Counterflow preheating means for a concurrent countercurrent grain dryer

Claim 1

In a portable, continuous flow, grain dryer of the type having an enclosed bin with a wet grain inlet at the top of said bin and grain outlets at the bottom of said bin including a plurality of spaced, parallel horizontal hot fluid inlet ducts for directing a fluid drying medium downwardly through a bed of grain in said bin, a plurality of spaced, parallel, horizontal cold fluid inlet ducts for directing a fluid cooling medium upwardly through said bed of grain, said cold fluid inlet ducts positioned parallel to and below said hot fluid inlet ducts and spaced from one another to provide a plurality of grain discharge outlets from said bin, fluid inlet means at one end of said inlet ducts, means for adding wet grain through said wet grain inlet, means for withdrawing dry grain from said grain outlets, a first set of horizontal exhaust ducts means intermediate said hot and cold fluid inlet ducts and perpendicular thereto to receive and exhaust fluid medium flowing from said hot inlet ducts in a concurrent direction to grain flow and also exhaust cold fluid medium flowing from said cold inlet ducts in a countercurrent direction to grain flow, each of said exhaust duct means having outlets through said bin on opposite sides thereof and means for providing hot fluid to said hot inlet duct inlets and cold fluid to said cold inlet duct inlets, the improvement comprising: a second set of horizontal exhaust duct means above and parallel to said hot fluid inlet ducts and extending through opposite ends of said bin, said second set of exhaust duct means positioned to receive and exhaust a portion of said hot fluid medium flowing from said hot inlet ducts in a countercurrent direction to grain flow thereby preheating said wet grain immediately after it enters said bin.