Method and device for detecting accumulated thickness pulse eddy current of fallen oxide skin in austenite boiler tube

Abstract

The invention relates to a method and a device for detecting the accumulated thickness pulse eddy current of the fallen oxide skin in an austenite boiler tube. The method mainly solves the problems that in the prior art, when the traditional means is used to detect the accumulated thickness of the oxide skin in an austenite boiler tube, precise and quantitative detection cannot be possible and that the penetration into the large tube wall is poor under the condition that magnetic conversion occurs at the back tube wall after the high-temperature service of the tube. The method comprises the following steps: buckling a solenoid type pulse eddy current detection sensor on the outside of the tube, wherein a vortex field is generated by the inner oxide skin of the tube under the excitation of the pulse magnetic field and the inductance value of the sensor is increased with the eddy current intensity and the inductance increment related to the accumulated thickness of the oxide skin; enabling the amplitude of the voltage signal outputted by the sensor to indirectly reflect the accumulated thickness of the oxide skin; and further, performing an accumulation simulation detection experiment; processing detection signals in a differential mode; and acquiring a calibration curve of the signal peak value relative to the oxide skin accumulation thickness of the signal peaks; and in the field detection, searching the calibration curve according to the peak value of the detection signal so that the accumulated thickness of the oxide skin in the boiler tube to be measured can be obtained.

Description

technical field [0001] The invention belongs to the technical field of non-destructive testing, and relates to a pulsed eddy current testing method and device for the thickness of exfoliated scale accumulation in an austenitic boiler tube. Background technique [0002] Non-destructive testing (NDT-Nondestructive Testing) is a technology that detects whether there are defects inside or on the surface of the object to be inspected, whether the size has changed, whether there is a hidden danger of clogging, and other physical characteristics without damaging the performance of the object to be inspected. It has been widely used in aerospace, construction, petrochemical and other fields. [0003] In recent years, in order to improve power generation efficiency and develop a low-carbon economy, my country's newly commissioned power plant units have gradually developed in the direction of large capacity and high parameters. Supercritical and ultra-supercritical units have become t...

AI Technical Summary

Problems solved by technology

The advantage is that it can reflect the specific distribution of scale accumulation on the basis of quantitative detection, but its detection method also has certain limitations: conventional single-frequency or multi-frequency eddy currents are difficult to penetrate thicker tubes due to the skin effect. To measure the accumulated oxide scale on the wall, the penetration depth can be increased by using low-frequency eddy current, but the detection signal is susceptible to electromagnetic interference from the surrounding environment; in order to obtain the specific accumulation distribution signal of the oxide scale, it is necessary to conduct a circumferential survey of the sensor along the pipeline during detection. Rotation, the operation is more cumbersome; and there is no solution to the problem of magnetic transformation of austenitic stainless steel after high-temperature service, which affects quantitative detection

However, this method still has no solution to the problem that the magnetic properties of the tube wall change after high temperature service, which affects quantitative detection.

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