Influence of Volume Shrinkage and Water Evaporation on Heat Transfer and Chemical Reactions During the Pyrolysis of A Cellulose-Powder-Packed Bed

Ken-ichiro Tanoue; Yuuki Hamaoka; Tatsuo Nishimura; Miki Taniguchi; Ken-ichi Sasauchi

Authors

Ken-ichiro Tanoue Department of Mechanical Engineering, Yamaguchi University, Japan Author
Yuuki Hamaoka Department of Mechanical Engineering, Yamaguchi University, Japan Author
Tatsuo Nishimura Department of Mechanical Engineering, Yamaguchi University, Japan Author
Miki Taniguchi Department of Mechanical Engineering, Yamaguchi University, Japan Author
Ken-ichi Sasauchi Department of Mechanical Engineering, Yamaguchi University, Japan Author

Keywords:

Cellulose pyrolysis, temperature plateau, effective thermal conductivity, volume shrinkage, water evaporation

Abstract

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.