CH4/CO2非预混射流火焰燃烧特性实验研究

Experimental Study on Combustion Characteristics of CH4/CO2 Non-premixed Jet Flames

为了掌握含杂质生物沼气在工业燃烧装置中非预混射流火焰燃烧特性,对CH4/CO2非预混射流火焰在300 K和600 K伴流空气中的火焰形态、火焰高度以及推举高度进行了实验研究,并与CH4/N2非预混射流火焰燃烧特性进行对比.实验结果表明:在相同工况下,CH4/CO2火焰高度较低,但其推举高度高于CH4/N2火焰;两种火焰推举高度随伴流温度升高而降低.采用预混火焰模型对火焰推举高度进行了理论分析,得到了两种非预混火焰无量纲火焰推举高度与无量纲燃料流速的关联式.基于预混火焰模型的理论分析表明,预混气层流火焰速度及燃料和氧化剂密度比对非预混火焰的推举高度的影响较为显著.

To understand the combustion characteristics of non-premixed jet flames of biogas in an industrial combustor,the shape,height and liftoff height of CH4/CO2 non-premixed jet flames with co-flow air at 300 K and 600 K were studied experimentally.In addition,the combustion characteristics of CH4/N2 non-premixed jet flames were also compared.Experimental results show that under the same working condition,the flame height of CH4/CO2 flame was lower than that of CH4/N2 flame,but its liftoff height was higher.Moreover,the liftoff heights of both flames decreased with the increase in co-flow temperature.A premixed flame model was employed to analyze the liftoff height theoretically,and the relationship between the dimensionless liftoff height and dimensionless fuel velocity in these two non-premixed flames was obtained.The theoretical analysis based on the premixed flame model shows that the laminar flame velocity of premixed gas and the density ratio of fuel to air have significant effects on the liftoff height of non-premixed flame.