In the present work a study of the production process of oil palm shells pellets is performed. The influence of the system parameters water content, particle diameter and temperature of the raw material are evaluated and its influence on the impact resistance of the obtained pellets is quantified. Also, the influence of these parameters on the pelletizing pressure is determined.The experimentation was done at a laboratory scale pelleting unit in which a ram (45 mm diameter, max force 152 kN) forces the biomass to extrude through a die with 14 holes of 6 mm diameter. The design was made to emulate the forces needed to introduce the biomass into and through the channels found in a commercial pellet mill. A preliminary experiment was executed to determine the necessary conditions to produce pellets in this particular pelleting unit by varying the parameters in the following ranges; temperature 60-100°C, particle diameter 0.25-1.00 mm and water content 10-25 % w.b. The experiment showed that the machine had not enough pressure to force the biomass into the die for particle sizes bigger than 0.5 mm with moisture contents below 20%, and pellets produced with moisture contents above 20 % w.b. crumbled easily. With this information a factorial experiment was executed to evaluate the effect of each parameter and their interaction on the impact resistance of the pellets, as well as the influence of these parameters on the pressure required to force the biomass through the die. The results showed that all of the parameters have a significant influence on both the impact resistance of the pellets and the pressure.
展开▼
