膜法富氧局部助燃技术在煤粉锅炉上的应用

利用膜法富氧技术,在150 t/h煤粉锅炉上进行了局部增氧助燃技术的工业试验.实验表明:膜法富氧局部增氧助燃技术的应用,有效地解决了炉膛结焦和高温腐蚀问题;大渣及飞灰可燃物含量降低,提高了低负荷不投油稳燃能力;提高了锅炉热效率;降低了NOx排放量.     

膜法富氧局部助燃技术在煤粉锅炉上的应用研究

针对150 t/h煤粉动力锅炉,利用膜法富氧技术,首次进行了局部增氧助燃技术应用于煤粉锅炉的工业试验.实践证明,膜法富氧局部增氧助燃技术有效地解决了炉膛结渣和高温腐蚀问题,大渣及飞灰可燃物含量降低,提高了锅炉热效率,降低了NOx排放浓度,提高了低负荷不投油稳燃能力,为煤粉锅炉的安全、经济、低NOx排放开辟了一个新方向.     

应用膜法富氧助燃技术对35t/h抛煤机锅炉进行改造

分析了抛煤机锅炉存在的缺点及产生这些缺点的原因，介绍了膜法富氧技术以及应用膜法富氧助燃技术对35t/h抛煤机锅炉进行改造的方案。     

自动可调叶栅煤粉分配器的应用研究

介绍了一种新型自动可调式煤粉分配装置,重点说明了它的稳燃原理及其在风扇磨煤机直吹式制粉系统中的应用情况。通过大量的工业试验,对自动可调式煤粉分配器的风量,煤粉量的调整特性进行了研究。结果表明;新型自动可调叶栅煤粉分配器应用于国产670t/h褐煤锅炉中,能在运行中对空气和煤粉分配进行调节,实现了风粉分配由不可控制到有效控制,使锅炉的低负荷不投油稳燃能力由原来70%降低到45%。达到了大幅度降负荷运行的目的,并且由于燃料在炉内燃烧被分为过浓燃烧和过淡燃烧两部分,使NOx排放量低于469mg/m^3,机械不完全燃烧损失降低了1.958%。有效地提高了锅炉机组的热效率和低负荷运行的能力。图9表3参2     

双稳可调浓淡煤粉燃烧技术在410t/h锅炉上的应用

焦作丹河发电有限责任公司2号煤粉炉是410t/h四角喷燃高压煤粉锅炉。1999年5月应用双稳可调浓淡煤粉燃烧技术对中、下层燃烧器进行改造，改造后运行情况良好，低负荷锅炉效率从89.92%提高到91.15%；在40％－50％负荷下不投助燃油能稳定燃烧；煤种适应性较广泛，锅炉运行安全性和经济性都有所提高。     

YG65╱3.82-M_1型锅炉节能技术改造

YG65/3.82-M_1型锅炉热效率低,低负荷稳燃能力差。采用STF-Ⅲ型双通道煤粉燃烧器改进后,锅炉启动速度快,锅炉热效率提高4.612～5.276％,煤粉粒子燃尽率提高3.270％～3.919％,燃烧器着火燃烧稳定性好。煤种适应性强,最低稳燃负荷为53.33％。     

水平浓谈风煤粉燃烧器低负荷稳燃性能的试验研究

通过水平浓淡风煤粉燃烧器气固混合特性的试验研究及在320MW双炉膛锅炉上的应用表明：该燃烧器具有较强的低负荷稳燃能力，同时具有燃烧效率高，防结渣及防水冷壁高温腐蚀性能。在减少电厂低负荷稳燃用油方面经济效益显著。图8参4     

防水冷壁高温腐蚀的煤粉燃烧技术及工业性试验研究

通过对大型电站四角切圆煤粉燃烧锅炉水冷壁高温腐蚀原因的分析,从燃烧的角度提出了水平浓淡分离、单喷嘴分级燃烧,以及通过一次风射流生而改善炉内燃烧两相流场,从而解决高温腐蚀的煤粉燃烧技术。结合在大型煤粉炉上的工业性试验研究,证明了水平浓淡工粉燃烧器具有较强的防水冷壁高温腐蚀及高效、低负荷稳燃、防结渣和低ＮＯｘ排放的性能。     

水平浓淡风煤粉燃烧器低负荷稳燃性能的试验研究

通过水平浓淡风煤粉燃烧器气固混合特性的试验研究及在 3 2 0 MW双炉膛锅炉上的应用表明 :该燃烧器具有较强的低负荷稳燃能力 ,同时具有燃烧效率高 ,防结渣及防水冷壁高温腐蚀性能。在减少电厂低负荷稳燃用油方面经济效益显著。图 8参 4     

煤粉稳燃技术的发展历程和展望

上世纪80年代以来在国内应用的煤粉稳燃技术可分为2种主要类型:早期以强化回流为主要技术特征的第一代稳燃技术,和后来以浓淡分离为主要技术特征的第二代稳燃技术.系统地介绍了这2类技术的发展历程.分析了煤粉稳燃技术在解决燃烧经济性、低污染排放、煤种和负荷适应性、防结渣腐蚀等各方面问题中的基础性地位,强调了目前仍需大力研发新型煤粉稳燃技术.提出了煤粉稳燃技术的发展目标:既具有优良的稳燃、燃尽、低污染物排放、防结渣和腐蚀性能,又能够自动适应煤种、负荷大范围的变化,保持锅炉运行良好的性能.     

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.