两相流中煤粉的燃烧机理及动力学特征

Mechanism and kinetic characteristics of pulverized coal combustion in two phase flow

利用微型流化床动力学分析仪研究了两相流条件下无烟煤粉的燃烧反应机理和动力学特征,并与热重法所得结果进行比较分析。结果表明,当温度大于850℃时,煤粉燃烧机理发生了变化,燃烧气态产物的生成比例也随之改变;当气速大于0.10 m/s时,气体扩散限制基本被消除,煤粉燃烧反应速率主要受界面化学反应控制;煤粉燃烧反应速率随着氧气分压的增大呈幂函数形式增长,且氧气分压对煤粉静置燃烧的影响更加显著。煤氧两相流燃烧的表观活化能与静置燃烧相比降低了49 kJ/mol,相同温度条件下两相流燃烧的界面化学反应阻力也明显小于热重法测试结果。

The combustion reaction mechanism and kinetic characteristics of pulverized anthracite coal in two phase flow were studied by micro fluidized bed kinetic analyzer, and compared with those by thermogravimetry method. The results show that the combustion reaction mechanism of pulverized coal and the composition of combustion gas product change when the temperature exceeds 850 ℃. When the flow rate exceeds 0.10 m/s, the effect of gas diffusion is eliminated basically, and the combustion reaction rate of pulverized coal is mainly controlled by the interface reaction. The combustion reaction rate of pulverized coal increases in a power function form with oxygen partial pressure, and the influence of oxygen partial pressure on the static combustion is more remarkable. The apparent activation energy of pulverized coal combustion in two phase flow decreases by 49 kJ/mol compared with that of static combustion, and the interfacial chemical reaction resistance of pulverized coal combustion in two phase flow is also much smaller than the results by thermogravimetry method at the same temperature.