Abstract: The present study on coal-fired coupled sludge power generation technology mainly focused on the influence of mixing ratio,but the effects of factors such as the excess air coefficient in the main combustion zone are still unclear. In view of this point,the eddy dissipation model was used to simulate the municipal sludge combustion in a 600 MW tangentially fired boiler. The effects of sludge blending ratio,excess air coefficient in the main combustion zone and secondary air distribution mode on the sludge mixing combustion and NOxgeneration characteristics in coal-fired boiler were analyzed. The results show that as the sludge blending ratio increases,the overall temperature of the furnace decreases,which affects the stability of combustion,and the NOxconcentration at the outlet of the furnace decreases. When the blending ratio of sludge increases to 20%,the furnace outlet temperature drops by about 100 K,and the NOxconcentration decreases by53.2%. However,the blending ratio has little effect on the velocity field distribution in the furnace. As the excess air coefficient of the main combustion zone increases from 0. 72 to 0. 96,the furnace outlet temperature increases slightly,only by about 15 K,while the NOxconcentration increases significantly,from 174.39 mg/m3 to 352.09 mg/m3,which is about an increase of 50.4%. Within the range of excess air coefficient in this paper,considering temperature and NOxconcentration,it is recommended that the excess air coefficient of the main combustion zone is 0.84. The influence of different secondary air distribution on the co-combustion of sludge in coal-fired boilers is quite different. In the five air distribution modes,the furnace outlet temperature and NOxconcentration change greatly. The furnace outlet temperature under the condition of air distribution at the waist is the lowest at 1 289 K,while the inverted tower air distribution temperature is the highest at 1 341 K. At the same time,the NOxconcentration of the drum waist air distribution is higher,which is 207.77 mg/m3,and the beam waist air distribution is lower,which is 156.42 mg/m3. Considering the temperature and NOxconcentration,the secondary air distribution is recommended to adopt the beam waist distribution mode.