圆形铝熔炼炉内非稳态热工过程数值模拟

针对铝熔铸过程中常用的圆形铝熔炼炉,利用FLUENT软件,根据能量守恒方程、动量方程建立铝熔炼炉内热工过程数学模型,采用标准k-ε湍流模型、P-1辐射模型对铝熔炼炉内非稳态传热及流动过程进行数值模拟研究。考虑到铝料熔化过程会消耗一部分能量,采用等效比热法将铝料的熔化潜热转换为相应的比热值进行计算。通过数值模拟得到了炉内流场、炉膛及铝料温度场分布情况。模拟结果与实际情况相符,为铝熔炼炉的设计与优化研究提供了理论依据。     

利用南票劣质煤电厂炉灰生产铝硅铁合金

１前言 铝硅铁合金作为代替纯铝作炼钢的脱氧剂,可以在炼钢过程中提高铝的利用率。南票劣质煤电厂的炉灰中含有品位很高的硅、铝成分,电厂建成后,每年有近４０万ｔ炉灰可做生产铝硅铁合金的原料,加之有充足的电力供应,生产铝硅铁合金,不仅可以减少贮灰场建设投资、减少环境污染,还可以为电厂带来直接的经济效益．生产铝硅铁合金在工艺上是可行的,因此,利用电厂炉灰生产铝硅铁合金从生产技术、原料供应、市场销售等方面均是可行的。２市场分析 铝和硅都是炼钢过程中必须采用的脱氧剂。为了提高在炼钢过程中铝的利用率,我国冶金行业…     

七月上海铝展神秘亮点全新开启《消费电子用铝白皮书》全国首发

正2016中国国际铝工业展览会将于7月12—14日盛大开幕。在保持对铝材深加工、交通及包装用铝关注的同时,还开设了铸件专区、消费电子用铝专区及印度主宾国论坛。首份《消费电子用铝白皮书》也将全国首发。国内首发《消费电子用铝白皮书》,助力铝加工企业转型升级旨在帮助铝加工企业掌握消费电子用铝用户对铝材加工工艺和技术的标准、要求及采购特点,全面梳理     

国内

工信部:公布铝行业准入标准工信部近期发布铝行业准入标准征求意见稿,要求利用国内外铝土矿资源的氧化铝项目起步规模年生产能力应在80万吨及以上;电解铝项目,必须以煤(水)电铝一体化模式或铝电一体化模式建设;鼓励现有电解铝企业通过改造、重组等方式实现煤(水)电铝一体化或铝     

铝离子电池电解液的研究进展

得益于铝负极的高质量/体积能量密度、低成本与高安全性,可充铝离子电池成为极具前景的下一代储能电池体系.铝离子电池主要是基于铝负极、正极材料及1-乙基-3-甲基咪唑氯化物([EMIm]Cl)基的离子液体电解液.目前,储铝正极材料的性能优化已取得了系列进展,但铝离子电池的实际应用受到了[EMIm]Cl基电解液的高成本、腐蚀...     

氟化钾/镍铝复合氧化物的制备及催化合成生物柴油

采用共沉淀、煅烧及研磨的方法制备氟化钾/镍铝复合氧化物,并利用正交实验考察制备条件对氟化钾/镍铝复合氧化物催化合成生物柴油活性的影响,得到优化后的制备条件:镍/铝摩尔比为2、煅烧温度为550℃、煅烧时间为2 h、氟化钾/镍铝复合氧化物质量比为1。以优化条件下制得的氟化钾/镍铝复合氧化物为催化剂,催化蓖麻油与甲醇的酯交换反应,结果蓖麻油转化率为98.9%。采用TG-DTA,FTIR,BET,XRD技术对镍铝水滑石、镍铝复合氧化物及氟化钾/镍铝复合氧化物催化剂进行了表征,结果表明:镍铝水滑石在30~220℃,220~380℃及500~520℃3个温区有3个失重台阶;氟化钾/镍铝复合氧化物催化剂BET表面积为34.42 m2/g,BJH累积孔容为0.128 cm3/g,BJH平均孔半径为5.46 nm;氟化钾/镍铝复合氧化物催化剂由Ni O晶体和K3Al F6晶体构成。     

介绍几种新的铝合金轴承材料

历来,作为内燃机滑动轴承的材料主要是锡基和铅基巴氏合金、磷青铜、锡青铜、铅青铜合金等。国外近年来在改善和发展新的轴承合金材料方面做了大量的试验研究工作,主要对有发展前途的铝基合金轴承材料做了研究和改进。现介绍如下: 一、铝硅镉系改良合金 作为内燃机滑动轴承的合金层,其使用性能优于众所周知的磷青铜、锡青铜、铅青铜、巴氏合金、铝锡系、铝硅系及铝硅镉系合金。 1.铝硅镉锆合金。主要化学成分:Si2     

铝基合金轴承材料的轧制分析及应用

1铝基合金轴承材料简述： 铝基合金轴承材料,一般有”钢背一铝基合金”二层结构（图1．钢背一铝基合金金相图）。铝基合金的厚度一般为0．2—0．5mm,合金材料一般采用高锡、中锡或低锡铝合金,钢背通常采用08或10号钢。     

