Numerical Simulation on Low NO_x Combustion Technological Transformation of a 600MW Boiler With Opposed Wall Swirling Burners

3-D full-scale steady numerical simulation technique was employed to study on low NOx combustion technological transformation of a 600 MW supercritical boiler with opposed wall swirling burners. Single burner was numerically calculation in advance for the sake of obtaining more realistic inlet boundary setting in the furnace simulation.In order to improve the calculation accuracy by means of undifferentiated connection of boundary condition between burner outlet and furnace inlet with actual spatial distribution of air and pulverized coal, user-defined functions （UDF） was compiled. Compared with past models, computing control domain was extended to whole flow and heat transfer region including boiler level gas flue and tail shaft flue. The results show that O2 concentration reaches wave crest at each centre cross-section of pulverized coal burner layers under baseline condition. Hence, NO concentration increases sharply when flue gas flows through each layer of pulverized coal burners.While the centre cross-sections of pulverized coal burner layers are at lower level in an O2 concentration cycle of fluctuation and adjacent CO concentration peaks with the combination of both annular reverse flow zone and center reflux zone under reconstructive condition, so NO concentration of flue gas in those regions decreases dramatically. Furthermore, this study shows that reasonable low NOx combustion technological transformation scheme exerts no adverse influence on surfaces heat transfer.