid flow and mixing behavior in gas-stirred ladles with a submerged lance was performed. At first, the shape and volume of the plumes generated by the submerged nozzle were calculated. Subsequently, the fluid flow driven by these plumes, and the mass transfer in the ladle were calculated by a three dimensional turbulent simulation program. Water model experiments for the velocity measurements were performed to verify the accuracy of the calculation results. It was shown that as the gas flow rate increases, the downward velocity at the ladle wall increases and mixing time decreases. Mixing time is sensitive to the alloy addition position especially at a lower gas flow rate. The result suggested that the alloy should be added at the plume zone close to the center at the melt surface     

TC4钛合金不同气源激光渗氮行为

在用矩形光斑高功率半导体激光器,在纯氮气和氮氩混合两种不同方式下,通过不同气流量和氮氩混合对Ti-6Al-4V进行表面渗氮,研究气体流量、氮氩混气比对渗氮熔池形态及渗氮组织和力学性能的影响。采用SEM、EDS以及XRD对渗氮层的显微组织、微区成分及相组成进行研究。结果表明:采用纯氮渗氮时,在15 L/min气流量下获得均匀渗氮层,继续增大气流量渗氮熔池流动紊乱,出现贯穿裂纹,且渗氮深度和硬度并未随气流量增加;采用不同氮氩混气比渗氮时,渗氮层的表层硬度均较相同条件下纯氮气渗氮层的有所降低,且渗氮层裂纹倾向减弱,渗氮层组织由表至里在200~800μm内按层深依次存在TiN0.88、TiN0.61、TiN0.3三种稳定相;分别采用纯氮气和不同氮氩混气比渗氮时,渗氮层组织沿层深分布依次均为粗短树枝晶、等轴晶、细长树枝晶、针状晶。     

Combustion in flash smelting furnaces

The reaction shaft is the heart of a flash smelter. Current knowledge of the combustion of concentrate and ancillary fuels (coal, oil, and gas) in flash smelter shafts comes from laboratory studies, plant measurements, and physical and mathematical modeling. The latter is particularly useful when considering the complications of two-phase flow of particles and gas and chemical reactions; however, uncertainty as to effective particle size requires validation to establish confidence in the model outcomes. Those issues are addressed in the paper, together with the importance of the burner in achieving good mixing and dispersion. Simulations, which may be viewed on the web, show the consequences of poor mixing. For more information, contact Frank Jorgensen, CSIRO Division of Minerals, Box 312, Clayton South, VIC 3169, Australia; +61-3-9545-8531; fax +61-3-9562-8919; e-mail frank.jorgensen@minerals.csiro.au.     

Computational Fluid Dynamics (CFD) Simulations on Multiphase Flow in Mechanically Agitated Seed Precipitation Tank

The large-scale mechanically agitated tank has been widely used in the decomposition process of sodium aluminate solution in the alumina industry. The mixing process in three types of seed precipitation tanks (Robin, Ekato, and improved Ekato) stirred with multiple impellers was compared by using computational fluid dynamics, respectively. The flow field, solid distribution, mixing time, and power consumption were numerically simulated by adopting a Eulerian granular multiphase model and a standard k-ε turbulence model. A steady multiple reference frame approach was used to represent impeller rotation. Compared with the Robin tank, the Ekato tank can generate an axial circulation loop, which is better for fluid mixing and solid suspension; meanwhile about half of the power can be saved. With future improvements in the Ekato tank, the fluid mixing and exchanging can be enhanced under the interaction of a lengthened Intermig impeller coupled with sloped baffles. With a little increase in power consumption, the maximum of the relative solid concentration difference in the whole tank can be maintained within 3%, which meets the design requirement.