磁力扰动法测量铁磁性锅炉管氧化皮堵塞

Magnetic Disturbance Method to Measure Oxide Scales Blockage in Ferromagnetic Boiler Tubes

为解决铁磁性锅炉管氧化皮堵塞检测难题,提出一种磁力扰动法的无损检测方法。首先,采用数值模拟方法对正交放置的两电磁铁作用下的铁磁性锅炉管进行磁场分布特征分析,并通过实验验证仿真结果的正确性;其次,使用声发射技术对磁场作用下氧化皮碰撞管壁发出的声音进行采集,建立波形特征参数与氧化皮堵塞面积比的定量关系。结果表明:铁磁性锅炉管磁导率的非线性特点使得两电磁铁在管道内形成一种能穿透管壁直接吸引氧化皮的独特磁场,其吸引能力下限低至10%堵塞面积比;以幅值绝对值为权重的声信号加权平均时间可以作为判定被检管道堵塞面积比是否超标的依据。该方法具有一定的工程应用前景。

In order to solve the difficult problem of detecting the oxide scales blockage in ferromagnetic boiler tubes,a non-destructive testing method called magnetic disturbance method was proposed.Numerical simula-tion is used to analyze the magnetic field distribution characteristics of the ferromagnetic boiler tube under the ac-tion of two electromagnets placed orthogonally,and experiments have been done to verify the correctness of the simulation results.The acoustic emission technology is applied to collect the sound generated by the hitting of oxide scale towards the tube wall under the magnetic field,thereby establishing the quantitative relationship be-tween the waveform characteristic parameters and the radio of oxide scales blockage area.Test results indicate that the two electromagnets form a unique magnetic field in the pipe that can penetrate the pipe wall and directly attract the oxide scales because of the non-linear characteristics of the magnetic permeability of the ferromagnetic boiler pipe.The attraction limit of this method is as low as 10%oxide scales blockage area.Moreover,the weighted average time of acoustic signals weighted by the absolute value of amplitude can be used to judge whether the ratio of oxide scales blockage area of the inspected pipe exceeds the standard,which indicates the proposed method has engineering application prospects.