全氧煤粉低氧浓度燃烧动力学参数的热重实验

Kinetic Parameters of Oxy coal Combustion in Low Oxygen Concentration with Thermogravimetry

摘要:

利用热重分析仪研究了四种煤粉在低氧惰性气氛（即O2/CO2）下的着火特性、燃尽特性.实验在O2体积分数为7.5%~20%，升温速率20 ℃·min-1条件下进行.通过对Arrhenius和CoatsRedfern方程进行最小二乘法的二元一次线性回归,求得煤粉在不同低氧浓度下的动力学参数.结果表明：随着O2体积分数降低，着火温度基本不变，燃尽温度增大；活化能、指前因子和反应级数都随着O2体积分数降低而不同程度地减小；活化能和指前因子之间存在补偿效应，计算可得等动力学温度和反应速率常数;当O2体积分数小于12.5%，随O2体积分数减小，煤粉的反应速率常数随反应温度增大而增大的趋势越来越平缓.

Abstract:

Combustion characteristics and kinetic parameters of four regional coal samples in O2/CO2 atmosphere were investigated by thermogravimetry(TG). The experiments were performed on low O2 volume fraction varying from 7.5% to 20% at a heating rate of 20 ℃·min-1. With Arrhenius and Coats Redfern equations, the kinetic parameters under different O2 volume fractions were calculated with the method of least squares linear regression. The results show that ignition temperature keeps constant and burn out temperature rises in lower O2 volume fraction. Activated energy, pre exponential factor and reaction degree all decrease in varying extent with the lower O2 volume fraction. There was compensation effect between activation energy and pre exponential factor, besides, the isokinetic temperature and reaction rate constant of four coal samples were obtained. When O2 volume fraction is lower than 12.5%, with reduction of O2 volume fraction, the reaction rate constant rises more and more mildly with the increasing of the temperature.