Experimental study on the oxygen-enriched biogas explosion characteristics by co-firing propane in a duct

Abstract

To demonstrate the effect of propane co-firing on the explosion characteristics of the oxygen-enriched biogas, deflagration experiments were conducted in a semi-open duct. The results show that the tulip flame transforms from an existence to a disappearance with increasing oxygen fraction. The increasing brightness of the flame indicates that the increase in oxygen fraction can enhance the explosion strength and accelerate flame propagation. A clear backward motion of the burnt gas is clearly distinguished in the direct imaging of flame propagations. The propane effect is discernible when the flame evolves in a dynamic manner shortly after the flame skirt is in touch with the sidewalls. Moreover, the oxygen fraction impacts the extent of this dynamic feature and thus the magnitude of the propane effect. The laminar burning velocity SL can be singled out to forecast the flame propagation speed. The propane effect on SL and [H+OH+O]max gradually strengthens with increasing oxygen enrichment. [H+OH+O]max is well related to the fundamental properties of the mixture, such as SL, the expansion ratio, initial temperature and flame thickness, which in turn dominate flame propagations in the duct.