单导叶接力器导叶不同步原因分析及故障处理

广州抽水蓄能电厂二期的水泵水轮机为高水头、大容量、高转速的混流式可逆机型。采用单导叶结构可以简化导水机构布置,提高单个导叶的可控制性。经多年检修经验得知,导叶不同步故障是导水机构故障的主要原因之一,从多个方面分析了导叶不同步故障的原因及解决方法,对导叶不同步故障的原因分析及处理有一定指导意义。     

抽水蓄能机组单导叶控制调速器常见故障模式及维护策略

结合多年抽水蓄能机组运维经验,对单导叶控制调速器各种故障模式的识别方法、预防措施、故障处理等进行深入分析,制定对应的维护策略,以减少故障发生的概率,充分发挥单导叶控制调速器的优点。广蓄B厂针对近年来单导叶控制调速器发生过的故障制定的维护策略具有针对性,取得较好效果。     

灯泡贯流式机组导叶外环磨损原因分析及处理

导水机构作为水轮机重要组成部件,导水机构的运行状态影响着整个机组的稳定及安全。控制环在整个导水机构中起着传递导叶开度的作用,其中控制环与导叶外环直接接触,导叶外环承载着控制环的转动力矩及摩擦力矩,导叶外环在水电站日常运作当中发挥着不可替代的作用。它的状态正常与否将决定着机组的稳定性及安全性。因此做好水电站导叶外环的检修及日常维护工作十分重要。本文主要以导叶外环的磨损故障为例,分析可能产生磨损的原因,提出有效的解决办法及预防措施,以保证机组的安全稳定运行。     

广州蓄能水电厂B厂机组导叶轴套选型研究

广州蓄能水电厂B厂4台机组自投产以来,多次出现导叶轴套漏水、损坏等问题,尤其8号机组频繁出现G工况启动时导叶拒动故障。通过综合比较分析,决定后续机组大修选用500SP1-SL464铜基镶嵌自润滑轴套替换500SP1-SL401轴套。8号机组于2012年2月完成大修,从实际运行情况来看,目前导叶轴套未发现漏水,导叶静态试验中导叶开关顺畅,机组小修时检查上下抗磨板无摩擦痕迹,导叶端面间隙正常无变化。     

水轮机导水机构的结构改进设计

现有的水轮机主要采用连杆式导水机构。为简化结构同时减少原材料的消耗,降低生产和制造成本,取消其连杆组件,将连杆式导水机构改为滑块式导水机构,由控制环直接带动导叶臂转动,调节导叶开度,以控制水轮机的流量。该结构简单、新颖,安装、维护方便,实用性强,提高了生产企业和电站的经济社会效益。图6幅。     

水轮机导叶摩擦装置的设计研究

在水轮机组运行中,导水机构通常是利用导叶臂与连板间的剪断销起过载保护作用,在控制环带动活动导叶向关闭方向运动,某些导叶发生卡阻,外力大于正常的关闭力一定值时,相应剪断销就会被剪断。目前有些机组则采用新型的导叶摩擦装置。文章介绍了导叶摩擦装置的主要结构和工作原理,提出了导叶摩擦装置设计时的主要参数,如压紧螺栓的直径大小、压紧螺栓预紧力矩大小的计算方法。     

长洲水利枢纽水轮发电机组重锤关机装置简介

重锤关机作为灯泡贯流机组最有效的防飞逸措施得到了广泛的应用,且重锤关机装置具有多种型式,各有特点。该文针对长洲三个主机厂生产的灯泡贯流式水轮发电机组,介绍其重锤关机装置的原理及主要特点。其中,A厂机组采用单作用导叶接力器模式,B厂采用双作用接力器结合事故配压阀模式,C厂机组采用双作用导叶接力器模式。当机组因事故甩负荷遇调速系统故障而不能正常关机时,三种装置均能实现安全关机,能有效地防止机组飞逸。     

龚嘴水电站机组导叶传动机构的结构改进与技术改造

对龚嘴水电站不同历史时期机组导叶传动机构的结构特点、运行情况进行了分析、比较,为上世纪60、70年代投产机组导叶传动机构的结构改进和技术改造提供了借鉴和参考.     

