不同粒径褐煤的热解特性及煤焦结构

Pyrolysis Characteristic and Char Structures of Lignite with Different Particle Sizes

以内蒙褐煤为研究对象,于固定床反应器上,考察了粒径对褐煤热解过程中的产气率以及各气体组分含量的影响,通过XRD以及物理吸附等手段研究了热解后各煤焦的微观结构特性,并采用热天平探讨了不同粒径煤焦水蒸气气化反应活性的差异.研究表明,当原煤粒径增大,原煤热解产气率有所下降;对于各组分,CO,H_2,CH_4含量均随原煤粒径增大而减小,但CO_2呈相反趋势.对于粒径越大的原煤,由于挥发分脱除不够完全,生成的煤焦碳化程度较低,使得煤焦石墨化程度越低,比表面积也越小;另外,不同粒径煤焦的水蒸气气化反应活性随着粒径的增大而明显降低.

The effects of particle size on gas yields and gaseous compound contents were investigated by Inner Mongolia lignite pyrolysis tests performed in fixed-bed reactor. The structural characteristics of chars were determined by methods of XRD and physical adsorption. Reactivities of chars of different particle sizes with steam were studied by a thermogravimetric analyzer. The results show that the pyrolysis gas yield decreases as the particle size increases. For gaseous compound contents, the content of CO2 increases with particle size, but contents of CO, H2, CH4 show opposite trends. The degree of graphitization and the specific surface area of the char with relatively large particle size are relatively low, due to the incomplete devolatilization of the char. In addition, the reactivity of char gasification with steam decreases as the particle size increases.