煤粉预热燃烧特性及动力学分析

实验利用热重天平,采用非等温燃烧方法研究了国内某炼铁厂高炉喷吹的典型煤粉预热后燃烧特性及反应动力学参数。考察了煤粉在423,473,523,573,623,673,723,773K温度等级下,煤粉试样的燃点、燃烧峰值温度、结束温度、综合燃烧特性指数(G)、燃烧峰值速率等动力学特征参数,计算了煤粉燃烧过程的活化能(E)和指前因子(A)。分析结果表明,北区煤粉在423~773K不同温度等级燃烧过程中,着火点温度最多下降了240K,失重峰温度最多提前了263K,最大燃烧速率最大幅度提升了1.29倍,燃烧特性指数最大为29.8倍;从动力学角度分析出两段热解活化能和指前因子之间均存在良好的线性拟合关系,煤粉燃烧为一级反应;煤粉有明显预热效果温度应不低于673K。

Combustion characteristics and kinetic analysis ofpreheating pulverized coal

Experimental research on non-isothermal combustion characteristics and dynamics parameters of applied pulverized coal under preheating domestically is conducted with a thermo gravimetric balance. The combustion characteristic parameters such as ignition temperature, peak temperature at maximum weight loss rate, burnout temperature, general burn exponent(G), and maximum combustion rate are studied under different preheating temperatures of 423, 473, 523, 573, 623, 673, 723 and 773 K. The activation energy (E) and frequency factor (A) are also calculated. The results show that for pulverized coal in the North Area, during the preheating process, when temperature varies from 423 K to 773 K, ignition temperature decreases by 240 K mostly, peak temperature at maximum weight loss rate decreases by 263 K at most, maximum weight loss rate increases as 1.29 times, and G increases up to 29.8 times. It shows that there is lining fit result between E and ln A, which proves that the reaction could be regarded as first order reaction. The combustion process behaves greatly when preheating temperature is over 673 K for the pulverized coal.