Experimental study of the effects of swirl and air dilution on biogas non-premixed flame stability

Abstract

An experimental investigation of the stability limits of biogas in a swirling non-premixed burner has been carried out. A mixture of 60% methane and 40% carbon dioxide was used to reach the typical biogas composition. Vane swirlers with 30°, 45°, and 60° angles were used to make the swirling air. The biogas stability limits and flame behavior under swirling conditions were tested. Besides, effects of air dilution with nitrogen and carbon dioxide on biogas stability limits were investigated. The results show that using swirl can enhance the flame stability limits approximately four or five times comparing to non-swirling air stream. Adding N2/CO2 to the air had negative effects on the flame stability but no changes were observed in the flame structure. The maximum air dilution was also obtained when 27% and 15% N2 was added to the swirling air under strong and weak swirl, respectively.