电子束焊接技术在汽轮机隔板制造中的应用

一、概述为了适应大功率汽轮机承担调峰的需要,必须提高汽轮机部件的可靠性。汽轮机隔板在频繁启停和负荷急剧变化的条件下运用,不仅要保证一定的疲劳破坏强度,还必须具备足够的可靠性。由于汽轮机隔板的焊接部位极多,且形状复杂,往往难以确保焊接质量。六十年代以来,随着电子束、等离子、激光、太阳能等新的焊接能源的开发,焊接技术得到了惊人的发展,促进了焊接生产的机械化和自动化,提高了产品的质量。本文介绍电子束焊接技术在汽轮机隔板制造     

电子束焊接在锅炉制造中的某些应用

电子束焊接是近十几年来发展起来的一种新工艺。它首先应用于焊接原子反应堆中的核燃料元件外壳及其他核能部件。目前已发展到应用宇宙航空、电子计算机、汽车制造及仪表业等。在锅炉制造工业中亦已开始应用电子束焊接管子和受压容器。     

汽轮机末级叶片防水蚀

本文对汽轮机末级叶片水蚀防护方法,结合试验和生产实际情况,对国内、外采用的几种方法,进行了介绍和分析;同时,对近年来国外认为先进的电子束焊接叶片和精锻叶片作了评价,指出电子束焊接叶片存在的问题和精锻叶片的优越。根据目前实际情况,认为在大功率汽轮机末级叶片上采用氩弧焊和高频钎焊的方法,焊接硬质合金片保护叶片是可行的;为了简化氩弧焊工艺,提出了以钎焊代替焊后热处理的氩弧焊加钎焊的方法。     

真空电子束深熔透焊接原理浅析

文章详细分析了真空电子束深熔透焊接机理，在电子束焊接能量分配传热模型的基础上，阐明了深熔透焊接的熔池流动行为和熔质密度分布情况，为燃气轮机压气机静叶环真空电子束焊接试验和实际生产提供了强有力的理论依据。     

电子束焊接在燃气轮机生产中的应用

从材料特性及工作环境等方面,指明了电子束焊接相较于其他焊接方法,可以更好地满足燃气轮机焊接零部件的性能需求。同时结合电子束焊接的特点,从耐高温材料的电子束焊接性能、异种钢的电子束焊接、复杂结构的电子束焊接和其他方面的电子束应用4个方面,对国内外在该领域的基础研究和实际应用进行了分析。简述了电子束焊接在各研究方向的发展历程,阐明了电子束焊接在燃气轮机零部件焊接过程中的优势,并提出了各研究方向需要进一步研究的问题。     

超超临界汽轮机低压焊接转子在役检查评估

介绍了上海汽轮机厂生产制造的1 000 MW级火电汽轮机低压焊接转子的基本制造加工情况,其运行服役数据显示振动达到优秀水平。同时对焊缝区域进行了检测评估,结果表明,焊缝区域的硬度、组织正常,各项性能均满足设计要求,转子可以继续稳定服役。研究成果可为汽轮机焊接转子产品在役检查评估提供参考。     

提高汽轮机焊接隔板质量的几点看法

焊接隔板的制造,是汽轮机制造过程中难度较大的环节。多年来,各厂在焊接隔板的制造工艺上都作了很大努力,使焊接隔板的质量有所提高。我厂在焊接隔板制造上,经过多年的摸索、试验,较好地解决了隔板的制造质量问题。焊接隔板精度要求高,工艺过程复杂,尤其是焊接变形较大,质量很难控制。主要件的每一道工序上稍有疏忽,都会影响隔板的制造精度。在我们的长期实践中,在决定焊接隔板质量的主要工序(围带冲孔、围带压弯、叶栅装配和点焊、叶栅焊接、隔板焊接)上作了一些努力,收到了较好的效果。     

国外文献摘要

大功率电子束焊接研究本文着重研究采用大功率电子束焊机对厚壁压力容器进行电子束的焊接工艺。与传统焊接工艺相比,电子束焊接有以下几方面的特点:     

燃气轮机压气机静叶环电子束焊接变形研究

针对燃气轮机压气机静叶环电子束焊接数据进行了收集、整理和分析，得出了影响电子束焊接变形的一般规律，提出了相应的改进措施，实现了焊接变形的量化控制，达到了控制变形的目的。     

核电汽轮机焊接转子技术发展综述

介绍了当前核电汽轮机焊接转子技术发展历程,从转子的锻件材料、坡口设计和工艺方法改进、工艺过程质量控制等方面重点分析了上海汽轮机厂核电焊接转子的工艺技术路线及发展现状。上海汽轮机厂的焊接转子设计、工艺、制造以及检测等技术水平可以保证核电汽轮机的安全运行,该技术代表了当前国际先进水平。     

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。     

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.