Abstract
Bamboo powder (particle size 0.2 mm) and three cube-shaped woods (1mm, 2mm and 3mm) were carbonized in the superheated steam (SHS) combined with far infrared heating (FIH), and the effect of sample size on carbonization rate was investigated. Carbonization temperature was adjusted at 270, 280, 290, and 300°C by regulating the SHS temperature at 180°C with the FIH temperatures at 375, 400, 425, and 450°C . Carbonization energies for the combined treatment were also compared with those for the carbonization treatment in SHS alone at 255, 265, 275, and 285°C . The generation rate of the SHS was the same for both carbonization treatments. The carbonization rate of each sample obeyed a first order reaction rate equation. Average values of the activation energy for the combined treatment of SHS with FIB and for the treatment in SHS alone were 137 kJ/mol and 149 kJ/mol, respectively. These values were almost the same as the activation energies for thermal decomposition of starch and cellulose under nitrogen gas. The relationship between the logarithmic values of the sample sizes and those of the carbonization rate constants was expressed as a linear curve at each carbonization temperature. Compared with the carbonization in the SHS alone, the combine treatment of SHS and FIB was much easier to make the carbonization apparatus in high carbonization temperature conditions with small additional heat. The higher the FIB temperature, the smaller the carbonization energy was obtained, because of shortening the carbonization time significantly.
