Influence of volume shrinkage and water evaporation on heat transfer and chemical reactions during the pyrolysis of a cellulose-powder-packed bed
2018
Nishimura, Tatsuo | Hamaoka, Yuuki | Taniguchi, Miki | Sasauchi, Ken-ichi | Tanoue, Ken-ichiro
Heat and mass transfer during the pyrolysis of a cellulose-powder-packed bed has been investigated numerically to reveal volume shrinkage and water evaporation. From the calculation results for the temperature and velocity vector distributions, it was found that there is a quasi-steady state during pyrolysis because the gas volume increased on the top and side walls of the bed and then the effective thermal conductivity decreased. There were two plateaus in the time course of the temperature and two peaks in the time course of the generated gas flow rate for the experimental results. The calculated temperature with not only volume shrinkage but also additional water content reproduced the time course of the temperature after the second plateau. Furthermore, the calculation gas flow rate agreed quantitatively with the experimental ones, which had two peaks during pyrolysis. In order to reproduce the heat and mass transfer between the first and second plateaus in cellulose pyrolysis, it is necessary to investigate the modified calculation model with the heat of chemical reactions.
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