Numerical Simulation of NOx Emission in a Rotary Kiln During Coal Combustion and Co-combustion of Coal and Natural Gas

Numerical simulation of NOx emission in a rotary kiln was carried out. In order to reduce NOx emission, the cases of coal combustion and co-combustion of coal and natural gas were compared. The gas phase is expressed with two-equation model, while the combustion with non-premixed model and the radiation with P-1 radiation model, and the NOx emission with the NOx model. The results show that, the NOx density distribution of coal combustion has a special zone with the highest NOx density, according to its high temperature zone. Furthermore, the NOx emission amount of co-combustion is lower than that of coal combustion alone.