Quantitative detection method and detection instrument for scale accumulation in pipeline

Abstract

The invention provides a quantitative detection method and a detector for detecting the accumulated oxide scales in the pipelines. The quantitative detection method comprises the following steps: arranging a special sensor on a primary detection point on the surface of a pipeline to be detected, moving the special sensor along the axial direction of the pipeline, wherein the special sensor can generate a stable, constant, and strong magnetic field on each detection points of the pipeline; exciting and magnetizing the oxides on the detection points in the pipeline through the strong magnetic fields, wherein the oxides can generate primary magnetic field signals after being excited and magnetized; receiving the primary magnetic field signals by the special sensor, processing the signals, sending the processed signals to a host computer; continuously analyzing the digital magnetic field signals by the host computer, and finally obtaining the accumulated oxide scale amount in each detection point of the pipeline by combining the primary detection point coordinate and the moving distance of the special sensor in the pipeline. The detection method and detector have the advantages of simple detection principle, portability, high sensitivity, and low cost, can be used to measure the accumulated oxide scale in stainless pipelines in a power plant, and have a good application prospect.

Description

technical field [0001] The invention belongs to the technical field of nondestructive testing, and in particular relates to a quantitative detection method and a detection instrument for oxide scale accumulation in pipelines. Background technique [0002] In recent years, stainless steel with high temperature resistance and better corrosion resistance has been widely used in boilers of large thermal power generating units to manufacture superheater and reheater pipes. However, after the boiler has been in operation for a long time, the long-term harsh working conditions will easily oxidize the inner wall of the pipeline and form oxide scales on the surface of the inner wall. When the working conditions and environment change drastically, such as when the furnace is stopped and started, the oxide scale on the inner wall of the pipeline is very easy to peel off, and the peeled off scale is easy to accumulate on the elbows of the superheater and reheater pipes, and even block t...

AI Technical Summary

Problems solved by technology

However, there are still many defects in this detection method. On the one hand, an AC magnetic field is used to magnetize the pipeline, and eddy currents are generated on the wall of the non-magnetic pipeline due to electromagnetic induction, which in turn attenuates the AC magnetization field and the induced magnetic signal of the oxide in the tube. The detection sensitivity is reduced; on the other hand, the amplitude strength of the AC magnetic field is low, and the penetration depth of the magnetic field is small, which has the problem of weak detection signal when detecting thick-walled pipes, which affects the detection sensitivity

In addition, like eddy current detection, the input and output of the detection device are all AC signals, and the output signal (the signal output from the detection device to the sensor) usually requires relatively large power, while the input signal (the magnetic field signal detected by the sensor) is microampere Level current, it is difficult to accurately detect the magnitude of the current under complex working conditions, so the signal generation system and signal processing system of the detection device are relatively complicated, and the detection signal is relatively easy to be interfered

In addition, the production of sensors is also more complicated. For example, the sensor probe of the eddy current detection device is expensive, and a specific type of probe is required for a pipeline; this meal, the energy consumption of the detection device is also relatively large

Therefore, although this method has made great progress compared with the ray method, it still has problems such as complex system, expensive detection device, and limited detection sensitivity.

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