大型空冷机组真空泄漏诊断及对策

根据多年火电机组真空泄漏检测经验,分析大型空冷机组真空泄漏产生的原因,通过研究氦质谱检测技术和超声波检测技术,归纳总结出大型空冷机组真空泄漏诊断技术,并在大型空冷机组应用,消除真空系统泄漏,确保大型空冷机组安全经济运行,同时提出防止真空系统泄漏应该采取的措施.     

基于声发射的真空泄漏在线检测技术研究

真空泄漏是气体动力系统运行过程中的常见故障,传统的氦质谱检漏无法实现对真空泄漏的在线检测。本文利用声发射技术阐述了基于声发射信号的真空泄漏在线检测原理,通过真空泄漏声发射检测模拟试验,并利用参数特征分析法和平均频谱分析法对不同泄漏孔径下产生的声发射信号的特征进行了研究,得到了相应的小波包归一化频带能量分布特征。研究结果表明,真空泵运行的平均时域信号频带在20kHz以下,气体泄漏激发出大量的高频声发射信号,泄漏信号参数特征值与泄漏孔径的大小密切相关,泄漏信号的归一化能量分布一致性较好。声发射技术对于真空泄漏的在线检测及泄漏量评价等有实际意义。     

超声波流量法用于输油管道泄漏监测系统的研究

把超声波流量法应用到管道泄漏检测中,可解决单独使用负压波检测技术时误报率高、泄漏发现不及时等问题,实现输油管道泄漏的精确实时检测。使用虚拟仪器平台LabVIEW建立了管道泄漏监测系统。为提高超声波流量计精度,采用混沌现象中间歇混沌的特性检测出带有强噪声的微弱超声信号。实现输油管道的高精度的流量测量。     

S7-300PLC的盘管泄漏检测系统设计

针对化工生产中盘管泄漏检测与控制的要求,结合自动化控制技术、智能传感技术、现场总线技术等,设计了一套基于西门子S7-300PLC的化工盘管泄漏自动检测系统.详细介绍了该系统的硬件组成、工作原理和软件实现.该系统同时采用"流量差"和"压力差"两种检测方法对盘管泄漏进行检测,并采用PLC实现对盘管泄漏的在线检测和全自动报警控制;再加上控制方式多样,从而使得这一套检测系统可以适应不同情况下的控制需要.     

基于FPGA和DSP的超声波检测系统设计

针对目前机车车辆模拟式超声波检测仪器的不足,设计了一种基于FPGA和DSP的数字式超声波检测系统.整个系统由信号预处理模块、高速AD转换器和数据采集处理等模块构成,解决了超声波检测中的高速数据采集和处理的关键问题,实现了超声波信号的检测、处理和显示.试验结果表明,由于采用高速数字信号处理技术,不仅提高了检测系统的精度,而且系统运行稳定可靠,达到超声波信号检测要求.     

空间环境下航天器部件密封性能评价方法研究

从航天器密封部件的密封种类和泄漏原理,特别是橡胶密封圈的泄漏原理出发,分析了经高真空、高低温、空间辐照等空间环境对航天器密封性能的影响,给出了采用泄漏检测技术作为密封性能评价的方法。重点介绍了基于现有漏率性能评价方法而研制的几种航天器部件密封性能评价装置以及在现有评价装置上开展的部分航天器部件密封性能试验及研究情况。     

氦质谱压力真空检漏法在高压容器检测中的优化分析

本文介绍了氦质谱压力真空检漏方法在高压容器泄漏检测中的优化分析。通过给氦质谱压力真空检漏法的集气室充气工装增加辅助抽气室,避免高压条件下充气工装泄漏造成的检漏系统本底信号过高影响,提高了氦质谱压力真空检漏方法在高压容器检测中的灵敏度和检测数据的准确性,拓展了氦质谱压力真空检漏方法的适用范围。     

云冈电厂空冷机组高真空运行研究

本文以直接空冷机组夏季高真空运行为研究对象,结合现场改造和运行经验,从以下两个方面对如何使机组提高运行真空进行了研究和分析：一是如何使机组保持运行真空,由于直接空冷机组真空系统庞大,泄漏原因复杂;二是提出了强化传热、系统改造等不同技术路线对直接空冷机组的真空散热系统进行改进,结合云冈电厂实际的技术改造项目进行说明分析。     

