Abstract

Austenitic boiler tubes are key components in modern coal-fired power plants but often suffer from blockage or even rupture caused by the accumulation of steam-side oxide scales. Existing nondestructive testing methods are somewhat deficient to quantify the accumulated height of exfoliated oxide scales. Pulsed eddy current (PEC) technique has unique merits such as deep penetration depth and diverse signal features, offering a great possibility to address this issue. This work serves as an exploratory study for applying PEC technique to measure the scales accumulation. Finite element modeling and experimental work are conducted to validate the feasibility and effectiveness of PEC measurement under different circumstances. The PEC signal peak shows a linear relationship with the accumulated height and thereby is used as the signal feature for the quantitative measurement of accumulated height. A flexible sensor consisting of a replaceable flat cable with connectors at the ends is designed, following by the analyses of sensor offset and liftoff effects. To distinguish the unevenness of accumulation, the sensor-coil array scheme is proposed and the output array signals successfully characterize the profile of inner accumulation. Finally, a referencing strategy is explained to eliminate the interference due to magnetism transformation of the tube wall.

中文翻译：

---

使用脉冲涡流测试法测量奥氏体锅炉管中氧化铁鳞片的累积高度

摘要

奥氏体锅炉管是现代燃煤电厂的关键部件，但经常因蒸汽侧氧化物垢的积聚而导致堵塞甚至破裂。现有的非破坏性测试方法在某种程度上不足以量化剥落的氧化皮的累积高度。脉冲涡流（PEC）技术具有独特的优点，例如深穿透深度和多样化的信号特征，为解决此问题提供了极大的可能性。这项工作是应用PEC技术测量水垢积累的探索性研究。进行了有限元建模和实验工作，以验证在不同情况下进行PEC测量的可行性和有效性。PEC信号峰值与累积高度呈线性关系，因此被用作定量测量累积高度的信号特征。设计了一种柔性传感器，该传感器由可更换的扁平电缆组成，该扁平电缆的两端带有连接器，然后分析了传感器的偏移量和升力效应。为了区分堆积的不均匀性，提出了传感器线圈阵列方案，并且输出阵列信号成功地表征了内部堆积的轮廓。最后，解释了一种参考策略，以消除由于管壁的磁性转换而产生的干扰。为了区分堆积的不均匀性，提出了传感器线圈阵列方案，并且输出阵列信号成功地表征了内部堆积的轮廓。最后，解释了一种参考策略，以消除由于管壁的磁性转换而产生的干扰。为了区分堆积的不均匀性，提出了传感器线圈阵列方案，并且输出阵列信号成功地表征了内部堆积的轮廓。最后，解释了一种参考策略，以消除由于管壁的磁性转换而产生的干扰。