国产300 MW三分仓容克式空气预热器改造

对空气预热器漏风的机理及国产三分仓容克式空气预热器漏风大的原因进行了分析.以上海石洞口电厂空气预热器改造为例,详细介绍了该厂1号机组空气预热器的改造方案与改造成果.总结介绍了随后几年陆续进行的3台机组空气预热器的改造实施效果.     

国华太仓发电有限公司2×600 MW机组空气预热器对SCR系统的适应性改造

介绍了针对600 MW锅炉机组加装SCR系统的空气预热器改造过程,提供了改造前后的空气预热器对比性能参数,对改造过程中所遇到的问题进行了分析并提出了解决方案.通过改造发现,加装SCR会导致空气预热器入口烟气温度下降,影响空气预热器的换热量.空气预热器通过增加部分换热面能改善空气预热器的换热情况.对氨气逃逸率控制良好的锅炉,空气预热器堵灰程度和阻力上升均很轻微.对磨煤机进口要求温度较高的运行情况,改变空气预热器的转向为先加热一次风,能明显提高一次风出口温度,保证制粉系统在锅炉低负荷时的灵活条件需要.     

回转式空气预热器漏风处理及实例

本文对回转式空气预热器漏风问题进行了研究和分析,得出直接漏风是空气预热器漏风的主要因素。并从直接漏风根本原因出发,介绍了空气预热器漏风常见问题及处理方法,在此基础上,结合某电厂回转式空气预热器改造实例,说明了采取正确措施减小回转式空气预热器漏风,对电厂经济性、安全性具有重大意义。     

600 MW机组空气预热器改造

针对600MW机组空气预热器入口烟温低、积灰燃损、漏风率大等问题,对空气预热器结构进行了改进,并采取一系列措施对空气预热器进行了改造,提高了系统的经济性和运行安全性。     

50286型锅炉空气预热器的改造

使用管式空气预热器产生一系列的问题 ,采用螺旋槽管式空气预热器是一种有效的改造措施。文中针对管式空气预热器的检修空间不足的情况 ,介绍了改为螺旋槽管空气预热器的方案及其实例     

大型电站锅炉空气预热器应用热管的探讨

本文根据黄埔电厂3号炉空气预热器改造前、后的实际情况进行对比分析,讨论应用热管应注意的问题。     

基于循环风的空气预热器防堵技术研究

随着环保要求的日益严格,电厂锅炉通常进行脱硝系统改造来控制NOx排放,导致回转式空气预热器普遍存在堵灰现象,严重影响机组运行经济性和安全性。为了解决该实际问题,本文首先分析了空气预热器的堵灰机理。然后从堵灰机理出发,提出了基于循环风的空气预热器防堵灰技术。结合某电厂的实际情况,进行了基于循环风的防堵灰改造,改造内容主要包括设备改造和控制系统改造。然后通过对技术改造前后的效益分析表明:该技术不仅能提高机组运行安全性,而且在运行经济性上提高了空气预热器和锅炉的效率,为电厂运行带来较大的经济收益。因此本文提出的基于循环风防堵灰技术在实际应用中能有效解决空气预热器堵灰问题,保证机组安全经济性运行。     

配SCR的锅炉空气预热器适应性改造实践

宝钢电厂1、2号350 MW机组锅炉因环保需要增设的烟气脱硝装置(简称SCR)所产生的硫酸氢氨,将引发空气预热器的腐蚀和堵灰现象,从而严重影响锅炉机组的安全运行,因此必须对空气预热器进行适应性改造。对空气预热器适应脱硝改造的设计原则和技术注意事项进行了研究。改造后锅炉排烟温度下降了5~8℃,平均漏风率降低了1%~2%。烟气流动阻力基本维持在800 Pa以下,且未出现明显的积灰堵塞情况。该项目改造取得了预期目标,为行业提供了成功的案例经验。     

660MW超临界煤粉锅炉空气预热器堵灰及解决措施分析

以DY发电厂新建工程2×660MW机组为例,分析了锅炉空气预热器堵灰的原因。通过SCR优化调整、一、二次风加装暖风器和空气预热器受热面改造解决了空气预热器堵灰,提高了机组带负荷能力。此外,加装暖风器、空气预热器改造造成排烟温度升高影响机组经济性,通过加装低温省煤器进行烟气余热利用,提高机组经济性,保证空气预热器不堵灰正常运行。为我国火电厂空气预热器堵灰问题提供了一种解决办法。     

蒸汽—空气预热器在垃圾焚烧炉的应用及设计分析

结合多个生活垃圾焚烧炉项目出现的运行问题和改造经验,分析了常见蒸汽式空气预热器系统的特点,提出蒸汽—空气预热器的设计原则,确保蒸汽—空气预热器出口风温稳定达标,并对空气预热系统的设计提出建议,为运营项目中的空气预热系统分析提供借鉴。     

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。     

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.