混合干涉型分布式光纤天然气管道泄漏检测及定位方法研究

介绍了一种基于马赫-曾德尔和萨格纳克混合干涉仪原理的分布式光纤天然气管道泄漏检测系统.阐述了检测系统的检测原理及泄漏定位方法,在泄漏点距法拉第旋转镜为6 032m处进行了气体管道泄漏检测实验并重复做了20次试验,测试了传感光纤与泄漏点不同夹角对检测系统性能的影响.实验结果表明,该系统可以检测出管道内气体压力为0.3MPa、泄漏孔径为2.5mm的微小泄漏信号并进行定位,平均相对定位误差为1.29%.在40mm的管道外径下,传感光纤与泄漏点夹角在0～180°范围内,检测系统均能检测出泄漏信号并进行定位.     

基于混沌-BP神经网络的真空泄漏声发射在线检测技术

随着空间科学技术的不断发展,人们进行的空间活动日益增多。与此同时,空间碎片的数量也随之急剧增多,这使得在轨航天器遭受空间碎片等动能颗粒撞击可能性不断增加,航天器发生密封结构泄漏的可能性越来越大。航天器泄漏不仅会造成航天活动的失败,更会威胁航天员的生命安全,因此,在轨航天器真空泄漏声发射在线检测技术研究具有十分重要的意义。本文以声发射技术为基础,利用精细平均功率谱分析法对不同泄漏孔径下产生的声发射信号特征进行提取分析,并与改进的混沌-BP神经网络模式识方法相结合实现对信号进行分类,从而实现泄漏检测以及漏孔大小评估。通过真空泄漏声发射检测实验验证,本方法最小可检0.4 mm直径的漏孔,满足在轨航天器微弱泄漏检测的需求。     

Industrial leak testing of dangerous goods packagings

The Dangerous Goods Regulations currently do not include limit leakage rates or sensitivity requirements for industrial leak testing procedures that are equivalent to the bubble test, which is the prescribed test method for design type testing of dangerous goods packagings. During series production of such packagings, various methods are used, which often do not meet the requirements of the bubble test with regard to important criteria. Sensitivity, flow direction, pressure level and automatability are particularly important factors when selecting a suitable industrial leak testing method. The following methods are in principle both suitable and equally effective as the bubble test: pressure rise test (vacuum chamber), ultrasonic bubble leak detection and gas detection methods (pressure technique by accumulation and vacuum chamber technique). To ensure a uniform test level during design type testing and production line leak testing and therefore a comparable safety level as required by the Dangerous Goods Regulations, it is necessary to include a more precise specification in these regulations. This requires, on the one hand, information about the sensitivity of the bubble test and, on the other hand, the inclusion of a list of suitable, equally effective industrial test methods with their specific boundary conditions.     

真空混合漏孔示漏气体的延迟和保持特性研究

真空混合漏孔 ,如漏孔通道内含有空腔、毛细管道等 ,示漏气体除存在超长反应时间外 ,还存在超长的延迟时间和保持时间。只有经该延迟时间后 ,检漏仪才能探得信号。为满足真空元件在生产中的快速检漏的要求 ,又避免常规质谱检漏法漏检混合漏孔的可能性 ,在真空室内对检漏元件集体充氦 ,然后在保持期内逐个检测氦气浓度来判断有无混合漏孔 ;也可用质谱计比较残余气质谱图中空气成分来确定     

基于频谱分析的压缩空气泄漏直射和反射超声的识别

介绍了气动系统中压缩空气泄漏超声检测的原理,分析了由反射超声信号导致的错误检测问题,并提出通过识别反射超声信号的方法来解决此问题;对直射和反射超声信号进行测量实验研究,发现并分析了直射和反射超声信号在频谱图形状上存在的明显区别;通过设计识别算法,得到可识别反射超声信号的反射特征系数 (Reflectance Characteristic Coefficient,RCC);经实例计算发现：直射超声信号的RCC值在100以下,反射超声信号的RCC值在200以上。该结果对压缩空气泄漏检测中有效的识别出反射超声信号、避免由反射超声波导致的检测错误具有重要的实用价值。     

