多种厚度规格板坯连铸机辊缝偏差探讨

通过对多种厚度规格的板坯连铸机辊缝设计原理的研究,发现因板坯厚度规格多,设计基准辊缝与实际生产辊缝不一致,而存在固有辊缝偏差。研究从辊缝偏差的原理着手,推导出辊缝偏差、包络线偏差的计算方法,并根据实例分析其对凝固界面变形率的影响,提出了减小固有偏差的措施,对实现连铸机辊缝的精确控制具有指导意义。     

保护气氛辊底炉炉辊的改造

为了提高生产能力对带氮气保护气氛辊底式退火炉进行了改造,改造的关键是提高炉辊的承载力。改造采用新型节镍材料3Cr24Ni7SiN替代原来的Cr25Ni20Si2制作辊底退火炉炉辊,介绍了改造的方案以及新炉辊的设计特别是炉辊的壁厚的计算。改造后近2年的运行结果表明,经过改造的退火炉生产能力达到了预期的目的,而且设备运行平稳,产品质量符合标准要求。     

辊底式常化炉非金属水冷炉辊研制及应用

一、前言 辊底式热处理是专门用于钢板、钢管、型钢等退火、正火、回火的热工设备,而且辊底式热处理炉的炉底传送机构采用金属炉辊,为了延长金属炉辊高达1000℃炉温下的使用寿命,故而进行通水冷却,这样造成的后果是浪费了大量的水源,另外更严重是造成了钢件的局部黑印,又要消耗炉内的热能,仅冷却水带走的热量就占供入炉的 20～ 30% ,虽然到目前为止也发展了空腹耐热钢炉辊,但其造价比较昂贵,每根炉辊高达2～ 3万元,甚至达6万元,从而造成了企业成本的成倍增长,且其寿命也只能达到3年左右,就炉辊而言,从目前使用的情况看可归结为耗能大、造价高、寿命短等问题,因此,为了大幅度降低炉辊造价,提高炉辊的使用寿命和提高炉子的有效作业率及热效率,节约耐热钢材,有必要利用目前发展的新技术,开发非金属耐热炉辊。     

磨煤机磨辊裙罩密封改造

古交西山发电有限公司的制粉系统在正常运行期间,磨辊存在进煤粉的情况.针对此项问题进行分析,并对磨辊的裙罩密封进行了改造.经过长时间的运行分析,加装了改造后的密封以后,能有效改善磨辊内部进煤粉的情况,保证磨辊内部的运行环境.实践充分证明,这种密封可以保证磨辊的良好运行.     

有机热载体在四辊压延机上的应用和计算

根据四辊压延机压延辊的加热特点,通过对蒸汽加热及有机热载体加热的分析和计算,说明了用有机热载体对压延辊加热替代蒸汽加热的可行性。     

多线切割机的绕线机构分析

介绍了绕线辊的运行原理,详细分析了多线机绕线辊的结构及布线方式.     

辊底式常化炉非金属水冷炉辊研制及应用

一、前言辊底式热处理炉是专门用于钢板、钢管、型钢等退火、正火、回火的热工设备，而在目前辊底式热处理炉的炉底传送机构均采用金属炉辊，为了延长金属炉辊在高达1000℃炉温下的使用寿命，故而进行通水冷却，这样造成的后果是浪费了大量的水源，另外更严重是造成了钢件的局部黑印，又要消耗炉内的热能，仅冷却水带走的热量就占总供火炉的20一30％，虽然到目前为止也发展了空腹耐热钢炉辊，但其造价比较昂贵，每根炉辊高达2－3万元，甚至达6万元，从而造成了企业成本的成倍增长，且其寿命也只能达到3年左右，就炉辊而言，从目前使用的情况…     

对辊压粉磨的分析探讨

一、前言采用辊压机粉碎水泥生料或熟料的粉碎系统,能够大幅度增产节能,这已被国内外水泥界广泛承认。自1985年西德Leimen水泥厂安装了世界第一台工业辊压机以来,短短几年时间里,国外已出现了上百台辊压机,国内近两年也有好几台辊压机投入运行。脆性物料的辊压粉碎之所以能大幅度增产节能,主要基于西德K.Sehonert教授等人70年代的大量实验研究所提出的高压“料床粉碎”机理。几年来的工业生产数据表     

降低轧辊烧辊的几点改进措施

分析了原轧辊在线材厂多次提速改造后烧辊急剧攀升的原因以及轧辊在装配和结构上存在的局限性,并针对性的在轧辊的轴承密封方面、辊缝调节装置方面实施了一系列的改进措施,从而达到降低烧辊的目的.     

改造旋转接头补偿器节能效益好

我厂1983年底从日本IHI公司引进生产透明硬片的“26×78”倒L型四辊压延机组。 这套压延设备不但各种规格的辊筒多,而且还需加热或冷却才能符合生产工艺要求。全部辊筒共使用了20多只各种型式的     

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%.     

Contents in Volume 23,2014

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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.     

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。     

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.     

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.