尾水支管长短对相继甩负荷尾水管进口最小压力的影响

抽水蓄能电站相继甩负荷过程中两台机组的流量相互影响,尾水支管长短对尾水管进口压力的影响很大。通过理论推导结合对实际工程的数值模拟,分析了后甩机组尾水支管长短对相继甩负荷后甩机组尾水管进口最小压力的影响。结果表明,机组流量变化率大小决定尾水支管长短对自身机组尾水管进口最小压力的影响程度,与同时甩负荷相比,相继甩负荷后甩机组的尾水管进口最小压力对自身机组尾水支管长短更敏感;固定上、下游岔点位置,移动机组使其靠近下游岔点,可减小尾水支管水流惯性、增大相继甩负荷尾水管进口最小压力,该措施可代替降低机组安装高程的方法。     

汽包锅炉负荷-压力-水位简化非线性动态模型

针对汽包锅炉负荷-压力-水位之间的耦合关系以及水和水蒸气热力性质的复杂性,提出一种新的火电机组建模思路:建立机组负荷-压力对象的能量平衡方程和水位对象的质量平衡方程,再分别增加质量修正和能量修正,从而得到微分方程形式的锅炉燃料量-汽轮机高调门开度-给水流量与机组负荷-机前压力-汽包水位之间的多变量简化动态模型.对某600 MW机组在不同负荷下进行了扰动试验,结果表明:此模型能够反映对象主要的动态特性和非线性特性.     

燃气-蒸汽联合循环发电 机组设备工 况变化 对机组起 动的影响分析

150 MW燃气-蒸汽联合循环发电机组的主燃料为轻油和高炉煤气。经过一系列对余热锅炉和煤气 压缩机的设备更新改造，机组工艺状 态与原先设计的工艺状 态不一致 ，控制 系统内部参数 与现有工况参数不匹配 ，导机组启动失败。重点分析 燃气轮机负荷出力与蒸汽 轮机负荷出力之间平衡 导致得 机组工况晃 动 对煤气压缩 机防喘振动控制 的影响 ，以及手动控制蒸汽 轮机高压调门开度 和煤气压缩 机防喘振阀门开度来 稳定煤 气流 量从而避免工况晃动触发煤气压缩 机防喘振 保护脱扣 。     

水火电混合系统分时运行模拟与发电计划

给出了发电计划应用的两个实际问题的解决方案。通过对等效负荷曲线的时段分解,提出了准确模拟发电机组计划检修、日开夜停、新机投运以及季节性水电等运行状况的算法;提出的分时算法可快速准确确定系统中每一台机组在负荷曲线上的运行位置,即使系统出现若干机组带负荷位置重叠交错的情况,也可计算各机组分时发电计划。该算法已开发可确定与逐小时负荷水平相应机组出力及开停机安排的自动发电计划程序。通过计算实例,对算法的实用性和有效性作了进一步说明。     

相继甩负荷间隔时间与尾水管进口压力最小值的内在联系研究

为探求相继甩负荷间隔时间与尾水管进口压力最小值之间的内在联系,针对双机一洞布置型式的抽水蓄能电站,基于瞬变流理论和特征线法对相继甩负荷工况水力过渡过程开展数值模拟,分析了相继甩负荷工况下机组流量变化率和运行轨迹与尾水管进口压力最小值之间的联系。结果表明,存在某一最不利相继甩间隔时间使得两台机组第一波流量变化率的时域不同步程度达到最大,则对应的尾水管进口压力达到最小,且此时先甩和后甩机组运行轨迹点分别在特性曲线反S区上弯点和下弯点。研究结果可为抽水蓄能电站尾水管进口压力极值计算提供参考。     

电厂实时主蒸汽压力优化软件开发

为了实现节能降耗的目的,针对300MW大型火力发电机组,开发了主蒸汽压力实时优化系统。提出以热力系统矩阵方程为基础的机组运行状态重构方法。采用机理分析法和统计法相结合的混合建模思想,在保证运行参数规律的基础上提高了模型的计算精度。应用Delphi编程及Mysql数据库,实现了电厂机组主蒸汽压力实时优化,对电厂运行进行指导。软件应用表明:在100%负荷与80%负荷时,采用定压运行;在80%负荷以下采用滑压运行;热耗优化量随着负荷的升高逐渐减小。     

热电联产机组热力特性计算解决方案

运用等效焓降的分析方法将供热机组拆分为纯凝机组与背压机组,并通过平衡轴系做功与回热系统吸热量的方法计算出在不同压力等级供热工况下对汽轮机热耗率的影响。通过minitabo软件的使用计算出电、热负荷分配对中压缸效率的影响,并组织验证试验。     

滑压运行机组给水泵小汽轮机参数应达值的研究

分析了滑压运行机组在部分负荷下运行时,给水泵出口压力和效率,以及小汽机抽汽量等参数的应达值计算方法。以某600MW机组为例,计算了不同负荷下各参数的应达值,并与设计值进行比较,结果表明本文采用的方法是可行的,为火电机组进行节能诊断和能损分析提供了理论依据。     

通用压力锅炉控制系统技术规范——启动分离器和低负荷压力流量控制

机组在启动和低于最小给水流量负荷下运行时,要求全部或一部分工质进入启动分离器。这样在保持水冷壁不过热所需的最小给水流量时,锅炉能够为汽轮机提供合格的蒸汽。图2表示的启动分离器和低负荷压力流量控制系统应该这样进行设计,当机组处于旁路系统运行时,分离器的压力和水位都应自动控制。此外,该系统还应自动控制一次过热器出口压力和汽轮机的进汽量。有关本系统的控制要求分两部分叙述:启动分离器控制和低负荷压力流量控制。     

超超临界1050 MW机组深度调峰控制策略探讨

针对神福鸿电2台超超临界1050 MW机组实际运行情况,提出了通过锅炉低负荷燃烧控制、给水泵汽轮机、引风机汽轮机汽源控制等对应防范措施.经过实际运行对比发现,实施合理的运行参数调整有效的实现了机组深度调峰控制,确保机组安全经济稳定运行.     

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.     

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。     

Contents in Volume 23,2014

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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.