Effect of moisture content during preparation on the physicochemical properties of pellets made from different biomass materials

Abstract

The influence of moisture content was investigated relative to the pellet forming process and the pellet properties. Three different types of raw biomass (pine sawdust, corn straw, and peanut shell) were pelletized by hot pressing at different moisture levels (12%, 14%, and 16%) in a pellet mill with horizontal and ring type dies to investigate its physical property indexes of durability, pellet density, and combustion performance. The results of the study showed that pellet density and heating value were related to the moisture content. The maximum pellet density of the fuel pellets of sawdust, corn straw, and peanut shells was 1180 kg/m3, 1220 kg/m3, and 1130 kg/m3, respectively. The drop resistance and deformation resistance of pine sawdust and corn straw decreased with increased moisture content, but peanut shell initially increased with the increase of moisture before decreasing. The comprehensive combustion index of corn straw (14.03) was the highest during the combustion performance analysis in comparison to sawdust (11.10) and peanut shell (10.00). Overall, the optimal moisture content of sawdust, corn straw, and peanut shell was 12%, 12%, and 14%, respectively, and the combustion performance of the pellets made from corn straw was superior compared to the other two feedstocks.