Effect of temperature on reaction and degradation behaviors during CO₂ and H₂O gasification reactions of coke in same conversion ratio

Abstract

The efficiency of blast furnaces is adversely affected by coke degradation via gasification. Considering the utilization of hydrogen-enriched blast furnaces, it is essential to investigate the reaction and degradation behaviors of coke at different temperatures. In this study, coke gasification experiments were conducted under CO₂ and H₂O atmospheres at different temperatures to prepare cokes with a conversion ratio of 0.2. The reaction rate of the H₂O gasification reaction was higher than that of the CO₂ gasification reaction at the same temperature. The activation energies for CO₂ and H₂O gasification were 150.2 and 126.0 kJ/mol, respectively. After gasification, the shrinkage ratio was low by H₂O gasification at 1273 K and increased with increasing temperature, indicating that the surface reaction became the control factor that consumed the coke matrix with increasing temperature. On the other hand, the shrinkage ratio by CO₂ gasification tended to be stable from 1273 to 1673 K. Furthermore, the increase in the porosity of coke by H₂O gasification was lower than that by CO₂ gasification at higher temperatures. In addition, the strength of the coke via H₂O gasification was higher than that of the coke via CO₂ gasification.