Thermal Conversion Characteristic of Pelletized Jatropha Residue and Glycerol Waste

Adverse environmental effects resulting from fossil fuel usage as well as foreseeable conventional energy depletion lead to the exploration of alternative fuel materials especially the renewable ones. In this work, characterization of synthetic fuel material formed by pelletization of Jatropha residue (physic nut) using glycerol waste as a binder was carried out in order to investigate the feasibility of utilizing these waste materials as another renewable energy source. Both wastes are by products from biodiesel manufacturing process. Synthetic fuel materials of Jatropha residue mixed with 0–50% glycerol waste were formed to length of about 11 mm and diameter of about 13 mm under pressure of 7 MPa in a hydraulic press. Maximum compressive stress (2.52×105 N/m2) of the fuel pellet occurred at 10% glycerol waste. Thermal conversion characteristic of solid fuel was studied by using single particle reactivity testing scheme at temperature of 500–900°C under partial oxidation atmosphere. In general, higher glycerol content in solid fuel as well as oxygen concentration in reacting gas resulted in greater decomposition rate from 0.006–0.110 g/sec. Burning started with a relative short drying phase, followed with a longer pyrolysis time and thereafter the dominated char combustion time which took around 35–57% of total conversion time. The average total conversion time varied from 26 to 288 sec, depended mainly on reaction temperature. Higher glycerol content resulted in char with lower density and higher shrinkage with greater porosity. Greatest changes in pellet diameter, height, and density of 75.6%, 89.2%, and 91.5%, respectively, were exhibited at 5% oxygen atmosphere and 900°C. The results suggested that Jatropha residue mixed with glycerol is suitable for utilization as quality solid fuel.