Kinetic Modeling of CO₂ and H₂O Gasification Reactions for Metallurgical Coke Using a Distributed Activation Energy...

A distributed activation energy model (DAEM) was applied to the kinetic analysis of CO₂ and H₂O gasification reactions for pulverized metallurgical coke. The results of the scanning electron microscopy observations and CO₂ gas adsorption suggested that the gasification reaction occurs at the particle surface. Therefore, a grain model was employed as a gasification reaction model. The reaction rates of CO₂ and H₂O gasification were evaluated based on the DAEM. The activation energy changed as the reaction progressed and hardly depended on the particle size. The activation energies were 200-260 kJ/mol in CO₂ gasification and 220-290 kJ/mol in H₂O gasification. The frequency factor of H₂O gasification was approximately 10 times larger than that of CO₂ gasification, regardless of the progress of the reaction. At the same activation energy level, the frequency factor showed a higher value with a decrease in the particle size. This result was consistent with the theory of the grain model and indicated that the gasification reaction of the pulverized coke with a micrometer scale occurs on the surface of the coke particle. Furthermore, the value predicted by the DAEM was in good agreement with the experimental one.