US2999676A

US2999676A - Grain conditioning apparatus

Info

Publication number: US2999676A
Application number: US817395A
Authority: US
Inventors: Ewell F Ewing
Original assignee: Individual
Current assignee: Individual
Priority date: 1959-06-01
Filing date: 1959-06-01
Publication date: 1961-09-12
Anticipated expiration: 1978-09-12

Description

Sept. 12, 1961 E. F. EWING 2,999,676

GRAIN CONDITIONING APPARATUS Filed June 1, 1959 PLENUM AIFZ CHAMBEQ A Z! M 13 24 INVENTOR.

2,999,676 GRAIN CONDITIONING APPARATUS Ewell F. Ewing, 133 S. th St., Beech Grove, Ind. Filed June 1, 1959, Ser. No. 817,395 3 Claims. (Cl. 263-19) This invention relates generally to grain conditioning apparatus and in particular to a means for introducing heat directly into the air stream flowing through a tube or housing with minimum heating of the central core area of the housing.

Grain, when harvested, normally has a moisture content considerably in excess of the optimum moisture content for suitable storage. The use of artificial heat drying of the grain in batch or continuous flow prior to placing the grain in storage has been widespread in conditioning grain. Another process used in drying grain has been the drying of the grain to the proper storage moisture content directly in the storage bin by adding supplemental heat to the air stream to thereby retain the required relative humidity of the air circulated through the grain independently of variations in relative humidity of the incoming air. Apparatus for this latter type of grain conditioning process has usually included an air moving fan and, positioned upstream of the fan, a heating means such as a gas burner or the like. The heating means is conventionally controlled by a fixed-setting humidistat located in the air chamber. In the past such apparatus has been characterized by the introduction of air heated by the burner at the central core area of the housing through which the conditioned air flows. Since the air stream inducing fan and its driving motor are customarily located in the housing with the axis of the fan and motor shaft coinciding with the axis of the housing, most of the air flow through the tubular housing occurs in an annular area adjacent the housing wall. Introduction of heated air at the central core area of the housing therefore results in something less than optimum mixing of the heated and unheated air and, further, tends to raise the temperature of the fan-driving motor to undesirably high levels.

It is a primary object of the present invention, therefore, to provide an apparatus for drying grain in storage in which supplemental heat, in the form of heated air, is added directly to the air stream so as to obtain a high degree of mixing of the heated air within the air stream without subjecting the fan motor to undesirably high temperature air.

A further object of the present invention is to provide an apparatus of the type referred to which requires a minimum of installation space.

A further object of the present invention is to provide an apparatus of the type referred to which includes a tub ular housing having an air stream-inducing fan and its drive motor mounted axially therein, and means for introducing heated air directly into the air stream while maintaining a minimum temperature rise of the motor and the housing walls.

The full nature of the invention will be understood from the accompanying drawings and the following description and claims:

FIG. 1 is a front view of an apparatus embodying the present invention.

FIG. 2 is a side view, partially in section, of the apparatus shown in FIG. 1.

Referring to the drawings, the apparatus includes a tubular housing member 10 having an open end 11. The opposite end of the tubular member is fitted with a flexible conduit 12 by means of a conventional hose clamp 13, the flexible conduit communicating with the plenum air chamber of a conventional, perforated floor type grain drying bin (not shown). Supported axially within the ice tube is a multi-bladed fan whose blades 14 extend from a hub 16 driven by an electric motor 17 supported by suitable brackets (not shown) within the tube. The rotation of the drying fan is such as to draw air through the open end of the tube and discharge it into the grain drying bin.

The marginal area of the tube 10 carries an outwardly flanged ring 18 whose peripheral flange is apertured to receive spaced studs 20. The studs extend rigidly from an annular member 19 and by means of spacers 20a and nuts 26b serve to rigidly mount member 19 upon the open end 11 of the tube and in spaced relation thereto. The member 19 is formed of sheet metal and rolled to form a generally annular tubular configuration which is spiral shaped in cross-section. The

marginal areas

22 and 23 of the member 19 overlap and are spaced from each other at the inner circumference of the heat exchange member, with the inner diameter of the marginal area 22 being equal to the inner diameter of the tubular housing 10. The spaced

marginal areas

22 and 23 thus provide an annular passage 24 which opens inwardly toward the end 11 of the tube 10, the marginal area 22 also providing a Vcnturi entry for the tube.

As may best be seen in FIG. 1, the member 19 is formed to provide a peripherally extending intake tube 26, an internal plate 27 serving to direct gases passing through the tube 26 in a controlled trajectory peripherally around the interior of the member 19. By means of a flanged connection 28 the tube 26 communicates with the interior of a burner assembly 29.

The burner assembly itself forms no part of the present invention and is not described in complete detail herein. As shown in FIG. 1, it may include a housing 31 having a gas burner 32 disposed therein. The gas burner may be monitored by a conventional thermocouple-operated pilot safety system indicated schematically at 33. The pilot burner 34 may be ignited through the grilled end 36 of the burner housing. A junction box 37 provides connection into the burner control valve energizing circuit for a conventional humidity responsive control or humidistat indicated generally at 38. The humidistat is preferably located in the plenum air chamber of the grain drying bin, indicated diagrammatically at 40 in FIG. 1, and responds to a predetermined increase in humidity of the air entering the grain drying bin to energize the control valve for the burner 32.