添加物对钛酸铝性能的影响

本研究采用工业和矿物原料合成钛酸铝,探讨了各种添加物对钛酸铝烧结性能、抗弯强度、热膨胀系数和稳定性的影响,同时利用XRD分析了材料的物相组成。结果表明,添加物的引入能在不提高钛酸铝热膨胀系数的情况下获得具有较高强度的稳定钛酸铝。     

中国能源100问数字解读(五)

<正>(续上期)(54)我国铝锭产量中再生铝占多大比重?2008年铝锭产量1318万t,其中再生铝占21%。再生铝能耗仅为原生铝的3.7%(包括矿石开采、选矿和冶炼)。     

Ash-forming elements in four Scandinavian wood species. Part 1: Summer harvest

Woody biomass in Finland and Sweden comprises mainly four wood species: spruce, pine, birch and aspen. To study the ash, which may cause problems for the combustion device, one tree of each species were cut down and prepared for comparisons with fuel samples. Well-defined samples of wood, bark and foliage were analyzed on 11 ash-forming elements: Si, Al, Fe, Ca, Mg, Mn, Na, K, P, S and Cl. The ash content in the wood tissues (0.2–0.7%) was low compared to the ash content in the bark tissues (1.9–6.4%) and the foliage (2.4–7.7%). The woods’ content of ash-forming elements was consequently low; the highest contents were of Ca (410–1340 ppm) and K (200–1310), followed by Mg (70–290), Mn (15–240) and P (0–350). Present in the wood was also Si (50–190), S (50–200) and Cl (30–110). The bark tissues showed much higher element contents; Ca (4800–19,100 ppm) and K (1600–6400) were the dominating elements, followed by Mg (210–2400), P (210–1200), Mn (110–1100) and S (310–750), but the Cl contents (40–330) were only moderately higher in the bark than in the wood. The young foliage (shoots and deciduous leaves) had the highest K (7100–25,000 ppm), P (1600–5300) and S (1100–2600) contents of all tissues, while the shoots of spruce had the highest Cl contents (820–1360) and its needles the highest Si content (5000–11,300). This paper presented a new approach in fuel characterization: the method excludes the presence of impurities, and focus on different categories of plant tissues. This made it possible to discuss the contents of ash element in a wide spectrum of fuel-types, which are of large importance for the energy production in Finland and Sweden.     

NEXT GENERATION ENGINEERED MATERIALS FOR ULTRA SUPERCRITICAL STEAM TURBINES

正1 ABSTRACT To reduce the effect of global warming on our climate,the levels of CO2emissions should be reduced.One way to do this is to increase the efficiency of electricity production from fossil fuels.This will in turn reduce the amount of CO2emissions for a given power output.Using US practice for efficiency calculations,then a move from a typical US plant running at 37%efficiency to a 760℃/38.5 MPa(1 400/5 580 psi)plant running at 48%efficiency would reduce CO2emissions by 170kg/MW.hr or 25%.     

Aerodynamic performance effects of leading-edge geometry in gas-turbine blades

The purpose of this paper is to illustrate the advantages of the direct surface-curvature distribution blade-design method, originally proposed by Korakianitis, for the leading-edge design of turbine blades, and by extension for other types of airfoil shapes. The leading edge shape is critical in the blade design process, and it is quite difficult to completely control with inverse, semi-inverse or other direct-design methods. The blade-design method is briefly reviewed, and then the effort is concentrated on smoothly blending the leading edge shape (circle or ellipse, etc.) with the main part of the blade surface, in a manner that avoids leading-edge flow-disturbance and flow-separation regions. Specifically in the leading edge region we return to the second-order (parabolic) construction line coupled with a revised smoothing equation between the leading-edge shape and the main part of the blade. The Hodson–Dominy blade has been used as an example to show the ability of this blade-design method to remove leading-edge separation bubbles in gas turbine blades and other airfoil shapes that have very sharp changes in curvature near the leading edge. An additional gas turbine blade example has been used to illustrate the ability of this method to design leading edge shapes that avoid leading-edge separation bubbles at off-design conditions. This gas turbine blade example has inlet flow angle 0°, outlet flow angle −64.3°, and tangential lift coefficient 1.045, in a region of parameters where the leading edge shape is critical for the overall blade performance. Computed results at incidences of −10°,   −5°,   +5°,   +10° are used to illustrate the complete removal of leading edge flow-disturbance regions, thus minimizing the possibility of leading-edge separation bubbles, while concurrently minimizing the stagnation pressure drop from inlet to outlet. These results using two difficult example cases of leading edge geometries illustrate the superiority and utility of this blade-design method when compared with other direct or inverse blade-design methods.     

