蓄热式钢包烘烤热行为的数值模拟和[NOx]排放特性

为了研究蓄热式钢包烘烤的空气和煤气的预热温度对高温空气燃烧过程的影响,耦合了烘烤过程中流体流动、换热和燃烧过程,用数值模拟方法建立了三维立体数学模型,利用计算流体力学软件Fluent,采用有限元差分法和修正速度—压力相耦合的算法Simple,计算了钢包内的燃烧现象,得出了在不同预热温度时,燃烧室内气体温度场和氧气浓度场的分布。结果表明,提高气体预热温度有利于加快燃烧进程,可提高炉内的整体温度及温度的均匀性,降低局部氧浓度,利用高的烘烤效率减少[NOx]的排放。     

Thermodynamic modeling of antimony removal from complex resources in copper smelting process

This work investigated the reaction mechanism of Sb in copper smelting process. The difference of multi-phase distribution of Sb in four typical copper smelting processes was analyzed. A multi-phase equilibrium model of the oxygen-enriched bottom-blow copper smelting process was developed. The impacts of Cu, S, and Sb concentrations in raw materials on Sb distribution in multiphases were researched. This model was also used to investigate the effect of process factors such as copper matte grade, oxygen-enriched concentration, smelting temperature, and oxygen/ore ratio (ratio of oxygen flow rate under standard conditions to concentrate charge rate) on Sb distribution behavior. The results showed that calculation data were in good agreement with the actual production results and literature data. Increasing the Cu content and decreasing the S and Sb contents in the concentrate, increasing the copper matte grade, oxygen/enriched concentration, and oxygen-ore ratio, and at the same time appropriately reducing the smelting temperature are conducive to the targeted enrichment of Sb into the slag. Modeling results can provide theoretical guidance for the clean and efficient treatment of complex resources and the comprehensive recycling of associated elements.     

Thermodynamic modeling of lead blast furnace

A thermodynamic model was developed to predict the distribution behavior of Cu, Fe, S, O, Pb, Zn,As, and the heat balance in a lead blast furnace. The modeling results are validated by the plant data of a lead smelter in Kazakhstan. The model can be used to predict any set of controllable process parameters such as feed composition, smelting temperature, degree of oxygen enrichment and volume of oxygen-enriched air. The effects of the blast air, industrial oxygen, and coke charge on the distribution of Cu, Fe, S, O, Ph, Zn, As, the heat balance, and the lead loss in slag, were presented and discussed.     

中频炉和VOD双联法冶炼不锈钢工艺

介绍了中频炉熔炼及VOD精炼X3CrNiMoN27-5-2不锈钢的生产工艺及措施.采用优质原材料,调整化学成分及出炉温度,控制VOD精炼炉吹氧真空度、吹氧强度、吹氧时间、氩气流最等工艺参数,并结合氧势图和废气温度,准确判断吹氧终点时间和极限真空保压时间,其冶金效果可以达到铸件材质的质量标准.     

高温空气燃烧炉内燃烧特性的数值研究

采用数值模拟法,研究了高温空气燃烧炉内不同空气预热温度、氧气浓度和燃气入口温度对火焰特性和NOx生成和排放的影响规律。研究表明,在提高空气预热温度、降低氧气浓度条件下,在较大范围内进行燃烧,火焰体积变大,炉内温度的峰值相应降低,温度分布更均匀,NOx的生成量大幅度降低。提高燃气入口温度,可抑制燃料和空气在主燃烧区的混合,使火焰内反应物的分布更加均匀,抑制了热力NO的生成,从而减少了NOx的排放量。     

高投料量下炼铜闪速炉内熔炼过程的数值模拟

以FLUENT 6.3为计算平台,建立了铜闪速炉熔炼过程数值模型,并针对高投料量下反应塔气粒两相变物理场信息分布变化特点展开仿真研究。结果表明:工艺风入炉后迅速膨胀,并在反应塔中心形成轮廓明显的主体气流柱;主体气流柱内外的温度和氧浓分布梯度变化较大;局部低温出现在精矿喷嘴下方,而高温反应核心区域则下移至反应塔中下部。综合多场耦合仿真结果可知:高投料量条件下精矿粒子与反应配风之间混合力度欠佳是造成高投料量反应塔内熔炼过程反应效率降低的主要原因。     

