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HIGH TEMPERATURE INTERACTIONS BETWEEN RESIDUAL OIL ASH AND DISPERSED KAOLINITE POWDERS
Citation:
Linak*, W P., C A. Miller*, J P. Wood, T. Shinagawa, J. Yoo, D. Santoianni, J. L. Wendt, AND Y. Seo. HIGH TEMPERATURE INTERACTIONS BETWEEN RESIDUAL OIL ASH AND DISPERSED KAOLINITE POWDERS. AEROSOL SCIENCE AND TECHNOLOGY. Taylor & Francis, Inc., Philadelphia, PA, 38(9):900-913, (2004).
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Description:
The potential use of sorbents to manage ultrafine ash aerosol emissions from residual oil combustion was investigated using a downfired 82-kW-rated laboratory-scale refractory-lined combustor. The major constituents were vanadium (V), iron (Fe), nickel, (Ni) and zinc (Zn). Of these only Zn is considered to be semi-volatile in the classical sense. The overall ash content of residual oil is very low, resulting in total ash vaporization at 1800 K with appreciable vaporization occurring at temperatures as low as 1400 K. Therefore, the possibility of interactions between ash vapor and sorbent substrates exists. Kaolinite powder was injected at various locations in the combustor. Ash scavenging was determined by differences in the area under the ultrafine portion of the particle size distribution (PSD), as measured by a scanning mobility particle sizer. Impactor samples and x-ray fluorescence (XRF) analyses supported these data. In general, injection of kaolinite sorbent was able to capture up to 50% of all the ash in the residual fuel oil. Captures of 30% were more common when injection occurred downstream of the combustion zone, rather than with the combustion air into the main flame. Without sorbent addition, baseline measurements of the fly ash PSD and chemical composition indicate that under the practical combustion conditions examined here, essentially all of the metals contained in the residual oil form ultrafine particles (on the order of 0.1 micrometer in diameter). Theoretical calculations showed that coagulation could explain, at most, 5% of this interaction. Hence, the data suggest that kaolinite powders reactively capture most of the vapor phase metals. Mechanisms and rates still remain to be quantified.
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HIGH TEMPERATURE INTERACTIONS BETWEEN RESIDUAL OIL ASH AND DISPERSED KAOLINITE POWDERS