Potential high temperature corrosion problems due to co-firing of biomass and fossil fuels

Melanie Montgomery, T. Vilhelmsen, S.A. Jensen

    Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearch

    Abstract

    Over the past years, considerable high temperature corrosion problems have been encountered when firing biomass in power plants due to the high content of potassium chloride in the deposits. Therefore to combat chloride corrosion problems co-firing of biomass with a fossil fuel has been undertaken. This results in potassium chloride being converted to potassium sulphate in the combustion chamber and it is sulphate rich deposits that are deposited on the vulnerable metallic surfaces such as high temperature superheaters. Although this removes the problem of chloride corrosion, other corrosion mechanisms appear such as sulphidation and hot corrosion due to sulphate deposits. At Studstrup power plant Unit 4, based on trials with exposure times of 3000 hours using 0-20% straw co-firing with coal, the plant now runs with a fuel of 10% straw + coal. After three years exposure in this environment, the internal sulphidation is much more significant than that revealed in the demonstration project. Avedøre 2 main boiler is fuelled with wood pellets + heavy fuel oil + gas. Some reaction products due to the presence of vanadium compounds in the heavy oil were detected, i.e. iron vanadates. However, the most significant corrosion attack was due to sulphidation attack at the grain boundaries of 18-8 steel after 3 years exposure. The corrosion mechanisms and corrosion rates are compared with biomass firing and coal firing. Potential corrosion problems due to co-firing biomass and fossil fuels are discussed.
    Original languageEnglish
    Title of host publicationEurocorr 2007 : Freiburg
    VolumeGermany 9-13 September 2007
    Publication date2007
    Publication statusPublished - 2007
    EventEUROCORR 2007: Progress by Corrosion Control - Breisgau, Germany
    Duration: 9 Sep 200713 Sep 2007

    Conference

    ConferenceEUROCORR 2007
    CountryGermany
    CityBreisgau
    Period09/09/200713/09/2007

    Keywords

    • co-firing
    • High temperature corrosion
    • biomass
    • sulphidation

    Cite this

    Montgomery, M., Vilhelmsen, T., & Jensen, S. A. (2007). Potential high temperature corrosion problems due to co-firing of biomass and fossil fuels. In Eurocorr 2007: Freiburg (Vol. Germany 9-13 September 2007)