碳纤维复合芯导线的特性及应用

阐述了碳纤维复合芯(ACCC)导线的结构和材料特点,比较了直径相近的ACCC导线与传统钢芯铝绞(ACSR)导线的主要材料性能,绘制了两种导线的应力弧垂曲线,将两类导线在最高气温下的弧垂和应力进行了对比。结果表明,ACCC导线的截面积、最高工作温度、载流量均高于ACSR导线,而弧垂明显小于ACSR导线,在实际工程中ACCC导线弧垂小的优势可明显降低铁塔的高度,进而可减少线路的造价。     

碳纤维复合芯导线过滑车散股现象

针对碳纤维复合芯导线在过滑车后可能出现的散股现象进行了研究。首先对碳纤维复合芯导线过不同底径的滑车进行了有限元分析,得出碳纤维复合芯导线过滑车时随着滑车底径的增大散股现象变小,过20 D滑车时相邻铝线最大散股间距为3.08 mm,过40 D滑车时相邻股线最大距离为0.6 mm。其次通过实验分析了碳纤维复合芯导线过滑车时导线表面的变化以及过不同底径滑车后导线表面的散股程度,选取过滑车后的其中一根试件进行张力为1%RTS、10%RTS、20%RTS、30%RTS条件下导线外观的观察,得出随着张力增大导线散股现象有明显改善。当导线张力在20%RTS以上时导线表面散股现象很小。通过有限元分析以及实验研究得出碳纤维复合芯导线过滑车时散股现象的严重程度与滑车底径成反比,但在实际工程中含张力的情况下散股现象较小。     

圆形耐热硬铝合金碳纤维复合芯导线在500 kV 山区增容改造线路中的推荐分析

浙江电网的林木高度的削减赔偿逐年增加,大大加重了地区输电线路运行维护成本,为减少输电线路下方的林木高度削减次数降低运行成本,同时满足浙江电网的增容需求,浙江电网运行单位要求在增容改造中对已建输电线路更换采用低弧垂导线,以满足增容后不再增加导线弧垂,进而保证导线对树冠的安全距离,结合山区500 kV增容改造工程,对多种低弧垂导线进行特性分析,采用满足工程要求的圆形耐热硬铝合金碳纤维复合芯导线,通过对此种多个型号导线进行载流量、高温弧垂、杆塔荷载、绝缘子金具串强度、悬垂串摇摆角校验及经济比较后,来最终选择此种导线规格参数,经过论证比对后,推荐采用4×JLNR/F1B-375/35圆形耐热硬铝合金碳纤维复合芯导线。     

碳纤维复合芯导线股线应力有限元分析

考虑碳纤维复合芯导线的结构、材料特性,针对JRLX/T-315/40碳纤维导线进行了静力线形分析,并利用SOLIDWORKS软件建立导线实体模型,模拟分析了导线在实际运行过程中受到拉力、剪力和弯矩以及线夹的挤压力时外层股线与线夹接触部位的应力分布情况。结果表明,导线夹持区的应力集中部位主要在U型螺栓出口处和悬垂线夹出口处;在线夹出口处,T_0=0.15Tp时导线与悬垂线夹接触位置的外层中间一根股线的应力损伤最严重;在弯矩和拉力共同的作用下,碳纤维复合芯棒承担导线63%左右的应力,是碳纤维导线的主要承力部件。     

增容导线在上海电网中的应用情况分析

对目前应用较为广泛的几种增容导线进行了介绍,以上海电网中几条实际输送功率较大的220 kV线路为例,探讨了导线增容技术在上海电网中的应用情况。在导线截面相同的情况下,碳纤维芯软铝导线的增容效果与其他类型增容导线相当,甚至更优,但其水平荷载和垂直荷载均明显小于其他类型的增容导线,弧垂特性优势更加明显。其他类型增容导线无论截面大小其弧垂均大于原常规导线,部分碳纤维芯软铝导线的弧垂较原常规导线有所减小。     

绞合型碳纤维复合芯软型铝绞线在线路增容工程中的应用

  [目的]  为解决某220 kV线路增容问题,在工程设计阶段,对常规导线和多种耐热导线进行综合比选。  [方法]  分析了要求输送容量下各型导线的最高运行温度;对比了机械荷载和导线弧垂变化对杆塔基础的影响;计算了不同导线的电能损耗;分析对比了施工运维和建设难度;从一次性投资和年费用上进行经济分析。  [结果]  结果显示:在满足输送容量和导线允许温度的情况下,常规导线方案需全线拆除并新建杆塔和基础;各型耐热导线弧垂和荷载均满足原线路设计条件;常规导线和绞合型碳纤维复合芯软型铝绞线的年费用较低,运维相对便利。  [结论]  绞合型碳纤维复合芯软型铝绞线综合性能较优,适用于利用已有线路杆塔实现线路增容的场合,尤其是在城区或近郊等新建杆塔较为困难的地方。     

ACCC导线的应用和金具的研制

介绍ACCC导线结构、主要品种、技术参数及应用实例,得出ACCC导线具有高强度、高容量、耐高温、耐腐蚀、线损低、低弧垂等技术特性,提出金具国产化研制的设想,供采用ACCC碳纤维复合芯铝绞线的研究、设计、施工参考。     

绞合型碳纤维复合芯导线在新建线路中的应用研究

与目前普及应用的棒型碳纤维复合芯导线相比,绞合型碳纤维复合芯导线具有柔软性能良好、安全稳定性高、连接金具简单和架线施工方便的系列优点,是未来碳纤维复合芯导线的发展趋势。为研究该导线在500 kV新建架空输电线路工程中的应用前景,以两典型500 kV双回交流线路模型为例,分别从节材和节能的角度相应选取碳纤维复合芯导线,与推荐的铝包钢芯铝绞线方案进行综合技术经济比较,总结绞合型碳纤维复合芯导线经济性方面的优劣势,以指导实际工程应用。     

碳纤维复合芯导线在华东电网的应用分析

碳纤维复合芯导线是一种新型增容导线,它在机械、电气性能等方面都有突出的优势。通过对华东电网一条500kV线路的技术经济分析,论述了应用碳纤维复合芯导线增容改造线路,可以节省改造项目成本,但运行损耗比较大。在华东地区,基于不同的具体情况,可以利用碳纤维复合芯导线的性能优势,解决一些特殊环境下的线路增容问题。     

绞型和棒型碳纤维导线主要性能对比及问题分析

研究了两类碳纤维复合芯新型导线(棒型碳纤维复合芯导线、绞型碳纤维复合芯导线)的制造工艺、性能和结构情况等,对比了两种导线的优劣性能。结果表明:两类导线损伤多发生在紧线过程中卡线器临锚处以及压接过程中导线接续金具压接处附近,稳定结构的绞型碳纤维芯和现有配套耐张线夹难以达到默契的配合应用。最后针对上述两个问题提出了解决方案。     

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%.     

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.     

Contents in Volume 23,2014

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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.