Advanced drying technology enables drying of rough rice and dedusting of rice husks to be carried out simultaneously in the same unit processor. This paper reports the efficiencyof dedusting of rice husks in a two-stage inclined cross flow fluidized bed dryer and thedrying kinetics of rough rice in batch fluidized bed dryer as well as the conceptual designof a hybrid drying – dedusting unit processor. Experimental works had been carried outusing rough rice (a Group D particle according to Geldart classification of powders) in a2.5 m height two-stage inclined fluidized bed column of cross sectional area of 0.61m x0.15m and a 3 m high batch fluidized bed dryer. The objectives of the study was toinvestigate the separation efficiency of dedusting of rice husk in the two-stage cross flowfluidized bed dryer and to study the drying kinetics of the drying kinetics of rough ricedrying in the batch fluidized bed dryer. The experimental results showed that thededusting separation efficiency at low superficial gas velocity gave unsatisfactoryseparation of merely 40% of rice husk. At higher superficial gas velocity, separationefficiency of rice husk as high as 93% was achieved. In addition, higher distributorinclination angle gave slightly improved separation efficiency. The drying kineticsshowed that the residence time that is required to reduce the moisture content of roughrice to 18% (intermediate storage moisture content for second stage drying) is 3 minuteswhereas the residence time that is required to reduce the moisture content to 13%(desirable final moisture content) is approximately 10 minutes regardless of the effect ofkernel cracking. It was also found that higher drying temperatures gave higher dryingrate. A conceptual design has been developed based on the results obtained in the studies.In order to maximize the heat utilization and to carry out two processes viz. dedustingand drying in one unit processor, it is suggested that drying – dedusting can be carried outin multistage mode where drying is taken place at each stage while dedusting is takingplace at the upper stage. This concept can be applied to a packed bed or a fluidized bedunit processor.
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