Thermogravimetric Characterization of Irrigated Bermudagrass as a Combustion Feedstock

摘要

The bioenergy production industry can benefit from a greater understanding of potential differences among the various feedstock materials and production influences on thermochemical conversion processes such as combustion. The thermal degradation of biomass during combustion can quickly be assessed using thermogravimetric analysis (TGA) to provide a thermal profile for global characterization of reaction kinetics and temperatures associated with both the devolatilization and char combustion, as well as total volatile matter lost. In this work, the TGA technique was applied to understand combustion of Coastal bermudagrass [ Cynodon dactylon (L.) Pers.] hay produced under a control treatment of commercial N fertilizer without irrigation along with eight different subsurface drip irrigation (SDI) treatments. These eight treatments consisted of commercial N fertilizer or advanced-treated swine wastewater effluent, each irrigated at two (75% and 100% of estimated evapotranspiration) irrigation rates and two lateral SDI spacings (0.6 and 1.2 m). While thermogravimetric (weight loss) profiles of the treatments were almost identical and indicated three distinct combustion weight loss steps, some variations among the treatments were noted in the differential thermal analysis profiles. When compared to commercially fertilized bermudagrass, Coastal bermudagrass irrigated with advanced-treated swine wastewater had both greater mass loss associated with active combustion and a higher transition temperature leading to char combustion (364.9°C vs. 372.5°C). This higher temperature requirement for char combustion of the hay irrigated with effluent was a direct result of a greater activation energy value required to initiate char combustion (97.9 kJ mol -1 for commercial vs. 105.1 kJ mol -1 for effluent). Consequently, char combustion required greater activation energy than the first active combustion stage. Among the SDI spacing treatments, Coastal bermudagrass irrigated using the wider SDI spacing provided greater amounts of energy per mass of dry material (11.16 vs. 12.06 kJ g _converted -1 )