Experimental study of NOx correlation for fuel staged combustion using lab-scale gas turbine combustor at high pressure

The NOx correlation for fuel staged combustion on CH4/air flames was investigated as a function of operating conditions such as pressure, flame temperature, fuel-to-air ratio, and fuel staging ratio. Firstly, the flow characteristics for fuel staged combustion were investigated using particle image velocimetry (PIV) under atmospheric conditions, through which fuel and air mixing was correlated with the turbulence intensity. The turbulent intensity near the burner outlet was strong when the fuel staging ratio (α) was 3%, which provided better fuel and air mixing. NOx correlation for fuel staged combustion was investigated using a lab-scale gas turbine combustor at high pressure. In particular, NOx emissions scale with pressure (NOx = Pn) with n = 0.5 under premix combustion and n = 1.1 for fuel staged combustion. A new NOx correlation for fuel staged combustion is suggested in the form of NOx=a·e(b·Tfl+d·α)·Pn·farc under the operating conditions of real gas turbines.