在三个升温速率下用热天平研究煤的热解及其反应动力学

THERMOGRAVIMETRY STUDY ON PYROLYSIS AND PYROLYTIC REACTION KINETICS OF COAL WITH THREE HEATING RATES

利用三个升温速率热重分析法在氮气气氛下研究了八个煤样的热解反应动力学。结果表明,随热解程度加深,活化能呈下降趋势,而补偿因子k却随热解程度加深呈上升趋势。此值与转化率α有着较好的线性关系。另外,在本文中提出一个积分程序分解温度参数T_(ipdt)用以表征煤的反应活性,T_(ipdt)越低,反应活性越好。它与C_(daf)的关联式为:T_(ipdt)=1097·C_(daf)%-141.90(r=0.953)

The pyrolysis and pyrolytic reaction kinetics of eight samples including three raw coals and five residues of coal extraction, all mineral matter free, were investigated with three heating rates, 2. 5, 5, 10℃/min, in a niitrogen atmosphere by means of thermogravimetry. In terms of the view that there are various products in coal pyrolytic process, we used the equation: logΦ=log (AE/(R(1-a)))-2.315 -0. 4567(E/RT) to process the experimental data. We found that the apparent activation energy of the pyrolytic reaction decreased.as conversion increased, while the compensation factor, k=αE/(logA), increased as conversion increased. The κ value shows a good linear relationship with conversion α. An index, integrate programmed decomposition temperature, T_(ipdt), was proposed to characterize coal pyrolytic reaction activity. It has a linear relationship with C_(dnf%), that is T_(ipdt)=1097.0 C_(daf)%-141.9 (r=0. 953). The reaction activity increases as the value T_(ipdt), decreases. Moreover, we can utilize the two relationships: k=a^1α+b^1 and E=aα +b^1, to predict the kinetic parameters of coal pyrolytic reaction at certain conversion α.