In order to study the influence of different types of biomass and the excess air coefficient in the reburning zone on the combustion process of coal-fired coupled biomass gas

the re-burning processes of a 600 MW tangentially-fired boiler coupled with two 20 t/h gasifiers have been simulated by Fluent software. The effects of straw gas

food waste gas and biogas on the temperature field

composition field and NO_x emissions at the furnace outlet under the conditions with the excess air coefficient of 0.7

0.8 and 0.9 in the re-burning zone were studied. The results show that

biomass gas re-burning can reduce the coal consumption of the boiler and the combustion temperature in the main combustion zone

but the center of the combustion flame in the furnace is moved upward

which increases the temperature of the flue gas at the outlet of the furnace. Biomass gas re-burning can improve the problem of boiler pollutant emissions effectively

the higher the content of hydrocarbon compounds in the biomass gas

the better the effect of reducing nitrogen oxide emissions. The nitrogen reduction effect of straw gas

food waste gas and biogas re-burning increases sequentially

the nitrogen reduction rate of biogas re-burning can reach up to 41.20%.When the excess air coefficient in the re-burning zone is in the range of 0.6～0.8

the biomass gas re-burning system has the best pollutant emission effect. When the excess air coefficient in the re-burning zone continues to increase

the nitrogen reduction effect becomes worse gradually.