Gasification and kinetic study on metallurgical cokes in CO2-N2-H2O and CO2-N2 atmosphere

A high-temperature gas-solid reaction device was used to simulate the gasification of coke in a hydrogen-rich blast furnace, with the gasification reaction of water/anhydrous bulk cokes studied. CO2 and H2O effects on coke gasification kinetics were analyzed in CO2-N-2-H2O and CO2-N-2 with the experimental temperature of 1173-1523 K, the CO2 content of 15-60%, and the H2O content of 15%. Compared with those of CO2-N-2, the gasification reaction rate and carbon conversion rate of cokes in the CO2-N-2-H2O mixture were significantly higher. Carbon conversion rates of the CO2-N-2-H2O mixture at different temperatures were about 30% higher than those of CO2-N-2 on average, and the gasification reaction rate was about 50% higher on average. There were two temperature regions for gasifying cokes in CO2-N-2-H2O and CO2-N-2 mixtures. At 1,273 K, the gasification reaction is transformed into diffusion control, which is from chemical reaction control. The aggravation of coke gasification by H2O generated after hydrogen reduction of iron ores was mainly reflected at the lower temperature. Besides, the kinetic model analysis showed that random pore model was optimal in describing the gasification reaction of cokes in CO2-N-2-H2O and CO2-N-2, and the addition of H2O improved the gasification reaction's activation energy.