Page 42 | University of Utah Partnerships | J. Willard Marriott Digital Library

American Flame Research Committee

Contents | 42 of 43

Page 42

Download PDF | | Reference URL | Gallery View | Parent Record

Update Item Information

Title	Low-Temperature Combustion Kinetics of Western Kentucky No 9 Coal
Creator	Daw, C. S.; Krishnan, R. P.
Publisher	Digitized by J. Willard Marriott Library, University of Utah
Date	1983
Spatial Coverage	Akron, Ohio
Abstract	The combustion kinetics of Western Kentucky No. 9 coal were measured in a tubular-flow reactor. The primary objective was to develop a kinetic expression suitable for calculating the combustion rate of devolatilized char in an atmospheric fluidized bed combustor. Coal particles ranging from about 0.64 to 0.033 cm (0.25 to 0.013 in.) diameter were devolatilized and burned in air/nitrogen mixtures at reactor temperatures between 866 and 1090K (1100 and 1500°F) and at oxygen partial pressures between 0 and 0.21 atmospheres. Experiments with subliming naphthalene provided data for correlating the mass transfer between particles suspended in the reactor and the bulk gas stream. This correlation was then combined with the combustion data to separate the two primary rate components: external oxygen diffusion and intra-particle diffusion/reaction. The experimental results demonstrate that combustion of particles of about 0.64 cm (0.25 in.) diameter is almost completely dominated by external diffusion. As particle size is reduced, intra-particle processes rapidly become more important. At sizes less than 0.1 cm (0.04 in.), intra-particle diffusion/reaction is clearly the rate determining step. The intrinsic diffusion/reaction rate (based on external surface area) was found to have an apparent order of 0.6 in oxygen and an effective activation energy of 11.5 kcal/g-mole. It is hypothesized that the unusually low activation energy results from the effect of heating rate on internal surface area and/or catalysis due to inorganic impurities In the char. There is also evidence that the intra-particle resistance to diffusion is very low, requiring a diameter dependent term in the intrinsic reaction rate expression.
Type	Text
Format	application/pdf
Language	eng
Rights	This material may be protected by copyright. Permission required for use in any form. For further information please contact the American Flame Research Committee.
Conversion Specifications	Original scanned with Canon EOS-1Ds Mark II, 16.7 megapixel digital camera and saved as 400 ppi uncompressed TIFF, 16 bit depth.
Scanning Technician	Cliodhna Davis
ARK	ark:/87278/s6765hv2
Setname	uu_afrc
ID	576
Reference URL	https://collections.lib.utah.edu/ark:/87278/s6765hv2

Page Metadata

Title	Page 42
Format	application/pdf
OCR Text	Show REFERENCES I 1. J. W. Wells, R. P. Krishnan, and J. R. Byrd, "Proceedings of the Seventh International Conference on Fluidized Bed Combustion," Philadelphia, 284 (October 1982). 2. M. F. R. Mulcahy and I. W. Smith, Rev. Pure and Appl. Chem. JL9(81) (1969). 3. N. M. Laurendeau, Progr. Energy Combust. Sci, edited by N. A. Chigier, Pergamon Press Ltd., Great Britain, 4, 221-270 (1978). 4. J. R. Arthur, Trans. Faraday Soe. 47_, 164 (1951). 5. I. B. Ross and J. F. Davidson, Trans. Inst. Chem. Eng. (London) ,59, 108 (1981). 6. H. S. Caram, and N. R. Amundson, Ind. Eng. Chem. Fimdam. 16(2) , 171 (1977). 7. E. Mon and N. R. Amundson, Ind. Eng. Chem. Fundam. 17_(4), 313 (1978). 8. C. S. Daw and R. P. Krishnan, Proceedings of Engineering Foundation Conference: Combustion of Tomorrow's Fuels, Santa Barbara, California (November 1982). 9. C. S. Daw and R. P. Krishnan, Combustion Kinetics of Western Kentucky No. 9 Coal, 0RNL/TM-8604 (1983). 10. B. C. Young and I. W. Smith, Proceedings of the Eighteenth Symposium (International) on Combustion) , The Combustion Institute, Pittsburgh, 1245 (1981). 11. R. H. Essenhigh, Chemistry of Coal Utilization, edited by M. A. Elliot, John Wiley and Sons, New York, 1153-1312 (1981). 12. H. H. Sogin, Trans. Amer. Soc. Mech. Engrs. 80, 61 (1958). 13. N. Frossling, Gerlands Beitr. Geophy. 52., 170 (1938). 14. W. E. Ranz and W. R. Marshall, Chem. Eng. Progr. 48, 141, 173 (1952). 15. J. M. Smith, Chemical Engineering Kinetics, McGraw-Hill, 363 (1970). 16. K. K. Pillai, Sn. N. Barket, and A. G. Roberts, "Combustion of Run of Mine Coal in a 12-inch Diameter Pressurized Fluidized Bed Combustor," D0E/MC/14129-1208, Morgantown, West Virginia (1982). 17. J. R. Byrd, Tennessee Valley Authority, Chattanooga, Tennessee, private communication (July 1982). 41
Setname	uu_afrc
ID	574
Reference URL	https://collections.lib.utah.edu/ark:/87278/s6765hv2/574