某工业型燃气轮机起动电机系统故障分析

某工业型燃气轮机常出现起动电机系统故障,起动电机系统故障直接导致燃气轮机起动失败。本文针对该型燃气轮机起动电机系统故障问题,从起动电机工作原理出发,并结合燃气轮机运行工作中出现的典型故障进行分析,为该型燃气轮机起动电机系统故障的排查指明了方向。     

燃气轮机起动失败的故障分析及检查方法

燃气轮机起动性能的好坏直接影响到其应急起动能力，甚至到机组能否正常投运。该文总结了ＭＳ６００１型气轮机多年的起动及运行经验，列举了一些燃气轮机起动失败的故障类型，并对故障进行了分析，提出了检查处理方法。     

某型船用燃气轮机起动过程故障分析

某型船用燃气轮机由冷态起动至慢车工况,经历电机起动、空气压缩、点火燃烧、涡轮升速等过程。起动过程由静态到动态,由电能和燃油的化学能转化为涡轮的机械能,是一个发生急剧物理化学变化的过程,同时也是发动机最容易发生故障的过程。在分析该型燃气轮机起动过程特点的基础上,重点分析了起动过程中可能产生的故障类型和原因。通过典型故障分析,提出了实际操纵运行中的注意事项和建议。     

某工业型燃气轮机超温停机故障分析

某工业型燃气轮机出现过多次超温停机故障，主要分为起动过程超温停机故障和工况运行超温停机 故障。针对该型燃气轮机超温停机故障问题，从燃气超温停机控制原理出发，并结合燃气轮机运行工作中出 现的典型故障进行分析，总结出了适用于该型燃气轮机超温停机故障分析方法，对燃气轮机的稳定运行具有 重要意义。     

燃气轮机起动过程中点火失败的原因及处理方法

本文叙述了燃气轮机起动过程中点火失败的主要原因,并对燃油旁通伺服阀和点火装置的故障检查方法作了具体说明,以供同行参考。     

某型燃气轮机起动过程中火焰缺失 故障分析与处理

通过对某电站燃气轮机在起动时出现火焰缺失跳机故障检查研究，分析发现起动设备对燃气轮机发 出起动指令后有延迟响应时间。现场测试了起动电机响应时间、液力变扭器卸荷阀动作响应时间，发现响应 时间有延迟会引起燃料控制量自动增加以保证燃气轮机升速。重新设定了燃气轮机起动和暖机阶段燃料设 定值后解决了该故障。该燃气轮机火焰缺失故障检查和处理过程可为今后故障的处理提供参考。     

燃气轮机可靠性运行维护策略研究

对某型燃气轮机长时间运行过程中出现的各类故障进行归纳并进行故障影响分析。从燃气轮机运行原理及故障特点出发,提出了该型机组的可靠性维护策略,包括故障排查方法研究,该策略及方法可以在故障发生时高效排除故障;对易出现故障的部件,采取改进结构、升级控制逻辑等一系列措施,提高运行可靠性,降低故障率。研究成果对燃气轮机稳定运行具有建设性意义。     

某型燃气轮机高工况突发停机故障分析研究

对某型燃气轮机实际运行过程中出现的高工况突发停机故障案例进行分析,从燃气轮机运行原理及控制原理出发,总结出了故障处置方案。对可能造成燃气轮机高工况停机的方面进行分析,提出了运行维护相关事项,对燃气轮机预防故障发生、维护可靠稳定运行具有建设性意义。     

某工业型燃气轮机启动悬挂故障分析

某工业型燃气轮机在启动过程中,发生多次悬挂故障。对该型燃气轮机实际运行过程中出现的典型启动悬挂故障进行分析及归纳,给出了该型燃气轮机启动悬挂故障的处理措施,提出通过燃油预调节措施可预防悬挂故障的发生。研究成果可为燃气轮机安全稳定运行提供技术参考与借鉴。     

某型燃气轮机运行突发故障分析

对近100台某型燃气轮机实际运行过程中出现的各类突发故障案例进行归纳,从燃气轮机运行原理、控制原理出发,对运行中各突发故障的原因进行分析,总结出了故障排查方案。针对各类突发故障,提出燃气轮机运行注意事项。研究成果对燃气轮机稳定运行具有重要意义。     

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.