Combustion characteristics of low-concentration coal mine gas with metal fiber burners

Coal mine gas with methane concentration lower than 30 % is regarded as low-concentration gas. Currently, both domestically and internationally, coal mine gas with methane concentration ranging from 10 % to 30 % is mainly used for power generation. However, it is not easy to safely combust and treat coal mine gas with methane concentration below 10 %, which is typically directly emitted into the atmosphere, leading to energy wastage and environmental pollution. Metal fiber burners are a type of porous medium burner, suitable for fully premixed combustion, enabling the safe utilization of low-concentration gas within the explosive range. In this study, a direct combustion experimental system was designed to investigate the combustion characteristics of low-concentration coal mine gas with metal fiber burners. The results show that with an increase in the porosity and thickness of the metal fiber woven fabric, the range of area heat release rate expands, and the load adjustment ratio increases, enlarging the range of stable combustion. Single-layer woven fabric burner ignite more easily, followed by double-layer woven fabric burner, while non-woven fabric burner are the least prone to ignition. The results also indicate that when using metal fiber burners to combust low-concentration gas, the emissions of NO_x and CO in the flue gas remain at lower levels.