Design Of 3D Magnetic Flux Leakage Detection Sensor System For Oil And Gas Pipeline In Service

As an important tool for transporting oil and gas,pipeline plays an extremely important role in industrial production and economic construction,which is called "energy blood".Throughout the country,many crude oil pipelines,natural gas pipelines and product oil pipelines have been built and put into use.The safety problems of oil and gas pipelines are becoming more and more serious,and the safe operation of pipelines has also attracted people’s attention.With the extension of pipeline operation time and the increase of pipeline lines,the pipeline will appear wear,corrosion,accidental damage and other problems.The transportation of energy such as oil and gas is bound to be affected,which will cause all kinds of losses and serious risks.Therefore,it is particularly necessary to carry out regular inspection on oil and gas pipelines in service.At present,the detection technology of pipeline leakage is generally used.Aiming at the problems of low sensitivity,low detection accuracy and large volume of traditional magnetic leakage detector in pipeline,a highly integrated 3D magnetic leakage detection sensor system is proposed.The system has multiple Hall sensors in three directions,and has higher detection Accuracy,while detecting defects,can also identify internal and external defects.The main contents of this paper are as follows:Firstly,the theoretical basis of pipeline magnetic flux leakage internal detection technology is introduced,the formation mechanism of magnetic flux leakage field is studied,and the principle of magnetic flux leakage detection is explained.Through the establishment of three-dimensional simulation model of pipeline magnetic flux leakage field,the magnetic flux density nephogram and magnetic flux density curve of magnetic flux leakage field with or without defects are obtained.According to the obtained signal,whether the pipeline wall has defects can be judged,and whether it is internal or external defects can be further judged in the case of defects.This paper introduces the selection and placement of Hall sensor,describes each part of 3D MFL detection sensor system,and designs and manufactures 3D MFL detection sensor system.The theory of wavelet transform and the idea of threshold de-noising are introduced.The magnetic flux leakage signal is processed by using the 6-level decomposition of DB6 wavelet,and good results are obtained.Through regression analysis,the mathematical relationship between the characteristic quantity of defect size and MFL signal is obtained.A simple experimental platform was built to make artificial defects on the steel plate,and the three-dimensional magnetic flux leakage detection sensor system was used for the experiment.The results show that the average measurement error is 9.21%,and the signal-to-noise ratio can reach 43 db after denoising,which basically meets the expected requirements.The 3D MFL detection system is small in size and low in power consumption.Compared with the traditional MFL detector,it has improved the detection ability and accuracy.