Abstract: The combustion process of a 1 000 MW ultra-super critical boiler is numerically studied with realizable k-ε model. NOx emission are compared between the original and being improved burner structure. The effect of over-fire air ratio, after air port (AAP) and side air port(SAP) air ratio, burner running type and load conditions are analyzed after burner combustion stability characteristic being improved. Simulation and analysis results indicate as follows: Burner flow and temperature field change significantly after combustion stability characteristic being improved, the same as burner with oil-free ignition equipment. NOx emission has no obviously increase; The furnace can be separated into four zones according to change rule of NOx along furnace height direction, NOx density fast increasing zone, density slow decreasing zone, density fast decreasing zone and density gradual increasing zone; NOx emission will decrease after over-fire air ratio decreases, and the same as AAP and SAP air ratio being increased conditions; The same load condition, NOx emission is less when more burners at down part of the furnace are put into running. The numerical simulation and the experimental datas were compared when the burner of original and being improved structure, the difference is less than 10%, numerical simulation results accurately predict NOx generation and emission of the burner being improved structure, which provide some theoretical basis for the burner design and operation.

Key words: Combustion stability, HT-NR3 burner, NOx emission, Numerically studing, Realizable k-ε model, Fuel cell system, Tram, Cooling system, Low noise