Study On Pipeline Defect Characteristics Of Different Magnetic Circuit Characteristics In Pipeline Leakage

Nearly half a century,as the national economy level and equipment manufacturing productivity significantly increased,oil,natural gas,and other countries the importance of strategic energy day by day,the energy security of the problems of long distance pipeline transportation should not be ignored.But,our country’s energy transport pipe line have different specifications,long in service life,and the distribution is complex and long transport distance,connecting the characteristics of long time for pipeline detection efficiency and safety of the test of considerable.In many kinds of pipeline defect detection methods,magnetic flux leakage detection has its outstanding advantages in efficiency,safety and cost.In magnetic flux leakage detection device,the main axial excitation is given priority to with permanent magnet excitation mode,there are in the process of excitation of the magnetic circuit design and optimization as well as the geometric dimension of permanent magnet,the magnetization energy permanent magnet between the pipe and material properties such as problems,to solve these problems to improve the efficiency of the magnetic flux leakage detection and reduce the test cost has certain significance.For permanent magnet magnetic circuit of the magnetic flux leakage detection,the problem of inaccurate,optimization and simulation model based on the principle of magnetic flux leakage detection and Maxwell’s equations for analyzing mathematical model of magnetic circuit and permanent magnet magnetization characteristics of magnetic circuit and its influencing factors;Proposes a simulation model with dc electromagnet as the excitation source,from the perspective of engineering electromagnetic field analysis of magnetic circuit of electromagnetic field model is established,through many physical field analysis software COMSOL finite element method,respectively,set up with the same geometric parameters,the same excitation effect,study different pipeline magnetic circuit characteristics of magnetic circuit characteristics of pipeline defects and special parts,electromagnetic excitation model and explore the relationship and difference between permanent magnet excitation model.Used in the engineering application of pipeline magnetic flux leakage testing device for dragging experiment,the characteristics of different magnetic circuit of pipeline defects and special parts,compared with permanent magnet magnetic circuit simulation model with the experimental data,the magnetic circuit of electromagnetic simulation model with the experimental data,analyzing the characteristics of the magnetic induction intensity distribution,from the Angle of the experiment verify the accuracy of the electromagnetic field simulation model.The results show that,under the same model size,the electromagnetic excitation and permanent magnet excitation have the same magnetization effect.For different magnetic circuit characteristics shown by the characteristics of the magnetic flux density curve,and compared with the simulation model of permanent magnetic field,electromagnetic field simulation model with the same ideological trend and the results more in line with the drag experimental data,proved from the perspective of the electromagnetic field to analyze the feasibility of the permanent magnetic circuit;According to the theoretical calculation,there is a linear relation between electromagnetic excitation simulation model and permanent magnet excitation device in engineering.An accurate simulation model of magnetic flux leakage is established from the Angle of electromagnetic field.It is of practical engineering significance to analyze the design optimization problem of permanent magnet magnetic circuit,improve the detection accuracy.