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Flame front stability of low calorific fuel gas combustion with preheated air in a porous burner

Wang, Guanqing, Tang, Pengbo, Li, Yuan, Xu, Jiangrong, Durst, Franz
Energy 2019 v.170 pp. 1279-1288
air, air temperature, aluminum oxide, ambient temperature, burners, ceramics, combustion, foams, fuels, heat, models, porous media
The flame front stabilization of low calorific fuel gas (LCFG) combustion with preheated air was investigated numerically in a burner filled with Al2O3 ceramic foams. A two-dimensional model was implemented to simulate the flame propagation process of methane–preheated air combustion at an extra-low equivalence ratio. In addition to the wall heat loss, the effects of the preheated air temperature were analyzed by focusing on the flame front inclination and propagation velocity. The flame front instability for room temperature air agreed well with the results of the corresponding experiments. The results show that an increase in the preheated air temperature helps to improve the flame stabilization, such as inhibiting flame front inclination, decreasing its propagation velocity, and increasing the maximum combustion temperature. A stable combustion flame can be realized for LCFG by preheating the air to a critical temperature, which decreases with increase in the equivalence ratio and decrease in the inlet velocity. The wall heat loss promotes the flame front inclination, whereas it has little effect on its propagation velocity for stable combustion. The results are conducive to clean combustion of LCFG in porous media, and helpful for the design and operation of porous burners.