Study of the health of an operating industrial valve by means of the continuously acoustic emission measurement

Abstract

A continuous evaluation of valve was set up to detect leak flows occurring during a critical operating phase of an industrial facility ' the pressure rise of a valve circuit. Leak or passing flows generate Acoustic Emissions (AE) which we measured, in a non-intrusive way, by means of piezo-electric sensors[1] placed on the analysed valve. Simultaneously to AE measurements, the upstream relative pressure was acquired. To do this, we developed an ad-hoc measuring bench to operate at high temperatures (up to 540 °C) and to acquire data, continuously and simultaneously. The experiment took place over a period of 11 days. The upstream pressure and temperature of the fluid (water vapor) increased from around 0 bar to 70 bar and from around 100 to 400°C, respectively. At the valve downstream, air was at atmospheric pressure. Data processing using multiresolution analysis to denoise AE signals was developed and tested on our experimental data. The AE signal being regular, our denoising algorithm is based on the elimination of non-regular phenomena from a time-scale analysis. From the evolution of AE statistical parameters, which are correlated to the flow rate[1], we detected the occurrence of valve opening, damage or maladjustment in an industrial environment.