Factors affecting the biomass pellet using industrial eucalyptus bark residue

Eucalyptus is utilized in the timber and paper industries. The eucalyptus bark must be peeled off during the production process, which results in a large amount of biomass residue. The objectives of this research were (i) to study the physical properties of eucalyptus bark, (ii) to investigate the crushing process using a hammer mill, and (iii) to examine the pelletizing factors of biofuel from eucalyptus bark residue using a pellet machine. Eucalyptus bark was crushed to reduce particle size and then sieved through different screen sizes (3, 4, and 5 mm) at a drum speed of 1200 rpm. The resulting eucalyptus powder was used to study the pelletizing factors of biofuel at various levels of moisture content: 17.69, 20.21, 24.27, and 26.74% w.b. and various pelletizing speeds of 250, 275, and 300 rpm. It was found that the eucalyptus powder could be pelletized at a speed of 275 rpm. Pellets with screen sizes of 3 and 4 mm could be pelletized at a moisture content of 17.69% w.b., while a screen size of 5 mm could be sued to pelletize at a moisture content of 20.21% w.b. The specific energy consumption from the particle size reduction process to the pelletizing process ranged from 667.92 to 854.64 kJ/kg. The results of bulk density, durability, and fines were 603.20-645.73 kg/m³, 96.34-96.88%, and 1.83-2.02%, respectively. The heating value was 16.19 MJ/kg. The energy value was calculated by using a eucalyptus pellet as boiler fuel (at a boiler efficiency of 38%). Eucalyptus pellets have the potential to produce energy worth 644 million THB/year or 20.6 million USD/year.