Gasification Reactivity And Combustion Characteristics Of Chars From Coal Pyrolysis

China is one of the main countries in coal consumption in the world, and most coal is used for direct combustion. The single utilization approach of coal resource results in low utilization efficiency of coal resource, environmental pollution and so on. Therefore, it is very significant to implement coal staged conversion and clean coal technology from the perspective of the sustainable development of resources and environmental protection. Pyrolysis, as one of the effective ways for coal staged conversion, can produce gas, tar, and a lot of char. This paper is aimed to investigate the gasification reactivity and combustion characteristic of the char from the integrated process of CO₂ reforming of methane with coal pyrolysis.The pyrolysis chars of Buliangou subbituminous coal were prepared in a fix-bed reactor, and the gasification reactivity and combustion characteristics of the resultant char were carried out in a thermogravimetric analyzer. The effect of pyrolysis conditions ?pyrolysis temperature, pyrolysis holding time and pyrolysis atmosphere?, inherent mineral in char and gasification temperature on gasification reactivity was explored. The results showed that the pyrolysis conditions had an important influence on the gasification reactivity. With increasing the pyrolysis temperature from 450 ? to 750 ?, the resultant char exhibited the decreasing gasification reactivity. The gasification reactivity of chars decreased with long pyrolysis holding time. Pyrolysis atmosphere had little influence on gasification reactivity. In comparison, the gasification reactivity of chars prepared from hydropyrolysis and integrated coal pyrolysis with CO₂ reforming of methane was slight higher than that of chars prepared from pyrolysis under N₂ atmosphere.The effect of the inherent mineral in coal on the char gasification reactivity was examined by washing the raw coal with HCl and HF to remove most of the inherent mineral. The results found the gasification reactivity of char prepared from raw coal was higher than that from the de-ashing coal, which is related with catalytic effect of the alkali and alkaline-earth metals in inherent mineral in coal/char gasification. The char reactivity increases dramatically with the increase of gasification temperature in 800-900 ?.The effect of pyrolysis conditions ?pyrolysis temperature, pyrolysis holding time and pyrolysis atmosphere? and combustion heating rate on combustion characteristic of chars was also investigated, and Coats-Redfern integrate method was used to kinetic analysis of char combustion. The results showed that pyrolysis temperature obviously influenced the combustion of char prepared by the integrated process of CO₂ reforming of methane with coal pyrolysis. The combustion performance of char decreased and activation energy gradually increased with the pyrolysis temperature, which was positively related with low volatile in the char. Pyrolysis holding time and atmosphere has slight effect on the char combustion. The char from hydropyrolysis and integrated process showed the similar combustion behaviors and activation energy as that obtained under N₂ atmosphere. The heating rate of combustion affects the char combustion characteristics. High heating rate results in the combustion at high temperature.