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Bed material deposition in cyclones of wood fuel fired circulating fluidized beds (CFBs);

Tranvik, AC; Öhman, M and Sanati, Mehri LU (2007) In Energy and Fuels 21(1). p.104-109
Abstract
Bed material samples were collected at different times from a full-scale combustion boiler, and bed material deposits were taken from the cyclone and the riser at two different occasions from a wood-fired circulating fluidized bed boiler (104 MWth). The bed materials and the bed material deposits were analyzed with environmental scanning electron microscopy/energy-dispersive X-ray spectroscopy (ESEM/EDXS) to determine the characteristics of the formed bed particle layers and bed material deposits. On the basis of their elemental composition, the corresponding melting behavior was estimated, using data extracted from phase diagrams. The bed material was also fractionated by sieving, and the alkali metal concentration dependence on the... (More)
Bed material samples were collected at different times from a full-scale combustion boiler, and bed material deposits were taken from the cyclone and the riser at two different occasions from a wood-fired circulating fluidized bed boiler (104 MWth). The bed materials and the bed material deposits were analyzed with environmental scanning electron microscopy/energy-dispersive X-ray spectroscopy (ESEM/EDXS) to determine the characteristics of the formed bed particle layers and bed material deposits. On the basis of their elemental composition, the corresponding melting behavior was estimated, using data extracted from phase diagrams. The bed material was also fractionated by sieving, and the alkali metal concentration dependence on the particle size was determined. The bed material deposits found in the cyclone and the riser consisted of bed particles embedded in a low-temperature melting (sticky) alkali metal silicate (K and Na) that resemble the composition of the layer found around the cracks in older quartz bed particles. The alkali silicate formation, which is in progress in the vicinity of the formed cracks of older quartz bed particles, significantly transforms a large part of the bed particle and makes it less resistant against fragmentation. The results therefore suggest that elutriated alkali silicate-rich fragments from old quartz bed particles are responsible for bed material depositions in cyclones of wood-fired circulating fluidized beds (CFBs). (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Energy and Fuels
volume
21
issue
1
pages
104 - 109
publisher
The American Chemical Society
external identifiers
  • Scopus:33846974676
ISSN
0887-0624
DOI
10.1021/ef060175f
language
English
LU publication?
yes
id
ef42d594-2034-42ba-b91d-3c31e6749ec4 (old id 638412)
date added to LUP
2009-02-26 11:41:43
date last changed
2016-11-17 11:35:56
@misc{ef42d594-2034-42ba-b91d-3c31e6749ec4,
  abstract     = {Bed material samples were collected at different times from a full-scale combustion boiler, and bed material deposits were taken from the cyclone and the riser at two different occasions from a wood-fired circulating fluidized bed boiler (104 MWth). The bed materials and the bed material deposits were analyzed with environmental scanning electron microscopy/energy-dispersive X-ray spectroscopy (ESEM/EDXS) to determine the characteristics of the formed bed particle layers and bed material deposits. On the basis of their elemental composition, the corresponding melting behavior was estimated, using data extracted from phase diagrams. The bed material was also fractionated by sieving, and the alkali metal concentration dependence on the particle size was determined. The bed material deposits found in the cyclone and the riser consisted of bed particles embedded in a low-temperature melting (sticky) alkali metal silicate (K and Na) that resemble the composition of the layer found around the cracks in older quartz bed particles. The alkali silicate formation, which is in progress in the vicinity of the formed cracks of older quartz bed particles, significantly transforms a large part of the bed particle and makes it less resistant against fragmentation. The results therefore suggest that elutriated alkali silicate-rich fragments from old quartz bed particles are responsible for bed material depositions in cyclones of wood-fired circulating fluidized beds (CFBs).},
  author       = {Tranvik, AC and Öhman, M and Sanati, Mehri},
  issn         = {0887-0624},
  language     = {eng},
  number       = {1},
  pages        = {104--109},
  publisher    = {ARRAY(0xa5624a8)},
  series       = {Energy and Fuels},
  title        = {Bed material deposition in cyclones of wood fuel fired circulating fluidized beds (CFBs);},
  url          = {http://dx.doi.org/10.1021/ef060175f},
  volume       = {21},
  year         = {2007},
}