Effect of temperature gradient on composition and morphology of synthetic chlorine-containing biomass boiler deposits

Daniel Lindberg, Jonne Niemi, Markus Engblom, Patrik Yrjas, Tor Laurén, Mikko Hupa

Tutkimustuotos: LehtiartikkeliArtikkeliTieteellinenvertaisarvioitu

46 Sitaatiot (Scopus)

Abstrakti

A novel laboratory method has been developed to study the chemical and physical behavior of ash deposits in a temperature gradient. Experiments with synthetic alkali salt mixtures similar to biomass boiler deposits show that alkali chlorides evaporate from hotter particles in the deposit and condense on colder particles closer to the cooled metal surface or even condense on the metal surface. Formation of a partially or completely molten layer in the outer hotter region closer to the flue gas is also observed in the experiments.The effect of time is shown to be significant for the enrichment of chlorides as longer experiment time leads to higher amounts of vaporization, transport and condensation within the deposits.These effects are quantitatively verified using Computational Fluid Dynamics modeling.The transport of alkali chloride vapors becomes negligible if the deposit and metal temperature is cold enough. An enrichment of alkali chlorides towards the cooled metal surface occurs and can increase chlorine-induced corrosion of superheaters as the deposits mature over time.The experimental observations are similar to superheater deposit morphologies observed in biomass boilers, such as straw-fired grate boilers.
AlkuperäiskieliEi tiedossa
Sivut285–298
JulkaisuFuel Processing Technology
Vuosikerta141, Part 2
DOI - pysyväislinkit
TilaJulkaistu - 2016
OKM-julkaisutyyppiA1 Julkaistu artikkeli, soviteltu

Keywords

  • Superheater corrosion
  • molten salt
  • Alkali chloride induced corrosion
  • computational fluid dynamics

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