DRYING PARBOILED ROUGH RICE IN STATIONARY, SEMI-FLUIDIZED, AND FLUIDIZED CONDITIONS

Fluidization in drying a moist product has been one unit operation attributed to acceleration of the drying process and improvement of quality of the dried product. A sample laboratory dryer capable of having stationary, semi-fluidized, and fluidized drying conditions in a single unit was designed and fabricated Drying experiments were conducted for parboiled rough rice with 10, 15, and 20 cm initial bed thicknesses at 40 to 80-degrees-C of drying air for each of the three drying conditions. It was observed that parboiled rough rice could be dried under semi-fluidized conditions without any significant milling loss and that drying time would also be largely reduced as compared to stationary-bed conditions. An extensive loss of head rice yield in milling and higher energy consumption took place in case of drying in fluidized bed. Recirculation of drying air at various proportions with fresh air was tried in semi-fluidized bed showing an improved drying efficiency and a higher milling yield.