Letter | Published:

Control of Reaction Rate in Dust Flames

Naturevolume 187pages11061107 (1960) | Download Citation

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Abstract

EVER since Nusselt1 introduced the boundary layer concept, about forty years ago, for calculating rates of heat and mass transfer to a spherical particle, it has been universally accepted (without proof) by subsequent theoretical work (see ref. 2) that the reaction-rate of particles in a dust flame is determined by the rate of supply of oxygen through a diffusional boundary layer surrounding the particles. That this might not in fact be so was first suggested3 about five years ago, the alternative proposition being that the rate control was chemical, not physical ; the source of the implied error is attributed to the mis-interpretation of reaction data in terms of diffusion instead of chemisorption which, according to Brunauer4, has been a common mistake in the past. Support for the alternative hypothesis, however, has now been provided by analysis of experimental results obtained recently from an anthracite flame.

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References

  1. 1

    Nusselt, W., V.D.I., 60, 102 (1916); 68, 124 (1924).

  2. 2

    (a) Burke, S. P., and Schumann, T. E. W., Indust. Eng. Chem., 23, 406 (1931); 24, 451 (1932). (b) Hottel, H. C., et al., ibid., 26, 749, 889 (1934); 28, 1334 (1936). (c) Spalding, D. B., Proc. Inst. Mech. Eng., 168, 545 (1954). (d) van der Held, E. F. M., Central Technical Institute T.N.O., Delft, Heat Section Report No. 39.

  3. 3

    Essenhigh, R. H., Sheffield Univ. Fuel Soc. J., 6, 15 (1955).

  4. 4

    Brunauer, S., “Adsorption of Gases and Vapours”, 10 (Oxford Univ. Press, 1945).

  5. 5

    Beér, J. M., Thring, M. W., and Essenhigh, R. H., Combustion and Flame, 3, 557 (1959).

  6. 6

    Essenhigh, R. H., and Perry, M. G., Inst. Fuel Conference “Science in the Use of Coal”; Introductory Survey, p. D1 (Sheffield, April, 1958).

  7. 7

    Gulbransen, E. A., and Andrew, K. F., Indust. Eng. Chem., 44, 1034, 1039 (1952).

  8. 8

    Blyholder, G. D., and Eyring, H., U.S. Air Force Office of Scientific Research Report: Technical Note O. A. No. xx (August 1956).

  9. 9

    (a) Essenhigh, R. H., and Thring, M. W., Inst. Fuel Conference “Science in the Use of Coal”, Paper 29, p. D21 (Sheffield, April 1958). (b) Essenhigh, R. H., thesis, University of Sheffield (1959).

  10. 10

    Hottel, H. C., and Stewart, I., Indust. Eng. Chem., 32, 719 (1940). Traustel, S., Feuerungstechnik, 29, 105 (1941). Ledinegg, M., “Dampferzeugung”, 238 (Springer-Verlag, Wien, 1952).

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Affiliations

  1. Department of Fuel Technology and Chemical Engineering University of Sheffield

    • J. M. BEÉR
    •  & R. H. ESSENHIGH

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https://doi.org/10.1038/1871106a0

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