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对气化过程中3种不同变质程度煤的焦炭表面孔隙结构的发展变化规律及其表面分形特征进行研究,发现气化过程不同变质程度煤的焦炭的吸附特性曲线一般均属于典型的I类吸附等温线,表征了煤焦表面主要为微孔的吸附特征;随着气化反应的深入,微孔逐渐生长扩大,焦炭的吸附等温线出现了由I类向II类吸附等温线变化的趋势;同时,煤焦表面的孔径为2~10nm内的中孔随着气化反应的进行变化比较明显,且此范围内的变化与煤的变质程度密切相关,而孔径为10~200nm的中孔和部分大孔则基本保持不变。利用吸附法计算煤焦表面的分形维数,发现煤焦表面存在2个不同的分形维数D1和D2,分别表征了不同的孔径范围的表面分形特征,且D1和D2与煤焦比表面积和微孔比表面积有一定的关联性,但是其变化一般超前于比表面积和微孔比表面积的变化。
The development and variation regularity of surface pore structure and surface fractal characteristics of coke with three different metamorphic degrees of coal during gasification process were studied. It was found that the adsorption characteristic curves of coke with different metamorphic degrees of coal gasification generally belonged to typical class I adsorption The adsorption isotherms of coal char surface were mainly characterized by micropores. With the further gasification reaction, the micropores gradually grew and expanded, and the adsorption isotherms of coke tended to change from type I to type II adsorption isotherms. At the same time, the mesopore with the pore size of 2 ~ 10nm on the surface of coal char changes more obviously with the gasification reaction, and the change in this range is closely related to the degree of coal metamorphism, while the mesopores with pore size of 10 ~ 200nm Part of the big hole is basically unchanged. Calculating the fractal dimension of coal char by adsorption method, we find that there are two different fractal dimensions of coal char surface, D1 and D2, which characterize the surface fractal characteristics of different pore sizes respectively. And the ratio of D1 and D2 to coal char surface area and Micropore specific surface area has a certain relevance, but its change generally ahead of the specific surface area and micropore specific surface area changes.