Abstract: The combustion process of LNASB burner is numerically studied in a 600 MW supercritical boiler with realizable k-ε model. The effect of fuel feeding on the burner, NO distribution inside the furnace on different secondary air flow and excess air ratio are researched, the characteristics of NO formation of the burners with the improved structure and the original structure are compared. Numerical simulation results show that the inner secondary air has great influence on NO, when the inner secondary air is shut down, NO at furnace outlet decreases 22%. The excess air ratio of the main burner region has significant influence on the NO formation, when the excess air ratio is small, there is less NO formation in the boiler. Central fuel feeding can effectively reduce NO formation. With full load input into five-layer burners, NO will be reduced by 16%, the result of numerical calculation can provide the theoretical basis for the formation of NO, and it agrees with the experimental result. Through equipment improvement and combustion adjustment, the boiler NO emission can be effectively controlled, thus providing a theoretical basis of reducing NO for LNASB burner design and operation.

Key words: Central fuel feeding, LNASB burner, Numerical simulation, Realizable k-ε model