Specific Energy Requirement for Compacting Corn Cobs

Abstract

Corn cobs are potential feedstock for producing heat, power, fuels, and chemicals. Densification of corn cobs into briquettes/pellets would improve their bulk handling, transportation, and storage properties. The objective of this study was to investigate the densification characteristics and specific energy requirements for the compression of corn cobs under four pressure levels (10, 12, 14, 16MPa) and with two particle size levels (2.41mm, 0.86mm). The compression behavior of ground corn cobs was studied using a hydraulic press briquetteing machine whose cylindrical die diameter was about 30 mm. The corn cobs moisture content and preheat temperature before compaction was 10% (w.b.) and 75 °C, respectively. The cylindrical die temperature was maintained at 90 ± 5 °C. It was found that the briquette density ranged from 809 to 1043 kg m-3; while the total specific energy requirement to compress and extrude briquette ranged from 17 to 26 MJ t-1, with an increase in pressure. Particle size had also a significant effect on briquette density and specific energy requirement. The finer corn cob grinds (0.86mm) resulted in higher density and lower specific energy requirement than the coarser corn cob grinds (2.41mm). New statistical models were developed to describe the total specific energy consumption of ground corn cobs during densification using a multiple linear regression analysis.