油混水控制器校验装置研究与设计

油进水是水电厂的透平油系统频繁发生的一类事故，通过对两起典型的油混水事故分析得出，密封破裂、冷却器铜管破损等原因引发的油系统进水事故会对水电站的安全生产造成不同程度的损害，而准确可靠的油混水监测装置可以很好地控制该事故的危害扩大。据此分析了油混水控制器校验装置的设计要求、难点，设计实施了一种操作便捷的油混水监测校验装置。     

水轮发电机推力轴承油冷却器泄漏原因分析

葛洲坝水电厂水轮发电机推力轴承油冷却器存在着漏油现象，对机组的安全生产造成极大的威胁。经分析其原因是；运行条件恶劣，泥沙磨损，冷却铜管在安装时有划伤或刺破处，冷却管弯曲处有应力集中，管路老化以及停机时冷却管内有负压现象等。针对上述原因，在检修中更换了老化的管路，装配时采取保护措施防止铜管被划伤，安装时严禁碰撞油冷却器，进行打压试验及早发现泄漏处并及时处理，同时在停机时断水前先关闭冷却器所有进出水阀门，通水时先打开水阀通水再打开排水阀以防止管路产生负压。这样就可以确保推力轴承油冷却器运行安全。并建议安装油混水动态监测装置，以监测冷却器的运行状况。     

一起上导油槽油混水原因的分析与处理

针对上通坝电站1号机组发生的一起上导油槽油混水事故,通过查找事故前后数据,对相关设备进行检查,发现是油流冲击致使油冷却器铜管与固定钢板间碰撞破损导致漏水,进而引发油混水,油冷却器结构设计问题是导致油混水的根本原因,经采取相应的处理措施,保证了电站的正常运行。     

大型水轮发电机组下导轴承油混水分析及处理

构皮滩发电厂1号发电机组已投运12年有余,下导轴承内置冷却器内壁锈蚀严重导致壁厚变薄,出现不同程度无法修复的砂眼,造成油混水情况。油混水将会对机组的安全稳定运行构成严重威胁,会直接破坏轴瓦油膜,降低冷却效果,引起瓦温升高,从而导致烧瓦事故,使机组发生非停,造成巨大的经济损失。因此,为防止事故发生,需对下导轴承冷却器进行更换,保障机组安全稳定运行。     

一次轴承油位异常情况的分析和处理

株树桥水电站2号机组上导轴承油位出现忽高忽低现象,文章分析润滑油散热冷却的工作原理、水冷却器的结构和上导油位异常现象,将上导油冷却器铜管砂眼处用铜焊补焊修复,用0.4 MPa水压试压30 min铜管无渗漏,装复上导油槽盖,调整上导瓦间隙,加油后油位异常现象恢复正常,确保了机组安全。     

大型水电站推力/下导油槽甩油分析及处理工艺

该水电站水轮发电机组推力/下导轴承由于厂家设计原因,在现场安装过程中无法达到设计时的精度,后期运行中均出现不同程度的甩油。机组投运以后,电厂经过不断分析,弄清了机组推力/下导甩油的2种主要情况,利用机组检修的时机,对机组推力/下导油槽结构进行了多次改造,最终使得机组甩油情况得到了大幅改善,基本上消除了推力/下导油槽甩油。     

水轮发电机组推力冷却器锈蚀穿孔分析及治理

推力轴承冷却器在运行过程中大量漏水,将会导致推力轴承油槽油温、瓦温升高甚至是烧瓦,并导致机组出现非计划性停运的风险。通过对构皮滩发电厂推力冷却器底座材质、运行水质及运行环境等多方面分析,找到其锈蚀穿孔的原因,提出相关处理建议,为水电站相关专业运行维护人员提供处理相似问题的理论依据与实际经验。     

推力轴承油冷却器的使用及改造

蚌埠闸水电站发电机的推力轴承油槽冷却器,材质用黄铜(φ20×2),总长约60m左右。过渡接头采用钢板方盒与铜管焊接而成。正常使用水压力为0.05～0.1MPa,冷却效果良好,推力瓦温升在30～42℃之间。 1 冷却器的使用情况 运行中,发生两次冷却器出水侧泄漏,致使上导瓦缺油,4块巴氏合金瓦均被烧毁。停机检查,未发现溢油管溢油及甩油现象,却发现油被吸入漏处,随水流排到尾水管。 原因分析:机组运行时,压力水从下层进口流入,经冷却器到上层出口管,最后在     

桥巩水电站灯泡贯流式机组组合轴承润滑油系统及上下游密封油档技术改造

桥巩水电站灯泡贯流式机组投入运行后,机组组合轴承正推力瓦瓦温较高、组合轴承上下游密封油档存在渗油现象.根据设备结构特点,文章介绍对组合轴承瓦温较高和上下游密封油档渗油现象进行原因分析及处理,解决了组合轴承瓦温较高和上下游密封油档渗油问题,为其他工程类似机组安装提供一定的借鉴经验.     

