空气和O_2/CO_2气氛下煤粉着火特性试验研究

Experimental study of pulverized coal ignition characteristics under air and O_2/CO_2 combustion

利用金属网反应器研究了大同烟煤在空气气氛和O2/CO2气氛不同氧气体积分数下的着火特性,并利用热重分析仪分析了2种气氛下煤焦的反应性.试验发现:在相同氧气体积分数下,O2/CO2气氛的煤粉着火温度较O2/N2气氛的高,O2/CO2(φO2=21%,φCO2=79%)气氛下大同烟煤着火温度较空气气氛提高了35.7℃,在O2/CO2气氛下出现着火延迟;在O2/CO2气氛下φO2=30%时,大同烟煤与空气气氛具有比较接近的着火温度;在N2和CO2气氛下制得的煤焦,在相同氧气体积分数2种气氛下的表观活化能差异明显,煤焦反应性是影响煤粉着火温度在O2/CO2气氛下出现延迟的重要原因.

Wire-mesh reactor was used to study the Datong bituminous coal ignition characteristics in air and O2/CO2 atmosphere.The reaction kinetics of char samples under O2/N2 and O2/CO2 atmosphere were investigated by utilizing the thermal gravimetric analysis.An increase in the average particle ignition temperature is observed for the coal when air（φO2=21%,φN2=79%） is replaced with a mixture of O2/CO2（φO2=21%,φCO2=79%）,and the ignition temperature increase 35.7 ℃.When the oxygen concentration increases to 30% under O2/CO2 atmosphere,the Datong pulverized coal ignition temperature is very close to the temperature under air atmosphere.Under O2/CO2 atmosphere,the pulverized coal apparent activation energy is higher than the activation energy under O2/N2 conditions with the same oxygen concentration.In particular,the char reactivity is largely responsible for the observed difference in particle ignition temperature in air and in O2/CO2.