keywords: Column flash dryer, cassava starch, drying temperature, Simprosys
A column flash drying unit for processing cassava starch was designed, constructed, assembled and test run to process 20 kg/h of dry starch. The column flash drying unit consist of the fan, the heater, the dryer column and the cyclone. Simprosys 2.1 software package was used to simulate the drying operation and mass/heat balances calculated to determine the dryer design variables. From the results generated, it was found that the fans power input and outlet velocity were 0.426 kW and 14.889 m/s, respectively. The heat duty evaluated for the heater was 8.281 kW. The drying chamber consists of a conical base with specially arranged blade ring at an angle of 9o to the horizontal. The dryer chamber diameter and length were 0.184 and 1.657 m, and the cyclone diameter was evaluated as 0.305 m. The column flash drying unit was tested using 4 kg of freshly prepared cassava starch (with moisture content of 68.75%). 2.15 kg of dry cassava starch was recovered from the system in 10.8 minutes. The moisture content of the cassava starch was reduced from 68.75% to 8.50% wet basis at air velocity of 13.20 m/s and temperature of 105oC. The thermal efficiency of the fabricated dryer was determined to be 60.21%.
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