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Physical and Chemical Characterization of Aerosol Particles Formed During the Thermochemical Conversion of Wood Pellets Using a Bubbling Fluidized Bed Gasifier

Gustafsson, Eva; Strand, Michael and Sanati, Mehri LU (2007) In Energy & Fuels 21(6). p.3660-3667
Abstract
Product gas obtained through biomass gasification can be upgraded to hydrogen-rich synthesis gas. The synthesis gas can be further converted to liquid or gaseous fuels. However, the raw product gas contains both gas- and particle-phase impurities that can negatively affect both catalysts and hot-gas filters used for upgrading and cleaning. The present study aimed to characterize, both physically and chemically, aerosol particles formed during the steam- and oxygen-blown biomass gasification of wood pellets in an atmospheric 20 kW bubbling fluidized bed (BFB) gasifier. The product gas from the gasifier was sampled upstream from the cyclone at 500 °C. The particle number size distribution determined using a scanning mobility particle sizer... (More)
Product gas obtained through biomass gasification can be upgraded to hydrogen-rich synthesis gas. The synthesis gas can be further converted to liquid or gaseous fuels. However, the raw product gas contains both gas- and particle-phase impurities that can negatively affect both catalysts and hot-gas filters used for upgrading and cleaning. The present study aimed to characterize, both physically and chemically, aerosol particles formed during the steam- and oxygen-blown biomass gasification of wood pellets in an atmospheric 20 kW bubbling fluidized bed (BFB) gasifier. The product gas from the gasifier was sampled upstream from the cyclone at 500 °C. The particle number size distribution determined using a scanning mobility particle sizer (SMPS) was bimodal, with modes at 20–30 and 400 nm, mobility equivalent diameters (dB). The total mean number concentration of particles with dB = 15–670 nm was approximately 7 × 105 particles/cm3; however, the concentration of particles with dB < 80 nm fluctuated. The particle mass size distribution determined using a low-pressure impactor (LPI) was bimodal, and the total mass concentration of particles with aerodynamic diameters (dae) < 5 µm was 310 mg/m3. Microscopy analysis of particulate matter on the lower LPI stages, expected to sample particles with dae < 0.4 µm, revealed structures approximately 10 µm in diameter. In addition, the mass concentration of particles with dae < 0.5 µm determined using a LPI was higher than that estimated using a SMPS, possibly because of the bounce-off or re-entrainment of coarser particles from higher LPI stages. Elementary analysis of the particulate matter indicated that it was dominated by carbon. The collected particulate matter was stable when heated in nitrogen to 500 °C, indicating that the carbon was not present as volatile tars but more likely as char or soot. The particulate matter collected on all LPI stages contained a small percentage of ash (noncarbonaceous inorganic material), with calcium as the dominant element. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Energy & Fuels
volume
21
issue
6
pages
3660 - 3667
publisher
The American Chemical Society
external identifiers
  • scopus:37249026833
ISSN
0887-0624
DOI
10.1021/ef7002552
language
English
LU publication?
yes
id
d0c2abb5-2752-4f81-85be-e341682ef32d (old id 1951867)
date added to LUP
2011-05-12 15:12:29
date last changed
2017-04-16 04:30:17
@article{d0c2abb5-2752-4f81-85be-e341682ef32d,
  abstract     = {Product gas obtained through biomass gasification can be upgraded to hydrogen-rich synthesis gas. The synthesis gas can be further converted to liquid or gaseous fuels. However, the raw product gas contains both gas- and particle-phase impurities that can negatively affect both catalysts and hot-gas filters used for upgrading and cleaning. The present study aimed to characterize, both physically and chemically, aerosol particles formed during the steam- and oxygen-blown biomass gasification of wood pellets in an atmospheric 20 kW bubbling fluidized bed (BFB) gasifier. The product gas from the gasifier was sampled upstream from the cyclone at 500 °C. The particle number size distribution determined using a scanning mobility particle sizer (SMPS) was bimodal, with modes at 20–30 and 400 nm, mobility equivalent diameters (dB). The total mean number concentration of particles with dB = 15–670 nm was approximately 7 × 105 particles/cm3; however, the concentration of particles with dB &lt; 80 nm fluctuated. The particle mass size distribution determined using a low-pressure impactor (LPI) was bimodal, and the total mass concentration of particles with aerodynamic diameters (dae) &lt; 5 µm was 310 mg/m3. Microscopy analysis of particulate matter on the lower LPI stages, expected to sample particles with dae &lt; 0.4 µm, revealed structures approximately 10 µm in diameter. In addition, the mass concentration of particles with dae &lt; 0.5 µm determined using a LPI was higher than that estimated using a SMPS, possibly because of the bounce-off or re-entrainment of coarser particles from higher LPI stages. Elementary analysis of the particulate matter indicated that it was dominated by carbon. The collected particulate matter was stable when heated in nitrogen to 500 °C, indicating that the carbon was not present as volatile tars but more likely as char or soot. The particulate matter collected on all LPI stages contained a small percentage of ash (noncarbonaceous inorganic material), with calcium as the dominant element.},
  author       = {Gustafsson, Eva and Strand, Michael and Sanati, Mehri},
  issn         = {0887-0624},
  language     = {eng},
  number       = {6},
  pages        = {3660--3667},
  publisher    = {The American Chemical Society},
  series       = {Energy & Fuels},
  title        = {Physical and Chemical Characterization of Aerosol Particles Formed During the Thermochemical Conversion of Wood Pellets Using a Bubbling Fluidized Bed Gasifier},
  url          = {http://dx.doi.org/10.1021/ef7002552},
  volume       = {21},
  year         = {2007},
}