Oxidation Reactivity of Char Produced in a Pilot-Scale Blowpipe: Effect of the Heating Rate during Pyrolysis

In this study, oxidation reactivity of char produced in a pilot-scale blowpipe was investigated with a focus on the difference in the heating rate during pyrolysis. In addition to the blowpipe, thermogravimetry and a Curie-point pyrolyzer were employed for preparing the char sample produced at different heating rate conditions. The changes of morphological and crystalline structures as a result of the heating rate were evaluated. Both the morphological and crystalline structures of the char differed according to the heating rate during pyrolysis. For the char produced in a blowpipe, the melting of the char was observed and the specific surface area of the char drastically increased in comparison to that of the char produced in the other reactors. On the other hand, the crystalline structure of the char also developed in the rapid heating condition. According to the study results, the positive effect of the expanded specific surface area of the char was stronger than the negative effect by the ordered crystalline structure. The oxidation reactivity of the char produced in the blowpipe was much higher than those produced in lab-scale apparatuses. Therefore, the appropriate parameters obtained from the char produced in the same heating condition as the target system were necessary to predict the phenomena in the pulverized coal combustion system.