Gasification Reactivity and Kinetic Model of High-ash Coal Char

CO2gasification experiments of Hexi coal char were carried out, and carbon crystalline structure of the coal char was analyzed.The results indicate that the graphitization degree of char samples is in the order of demineralized coal char(DC)clean coal char(CC) raw coal char(RC)tailing coal char(TC) under the same coke making conditions, and the gasification activity of char samples in the order of TCRCCC correspondingly, showing that the existence of ash inhibits the char graphitization and enhances the gasification reactivity of coal char to some extent. High-ash coal char(ash≥48.47%) exhibits higher gasification reactivity in the initial stage, and the gasification reactivity index(Rs) of coal char is Rs(TC)=1.304Rs(RC)=2.421Rs(CC). In the later stage, the gasification reactivity of high-ash coal char decreases gradually with the increase of ash layer resistance. CO2gasification reaction of high-ash coal char can be well described by 3-D diffusion model. However, the best kinetic model expressing the reactivity of low-ash coal char is shrinking core model with chemical reaction controlling.