Studies on Charcoal Block Production from Three Charcoal Types of Biomass Employing Screw Press Unit

摘要

The objective of this research was to study and develop bio-charcoal from agricultural wastes. The prototype machine consisted of a mixing tank, a screw conveyor, a hopper, a screw pressing unit, a transmission unit and a main frame. Three types of charcoal powder (cassava stump coal, assorted wood coal and coconut-shell coal) and three screw pressing speeds (115, 130 and 145 rpm) were studied. The experimental results indicated that the prototype gave the best combination of using a feed rate of 140 kg/h, screw pressing speed of 145 rpm and a mixing ratio by weight of assorted wood coal: coconut-shell coal: cassava starch: water content of 0.5: 0.5: 0.15: 1. The machine had a working capacity of 131.5 kg/h, specific energy consumption of 16.16 W-h/kg, bulk density of 676.0 kg/m~3, compressive strength of 0.235 MPa, heating value of 5527.3 cal/g and utilization efficiency of 27.79-29.56%. The charcoal block length, outer diameter and inner diameter were 15.01±1.62 cm, 4.12±0.05 cm and 1.23±0.12 cm respectively at an average moisture content of 7.31% (db.).