The mechanism for laminar dust flame propagation can only be elucidated from a comprehensive mathematical model which incorporates conduction and radiation, as well as the chemical kinetics of particle devolatilization and gas phase and char reaction. The mathematical model for a flat, laminar, premixed coal-air flame is applied to the atmospheric coal-air mixtures studied by Smoot and co-workers, and comparisons are made with their measurements and predictions. Here the principal parameter for comparison is the laminar burning velocity. The studies of Smoot and co-workers are first reviewed and compared with those predicted by the present model. The effects of inlet temperature and devolatilization rate constants on the burning velocities are studied with the present model, and compared with their measurements and predictions. Their measured burning velocities are approximately predicted with the present model at relatively high coal concentrations, with a somewhat increased inlet temperature. From the comparisons, their model might over-estimate particle temperature and rates of devolatilization. This would enable coal-air mixtures to be burned without any form of preheat and would tend to increase their computed values of burning velocity.

The combustion tests for Korean anthracite-bituminous coal blend were carried out in the 200 MW utility boiler. The burning characteristics of the blend were studied with a thermogravimetric analyzer (TGA). From the observation of TGA burning profiles, it was found that the presence of bituminous coal in the blend appeared to enhance the reactivity of anthracite in the higher temperature region, indicating certain interactions between the two coals. The plant test showed the boiler operation was reasonably stable with somewhat poor combustion efficiency, and some modification of the combustion environment in the furnace is necessitate for the further stable plant operation.