Drier coolers are vertical, cylindrical vessels with a multitude of horizontal trays. The desolventized and toasted meal enters at the top and is supported by the tray. The meal is mixed above each tray, and conveyed downward from tray to tray, by agitating sweeps anchored to a central rotating shaft. The trays of the DC are designed with an upper plate, lower plate, and structural members between designed to distribute low pressure air vertically into the meal layer supported above. The DC has two different types of trays; air drying trays and air-cooling trays.
The DC air drying trays are designed with an upper plate, lower plate, and structural members between designed to hold low pressure air. The air-drying trays are designed with a plurality of apertures across their entire upper surface to evenly introduce hot air into the meal. The size and quantity of apertures is calculated based upon the design air flow rate to provide a pressure drop of 0.02 to 0.03 bar. These apertures are generally small round holes, with some DCs also using narrow slots. The DC many have from 1 to 6 air dryer trays. The number of air-drying trays is determined to allow adequate hot air to pass through the meal to remove moisture to the target value