Mixed multiple‐variable modelling of acoustic emission signals for valve internal leakage detection

Abstract

Theoretical analysis and experimental data show that the acoustic emission (AE) technology can detect the internal leakage state of the valve online. One of its key technologies is to determine the relationship between the characteristic of valve internal leakage AE signal (VILAES) and leakage rate and various parameters. However, most of the currently established models are a single-variable model. In addition, the repeated and verification experiments are rarely introduced, and most experiments are conducted under a large leakage rate. To this end, the mixed multiple-variable model is built to describe the relationship between the characteristics of VILAES and leakage rates, pressures, valve calibres and flow coefficients for the same type of valve. In the experiments, two rounds of experiments were performed for the same valve; then, a round of experiments was carried out after moving the sensor, and two rounds of experiments were conducted for two valves with the same parameters. In modelling, the VILAES is filtered first, and then the characteristics of the filtered signal are calculated. The mixed multiple-variable model is established by the leastsquares support vector machine. The results show that the mixed multiple-variable model could realise online internal leakage for valves with different calibres and flow coefficients under different pressures.

Experimental analysis of the effect of sealing surface pitting defects on valve sealing performance

“…When performing the D test, the degree of deformation of the valve plate's sealing surface determines how fit the valve plate and seat's sealing surfaces are, which in turn determines the leakage volume. The stem thrust and media pressure for medium-and large-size wedge gate valves are insufficient to flatten the deformation of the sealing surface [18][19][20], and the valve plate size is large and rigid. As a result, the leakage channel size between the sealing surface does not significantly change under each media pressure, and the leakage volume also does not significantly differ under each media pressure.…”