Abstract
The use of low-emission combustion technologies in power boilers has contributed to a significant increase in the rate of high-temperature corrosion in boilers and increased risk of failure. The use of low quality biomass and waste, caused by the current policies pressing on the decarbonization of the energy generation sector, might exacerbate this problem. Additionally, all of the effects of the valorization techniques on the inorganic fraction of the solid fuel have become an additional uncertainty. As a result, fast and reliable corrosion diagnostic techniques are slowly becoming a necessity to maintain the security of the energy supply for the power grid. Non-destructive testing methods (NDT) are helpful in detecting these threats. The most important NDT methods, which can be used to assess the degree of corrosion of boiler tubes, detection of the tubes’ surface roughness and the internal structural defects, have been presented in the paper. The idea of the use of optical techniques in the initial diagnosis of boiler evaporators’ surface conditions has also been presented.
Highlights
The use of low-emission combustion techniques in pulverized coal-fired boilers has contributed, to a large extent, to intensifying the high-temperature corrosion processes, causing the relatively quick wastage of wall tubes [1,2]
Diagnostics are performed using visual inspection, followed by sampling sections of piping for laboratory testing. This is time-consuming as removed sections need to be replaced before the startup of the boiler after the inspection
One of the interesting techniques is in situ metallographic testing, which can be performed during periodic boiler inspections [74]
Summary
The use of low-emission combustion techniques in pulverized coal-fired boilers has contributed, to a large extent, to intensifying the high-temperature corrosion processes, causing the relatively quick wastage of wall tubes [1,2]. The erosion-corrosion boiler tube-thick losses increase the exploitation expenses by increasing the frequency of the necessary full and partial screen replacements. They strongly negatively affect the reliability and availability of the whole power unit. Diagnostics are performed using visual inspection, followed by sampling sections of piping for laboratory testing This is time-consuming as removed sections need to be replaced before the startup of the boiler after the inspection. Any left-over tensile stress can lead to the formation of cracks, as observed by Duarte et al [11]
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