Development of a Commercial Scale Vibro-Fluidized Bed Paddy Dryer

Abstract

The objectives of this research were to design, construct and test a prototype of vibro-fluidized bed paddy dryer with a capacity of 2.5–5.0 tons/h. Experimental drying conditions were: air flow rate 1.7 m³/s (1.9 kg/s), bed velocity 1.4 m/s, average drying air temperature 125–140°C, residence time of paddy approximately 1 minute, bed height 11.5 cm, fraction of air recycled 0.85 (1.6 kg/s) and vibration of intensity 1 (frequency 7.3 Hz and amplitude 5 mm.). It was found that moisture content of paddy was reduced from 28 to 23 % d.b. at a feed rate of 4821 kg/h. Electrical power consumption and average diesel oil consumption were 9646 W and 17.6 1/h, respectively. Specific primary energy consumption was 6.15 MJ/kg-water evap. Electrical power of blower motor and vibrator motor was 55 % as compared to electrical power of blower motor used in fluidized bed drying without vibration. For operation of 12 hours/day and 90 days/year, paddy drying cost was 1.50 baht/kg-water evap. (fixed cost 0.50 baht/kg-water evap. and operating cost 1.00 baht/kg-water evap., US$ 1 = 40 baht).