A two-dimensional theoretical model for the flow and combustion of pulverized coal by diffusion flames is presented. The model predicts gas flows, species concentrations and temperatures. The conservation equations are solved utilizing the κ-ϵ turbulence model. Coal devolatilization is modelled by two-competing-reactions scheme which generates two sets of volatiles and char, each by a specific rate constant which can be described in Arrhenius form, and char combustion from devolatilization occurs by reaction with oxygen, carbon dioxide, and water, and particle dispersion and radiative heat transfer between furnace wall and particles are studied. The model is used to investigate the interaction between flow and combustion in flames produced by arranging the location of primary inlet and secondary inlet. The predictions, which could be valuable for designing furnaces, indicate that an off-center primary inlet, a large recirculation zone, and an asymmetric secondary air inlet are favorable for combustion.