Low-concentration methane(LCM) has been one of the biggest difficulties in using coal mine methane.And previous studies found that premixed combustion in porous media is an effective method of low calorific gas utiliz...Low-concentration methane(LCM) has been one of the biggest difficulties in using coal mine methane.And previous studies found that premixed combustion in porous media is an effective method of low calorific gas utilization. This paper studied the combustion of LCM in a divergent porous medium burner(DPMB) by using computational fluid dynamics(CFD), and investigated the effect of gas initial temperature on combustion characteristic, the distribution of temperature and pollutant at different equivalence ratios in detail. Besides, the comparison of divergent and cylindrical burners was also performed in this paper. The results show that: the peak temperature in DPMB increases as the increasing of equivalence ratio, which is also suitable for the outlet NO discharge; the linear correlation is also discovered between peak temperature and equivalence ratios; NO emission at the initial temperature of 525 K is 5.64 times,larger than NO emission at the initial temperature of 300 K. Thus, it is preferable to balance the effect of thermal efficiency and environment simultaneously when determining the optimal initial temperature range. The working parameter limits of divergent burner are wider than that of cylindrical one which contributes to reducing the influence of LCM concentration and volume fluctuation on combustion.展开更多
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 ex...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.展开更多
基金the supports by the National Basic Research Program of China (No. 2011CB201205)the National Natural Science Foundation of China (No. 51204169)+1 种基金the Research Fund for the Doctoral Program of Higher Education of China (No. 20110095120017)the Fund of China Postdoctoral Science Foundation of China (No. 20110491482)
文摘Low-concentration methane(LCM) has been one of the biggest difficulties in using coal mine methane.And previous studies found that premixed combustion in porous media is an effective method of low calorific gas utilization. This paper studied the combustion of LCM in a divergent porous medium burner(DPMB) by using computational fluid dynamics(CFD), and investigated the effect of gas initial temperature on combustion characteristic, the distribution of temperature and pollutant at different equivalence ratios in detail. Besides, the comparison of divergent and cylindrical burners was also performed in this paper. The results show that: the peak temperature in DPMB increases as the increasing of equivalence ratio, which is also suitable for the outlet NO discharge; the linear correlation is also discovered between peak temperature and equivalence ratios; NO emission at the initial temperature of 525 K is 5.64 times,larger than NO emission at the initial temperature of 300 K. Thus, it is preferable to balance the effect of thermal efficiency and environment simultaneously when determining the optimal initial temperature range. The working parameter limits of divergent burner are wider than that of cylindrical one which contributes to reducing the influence of LCM concentration and volume fluctuation on combustion.
基金The authors wish to acknowledge the support to this work by the National Key Research and Development Program of China(No.2018YFC0808500)the National Natural Science Foundation of China(No.51804237)+1 种基金the Natural Science Foundation of Hubei Province of China(No.2018CFB207)the Fundamental Research Funds for the Central Universities(WUT:2019IVB035).
文摘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.
