Coal pyrolysis and gasification in a fluidized bed thermogravimetric analyzer

The kinetics and modelling of coal gasification were studied in the newly developed fluidized bed thermogravimetric analyzer. The total weight loss obtained from the fluidized bed reactor and the total gas product are in general agreement. The presented model for the micro-fluidized bed reactor encompasses the kinetics of coal pyrolysis as well as the gasification reactions. For coal pyrolysis, the resulting activation energies for the individual gases were 34.7 to 59.8kcal/mol. These values are 19 to 21% lower than those found in the literature for similar coals. This decrease of the activation energies of the endothermic pyrolysis reactions is attributed to a gradient of temperature of 185 to 209 degrees C. The obtained activation energy for the CO shift reaction is 46.6kcal/mol, increasing by 20% from the one used in the literature. This increase of the activation energy of such a mildly exothermic reaction represents an equivalent of 170 degrees C gradient of temperature. The effects of temperature on the yield and the composition of the gas product are studied. Experimental results and equilibrium data are also compared. The model shows reasonably good agreement with the experimental results, except for the water gas shift reaction.