Research On Pipeline Leakage Detection Technology Based On FBG Pressure Sensing

With the rapid development of economy and the sustainable development process of industrialization,pipeline transportation has been widely used in various fields.In stark contrast to this,along with the growth of pipeline service cycles,pipeline leakage accidents have happened from time to time.For oil and gas pipelines,leakage of flammable materials not only wastes resources,but also leads to the environment pollutions.It may even threaten the lives and properties of surrounding people.Therefore,it would be huge practical significance to study the relevant theories and related technologies of oil and gas pipeline leak detection and localization.At present,in the field of pipeline leakage detection,most of the leakage detection methods have limitations,such as poor anti-interference ability and incapability of realizing distributed real-time detection,which results in the existing methods failing to completely meet the needs of the leakage detection.The fiber Bragg grating(FBG)sensing technology,which has advantages of small size,no electricity,antielectromagnetic interference,wavelength division multiplexing,high accuracy,and corrosion resistance,can effectively solve the above problems.Therefore,based on the FBG pressure sensor,the effect of this sensor applied in the field of pipeline leakage detection is studied.The main work includes the following aspects:(1)In view of the FBG pressure sensor at this stage can't meet the tightness and the requirement reliability of oil and gas pipeline leak detection,this paper designed and packaged a FBG pressure sensor which suitable for oil and gas pipeline pressure monitoring using and diaphragm and L-shaped cantilever beam as a sensitive structure.(2)Through theoretical analysis,the principle of sensitization and temperature compensation of the sensor is revealed,and the parameters of the sensor are selected by MATLAB.The finite element analysis is used to understand the static sensitivity and dynamic response characteristics of the sensor.The simulation results verify the validity of the theoretical model.In the simulation,it is found that the special mode of encapsulation can improve the natural frequency of the first order mode of the sensor.The sensor is packaged by means of laser welding and two-point packaging.The actual size of the sensor after the package is ?46×50 mm.The experimental results show that the pressure sensitivity of the sensor is 1185.621 pm/MPa in the range of 0-2 MPa,and the temperature compensation effect is good.(3)The sensor was used to build a static oil pipeline leak model,and the experimental scheme was determined.The oil pipeline leak test was carried out.The experimental data were analyzed and processed,and the error is also analyzed.When wavelet denoising was performed on the data,sym8 wavelet was selected as the wavelet basis for wavelet denoising,and the number of decompositions of the pressure signal was chosen as 6,and the denoising effect was found to be good.When wavelet analysis was used to determine the inflection point of the negative pressure wave,db4 wavelet is selected by multiple contrast experiments,the decomposition scale is selected to be 5,it can be found that the reconstructed signal of the detail layer can fully show the singularity of the original signal.The experimental results show that the average error of the model's leak location is 14.17%.Experiments show that the FBG pressure sensor can be effectively applied to pipeline leak detection.