US 5,634,281 AGranted

Multi pass, continuous drying apparatus

AssigneeUniversal Drying Systems, Inc.

InventorJames E. Nugent

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Abstract

An apparatus for drying moist solid or semi-solid materials, such as sewerage sludge, municipal waste, industrial waste, agricultural waste, and the like, includes a dryer unit having a plurality of stacked heating chambers, each of the heating chambers above the lowest heating chamber having a conveyor belt for transporting the material through the associated heating chamber and depositing it on a lower heating chamber, the lowest of the stacked heating chambers including a conveyor belt for transporting the material therethrough and discharging the material from the dryer unit. The apparatus utilizes a combination of convective heat transfer, in the form of a heated gas which rises upwardly through the dryer unit through successive heating chambers, and radiative heat transfer, provided by radiative heating units disposed above the conveyor belt in each heating chamber. The speed of the conveyor belts can be individually controlled to allow more effective utilization of the drying and material handling capacity of the drying apparatus. The stacked heating chamber arrangement results in a more compact dryer which requires less floor area than a dryer having a single linear heating chamber. The stacked heating chamber arrangement also results in lower heat losses through the walls, floor, and top of the dryer housing.

Claims18

Dependent claims

A continuous drying apparatus for removing liquid from a moist solid or semi-solid material, comprising:

a housing generally having a floor, opposing sidewalls, and a top, said housing enclosing a dryer volume which is divided into a plurality of stacked heating chambers by plates extending between the opposing sidewalls;
a plurality of conveyor belts;
each of said heating chambers containing one of said plurality of conveyor belts, the conveyor belt in each of the heating chambers above the lowermost heating chamber transporting said solid or semi-solid material through said heating chamber and depositing said solid or semi-solid material on a different conveyor belt in an adjoining lower heating chamber, the conveyor belt in the lowermost of said heating chambers transporting said solid or semi-solid material through said lowermost chamber and to an outlet for discharging said solid or semi-solid material from said drying apparatus;
at least one radiative heating unit mounted above said conveyor belt in at least one of said heating chambers so that radiation is directed downwardly onto material carried by said conveyor belt;
an inlet feed hopper for depositing said material onto said belt in the uppermost of said plurality of stacked drying chambers;
and
a gas outlet for exhausting gas from the uppermost of said stacked heating chambers wherein at least one of said heating chambers includes at least one vertically arranged baffle which extends across the at least one heating chamber transverse to the conveyor belt disposed within the at least one heating chamber and which divides said at least one heating chamber into a plurality of heating zones to facilitate localized temperature control in said heating chamber.

4 more elements

Dependencies are inferred from the claim text.