Accelerating column leaching trial on copper sulfide ore

The main measures to accelerate leaching sulfide ore are large spraying intensity,manual oxygen supply,temperature control,and acclimated bacteria.The indoor experiment accelerating sulfide ore leaching detected the temperature during leaching process,dissolvability of oxygen,bacterial concentration,Cu concentration and slag grade.At the same time,this paper also analyzed the effect of four factors,which are bacterial diversity cultivation stage,spraying intensity,air supply,and whether to control temperature,on the leaching efficiency of copper.The results indicate that the oxygen content of leach solution has a close relationship with temperature but it is rarely affected by air supply.The bacterial concentration preserves from 106 to 107 mL^-1,and temperature has a great effect on the bacterial activity under the condition of proper temperature and oxygen supply,and the lack of nutrition prevents the bacterial concentration from rising in the late stage.The relationships of the copper leaching efficiency to temperature,air feed,and spraying intensity are directly proportional.The leaching efficiencies of the cultivated bacteria and acclimation bacteria are 1.2 and 1.4 times as large as that of the original bacteria.     

低氧分压系统及其在二元合金选择性氧化中的应用

根据氧化锆陶瓷管材在高温（〉８７３Ｋ）时，因管壁内外的氧分压下同形成氧浓差电池（Ｐｔ，Ｏ２（Ｐ＾ＩＯ２）│ＺｒＯ２│空气（Ｐ＾ＩＯ２），Ｐｔ的原理，研制了可控氧分子（Ｏ２）发射量的低氧分压发生系统。用该系统对Ｎｉ２０Ｃｒ合金进行低氧分压预氧处理后，促进了Ｃｒ在１２７３Ｋ时的选择性氧化，提高了合金的抗氧化性能，在低氧分压下，Ｃｕ１．５Ａｌ合金发生了Ａｌ的选择性内氧化。     

富氧燃烧条件下钢坯加热特性的数值模拟

以某轧钢厂步进式加热炉为研究对象,利用Fluent软件对炉内气相流动与燃烧和钢坯加热过程建立数学模型,并开发了用户自定义函数处理钢坯移动。炉膛内气体流动采用Realizable k-ε模型,燃烧过程采用非预混燃烧模型,辐射传热采用DO模型来计算。通过所建立的数学模型,模拟研究了氧气体积分数为21%～35%的助燃气体与燃料燃烧对钢坯加热特性的影响。结果表明,随着氧气浓度的增加,燃烧区的烟气温度逐渐升高,导致钢坯具有更快的升温速率;由于富氧燃烧在燃烧区产生了更均匀的温度场,因此在氧气浓度为35%时,钢坯的黑印温差仅为15 K,比空气工况下的黑印温差低了20 K;当助燃气体中氧气体积分数从21%增加至35%时,钢坯的辐射传热量也随之增加,加热炉热效率从41.1%提高至48.4%。     

The effect of oxygen on transitional Marangoni flow in laser spot welding

Owing to its significant influence in heat and mass transfer, liquid metal flow during stationary laser welding has been studied for different concentrations of oxygen in the surrounding environment. Two predominant types of surface flow motion are observed: an inward flow, corresponding to a positive surface tension temperature gradient, and an outward flow, corresponding to a negative gradient. Time-dependent changes in oxygen concentration at the surface are observed to flip the surface tension temperature gradient from negative to positive under appropriate shielding conditions. The oxygen concentration affects not only the flow motion, but also the laser absorption coefficient, which increases with increasing environmental oxygen concentration. It is shown here that the evolution of dissolved oxygen in the weld pool as a function of temperature can have a profound influence on the fluid flow and hence on energy transport.     

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%.     

