Concurrent-countercurrent flow grain dryer with air recycling means

In a continuous flow grain dryer of the type having an enclosed bin with a wet grain inlet at the top of the bin, grain outlets at the bottom of the bin, means for providing wet grain at the inlet, means for removing grain at the outlets, the improved concurrent counterflow structure for drying said grain comprising, in combination:

• a lower set of horizontal cold air inlet ducts extending the length of said bin and joined to means for directing cold air into said cold air inlet ducts;
• a first transverse set of horizontal exhaust ducts above the cold air ducts and transverse thereto, said first exhaust ducts connected to a hot air manifold;
• a first set of horizontal hot air inlet ducts parallel to the lower set of cold air inlet ducts and positioned above the first exhaust ducts, said first set of hot air ducts also connected to the hot air manifold;
• a second set of horizontal exhaust ducts above the first set of hot air inlet ducts and transverse thereto, said second set providing exhaust from the bin to the atmosphere;
• a second set of horizontal hot air inlet ducts parallel to the lower cold air inlet ducts and positioned above the second exhaust ducts, said second hot air inlet ducts also connected to the hot air manifold;
• and
• means for providing hot air flow to the hot air manifold for subsequent flow into said hot air inlet ducts whereby, air from said first set of exhaust ducts is combined with the hot air inlet flow to said hot air inlet ducts.