US Patent 7568297 Grain drying aeration system

An improved vertical aeration system is provided for a grain bin having a sloped hopper bottom with a discharge opening. A pyramid frame includes legs with lower ends attachable to the hopper bottom. Concave perforated walls are attached to the legs. Braces extending between the legs provide structural support for the walls. An air duct extends upwardly and centrally into the interior of the frame, to supply air into the aeration system for flow outwardly through the perforated walls.