5通道铁磁探测仪的研发与锅炉管堵塞检测

描述了5通道铁磁探测仪的研发和应用，该仪器能在管外发现发电锅炉过热器管和再热器管内是否有铁锈堆积，并评估堵塞程度，目的是通过检测防止爆管事故。采用磁学探测方法，在管外表面的1条圆周线上布置5个测量点，进行了有限元数值模拟和标定曲线的计算。对计算结果进行了实验验证，与计算值相比较，测量值的标准误差（相对误差）为5.2%。现场检测得到的堵塞面积与管内孔的面积之比，与X射线摄影测得的结果比较，确定铁磁探测仪检测的标准误差（绝对误差）为3.9%。通过为5家热电厂进行过热器管和再热器管堵塞检测，发现超标堵塞30多处，解剖验证无一误报，所以用该仪器进行堵塞检测能够防止上述锅炉管爆管事故。

Development of Five Channels Tester Detecting Ferromagnetic Objects and Blockage Detection on Boiler Tubes

The development and applications of the tester detecting ferromagnetic objects is described. The tester can be used to detect and evaluate quantitatively blockages by rust in superheater tubes and reheater tubes so as to avoid explosion of the tubes. By using the magnetic measurement method,five points where blockage detection will be made are set on tube surface along a circumference. Simulations by finite element method and calculation of calibration curves are conducted. The results of calculation are verified by experiments. Comparing with the calculated values, the standard error of the measured values, which is named as the relative error, is 5.2%. The standard error of the field-measured proportion of blocked area in the tube to the area of the cross section of the tube bore is 3.9%, compared with that measured by X-ray photography, which is named as absolute error. Blockage detections on tubes have been implemented for the five power plants. More than 30 blockages the area percentage of which is more than 30% have been found. Cutting the tubes and removing the blockages out of the tubes indicates that no false report of blockage have happened. It is concluded that blockage detection on the tube using the tester is effective for prevention of the tube from explosion accident.