The NOxemitted from a 600 MW unit tangentially fired boiler at full load had a high concentration of about 400mg/Nm3

which can't meet the national requirements of NOxemissions for the utility boilers.Thus

the method combining the advanced hybrid air-staged low-NOxcombustion technology with furnace arrangement was applied to reduce the NOxemission.In addition

by the Fluent software and the realizable k-εmodel

comparison of NOxemissions and pulverized coal combustion process between the original burner structure and the being improved ones was conducted.The flue gas temperature field

velocity field and concentration distribution of CO

O2 and NOxaround the burner area were obtained.The results show that the staged-air combustion can reduce NOx emissions obviously and make the furnace temperature field

velocity field

CO and O2 concentration change correspondingly.The calculation error between the numerical simulation results and the experimental data was less than 5%

indicating the numerical simulation can predict the NOxformation and emission accurately

which provides some theoretical basis for the burners design and operation.