Research On Acoustic Detection Of Gas Valve Leakage In Petrochemical Plant

The valve is widely used in petrochemical enterprises, and sets across all the important position, it is mainly used to control the fluid in the pipeline, and ensure the normal operation of the device. Due to the rapid development of equipment technology in the petrochemical industry, the application of the valve is also becoming more frequent, and fluid medium has high temperature and high pressure, inflammable, explosive, corrosive and other characteristics, which is more likely to lead to frequent internal leakage of the valve, therefore, the safety performance of the valve is also put forward more stringent requirements, the tiny leakage can lead to unexpected disaster. Internal leakage of the valve is not easy to be found, and this makes it a great potential safety hazard for the production process. The internal leakage will result in products impure for light, and will pollute the environment and cause major accidents such as fire and explosion for serious, it will always threaten the safety of human and social. Therefore, it is very important to realize the on-line monitoring and the quantitative diagnosis technology research of the valve internal leakage, and it has the very important engineering significance and the widespread application prospect.In this paper, the pneumatic acoustics、Acoustic emission technology theory, numerical simulation and experimental research are combined to analyze the mechanism of the internal leakage acoustic emission source in the valve, a variety of acoustic emission signal analysis methods are used to extract effective leakage signal and study the characteristic law, draw the qualitative and quantitative diagnosis method, and develop the field applied valve internal leakage diagnosis system.According to the simulation on the flow field of gas valve, the mechanism of internal leakage acoustic emission source is understood, as the fluid sprays through the narrow leakage hole, multiphase turbulent jet flow field is formed in the downstream, and the acoustic emission signal is generated, the velocity field and pressure field distribution are analyzed, and the optimal sampling position of the signal is judged according to the field analysis and field condition of the valve. Building the experimental platform of gas valve leakage detection, in-depth study of the valve type, leakage form, pressure difference between upstream and downstream and other factors on the impact of internal leakage signal, according to the amplitude difference of the upstream and downstream of the valve, the characteristics of signal energy and frequency domain, three kinds of methods for qualitative detection are proposed, for an internal leak detection, the comprehensive use of a variety of methods will get more accurate results. Fitting the characteristic parameter average signal level(ASL) and the logarithm of leakage rate and the formula coefficient is determined, it is concluded that the application range of diagnostic formula is more accurate when the leakage rate is above 18L/min, and the fitting similarity is more than 0.99, and the internal leakage diagnosis formula provide the basis for the production of the diagnosis software, the software sets signal acquisition, analysis, processing and internal leakage rate diagnosis, and internal leakage level judgment at an organic whole, through the verification, the diagnosis system has a higher sensitivity and accuracy, and easy to operate, it can be directly used to achieve the purpose of diagnosing the internal leakage in field application..