Gasification reactivity of Canadian anthracite and semi -anthracite chars

Abstract

This paper presents the gasification reactivity in air of both the untreated and demineralized chars derived from Canmore (semi-anthracite) and Mt. Klappan (anthracite) coals using a thermogravimetric analysis technique. The effects of mineral content, particle size, and surface area on the reactivity of these chars were investigated. It was found that the gasification reactivity of the char decreased with increased particle size and decreased mineral content. The surface sub-fractal dimension, D, was determined from logarithmic plots of gasification reactivity against particle size. This parameter is a measure of the surface irregularity as experienced by species reacting at or with a surface and 2 < 13 < 3. The values determined for D were 2.78 and 2.40 for Canmore and Mt. Klappan chars respectively. The specific surface area measured by carbon dioxide adsorption at 298 K did not correlate with reactivity or particle size data whereas the results from mercury porosimetry indicated possible correlations.

Reactive fractal surfaces

“…The ideas presented in this report have been already utilized successfully by other groups, e.g., in coal gasification (30). 36 We also mention that for catalytic reactions a much wider range of DK was revealed:lb 0.2 < flR < 5.8; this is discussed in great detail elsewhere. 37 One conclusion from the catalysis study is worth, however, mentioning here: We found that Z)R > D situations originate there from a nonfractal scaling distribution; while this need not be the case for the heterogeneous surfaces discussed in this report, one should bear in mind that possibility as well.…”