Oxy-steam气氛下低热值燃气燃烧特性研究

Study on Combustion Characteristics of LCV Gas in Oxy-steam Atmosphere

利用Fluent软件对高炉煤气在Oxy-steam气氛下的燃烧进行数值模拟,分析了水蒸气体积分数对高炉煤气燃烧温度、炉内温度分布、烟气组分体积分数、NO_(x)体积分数以及烟黑体积分数的影响。结果表明:在Oxy-steam气氛下燃烧时,由于水蒸气比热容较N_(2)更高,且存在大量的OH和H基团,高炉煤气的最高燃烧温度从1350 K下降至1290 K;与O_(2)/N_(2)气氛下的燃烧相比,在Oxy-steam气氛下燃烧时炉内温度分布更加均匀,CO燃烧更完全,炉膛出口处NOx和烟黑的体积分数均迅速减小;随着水蒸气体积分数的不断增大,炉膛出口烟气流速从0.55 m/s减小至0.505 m/s;与在O_(2)/N_(2)气氛下的燃烧相比,在Oxy-steam气氛下炉膛出口H2和CH4摩尔分数略增大。

The combustion of blast furnace gas in Oxy-steam atmosphere was numerically simulated by Fluent software,so as to analyze the effects of water vapor volume fraction on gas combustion temperature,temperature distribution in furnace,volume fraction of flue gas components,NOx volume fraction and soot volume fraction.Results show that when burning in Oxy-steam atmosphere,the maximum combustion temperature of blast furnace gas decreases from 1350 K to 1290 K due to the fact that specific heat capacity of water vapor is higher than that of N2 and there exists a large number of OH and H functional groups.Compared with the combustion in O_(2)/N_(2) atmosphere,temperature distribution in the furnace is more uniform and CO combustion is more complete in Oxy-steam atmosphere,furthermore,NOx volume fraction and soot volume fraction at the furnace outlet decrease rapidly.With the increase of steam volume fraction,the flue gas velocity at the furnace outlet decreases from 0.55 m/s to 0.505 m/s.Compared with the combustion in O2/N2 atmosphere,the mole fraction of H_(2) and CH_(4) at the furnace outlet increases slightly in Oxy-steam atmosphere.