How to control superheater tube corrosion in FB boilers which use wood and wood waste as fuel

Markku Orjala, Riikka Ingalsuo, Kari Paakkinen, Martti Mäkipää, Maria Oksa, T. Malkow, R. Fordham, D. Baxter

    Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

    Abstract

    The objective of this study is to determine the safe combustion conditions and optimised material technologies in circulating (CFB) as well as bubbling fluidised-bed (BFB) boilers using wood chips as fuel. The combustion and co-firing properties of fuels produced by different forest chains were studied first in VTT's test facilities and later in industrial-scale power plant boilers. The formation of alkaline and chlorine compounds and their effect on boiler fouling and corrosion were also studied also by cooled deposit and material probes. In addition to analysis of material exposures in boilers, materials embedded in different mixtures of wood and peat ashes with or without chloride were tested in the laboratory. Deposits and changes in their chemical phase composition compounds and the corrosion of materials were analysed by SEM-EDX and optical microscopy. Solutions to control superheater tube corrosion optimally were considered with reference to the experimental results and to model calculations performed using the F.A.C.T program. Utilisation of logging residue chips can cause deposition of potassium and sodium chloride on the heat exchanger surfaces and enhanced corrosion due to the chlorine. The harmful formation of alkaline and chlorine compounds on boiler surfaces could be prevented by co-firing sulphur-containing fuel. However, to suppress corrosion that is not directly related to alkali chloride deposition on superheater tube surfaces, optimised material solutions have to be seeked.
    Original languageEnglish
    Title of host publication10th International Symposium on Corrosion in the Pulp and Paper Industry, ISCPPI. Vol. 1
    Place of PublicationEspoo
    PublisherVTT Technical Research Centre of Finland
    Pages117-136
    ISBN (Electronic)951-38-5724-7
    ISBN (Print)951-38-5720-4
    Publication statusPublished - 2001
    MoE publication typeA4 Article in a conference publication
    Event10th International Symposium On corrosion in the Pulp and Paper Industry, ISCPPI - Helsinki, Finland
    Duration: 21 Aug 200124 Aug 2001

    Publication series

    SeriesVTT Symposium
    Number214
    ISSN0357-9387

    Conference

    Conference10th International Symposium On corrosion in the Pulp and Paper Industry, ISCPPI
    Abbreviated title10th ISCPPI
    CountryFinland
    CityHelsinki
    Period21/08/0124/08/01

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