Experimental analysis of oxygen-methane combustion inside a gas turbine reactor under various operating conditions

The oxygen-methane diffusion flame taking place in a gas turbine reactor was investigated experimentally with emphasis on flame stability. The oxidizer is a mixture of O₂ and CO₂ and the oxy-combustion process was studied at different equivalence ratios ranging from Φ = 0.5 to 1.0 and different O₂/CO₂ mixture composition (100/0, 80/20, 60/40, 50/50, 40/60, 30/70 and 25/75). The flame blowout condition was achieved through the reduction of oxygen percentage in the oxidizer mixture. Measurements were obtained for the flue gas temperature and concentration as well as flame visualization. It was found that the flame is very stable at the equivalence ratio of 0.65. At this ratio, the flame blows out at an O₂/CO₂ blending ratio of 22/78 for the case of fuel flow rate of 6 L/min and at a blending ratio of 21/79 for the case of fuel flow rate of 9 L/min. Attempts for operating the burner with less than 21% O₂ were unsuccessful at all ranges of the operating parameters and resulted in unstable operation and blowout. Moreover, it was observed that the stabilization behavior did not change significantly with the variation of the fuel volume flow rate. It was also found that both flame and flue gas temperatures are reduced with the increase of the equivalence ratio.