Reactivity of heat-treated coals in steam

✍ Scribed by Angel Linares-Solano; Om P. Mahajan; Philip L. Walker Jr.

• Publisher: Elsevier Science
• Year: 1979
• Tongue: English
• Weight: 647 KB
• Volume: 58
• Category: Article
• ISSN: 0016-2361
• DOI: 10.1016/0016-2361(79)90148-0

✦ Synopsis

Reactivities

of seventeen 40 x 100 mesh (U.S.) coals charred to 1000°C have been measured at 910°C in 0.1 MPa of a N2-Hz0 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, CO2 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 H2 to steam has a marked retarding effect on char reactivity in most cases. However, in a few cases H2 acts as an accelerator for gasification.

The effect of particle size, reaction temperature and water-vapour pressure on char reactivity is considered