~ 6,Z4~6 BACKGROUND OF THE INVENTION
This invention relates to an improved continuous grain flow, concur-.
rent-countercurrent type grain dryer.
Grain, particularly corn, is often dried after picking and before storage to prevent wet pockets, mildew and consequent spoilage. Fast, efficient drying may be effected by the introduction of a generally heated, ~ .
low moisture content drying medium (usually air) to the wet grain. The drying medium is moved relative to the grain and accumulates moisture from ~ -. . .
the grain. The moist saturated drying medium is then removed from contact 10 with the grain with the result that the grain has a relatively lower moisture k '' '"", ;.
~i~ Various types of grain dryers have been disclosed by the prior art. -; ~
. . :- : : .
1~ For example, Meiners et al in Canadian Patent No. 950, 660 discloses a con- ;
i~ : : :'.. :' ¦ ~ current-countercurrent grain dryer including a preheater means. Grain i9 i' .`, ,~,:
introduced to the top of a bin and removed from the bottom in a continuous .,', ;, process. Cold air is introduced through cold air inlets adjacent the bottom of the bin for countercurrent flow. Hot dry air is introduced adjacent the top of the bin for concurrent flow. Both flows are removed at an intermediate position within the bin through exhaust ducts. An additional set of preheater ~-ducts which ser~e an exhaust function are positioned above the hot air inlet ~. ;
j~ ducts. !,,','~
While such a grain drying mechanism provides adequate results, additional research and experimentation has shown that the exhaust air dis-1~ charged from the grain dryer is often not fully moisture laden, nor is the ~, ': :
temperature adequately reduced to achieve maximum efficiency by the dryer. , ;
: i', :' .,, To improve the eficiency of moisture and heat transfer between the drying :,!" '' ,'' medium (air) and the material being dried (grain), is a desirable objective `
in a grain drying system. Maintenance of the concurrent-countercurrent method of drymg the grain is also de=lrable in order to maxlmize grain ~J~
` ~l06;~;6 SUMMARY OF THE IN~ENTION ~.
In a principal aspect, the present invention comprises a grain dryer of the concurrent-countercurrent continuous ~. :
grain flow type including at least two sets of hot air inlet -.
ducts connected to a single hot air inlet manifold and at .. .
least one set of cold air inlet ducts connected to a cold air inlet manifold. Additionally, at least two separate sets of exhaust ducts are included. One of the sets of exhaust ducts is .
connected to the hot air inlet manifold to provide for recycling : .
of exhaust air, while the other set of exhaust ducts discharge .. :
moisture laden air to the atmosphere. .:.
It is thus an object of the present invention to - . .
provide an improved continuous grain flow, concurrent-counter~
current grain dr~er. ~.
~nother object of the present i.nvention is to provide .
a grain dryer of the concurrent-countercurrent type wherein .
exhuast air from the dryer is recycled in order to increase ..
Still anoth.er object of the preaent invention is to ..
provide an i~proved concurrent-countercurrent continuous gxain .
flow dryer of simplified construction.
Thus, in accordance with the i.nYention, th.ere is provided, i.n a conti.nuous ~low grain dr~er ~f the type having ~.;
an enclosed bin ~i.th a wet grain inlet at the top o~ the bin, grai.n outlets at th.e bottom o~ thb bin, meana ~or providing wet grain at the inlet, means for remoYing grain at the outlets, the improved concurrent counterflow structure for drying said . .
gra;.n comprising, in combination: a lower set of horizontal :~
cold air inlet ducts extending the length o~ sai.d bi.n and joined to means for di.recti.ng cold air into said cold ai.r inlet ducts; a first transverse set of horizontal exhaust ducts above `~
the cold ai.r ducts and transverse thereto, said first exhaust ~ :
-2- ~ :
~2456 . ;..~;; -.:
ducts connected to a hot air manifold; a first set of horizontal ;. ~-hot air inlet ducts parallel to the lower set of cold air .~.
inlet ducts and positioned above the first exhaust ducts, said.. . ::.
first set of hot air ducts also connected to the hot air mani-r,;',.... ;
fold; a second set of horizontal exhaust ducts above the first set of hot air inlet ducts and transverse thereto, said second set providing exhaust from the bin to the atmosphere; a second... ;~
set of horizontal hot air inlet ducts parallel to the lower cold air inlet ducts and positioned abo~e the second exhaust ducts, said second hot air inlet ducts also connected to the ~
hot air manifold; and means for providing hot air flow to .
