Fluidized bed agglomeration during biomass combustion (Contributo in atti di convegno)

Type
Label
  • Fluidized bed agglomeration during biomass combustion (Contributo in atti di convegno) (literal)
Anno
  • 2000-01-01T00:00:00+01:00 (literal)
Alternative label
  • F. Scala, R. Chirone, P. Salatino (2000)
    Fluidized bed agglomeration during biomass combustion
    in Proc. of 7th Int. Conf. Multiphase Flow in Industrial Plants, Bologna, Italy
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • F. Scala, R. Chirone, P. Salatino (literal)
Pagina inizio
  • 155 (literal)
Pagina fine
  • 164 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • Dipartimento di Ingegneria Chimica - Università degli Studi di Napoli \"Federico II\" Istituto di Ricerche sulla Combustione - C.N.R. (literal)
Titolo
  • Fluidized bed agglomeration during biomass combustion (literal)
Abstract
  • Fluidized bed biomass combustion experiments have been carried out in a bed of pure quartz at temperatures ranging from 700°C to 850°C at different oxygen concentrations in order to investigate the agglomeration tendency of the bed. SEM/EDX analysis of the silica bed particles after the tests was performed to determine the formation of alkali rich layers on inert bed particles and possibly of silicate melts. Results indicated that large quantities of biomass ashes are retained on the bed particles under all operating conditions. Only at the higher temperatures, however, molten surface layers and agglomerated bed particles could be noticed. Experimental results have been interpreted on the basis of a single char particle combustion model applied to both fines and coarse biomass particles burn out in a fluidized bed. Calculations show that extremely high temperatures are rapidly reached by fine particles even at very low oxygen concentrations. These temperatures are well beyond typical alkali-silicate compounds melting temperatures. On the other hand coarse particles burn at temperatures only slightly above bed temperature. Experimental and theoretical results indicate that the following mechanism is relevant to the fate of ashes during fluidized bed combustion of biomass: ash is mostly detached from the coarse char as attrited fines whose temperature is raised significantly by carbon afterburning. Fines can further adhere onto inert bed particles, with formation of alkali-rich surface layers. If the bed temperature is higher than the alkali-silicate eutectic, a melt forms that enhances bed particle stickiness and may ultimately lead to bed agglomeration. (literal)
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