Study On The Nitrogen Emission Characteristics And Sulfur Nitrogen Interactions During Coal Combustion

China is a country with plenty of coal resource and the energy consumption mainly depends on coal. There is a lot of nitrogen oxide released during coal combustion, this may lead to serious environmental pollution and it also has severe impact on our health. So it is of great importance to investigate the regulars of fuel nitrogen emission during coal combustion in order to control pollutant emission and realize clean combustion of pulverized coal.First of all, the nitrogen releasing characteristics of different coals combusted were studied. The main nitrogen oxide product NO was detected and analyzed. It was found that nitrogen emission is strongly affected by the combustion condition: the conversion rate of fuel nitrogen is increased with increasing oxygen concentration and higher temperature. But when the oxygen concentration or the temperature increased to a certain extent, the increasing trend of the fuel nitrogen conversion rate becomes gentle. It was also found that the fuel nitrogen conversion rate appears to be different with different coals: this conversion rate is increased with higher volatile content and is descendent with higher nitrogen content although in this instance the instantaneous concentration of NO is increased.Next, numerical calculation of fuel nitrogen emission during coal combustion was carried out and mathematical model of forecasting coal emission was built. Fu-Zhang universal model, diffusion-dynamical controlling combustion and De'Soete model were separately adopted for devolatilization, char combustion and NO formation. It was indicated that the conversion rate of volatile nitrogen and char nitrogen all increase with higher temperature and the conversion rate of volatile nitrogen is much higher than that of char nitrogen at higher temperature. The final calculated result of the model is accordant with the experimental value, so it could be thought that the mathematical model may be used to forecast nitrogen conversion rate during coal combustion correctly.Finally, the research of interaction between sulfur and nitrogen during coal combustion was carried out. The following results were achieved according to the experiment: The formation of NO is inhibited by the addition of sulfur element, but the influence is not the same for different rank of coals. The interaction between sulfur and nitrogen is more severe for coals with higher volatile content. The nitrogen conversion rate descended when the soluble mineral substance was removed by acid-washing. It is obvious that the mineral substance removed by acid-washing has important catalysis effect. When the pyrite was removed, the nitrogen conversion rate descended further more. That is to say the pyrite in the coal also has some promoting action on NO formation. There is also important affection on nitrogen emission of SO₂ addition: in the oxidizing atmosphere, the nitrogen conversion rate descends with SO2 addition, but in reducing atmosphere, it is just the opposite. Sulfur emission is also affected by NO addition. The concentration of SO2 was increased during combustion of Sample 6.This thesis explores nitrogen releasing characteristics and sulfur nitrogen interaction during coal combustion. It is hoped that there is some basal action on the development of low NO_x combustion technique and synergism desulfurization-denitrification technique.