Studies on NOx emission in a natural gas pilot boiler with internal flue gas recirculation

Experimental and numerical simulation methods were adopted to study natural gas combustion in a pilot boiler. The effect of internal flue gas recirculation on NOx emission was investigated. Experimental and numerical simulation results give temperature, oxygen concentration, NO concentration at the entrance of the chimney of the pilot boiler. Experiment results show that the central pipe is beneficial to reduce NO emission. With the central pipe in the pilot boiler, the measured temperature at the entrance of the chimney is lower than that without the central pipe, which means more heat loss in the pilot boiler, and this indicates that the heat transfer is enhanced by the central pipe.