Experimental Studies of NOx Emissions in Sequential Fuel Combustion with a Diffusion Second Zone

This is the third paper on experimental research and optimization of combustion in the fuel-air mixture in the two-zone combustor at outlet gas temperatures of 1550-1700 degrees C with meeting the requirements for harmful substances (NOx and CO) emissions. The experimental results on combustion of gaseous fuel in the combustor with two consecutive combustion zones are presented. Each zone has its own burner: the first burner is traditional and located at the end of the flame tube, while the second burner is sequential and located downstream on side walls of the flame tube. Fuel combustion in the second zone occurs at a low oxygen content and high temperature. Zones with maximal CO values are shown to be formed near the flame tube walls, while maximal NOx concentrations are observed in the central zone of the flow recirculation. The penetration capacity of the fuel jets entering the second combustion zone was evaluated, and the jet trajectories in the blowing flow of hot gases in the first zone are shown. The results of optimization of the fuel distribution between two successive combustion zones, as well as the effect of the flow rate on the NOx and CO formation at the outlet gas temperature of 1550-1700 degrees C, are presented. The results were obtained by testing the model low-emission combustor at the test facility of the All-Russia Thermal Engineering Institute.