温度和气氛对PAHs由从头合成反应生成PCDD／Fs的作用

城市生活垃圾焚烧炉产生的多氯二苯并二恶英(PCDDs)和多氯二苯并呋喃(PCDFs),是一类剧毒的持久性有机污染物(POPs).多环芳烃是城市生活垃圾焚烧炉上二恶英生成的一种主要的碳源.在小型试验用固定床反应器上,研究了温度和燃烧气氛中氧对多环芳烃在模拟飞灰(MFA)的催化下,由从头合成反应生成二恶英的作用.烟气样品参照USEPA1613方法收集,并采用高分辨色谱,低分辨质谱仪进行分析.给出了反应中生成的二恶英的分布特征与温度、氧含量的关系,二恶英的分布特征包括二恶英的总排放量、毒性当量(TEQ)和PCDDs/PCDFs的比例.结果显示,PAHs反应生成的PCDFs的量要比PCDDs高出几倍,在二恶英的生成过程中存在一个最优化的温度区间和氧含量范围,二恶英的毒性当量随着氧含量的增加而增大,并讨论了温度和燃烧气氛的作用机制.     

组织样品中二恶英和多氯二苯呋喃快速萃取法研究

分别采用快速萃取法和石统的索氏萃取法萃取组织样品中的二恶英（PCDDs）和多氯二苯呋喃（PCDW）,采用高分辨率的气相色谱法,质谱法同位素稀释法进行分析;对两种萃取方法的数据进行比较,结果表明。快速溶剂萃取法具有和索氏萃取法相同的萃取能力,回收率相当,但是节省了大量的时间和试剂。因此,在实验室条件下,快速溶剂萃取法是一种可以替代索氏萃取法的新方法。     

5．利用气相水还原法进行PCB污染物处理

气相水还原法是加拿大生态公司以难分解有机化合物，特别是PCB(多氯联(二)苯)的无害化处理为目的，在国外已商业化运行的技术。该公司研究小组，对日本的PCB处理技术进行了提携研究。为了取得该技术在日本国内的认证，在日本进行了实证试验，已受到环境厅、通产省的技术评价，目标是今年春登载处理基准。     

一种评判煤灰结渣特性的新方法

针对煤灰结渣特性单一评判指标的预测精度普遍偏低的问题,基于偏最小二乘算法（PLS）和交叉验证理论建立了煤灰结渣特性预测模型,该模型有4个输入变量,即煤灰的软化温度、碱酸比、硅比和硅铝比,1个输出变量,即结渣程度．提出了指标的同向性和异向性的概念,依据所提出的概念对各单一指标对煤灰结渣特性的作用进行了定性分析与讨论,结合拟合方程,给出了煤灰结渣特性的评判依据．通过对测试样本进行检验,结果表明：所提出的PLS预测模型的预测精度远高于单一评判指标的预测精度,所建模型是合理可行的．     

基于深度学习的配电线路瓷绝缘子缺陷识别

考虑当前方法在识别瓷绝缘子缺陷时，受到缺陷类别的影响，导致识别精度较低的问题，提出了基于深度学习的配电线路瓷绝缘子缺陷识别方法。根据瓷绝缘子可靠性测试原理，采用兆欧表测试配电线路电源电压，通过计算配电线路的电源负载特性，引入测试电压波纹系数，对配电线路瓷绝缘子缺陷进行电子信号检测。根据配电线路瓷绝缘子表面的缺陷区域分布规律，计算瓷绝缘子缺陷图像的深度学习中心和隶属度函数。利用深度学习特征的最佳数量，定位检索配电线路瓷绝缘子缺陷特征，通过对瓷绝缘子缺陷图像的二值化处理，实现配电线路瓷绝缘子缺陷识别。实验结果表明，所提方法在识别瓷绝缘子脱落、灼蚀时缺陷识别指标都达到了9,破损时缺陷识别指标均控制在8以上，具有较高的识别精度。     

智能变电站虚拟回路自动化校核技术的研究

随着智能变电站的大规模建设,变电站配置描述文件中虚回路配置的正确性及其与现场设备运行的一致性,对智能变电站的安全运行至关重要。为此认真研究了SCD文件的配置信息,在总结大量工程经验的基础上归纳提出了对虚拟回路亦静亦动的自动校核方法：静态校核依次分别进行SCD文件的schema、虚回路语义校验和配置校验,而动态校核则利用故障模拟系统,实现虚回路的闭环测试。所提出的校核方法采用动静结合,可有效保障虚回路的正确性和一致性,快速提高智能变电站的调试效率和运维便利性     

基于智能变电站组合设备仿真测试与集成联调技术方案研究

通过关注新一代智能站二次系统技术,构建全站集成联调仿真环境。该环境包括仿真测试激励源、配套的检测工具、以及相应的后台系统。总结二次设备集成测试技术和二次设备集成测试流程,对仿真测试配套技术、配置数据参数的智能化处理、仿真测试系统开发等新智能站就地层集成测试技术进行分析, 将结果应用于变电站现场以实现快速、高效检测,提高联调效率和现场分析解决问题的能力。结合智能变电站工程中的故障仿真形式,通过母线保护装置性能和电子式互感器校验证明该测试方案科学有效。     

泵热冲击特性测试平台研制及数值分析

从优化试验系统设计角度对冷、热冲击测试平台进行工程设计,对泵闭式试验系统高、低温瞬态特性进行测试分析,应用计算流体力学(CFD)软件Fluent对运行过程中的热冲击测试平台中泵入口前三通管内流场进行了热冲击过程模拟计算,从工程设计角度提高了测试平台测量截面流速和压力的准确性,减少了由装置所引起的不利流态,通过合理设计测...     

基于决策树和支持向量机的智能变电站二次系统防误方法

随着智能变电站的普及,电力系统的安全运行对变电站的二次检修提出了更高的要求。针对二次设备状态转换过程中易发生误操作的现问题,提出了一种新型二次系统防误方法。通过测量装置获取一二次设备状态值,构建初始样本数据集。为获取模型所需的特征向量集,采用了PCA法实现数据降维,特征向量集通过决策树实现二次操作分类。对分类后的样本集进行SVM训练和测试,实现二次设备操作的防误判别。最后构建了防误模型,用历史运行数据进行仿真测试,验证了此方法防误判别的有效性。     

16PC2-6中速柴油机NOx排放测试及分析

介绍了对引进的16PC2-6柴油机所进行的NOx排放测试,分析了该排放测试结果,并提出了控制其NOx排放的改进方案。     

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.