Research on the secondary air position for the one-dimensional model of low NOx combustion.

This study developed a new model of low NOx combustion for the direct flow of pulverized coal, which enabled the relationships among gas temperature, oxygen concentration, time consumption, and distance to be investigated. A model of the ignition and combustion zone was discussed in detail. It was shown that the gas temperature and the oxygen concentration change with the distance. The proper position of the secondary air injection can be obtained according to the gas temperature and the oxygen concentration which significantly affect NOx formation. The model can be used to determine the injection position of the secondary air for the design or modification of boilers for low NOx coal combustion. Application of the model to a power plant boiler together with pre-ignition model and reburning technology enabled an overall 48% reduction of NOx to be obtained. [ABSTRACT FROM PUBLISHER]