Fly ash formation and penetration through the electrostatic precipitator at PC boilers firing South African and Colombian coals
- VTT Chemical Technology, Espoo (Finland); and others
We have studied in detail the properties of fly ash particles in the size range 0.01 to 100 um formed during the combustion of South African and Colombian coals as well as the fly ash penetration through the electrostatic precipitators (ESP). Both coals were fired at a modern, pulverized coal fired boiler. In addition, South African coal was fired at another boiler. Both boilers were equipped with ABB ESP`s. In addition to standard coal analyses methods, both coals were analyzed with computer controlled scanning electron microscopy (CCSEM) to find more detailed information on the distribution of ash forming constituents in coal. Fly ash number and mass size distributions upstream and downstream the ESP were measured with the differential mobility analyzers and low pressure impactors, respectively. Fly ash upstream and downstream the ESPs was analyzed with CCSEM. Fly ash microstructure was determined with SEM and TEM. Fly ash particle number size distributions at conditions upstream the ESP showed a broad mode at 0.1 to 0.2 um. Electron micrographs showed that these ultrafine particles were chain-like agglomerates having few to several tens of 20 to 50 nm primary particles within each agglomerates Primary particles were mostly amorphous oxides of Al and Si coated with Ca. Particles larger than 0.1 um were spheres having ultrafine Primary particles and agglomerates deposited on the surface. Mass size distributions showed a major mode at 15 um. Only 1 to 2 percent of fly ash was smaller than 0.5 um on the mass basis, i.e. had vaporized during combustion. ESP penetration curves showed clear maxima at 0.1 to 1 um. CCSEM results indicated that supermicron fly ash penetration through the ESP was a function of both particle size and composition.
- OSTI ID:
- 166547
- Report Number(s):
- CONF-9510126-; TRN: 95:008181-0038
- Resource Relation:
- Conference: Annual meeting of the American Association for Aerosol Research, Pittsburgh, PA (United States), 9-13 Oct 1995; Other Information: PBD: 1995; Related Information: Is Part Of American Association for Aerosol Research (AAAR) `95; PB: 464 p.
- Country of Publication:
- United States
- Language:
- English
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