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Design, Fabrication and Evaluation of a Direct-Fired Corncob Furnace for Corn Drying

Jessie Pascual P. Bitog1, Jessie C. Elauria2, Arnold R. Elepano2 and Arsenio N. Resurreccion3


The performance of a fabricated direct-fired corncob furnace was evaluated to determine best combinations of operating parameters involving fuel feed rate, combustion air, and fuel size. The furnace had the following components: hopper; rotary feeder; variable motor; inclined grate; and horizontal grate. The furnace wall was made up of cement and red volcanic cinder.

Result showed no trend from the computed burning efficiency when the fuel feed rate was varied. All the levels of combustion air and fuel size significantly affect the burning efficiency of the furnace. All levels of the independent parameters revealed significant differences in the furnace efficiency. In terms of furnace capacity, all independent parameters revealed no significant differences.

Theoretically, the furnace can supply the required energy needed for the two-ton flat bed dryer to dry corn grains from 28% to 12% moisture content for 8 hours of operation. Fuel feed rate of 15 kg/hr with 3300 cubic meter per hour combustion air and fuel size >2.5 cm is the best operating condition to operate with high furnace efficiency. The average computed furnace efficiency for this operating condition is 89%.

Keywords: direct-fired corncob furnace, fuel feed rate, combustion air, and fuel size

1Instructor, College of Engineering, Nueva Vizcaya State University, Nueva Vizcaya, Philippines; 2Associate Professor, and 3Professor, College of Engineering & Agro-Industrial Technology, University of the Philippines Los Baños, Philippines.