高温低氧气氛下煤粉燃烧特性

Investigation on Combustion Characteristics of Pulverized Coal in High-temperature Low-oxygen Atmosphere

利用自制恒温热重实验系统,研究了模拟炉膛烟气环境(即高温低氧气氛)下煤粉的燃烧特性.结果表明:煤粉突然置于高温环境中,失重曲线存在一个转折,随着煤化程度降低,这一现象更加明显;煤粉在1 500℃下燃烧剧烈,900℃下的燃尽时间约为1 500℃下的6倍,1 300℃以上时温度对燃烧反应初期的燃烧特性影响较小;1 300℃相对于800℃,氧气体积分数升高幅度相同时燃烧失重速率增大幅度减小;当水蒸气体积分数达到10%时,其对燃烧反应初期挥发分析出燃烧的促进作用较为明显;当气氛中CO2体积分数升高到15%后,继续升高CO2体积分数,燃烧失重速率减小.

Combustion characteristics of pulverized coal were studied on self-made bench which could a- chieve thermal gravimetric measurement at constant temperatures in simulated furnace flue gas atmosphere （i. e. high-temperature low-oxygen atmosphere）. Results show that in the constant temperature environment, the weight loss curve of pulverized coal has a turning point, and with the decrease of coal rank, this phenomenon becomes more obvious. The pulverized coal burns strongly at 1 500 ℃, and the burnout time at 900 ℃ is 6 times of that at 1 500 ℃ ～ temperature has little influence on the early stage of combustion above 1 300 ℃. For the same rise rate of oxygen concentration, the increasing degree of weight loss rate at 1 300 ℃ is smaller than at 800 ℃. The effect of water vapor volume fraction on the promotion of coal devolatilization and combustion would be more obvious in the early stage of combustion when the water vapor volume fraction gets up to 10%. The weight loss rate would be reduced if the volume fraction of CO2 is kept to be raised after having got up to 15%.