Behaviors and kinetics of non-isothermal gasification reaction of cokes with different reactivity

Abstract

Due to the great difference of coke properties used in blast furnaces, how to reasonably evaluate coke has become a hotspot. In this study, the non-isothermal gasification behaviors and kinetics of cokes with different reactivity are studied, which provides theoretical basis for reasonable coke evaluation. The coke reactivity index of coke A, B and C are 24.75%, 30.80% and 41.25%, respectively. The FWO method is used to calculate the kinetic parameters. The results show that coke reactivity has little influence on gasification reaction starting temperature at lower heating rate. The starting temperature decrease gradually with coke reactivity at higher heating rate. Under the same conditions, the alkali index and microcrystalline structure of cokes can better characterize the coke reactivity. The gasification mechanism does not change with coke reactivity. The reaction is divided into two stages. In the early stage, the average apparent activation energy E of coke powder A, B and C are 211.52 kJ/mol, 214.96 kJ/mol 208.99 kJ/mol, respectively. The optimal mechanism models are all F model, in which the integral form is G(α) = (1–α)−1–1. In the later stage, the average E of coke powder A, B and C are 226.89 kJ/mol, 207.53 kJ/mol and 192.12 kJ/mol, respectively. The optimal models are all A1 model, in which the integral form is G(α) = –ln(1–α).