the hot air manifold for subsequent ~low into said hot air .:.:.:.
inlet ducts whereby, air from said fîrst set of exhaust ducts .
is combined with the hot air inlet flow to said hot air inlet ducts. ~
The above and other objects, advantages and features ' of the invention will be set forth in the detailed description which follows: ~
BRIEF DESCRIPTION OF: THE: DRA~ING ~.:
In the~detai.led description ~hich. follows, reference ,:
, will be made to the drawing compri.sed of the following figures~
~: FIGURE 1 is a cut-away perspective view of the improved .... :
grain dryer of the present invention; ,~ ..... `
FIGURE 2 ig a cross-sectional end Yie~ o~ the grain ~ :
dryer taken th.rough the plenum chambers along the line 2--2 in ;, FIGURE l; and , ;
FIGURE 3 is a cross-sectional end view taken along the line 3--3 in FIGURE 1. . : ~
DESCRIPTION OF THE PREFERRED EMBODIMENT ~.... .
Referring to the figures, like num~ers refer to like parts. The grain :
~ -2a-~62~56 dryer includes a grain bin 10 which includes opposed side walls 12 and 14, a top wall 20 and inclined bottom walls 22 and 24. A grain feed auger 26 is provided to feed wet grain into the top of the bin 10. A diverting plate 28 spreads the grain over the interior of the bin 10 as it is being fed into the bin 10 by the auger 26. Grain is introduced to the auger feed 26 through a hopper 30 as shown or through auger means, not shown. Grain is continuously intro- `
duced into the bin 10. During operation of the bin 10 as a dryer, the bin is substantially filled with grain as it is continuously fed into the top of the bin 10 and withdrawn from the botto~
The inclined bottom walls 22 and 24 are arranged at substantially the angle of repose of grain fed into the bin 10. A discharge auger 32 con- `
tinuously removes dried grain from the bin 10. A grain floor construction (described below) is positioned above the auger 32. Thus, grain from the bin 10 passes through the floor construction and flows to the auger 32 for removal. ~' The grain continuously passes downwardly through the bin 10.
Simultaneously, various flows of a drying medium, preferably air, also flow through the bin 10. The general flow of the drying medium and similar dryer constructions have been generally described in various prior art patents, including Meiners et al Canadian Patent No. 9~0, 6.60. The structure of the 20 present invention retains some of the characteristics associated with the prior art and additionally provides for a new combination o air flow in response to a new grain dryer structure. The general concurrent-counter- ;~
current air flow is preserved with the structure of the present invention. ~-Referring again to the figures, a cold air manifold 33 comprised of manifold walls 34-39 includes a cold air inlet 40. The cold air inlet 40 ,~ is, in the construction shown, provided in wall 37. A fan 42 is mounted in ~;
wall 35 to draw air through inlet 40 into the cold air manifold 33 and through `
opening 44 into a cold air plemlm 46. Plenum 46 is defined by end wall 18, ;~
side walls 12 and 14, bottom walls 22 and 24, a top wall 50 and manifold -30 wall 35.
A plurality of cold air inlet ducts 52 connect with the plenum 46 so :
that cold air may pass into the inlet ducts 52. The cold air inlet ducts 5Z are ; -; .
triangular in cross-section and form part of the grain bin floor in the same .:. :.:~, manner as disclosed in Canadian Patent No. 950, 660, which is incorporated . :.
herewith by reference. Thus, the cold air inlet ducts 52 comprise a plurality `.
of horizontal, parallel inlet ducts S2 which are perforated so that cold air canflow from the interior of the ducts 52 to the interior of the bin 10. The ducts 52 are spaced from each other to define parallel openings through which the grain passes subsequent to drying. Rotating metering rolls 54 serve to dis~
charge the grain through these parallel openings onto the bottom wall or floor .
22 and 24 of the bin 10 for removal by means of auger 32.
