N₂ formation from coal nitrogen during pyrolysis and combustion

Four kinds of native coals were applied to investigate for N₂ formation from coal nitrogen during pyrolysis or combustion with a gas chromatographic analysis system. The experimental results show that a part of coal nitrogen can be converted into N₂ during pyrolysis. The percentage of N₂ formation from fuel nitrogen is highest for Shenmu and lowest for Jiaozuo coal. N₂ formation percentage formed increases with the increase of temperature. During coal combustion, N₂ can also be formed from coal nitrogen, and N₂ formation percentage also depends on temperature. The percentage of N₂ formation from coal nitrogen increases with temperature at the temperature lower than or equal to 900°C for the coals studied while it decreases obviously at 1100°C except Shenmu coal. The minerals in the coals studied can enhance the N₂ formation whether during pyrolysis or during combustion process. The percentage of N₂ formation during low temperature combustion is greater than that during low temperature pyrolysis while it depends on coal types at 1100°C.