The effect of applying mine ventilation air methane as primary and secondary air on coal combustion was numerically studied for a 2 027 t/h tangentially coal-fired boiler. After verifying the feasibility of model

the influences of volume fraction of the ventilation air methane(VAM) on furnace temperature and emission characteristics of NOx were investigated. The results show that

with an increase in volume fraction of the methane in the air

the average temperature in the main combustion zone increased by 53 K at the most

while the concentration of NO and O2 in the furnace and burnout rate of the coal decreased. The CO concentration changed in the opposite. The average concentration of NO at the furnace outlet decreased from 388.21 mg/m3 to 318.88 mg/m3

by 17.8%. It can be concluded that applying mine ventilation air methane as primary and secondary air of the boiler can reduce the NOx emission effectively.