600MW汽轮机不同负荷下高压缸法兰螺栓密封应力分析

以600MW汽轮机高压缸为例进行不同负荷下高压缸法兰螺栓密封应力分析，给出了高压内缸和外缸压差随机组功率变化曲线，进一步给出了法兰螺栓所需密封应力随机组功率变化曲线，为延长机组连续运行时间、增长大修周期时间和法兰螺栓剩余寿命在线监测提供理论依据。     

电站汽轮机高压内缸的二维在线计算方法

以某引进的125 MW汽轮机内缸为研究对象,建立二维非稳态的汽缸热应力的计算模型,并用三维有限元计算结果进行了修正,得到了二维应力修正系数,其精度基本达到了工程计算的要求.采用二维模型对汽轮机的实际起停过程中高压内缸的热应力进行了在线计算,得到了起停阶段和稳定运行时影响汽缸热应力的各种因素,揭示了该型汽轮机高压内缸出现内张口的原因,并提出了合理的运行建议.二维汽缸的在线计算模型同样适合其它类型的汽轮发电机组.     

超临界汽轮机红套环高压内缸开裂的强度有限元分析及运行对策

介绍了某型号超临界汽轮机红套环高压内缸强度有限元分析方法,对红套环高压内缸额定负荷稳态工况以及冷态启动、温态启动、热态启动和极热态启动等瞬态工况进行了强度计算与分析,得出了红套环高压内缸额定负荷稳态工况和瞬态工况下的温度场分布和最大应力比,并提出了该汽轮机的优化运行措施.结果表明:红套环高压内缸开裂部位瞬态工况下的应力过大是产生裂纹的主要原因之一;推荐的优化运行措施包括该汽轮机应多带基本负荷,减少机组启停次数,降低启动过程中负荷在29%~56%内主蒸汽的升温率,特别应降低负荷在53%~56%内主蒸汽的升温率.     

冷态起动升负荷阶段法兰加热对法兰温度场和膨胀量的影响

本文介绍了东汽二十万千瓦汽轮机高压缸法兰在起动带低负荷过程中的温度场计算工作和计算结果,对有法兰加热与无法兰情况下的温度分布和汽缸法兰的膨胀量作了分     

汽轮机红套环筒形高压内缸设计制造与检修的技术研究

介绍了汽轮机红套环筒形高压内缸的设计、制造与检修的几项关键技术,包括红套环筒形高压内缸的常规设计方法、有限元分析设计方法、实际过盈量的制造过程保障方法和红套紧力的检修监控方法。提出了红套环筒形高压内缸额定负荷稳态工况和起动与停机瞬态工况下的强度设计方法、额定负荷稳态工况下的蠕变设计方法和起动与停机瞬态工况下高压内缸中分面严密性的设计方法,给出了某电厂600 MW超临界汽轮机筒形高压内缸的红套环设计数据,以及高压内缸制造与检修过程增加垫片厚度的应用实例,并分析了高压内缸开裂的原因。结果表明:合理增加红套环与高压内缸间的垫片厚度,既可以保证红套环与高压内缸首次装配的实际过盈量达到设计要求,又可以保证红套环的红套紧力与高压内缸的严密性处于受控状态。     

核电汽轮机高压缸法兰结合面接触分析

大型核电汽轮机高压缸尺寸大、结构复杂,运行中多种因素可能导致其受力不均,进而影响汽缸法兰结合面接触状态。以某大型核电汽轮机高压缸为研究对象,建立其三维模型,并用ANSYS/WORKBENCH计算分析了稳态运行时汽缸轴封处温度分布与螺栓预紧力对法兰结合面接触状态的影响。计算结果表明,在给定条件下,螺栓的预紧扭矩为6800N·m、高压缸轴封处沿轴向的温度梯度不高于30℃/m时,法兰结合面接触状态良好;螺栓的预紧扭矩为9200N·m、高压缸轴封处沿轴向的温度梯度不高于40℃/m时,法兰结合面接触状态良好;螺栓的预紧扭矩为12 000N·m、高压缸轴封处沿轴向的温度梯度不高于50℃/m时,法兰结合面接触状态良好。     

1000MW核电汽轮机高压缸启动过程热应力及汽密性分析

汽轮机高压缸是高温高压蒸汽的通流部件,其内壁面直接和蒸汽接触。在机组启停及变负荷时,蒸汽参数的剧烈变化容易造成高压缸热应力过大甚至变形等现象。以某型1 000 MW核电半速汽轮机高压缸为例,对其启动过程高压缸的温度及应力分布进行有限元计算,进而分析汽缸中分面的汽密性。计算结果表明:在所设置的启动曲线下,启动过程中,高压缸轴封处温差及应力均较大,且中分面接触压力较小;高压缸最大热应力(217 MPa)出现在机组刚进入额定负荷时刻。     

核电汽轮机高压缸三维有限元热应力分析

在变工况时，核电汽轮机的汽缸表面温度随蒸汽温度快速变化，引起汽缸内部大的温差与热应力；在稳态条件下，汽缸大压差截面处也存在大的温差与热应力。文中着重介绍核电汽轮机高压缸的热应力计算和分析，考虑了中分面的密封分析，计算了冷态起动，加负荷、稳态和甩负荷过程中的瞬态非线性温度场，然后以材料非线性模式求解相应的热应力场。     

法兰螺栓加热装置对汽轮机高压缸胀差的影响

主要探讨200MW汽轮机组法兰螺栓加热装置对高压缸胀差的影响。通过对现场运行数据的分析和对法兰螺栓加热装置的详细研究,得出引起高压缸胀差异常的原因。法兰螺栓加热装置的设计是为了控制机组启停过程中的胀差,但若加热装置本身出现问题,也就必然会对机组的膨胀产生不利影响。     

核电汽轮机高压汽缸热应力分析

对核电汽轮机高压汽缸冷态启动,加负荷、甩负荷等情况下的热应力,包括各种工况下的传热情况,缸壁应力及中分面螺栓应力进行了讨论。计算结果说明:核电汽轮机在启停与变负荷时汽缸的热应力不大,最大应力只发生在稳态全负荷,并可通过合理的结构设计来解决。     

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.     

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.     

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。     

Contents in Volume 23,2014

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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.