Study Of Combustion Processes And Emission Of NOx In 600 MW Tangentially Fired Boiler

In order to reduce the emission of NOx, Use air classification method to transform the boiler. Use CFD to simulate the Status of combustion and form of NOx before and after transformation. Analyze the reason caused the different formation of NOx before and after transformation by spatial distribution method on global and local.The result shows that after transformation. the radius of the inscribed circle decreases a little. It’s good for decrease the slagging and high temperature corrosion. The concentration of the O2 become lower and the concentration of the CO increase in the main combustion region. The input of the SOFA increase the concentration of the O2 in the burnout region, It’s good for the burnout of the coke.Analyze the NOx generate characteristic, start from the factors which affect the fuel NOx and thermal NOx. Study the influence of the volatile、HCN and coke for the fuel NOx. Study the influence of the O2 and temperature for the thermal NOx. The result show the difference of the distribution of the rate of the volatile is low. It focus near the outlet of the burner. It affect the distribution of the high magnitude rate of the fuel NOx. After transformation, the oxidation of the HCN become lower because of the lack of O2. The same magnitude,after transformation the mole fraction of the HCN distribute more widely than before transformation. The region for fuel NOx and thermal NOx formation is different. Along with height of the boiler, the concentration of the NOx before transformation change a little. Only when the OFA input, it will increase sharply. But after transformation the concentration of NOx is different. It generally has a tendency to rise. Especially when the OFA and SOFA input, the NOx increase sharply. In the end.it affect the final emission of NOx. From the comparison of the key parameters, we can get the temperature of the outlet is higher than before transformation. The incomplete combustion losses has increased, and the final emission of the NOx decrease sharply.