大岗山电站发电机油雾问题研究与治理

发电机推力轴承油雾外逸是大型机组存在的较为普遍的问题。为彻底解决大岗山水电站发电机推力轴承油雾大的问题,水电站运行管理单位对推力轴承油雾产生的原因进行了分析和研究,提出了解决方案和处理措施,并结合机组检修对推力油槽吸油雾装置进行升级改造,改造后经过一段时间的观察运行,发电机推力轴承油雾大的问题得到有效缓解,取得了不错的治理效果,可为其他同类型发电机组借鉴和参考。     

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。     

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.     

浙江省水域调查录入系统的设计和应用

浙江省水域调查录入系统将调查数据与电子地图相整合,对分类水域数据进行统计计算,并对输入数据进行合理性和完整性检查,得到调查范围内现有水域的详细数据,实现了水域调查数据输入、计算、统计和查询的数字化管理,提高了工作效率和工作质量,为各地下阶段水域保护规划编制和水域管理工作提供了数据支持。对该系统的设计原则、功能和技术设计等作了介绍。     

Automated system for removal and pneumatic transport of fly ash from electric precipitator hoppers

A system for removal and pneumatic transport of fly ash is examined, in which air pulses act on batches (pistons) of ash formed in a duct. Studies are made of the effect of several physical parameters on the force required to displace a piston of ash and these serve as a basis for choosing a system for removal and pneumatic transport of ash simultaneously from several hoppers of an electric precipitator. This makes it possible to separate the ash particles according to size without introducing additional components. Formulas are given for calculating the structural and dynamic parameters of this system and measurements of indirect dynamic parameters are used to calculate the input-output characteristics of the system. In order to optimize the system, configurations for summing several ducts into a single transport duct for pneumatic ash transport are proposed. Some variants of dry ash utilization and the advantages of producing of size-separated particles are considered. __________ Translated from élektricheskie Stantsii, No. 2, pp. 26–30 (2008).     

The flood pulse advantage and the restoration of river-floodplain systems

The ‘flood pulse advantage’ is the amount by which fish yield per unit mean water area is increased by a natural, predictable flood pulse. Evidence for this increase is presented from tropical and temperate fisheries. It is argued that increasing multispecies fish yield by restoring the natural hydrological regime is consistent with increasing production of other trophic levels and with restoration from ecological and aesthetic viewpoints. When applied to a river-floodplain system, this restoration would provide a large, self-sustaining potential for recreation, commercial exploitation, and flood control. An interim ‘natural flood pulse’ restoration approach is proposed for systems modified for navigation. This approach approximates the natural hydrological regime in a river reach and is intended as a first step in the long process of restoring the watershed.     

基于CT-连续加荷水泥乳化沥青混凝土细观损伤规律研究

利用CT技术对水泥乳化沥青混凝土的细观损伤过程进行实时扫描观测,获得了混凝土试件在连续加荷下的CT图像。通过采用直观分析法、CT数分析法、CT数与损伤变量关系3种方法分析表明,水泥乳化沥青混凝土的破坏过程可分为压密、扩容、裂纹扩展、破坏4个阶段,同时混凝土在受压过程中具有韧性,在极限荷载之前各断面处于压密和微扩容的强化阶段,极限荷载之后混凝土从损伤到破坏发展比较平稳。     

Desiccation and recolonization of phytobenthos in a regulated desert river: Colorado River at Lees Ferry,Arizona, USA

We tested the recolonization of the phytobenthic community in the tailwaters of Glen Canyon Dam following long- and short-term experimentally induced desiccation. The response of Cladophora glomerata, Oscillatoria spp., miscellaneous phytobenthos species and periphyton was studied over 18 weeks using three treatments: (1) undisturbed control cobbles from the submerged zone; (2) cobbles desiccated and replaced into the submerged zone; and (3) cobbles desiccated and replaced into the varial zone. Periphyton density and compositional response resulting from these treatments were also examined. Desiccation treatments were significantly different in biomass from controls throughout the study. The biomass of desiccated and replaced river cobbles averaged <30% of the controls for C. glomerata and periphyton during the 18-week recolonization period. In contrast, the biomass of the control Oscillatoria and miscellaneous phytobenthos species averaged only 3 and 50% of that in the desiccation treatments, respectively. Cladophora, the dominant alga, comprised 77% of the phytobenthic biomass. A significant positive relationship between discharge, Cladophora and periphyton biomass was present in all treatments, while there was a negative relationship with discharge for Oscillatoria and miscellaneous phytobenthos species. There was a significant inverse correlation, as well as a pattern of separate biomass dominance, between C. glomerata and Oscillatoria. Cladophora was the dominant phytobenthos species on cobbles below the baseflow and Oscillatoria was dominant on cobbles in the varial zone. In general, the Cladophora biomass decreased under intermittent drying conditions, while Oscillatoria declined under permanently wet conditions. Diatom composition was not significantly different between treatments; however, their density was lower on desiccated cobbles. Diatom density on desiccated cobbles in the submerged and varial zones averaged 69 and 42% of that of the controls, respectively. Recovery and maintenance of benthic resources are hindered by fluctuating flow regimes driven by electricity and irrigation requirements. Repeated desiccation of the phytobenthos has major effects on the bottom-up interactions in the Colorado River ecosystem. © 1998 John Wiley & Sons, Ltd.