Research On Detection Technology Of Built-in Acoustic Emission Sensor In Storage Tank

In the service of atmospheric tank in China,the corrosion of the base plate and even perforation leakage are often caused by the corrosion of internal medium,internal liquid level pressure and foundation inclination.The safety of the tank bottom plate can be evaluated by acoustic emission detection technology.Acoustic emission detection technology can determine the corrosion severity and location of the bottom plate by collecting the acoustic emission signals from the bottom plate without stopping production.It is convenient and fast,and has gradually become an important method for on-line detection of tank floor.However,the signal generated by corrosion and leakage of tank floor is often low amplitude signal,which has been attenuated greatly when it is transmitted to the outer wall sensor.Traditional detection method by installing sensor outside the wall is difficult to receive acoustic emission signal in the center area of tank bottom plate,which reduces the accuracy of Online detection and evaluation results of tank.This paper first studies the causes of tank floor defects,analyzes the mechanism and strength of hydrogen evolution corrosion,oxygen absorption corrosion and leakage signal.Then a multifunctional underwater acoustic emission detection device is designed,which can carry sensors into the tank for detection,mechanical expansion in the tank,collection of thickness measurement and underwater real-time positioning.The device structure design is reasonable and scientific,which increases the detection range of the location of the tank floor area.Secondly,the joint testing and comparison experiment is carried out.The leakage of tank bottom plate is simulated by three methods.The leakage value of tank bottom plate is collected and compared.It is verified that the sensor built in the tank has higher sensitivity to the acoustic emission signal generated by the bottom plate,especially for the defects in the center of the tank floor,The received acoustic emission signal is better than the external sensor array,and the low amplitude signal which is difficult to collect by the external sensor can be collected by the internal sensor.Finally,the paper proposes that the value of the present is 60 ° The four sided shape positioning algorithm and the internal and external geometric array algorithm improve the positioning accuracy.The results show that the joint array can improve the accuracy of the defect location of the tank floor.Through grid division of the tank floor detection area,the external array,internal array and internal and external combined array are used to detect the whole area of the tank floor on-line,and the experimental verification of the relevant positioning algorithm is carried out.The results of this paper provide a safe and efficient and reliable technical means for improving the accuracy of corrosion detection of tank bottom plate.