A numerical model is presented and simulations are performed for the pyrolysis of a single coal particle. The governing equations are derived based on a volume-averaged formulation of flow of fluids inside a porous media. All transport properties of the coal material needed in the model was obtained from literature. In order to understand different regimes of pyrolysis in a large coal particle, a scaling analysis is performed and all relevant nondimensional numbers were obtained. A solution algorithm is proposed for the system of governing equations. In the numerical model, a special treatment of the mass source term (release of volatile gasses) is proposed which is based on the data obtained from TGA experiments on coal pyrolysis. This reaction model is an alternative to the Arrhenius type of formulation which is frequently used in the modelling of the pyrolysis reaction with very limited success. Model results are presented for pyrolysis at different magnitudes of the Biot number. Results are compared with experimental data obtained from TGA experiments performed at different rates.