几种灯泡贯流式机组导水机构工装简介

导水机构是灯泡贯流式水轮发电机组的重要组成部分,主要由外配水环、内配水环、导叶、传动机构、调速机构等部件构成,其主要功能是使水在进入转轮前产生水流环量,并根据机组功率的需要开关导叶调节水流流量,达到预定的出力,水轮机停止运行时,导叶分段关闭切断水流。根据导水机构的结构特点,单支导叶具有各自的传动、调速机构,安装工序较为复杂,单个导叶系统安装调整完毕后方可进行整体的组装,为了提高安装质量及安装效率,介绍几种实用的导水机构工装。     

抽水蓄能电站导水机构的安装施工技术探析

导水机构是水泵水轮机的关键部件,运行环境较为复杂,主要是由导叶、导叶传动机构、导水机构接力器和项盖、底环、控制环等一系列部件组成。根据抽水蓄能电站导水机构的安装程序与技术要点,以海南琼中抽水蓄能电站导水机构安装施工为例,确定导水机构安装工作内容与流程、导水机构安装施工。导水机构安装施工主要包括底环、导叶、顶盖、控制环、拐臂和接力器的组装和安装。最后,提出施工质量保证措施,可为抽水蓄能电站导水机构的安装施工提供保障。     

Call for Papers

正As the eldest and most distributed professional journal of water industry,Water Wastewater Engineering(W WE)gained very wide acceptance from the colleagues working in this field in this country since start publication in 1964.Now it is administrated by the Ministry of Construction of the People’s Republic of China and sponsored by the China Civil Engineering Society etc.     

地下厂房施工过程的三维非线性数值模拟分析

根据冗各电站地下厂房开挖支护的施工顺序,以隐式杆单元模拟锚杆,以壳单元模拟混凝土喷层,采用三维非线性有限元技术,对洞室群的开挖支护动态过程进行了模拟计算。通过三维非线性有限元计算分析得到:洞室群动态开挖过程中围岩应力变形的分布规律,围岩塑性区的发展规律,锚杆受力变化情况。计算结果表明:整个开挖过程中,洞周围岩位移变化规律正常,量值较小,塑性区主要分布在洞室周边,围岩稳定性较好;但在洞室交叉口处围岩的变形较大,出现较大范围的塑性区,在此基础上提出了支护措施优化方案,并对优化方案的效果进行了评价。     

Evaluation of freshwater mussel relocation as a conservation and management strategy

The relocation of unionacean mussels is commonly used as a conservation and management tool in large rivers and streams. Relocation has been used to recolonize areas where mussel populations have been eliminated by prior pollution events, to remove mussels from construction zones and to re-establish populations of endangered species. More recently, relocation has been used to protect native freshwater mussels from colonization by the exotic zebra mussel Dreissena polymorpha. We conducted a literature review of mussel relocations and evaluated their relative success as a conservation and management strategy. We found that 43% of all relocations were conducted because of construction projects that were forced to comply with the Endangered Species Act 1973 and that only 16% were monitored for five or more consecutive years. Most (43%) relocation projects were conducted from July to September, presumably a period when reproductive stress is relatively low for most species and the metabolic rate is sufficient for reburrowing in the substrate. The mortality of relocated mussels was unreported in 27% of projects; reported mortality varied widely among projects and species and was difficult to assess. The mean mortality of relocated mussels was 49% based on an average recovery rate of 43%. There is little guidance on the methods for relocation or for monitoring the subsequent long-term status of relocated mussels. Based on this evaluation, research is needed to develop criteria for selecting a suitable relocation site and to establish appropriate methods and guidelines for conducting relocation projects.     

