Numerical Investigation of Influence of Dilution in Air and Fuel Sides onMILD Combustion

Understanding of how and where NOx formation occurs is very important for efficient and clean operation of utility burners. FGR1 and FIR2 are new methods adopted to control NOx formation in combustion chamber. In this methods flue gas decreases flame temperature and reaction rate, resulting in the diminish in thermal NOx emission. In the present study, the MILD3 combustion burner have been simulated, and result validated with experimental data. In order to modification, variations including temperature and flow of air inlet are performed. Also the effect of FGR/FIR methods on NOx reduction by using CO2, H2O, and N2 as diluents gases are investigated. Results show that FIR is more effective to reduce NOx emission than FGR, and H2O dilutor due to large specific heat, is more effective to reduce NOx product compared to CO2 and N2 diluters. Also with increasing the velocity and flow of air inlet, the thermal NOX concentration decreases.

Keywords:

MILD Combustion , CFD , Flue Gas Recirculation (FGR) , Fuel Induced Recirculation (FIR) , NOx Emission