Fouling tendency of ash resulting from burning mixtures of biofuels. Part 2: Deposit chemistry

M Theis, BJ Skrifvars, Maria Zevenhoven, Mikko Hupa, HH Tran

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    Abstract

    Mixtures of peat with bark and peat with straw were burned in a lab-scale entrained flow reactor under controlled conditions, and deposits were collected on an air-cooled probe at a temperature of 550 degrees C. The fuel and deposit compositions were compared using chemical fractionation analysis and SEM/EDX. Chemical fractionation analysis was capable of explaining the relative fouling tendency of peat, bark, and straw. The composition of deposits obtained from firing peat, bark, and straw individually resembled the composition of their ashes. When firing peat-bark and peat-straw mixtures, it was found that the deposition rate only started to increase when the Cl/S molar ratio in the feed ash exceeded 0.15. The composition of the ensuing deposits resembled the deposits obtained from burning either bark or straw individually. For peat-bark mixtures it was concluded that the presence of S in the feed suppresses deposition by sulfating chloride compounds, leading to deposits that contain less Cl and have less molten phase. For peat-straw mixtures it was concluded that the deposition behaviour is governed by other mechanisms than the interaction of Cl and S.
    Original languageUndefined/Unknown
    Pages (from-to)1992–2001
    Number of pages10
    JournalFuel
    Volume85
    Issue number14-15
    DOIs
    Publication statusPublished - 2006
    MoE publication typeA1 Journal article-refereed

    Keywords

    • chemical fractionation analysis
    • co-firing
    • deposition

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