煤粉高掺钙燃烧时煤灰矿物的形成动力学机理与实验研究

KINETIC ANALYSIS AND EXPERIMENTAL STUDY ON FORMATION MECHANISM OF COAL ASH MINERALS AT HIGH CALCIUM CONTENT IN PCC BOILERS

在前期研究工作的基础上,通过实验研究和动力学分析,对煤粉炉中煤粉在高掺钙条件下燃烧时的煤灰矿物形成机理作了进一步阐释。实验证明,在高掺钙条件下,煤灰中的主要矿物确实是硅酸二钙和钙铝黄长石,而且在掺钙数量足够时以硅酸二钙为主。动力学分析的结果则说明,在煤粉炉的燃烧条件下,形成硅酸二钙等矿物的固相反应速度相当高,可以在几秒钟内完成大部分反应。了解煤粉高掺钙条件下燃烧时的煤灰矿物形成机理,可以为粉煤灰改性处理的研究提供理论指导。

On the basis of thermodynamic analysis in the former study, further explanation is given for the formation mechanism of coal ash minerals on condition that much calcium oxide is added to the coal in the PCC（pulverized coal combustion） boilers by means of experimental study and kinetic analysis. According to the experiments, at high calcium content, the main mineral phases in coal ash are really Dicalcium Silicate （2CaO·SiO2） and Gehlenite （2CaO·AhO3·SiO2）, and mostly 2CaO·SiO2 when calcium is enough. The kinetic analysis shows that, during combustion in PCC boilers, the rate of solid phase reaction to form 2CaO·SiO2 is very fast and that most reactions can be finished within several seconds. The knowledge of coal ash formation mechanism at high calcium content may provide theoretical instructions for the study on fly ash improvement.