High-pressure corrosion investigation AVV2 bio-boiler

Measured corrosion rates of superheater tubes from Avedøre 2 biomass boiler reveal that the corrosion rate increases with steam temperature and accelerates above 540 deg. celsius. Corrosion rates up to 1 mm per 10,000 hours were found for superheater 2 and 3. Flue gas temperature and heat flux had significant effect on corrosion rates through metal surface temperature. Thus, faster corrosion was observed at the outlet of superheater 2 than at the outlet of superheater 3 where the steam temperature is highest. Tube fracture, caused by corrosion, was observed in a test superheater loop after only a few months of operation at a steam temperature of about 580 deg. Celsius. (Energy 11)