Experimental Investigation of Biomass Pellets and Pelletizing Process Using Hardwood and Switchgrass

Biomass fuel has been utilized as a renewable energy resource to replace or supplement fossil fuels. Combustion characteristics of biomass affect the utilization of biomass pellets. Activation energy, ash content, energy content, moisture content, density, and durability are a few parameters that are analyzed for ideal combustion. An ideal fuel can be created through analyzing multiple biomass materials and pelletizing procedures. The objective of this research is to improve biomass performance by investigating its pelleting parameters and the related combustion characteristics. A lab scale pelletizing process was developed with the pelletizing conditions being 150°C for 150 seconds under a pressure of 4500 psi. A total of 45 different types of pellets with a diameter of 2.5cm and a thickness of 5mm were created using the new pelletizing process. They had five different material mixtures (100% hardwood (HW), 75/25hardwood/switchgrass (HS), 50/50HS, 25/75HS, and 100% switchgrass (S)), three different original moisture contents (15%, 20%, and 25%), and 3 different amounts of binder (1/6, 1/12, and 0). Trends of the combustion characteristics to pelletizing process parameters were found. When the material mixture changes from pure hardwood to pure switchgrass, both activation energy decreases while ash content increases. When the binder decreases, activation energy increases as well as ash content while both energy content and durability decrease.