High sensitivity leak testing for critical nuclear components

Quality Assurance on leak tightness performance of systems and components that handle hazardous, toxic/radioactive fluids is to be ensured through a well chosen leak testing method. It is very much essential for components and systems used in such applications to be subjected to high sensitive leak testing methods capable of detection of leaks of the order of 10⁻¹¹ Pa.m³/sec. due to the fact that a minutest leakage to the environment is likely to pose serious consequences. The choice of a particular leak testing method and technique depends on the degree of leak tightness required and the service requirements of the components. Mass spectrometer leak detection method is the only technique which possesses matching sensitivity requirements for the purpose of ensuring the leak tightness of this magnitude, thus well suited for testing of critical components required for Fast Reactor, Cryogenic systems, ultrahigh and high vacuum applications etc. Large number of components required for such applications have been subjected to a very stringent leak tightness requirements with a sensitivity of the order of 10⁻¹³ Pa.cu.m/sec. This paper outlines the approach, planning and execution of helium leak testing of a few critical components with varying complexities. The details of the difficulties experienced, particularly in attaining higher vacuum and suggestions to achieve highest sensitivity are also discussed.     

Measurement of helium leaks 10 times better than the sensitivity of a mass spectrometer leak detector

The actual limit of helium leak detection is given by the highest sensitivity to helium of a mass spectrometer leak detector and can be considered to be 10⁻¹⁰ atm cc/sec. The output of such a leak detector is strongly influenced by the vacuum created at the height of the spectrometer tube. In this paper a method is proposed which permits the range of leak measurements to be extended by a factor of 10⁻⁵ over the actual limit of mass spectrometer leak measurements. The method is based on the accumulation of a leak, compared to the accumulation of a background over the same time. The rather complex manipulations are explained and justified so that the reader of the paper becomes familiar with this technique.     

真空热处理炉现场检漏的理论分析法

本文以我公司首台进口的油淬气冷多用真空热处理炉的现场检漏分析为例,介绍了在没有专用检漏仪器的情况下,以理论分析判断为主的检漏方法,以及对真空热处理炉现场检漏的相关理论和注意事项进行了论述.     

固定流导法真空漏孔校准装置性能研究

固定流导法是通过已知流导小孔的气体与真空漏孔流出的气体用四极质谱计进行比较,从而得到漏孔漏率的一种极为精确的方法。小孔是采用机械、激光等方法加工制成,在分子流条件下,小孔流导为一常数。运用此方法,建立了一套真空检漏校准装置以进行量值传递工作。为了保证校准数据的准确可靠性,需对该套装置的不确定度进行分析与评定。     

Sensitivity of the Contra-Flow leak detector at high test pressures

The Contra-Flow leak detection technique consists of letting the tracer gas (helium) diffuse upstream through the high vacuum pump toward the mass spectrometer sensor. The test object can remain at relatively high total pressure, as high as the tolerable forepressure of the high vacuum pump. Because this environment is not in the molecular flow regime, the relationship of detection sensitivity to pump performance parameters is sufficiently different from those of conventional leak detectors to warrant an investigation. Comparative tests were made with both types of detectors over a wide range of test pressures using water vapour, air, nitrogen and argon to simulate various test object pressure conditions. The results reveal that at test pressures above approximately one pascal the Contra-Flow method provides at least ten times higher sensitivity. Exposure of the test object to mechanical pump oil vapour can be prevented by a continuous stream of a helium-free gas or by the use of zeolite traps. The latter do not absorb helium significantly but produce a great effect on the residual gas composition.     

四极质谱计在真空检漏中的应用

介绍了使用四极质谱计进行真空检漏的原理和方法,分别对超高和极高真空系统做了检漏实验研究，并取到了满意的结果。四极质谱计检漏有检漏仪检漏无法比拟的优点，适合在真空工程中推广应用。     

带腐蚀性物料的真空系统在线检漏方法研究

带腐蚀性物料的真空系统,往往对密封性要求严格。为了进行带腐蚀性物料的真空系统在线检漏而进行研究,分析可行的检漏方法,提出适用手段。通过分析,经过分级冷冻、物料处理及选用适合的检漏步骤,能够使氦质谱检漏仪满足负压检漏条件,从而使用喷氦法确定漏点位置,使用氦罩法获得准确的漏率。实际应用证明,该方法用于带腐蚀性物料的真空系统在线检漏,能够准确、有效的检测漏点位置及漏率。该研究为带腐蚀性物料的真空系统在线检漏提供了技术支持。