Tuesday, April 30, 2013
Exhibit Hall
Thermal preconversion technologies have demonstrated promise for transforming raw biomass into feedstock material that has improved milling, handling, storage and conversion properties as well as increased structural homogeneity. Thermal treatment of biomass ranges from simple (non-destructive) drying to more severe treatments that cause devolatization, depolymerization, and carbonization. Treatment in the temperature range 200-300°C in the absence of oxygen is known as torrefaction and has received considerable research attention recently due to the attractive properties of the resulting (torrefied) material. Nearly all published data has been obtained using either lab-scale thermal treatment systems that produce 1-5 kg of material per batch or thermogravimetric (TGA) instruments that analyze less than 1 g of material. It is unclear how these results apply to commercial-scale thermal treatment processes, which are expected to operate on a continuous-feed basis. This work compares key treatment parameters and their impacts on material properties for corn stover and switchgrass treated in different equipment systems, including TGA (approximately 1 g), batch (approximately 3 kg per batch), and continuous-feed (approximately 20 kg per hour) systems. Process temperatures that are explored include 180, 230, and 270°C. Effluent gas production, mass yields, and thermochemical properties of the treated material of the different treatment systems are compared to establish the impacts of process scale on the reaction products.