CO 2 and H 2O Gasification Kinetics of a Coal Char in the Presence of Methane

Abstract

The kinetics Of CO2 and H2O gasification of a Chinese coal char in the presence of methane has been studied using a thermogravimetric analyzer (TGA) in the temperature range from 1173 to 1273 K. It was observed that the rate of carbon conversion increased with an increasing temperature and decreased with an increasing CH4 concentration. The rate of carbon conversion during the gasification of the char experienced a maximum without the presence of methane but decreased continuously with carbon conversion in the presence of methane. Carbon deposition from CH4 cracking reduced the overall rate of carbon conversion during gasification, but this effect was reduced as the temperature and concentration Of CO2 or H2O were increased. A gas-solid reaction shrinking core model was developed and applied to the char-CH4-CO2/H2O systems. The experimental results were used to determine the kinetic parameters. The model predictions compared favorably to the measured data. The overall carbon conversion rate has been shown to be a combination of carbon gasification, by CO2 or H2O, respectively, and methane cracking.