高参数大容量电站锅炉过热器再热器的超温问题和炉内壁温在线监测

针对我国超临界和亚临界大容量锅炉过热器再热器的超温爆管及管内氧化垢事故,用电厂实例综述了发生这些事故在运行和设计两方面的因素,指出在运行中减小过热器再热器管组沿宽度的温度偏差是避免这种事故的重要手段.采用具有精度高而且功能齐全的管子炉内壁温在线监测系统可以实现锅炉的实时小偏差运行,减少氧化垢的生成并延长高温管屏的使用寿命.     

330MW机组末级过热器异物堵塞及泄漏失效分析

某火力热电厂330 MW机组2号锅炉末级过热器因异物堵塞导致泄漏事故,对2号锅炉末级过热器泄漏管样、末级过热器吹漏管样进行了宏观检查、化学成分、室温力学性能、显微组织、显微硬度、氧化皮厚度、垢量及垢样成分等项目的试验与分析,针对试验分析结果对泄漏原因进行了综合分析,结果表明此次泄漏事故原因为异物堵塞导致管样长时超温。     

新疆某电厂3号炉水冷壁泄露原因分析

通过对某电厂#3炉泄露的右水冷壁管子取样进行试验分析,确定水冷壁管子的泄露原因以及水冷壁泄露的影响因素,对于电厂日常运行有一定指导意义。     

某热电厂锅炉过热器管爆管原因分析

通过宏观检查、化学成分分析、金相分析、硬度试验和扫描电镜分析等分析方法,对锅炉过热器管爆管原因进行了分析,结果表明:管子存在严重超温运行情况,导致管子完全脱碳强度降低,同时导致管子过热,加重了内表面氧化和外表面烟气腐蚀情况。内表面氧化和外表面烟气腐蚀同时作用使管子壁厚严重减薄,管子因承压能力不足最终爆管。     

DZL4-13型锅炉水冷壁管爆裂原因分析

某锅炉水冷壁管在运行过程中发生爆管 ,通过宏观、微观金相检验和X射线物相分析等检测方法 ,对其进行了分析。结果表明 ,爆管系水质管理不当而产生严重水垢 ,使水冷壁管局部长期超温 ,显微组织珠光体球化 ,引起管子蠕变胀粗而最终爆管     

印尼某循环流化床锅炉屏式过热器爆管原因分析及解决措施

印尼某电厂2~#循环流化床(CFB)锅炉屏式过热器短时间内发生3次类似的爆管,爆管管样的化学成分分析、金相检测及力学性能等测试结果表明,爆管是由超温引起的。经过检查和分析,认为屏过管子、集箱内的异物堵塞,以及启动初期减温水投入不当引起水塞是屏过超温爆管的原因,采用管道清洗、控制减温水投入量等措施,锅炉屏过爆管问题得到有效遏制。     

新建150t／h循环流化床锅炉高温过热器管开裂原因分析

某热力公司新建150t／h循环流化床锅炉运行月余，其高温过热器管发生大范围开裂泄露。通过对开裂管子取样进行机械性能、金相组织、扫描电镜和能谱测试等试验，对裂纹的形成和扩展原因进行分析。经分析认为，锅炉在煮炉过程中，碱液进入过热器管道，运行中碱液浓缩聚集引起焊缝及弯头部位应力腐蚀造成开裂。     

姚孟电厂1000吨/时直流锅炉炉膛水冷壁管横向裂纹原因分析及改进措施

姚孟电厂两台配30万千瓦发电机组的直流锅炉因炉膛水冷壁爆管、泄漏引起的停炉次数约占锅炉事故停机次数的二分之一,水冷壁多为横向裂纹爆管。通过对炉膛水冷壁管的壁温测量、爆管处金相分析,以及燃烧工况、给水和喷水等试验测量,说明发生水冷壁管横向裂纹的原因主要是低负荷时给水量过分小于相应负荷所需的给水量、中辐射区管屏两侧联箱端头的管子引出方式不合理、炉内燃烧工况组织不良等。本文最后提出了消除水冷壁管横向裂纹泄漏的措施。     

