CROSS REFERENCE TO COPENDING APPLICATION
This application claims the benefit of U.S. Provisional application Ser. No. 60/021,587, filed Jul. 11, 1996.
TECHNICAL FIELD
The present invention relates broadly to the field of apparatus used for extracting moisture from granular materials. More narrowly, however, it deals with dryers which function to extract moisture from grain as a consequence of vaporization to the moisture resulting from heat transfer as the grain passes downwardly through a plenum or a series of plenum modules. A specific focus of the invention is a module which is insertable in an existing dryer to more efficiently effect the drying process.
BACKGROUND OF THE INVENTION
Various apparatus have been used for drying granular materials. Such apparatus are particularly useful in treating grains such as oats, rapeseed and soybeans. Moisture is removed to process a valuable foodstuff and to maximize the period of time over which the grain can be stored.
Proper processing is facilitated in other ways also. The objectives previously discussed can also be obtained, in some measure, by thermal treatment of the grain.
Depending upon the particular grain, a number of effects can be achieved. Moisture removal and heat treatment can have the effect of deactivating fat-reducing enzymes. This results in lengthening the storability of the grain. In some cases, the treatment results in the removal of bitter tastes and brings out, more effectively, pleasing flavor and aroma.
Grains, when properly treated, are heated generally evenly over a desired period of time. The time over which heating occurs is dependent upon capacity of the treating apparatus and other factors. Heating can be maintained, if desired, for several hours by regulating the rate of flow of the grain through a treating apparatus. Product temperatures can be elevated up to approximately 130° C.
One apparatus used for drying, for example, oats has been developed by Buhler-Miag. The apparatus design employs a plurality of modules stacked vertically to define a vertically-elongated processing plenum. The grain is introduced in the uppermost module, and it passes downwardly, through a plenum formed by the stacked modules, to an egress aperture controlled by appropriate apparatus. Introduction of grain into the apparatus, proximate the top end thereof, is coordinated with discharge of the grain from the bottom so that the device is maintained in a substantially full disposition at all times.
The grain moves through the various modules as it passes downwardly through the column of interconnected modules. The time to which the grain is exposed to thermic treatment is governed by a number of factors, including the volume of grain in the apparatus and the flow rate of the product downwardly.
Each module employs a plurality of rows of staggered closed ducts extending across the modules. Staggering of the ducts in adjacent rows facilitates an even heating of the grain. The ducts are closed in cross-section, and the ducts convey steam from an inlet manifold on one side of the module to an outlet manifold on the other side of the module. One type of duct employed in the Buhler-Miag dryer is generally hexagonal in cross-section and of a generally vertically elongated configuration.
The Buhler-Miag dryer varies from other prior art devices with regard to the extent of moisture removed from the grain. Typical, however, of devices of this type known in the prior art is a removal of 0.1-0.2% of the moisture as the temperature of the grain is elevated from between 50° F.-150° F.
It is to these dictates of the prior art and the shortcomings thereof as discussed above that the present invention is directed. It is an improved structure, usable in combination with, for example, a Buhler-Miag dryer to increase the efficiency thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective illustration of a drying column employing modules, as known in the prior art, and a module in accordance with the present invention;
FIG. 2 is a side elevational view of the drying column of FIG. 1, some portions thereof being broken away;
FIG. 3 is a top plan view of the drying column of FIG. 1, some portions thereof being broken away;
FIG. 4 is an enlarged view of structure circled at “4” in FIG. 2 illustrating means for maintaining adjacent modules securely connected one to another, as known in the prior art;
FIG. 5 is a cross-sectional view of a steam duct, as known in the prior art; and
FIG. 6 is a cross-sectional view illustrating a steam-conducting conduit employed in the module in accordance with the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to the drawings wherein like reference numerals denote like elements through the several views, FIGS. 1,
2, and
3 illustrate a
grain drying column 10 employing the present invention. The
column 10 employs a plurality of
modules 12, as known in the prior art, which define a
plenum 14 through which
grain 16 passes vertically downwardly through the
column 10. Also included (shown third from the bottom in FIG. 2) is a
special module 18 in accordance with the present invention as will be discussed hereinafter. The
modules 12,
18 can vary in their vertical dimension, but a typical vertical dimension for a module is on the order of approximately three feet. Since the
column 10 illustrated in FIGS. 1 and 2 includes eight total modules, its vertical height would be on the order of twenty-four feet plus the vertical dimension of each of an ingress truncated
pyramid section 20 at the top of the
column 10, a
rotary valve section 22 below the treating modules, and an inverted egress, truncated
pyramid section 24 at the bottom of the
column 10. It is not uncommon for the total vertical dimension of the
column 10 to be on the order of approximately thirty feet.
As previously discussed, the
column 10 includes a generally truncated
pyramidal section 20 at the top of the
column 10 which functions to receive grain from a feed source (not shown). The
grain 16 is deposited through an
aperture 26 at the top of the
pyramidal section 20 and, eventually, fills the
plenum 14 defined by the mated modules. The bottom of the
plenum 14 is defined by a floor comprising one or more
rotary valves 28 which can be operated to afford egress to the
grain 16 after it has been processed in the
plenum 14. FIG. 2 illustrates seven
separate rotary valves 28 at the bottom of the
plenum 14.
After
grain 16 has been passed through the
rotary valves 28 in a selective fashion, it is deposited into the inverted egress
pyramidal section 24. It can, thereafter, be transferred by appropriate conveying structure (not shown) to a storage site.
