Physical Properties of Corn Residues

Abstract

Corn residues (cobs, leaves and stalks) are abundantly available renewable materials that can be used as an energy source in gasification and combustion systems. Proper understanding of the physical properties of these materials is necessary for their use in thermochemical conversion processes. The physical properties (moisture content, particle size, bulk density and porosity) of corn cobs, leaves and stalks were determined in this study. The moisture contents were 6.38, 7.92 and 6.40% of the cobs, leaves and stalks, respectively. The cobs had the highest weight percentage (18.23%) of the small particles (<0.212 mm) and the leaves had the highest weight percentage (40.10%) of large particles (>0.850 mm). Most of the stalk particles (84.82%) were in the range of 0.212-0.850 mm. The cob particle size had a normal concave (inward) distribution between particle sizes 0.106 mm (18.23 weight %) and 0.925 mm (25.26 weight %) with the lowest weight percentage (5.30 weight %) at 0.390 mm particle size while the stalk particle size had a normal convex (outward) distribution between particle sizes 0.106 mm (8.49 weight %) and 0.925 mm (6.69 weight %) with the highest weight percentage (23.47 weight %) at the 0.605 mm particle size. The leaves had an increasing trend of particle size distribution between the particle sizes 0.106 and 0.925 mm. The average particle sizes for the cobs, leaves and stalks were 0.56, 0.70 and 0.49 mm, respectively. The average bulk density was 282.38, 81.61 and 127.32 kg m^-3 for the corn cobs, leaves and stalks, respectively. The average porosity was 67.93, 86.06 and 58.51% for the corn cobs, leaves and stalks, respectively. A positive relationship between the average particle size and the porosity was observed for the corn residues. The differences in the physical properties among the corn residues (cobs, leaves and stalks) observed in this study are due to variations in the compositions and structures of these materials.