Mathematical modeling of reactants’ transport and chemistry during oxidation of a millimeter-sized coal-char particle in a hot air stream

A two-dimensional time-dependent model for mathematical description of the oxidation process of a coal-char particle placed in an oxidizer stream has been developed. The model is used to simulate the oxidation process of a 5.2 mm char-particle for which the kinetic parameters for heterogeneous reactions have been measured. The initial morphology has been determined using mercury porosimetry. The calculated char-particle mass-loss agrees well with the measured data and the model predicts slower oxidation rates at the end of the process due to alterations to the particle morphology. The importance of both the Boudouard reaction and CO₂ diffusion inside the particle has been underlined.