A sensor (not shown) can be provided in the ingress
pyramidal section 20 in order to measure the location of the upper surface of
grain 16 within the processing apparatus. The sensor can, in turn, be coordinated with the
rotary valves 28 in order to maintain the
grain 16 at a desired level. That is, if the level drops too low, the rotary valve operation will be slowed down so that the level of the
grain 16 at the top of the
column 10 can be elevated. Conversely, if the level of
grain 16 becomes too high, rotary valve operation can be maintained more constant until the level of grain drops.
The drying and
heating modules 12 known in the prior art include a plurality of rows of
ducts 30, as best illustrated in FIG.
2. As seen in FIG. 5, each of these
ducts 30 can be a closed hexagonal cross-sectioned tube through which steam can be conducted. The steam is heated to a temperature so that, as it is passed through each
duct 30, from an
inlet manifold 29, through the
duct 30, into an
outlet manifold 31, and through
exit tubes 33, it will elevate the temperature of the
grain 16 to a level at which drying and thermic treatment will be facilitated.
The prior
art treating modules 12 illustrated in FIG. 2 show arrangement of the
ducts 30 wherein
ducts 30 in one row are staggered from
ducts 30 in an adjacent row. This staggering enables facilitation of heating of the
grain 16, since virtually all of the
grain 16 will engage
multiple ducts 30. Further, each duct typically has a width of approximately one inch and a vertical height of approximately three inches. Such dimensioning is coordinated with the spacing between
adjacent ducts 30 in one row and the location of ducts in an adjacent row to further facilitate maximization of heat transfer.
FIG. 4 illustrates a manner of mating adjacent modules. Each module is defined by a vertical encircling wall, and upper and lower ends of this wall are provided with
flanges 32 which, when the modules are properly positioned relative to one another, abut with cooperating flanges of adjacent modules. A
seal 34 is inserted between the
flanges 32 prior to the time that they are brought into engagement, and the
flanges 32 and interposed
seal 34 are provided with registered apertures for receiving the shank of a
bolt 36. A
nut 38 is secured to a distal end of the
bolt 36, after it has been passed through corresponding registered apertures, to hold one module in tight engagement with another.
FIG. 6 best illustrates the construction of
channels 40 disposed within the special processing module
18 (that is, the third from the bottom module viewed in FIG.
2). These
channels 40 have a construction and orientation similar to the
ducts 30 of the prior art modules
12 (that is, as seen in the figures, generally transverse to a direction of passage of particulate material through plenum
14), but the bottom of each
such channel 40 is open. As heated air is introduced into the
plenum 14 proximate upper and lower ends thereof, it will, as it passes downwardly through the plenum from the upper end and upwardly through the plenum from the lower end seep into
channels 40 as it passes through the treating column, and, specifically, through the
special module 18. As the heated air passes through the
grain 16 in vertically traversing the treating column, it will absorb moisture from, and dry, the
grain 16.
A
suction mechanism 62 downflow of the drying apparatus, facilitates passage of the treating heated air through an
outlet aperture 42 in a
wall 44 of the
special processing module 18 and into an outlet manifold
68. Thereafter, the heated air will be processed in a manner as will be discussed hereinafter.
Passage of the heated air into, and through,
channels 40 will be facilitated because of the suction mechanism downflow of the drying apparatus. Such passage of the heated air will not be occluded through
channels 40 in view of the fact that the
grain 16 passing through the
plenum 14 is passing downwardly. The expected profile of grain flow around
channels 40 is best seen in FIG.
6. The heated air passing through the
grain 16 into the
channels 40 and through
apertures 42 into outlet manifold
68 will effectively accomplish drying.
FIG. 1 illustrates a heated air conduction system for use in combination with the treating column. Illustrated is a
hot air plenum 48 which is down-flow from a
blower 50 having a
fan 52 mechanism. Heated air fed into the
plenum 14 by the
blower 50 is, thereafter, passed through a
reducer manifold 54 and into upper and
lower feed legs 56,
58 which conduct the heated air to manifolds
57,
60 proximate the top and bottom, respectively, of the
column 10. Heated air is fed directly into the
plenum 14 by the
upper feed leg 56 for passage into
manifold 57 and introduction into
grain 16 through
channels 59 extending across
ingress section 20, and, thereafter, downwardly through the
grain 16 in the direction of movement of the
grain 16 through the
plenum 14. Additional inlet manifolds
57 connected at various points along the
column 10 may be included. The
lower feed leg 58 feeds a manifold
60 for injection of the heated air proximate the lower end of the
column 10 and passage in a counter-current direction to the flow of the grain. Heated air thus passing through the
plenum 14 is sucked out of the
plenum 14 through the
special module 18, via
channels 40, and into a
cyclone 62 where particulate material is removed through a controlled
rotary valve 64.
The figures also illustrate inlet and outlet manifolds for each of the prior art modules. These, of course, as discussed hereinbefore, are operated in the same manner as they are in the prior art. That is, heated steam is fed to the inlet manifolds
29 from where it passes through the
ducts 30 to the respective outlet manifolds
31. Thereafter, it is reprocessed for subsequent use.
By employment of the
special module 18 as described herein, it has been found that efficiency of the dryer can be improved significantly. Where, as previously discussed, prior art dryers remove 0.1-0.2% of the moisture in the column, it is estimated that drying in the range of 1% to 3% should be able to be achieved for many grain or oilseed products when an apparatus modified by employment of the special module described herein is utilized.
It will be understood that this disclosure, in many respects, is only illustrative. Changes may be made in details, particularly in matters of shape, size, material, and arrangement of parts without exceeding the scope of the invention.