粒度对煤粒燃烧和热解影响的理论分析

THEORETIC ANALYSIS OF EFFECTS OF PARTICLES SIZES ON COMBUSTION AND PYROLYSIS OF COAL

在化学热力学和动力学理论中引入表面项,并由此来分析和讨论粒度对煤颗粒燃烧和热解反应的影响规律.研究结果表明,煤颗粒的粒度对其燃烧和热解反应的热力学性质和动力学参数有明显的影响,粒度越小,影响越大;减小煤颗粒的粒径,化学反应的吉布斯函数差减小,煤颗粒燃烧和热解的趋势增大,使着火温度和热解温度降低,自燃容易发生;并且减小煤颗粒的粒径,其摩尔表面能增大,导致其燃烧和热解的表观活化能降低和速率常数增大,使煤颗粒的燃烧和热解速率加快,使转化率、燃尽度和热解度增加.

The surface terms are induced in chemical thermodynamics and kinetics, and effects of particle sizes on combustion and pyrolysis of coal particles are analysed and discussed. The results show that the particle size has obvious effects on combustion and pyrolysis of coal particles in thermodynamic properties and kinetic parameters, when particle size smaller, the effects becomes larger; with the particle size decreasing, the difference of Gibbs function decreases, the tendencies of burning and pyrolysis increase, the burning point and pyrolytic temperature decrease, the spontaneous ignition occures easily,as well as the molal surface energy increases when the particle size decreasing, so as to the apparent activation energies of burning and pyrolysis decrease andthe rate constant increases. Consequently, the burning and the pyrolytic rates of coal particles accelerate, and the conversion rate, the combustion and the pyrolysis effectivenesses of coal particles increase.