某电厂660MW超超临界锅炉螺旋水冷壁超温事故分析

某超超临界锅炉启动初期螺旋管水冷壁超温。割管检查,发现超温管子焊缝内壁存在焊瘤,焊瘤的节流作用使管子内介质流量减少,导致管子超温停炉。     

对一台2.8MW锅壳式燃气热水锅炉漏水的浅析

本文通过对一台燃气热水锅炉的管板与管子连接处的漏水进行检查、分析，引起漏水的主要原因，一是给水不符合国标所要求的水质，其二是管板与管子连接处的水流动速度低，材料的壁温超温，强度下降。对以上存在的问题进行全面分析，提出了解决的方法。     

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.     

Wind power for pumping: The development of the ITP windpump

Water pumping has been one of the main applications for wind power in the past and despite the spread of mains-electric pumps, more than a million windpumps remain in regular use. This paper reviews the general technical and economic requirements for pumping water using wind energy and by way of example gives an overview of the development of the new ITP wind-pump. It then considers the future prospects for this kind of technology.     

Methods of creating solar-reflective nonwhite surfaces and their application to residential roofing materials

We describe methods for creating solar-reflective nonwhite surfaces and their application to a wide variety of residential roofing materials, including metal, clay tile, concrete tile, wood, and asphalt shingle. Reflectance in the near-infrared (NIR) spectrum (0.7–2.5 μm) is maximized by coloring a topcoat with pigments that weakly absorb and (optionally) strongly backscatter NIR radiation, and by adding an NIR-reflective basecoat (e.g., one colored with titanium dioxide rutile white) if both the topcoat and the substrate weakly reflect NIR radiation. Coated steel and glazed clay-tile roofing products achieved NIR reflectances of up to 0.50 and 0.75, respectively, using only cool topcoats. Gray-cement concrete tiles achieved NIR reflectances as high as 0.60 with coatings colored by NIR-scattering pigments. Such tiles could attain NIR reflectances of up to 0.85 by overlaying a white basecoat with a topcoat colored by NIR-transparent organic pigments. Granule-surfaced asphalt shingles achieved NIR reflectances as high as 0.45 when the granules were covered with a white basecoat and a cool color topcoat.     

Thermal decay of an initially hot isothermal water body with application to thermal energy storage

The thermal decay of an initially hot isothermal water body contained in a tank was studied. Analytical solutions (including a group-theoretic solution) were obtained for the one-dimensional heat conduction equation with heat loss from the sides of the tank. The convective heat transfer coefficient was assumed not to be constant over the surface of the tank but to vary with space and time. A very good agreement was obtained between the group-theoretic solution and a numerical solution using the Crank-Nicholson finite difference scheme. The analytical results are discussed in terms of the underlying physical mechanisms.     

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.     

秸秆燃烧中温度对钾转化与释放的影响

通过对稻秆原料进行常规特性分析和EDX元素含量分析,发现钾在稻秆无机元素中占有重要地位。参考原料化学分馏法和土壤中钾的分类与测试方法,给出了对生物质原料及其燃烧产物中钾的定性与定量简易方法。通过程序控温型固定床对稻秆先进行缓慢氧化,然后以100℃为间隔从400～900℃进行成灰,并分别测试其成灰率、有效钾和全钾的份额。结合稻秆原料及其灰中钾的份额分析,进行了稻秆灰中有效钾转化与释放的计算,发现有效钾在700～800℃之间有快速的释放和形态转变。稻秆灰的XRD分析结果表明秸秆灰中钾主要以KCl、K_2SO_4形式存在,得到了钾以盐的形式进行转化与释放的机理。该文中燃烧温度对钾转化与释放的影响规律对设计秸秆电厂时的炉型选择和燃烧参数确定有一定参考价值。