Method for detecting leakage of full-capacity LNG storage tank by acoustic emission

A method for detecting leakage of a full-capacity liquefied natural gas (LNG) storage tank by acoustic emission, comprising:

• suspending a detection surface of an acoustic sensor, detecting an amplitude of system noise by an acoustic emission machine connected to the acoustic sensor, and detecting a signal acquisition threshold;
• mounting the acoustic sensor on an outer side of an outer wall of a storage tank, and acquiring an amplitude of ambient noise based on the signal acquisition threshold;
• exciting an acoustic signal at a distance of 0.1 m and a distance of x m from the acoustic sensor by an analog sound source, and acquiring, by the acoustic sensor, an amplitude of the acoustic signal excited by the analog sound source at the distance of 0.1 m from the acoustic sensor and an amplitude of the acoustic signal excited by the analog sound source at the distance of x m from the acoustic sensor, wherein x represents a thickness of the outer wall of the storage tank, in m;
• calculating, based on the amplitude of the acoustic signal excited by the analog sound source at the distance of 0.1 m from the acoustic sensor and the amplitude of the acoustic signal excited by the analog sound source at the distance of x m from the acoustic sensor, an attenuation coefficient of an acoustic signal passing through the outer wall of the storage tank;
• determining a maximum detection range of the acoustic sensor based on the amplitude of the ambient noise and the attenuation coefficient;
• and
• continuously moving the acoustic sensor on the outer wall of the storage tank in a step smaller than the maximum detection range, to perform an LNG leakage detection.