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Direct measurement of high-temperature CO2 gasification rate of pulverized coal chars at 1 atm

Geier, Manfred; Shaddix, Christopher R.

For oxy-fuel combustion with substantial flue gas recirculation, as is commonly employed, pulverized coal combustion occurs in the presence of elevated CO2 levels. Our previous investigations of pulverized coal char combustion in such atmospheres have suggested, through computational modeling of the experimental results, that CO2 gasification rates are sufficiently high under oxy-fuel combustion conditions to significantly influence the char combustion process. Experimental measurements of such rates under the relevant conditions (1 atm, T > 1700 K) are lacking. To address this, we have measured both the char particle temperature statistics and the char mass loss when a high volatile bituminous coal char and a subbituminous coal char are introduced into a high-temperature optical flow reactor with nearly 100% CO2. The experimental measurements show a temperature decrease from the gasifying particles (consistent with the strong endothermicity of the char gasification reaction) and show increasing mass loss with increasing residence time and temperature, as expected.