Research On Cathodic Protection Current Detection System Of Long-Distance Pipeline Based On Magnetic Collecting-Ring Method

Pipeline corrosion and leakage cause a lot of waste of oil and gas resources and serious environmental pollution,and even lead to safety accidents such as fire and explosion.Therefore,anticorrosion is an important content in the field of pipeline engineering.At present,the anticorrosion protection of long-distance pipelines mainly adopts the combination of anticorrosion coating and forced current cathodic protection.The correct selection and control of cathodic protection current determines the protection effect.However,the current detection methods of cathodic protection current have the problems of low precision,poor operation convenience and inability to monitor for a long time.Therefore,it is of great engineering significance to realize long-term and accurate detection of cathodic protection current for long-distance pipelines.As a new type of cathodic protection current detection method,the magnetic collecting-ring method has the advantages of high precision,convenient operation and strong adaptability.However,the related domestic researches on the cathodic protection current detection technology based on the magnetic collecting-ring are relatively late,and the research results are few.Therefore,a set of cathodic protection current detection system for long-distance pipelines based on the magnetic collecting-ring method was developed in this thesis,and the corrosion rate prediction method of LSTM neural network long-distance pipeline based on cathodic protection current density was carried out,which had achieved good results in the experimental test.The main contents of the thesis are as follows:First of all,the working principle of the magnetic collecting-ring method based on the Hall Effect was analyzed,and the mathematical models of the magnetic field of the magnetic collecting-ring and the air gap were established.And the magnetic collecting-ring was modeled and simulated by COMSOL software,and the influence of the material properties,overall structure and air gap opening shape of the magnetic collecting-ring on the magnetic collecting effect was studied,and the optimal design of the magnetic collecting-ring was completed.Then,the cathodic protection current detection system of long-distance pipeline based on the magnetic collecting-ring method was designed.In terms of hardware,the selection of Hall sensor,single-chip microcomputer and wireless communication module and the design of hardware circuit were carried out.In terms of software,Keil u Vision5and Lab VIEW programming environment were used to complete the design of the microcontroller main control program,wireless communication module program and host computer software program.An experimental platform was built.Through the calibration and repeatability experiments of 0.1A-2A DC current,it was verified that the detection accuracy of the system could reach±50m A,the repeatability was good.And the software interface of the host computer had good human-computer interaction,which realized functional requirements for data collection,transmission,display and storage of cathodic protection current.Finally,the influence of cathodic protection current density and other factors on the corrosion rate of long-distance pipelines was analyzed,and the prediction model of long-distance pipeline corrosion rate based on LSTM neural network is established.The prediction results of the model show that the test error is within 7%and the training loss is within 10^-5,which achieved a reasonable prediction of the corrosion rate of long-distance pipelines.