全氧煤粉低氧浓度燃烧动力学参数的热重实验

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Coats Redfern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.

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

Combustion characteristics and kinetic parameters of four regional coal samples in O2/CO2 atmosphere were investigated using thermogravimetry(TG). The experiments were performed in low O2 volume fraction varying from 7.5% to 20% at a heating rate of 20 0C?min-1 .With Arrhenius and Coats-Redfern equations, the kinetic parameters under different O2 volume fraction were calculated through 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 compensate 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 reduce of O2 volume fraction, the reaction rate constant rises more and more gently by the temperature increasing.