基于遗传算法的铜闪速熔炼过程控制优化

基于已建立的铜闪速熔炼神经网络模型,以能耗费用最低为目标,在工艺指标控制范围内,采用遗传算法对铜闪速熔炼过程的工艺参数进行了仿真优化计算。结果表明,当空气、分配风、工艺氧和中央氧的市场价格折合比值分别为0.05、0.1、0.4和0.45,精矿量为128 t,其成分(质量分数)为Cu 20.61%、S 27.59%、Fe 24.72%、SiO2 11.64%和MgO 1.39%时,铜闪速熔炼工艺参数的遗传优化值为空气15 011 m3、分配风1 302 m3、工艺氧17 359 m3、中央氧1 000 m3、熔剂13.6 t;与实践平均值相比,若采用优化工艺参数控制,熔炼能耗费用可降低4.6%。     

氧气底吹铜熔池熔炼过程的机理及产物的微观分析

对氧气底吹熔炼过程气体喷吹行为、造锍熔炼化学反应机理及熔炼炉内热工作状态进行理论分析及水模型实验和取样分析验证。结果表明,氧气底吹气流能使熔体形成均匀的扩散区,实现熔体的搅拌,在气体连续相区和液体连续相区,气液、液液之间的相互作用强烈,为炉内化学反应及传热传质提供了良好的动力学条件;氧气底吹熔炼过程在零配煤的情况下能达到自热熔炼,在节能减排方面,该工艺具有很强的优势;获得了铜渣、冰铜和蘑菇头中各组分的形貌,确定了铜渣、冰铜和蘑菇头的物相组成,渣样主要由冰铜相、磁铁矿相、铁橄榄石相和玻璃体相组成,熔炼内的氧势和硫势分布有利于反应的进行,能有效抑制Fe3O4的形成以及降低渣含铜。     

Corrosion of oxygen-doped tantalum by lithium

The increase in the penetration of tantalum by liquid lithium with increasing oxygen content of tantalum results from the ability of lithium to extract oxygen from tantalum oxides and/or from regions of high oxygen concentrations, accompanied by the creation of minute channels. At low oxygen concentration, oxides are present primarily at the grain boundaries and the lithium penetration is primarily intergranular. At high oxygen concentration, oxides and/or regions of high oxygen concentration are present both at the grain boundaries and within the grains; lithium penetration is both intergranular and transgranular. For a specific oxygen concentration, the severity of corrosion decreases with increasing temperature because (a) the oxygen solubility increases with temperature, decreasing the number of oxide particles and/or regions of high oxygen concentration, and (b) the diffusivity of oxygen in tantalum increases, allowing more rapid oxygen removal at the tantalum lithium interface.     

Modelling of the oxide scale formation on Fe-Cr steel during exposure in liquid lead-bismuth eutectic in the 450–600 °C temperature range

Previous studies showed that the oxidation of T91 (Fe-9Cr martensitic steel) in liquid Pb-Bi eutectic leads to the formation of a duplex oxide layer containing an inner Fe_2.3Cr_0.7O₄ spinel layer and an upper magnetite layer. The magnetite layer is easily removed by the Pb-Bi flow when the oxygen concentration is low and the flow velocity is high. This phenomenon is not currently understood. The magnetite layer growth rate is limited by the iron diffusion in the oxide layer lattice. The Fe-Cr spinel layer grows in the nanometric cavities formed at the Fe-Cr spinel /T91 interface by the outwards diffusion of iron. Due to this mechanism the growth rate of the Fe-Cr spinel layer is linked to that of magnetite. A modelling of this mechanism is presented. The modelling is in agreement with the experimental data in the case of a high oxygen concentration. However, the calculated oxide scale thicknesses are systematically lower than the experimental values in the case of a low oxygen concentration when the iron diffusion only occurs via interstitials in the oxide scale. Consequently, the estimation of the iron diffusion coefficient, when diffusion occurs via interstitials, is not reliable. To have a better estimation of this iron diffusion coefficient in the Fe-Cr spinel, when diffusion occurs via interstitials, a fit is done using experimental data coming from the European DEMETRA project. Although this evaluation is only based on a fit on the experimental data, it permits to estimate the oxide layer growth kinetics in case of the formation of the described duplex oxide layer, for each oxygen concentration (leading to a vacancy and/or an interstitial diffusion), each temperature between 450 and 620 °C and each hydrodynamic flow. This model shows that the hydrodynamic flow affects the corrosion rate only by the removal of the upper magnetite layer leading to an increase of the oxygen concentration at the spinel/magnetite interface. The oxidation mechanism is thus neither changed by the Pb-Bi flow nor by the oxygen concentration. However, the oxygen concentration modifies the iron diffusion process in the oxide lattice.     

