The Effect of Nitrogen on Flame Characteristics in Biogas External Premixed Combustion

摘要

Biogas contains more than 50% methane (CH_4), is a renewable and eco-friendly fuel produced by bacterial action. Not only is biogas flammable but it also contains inhibitors like carbon dioxide and nitrogen, as well as small amounts of H_2, O_2, H_2S and others. Several associated studies have been conducted in order to examine biogas combustion characteristics in external combustion and flame angle, flame height and dimensionless flame height are the important characteristics in external premixed combustion. This research's aims were to discover the influences of N_2 as it is the second most prevalent inhibitor in biogas by burning stoichiometric fuel mixtures (CH_4 and N_2 (0%-50% of fuel)) and oxygen in an experimental external premixed combustion burner whose nozzle tip diameter was 5 mm. The burner was connected to a hose from the oxygen tank and another hose from the fuel tank. Two regulators and flowmeters were placed on each tank to monitor the flow supplied to the mixer and burner. The valves were used to stop or open the fluid supply. The outcome flame propagation is then recorded by a high speed camera and then processed through a computer system. The results indicate that N_2 influenced the flame angle, flame height and dimensionless flame height. The higher the N_2 content inside the fuel, the shorter the flame height and the lower the dimensionless flame height. Moreover, increasing the N_2 content created larger the flame angle.