氧体积分数对煤炭自燃诱导过程影响的试验研究

Effects of Oxygen Volume Fraction on Induction of Coal Spontaneous Combustion

利用热天平缓慢升温法及化学动力学理论研究氧体积分数对蒙混煤低温氧化反应不同阶段的作用效果及活化能的变迁特性,并从反应能垒角度研究氧体积分数对煤炭自燃影响的内在原因.结果表明:失水失重阶段受氧体积分数的影响较小;在氧体积分数为5%~15%时氧化反应阶段和着火燃烧阶段对其变化不敏感,当氧体积分数从15%增大到20%时反应活性增强;5%氧体积分数下着火燃烧阶段的最大反应速率和燃烧放热量分别约为20%氧体积分数下的11%和60%;氧化反应初期5%、10%和15%氧体积分数下的反应活化能分别为20%氧体积分数下的2.40倍、2.11倍和1.56倍;当氧体积分数为15%~20%时,煤样氧化反应的活化能随反应的进行持续减小,其自燃过程具有氧化自加速性;当氧体积分数为5%~10%时,氧化反应末期的活化能大于氧化反应中期,氧化反应受到抑制.

To analyze the internal mechanism of coal spontaneous combustion influenced by oxygen volume fraction from the point of view of reaction energy barrier,experimental tests were carried out to study the effects of oxygen volume fraction on the low-temperature oxidation of Menghun coal at different reaction stages,and to study the transition characteristics of active energy in spontaneous combustion process according to chemical dynamic theory by slow pyrolysis using thermobalance.Results show that the oxygen volume fraction affects little in dewatering and weight loss process.Both the oxidation process and combustion process change little for the oxygen volume fraction varying from 5%to 15%,and the reactivity enhances rapidly when the oxygen volume fraction increasing from 15%to 20%.The maximum reaction rate and heat output under the oxygen volume fraction of 5%are respectively 11%and 60%of that under the oxygen volume fraction of 20%.In initial oxidation stage,the active energy under oxygen volume fractions of 5%,10%and 15%is respectively 2.40,2.11and 1.56times of that under the oxygen volume fraction of 20%.The spontaneous combustion has self-acceleration quality when the oxygen volume fraction is in 15%-20%,with the continuous reduction of active energy in oxidation process.When the oxygen volume fraction varies from 5%to 10%,the coal oxidation will be inhibited due to higher active energy infinal oxidation stage than in middle oxidation stage.