Development of On-Line Monitoring Systems for High Temperature Components in Power Plants

Abstract

To accurately detect deformation and extend the component life beyond the original design limits, structural safety monitoring techniques have attracted considerable attention in the power and process industries for decades. In this paper an on-line monitoring system for high temperature pipes in a power plant is developed. The extension-based sensing devices are amounted on straight pipes, T-Joints and elbows of a main steam pipeline. During on-site monitoring for more than two years, most of the sensors worked reliably and steadily. However, the direct strain gauge could not work for long periods because of the high temperature environment. Moreover, it is found that the installation and connection of the extensometers can have a significant influence on the measurement results. The on-line monitoring system has a good alarming function which is demonstrated by detecting a steam leakage of the header.

An Improved Metal-Packaged Strain Sensor Based on A Regenerated Fiber Bragg Grating in Hydrogen-Loaded Boron–Germanium Co-Doped Photosensitive Fiber for High-Temperature Applications

“…However, traditional strain gauges are not reliable for prolonged measurements at high temperatures [2], in addition to nonlinearity of thermal-induced apparent strains and susceptibility to electromagnetic interference (EMI). Measurement accuracy with optical strain gauges and digital image correlation (DIC) is also adversely affected by insufficient image quality due to the inevitable degradation of markers exposed to high temperatures with time [3].…”

Measurement of small rotation angle of flange joints by a novel flexure magnifying mechanism

“…However, the leakage behavior is easy to occur near the minimum rotation angle region owing to the significant decrease of gasket stress. Therefore, the minimum and the maximum rotation angles and their locations of flange The included angle β can be expressed as (22) The rotation angle under external bending moment can be expressed as: (23) It should be noted that α1=α4, and α2=α3=0 under the pretightening and internal pressure condition.…”

“…Therefore, the rigidity and amplification, which are regarded as the key parameters of flexure-hinge mechanisms, are widely investigated by many researchers in recent years [19,20,21,22] . Recently, Tu and Xuan et al [23,24,25,26] developed various extensometers to monitor the creep strain of pipeline at elevated temperature, especially by magnifying mechanisms. However, according to the best knowledge of authors, very few references introduced the deformation monitoring of bolted flange joints during the assemble or operation process, especially the rotation angle of flange.…”

Optimal Design Methodology of Tapered Waveguide Transducers for Thickness Monitoring

“…There are many pressure vessels and pipes working in harsh environments, e.g., high temperature or corrosive. Online monitoring of the wall thinning caused by erosion or corrosion is very important for the safe operation of such equipment utilizing permanently installed transducers [1][2][3]. However, transducers will suffer from depolarization when they are exposed to high temperature or corrosion for a long time which considerably limits the application for conventional sensory devices in structural health monitoring (SHM) and non-destructive evaluation [4,5].…”