| Nitrogen oxides release through coal burning pays a bad influence on the environment, which is largest source of air pollution in China. NOx release is one of the main factors of acid rain, photochemical smoke which is bad for human health, which atracting more and more attention. NOx releases control is not very popular in power station in China, so that there is significant in the study of low NOx releases eficiently.In this paper, the low NOx combustion technology based on BFA and OFA is studied by the way of experiment and numerical simulation to analyze how to obtain higher efficiency in furnace, while it doesn't make the safety and economy reduced.The physical flow model which is narrowed by 15 times is used to research on the aerodynamic field characteristics while put BFA and OFA into combustion system through quantitative measurement of the furnace velocity field. The test results show that:(1) there is apparent circle diameter of counterclockwise tangential flow field, and area of round increases gradually with the furnace chamber higher. (2) The tangential circle's relative diameter of the first layer's primary air section increase from 0.5 to 0.66 along with the increase of BFA wind speed from 0 m/s to 25 m/s,。(3) The tangential circle's relative diameter changed a little as the speed ranged from 0 to 16m/s, but when the speed increased to 25 m/s, the relative diameter of tangential circle decreases sharply, from 0.72 reduced to 0.55。(4) The mainly area which produces NOx below primary air region divided into two parts:low temperature oxidation zone and reducing area. Injecting BFA wind can simultaneously reduce NOx output of the two areas, thereby reducing the overall NOx output of the boiler.Besides, using CFD software FLUENT 6.3 and selecting proper mathematical model to get the numerical simulation result of furnace flow, heat transfer and combustion by the new NOx release technology of BFA and OFA in the 420t/h pulverized coal-fired boiler. The results show that:(1) before modification, down-primary air section tangential relative diameter is 0.3319.When Furnace height increases, tangential relative diameter also increases. At the first 8 section, diameter increased to 0.5299. After the transformation, the relative diameter in the plan A and B is 0.5099 and 0.5002 respectively, increased by 53.5% and 50.7%, which is consistent with the results obtained under the cold die experiment (2) tangential relative diameter is 0.3752 and 0.4377 respectively in the plan A and C which is injected OFA wind. The diameter reduced by 29.2% and 17.4, than before. The conclusion shows that OFA wind jet has enough momentum to penetrate the main flue gas then produces strong disturbance, which can make the rotation speed and the rotating rigid of tangential round increase. The trend that diameter reduced is meet with the experimental results obtained by the physical flow model. (3) After using low NOx emissions technology combined by the furnace NOx emission in the exit reduced by about 30%. CO concentrations have been close to zero in the exit of the furnace, explaining the low NOx combustion technology will not affect the burn out rate of pulverized coal.
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