Analysis of Multiple Gas-Solid Reactions During the Gasification of Char in Oil-Shale Blocks

摘要

A mathematical model is presented for the major high-temperature chemical reactions occurring in the absence of O sub 2 within a block of spent oil shale: decomposition of dolomite and calcite, char pyrolysis, carbon gasification with CO sub 2 and H sub 2 O, water-gas shift, and intrablock diffusive and convective flow of CO sub 2 , CO, H sub 2 and H sub 2 O. To establish the validity of the computer model, experiments were performed on cylindrical blocks of oil shale having a mass of about 8 kg. The blocks were heated in an electric furnace and swept with heated gas of controllable composition that included steam. Maximum block surface temperatures of 750 exp 0 C and 815 exp 0 C were used. The computer model produced excellent simulations of the experimental carbon gasification reactions. Accurate simulation of the carbon gasification reactions required the use of intrinsic rate coefficients that were substantially lower than those previously measured for powdered samples. The water-gas shift had an almost negligible effect on the rate of carbon gasification in all runs. (ERA citation 06:018062)