Reaction kinetics of char—CO2 gasification

Reaction kinetics of char-CO2 gasification at atmospheric pressure were investigated in a thermobalance reactor using four coals of different rank. Effects of coal rank (lignite to semianthracite), particle size (0.18 to 1.00 mm), reaction temperature (700 to 900 °C) and concentration (30 to 100 vol%) of the reactant gas (CO2) on the conversion rate of char gasification were determined. The gasification reaction order and the reaction rate constant were determined from the conversion data, and the activation energy of the reaction was determined from the Arrhenius plot. Chemical reactivity of the char was correlated with the carbon content of the parent coals, particle size, partial pressure of CO2 and reaction temperature. The experimental conversion data are well represented by the unreacted shrinking core model in which chemical reaction is the rate-controlling step.