The Research And Design Of Remote Field Eddy Current Electromagnetic Testing System For Pipeline Defects

Pipeline transportation of oil and gas is one of the major transport industries in our country and plays a crucial role in the economic development of our country.However,most of the oil and gas pipelines in service have been used for decades in our country,leading to the reduction of the pipeline safety factor,such phenomena as abrasion or leakage can cause huge economic loss,environmental pollution and even life-threatening.Therefore,the non-destructive testing of pipeline technology has great significance.The research of the pipeline detection probe is one of the important content of non-destructive testing technology,it is the premise of accurately judging the condition of the pipe wall,which has important practical significance.Based on the analysis of the research status of the far-field eddy current non-destructive testing technology at home and abroad,this thesis studies the far-field vortex nondestructive testing technology carefully and designs a complete set of far-field eddy current electromagnetic testing system,and do the defect detection experiment.Its main content includes the following three aspects:Firstly,aiming at the weak detection signal of typical far-field eddy current electromagnetic detection system,an enhanced harmonic resonance excitation coil is proposed.The unbalanced bridge method is used to achieve the resonance state,and the generated magnetic field is higher than that of the ordinary coil,thus improving the detection signal amplitude.The excitation coil is detailed theoretical studied.Then,the overall design scheme of the far-field eddy current detection system based on the kind of coil is proposed.Secondly,the principle of far-field eddy current detection technology is introduced in detail in this paper.Then the finite element simulation of the excitation coil and the whole detection system is carried out by ANSYS software.The results show that the magnetic field generated by the enhanced harmonic resonance coil is stronger than the normal coil and the feasibility of field eddy current testing.Then the various factors affecting the effect of detection probe are simulated,and the influence rule of these factors on the effect of far field eddy current detection is obtained,which provides the theoretical basis for the design of the latter detection probe.Finally,under the guidance of precision and miniaturization principle,a complete set of far-field eddy current testing system is designed to detect pipeline defects based on the simulation results.The detection system designed in this paper consists of the probe,excitation source circuit and signal conditioning circuit.Using STM32F407V8T6 chip as the central controller of the whole system,direct digital frequency synthesizer is used to generate signal source.A/D sampling uses on-chip resources to reduce the size and save space.The detection system supports real-time data storage of SD card.Finally,the far-field eddy current electromagnetic detection system is applicated in the experiments to calibrate the specimen defects.