CONTINUOUSDRYING OF WHEAT WITH HOT SAND

delivery section. The cylinder was driven by a small gear meshing with a larger gear fitted to the rotating cylinder. The angular speed of the cylinder was varied using a variable speed reduction system driven by a 250-W electric motor. Two hoppers, one for damp grain and one for hot sand, were mounted above the drying section inlet. These hoppers delivered the grain and sand into the metering head. The metering head was used to deliver the desired sandto-grain mass ratio into the drying section. Adjustable legs were installed on the frame of the machine to control the angle of inclination of the dryer. Further details and the schematic diagram of the dryer are given elsewhere (Lapp and Manchur 1974). The residence time of the sand and grain in the dryer section was regulated by vary ing the cylinder slope, the rotational speed or the feed rate. The sand, after screening through the separating section, was recir culated to the sand hopper by a 3.05-m bucket elevator and a 15.2-cm-diameter pipe insulated with fiber glass. The sand hopper contained ten 230-V, 2-kW elec tric heating elements. These heaters were placed on three separate circuits with cir cuit breakers on each circuit. A fan of 17m3/min capacity was installed at the end of the cooling section. The fan helped to cool the grain and removed moisture from the drying section.