Kinetics of oil shale char gasification

Experimental work on gasification of oil shale char with CO/sub 2/ and steam are presented in this report. All of the gasification experiments were conducted with the same apparatus employed in the earlier oxidation work. As before, powdered shale samples (200 mesh) of previously retorted oil shale from the Parachute Creek member in Colorado were suspended from an electrobalance and placed in a furnace. In this way continuous gravimetric readings were available to monitor the consumption of the char. The off-gases were analyzed on a Carle gas chromatograph equipped with a Carbosieve B column. The retorted raw shale assayed at 50 GPT and was exposed to CO/sub 2/ pressures as high as 100 KPa and H/sub 2/O pressures as high as 75 KP/sub a/. Because there was evidence of the water gas shift reaction during steam gasification, separate experiments were also conducted in order to determine the rate of this reaction as a function of temperature and concentration of the reactant gases. The Livermore results predicted char consumption rates which were much higher than those observed for mixed gasification runs with P/sub CO/sub 2// > 10 KPa. The kinetic results from this work gave reasonable matches to the data atmore » P/sub CO/sub 2// < 15 KPa but also predicted much higher rates at CO/sub 2/ pressures greater than 20 KPa. The data exhibit a much lower char consumption rate than predicted. Also shown in this figure are the predictions assuming that only CO/sub 2/ gasification takes place. The assumption provides a reasonable match to the experimental data and suggests that the presence of CO/sub 2/ is somehow inhibiting steam gasification.« less