Adjacent the entrance to the tube 26 there is provided a booster fan indicated generally at 39 which may be electrically motor driven, the driving motor being energized whenever burner 32 is ignited. A conventional sail switch may be provided which is responsive to operation of the drying fan to assure that the burner 32 cannot be ignited unless the drying fan 17 is in operative condition. It will be understood that an air stream monitoring device other than a sail switch might, of course, be utilized to assure that the drying fan is operative before the burner is ignited.

In operation, the drying fan normally runs continuously, moving air through the tube 10 and into the grain drying bin. When the relative humidity of the incoming air is above, for example, 55%, the humidity responsive control 38 will cause the burner 32 to be ignited. The booster fan 39 serves to force the hot products of combustion into the heat exchange member 19 and move them in a controlled trajectory around the interior thereof. The hot gases within the heat exchange member exit through the annular passage 24 and enter the air stream in the tube 10 adjacent the outer peripheral margin thereof. With the fan and motor 17 mounted axially in the tubular housing the major portion of the air flow through the housing 10 occurs in a peripheral band adjacent the housing wall. The introduction of the high temperature gases through the passage 24 at this peripheral, maximum flow area, provides excellent mixing of the hot gases in the air stream. The introduction of the hot gases into the air stream is also selective in that the air entering the tubular housing at its central core area is left substantially free of hot gases, and this portion of the air stream, flowing past the motor 17 prevents an undesirable temperature rise of the motor. Spacing the member 19 outwardly from the end 11 of the housing permits the aspiration of unheated air through the space separating these elements as indicated by arrows in FIG. 2. This relatively cool air sweeps along the inner surface of the housing and prevents the housing walls from attaining an elevated temperature. Loss of heat by radiation from the housing is thus minimized and a safety factor is provided in preventing the occurrence of high temperature exterior surfaces on the apparatus.

When the relative humidity of the air entering the grain drying binis again reduced to a value below the control point, the burner 32 is shut down and the drying fan continues to operate, moving unheated air into the bin. When the relative humidity of the air entering the bin again reaches a value above the control point, the heating or humidity reducing cycle is repeated.

From the foregoing it will be evident that the trajec tory-type heater provided by the contour and placement of the member 19 results in the introduction of the hot gases into the air stream at a point such as to provide good mixing without subjecting the motor 17 to elevated air stream temperatures. The unheated air induced to flow through the space between the member 19 and the tube end 11 limits the temperature rise of the housing. The dimensioning of the inner diameter of the marginal area 22 so as to be at least equal to the inside diameter of the tubular housing 10 permits the hot gases to be introduced into the tubular housing without restricting the air flow therethrough and thus does not adversely afiect the capacity of the apparatus.

While the invention has been disclosed and described in some detail in the drawings and foregoing description, they are to be considered as illustrative and not restrictive in character, as modifications may readily suggest themselves to persons skilled in this art and within the broad scope of the invention, reference being had to the appended claims.

The invention claimed is:

1. Apparatus for introducing heated air into a grain storage bin comprising a cylindrical tube, a fan and an electric drive motor therefor mounted Within said tube coaxially therewith for moving air through the tube, the air outlet end of said tube being adapted to communicate with the grain storage bin, an annular tubular member having a generally spiral cross-sectional configuration in a plane parallel to the axis of said tube and supported on said tube in spaced relation with the air inlet end thereof, said annular member having spaced, overlapping marginal areas disposed at the inner circumference thereof, the diameter of said annular member at its inner circumference being at least equal to the inside diameter of said tube, said spaced marginal areas providing an annular passage communicating with the interior of said annular member, and means for introducing hot gases under positive pressure peripherally into said annular member, whereby the hot gases enter said tube only at the peripheral area thereof and unheated air is drawn into said tube through the space between said tube inlet end and said annular member thereby moderating the temperature rise of said tube and said drive motor.

2. Apparatus for introducing heated air into an enclosure comprising a tube, a fan and an electric drive motor therefor mounted within said tube coaxially therewith for moving air through the tube, the air outlet end of said tube'being adapted to communicate with said enclosure, an annular tubular member having a generally spiral cross-sectional configuration in a plane. parallel to the axis of said tube and supported in spaced relation with the air inlet end of said tube, said annular. member having spaced, overlapping marginal areas disposed at the inner circumference thereof, the diameter of said annular member at its inner circumference being at least equal to the inside diameter of said tube, said spaced marginal areas providing an annular passage communicating with the interior of said annular member, and means for introducing hot gases under positive pressure peripherally into said annular member, whereby the hot gases enter said tube only at the peripheral area thereof and unheated air is drawn into said tube through the space between said tube inlet end and said annular member thereby moderating the temperature rise of said tube and said drive motor.

3. Apparatus for introducing heated air into a grain storage bin comprising a tube, a fan and an electric drive motor therefor mounted within said tube coaxially therewith for moving air through the tube, the air outlet end of said tube being adapted to communicate with the grain storage bin, an annular tubular member having a generally spiral cross-sectional configuration in a plane parallel to the axis of said tube and supported adjacent the air inlet end of said tube, said annular member having spaced, overlapping marginal areas disposed at the inner circumference thereof, the diameter of said annular member at its inner circumference being at least equal to theinside diameter of said tube, said spaced marginal areas providing an annular passage cornmunicating with the interior of said annular member, and means for introducing hot gases under positive pressure peripherally into said annular member, whereby the hot gases enter said tube only at the. peripheral area thereof thereby moderating the temperature rise of. said drive motor.

UNITED STATES PATENTS References Cited in the file of this patent 591,966 Halliwell Oct. 19, 1897 2,477,584 De Zubay Aug. 2, 1949 2,815,982 Bleamaster Dec. 10, 1957 2,889,142 Ammann June 2, 1959