Research On Acoustic Emission Technology And It's Engineering Application In Condition Monitoring Of Journal Bearings

Journal bearing is an important support component of shaft system of a turbo-generator set, the safe and stable operation of the whole unit is based on its well working condition. Therefore, there is a significant academic value and engineering guiding function to study the qualitative or quantitative relationship between Journal bearing condition and its acoustic emission signal, and then develop for bearing condition monitoring application technology to maintain the safe running of the equipment.The Journal bearing condition monitoring system which is based on AE technology is developed on LabVIEW software development platform. Through laboratory test and verify, the system's performance is sensitive, accurate and reliable, and easy to operate. And on the trend analysis about a continuous acoustic emission signal, it's better than PCI - type 2 acoustic emission detector which is produced by PAC.According to the working characteristics of Journal bearings, in this thesis, the qualitative relationship between the friction power loss and speed, oil temperature, oil pressure, bearing static load was established, and then proposed the Journal bearing of large turbo-generator set condition monitoring proposal which is based on AE technology. The Journal bearing condition monitoring system has been used for engineering application, and it has been used to monitor the Journal bearing'condition during startup of the 300MW and 600MW steam turbine unit. Analysis of the monitoring results found that when the film is thick, the AE signal is strong; when the film is thin, the AE signal is weak; when the film disappearance caused dry friction, there is a sharp increase of the AE signal; when the lubrication condition of Journal bearing is in serious deterioration, the AE signal will beat within large range. With the comparison of the vibration signal test systems, the Journal bearing AE monitoring system was high sensitivity and the monitoring results are accurate and reliable.Through in-depth comparison analysis with theory research and test results, we found the AE signal characteristic's variation with lubrication condition of Journal bearing, and it provides an important basis for real-time condition diagnosis of Journal bearing.