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Reactivity of heat-treated coals in steam

Authors
Journal
Fuel
0016-2361
Publisher
Elsevier
Publication Date
Volume
58
Issue
5
Identifiers
DOI: 10.1016/0016-2361(79)90148-0

Abstract

Abstract Reactivities of seventeen 40 × 100 mesh (U.S.) coals charred to 1000 °C have been measured at 910 °C in 0.1 MPa of a N 2H 2O mixture containing water vapour at a partial pressure of 2.27 kPa. Char reactivity decreases, in general, with increasing rank of the parent coal. The chars show a 250-fold difference in their reactivities. Results suggest that gasification of chars in air, CO 2 and steam involves essentially the same mechanism and that relative gasification rates are controlled by the same intermediate oxygen-transfer step. Removal of inorganic matter from raw coals prior to their charring or from chars produced from raw coals decreases the reactivities of lower-rank chars, whereas reactivities of higher-rank chars increase. Addition of H 2 to steam has a marked retarding effect on char reactivity in most cases. However, in a few cases H 2 acts as an accelerator for gasification. The effect of particle size, reaction temperature and water-vapour pressure on char reactivity is considered.

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