水轮机旋转油盆内甩油原因分析与处理

水轮机旋转油盆内甩油会使水导瓦温水升,影响机组正常运行。通过对白鹤水电站1、2号机组水轮机旋转油盆的结构特点和甩油情况的分析,查明了甩油原因,并提出了处理方法。     

水导轴承甩油问题的原因分析及处理方案

<正>机组运行时,水导轴承中的油或油雾跑出轴承油槽的现象,称为轴承甩油。这不仅浪费润滑油、污染环境,有时机组因甩油严重,而致使运行油位下降造成油位过低,引起烧瓦。因此,轴承的甩油一直是轴承设计时的一个需重点考虑的问题。轴承甩油有两种情况:一是润滑油通过主轴轴领内     

小浪底水轮发电机组推力轴承甩油处理

水轮发电机轴承甩油是机组安装、运行中常见问题，目前很难彻底解决这一问题。小浪底水电站安装6台单机容量为300MW的水轮发电机组，其水轮发电机为立轴、空冷、半伞式、三相同步发电机，是具有代表性的水轮发电机。在安装过程中，对小浪底2号机组推力轴承档油管进行了改造，解决了推力轴承甩油问题，对其他机组也起到了借鉴作用。     

水轮发电机轴承甩油原因分析及处理

以某电站水轮发电机轴承部件甩油的治理过程为例,介绍了油雾产生的原理,轴承甩油的原因、处理方案和效果,为水电站治理机组轴承部件的甩油问题提供了借鉴。     

1000 MW核电汽轮机轴承甩油原因分析及优化

某核电厂汽轮机在运行过程中出现轴承甩油至保温棉,并在高温作用下引发火险。通过对润滑油系统和轴承箱内部结构进行阐述,对汽机轴承甩油从装配、润滑油回油、挡油板设计等方面进行了分析,并采取挡油板优化改进方式从根本上解决了甩油问题,提高了机组运行安全性和可靠性。     

水轮发电机推力轴承甩油的处理

针对小山电站2号机组推力漏油问题,通过加大稳油板尺寸、加装挡油圈内挡油板、改变油位等方法进行了综合性的处理,弥补了推力轴承甩油导致碳刷打火这一重大缺陷,保证了机组的安全稳定运行。     

加装止漏环解决水电机组转动油盆甩油的方法

为了有效解决某水电厂投产后出现的水导轴承转动油盆甩油问题,采用在原转动油盆加装止漏环装置方法,对水导转动油盆进行改造.改造后有效地消除了转动油盆甩油的缺陷,确保机组安全稳定地运行.     

乌江渡发电厂＃３机水导轴承甩油处理

分析乌江渡发电厂＃３机水导轴承存在的甩油缺陷,确定该缺陷由机组内甩油引起,并采取消缺处理措施。     

水轮机旋转油盆内甩油原因分析与处理

浙江省白鹤水电站是一座以发电为主的引水式电站，装有2台12.5 MW立轴混流式水轮发电机组。 机组水导轴承结构如图1所示。该机采用反螺旋自循环自冷式轴承，为筒式分半结构。轴承由轴承支架、旋转油盆、轴承体、轴瓦、油箱、冷却器等组成。轴承支架为铸钢，下法兰锁在顶盖上，上法兰承受轴承体，旋转油盆材料为Q235A，锁在主轴上，轴向靠卡槽定位，径向由销定位。旋转油盆分两半面，中分面由22只M12×65的螺栓联接。旋转油盆与旋转油盆盖靠12只M16×40螺栓联接。图1 水导轴承结构图1 旋转油盆内甩油情况 (1) 2000年6月，1号机组投…     

零重力油挡在125MW机组上的应用

以前投产的各类型号机组 ,其轴承箱润滑油的密封油挡均采用固定式有间隙的铜齿油挡 ,这种油挡经过长期运行后 ,间隙越来越大 ,无法起到完全密封的效果 ,由此经常发生沿主轴甩油或漏油现象。金竹山电厂 4台 12 5MW机组和 2台 5 0MW机组也采用这种油挡 ,近年来偶尔发生因油挡沿轴甩油而造成高温区积油冒油烟甚至发生明火现象 ,成为生产的一个潜在的安全隐患。为消除此缺陷 ,大修中在 6号机组 ( 12 5MW机组 )安装了新型的磁力完全密封零重力油挡。从运行情况来看 ,这种新型油挡的密封效果较佳 ,但也存在一些不足之处。1　固定式铜齿油挡与零…     

Feathering and creep [From the Editor's Desk]

It is truly amazing how even the apparently most mundane things can become elevated to the level of science. For this to happen, it must be possible to assess the thing against various attributes or dimensions, but it is not always necessary that those attributes be objectively quantifiable. Instead, all that is required is that there must be parameters that can be used to compare and contrast one version of the thing with another version of the same thing.     

汽轮机高压调节汽阀突然关闭的原因分析及处理方法

介绍了影响汽轮机高压调节汽阀无法开启的主要因素,结合某电厂因节流孔堵塞,造成安全油压无法建立导致的高压调节汽阀无法开启的处理过程,综合分析了各因素导致高压调节汽阀无法开启故障的排除方法,为火电机组汽轮机检修提出了相关指导方法。     

Even‐order passive filters: Pascal versus Chebyshev

The recently reported Pascal approximation with non‐equiripple magnitude response leads to transfer functions of order equal or comparable to that of the Chebyshev approximation, offering an alternative to the equiripple Chebyshev approximation. Both approximations can be used in passive filter design and have similar design limitations when the order turns out to be even. In this paper, these design issues are thoroughly addressed, and the exact conditions are set under which even‐order passive Chebyshev and Pascal filters cannot be directly synthesised and either the order has to be increased to the next odd integer value or the modified filter must be designed. Pascal approximation is used for the first time for the design of doubly resistively terminated passive LC filters, and it is shown that the even‐order design issue is much less restricting making Pascal superior to Chebyshev filters in that even‐order filters can be directly designed to meet specifications that cannot be met by Chebyshev filters of the same even order. The theoretical results are confirmed through several design examples. Copyright © 2012 John Wiley & Sons, Ltd.     

