Pelletization of torrefied palm kernel shell by using different binding agents

Abstract

Palm kernel shell (PKS) pellets are used as fuel for boilers due to their uniform shape and carbon content. However, the pellet's low mechanical properties can cause a high level of dust, increased fire explosions, and become health hazards to workers, which become challenging during transportation and storage. In this study, four types of binders, carboxymethylcellulose, lignin, starch, and glycerol, were used to improve the mechanical durability of torrefied PKS pellet. The PKS was torrefied at 250 ℃ for 30 min and pelletized at 130 ℃ and 12 MPa. The torrefied pellets were characterized according to their chemical and physical properties. Results indicate that the density of pellets using all binders achieved more than the standard value (600 kg/m3). Overall, the carboxymethylcellulose could be used as a suitable binder that gives the highest mechanical durability (4449 N), low ash content (4.2 wt%), and improved HHV (20.68 MJ/kg) compared to other binders for torrefied PKS pellets to be used as fuel for power generation.