Economizer water-wall damages initiated by feedwater impurities

The main causes of efficiency loss in thermal power plants are boiler tube failures that diminish unit reliability and availability, and raise the cost of the electric energy. For that reason, regular examination of boiler tubes is indispensable measure for prevention future malfunctions of power un...

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Bibliographic Details
Published in:Hemijska industrija 2014, Vol.68 (5), p.559-563
Main Authors: Vidojkovic, Sonja, Onjia, Antonije, Devecerski, Aleksandar, Grahovac, Nebojsa, Nastasovic, Aleksandra
Format: Article
Language:English
Subjects:
boiler tube
Boiler tubes
corrosion
deposition
Electric power plants
Energy measurement
Feedwater
feedwater impurities
Hematite
Impurities
Magnetite
Malfunctions
Pitting (corrosion)
Power efficiency
Steam electric power generation
Stress corrosion cracking
Water damage
X-ray diffraction
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Summary:The main causes of efficiency loss in thermal power plants are boiler tube failures that diminish unit reliability and availability, and raise the cost of the electric energy. For that reason, regular examination of boiler tubes is indispensable measure for prevention future malfunctions of power units. Microscopic examination of economizer inner wall microstructure, analysis of chemical composition of deposit using x-ray diffraction (XRD) and scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) has been performed in a subcritical power plant. Stress corrosion cracking, pitting corrosion, destroyed protective magnetite layer, presence of magnetite and hematite in deposit and corrosive impurities within the cracks were indicated the effect of inadequate quality of feedwater that can not entirely ensure reliable operation of the boiler. It may be stated that maintenance of present boiler does not provide its reliable operation. Extensive chemical control of water/steam cycle was recommended.
ISSN:0367-598X
2217-7426
DOI:10.2298/HEMIND130715082V