Method and apparatus for increasing dehydrator efficiency

Abstract

A dryer consists of a horizontal drum rotated about its horizontal axis, containing flighting around its periphery, and coupled with a heat source, all of which is well known in the prior art. The dryer is open at only one end and provides an inner tubular member, centrally mounted coaxially in the drum which member presents a preheating chamber. Material to be dried is first fed into the inner tubular member at one end of the drum and is moved through the tubular member by a plurality of curved flights thus preheating the material in preparation for drying. The material is moved through the preheating chamber to the opposite closed end of the drum where it is deposited into the primary drying chamber of the drum. Flighting in the drum moves the material back toward the inlet end of the drum as it continues to be heated and dried and is then passed into a hopper where it is moved by a conveyor. A hot gas stream, which flows counter-current to the first direction of travel of the material being dried, is directed to the open end that presents both the inlet and the outlet, from the opposite end. An alternative embodiment of the invention provides a plurality of inner tubular members, each of which is provided with a plurality of internal curved flights. The material to be dried is passed through a first tubular member and into an adjacent tubular member by means of scoops such as described above.