高效低污染燃气燃烧器燃烧特性的数值模拟

运用流体动力学软件Fluent6.3对自行设计的燃气燃烧器的燃烧性能进行了数值模拟研究,分析了不同外圈助燃空气和中心辅助空气配比条件下炉膛内的速度场、温度场以及NOX的生成情况,并对试验结果进行了验证.结果表明,采用适当的外圈助燃空气和中心辅助空气比例,该旋流燃烧器的燃烧性能稳定,燃料燃烧完全,烟气中可燃成分比例不超过0.06%(600 ppm);炉膛内温度分布相对均匀,炉内气体温度偏差不超过30℃,满足高效燃烧的要求;烟气中NOX的含量平均不超过0.006%(60 ppm),远远低于国家排放标准,可以很好控制燃烧产物对大气的污染.随着外圈助燃空气和中心辅助空气的比例增大,炉膛最高温度和平均温度降低,NOX生成量降低,加入空气总量增大,系统的热效率有所降低,但燃烧器产生的高温高速气流,强化了炉内的对流传热,可提高炉子生产率.     

U型蓄热式辐射管表面温度分布数值模拟研究

以一支燃烧能力为58kW的蓄热式辐射管为对象，利用商业CFD软件CFX4．3对蓄热式辐射管表面温度分布进行数值模拟，并进行试验验证，重点分析了辐射管沿长度方向温度分布的规律及其影响因素。结果表明，高速煤气射流产生的湍动燃烧动力，能搅拌炉膛、消除炉内的温差，有利于提高烟气的加热能力，改善其加热性能。但煤气喷射速度不能无限制增大，对于该类型的蓄热式辐射管燃烧器，煤气喷射速度可限制在80m／s～110m／s。     

套筒式陶瓷燃烧器内燃烧过程数学模型

应用湍流扩散火焰燃烧模型，对套筒式陶瓷燃烧器燃烧室内的燃烧过程进行了计算机模拟研究，确定了燃烧过程中煤气空气及燃烧产物的速度分布，温度２和各组分的浓度分布，得到了燃烧过程中火焰的形状和长度。     

铸造用焦及提高冲天炉熔炼质量的研究

作者用我国新近研制成功的铸造焦,进行了底焦燃烧规律试验和生产熔炼试验.对几种质量不同的焦炭的底焦燃烧情况和熔炼效果进行了对比;特别是对焦炭的灰分含量、固定碳含量、含硫量、焦炭的强度、气孔率和反应性等对底焦燃烧及熔炼效果的影响,进行了深入的研究,并分析了铸造焦获得高温高质量铁水的原因.指出,镇江铸造焦是目前国内比较好的、适于冲天炉熔炼用的焦炭.它具有底焦燃烧过程稳定,即炉内温度和CO_2分布曲线右移、高温区位置下移、炉内温度和CO_2浓度达到最大值后下降平缓,加料口CO_2值高、CO值低的特点.因而可以获得高温优质铁水,且经济效益亦高.     

DG220／100-4型锅炉燃烧器损坏的原因分析及治理对策

电站锅炉燃烧器在运行过程中，由于受到锅炉本体设备膨胀的影响，和炉内高温烟气的热辐射，经常造成燃烧器喷口及其与本体设备连接部位发生烧坏泄漏现象。本文对DG220／100-4型锅炉燃烧器的泄漏原因进行了分析，并提出改进措施，经过实施，取得了很好的治理效果。     

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。     

烟气自循环燃气旋流燃烧器结构特性数值研究

烟气自循环是常用的降低NO_x排放的措施,采用数值模拟对自行设计的烟气自循环燃气燃烧器的结构特性进行了研究,着重考察燃烧器结构参数对烟气自循环的影响。结果表明：增加混合管截面积可以提高该燃烧器的引射烟气性能,增加自循环烟气量;混合管扩张角对引射烟气流量比的影响是与混合管尺寸密切相关,在混合管直径较小时,引射烟气流量比呈现出先增加后减小的趋势;在混合管直径较大时,引射烟气流量比持续降低。总之,圆锥混合管的较佳截面比为6.25～9.00,较合适的扩张角为5.7～14.0°。     

富氧(纯氧)燃烧器的研究现状及发展趋势

通过全混流反应器模型,对助燃剂中氧浓度对燃烧平衡状态下产物的成分、温度以及燃料点火特性的影响规律进行了分析,结合国内外学者对燃料富氧燃烧机理的研究提出了燃料富氧燃烧的主要特点。基于分析和计算得到的结论,对目前国内外典型的富氧(纯氧)燃烧器进行归类分析,提出了未来富氧(纯氧)燃烧器的发展和主要研究方向,为富氧(纯氧)燃烧器未来的研究和技术开发提供参考。     

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。     

金属多孔材料表面燃烧器的发展现状

叙述了金属多孔材料表面燃烧器的工作原理及发展现状,重点介绍了这类燃烧器的制作方法、催化燃烧技术、表面稳定燃烧技术、理论研究现状及其应用领域.     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

THERMODYNAMICS STUDY ON THE DECOMPOSITION OF CHROMITE WITH KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

INFLUENCE OF HEAT TREATMENT ON DAMPING BEHAVIOUR OF THE MAGNESIUM WROUGHT ALLOY AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.