600MW汽轮发电机组励磁机振动故障的诊断及处理

针对某电厂600MW机组进行通流改造后励磁机转子产生不稳定强迫振动的问题,描述了产生剧烈振动的现象及特点,对产生不稳定强迫振动的原因进行了分析并提出解决办法,现场通过降低励磁机轴承标高及现场高速动平衡处理后,消除了励磁机转子振动问题,机组恢复正常运行状态。     

某250MW水电机组振动区划分及AGC避振方法应用

水电厂自动发电控制(AGC)的投入对机组的安全稳定运行造成一定影响,通过划分机组振动区能够有效提高AGC的避振运行。为此,采用真机试验方法对250 MW混流式机组开展不同水头下的稳定性试验,将运行区域划分为禁运区、不推荐运行区、推荐运行区,并对AGC运行过程中的多种避振运行问题进行优化处理,包括机组有功梯度调节限值的设置、实时计算并上报调度机组联合振动区、给定有功负荷落在不推荐运行区等。结果表明,振动区的划分不仅有利于保障机组的安全稳定运行,且为调度中心的负荷调度调整提供了参考。     

可倾轴承损坏引发的燃气轮发电机组 低频振动故障分析

某台大型单轴式燃气轮发电机组发生了不稳定振动。带负荷运行时,#4、#5轴承振动出现随机性大幅波动。对机组带负荷运行状态下的振动进行了测试。试验发现,振动与润滑油温之间有一定关系,振动波动时轴系轨迹紊乱,轴颈中心位置不稳定,振动信号中出现了13 Hz左右的低频分量。振动波动时,50Hz工频分量稳定。轴振波动时瓦振没有波动。对机组上发生的这类少见故障的原因进行了分析。指出可倾轴承损坏是不稳定振动的主要原因。停机后对轴承进行了检修,解决了机组上发生的振动故障。     

某抽水蓄能电站3F机组摆度偏大问题分析与处理

某抽水蓄能电站3F机组存在上、下导持续升高且超标现象,影响机组的安全稳定运行。本文对该问题进行现场检查及分析,对松动的磁极键进行打紧,并对存在的转子不平衡问题进行了动平衡配重试验,处理后机组的运行数据显示摆度和振动测值正常,机组恢复了稳定运行状态。     

基于工程实践的汽轮发电机组不稳定振动的研究

统计分析了十年来30台次的大型汽轮发电机组发生的不稳定振动故障的实例,对发生不稳定振动故障来源阶段及形式进行了统计分析,同时统计分析了引起机组不稳定振动故障的主要原因占比,结合现场实际案例阐述了机组发生不稳定振动故障所表现的特征及处理措施,为大型汽轮发电机组的安全运行提供了技术参考与依据。     

国产300MW汽轮机4号轴承不稳定振动问题研究

在对国产300MW汽轮机低压转子与轴承系统的结构特点分析基础上,结合大量现场试验研究,分析了300MW汽轮机4号轴承不稳定振动的特点。主要从真空变化、轴封蒸汽参数变化以及负荷、轴承标高等的变化对4号轴承不稳定振动的影响加以分析,总结了引起4号轴承不稳定振动的原因,并提出了控制4号轴承不稳定振动的运行与维护措施。     

燃气轮机过渡态的振动分析

舰用燃气轮机在启动停机或升速降速过程中,其工作状态与稳定工况有很大差别,其振动现象和规律也有很大差异。有时,机组在启动中出现叶片磨损或轴承损坏等故障,故障后可能引起严重的振动损坏。因此,测量和分析燃气轮机过渡态的振动特性,寻找其规律,为排除故障,保证机组可靠运行是十分必要的。由于燃气轮机的结构复杂及其运行特点所决定,它的振动现象也是一个复杂的过程。所有振动频率分量均不稳定,振幅具有随机性,尤其在过渡态机组的振动现象可谓瞬息万变。因此,用随机振动理论来研究燃气轮机的振动问题是适宜的。我们应用快速付里叶分析仪     

