褐煤在N2及CO2气氛下的热解与富氧燃烧特性

Lignite pyrolysis and oxy-fuel combustion characteristics under N2 and CO2 atmospheres

为了掌握不同气氛下褐煤热解与富氧燃烧的特性以及其之间的联系,在管式炉反应器上利用锡盟褐煤在N2和CO2气氛以及600~1000℃条件下进行热解.进一步对其在O2/N2以及O2/CO2气氛下进行富氧燃烧实验,考察不同反应温度(600~1000℃)以及不同氧气体积分数(21%~60%)条件下的富氧燃烧特性,结合热解实验结果探究CO2气化反应对富氧燃烧的影响.结果表明,CO2气氛中锡盟褐煤在700℃时开始CO2气化反应,随温度增加气化反应增强,CO2主要通过高温区的气化反应来影响煤热解及燃烧,700℃以上气化反应能促进富氧燃烧进程.对于O2/CO2气氛的富氧燃烧,当氧气体积分数为30%时,在800℃以下温度对CO氧化反应影响更大,而在800℃以上温度对CO2气化反应影响更大.当氧气体积分数相同时,O2/N2以及O2/CO2气氛下褐煤富氧燃烧反应时间差异不大.

A pyrolysis experiment was carried out in a tubular furnace using Ximeng lignite under N2 and CO2 atmospheres at the temperature between 600℃ and 1000℃,in order to investigate the characteristics of lignite pyrolysis and oxy-fuel combustion under different atmospheres and to obtain their relationship.Further oxy-lignite combustion experiments under O2/N2 and O2/CO2 atmospheres were performed to investigate the oxy-lignite combustion characteristics under different reaction temperatures(from 600℃ to 1000℃)and different oxygen concentrations(from 21%to 60%).The effects of CO2 gasification on oxy-fuel combustion were explored based on the results of lignite pyrolysis.Results show that the Ximeng lignite gasification starts at 700℃ under CO2 atmosphere and the CO2 gasification is enhanced with the increase of temperature.CO2 mainly affects coal pyrolysis and combustion through gasification reaction at high temperature;the presence of gasification reaction after 700℃ can promote the oxy-fuel combustion process.For oxy-fuel combustion under O2/CO2 atmosphere,when the oxygen concentration is 30%,the temperature below 800℃ has greater effect on CO oxidation,while the temperature above 800℃ has greater effect on CO2 gasification.Moreover,there is little difference in the combustion time between two atmospheres of O2/CO2 and O2/N2 with the same oxygen concentration.