Fluidized-bed drying of parboiled rice

Abstract

Parboiled rice is one of the most important exported product of Thailand. Normally, the drying step in production of parboiled rice is performed by means of the conventional method of using sun drying. This uneffective method of drying needs to be improved since it requires high capital investment and labor work, and the quality of product obtained has no consistency. Fluidized-bed is ore of the techniques that has been successfully applied in drying many types of products. Therefore, this technique was selected to be used in drying of parboiled rice. First, the fluidized-bed column was designed and constructed. The operational systems, batch and continuous types, were studied. Four variables were taken into consideration, namely; time, air flow rate, temperature of hot air, and feed rate. The experiment was conducted and the data obtained was used to calculate the relationships between the rate of drying, the rate of heat transfer, the heat transfer coefficient, and the results obtained from milling were observed to find the optimum conditions in drying of parboiled rice by using fluidized-bed. It was shown from the experimental results that the fluidized-bed technique is suitable for drying of parboiled rice with high efficiency. The system used should be can- tinuous type operation with screw feeder since it gives a convenient, fast operation, and yields high quality products at any quantity required. The optimum conditions selected were 183°c of air inlet temperature at the air flow rate of 2 0.65 kg/sec.m2 and the production rate of 31.59 kg/hr.