Fireside corrosion in German fossil‐fuel fired power plants. Appearence, mechanism and causes

摘要

AbstractFireside corrosion in German fossil fuel‐fired boilers is described out of the view of a laboratory engaged with failure analysis.With German boiler design and German fossil fuel ferritic steels can be used for the tubing in the evaporator and superheater section. Corrosion rates, which have to be expected normally are below 10 nm/h for evaporator tubes and below 25 nm/h for superheater tubes. The appearance of corroded tubes is described and discussed in respect of the corrosion mechanism.In the evaporator section enhanced corrosion risk is mainly due to an increased chemical load, namely reducing conditions or chlorine compounds in the combustion products.In the superheater section higher than normal metal temperatures and stresses, by which the integrity of the oxide layer is destroyed, are the most important factors for increased corrosion rate