Kinetics of the gasification of a Rio Turbio coal under different pyrolysis temperatures

Abstract

The kinetics of the gasification reaction of char with CO 2 in a fix bed reactor was studied by gas chromatography. The char was produced by devolatilizing raw coal from Rio Turbio, Argentina in a drop tube furnace (DTF). Two chars were prepared and characterized for pyrolysis temperatures of 1123 and 1223 K. The experimental conditions for chemical reaction rate control were obtained in the range of temperatures between 1098 and 1193 K. Under those conditions the influence of gasification temperature and carbon dioxide concentration was analyzed. Similar values of activation energies were obtained for both chars, and only a slight decrease in reactivity was detected for the highest pyrolyzation temperature. Regarding the effect of carbon dioxide concentrations, no influence in the gasification rate was obtained for the char pyrolyzed at 1223 K, whereas a reaction order of about 0.5 was obtained for CO 2 concentrations below 30% for the other char. Two reaction models were applied that fairly fit the experimental data: the random pore model and the grain model. The reaction rate equations according to the different models were determined.