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Laser Ignition of Levitated Char Particles

Wong, Brian A. and Gavalas, George R. and Flagan, Richard C. (1995) Laser Ignition of Levitated Char Particles. Energy and Fuels, 9 (3). pp. 484-492. ISSN 0887-0624. https://resolver.caltech.edu/CaltechAUTHORS:20151007-090426721

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Abstract

The temperature history of a char particle that was heated by a carbon dioxide laser to the ignition point was studied in the electrodynamic balance. The ignition characteristics of char particles are an important part of the overall coal combustion process, and the aim of research in this area is to improve efficiency and minimize waste products and pollution in current combustors. The experiments were conducted using 158-210 µm diameter Spherocarb particles, and 200-300 µm diameter char particles from a bituminous coal. Individual charged char particles were suspended in the electrodynamic balance and heated by a 420 ms pulse of radiation from a CO_2 laser at a heating rate of approximately 4.5 x 10^3 K/s. The temperature of the particle was measured with an optical pyrometer. The atmosphere in the electrodynamic balance was initially pure nitrogen. The oxygen concentration was slowly increased as successive laser pulses were applied, until the particle ignited. Upon ignition, the particle lost charge and dropped from the center of the balance. The particle temperature profile preceding ignition shows the ignition delay predicted by the general ignition condition of Semenov's thermal explosion theory. The measured temperature traces could be described well by calculations treating the particle as a sphere and using rate parameters given in the literature.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/ef00051a013DOIArticle
http://pubs.acs.org/doi/abs/10.1021/ef00051a013PublisherArticle
ORCID:
AuthorORCID
Gavalas, George R.0000-0003-1468-6835
Flagan, Richard C.0000-0001-5690-770X
Additional Information:© 1995 American Chemical Society. Received September 6, 1994. This research was supported by the US. Department of Energy University Coal Research Program under grant DE-FG22-89PC89765. Presented in poster form at the 10th annual meeting of the American Association for Aerosol Research, Traverse City, MI, October 7-11, 1991.
Funders:
Funding AgencyGrant Number
Department of Energy (DOE)DE-FG22-89PC89765
Issue or Number:3
Record Number:CaltechAUTHORS:20151007-090426721
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20151007-090426721
Official Citation:Laser Ignition of Levitated Char Particles Brian A. Wong, George R. Gavalas, and Richard C. Flagan Energy & Fuels 1995 9 (3), 484-492 DOI: 10.1021/ef00051a013
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:60848
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:13 Oct 2015 21:30
Last Modified:03 Oct 2019 09:01

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