摘要
以分形几何为理论工具 ,采用低温氮气吸附法 ,对四种煤在低温燃烧过程中表面形态变化作了考察。通过对原煤及燃烧过程中煤焦表面分维的测定 ,结合实验中所测得的比表面积 ,分析得到了煤燃烧过程中表面结构的变化历程 ,揭示出此种气固多相反应具有分形动力学的行为特征。
Using fractal theory as a theoretical tool, the changes of surface morphology of coal chars of four types of coal during low temperature combustion were studied by nitrogen adsorption. Through determining the fractal dimension of surfaces of chars as well as coals in combination with the measured specific surface areas, the course of surface structure alteration during coal combustion could be properly characterized. During coal combustion the fractal dimension of surfaces of coal chars increased faster than their specific surface areas, reaching almost 3 at even initial stage of the reaction. From the comparison of the fractal dimension of chars with their corresponding value of original coals which was much smaller, it could be seen that the coal combustion took place in a three dimensional network surface structure of coal chars so that the reaction had a fractal kinetic behavior. The increase of the fractal dimension of char of higher rank coal during coal combustion was higher than that of char of lower rank coal. The increase of the specific surface area behaved oppositely, implicating that there was no one to one corresponding relationship between the specific surface area and the fractal dimension of coal chars. The variations of the fractal dimension of coal chars showed the similar tendencies at the combustion temperatures of 550℃, 600℃ and 650℃, as well as their specific surface areas, which provided the evidence of the definite kinetic course of coal combustion at low temperature range.
出处
《燃料化学学报》
EI
CAS
CSCD
北大核心
2001年第1期24-28,共5页
Journal of Fuel Chemistry and Technology
基金
山西省归国留学人员基金! (95 16 )&&