Hydrogen production by steam-gasification of carbonaceous materials using concentrated solar energy – V. Reactor modeling,optimization, and scale-up

A chemical reactor for the steam-gasification of carbonaceous particles (e.g. coal, coke) is considered for using concentrated solar radiation as the energy source of high-temperature process heat. A two-phase reactor model that couples radiative, convective, and conductive heat transfer to the chemical kinetics is applied to optimize the reactor geometrical configuration and operational parameters (feedstock's initial particle size, feeding rates, and solar power input) for maximum reaction extent and solar-to-chemical energy conversion efficiency of a 5 kW prototype reactor and its scale-up to 300 kW. For the 300 kW reactor, complete reaction extent is predicted for an initial feedstock particle size up to 35 μm at residence times of less than 10 s and peak temperatures of 1818 K, yielding high-quality syngas with a calorific content that has been solar-upgraded by 19% over that of the petcoke gasified.     

Contents in Volume 23,2014

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汽轮机数字电液调节系统挂闸异常的技术完善

分析了200MW汽轮机数字电液调节系统在运行中存在的挂闸异常问题,采取了相应的技术处理措施,且运行实践效果良好。     

新型高压共轨ECU升压模块的数字化开发与优化

为了提高喷油器电磁阀的响应速率,提出了一种基于CPLD(复杂可编程逻辑器件)应用于高压共轨ECU的数字升压模块。鉴于该升压电路结构参数多,其升压电压的恢复响应要求高等特征,基于Pspice建立了升压电路的仿真模型,研究了不同电路参数下升压模块的输出特性,全面优化了该升压模块的性能。结果显示,该升压模块的最大转换效率可以达90%以上。在柴油发动机上对ECU的试验表明,升压电压最大波动不超过10%,其恢复时间仅为1.3ms,功率管最大温升仅为41℃,满足整机运行范围内ECU的需求。     

Assessment methods of material ageing using Sdobyrev''s creep rupture model

The physical aspects of the activation energy, in higher and high temperatures, of the metal creep process were examined. The research results of creep-rupture in a uniaxial stress state and the criterion of creep-rupture in biaxial stress states, at two temperatures, are then presented. For these studies creep-rupture, taking case iron as an example the energy and pseudoenergy activation was determined. For complex stress states the criterion of creep-rupture was taken to be Sdobyrev's, i.e. σ_red = σ₁ β + (1 − β)σ_i, where: σ₁-maximal principal stress, σ_i-stress intensity, β-material constant (at variable temperature β = β(T)). The methods of assessment of the material ageing grade are given in percentages of ageing of new material in the following mechanical properties: 1) creep strength in uniaxial stress state, 2) activation energy in uniaxial stress state, 3) criterion creep strength in complex stress states, 4) activation pseudoenergy in complex stress states. The methods 1) and 3) are the relatively simplest because they result from experimental investigations only at nominal temperature of the structure work, however, for methods 2) and 4) it is necessary to perform the experimental investigations at least at two temperatures.     

Production of hydrogen from sewage biosolids in a continuously fed bioreactor: Effect of hydraulic retention time and sparging

Hydrogen was produced from primary sewage biosolids via mesophilic anaerobic fermentation in a continuously fed bioreactor. Prior to fermentation the sewage biosolids were heated to 70 °C for 1 h to inactivate methanogens and during fermentation a cellulose degrading enzyme was added to improve substrate availability. Hydraulic retention times (HRT) of 18, 24, 36 and 48 h were evaluated for the duration of hydrogen production. Without sparging a hydraulic retention time of 24 h resulted in the longest period of hydrogen production (3 days), during which a hydrogen yield of 21.9 L H₂ kg⁻¹ VS added to the bioreactor was achieved. Methods of preventing the decline of hydrogen production during continuous fermentation were evaluated. Of the techniques evaluated using nitrogen gas to sparge the bioreactor contents proved to be more effective than flushing just the headspace of the bioreactor. Sparging at 0.06 L L min⁻¹ successfully prevented a decline in hydrogen production and resulted in a yield of 27.0  L H₂ kg⁻¹ VS added, over a period of greater than 12 days or 12 HRT. The use of sparging also delayed the build up of acetic acid in the bioreactor, suggesting that it serves to inhibit homoacetogenesis and thus maintain hydrogen production.     

Trace metal chemistry and silicification of microorganisms in geothermal sinter, Taupo Volcanic Zone, New Zealand

As part of a pilot study investigating the role of microorganisms in the immobilisation of As, Sb, B, Tl and Hg, the inorganic geochemistry of seven different active sinter deposits and their contact fluids were characterised. A comprehensive series of sequential extractions for a suite of trace elements was carried out on siliceous sinter and a mixed silica-carbonate sinter. The extractions showed whether metals were loosely exchangeable or bound to carbonate, oxide, organic or crystalline fractions. Hyperthermophilic microbial communities associated with sinters deposited from high temperature (92–94°C) fluids at a variety of geothermal sources were investigated using SEM. The rapidity and style of silicification of the hyperthermophiles can be correlated with the dissolved silica content of the fluid. Although high concentrations of Hg and Tl were found associated with the organic fraction of the sinters, there was no evidence to suggest that any of the heavy metals were associated preferentially with the hyperthermophiles at the high temperature (92–94°C) ends of the terrestrial thermal spring ecosystems studied.