Densification characteristics of corn cobs

Corn cobs are potential feedstocks for producing heat, power, fuels, and chemicals. Densification of corn cobs into briquettes/pellets would improve their bulk handling, transportation, and storage properties. In this study, densification characteristics of corn cobs were studied using a uniaxial piston-cylinder densification apparatus. With a maximum compression pressure of 150 MPa, effects of moisture content (10 and 20% w.b.), particle size (0.85 and 2.81 mm), and preheating temperature (25 and 85°C) on the density and durability of the corn cob briquettes were studied. The diameter of the corn cob briquettes was about 19.0 mm. It was found that the durability (measured using ASABE tumbling can method) of corn cob briquettes made at 25°C was zero percent. At both particle sizes, preheating of corn cob grinds with about 10% (w.b.) moisture content to 85°C produced high density (unit briquette density of >1100 kg m^-3) and durable (about 90%) briquettes from corn cobs. Improved binding of corn cob particles due to preheating to 85°C was due to the activation (softening) of natural binders such as lignin, starch, and protein in the corn cobs at the elevated temperature of 85°C.