Description: Reaction rate kinetics were determined for the oxidation and gasification of oil shale char produced by retorting oil shale from the Anvil Points area of Colorado. Variables investigated included the effect of retorting rate (.3 to 17/sup 0/C/min) on the char quantity and quality as well as a range of concentrations and temperatures pertinent to char gasification. As long as the shale was retorted at rates higher than 0.3/sup 0/C/min or with purge velocities higher than 4 cm/min (STP), there was no effect of retorting on the char make. Neither did the assay of the shale (15 to 50 GPT) have any effect on the char oxidation activity. Char oxidation was first order with respect to both char and oxygen and had an activation energy of 23.2 kcal/mole, for shale which were either acid leached or had not undergone mineral decomposition. On the other hand, the CaO produced by calcite decomposition increased char oxidation by about one order of magnitude. Oxygen mass transfer measurements with the larger shale pieces pointed to the importance of convective mass transport during the oxidation of the first 40% of the char. Limited studies of the mineral reactions indicated that calcite was easily reformed from CaO, particularly when CO/sub 2/ was liberated at the surface from char oxidation. The LLL silication rate expression provided a good match to the experimental data. The data on the effect of H/sub 2/O on mineral decomposition are in agreement with LLL results. Analysis of the decomposition data during dolomite decomposition point to the possibility that CO/sub 2/ may inhibit the decomposition rate as well as prevent steam enhancement. A rate expression derived to describe CO/sub 2/-char gasification accounts for low apparent CO/sub 2/ reaction orders at high partial pressures. It was necessary to consider the role of the water ...
Date: October 1, 1979
Creator: Thomson, W. J.
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