Combustion Science and Technology, Vol.175, No.3, 523-544, 2003
Computational modeling of NOx reburning by hydrocarbons in a coal furnace with reduced kinetics
Reduction technology of kinetic mechanisms has greatly increased the possibility of the detailed kinetic modeling of practical combustion problems and offers potential improvement of modeling accuracy in comparison with using global mechanisms. The current work applies a mechanism-reduction technology in conjunction with the CHEMKIN library and develops a reduced kinetics for NOx reburning with methane in coal-fired furnaces. Based on the full mechanism GRI 3.0 with 325 reactions and 53 species, a 38-species/100-reaction skeletal mechanism, and, further, a 16-species/12-step reduced mechanism were established. The reduced mechanism was implemented into the three-dimensional Computational Fluid Dynamics (CFD) program AIOLOS, which deals predominantly with pulverized-coal combustion processes. The eddy dissipation concept (EDC) model was used to consider the influence of turbulence on chemistry. A simulation series of the CH4 reburning process in a coal-red reactor was carried out. The modeling results are discussed and compared with experimental data. It is shown that the reduced mechanism and the comprehensive modeling give quite satisfactory results in a fairly wide parameter range, and that the computing time of the current reduced mechanism is approximately three times that using the traditional global mechanism.