Abstract: A concurrent-countercurrent flow type grain dryer is described having an improved wet grain-drying air contacting arrangement. The dryer is in the form of a tower, with the grain passing from top to bottom by gravity flow. The tower has a wet grain bin at the top with intermediate drying zones and metering grain outlets at the bottom for controlling the rate of movement of grain through the tower. The drying zone is divided into several sections including at least two concurrent flow hot air drying zones with a steeping zone between each pair of concurrent flow hot air drying zones, followed by a countercurrent flow cooling zone. The use of two or more concurrent flow drying zones with intermediate steeping zones have been found to remarkably improve both the rate of flow of grain through the dryer and the moisture removal efficiency. Still greater efficiencies have been achieved by recycling the outlet drying air from one drying zone to the inlet drying air of a subsequent drying zone.

Abstract: A concurrent-countercurrent flow type grain dryer is described having an improved wet grain-hot air contacting arrangement. The dryer includes a wet grain bin having a horizontal floor assembly with a plurality of uniformly spaced openings with a tube member extending downwardly beneath each such opening. These tubes have insulated side walls and serve to deliver wet grain in response to gravity from the bin into a drying chamber. A hot air inlet duct is provided adjacent the tube members to deliver hot air into the space between the tube members and downwardly through a bed of grain in the drying chamber. The bottom of the drying chamber has metering grain outlets as well as cooling air inlet ducts, while air exhaust duct are provided intermediate the hot and cooling air inlets.