COMPARISON OF THE THERMOBITUMINIZATION KINETICS OF BALTIC OIL SHALE IN OPEN RETORTS AND AUTOCLAVES; pp. 17–25
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doi: 10.3176/oil.2010.1.03Authors
Ille Johannes, L. TIIKMA, A. ZAIDENTSAL
Abstract
The kinetic models deduced for description of laboratory low-temperature pyrolysis of Baltic oil shale in open retorts and autoclaves are discussed. The apparent activation energies and frequency factors (E1-E4 and A1-A4) estimated for the two devices are compared approximating the process to the parallel-subsequent thermal decomposition of kerogen into three phases: volatiles, benzene extract and coke. Common for the both devices linearity, lnAi = 2.23 + 0.174 Ei, is revealed between the kinetic constants taken from the previous papers. It is shown that E1 for decomposition of kerogen into thermobitumen and oil (TBO) in autoclaves is lower than at decomposition into thermobitumen (TB) at retorting, whereas the values of E2 and E4, characteristic of decomposition of kerogen and TB into volatiles, are lower in open retorts than under pressure in autoclaves, and E3, characteristic of coke formation from high-molecular TB, is lower than in the case of oil-containing TBO. Time-dependencies of the yields of TBO, gas, solid residue and undecomposed kerogen at various nominal temperatures are predicted for pyrolysis in both devices under equal heating rates using the deduced unified model. It is shown that in the both devices secondary decomposition of TBO into coke and gas begins before the total decomposition of the initial kerogen has been completed, and the current decomposition degree of kerogen and yield of TBO are affected mainly by pyrolysis duration and temperature, whereas the reactor type has only a slight effect.
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doi:10.1016/j.jaap.2008.07.005
