O_2/CO_2气氛下甲烷燃烧中NO_x转化过程的CHEMKIN模拟

The Fate of NH_3 in CH_4 Combustion under O_2/CO_2 Atmosphere with CHEMKIN Modeling

采用CHEMKIN中的PFR模型对CH4在不同气氛(O2/CO2和O2/N2)下的燃烧过程进行单程模拟来研究NH3的转化和NOx生成过程,并引入烟气再循环对其进一步模拟来研究实际富氧甲烷燃烧NOx排放机理。结果表明:富燃料燃烧时CO2气氛下的NOx排放比N2气氛高,贫燃料燃烧时2种气氛的NOx排放相当。CO2气氛下,引入烟气再循环后,过氧系数λ=0.7时,NOx排放比单程时降低95%;λ=1.2时比单程降低18%。烟气再循环是导致富氧甲烷燃烧低NOx排放的主要因素。

NH3 conversion and NOx emissions in CH4 combustion under different atmospheres （O2/CO2 and O2/N2 ） are investigated using a one-through PFR model in CHEMKIN. To further identify the low NOx emission mechanism, a PFR model with recycled flue gas is adopted. The results show that for fuel-rich condition, NH3-to-NO conversion ratio in the presence of CO2 is higher than that in N2; while for fuel-lean condition, NO emissions under these two atmospheres are at the same level. When considering the flue gas recirculation, NO emissions in the presence of CO2 are lower than that in one-through conditions by 95% for fuel-rich condition （h=0. 7） and 18% for fuel-lean condition （h=1. 2）, respectively. According to the present study, flue gas recirculation is the main reason of low NOx emission observed in oxy-methane combustion.