基于模型试验的河床砂砾石层基本特性研究

为了经济可靠地确定深厚覆盖层的基本特性参数,以大渡河双江口水电站坝基河床砂砾石层基本特性研究为工程背景,进行大尺寸模型试验,研究河床砂砾石层的旁压模量和动探击数随密度、级配以及上覆压力的变化规律。根据室内模型试验结果,结合现场旁压试验及钻孔试验成果,推断出坝址区河床砂砾石相关层位的密度,并依此进行砂砾石室内力学试验,获得设计所需力学参数。研究成果可为深厚覆盖层基本特性测试提供新的方法。     

库水波动下库岸边坡地下水浸润线解析解及误差分析

解析法是库岸边坡地下水浸润线计算中便于实际应用的方法,但该方法须基于若干假定并对潜水运动基本方程线性化后才能求解。针对各假定和线性化过程建立不同的地下水渗流数学模型,用解析法和有限元法解答上述数学模型,分析各误差大小及其规律。结果表明：库岸垂直处理带来的误差要小于方程线性化处理和不考虑非饱和渗流带来的误差,而且它们都随渗透系数变大而减小;在三峡库区库水调度情况下,假定库水位等速变化带来的误差对大多岸坡而言可以忽略;计算库岸边坡地下水浸润线时,解析法只适用于水位变化幅度相比含水层厚度较小,且几何边界规则、岩土结构简单、岩土体渗透性较好时的情况。     

SPATIAL AND TEMPORAL WATER QUALITY VARIABILITY IN AQUATIC HABITATS OF A CULTIVATED FLOODPLAIN

The floodplains of lowland rivers contain diverse aquatic habitats that provide valuable ecosystem services but are perturbed when intensively cultivated. Hydrologic, water chemistry and biological (fish) conditions in five aquatic habitats along the Coldwater River, Mississippi, were measured for more than 4 years: the river, two severed meanders that functioned as backwaters, a managed wetland and an ephemeral channel draining cultivated fields. Off‐channel habitats were connected to downstream regions 0.10% to 32% of the dry season and 24% to 67% of the wet season. The median temperatures for the five monitored sites ranged from 18°C to 23°C, the median total solids concentration for all sites was 135 mg L^?1, the median total phosphorus was 0.29 mg L^?1 and the median total nitrogen was 1.56 mg L^?1. Chemical and physical water quality displayed strong seasonal differences between the wet winter/spring and the dry summer/fall periods so that temporal variation consisted of gradual seasonal trends superimposed on strong diurnal variations. All off‐channel habitats exhibited periods of hypoxia and temperatures >30°C during the dry season. Between‐site gradients of water and habitat quality were strongly coupled to water depth and runoff loading. The rehabilitation of one backwater by increasing water depth and diverting agricultural runoff was associated with improved water quality and fish species richness relative to an adjacent untreated backwater. The diversion of polluted runoff and the use of water control structures to maintain greater water depth were observed to be effective management tools, but the former reduces the water supply to habitats that tend to dry up and the latter reduces connectivity. Published in 2011 by John Wiley & Sons, Ltd.     

Changes in Summer Irrigated Crop Area and Water Use in Southeastern Turkey from 1993 to 2002: Implications for Current and Future Water Resources

