600MW火电机组低负荷调峰的经济运行方式分析

随着电网峰谷差的日益增大,600MW火电机组调峰是其必然趋势。提高调峰机组低负荷运行的经济性,是目前亟待解决的问题。从最优化的角度出发,对600MW汽轮机低负荷调峰运行中火电机组之间负荷的优化分配、汽轮机循环水系统运行方式的优化和配汽方式的优化方法进行分析,给出了通过改变运行方式指导调峰机组低负荷经济运行的具体方法。     

基于遗传算法的多机型多热源复杂热电负荷优化分配方法

热电联产机组因同时能生产热负荷和电负荷而得到了广泛应用.机组在不同热、电负荷下的热耗不同,不同机组在相同热、电负荷下的热耗也不相同.因此,为达到节约能源的目的 ,对其进行热电负荷优化分配成为至关重要的问题.针对某电厂的多机型、多热源的复杂机组,提出了一种改进的遗传算法,对该机组进行负荷优化分配.结果 表明,优化后的热耗...     

多机组、多元化供热模式下厂级热电负荷运行优化策略研究

开展热电联产电厂负荷优化分配研究,可进一步提高能源利用效率。为获得更好的热电负荷分配效果,首先提出了一种布谷鸟搜索-灰狼融合算法,并基于文献中的测试电厂数据验证了该算法的可靠性。然后,以呼和浩特市4机组热电厂为例,建立了多机组厂级热电负荷优化模型。基于该厂实际运行模式,研究3种不同优化场景下各机组热电负荷及煤耗变化,得出不同负荷下的厂级热电负荷运行优化策略。结果表明：全厂热电负荷统筹调控的节煤效果明显优于机组独立运行时的优化结果,最大节煤量可达18.23t/h。此时,为获得更好的节煤效果,应优先考虑热电比高的机组(4号机组)承担最大的热、电负荷,其余由其它机组补充。具体而言,电负荷和热负荷分配优先级均为：4号机组>2号机组>1号机组>3号机组。该研究结果对提高热电联产机组供热运行优化和电厂精细化管理水平具有十分重要的参考价值。     

超临界600MW汽轮机运行方式的优化研究

阐述了汽轮机变负荷运行的优化原理,介绍了某电厂600MW超临界汽轮机组变负荷运行优化试验的情况,并按照机组高调阀的实际流量特性,通过不同典型负荷下（包括540MW、480MW、420MW、360MW、330MW和300MW共6个负荷）的热效率对比试验,得到了机组优化后的变负荷运行方式,考虑了机组排汽压力的修正,给出了相应运行曲线的拟合函数.结果表明：优化后的运行方式在机组低负荷运行时,汽轮机热耗率明显降低,优化后的运行方式有效地提高了机组变负荷运行时的经济性.     

火电机组间负荷优化分配算法比较与分析

负荷优化分配是电厂节能和运行优化的重要研究内容。在全厂机组组合方式一定的情况下,各台机组间合理的优化分配负荷可以提高整个电厂运行的经济性。为此,文中应用二次规划原理对某电厂4台300MW机组并列运行时的负荷分配进行优化。结果证明,它比线性规划分配负荷的调度方式所用煤耗明显降低。     

基于分支限界法的火电机组负荷分配研究

针对大规模新能源并网调峰问题,提出不同调峰阶段火电机组负荷分配方法：分析火电机组调峰能力、调峰成本及二者之间的关系;以总煤耗成本、机组启停成本之和最小为目标,建立不同调峰阶段火电机组负荷分配优化模型;根据火电机组爬坡率、滑坡率,提出参与负荷分配机组的组合策略,并使用分支限界法对负荷分配优化模型求解。算例表明,随着火电机组调峰深度的增加,机组煤耗成本和启停成本减少,深度调峰运行下附加煤耗成本和机组损耗成本增加。     

基于模型预测的多模式供热电厂机组间负荷优化分配调度研究

为解决热电厂机组间负荷分配不合理的问题,提出一种基于模型预测的多模式供热电厂多机组间负荷实时优化分配方法。基于模块化建模原理构建热电厂全厂范围的机理仿真模型,并运用运行数据对模型辨识校准,根据机组特性和电网调峰补贴政策,建立全厂的运行经济性收益评估模型,进而设计基于粒子群算法的负荷实时优化方法,借助性能预测模型预测评估各方案的经济性。以某包含高背压、切缸、抽汽、光轴4种供热模式机组的电厂为例,对不同电、热负荷组合工况下的厂内负荷进行优化分配研究。应用结果表明：该方法可根据热、电负荷的实时指令在线获得经济性优化的厂内机组间负荷分配方案。     

热泵系统中的多机组运行负荷配比优化研究

基于某建筑的全年逐时能耗模拟数据,通过MATLAB软件的非线性结构优化功能对热泵系统中多台机组的运行负荷配比方案进行优化,提出最优的机组运行负荷配比方案。研究表明:在逐时负荷大于单台或多台机组装机容量时,随着逐时负荷增加到运行机组总装机容量的70%左右时,各台机组运行负荷占各机组额定容量的百分比趋于相同;热泵系统采用最少台数的机组运行可有效提高系统的运行性能。根据部分负荷下机组负荷配比原则,给出机组在不同日负荷特性曲线下的运行方案。     

大型火电机组优化运行技术的研究

提出了大型火电机组负荷优化分配技术和运行优化技术。介绍了大型火电机组的负荷优化分配的数学模型、求解技术以及大型火电机组运行优化的关键技术，给出了黄台发电厂的应用实例。     

火电厂多机组负荷经济分配方法

针对SIS系统火电厂多机组负荷经济分配的要求，从单元机组锅炉和汽轮机设计计算书或性能考核试验数据出发，结合单元机组实时性能计算和耗差分析的原理，提出了一种可以同时解决机组负荷特性线的获取和机组负荷特性线的实时修正问题的火电厂多机组负荷经济分配的方法。该方法计算简捷、实时性强，在获得负荷优化分配结果的同时，给出了负荷优化分配的准确效果。     

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.     

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.     

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.