半联轴器外伸接套轴线偏差对轴径振动的影响

汽轮机轴颈振动超差是汽轮机试运行及运行中常见的问题,也直接影响着汽轮机组的安全稳定运行。本文主要针对T72A8汽轮机单机试车过程中出现轴颈振动数值过大,现场分析产生轴颈振动超差的原因,提出解决方案,以及处理后的振动数值,希望能对维护运行技术人员有一定的参考和帮助。     

油碳化物积聚诱发的不稳定振动特征及诊断

某燃气轮发电机组运行中出现了比较严重的不稳定振动,影响了机组的安全运行.通过对机组振动的测试与分析,查明轴承泄漏润滑油在高温环境下所形成的碳化物积聚是导致振动的主要原因,清除碳化物后振动得以消除.     

混流式水轮机机组运行稳定性区域检测

水电机组在带负荷运行过程中,水力机械振动会引起机组不稳定运行。为了掌握水电厂机组运行稳定性情况,需对其进行变负荷真机试验。在某水电厂3#混流式水轮机机组空载、满负荷等13种运行工况下进行试验,现场实测各运行工况下振动、摆度和压力脉动的变化,并分析机组运行稳定性及存在的缺陷。结果表明,从机组振动、摆度、压力脉动数据和现场评估综合分析,该试验机组稳定运行区间为25～40 MW。研究为机组安全、稳定运行提供了一定的技术依据。     

Unerroric of control of mutual compliance of the efficiency of hydrogen engines of unmanned vehicles in the conditions of mass production

The issues related to the reliability of hydrogen engines of unmanned vehicles and increasing the efficiency of using hydrogen as fuel when using the method of its production during the decomposition of hydrogen-containing molecules of liquid-phase organic compounds in a plasma discharge under the action of intense ultrasonic exposure are considered. Experiments have shown that as a result of decomposition in the acoustoplasma discharge of liquid hydrocarbons, solid-phase carbon-containing products are formed, chemical transformations occur in the liquid phase and hydrogen-containing combustible gas is formed. Hydrogen-containing gas can be used as fuel immediately after synthesis, i.e. it does not require separation, since in addition to hydrogen it contains only impurities of CO₂ and water vapor. The purpose of the study is to formalize the basic conditions for tightening the control of mutual compliance with the efficiency of hydrogen engines of the same series in the conditions of their mass production. Methods of mathematical statistics and hardware-software modeling were used in the study. The term “unerroric of quality mutual compliance control” is introduced to describe a set of hardware and software tools for such control. The principle of in-depth testing of the technical condition of such engines of one series is described in a multidimensional formulation of the quality control problem for three of their operating parameters at once. The conditions for increasing the mutual correspondence of the measured values of such parameters in the conditions of serial production of hydrogen engines are formalized.     

小型锅炉烟尘测试时锅炉出力的计算

锅炉烟尘测试时,必须对锅炉出力进行测试。但监测中,许多小型锅炉往往不具备相关的计量装置和仪表,为解决这一问题,文章提出了用烟气量和空气过剩系数来计算锅炉的出力的公式,在实际使用中,该方法简单易行,其结果和实测值具有很好的一致怀。     

中国煤炭地下气化技术的发展

本文综述了煤炭地下汽化技术的国内外发展现状,对我国“长通道、大断面”煤炭地下气化新工艺给予了技术经济评述,并提出了发展煤炭地下汽化技术的政策建议。     

Review of theory of distortion and disintegration of liquid streams

Linear and nonlinear analyses of the instabilities and distortion of liquid streams injected into a gaseous media are discussed. The various fundamental mechanisms and the predictive capabilities for the distortions are emphasized. Round jets, planar sheets, annular sheets, and conical sheets are discussed in detail. The balance between capillary and inertial forces is primarily examined. The method for simplifying the analyses in the case of thin liquid sheets is discussed. The capabilities for representing the droplet size distribution that follows the stream disintegration are outlined.     

