Combustion Characteristics of Coal Mine Methane in a Preheated-Burner Packed with Raschig Rings

The utilization of coal mine methane (CMM) through porous medium combustion (PMC) contributes to energy saving and environmental protection. In this paper, a double-layer porous medium burner with the combination of heat exchangers was designed to recycle the exhausted heat for preheating the inlet gas. The effects of Raschig ring sizes on the temperature distributions and pollutant emissions were studied under different operating conditions. The results indicate that the preheating of inlet gas greatly influenced the temperature distribution and the optimum preheating effect was shown in the burner of spiral heat exchanger together with lower pollutant emissions. With the increasing of inlet velocity and equivalence ratio, the peak temperature was increased significantly. As the Raschig ring size increased, the flame temperature increased first and then decreased gradually. Meanwhile, the highest temperature and lowest average emissions of NOx and CO appeared in the burner of 10 mm Raschig rings. This study will provide the CMM utilization engineering with the theoretical foundation on PMC.