煤粉锅炉制粉系统的改进——制粉系统交叉管

煤粉锅炉的制粉系统通常都是两套(每套包括磨煤机、排粉机各一台),正常情况下,两套制粉系统独立运行,各向一个粉仓送粉。如果其中一套制粉系统因故障检修时,要使机组负荷不减,必须启动绞笼向检修侧粉仓送粉。众所周知,绞笼不适于长时间连续运行,否则常会发生烧孔和绞笼断裂故障,从而无法维持锅炉运行,以至停炉。此外,由于制粉系统的设计出力无法得到合     

600MW亚临界机组锅炉设备优化改造

介绍伊敏发电厂在燃煤机组锅炉制粉系统、干排渣技术应用、以及系统优化设计方面进行的技改工作,取得了较好的效果。     

炉烟干燥开式制粉系统的锅炉热平衡及烟气特性计算方法

在当前国内的锅炉相关标准及文献中,均未对炉烟干燥开式制粉系统锅炉的热平衡及热力计算方法予以介绍。本研究提出了开式制粉系统的3种炉烟干燥方案,并对应用这3种炉烟干燥方案的开式制粉系统锅炉的热平衡及烟气特性进行了深入分析,指出了其与传统闭式制粉系统锅炉的区别。继而,基于常规的燃煤收到基分析数据及低位发热量,提出了适用于炉烟干燥开式制粉系统锅炉的热平衡及烟气特性计算方法,据此可完成完整的开式制粉系统锅炉热力计算。该计算方法为炉烟干燥开式制粉系统锅炉的研究、应用及优化提供了理论基础。     

煤粉锅炉制粉系统运行分析及优化方法研究

因煤种变化等原因,扬子热电厂锅炉的磨煤单耗逐渐上升。为了找到最佳的运行工况,降低磨煤单耗,对1号锅炉制粉系统的出力情况进行了分析研究。通过对扬子石化热电厂1号锅炉甲侧制粉系统的运行进行分析,认为在现有煤种情况下降低磨煤单耗是可行的。并通过调整试验和数据统计,找到了运行中影响制粉系统出力的瓶颈问题,通过调整制粉系统的运行方式,优化运行参数,在保证锅炉燃烧效率的前提下,提高了制粉系统的出力,降低了磨煤单耗,提高了锅炉制粉系统运行的经济性。     

大型钢球磨煤机直吹式制粉系统提高出力的实践

介绍600MW机组锅炉为提高制粉系统出力而进行的制粉系统改造,包括制粉系统分离器改造和磨煤机改造;介绍对制粉系统运行参数进行的调整,以及制粉系统出力试验,并对制粉系统出力试验的结果进行分析,指出影响制粉系统出力的几个主要因素。通过制粉系统改造前后的出力对比试验,证明所采取的措施能显著增加制粉系统出力,使制粉系统出力从40t/h增加到约60t/h,提高了锅炉的安全经济运行水平。     

130t／h煤粉炉燃用易结焦煤的防结焦改造

煤粉锅炉的燃烧系统、制粉系统的设计与锅炉燃料特性关系紧密,若二者不相匹配,则实际运行中会出现制粉出力不足、锅炉燃烧不好及结焦等状况,严重影响机组的安全经济运行。本文结合本溪北钢集团北营发电公司3#炉改用易结焦煤而改造其燃烧系统、制粉系统,以达到锅炉防结焦实例,对锅炉燃烧、制粉系统的设计与锅炉燃料特性的匹配进行论述。     

电站锅炉直吹式制粉系统的节能实践

针对珠啤热电厂锅炉制粉系统进行的改造和调整试验,对制约制粉系统经济性的因素进行了分析,并提出了改进措施,可为配有E型中速磨煤机直吹式制粉系统的电站锅炉经济运行提供参考。     

中速磨煤机直吹式制粉系统特性对锅炉运行的影响分析

根据中速磨煤机直吹式制粉系统设计及运行参数的特性,分析了磨煤机的风量、煤粉分配均匀性、磨煤机负荷率、煤粉细度、煤质变化等因素对大型煤粉锅炉燃烧系统的影响。在锅炉运行中,需根据制粉系统的特性优化调整锅炉的运行参数,达到制粉系统与锅炉燃烧系统的耦合匹配。     

直吹式制粉系统与空气预热器的质量能量平衡关系分析

1前言在现代煤粉锅炉中,制粉系统是锅炉设备最重要的辅助系统之一。直吹式制粉系统与锅炉设备的联系尤为密切,直吹式制粉系统的运行条件不但影响进入锅炉炉膛的热量大小和燃料进入炉膛的着火燃烧条件,而且还会影响流经空气预热器的空气量和出口热空气温度,导致空气预热器在尾部     

锦化热电厂冷却水节水改造

１前言锦化化工（集团）有限责任公司热电厂装机总容量２４ＭＷ，１３０ｔ／ｈ立式旋风炉两台，制粉系统ＤＴＭ２５Ｗ３９０球磨机四台，Ｍｇ—２６ＮＯ．１３排粉机四台，锅炉取样的冷却水年用水量ｍ．８８万ｔ。这两台炉１９８９年１０月投产，由于当时节能意识不强，设计计算不合理，使这部分水一直排入渣池，作为冲渣粒化的补充水。到改造时已排掉好水１２２．６４万ｔ，冲渣、粒化的水是闭式循环，不需这么大的补水量，这样就浪费了大量的好水，为节约水资源，于１９９６年对原来的冷却水系统进行了改造，使这部分水得以重复使用。２冷…     

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。     

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.