Kinetics of coke gasification with H2O-O2-Ar and CO2-Ar gas mixture at high temperature

Abstract

In order to apply the hydrogen contained gas injection into tuyere in the blast furnace, it is necessary to investigate the coke gasification reaction when various gases containing hydrogen and oxygen are injected. The coke gasification experiments were carried out with various concentration of H2O-O2-Ar mixture gas in the temperature range 1473K-1773K by using TGA, QMS and optical pyrometer. In this condition, the rate controlling step might be gas phase diffusion by the comparison between mass transfer rate and apparent reaction rate although some results contradict it. In addition, some experiments were carried out with the change of concentration of H2O and O2 at 1773K to find the apparent reaction rate and investigate the possibility of heat compensation. Apparent reaction rate has low O2 concentration dependency and has the linear relationship with H2O concentration. Finally, the difference of coke porosity change was investigated by injecting different gases: CO2 and H2O. Because CO2 has low reactivity, it diffuses into the coke pores and then, reacts with coke there. It leads to increase the growth rate of coke porosity and decrease the reduction rate of particle size. On the contrary to this, injection of H2O leads to decrease the growth rate of coke porosity and increase the reduction rate of particle size.