Extinction limits of counterflow diffusion flames of CO, H₂, CH₄ and their blends

An experimental study on extinction limits of counterflow diffusion flames of CO, H₂, CH₄ and their blends, and high-temperature air ≤ 773 K mixed with H₂O was performed using a Tsuji burner to examine combustion characteristics of mixed fuels produced by incinerators. CO flames mixed with a small amount of H₂ emitted a luminous blue-white light in room-temperature air. In high-temperature air, CO flames were thick and emitted a bright blue-white light surrounded by thin red, which is the thermoluminescence of H₂O vapor resulting from heating by high-temperature airflow. In high-temperature O₂ and H₂O oxidizer, CH₄ flames were thick and emitted a bright luminous red because of the large amount of H₂O vapor emitted by the flame. The calculated results were generally consistent with the experimental results, indicating that the extinction limit increased by nearly one order when the air temperature increased from a room temperature of 300 K to a high temperature of 773 K for CH₄ diffusion flame. Since CO as a fuel cannot burn in dry air, the extinction limit for (CO + N₂)/air diffusion flame increased with H₂ content in fuel. Original is an abstract.