A leakage particle–wall impingement based vibro-acoustic characterization of the leaked sand–gas pipe flow

Solid particle leakage detection in double-wall pipes is industrially important, especially in chemical and petroleum engineering. Here, we developed vibration and acoustic sensor approaches for the characterization and comparative study of the applicability of leakage sand particle detection from the flow of gas pipes. A specific wideband vibration sensor and pressure-field microphone were selected to identify the vibro-acoustic characteristics within 50 kHz of the particle leakage. The vibro-acoustic time-behaviours and characteristic frequencies of particle leakage were observed by the time-frequency method. The leakage gas flow noise was verified by coherence analysis and minimized by a digital bandpass and band-elimination filter. Corresponding experiments were performed, and good agreement was found between the release pressures (0.1–0.3 MPa) with different leak sizes (0–8 mm) under different sand masses (120 μm) and vibro-acoustic Root-Mean-Square (RMS) levels. In the comparison of the two methods, the vibration method has a better frequency response for the leakage flow and is good for identifying whether there are particle leaks. The acoustic method has a time behaviour response and is good for establishing the relationship between the particle mass and signals. In addition, the acoustic method has frequency shift features with a better signal to noise ratio. The acoustic method lays the foundation for future work of more complex leakage detection combining the advantages of vibration and the acoustic method.