Pyrolysis Characteristics and Kinetics of Torrefied Wood and Coal Blends from Thermogravimetric Analysis

The properties of biomass can be improved to become an alternative source of fossil fuelsvia torrefaction. In this research, raw Cryptomeria japonica (WRaw) is torrefied at 250°C (TW250) and 300°C (TW300) for one hour. Each type of biomass (i.e. WRaw, TW250, TW300) is then mixed with an anthracite coal for test of pyrolysis. A thermogravimetry (TG) is used to examine the pyrolysis characteristics of fuel blends and five different biomass blending ratios of 100, 75, 59, 25 and 0 wt% are taken into consideration. The pyrolysis processes of WRaw and coal are characterized by three-stage decomposition, whereas four-stage thermal degradation is exhibited for the fuel blends. The experimental pyrolysis processes of fuel blends can be predicted well from the calculated results. This suggests that no interaction or synergistic effect occurs between raw or torrefied Cryptomeria japonica and coal. The pyrolysis kinetics of the fuel blends are also analyzed in the study. A decrease in biomass blending ratio has a trend to lower activation energy and activation energy. This is due to lower activity of coal in a pyrolysis environment.