FLASHBACK PROPENSITY IN SWIRL STABILIZED BURNER WITH SYNGAS FUELS

摘要

In swirl stabilized burner, combustion induced vortex breakdown (CIVB) flashback is a significant phenomenon. This paper presents experimental measurements of CIVB flashback propensity for hydrogen (H_2)-carbon monoxide (CO) flames. The effects of H_2 concentration, and swirl number on the flashback propensity of H_2-CO flames are discussed. For a given air mass flow rate, the stoichiometric ratio (%F) at which the CIVB flashback occurs decreases with the increase in H_2 concentration in fuel mixtures. However it appears that near the CIVB flashback limit, the swirl strength plays a more dominating role over the H_2 concentration in the fuel mixture. The flashback propensity decreases with the increase in swirl number. An analysis of the nonreacting flow field (Air 6 g/s) as well as reacting (CH_4-Air and H_2-CO-Air) flame near the CIVB transient velocity field was conducted. The analysis revealed that a complex vortex- chemistry interaction leading to vortex breakdown and flashback occurred. The vector flow field showed that the high swirling flow generates a more stabilized and wider recirculation zone. It also showed that the presence of H_2 dictates the intensity of the flashback process.