开放条件下气流对激光重熔过程中氧化行为的影响

在激光加工过程中,保护气和载粉气对熔池氧含量有很重要的影响,为了减少在开放条件下激光加工过程中产生的氧化,需要研究保护气和载粉气工艺参数对激光加工过程中氧化行为的影响。以激光重熔45钢为例,通过测定熔池上方气氛以及重熔后基材表层的氧含量,对比研究了不同保护气流量、载粉气流量和离焦量对激光重熔过程中氧化行为的影响。结果表明：气流量较低时,气流卷吸周围空气,载粉气流量、保护气流量以及离焦量升高会加剧激光重熔时的氧化。当载粉气流量超过84 L/min时,大量氩气对周围空气进行了稀释,熔池上方气氛中的氧含量会有所降低。但是保护气流量过高会加剧熔池飞溅。降低熔池上方气氛中氧含量的气流量工艺参数为：保护气流量8.5 L/min,载粉气流量6.5 L/min。     

大空间焊接厂房置换通风效果试验

对某置换通风焊接整体厂房进行了气流组织试验,在正常工况下测试了温湿度、臭氧浓度、室内压强、室内风速、送风风速、回风口风速等数据,并采用发烟法进行了流场显示。发现该厂房采用置换通风方式温湿度分布均匀,臭氧浓度、室内压强、工作区风速均达到设计要求,但测试数据和发烟法试验结果显示,回风效果还有待改善,这与回风管水力失调有关,表明调节对于置换通风厂房的气流组织十分重要。试验结果为大空间厂房置换通风气流组织的研究提供了可靠的数据资料。     

多功能超音速火焰喷涂粒子特性的数值模拟

通过建立多功能超音速火焰喷涂火焰流场的数值模型,对超音速火焰喷涂粒子的速度特性和温度特性进行数值模拟,其结果揭示了多功能超音速火焰喷涂粒子的速度和温度的变化规律.根据数值模拟结果分析了粉末粒度对火焰焰流速度和温度的影响,用不同粒度参数重复模拟计算,这对喷涂粉末的加速和加热性能具有重要意义.     

超音速火焰喷涂流场有限元分析

在液体火箭发动机原理的基础上,建立了超音速火焰喷涂过程全流场分析模型,对KY-HVO(A)F多功能超音速火焰喷涂系统进行了流场分析,得到了HVOF与HVAF两种状态下燃气的速度、温度分布,分别体现了燃气欠膨胀与过膨胀的特点。在HVOF状态计算结果中有8个马赫锥而实际焰流照片中有8～9个马赫锥,所处位置基本对应,可以合理解释喷涂过程的激波现象,不同截面上的速度分布,体现了燃气速度在径向截面上的自模特性。     

高精度坐标镗床伺服电机温度主动控制装置研发与运用

针对高精度坐标镗床伺服电机温升影响机床精度问题,研发伺服电机温度主动控制装置。使用PLC程序实时读取电机内部温度,与室温进行比较,由程序控制在4种不同模式下调节比例阀控制冷却气体流量,并在冗余环路连接方式下使用传感器对各冷却口流量进行监控,实现闭环控制,使得电机温升幅度和速度得到抑制,同时在冷却气流影响下使电机周围温度场快速均衡。