Changes in summer irrigated cropland acreage and related water use are estimated from satellite remote sensing and ancillary data in semi-arid Southeastern Turkey where traditionally dry agricultural lands are being rapidly transformed into irrigated fields with the help of water from the Euphrates-Tigris Rivers. An image classification methodology based on thresholding of Landsat NDVI images from the peak summer period reveals that the total area of summer irrigated crops has increased three-fold (from 35,000 ha to over 100,000) in the Harran Plain between 1993 and 2002. Coupled analysis of annual irrigated crop area from remote sensing and potential evapotranspiration based estimates of irrigation water requirements for cotton indicate a corresponding increase in agricultural water use from about 370 million cubic meters to over one billion cubic meters, a volume in accordance with the state estimates. These estimates have important implications for understanding the rapid changes in current agricultural withdrawals in Southeastern Turkey and form a quantitative basis for exploring the changes in future water demands in the region. For example, expansion of irrigated lands have led to a steady decrease in potential evaporation due to increased roughness and decreased humidity deficit in the Harran Plain. Assuming that the changes in future evaporation conditions will be of similar nature, water use for irrigation is expected to decrease over 40 percent in future irrigation sites. Incorporating this decrease in overall planning of the irrigation projects currently under construction should lead to improved management, and by extension, sustainability of water resources in the region.     

基于BP神经网络-马尔科夫链模型的隧道围岩位移预测

在隧道工程施工中,围岩位移预测起着很重要的作用。将BP神经网络-马尔科夫链模型引入到隧道围岩位移预测中来,通过对训练样本的学习,利用BP神经网络实现了对位移时间序列的滚动预测,同时得到了实测值与预测值的相对误差;在此基础上利用马尔科夫链对相对误差进行修正,有效地提高了预测结果的精度。并将该模型应用于某公路隧道拱顶下沉位移时序预测中,结果表明该模型具有精度高、科学可靠的特点,为隧道围岩变形的预测提供了新的途径。     

Short communication. Pipelines as a refuge for freshwater snails

In the lower River Murray, Australia, populations of gastropods have declined markedly over the past 40 years. Of the native fauna of about 18 species, only the ancylid Ferrissia petterdi remains common (but in patches), and another five species feature in sporadic local resurgences. Until recently the viviparid Notopala was thought to be extinct. The introduced physid Physa acuta is widespread, but in low numbers. The decline probably is associated with flow regulation, high turbidity and the introduction of common carp. Snail populations have persisted, however, in irrigation pipelines fed from the river, where they periodically cause blockages. This paper reports the discovery of the only known populaion of Notopala hanleyi in a pipeline where the inner wall accumulates microbial and other organic matter, providing high quality food for snails. In the Murray before regulation most of the periphytic biomass was probably microbial, as fluctuating water levels would have maintained littoral communities in a highly productive, early state of succession his postulated that, by stabilizing seasonal water levels, regulation has promoted the production of filamentous green algae, an inferior food source, and so displaced snail populations from the open aquatic environment.     

Spatio‐temporal variation of gross CO2 and CH4 diffusive emissions from Australian reservoirs and natural aquatic ecosystems,and estimation of net reservoir emissions

Carbon dioxide (CO₂) and methane (CH₄) diffusive emissions were measured during two field surveys in Queensland and Tasmania, Australia, using the floating chamber method. Bubbling and degassing emissions in 2010 were estimated in Koombooloomba Dam reservoir using only inverted funnels and gas concentrations, respectively. A total of 14 reservoirs and 16 rivers and lakes were sampled from 2006 to 2010. Spatial variation was substantial within each water body, as well as between them. The main drivers of diffusive emission variation were physiographic region and climate, with a clear demarcation being observed between diffusive emissions from tropical Queensland and temperate Tasmania, and between the humid West Coast Range (Tasmania) and dry Central Plateau (Tasmania). Higher CO₂ and CH₄ diffusive emissions were observed during the dry season, when long water residence times would promote organic matter degradation. Estimated total gross emissions, including diffusive, bubbling and degassing emissions, for Koombooloomba Dam reservoir were about 1.5 × 10⁶ t CO₂eq km² per year, or 24 × 10⁶ t CO₂eq per year. This corresponds to a plant emission factor of 3.18 kg CO₂eq MWh^?1. Using an estimate of terrestrial emissions derived from literature data for the Tully River catchment area, rough estimated net emissions from the catchment area are about 44 kt CO₂eq per year, or 5.83 kg CO₂eq MWh^?1, which is in the lower range of the studied reservoirs.