N330MW机组振动爬升与碰磨振动的诊断及对策

结合国华准格尔电厂1号机组3号轴瓦频繁出现的间歇性振动问题,对机组的轴系振动进行了在线监测和数据分析,提出了消除机组振动爬升和碰磨振动的技术措施。实施这些技术措施后,现场实验及运行结果表明,本文提出的消除该类机组振动爬升和碰磨振动的技术措施是非常有效的。     

核电汽轮机凝汽器冷却管避免振动碰磨的预防措施

电站汽轮机凝汽器冷却管在机组运行过程中发生振动是不可避免的,文章根据冷却管产生振动碰磨的主要原因,并结合实际工程经验,提出核电机组避免凝汽器冷却管振动碰磨的措施,以降低凝汽器冷却管因振动损坏而造成机组停机的风险,从而提高机组运行的安全可靠性。     

大型汽轮发电机组碰磨故障分析与处理

汽轮发电机组部件动静碰磨是现场最为常见而又非常难以准确诊断的一类故障,由于碰磨故障的不确定性给现场诊断和处理增大了难度.从原因、机理、振动特征和现场处理等方面对动静碰磨作了理论分析,同时通过大量的案例分析,发现在汽轮发电机组中汽轮机发生碰磨故障的概率最高,而对于汽轮机来说低压缸发生碰磨的概率较高,另外分析发现发生碰磨的部位主要集中在机组的油挡和汽封处.同时结合国内660MW机组在升速和空载过程中发生碰磨故障的案例,分析了汽轮发电机组碰磨故障对应的振动特征,现场采用了“磨合”方式进行故障消除,并取得了良好效果,可以为实际机组碰磨故障的现场分析处理提供参考.     

汽轮机汽封碰磨轴振问题的处理措施

某600 MW汽轮机大修并网后发生轴振大的现象,且振动与负荷相关联。根据机组振动曲线,结合大修期间对汽封进行改造的情况,判断振动原因为汽封刷毛与转子间隙不足引发的碰磨。通过采取动静部件充分磨合的方法,相互接触的部分被摩擦掉,并通过在安全区域延长暖机时间的方法,动静部件得以充分膨胀,最终消除了机组因碰磨引起的振动大的问题。研究成果可为同类型机组解决汽封碰磨轴振问题提供参考。     

汽轮机启动过程中振动故障处理与分析

根据芜湖发电厂１２号机组大修后启动过程中的振动故障,分析出振动产生的原因是轴封处的动静碰磨,在采取适当的处理措施后,顺利地解决了振动故障,对振动处理的全过程进行了分析和总结,在并就如何处理汽轮机检修后启动中的动静碰磨提出了一些看法。     

某200MW汽轮机突发性振动故障的分析诊断及处理

针对某200MW机组产生突发异常振动的机理和原因进行了分析,涉及到转子与水接触、轴系标高不合理和动静碰磨等多个因素,提出了处理及预防这种异常振动的方法,对类似振动故障的处理有一定的借鉴价值。     

基于运行参数相关分析的汽轮机组碰磨故障诊断方法及其应用

为快速、精准地确定汽轮机组碰磨故障的原因及位置，提出一种基于机组运行参数相关分析的碰磨故障诊断方法。首先，利用数据预处理方法对汽轮机组的DCS运行数据进行预处理；然后，计算并分析振动参数间、振动与过程参数间的相关性特征，根据相关性特征指标排序法确定碰磨故障原因及发生位置；第三，结合某350MW汽轮机组的碰磨故障实例对所提出的方法进行验证；最后，将诊断结果与皮尔逊相关分析方法诊断结果进行对比分析，结果表明：本文方法可以更好地挖掘出振动参数间、振动与过程参数间的线性、非线性相关性特征，可精准地确定转子碰磨故障原因及位置，能有效指导机组的故障诊断。     

300MW汽轮机端部碰磨振动故障的诊断

某机组在基建调试阶段首次启动过程中,中速暖机1200r／min工况下振动缓慢爬升,15分钟后振动急剧增长,被迫打闸停机。通过试验分析,明确诊断出机组振动故障原因是活动式密封油挡发生碰磨所致。去掉活动式密封油挡后,再次启动完全消除了该机组的振动故障,使机组试运工作得以顺利进行。     

国产引进型300MW机组轴系振动故障诊断

彭城电厂2号机组是改进后的三支承国产化引进型300MW汽轮发电机组（励磁机转子加长300mm)。在调试期间出现了密封瓦碰磨、振动波动、过临界振动大等问题。通过现场处理振动达优良水平。分析了振动现象产生的原因,提出了相应措施,指出了该类型机组存在问题及今后应注意的方面。     

汽轮机组现场动静碰磨故障的振动特征及分析诊断方法

介绍了大型机组现场动静碰磨的机理及发生原因，并结合现场启机和工作转速发生碰磨的实际数据记录，给出了碰磨振动信号特征和诊断方法，可为故障现场分析和诊断提供参考。     

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.