Effects of Die Size on Pellet Quality for Cellulosic Ethanol Manufacturing

Cellulosic ethanol can be used as a sustainable alternative transportation fuel. A major obstacle to restrict large-scale cellulosic ethanol manufacturing is low bulk density of cellulosic biomass that increases costs during transportation, storage and application of biomass. Biomass pelleting can significantly increase density of biomass. Pellets with high density can be handled, transported, stored and utilized easily. Ring-die pelleting, a traditional pelleting method, is widely used in biomass densification industry. This paper reported an experimental study to compare pellet quality (such as equilibrium moisture content, density, and durability) and microstructure of corn stover processed by a ring-die pellet mill with three different die sizes. Results showed that round and bigger die (32 mm instead of 9 mm) results in higher pellet density, durability, and lower equilibrium moisture content.