DAEM和Coats-Redfern积分法研究煤半焦燃烧动力学的比较

COMPARISON BETWEEN DAEM AND COATS-REDFERN METHOD FOR COMBUSTION KINETICS OF COAL CHAR

利用恒温和程序升温热重技术研究了神木煤半焦的燃烧动力学 ,采用DAEM (分布活化能模型 )和Coats Redfern积分法对其进行了动力学分析 ,比较了二者在处理程序升温半焦燃烧反应动力学的差异 ,同时还对恒温及程序升温的燃烧动力学进行了分析 .结果表明 ,在恒温燃烧和程序升温燃烧过程中 ,随着燃烧反应的进行 ,比燃烧速率逐渐增加 ,所得半焦燃烧的活化能有不同的变化趋势 .DAEM和Coats Redfern积分法因所用方法的不同而使结果有所差异 .而恒温燃烧时由于所用燃烧温度较低 ,可以最大限度地消除外扩散的影响 ,使所得动力学参数更接近半焦燃烧的本征动力学参数 .

The combustion kinetics of Shenmu char, prepared at 900°C in Ar atmosphere for 30 min, was systematically investigated by using isothermal and temperature-programmed TG technique. The combustion kinetics was analyzed using the DAEM (distributed activation energy model) and the Coats-Redfern integration method. The difference of these two methods was compared. The results indicated that during isothermal combustion and temperature programmed combustion process, with increasing combustion conversion, the specific combustion rate increased and the combustion activation energy showed different changes. DAEM and Coats-Redfern placed the emphasis on different aspects of combustion and obtained different results. The isothermal TG technology at a lower temperature could reduce the external diffusion effect during combustion as much as possible. Therefore, the kinetic results calculated from isothermal TG technology were close to the intrinsic values.