Abstract
Protective coatings offer one route to increase the lives of heat exchangers in pulverised fuel power plants. A range of candidate coatings have been exposed on the waterwall and superheaters of a 500 MWe UK power station unit for periods of up to ~4 years (24,880 operating hours), during which time this unit was fired on a mixture of UK and world-traded coals. Both nickel- and iron-based candidate coatings were included, applied using high velocity oxy-fuel or arc-wire process; a selection of these also had a surface sealant applied to investigate its effectiveness. Dimensional metrology was used to evaluate coating performances, with SEM/EDX examinations used to investigate the various degradation mechanisms found. Both the waterwall and superheater environments generated their characteristic corrosion damage morphologies which depended on the radial positions around the tube. Coating performances were found to depend on the initial coating quality rather than composition, and were not improved by the use of a sealant.
Highlights
Pulverised coal-fired power stations currently produce much of the electricity used in the world, but they generate CO2 emissions and often have efficiencies of only *35 to 40% [1]
This paper reports the results of the long-term exposure of a selection of candidate protective coatings on the waterwalls and superheater tubes within a 500 MWe pulverised fuel-fired unit of a UK power station
Coatings Exposed on Waterwall Tubes The cross-sections through the exposed samples showed that all of the coatings had experienced fireside corrosion on their surfaces at the crown (i.e. 12 o’clock positions), but only the highvelocity oxy-fuel (HVOF) alloy 625 coatings had disappeared completely
Summary
Pulverised coal-fired power stations currently produce much of the electricity used in the world, but they generate CO2 emissions and often have efficiencies of only *35 to 40% [1]. This paper reports the results of the long-term exposure of a selection of candidate protective coatings on the waterwalls and superheater tubes within a 500 MWe pulverised fuel-fired unit of a UK power station. These coatings were manufactured and installed during a plant outage in 2011, as part of the UK ASPIRE R&D project. The coatings were exposed for 24,880 operating hours before being removed and examined during the unit’s major outage in 2015, as part of the EU NEXTGENPOWER R&D project During this exposure, the power plant was fired using a mixture of UK and world-traded coals. There were significant differences between the performances of coatings in the waterwall and superheater environments
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
