Modelling of Spontaneous Heating in a Coal Pile.
Proc of the Central States Section of the Comb Inst Combustion Inst 1990 :151-159
A mathematical model of spontaneous heating was developed in support of the U.S. Bureau of Mines research program directed toward the prevention of spontaneous heating in coal piles and/or gobs. This will further fundamental understanding of the process of self- heating of coal such that prevention and suppression technologies can be developed. Reaction kinetics associated with the oxidation of coal were used in a transient thermal transport model of spontaneous heating to estimate the thermodynamic stability of a coal pile of uniform porosity and particle diameter under the assumptions that (1) a spherical zone within the coal pile is initially at a specified elevated temperature and (2) an ambient oxygen supply is maintained in the pile. The effects of particle size and pile compaction upon the spontaneous heating were examined with a one-dimensional transient thermal transport model that allows for oxygen depletion but does not include buoyancy. A specified pressure drop across the pile establishes the gas flow. It was demonstrated that an increase in particle size reduces the maximum coal pile temperature and moves the location of the maximum temperature deeper into the pile. Compaction, through a reduction in the pile porosity, moderates the self-heating of the pile and is a possible method of preventing self-heating in coal piles.
Proc. of the Central States Section of the Comb. Inst; Combustion Inst., 1990, PP. 151-159