The Reactivity of a Porous Brown Coal Char to Oxygen between 630 and 1812° K

Abstract

Measurements have been made over the temperature range 630 to 1812 °K of the combustion rates and physical structure of sized fractions (89, 49 and 22 μm) of a brown coal char.

Above 900 °K the 89 and 49 μm fractions were found to react with rate control by the coupled processes of pore diffusion and chemical reaction on the pore walls. Below 760 °K these fractions reacted with rate control by chemical reaction alone, as apparently did the 22 μm fraction above 900 °K.

The “intrinsic reactivity” R_s of the char to oxygen was given for all three fractions and over the temperature range 630 to 1812 °K, by the empirical relation

taking the true order to be zero over the whole temperature range.