Theory of Idealized Coal Devolatilization

  • P. A. Libby


The aerothermochemical interaction between a devolatilizing coal particle and its ambient is studied by means of an idealized model consisting of two solid-phase species, which thermally decompose to yield a single gas-phase species. Devolatilization is described by a classical linear theory involving both equilibrium and kinetic characteristics of each solid-phase species. The temperature history of the particle is treated in two different ways reflecting different experimental and applied situations. One simulates the direct heating of a particle, e.g., on a wire grid, so that the temperature history is prescribed. The second relates to injection of a cold particle into a hot ambient either under experimental conditions or in an entrained flow reactor. In the second situation both a frozen gas phase corresponding to devolatilization in inert ambients and equilibrium chemistry in the gas phase as described by a flame-sheet model are discussed. It is concluded that, despite the high degree of idealization involved in the analysis, a large number of thermochemical parameters, some with uncertain values, enter the description of particle behavior. It is difficult to determine kinetic data from direct heating experiments. The thermal response of a cold particle injected into a hot ambient is sensitive to the kinetics of devolatilization and to the heats of pyrolysis.


Particle Temperature Temperature History Coal Particle Particle Behavior Coal Char 


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Copyright information

© Plenum Press, New York 1985

Authors and Affiliations

  • P. A. Libby
    • 1
    • 2
  1. 1.Department of Applied Mechanics and Engineering SciencesUniversity of California San DiegoLa JollaUSA
  2. 2.Systems Science and SoftwareLa JollaUSA

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