Crop drying apparatus

Claim 2

Crop drying apparatus comprising a rotatable drum mounted with its axis extending generally horizontally, means dividing the interior of the drum into a plurality of outer chambers for containing crop to be dried, and a central, axially-extending, multi-sided duct having an inlet at one end portion to receive an axial air flow, doors on the outer surface of the drum, each door being associated with a respective chamber to enable filling or discharge of the crop into or from the chamber, each chamber having means defining an inner perforate area to permit flow of air from the duct into the chamber to dry the crop therein and means defining an outer perforate area to permit discharge of moisture-laden air from the chamber to the surrounding atmosphere, and the inner perforate area of each chamber leading the associated outer perforate area in the normal direction of rotation of the drum, and means for controlling the air flow through the inner perforate area during rotation of the drum.

Claim 3

Apparatus according to claim 1, wherein the duct is of generally triangular cross-section.

Claim 4

Apparatus according to claim 2, further comprising rakes extending into the interior of each chamber.

Claim 5

Apparatus according to claim 1, wherein each perforation of the outer perforate areas has a diameter of between about 0.06 ins. and 0.1 ins, and each outer perforate area has an open area of at least 30%.

Claim 6

Apparatus according to claim 1, wherein the total open area of the outer perforate areas is between about 1/10 and 1/3 of the peripheral surface area of the drum.

Claim 7

Apparatus according to claim 1, wherein each inner perforate area is composed of first and second groups of perforations, the first group being arranged upstream of said second group with respect to the direction of air flow through the duct, and the open area of the first group being greater than that of the second group.

Claim 8

Apparatus according to claim 1, wherein the means for controlling the air flow through the inner perforate areas comprises flaps mounted in the duct adjacent the inner perforate areas.

Claim 9

Apparatus according to claim 7, further comprising a generally circular cam track, and cam followers engageable with the track and linked to the flaps, said followers being movable around the track during rotation of the drum to effect opening and closing movements of the flaps.

Claim 10

Apparatus according to claim 8, wherein the cam track is pivotal about the axis of the drum into a selected angular position and the cam track is so arranged as to permit rotation of the drum in either direction.

Claim 11

Apparatus according to claim 7, wherein the flaps are controlled so that during each revolution of the drum, air flows into each chamber for a total period equivalent to between about 1/3 and 2/3 of a revolution.

Claim 12

Apparatus according to claim 10, wherein the flaps are controlled so that air flows into each chamber in two discrete periods.

Claim 13

Apparatus according to claim 11, wherein each of said discrete periods extends over about 1/6 of a revolution.

Claim 14

Apparatus according to claim 10, wherein the duct defines an inner surface of each chamber, and each flap is controlled so that when its associated chamber is moving downwardly with its said inner surface inclined at such an angle that the crop begins to slide along the said inner surface, the flap is opened to permit air flow into the chamber and the flap is closed when the said inner surface is approximately vertical, the flap being opened again during upwards movement of the chamber.

Claim 15

Apparatus for drying forage crops comprising a drum having a generally horizontal axis, means for rotating the drum about its axis, means dividing the interior of the drum into at least three outer chambers for containing the crop to be dried and a central, axially-extending, flat-walled multi-sided duct arranged to receive an axial air flow, each side of the duct defining an inner wall of each respective chamber and the peripheral wall of the drum defining an outer wall of each chamber, a door associated with each respective chamber to enable filling or discharge of the crop into or from the chamber, said doors being located on the outer peripheral surface of the drum, the inner wall of each chamber comprising an inner perforate area located adjacent a corner portion of the duct to permit flow of air from the duct into the chamber to dry the crop therein and the outer wall of each chamber comprising an outer perforate area to permit discharge of moisture-laden air from the chamber to the surrounding atmosphere, and the inner perforate area leading the associated outer perforate area in the normal direction of rotation of the drum, flaps for controlling the air flow through the inner perforate areas, said flaps being located inside the duct adjacent the corner portions thereof, and means for operating the flaps during rotation of the drum.

Claim 16

Apparatus for drying forage crops comprising a drum having a generally horizontal axis, means for rotating the drum about its axis, means dividing the interior of the drum into at least three outer chambers for containing the crop to be dried and a central, axially-extending, flat-walled multi-sided duct arranged to receive an axial air flow, each side of the duct defining an inner wall of each respective chamber and the peripheral wall of the drum defining an outer wall of each chamber, a door associated with each respective chamber to enable filling or discharge of the crop into or from the chamber, said doors being located on the outer peripheral surface of the drum, the inner wall of each chamber comprising an inner perforate area located adjacent a corner portion of the duct to permit flow of air from the duct into the chamber to dry the crop therein and the outer wall of each chamber comprising an outer perforate area to permit discharge of moisture-laden air from the chamber to the surrounding atmosphere, and the inner perforate area leading the associated outer perforate area in the normal direction of rotation of the drum, flaps for controlling the air flow through the inner perforate areas, said flaps being located inside the duct adjacent the corner portions thereof, and means for operating the flaps during rotation of the drum.

Claim 17

Apparatus according to claim 14, wherein the means for rotating the drum is operative to rotate the drum at a speed of about 2 rev/min.

Claim 18

Apparatus according to claim 14, further comprising means for producing a flow of hot air through the duct, such that the air flow speed across the perforations of the inner perforate area is at least about 2,500 ft./min.