Research On Visual Diagnosis Technology Of Valve Leakage Fault Based On Acoustic Emission Detection Method

Valve leakage fault is one kind of frequent faults in power stations and chemicalindustry enterprises. At present, most of the valve leakage detection methods havesome certain limitations, so leakage information is difficult to be reflected accurately.Consequently, there is important engineering application value for visualizationdiagnosis of valve leakage fault.In order to achieve the visual detection for valve leakage faults, the article adoptsthe combine method of theory and experiment, leakage visualization technology ofvalve leakage is implemented from two aspects, leakage modes research and leakagerate research, combined with LabVIEW software.First, the flow field and energy calculation method at leakage holes of the typicalleakage modes are analyzed, the valve leakage state with different leakage modes isstudied in the simulative experiment, and the wavelet packet technology is also appliedto analyzing the valve leakage acoustic emission signal, then variation laws of valveleakage acoustic emission energy with different leakage modes are acquired. Researchresults show that: the acoustic emission signal energy distribution in certain frequencyband of different leakage modes has obvious regularity. The characteristic frequencybands are pined down by a lot of experimental data, and the quantitative diagnose rulesof valve leakage fault modes are established.Then, the fluid flow condition in valve leakage process is analyzed; valve leaksource analysis model is established. Also the theoretical relationship between valveleakage rate and acoustic emission signal RMS (Root-Mean-Square), fluid parametersand valve parameters is deduced according to sound features of the dynamic fluidsource, the three valve empirical formulas of valve leakage rate are obtained by fittinga lot of experimental data, through experimental research on the fault simulation testbench. The quantitative detection of valve leakage is implemented.Finally, the paper develops a set of visual detection system of valve leakage faultbased on the LabVIEW software development platform, of which, the3-d model isestablished based on Solidworks, and is imported in LabVIEW software, visualization for leakage diagnosis results is achieved according to the theory of mapping data;visualization display for leakage rate is achieved through empirical formula of leakagerate as the theoretical support and the display controls on LabVIEW front panel such asthe liquid column、the Boolean and so on. Experiments prove that detection of leakagemodes is accurate and reliable, detection error of leakage rate is less than10%, and thesystem is quick-witted, diagnostic results of which is intuitive and clear. Reference forthe treatment of valve leakage is provided.