Immediately above and transverse to the cold air inlet ducts 52, are . .
parallel spaced, diamond cross-section exhaust ducts 56. The exhaust ducts .:
56 are formed from perforated material in the same manner as exhaust . ;
ducts disclosed in Patent No. 950, 660. The exhaust ducts 56 terminate at opposite side walls 12 and 14. In combination with side walls 12 and 14, ' : .
there is provided an exhaust manifold 58 which includes outer wall 60, upper ~.
wall 62, extensions of the end walls 16 and a bottom wall 62. The plenum 58 connects with a hot air mlet manifold 64 formed by a vertical extension f wall 35, wall 34, wall 37, side walls 38 and 39 and a top wall 66. Thus, . .
e~aust air from the exhaust ducts 56 passes from plenum 58 into hot air manifold 64. ;:
Positioned above the exhaust ducts 56 and arranged in like fashion is a second set of exhaust ducts 68 which also exit into the exhaust manifold 58.
Again, exhaust products through ducts 68 ultimately flow into n~anifold 64.
Positioned above the exhaust ducts 68 is a first set of hot air inlet .
"~ ' . .
ducts 70, The hot air inlet ducts 70 are arranged in parallel with the cold air inlet ducts 52. Ducts 70 have a construction of the type shown in Patent :
No. 950, 660. As shown in the drawing, the ducts 70 terminate in a plenum 72 :
,. '," ' .
4- ~ . .
- which includes its own burner 74 for heating air coming into the plenum 72.
A hot air inlet fan 76 moves air from manifold 64 through opening 78 into plenum 72 where it is heated and discharged into the ducts 70.
Within bin 10 and above the hot air inlet ducts 70 is another set of . , .
exhaust ducts 80. Exhaust ducts 80 are parallel to the previously described ~; exhaust ducts 56 and of similar construction. Exhaust ducts 80 terminate through side walls 12 and 14 and exhaust to the atmosphere.
A final set of hot air inlet ducts 82 are positioned above the exhaust ducts 80. Hot air inlet ducts 82 connect with plenum 86 which is separate ;i~, 10 from plenum 72 and which includes a separate burner 88. Thus, air from ~; manifold 64 is moved by a fan 90 through opening 92 into plenum 86 for heating ~,:........................................................................ .
`, by burner 88 and discharge into hot air inlet ducts 82. Ducts 82 are parallel -.' ~
~ to ducts 70 and of similar construction.
; A final set of transverse exhaust ducts 94 are arranged above inlet :.;.
~ ~ ducts 82. Ducts 94 also exit to the atmosphere and permit air flow upward ~:~
to effect preheating of the grain entering the main section of the grain dryer.
~- The various air fIows are as illustxated in FIGURE 1. That is, cold !~ air enters the cold air inlet or grill 40 passes through the cold air plenum 33 and manifold 46 into the cold air inlet ducts 52 for countercurrent flow upward 20 through bin 10. This cold air is partially exhausted through ducts 56. The ~i exhaust air is recycled or redirected through manifold 64 and plenums 72 and 86 into hot air inlet ducts 70 and 82.
Air is provided in manifold 64 from exhaust ducts 56 and 68. Supple- -mental air is provided through an inlet grill 93. This air is mixed. Part o the air passes into the plenum 72 and part of the air passes into plenum 86.
Air in plenums 72 and 86 respectively passes into ducts 70 a;nd 82 respectively.
This hot air then assumes a generally concurrent flow. Air from inlet ducts 70 exhausts, at least in part, through exhaust duct 68. Air from inlet duct 82 `
exhausts through duct 80. Part of the air from inlet duct 8Z also passes ' ~6zg~5~
through exhaust ducts 94, thereby serving to preheat a portion of the grain ~` flowing through bin 10. This preheat function is eimilar to that described in Canadian Patent No. 950, 660. ~ I
Hot air flow is generally concurrent and cold air flow is generally countercurrent to the flow of grain through the bin 10. Additionally, a portion of the air passing through the bin is recycled therethrough to improve efficiency of operation of the grain dryer. Note that it may be possible to eliminate one of the sets of exhaust ducts such as exhaust ducts 56. Elimination of such ducts would not eliminate the function of recycling of air thraugh the grain dryer. Importantly, the construction of the present invention permits re-cycling of air in a continuous grain flow type grain dryer to thereby improve c ., , ~
the efficiency of operation of the dryer.
i While in the foregoing there has been set forth a preferred embodi-;ij~ ment of the present invention, it is to be understood that the subject matter , .
of the invention will be limited only by the following claims and their equiv-i alents.
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