Unification of Gasification Kinetics of Char in CO2 at Elevated Temperatures with a Modified Random Pore Model

Abstract

The gasification of a char has, so far, been mainly studied at low temperatures and low heating rates, using thermogravimetric analysis. Studies on the gasification of a char in CO2 at elevated temperatures and high heating rates are necessary to develop integrated coal gasification combined-cycle (IGCC) technology. Coal gasification is a very complicated phenomenon, which makes a generalized understanding and description of gasification reactivity of a char very important. Using a unique fluidized bed, the reactivity of a char pyrolyzed at elevated temperatures and high heating rates was investigated. A generalized expression of the gasification reactivity of a char under various conditions was approached with a modified random pore model proposed in this work. It was clarified that a shrinking core model was not appropriate to describe char gasification in CO2. On the basis of our results and those in the literature, it was identified that the char reactivity could be unified with a master curve not onl...