| The objective of this research is to explore the feasibility of thermal pretreatment of biomass by characterizing solid products for succeeding process to generate renewable fuels. Two processes were evaluated: wet and dry torrefaction. In wet torrefaction, biomass is treated with hot compressed water in the temperature range of 200--260°C, and in dry torrefaction, biomass is treated with nitrogen, at 250--300°C. Both processes produced a solid product with enhanced fuel value. The equilibrium moisture content (EMC) of solids produced by both processes is decreased from that of the biomass feedstock. The EMC of biomass pretreated by either processes decreases with increasing pretreatment temperature, and wet process produces a more hydrophobic solid than that produced by dry torrefaction. A new model, Vasquez Coronella Sorption Model (VCSM), was used to fit the experimental data and the fitted parameters have some physical significance that can explain some underlying behavior of pretreatment process. The mass and energy balances in wet torrefaction were established for the temperature at 200, 230, and 260°C. Products include pretreated solid, simple sugars and sugar derivatives, volatile acids, and gases. The mass of the pretreated solid decreases with reaction temperature. The heat of reaction (DeltaH) at each temperature is very close to zero while the results of an error analysis indicate that DeltaH is indistinguishable from zero. |