MgO膨胀剂细度对MgO水化和水泥浆体膨胀的影响

基于《水工混凝土掺用氧化镁技术规范》中的Ⅰ型氧化镁（MgO）,研究了该型MgO膨胀剂（MEA）细度对掺粉煤灰水泥浆体膨胀性能的影响。即采用X射线衍射分析(XRD)及同步热分析（TG DSC）分析了掺MEA水泥浆体中MgO的水化性。结果表明,养护温度相同时,MEA的细度对水泥浆体内MEA中MgO的水化和水泥浆体的膨胀无显著影响,产生的膨胀均能补偿水泥浆体的收缩;MEA的细度可从试验设计采用的45 μm筛筛余15%左右增加到30%左右,这将有利于MEA生产企业的节能降耗。     

机车车轮多轴疲劳强度安全评定的研究

使用ANSYS8.0软件对高速列车车轮进行了三维有限元分析,计算出车轮在直线、曲线和道岔条件下牵引、制动共6种工况时孔边薄弱部位的应力,分别通过Mises等效平均应力方法、Sines平均主应力方法和应力分量中考虑平均应力方法计算出应力在极值位置时的等效应力幅、等效平均应力,从而进一步算出车轮的安全系数,对其疲劳强度进行评定,并对3种方法进行了比较研究。     

Constructal optimization of the geometry of an array of micro-channels

This paper documents the geometric optimization of an array of circular and non-circular ducts. The optimization was carried out numerically using finite volume method. As optimal dimensions were independent of the array configuration, the numerical simulation was performed on a unit cell. Numerical optimization for circular, square and isosceles right triangle cross-sections of channels was performed. Based on the results of this investigation, some correlations were proposed to predict the optimal hydraulic diameter and dimensionless heat transfer per unit volume. In addition to examining the effect of pressure drop on these parameters, it was showed that among the different geometries of this study, square cross-section has the most efficiency for a given volume. The numerical results of the present study were compared with approximate results reported in the literature which a good agreement was observed.     

Heat of vaporization of mixtures

General expressions for the heat of vaporization of mixtures at constant pressure; at constant temperature; and at constant pressure, temperature, and composition are proposed. The last one is related to the liquid-vapor interface where steady vaporization or condensation is taking place. Numerical examples by the proposed expressions are shown for binary mixtures of HCFC22(R22) and (HCFC123(R123) © 1997 Scripta Technica, Inc. Heat Trans Jpn Res, 25(1): 12–24, 1996     

固体热辐射Yong性能分析

本文对漫灰均温物体在常物性条件下对外辐射传热的Ｙｏｎｇ值计算建立了数学模型。通过与物体内能Ｙｏｎｇ公式的数值计算比较,得出了辐射能量的Ｙｏｎｇ值不大于内能Ｙｏｎｇ值的结论。从初步的热射Ｙｏｎｇ值计算公式发现。Ｙｏｎｇ与物体表面辐射率有关。     

Measurements of concentration distribution of hydrogen jet using deflection of center of the laser spot

The main purpose of this work is to propose a new method to evaluate the concentration distribution of the hydrogen jet by using a He–Ne laser through the jet. This research attempts to apply the expression of concentration Gaussian distribution, the refraction formula of inhomogeneous refractive index medium, and the concentration inversion function to disclose the displacement of the center of the laser spot at different heights in the gas jet. The spot images of the laser beam passing through the gas jet at three vertical heights z = 10d, 20d, 30d, and different radial positions are obtained. The radial spatial asymmetry of the gas jet is also found in the experiment. Finally, the calculated concentration distribution curve and the fluent simulation curve, it is found that the two results are very similar. Our findings show that the error between the concentration distribution of this method and the simulated concentration distribution reaches 2.43%.