Rice Husk Fuel Pellet: Characterization on Physical and Thermogravimetric (TGA) Combustion Properties

Recently, the demand for biomass fuel pellet is increasing leading to the use of agricultural waste as the feedstock alternative to the wood pellet. In this study, the rice husk was developed into fuel pellet and characterized its physical and combustion properties. The pelleting used a flat-die roller type pelleting machine. The pre-treatments were reducing the size and mixing with a 4% gelatinized tapioca starch as the binder. The single pellet had an average diameter of 8 mm, length of 28.7 mm and weight of 1.8 g/pellet. The rice husk bulk density increased from 145 kg/m3 in raw form into 511 kg/m3 in pellet form. There were no significant different changes in pellet dimension after 14 days of pelleting. The combustion properties were analyzed using thermogravimetric analyses (TGA). The TGA analyses were conducted using oxygen at a flow rate of 50 ml/min; the heating rates were 10°/min, 20°/min and 30°/min heated up to 950°C. This study found that the ignition and the burnout temperatures were at about 276°C and 448°C, respectively. As to the non-woody characteristic of higher cellulose than woody biomass, the rice husk pellet had a higher conversion rate at lower temperatures than that of wood pellet.