Kinetics analysis and estimation of energy properties of torrefied biomass

Torrefaction is one of the promising treatments for reforming conventional solid biofuels, and torrefied solid biofuels have come to attract attention as an alternative to coal. When torrefied solid biofuels are utilized or produced, energy properties such as higher heating value (HHV) and energy yield of torrefied solid biofuels are quite important. There are two aims of the study. One is to present the HHV evaluation method by lumped-parameter pyrolysis kinetic models with high evaluation accuracy. The other is to present the simple correlation to evaluate HHV without depending on three biomass species. From the comparison between the HHV evaluation method and experimental data, it is clarified that the proposed HHV evaluation method based on the two-step pyrolysis kinetic model can be useful to evaluate the HHV of torrefied biomass for three biomass samples with high evaluation accuracy, 5% or less. The linear correlation between HHV enhancement factor and mass yield of torrefied biomass is found regardless of three biomass species in the range of torrefaction mass yield larger than 0.6.