Pellet Feed Dryers
Pellets from dry pelleters may exit at up to 88°C and 17-18% moisture. The temperature must be quickly reduced to ambient or less and the moisture level to 10-12% or less for proper storage and handling. Pellets must therefore be cooled and dried. Moist pellets, if they are going to be converted to dry pellets, also need drying although their temperature is not normally much elevated during manufacture.
Coolers/dryers are of two basic types, horizontal and vertical.
In the horizontal type of cooler/dryer (Figure 22) the pellets are conveyed on a perforated steel mesh or moving belt through which a cooling air stream is passed. The horizontal method is best for 'sticky' dry pellets or for moist feeds (if it is necessary to dry the latter). Heat can also be applied to the air supplied to horizontal driers for reducing the high moisture contents of moist feeds to those of dry pellets for storage. This type of drier is standard in the production of noodles and spaghetti and other pasta. Horizontal dryers may be very large and are often arranged on several spatial levels.