Functional brain imaging using EPI at 3 T

Functional magnetic resonance imaging (fMRI) is becoming an important tool in the mapping of brain activation. However there are two main concerns that need to be answered before functional imaging can be considered truly useful as a neurophysiological tool. The first is that the detected activation may be derived from large veins and, thus, be spatially separate from the underlying brain activity. The second is the incomplete understanding of the brain transfer function and its relation to brain activity, blood flow, and metabolism. This work contains initial results that will help address these points. Models of the brain vasculature predict that signal changes on SE (spin-echo) images are expected to be much smaller in magnitude but very accurate in localizing true areas of activation than on GE (gradient-echo) images which are susceptable to large veins. By comparing activation from SE and GE EPI at 3 T, we have shown that the regions of activation are spatially very similar, suggesting that GE activation is closely linked to the underlying brain activity. We have identified an experimental impulse response of the brain following 8-s visual stimulation. This impulse response can be used to successfully predict the frequency response obtained experimentally and its shape suggests a resonance phenomenon. This suggests the brain transfer function can be modeled from linear response theory corresponding to the inherent feedback control mechanisms of the brain homeostasis. Continuation of this early work will help to identify the links between fMRI signal change and underlying brain physiology.     

Medicine, the borrower [Retrospectroscope]

Medicine has its three goals, curing a disease or arresting its progress, providing relief from pain and suffering, and rehabilitating with the minimum need of a caregiver. Medicine appropriates everything from every source that can be the slightest use to anybody who is ailing in any way or likely to be ailing from any cause. The modern biomedical engineer must be knowledgeable in biology, medicine, and engineering to recognize problems that can be solved by tools or techniques that can be borrowed to solve a medical problem.     

应用进化规划变异算子的配电网重构算法

针对进化规划算法普遍存在的进化过程缓慢和进化后期难以平稳收敛等问题,考虑到配电网重构功率损耗最小和负荷均衡2个目标,提出一种新的进化规划变异算子。为保证变异产生的新个体积极地向最优个体靠拢,一方面使变异算子的拓扑调整次数与进化代数成反比,另一方面在拓扑调整过程中增加待合开关选择算子和待分开关选择算子。同时,为提高整个配电网重构算法的计算速度,研究了功率损耗、二次负荷矩、待合开关选择算子和待分开关选择算子的简化计算方法。所提方法的可行性在河南省商丘供电局的10 kV配电网运行优化与辅助决策系统上得到了验证。     

"标示模式"在县级供电企业生产管理中的应用

有人说“领导是艺术”,有人说“营销是艺术”,但是从来没有人说“生产是艺术”。的确,生产是实实在在,不能放过任何一个细节的工作。如果要说生产也包涵了艺术元素,或许标示管理就是生产管理的行为艺术之体现。     

自然通风湿式冷却塔空气动力场数值分析

对电厂自然通风逆流式双曲线冷却塔内的空气动力场进行了数值分析,并利用PHOENICS计算平台进行了数值模拟。分析结果认为:冷却塔无风运行时,塔内形成负压,压力沿塔高逐渐升高;塔内流场呈轴对称分布时,塔内周向分布均匀,中心流速最大。由于冷却塔的冷却能力受环境的影响很大,还对淋水密度、环境温度、阻力变化等各种变工况进行了计算与比较,发现入塔水温与淋水密度对塔内流场的影响基本相当。     

基于电路理论与正交投影的支路损耗分摊方法

基于正交投影概念,提出一种新的基于电路理论的支路损耗分摊方法。将发电或负荷电流源独立作用下的支路电流分量在支路总电流方向上作正交投影,定义该正交投影分量为电流源对支路的电流投影分量,以此为基础分解支路潮流,实现支路损耗分摊。支路潮流分解结果可作为输电线路利用份额的计算基础。还深入探讨节点注入功率的两种等效方式,指出将所有发电与负荷均等效为电流源的等效方式存在单个电流源独立作用的结果主要取决于对地支路的问题,而将发电与负荷分别依次等效为电流源/等值导纳的等效方式则反映了支路功率分布应主要取决于发电与负荷的分布而非对地支路的实际情况,故应采用该种等效方式。通过算例验证该文方法的有效性。     

A Solution to the Ill-Conditioned GPS Positioning Problem in an Urban Environment

For GPS positioning, it is normally required that there be at least four GPS satellites in view. However, due to the frequent blockage of signals in an urban environment, it is difficult to meet that requirement; therefore, the operation of the GPS receiver may be interrupted. How to deal with this problem so that the service can be continuous is the main theme of this paper. The pseudorange predictor and the receiver clock bias predictor may be used to estimate the pseudorange and clock bias, respectively. The altitude-hold algorithm is developed to provide additional information under the assumption that the altitude of the vehicle is approximately a constant, which is deemed appropriate for urban applications. Furthermore, for land vehicles, it may be assumed that the speed of the vehicle is not significantly varying so that the constraint-filtering method with soft constraint may be applied. The integration of these methods yields a successful algorithm to manage the ill-conditioned positioning problem if the number of visible satellites drops to below 4. From both static and dynamic experimental results, it is shown that the proposed methodology indeed gives rise to an effective scheme that can sustain the service for a few minutes, even if there is no satellite in view at all.