Ash vaporization in circulating fluidized bed coal combustion
Journal Article
·
· Aerosol Science and Technology
- Univ. of Gent (Belgium)
- Univ. of Kentucky, Lexington, KY (United States)
In this work, the vaporization of the ash-forming constituents in circulating fluidized bed combustion (CFBC) in a full-scale 80 MW{sub th} unit was studied. Ash vaporization in CFBC was studied by measuring the fly ash aerosols in a full-scale boiler upstream of the electrostatic precipitator (ESP) at the flue gas temperature of 125{degree}C. The fly ash number size distributions showed two distinct modes in the submicrometer size range, at particle diameters 0.02 and 0.3 {mu}m. The concentration of the ultrafine 0.02-{mu}m mode showed a large variation with time and it decreased as the measurements advanced. The concentration of the 0.02-{mu}m mode was two orders of magnitude lower than in the submicrometer mode observed earlier in the bubbling FBC and up to three orders of magnitude lower than in the pulverized coal combustion. Scanning electron micrographs showed few ultrafine particles. The intermediate mode at 0.3 {mu}m consisted of particles irregular in shape, and hence in this mode the particles had not been formed via a gas to particle route. We propose that the 0.3-{mu}m mode had been formed from the partial melting of the very fine mineral particles in the coal. The mass size distribution in the size range 0.01-70 {mu}m was unimodal with maximum at 20 {mu}m. Less than 1% of the fly ash particles was found in the submicrometer size range. 35 refs., 8 figs., 3 tabs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 232522
- Journal Information:
- Aerosol Science and Technology, Journal Name: Aerosol Science and Technology Journal Issue: 3 Vol. 24; ISSN ASTYDQ; ISSN 0278-6826
- Country of Publication:
- United States
- Language:
- English
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