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

At present, the utilization rate of low-concentration coal mine gas within the explosion limit is low at home and abroad, and it is usually discharged directly into the air, which inevitably causes energy waste and environmental pollution. In this paper, the metal fibre burner was used to treat low concentration coal mine methane. A metal fibre combustion system was designed and built to study its combustion stability, anti-backfire, and emission characteristics. The experiments showed that the metal fibre burner could achieve stable combustion when burning mixed gas with methane concentration of 6%-10%. As the methane concentration increased, its load regulation ratio (the ratio of the maximum heating input to the minimum heating input) increased from 28 to 46, which was much greater than the conventional fully premixed burner. The maximum flame temperature of the metal fibre burner was 1181.4°C, while the maximum temperature of the wall inside the burner was 79.8°C, which would not lead to a flashback, effectively demonstrating the anti-backfire characteristics of the metal fibre as woven fabric and the safety of the combustion system. The pollutant emission was measured and, under normal working conditions, the highest NOx emission was 50ppm, the highest CO emission was 8ppm, and the highest CH4 emission was 3483ppm. After using metal fibre weaving, the highest NOx emission was 28ppm, the highest CO emission was 3ppm, and CH4 emission was up to 54ppm, so the use of metal fibre fabrics can reduce pollutant emissions.