Effect of feed rate and screw pressing speed to the performance of a charcoal block pressing machine

Abstract

This study aimed to examine the effects of feed rate and screw pressing speed on the performance of a cassava-stump charcoal block pressing machine, as well as to design and develop a prototype. The machine consists of several components, including a mixing tank, screw conveyor, hopper, screw pressing unit, transmission system, and main frame. The experiment tested feed rates of 80, 100, and 120 kg/h and screw pressing speeds of 80, 95, 110, and 125 rpm. Results showed that the produced charcoal blocks had an average length of 13.91±1.62 cm, an outer diameter of 4.12±0.05 cm, an internal diameter of 1.23±0.12 cm, and a moisture content of 3.31% (dry basis). When tested at a screw pressing speed of 125 rpm and a feed rate of 120 kg/h, with a mixture ratio of cassava stump charcoal, cassava starch, and water at 3.00:0.45:4.00 kg, the machine achieved a production capacity of 111.7 kg/h, specific energy consumption of 13.35 w-h/kg, a bulk density of 505.3 kg/m³, a charcoal strength ranging from 82.14 to 159.51 kN/m², and a heating value of 5113.3 cal/g.