The effect of pore structure on the char-steam reaction



The kinetics of the char-steam gasification reaction and the accompanying pore structure changes have been investigated experimentally and interpreted through the use of the random pore model of Bhatia and Perlmutter (1980) and its extensions developed in this study. To allow model evaluations, surface areas and pore-size distributions were obtained for various partially-reacted char samples. Surface areas follow the reaction rates as a function of conversion, supporting the interpretation that the reaction of porous char with steam is governed by the structural changes that occur as conversion proceeds. Reaction rate constants were obtained from the kinetic data.

A pyrolytic change of char mass was observed during the heatup period from room temperature to reaction temperature for each of the two char samples tested. This results in a significant increase in surface area and a decrease in pore structure parameter. It is shown that this pore structure parameter is very sensitive to changes in conversion when the initial parameter is large and the conversion is small.