Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
63
Air Distributor
This invention relates to an improved air distributor
for distributing air uniformly along a longitudinal
plenum, particularly in a grain dryer.
It is frequently necessary to dry grain before it is
stored because a high moisture content may cause discolor-
ation and spoilage during storage.
Many systems have been developed over the years which
are intended to heat and dry grain uniformly while at the
same time avoiding the problems of stress cracking. One
such system is the cross-flow column type grain dryer in
which air is transversely forced through the downwardly
moving grain in an attempt to evaporate moisture. As
typical examples of cross-flow dryers there can be men-
tioned Markowich, U.S. Patent 2,732,630 and Fry, U.S.Patent 3,238,640. Such dryers typically have a plenum
for distributing hot drying air and one of the problems
of this type of dryer is that of trying to provide a
uniform air flow throughout the drying zone. As can be
seen from U.S. Patent 3,238,640, the plenum may be of
substantial length with heating air being introduced
from one end of the plenum. With this design it is very
difficult to have the drying air distributed throughout
the plenum such that there will be uniform pressures and
flow rates of air throughout the entire drying area.
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It is, therefore, an object of the ~resent invention
to provide a simple but effective distribution system which
will uniformly distribute drying air throughout the full
length of a longitudinal plenum.
Thus, the present invention in its broadest aspect
relates to an air distributor comprising a pair of spaced
side wall panels each tapering from a large end to a small
end and a plurality of air deflector vanes mounted across
between the side walls adjacent the tapered edges. These
vanes are contoured to deflect in an outward direction air
travelling longitudinally between the side walls.
The vanes are preferably arranged in opposed pairs and
because of the taper of the panel edges, it will be seen
that the spacing between the vanes of the opposed pairs
15 decreases along the length of the distributor.
The distributor system of this invention is open at
the top and bottom between the deflector vanes so that the
vanes in moving toward the centre line along the length
of the distributor have the effect of cutting successive
slices from a stream of air moving longitudinally through
the distributor. It is highly surprising that the air
which is allowed to pass between the vanes without deflec-
tion tends to continue on its longitudinal path such that
a very uniform distribution is achieved.
Certain preferred embodiments of the invention are
illustrated by the following drawings in which:
Figure 1 is a partial sectional view of a typical
grain dryer embodying the present invention;
Figure 2 is an isometric view of an embodiment of the
30 distributor of the present invention;
Figure 3 is a side elevation of the distribution and
Figure 4 is a top plan view of a plenum chamber of a
grain dryer containing the distributor.
The grain drying apparatus of the present invention is
35 generally illustrated in Figure 1 and is in the form of a
tower 10 supported by legs 11.
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Grain is introduced into the tower through a grain
inlet 12 and into a wet grain holding zone 13. This
holding zone is formed between outer solid panels 14 and
15 and inner solid panels 16 and 17. The grain is directed
from the holding zone 13 into a drying zone 18 formed
between inner and outer screen or mesh sections 19 and
20. These screen sections terminate in solid lower panels
21 and a solid divider panel 22. This divider panel 22
forms two outlets containing discharge metering rolls 24
driven by a variable speed drive unit 25.
The grain discharges into hopper 26 and is picked up
from there by vertical elevator tube 27 containing a grain
lifting auger 28. This lifts and discharges the grain into
an inner steeping zone 25 formed by the inner faces of the
lS panels 16 and 17 and lower inclined panels 30 and 31, which
in turn define an inlet to an inner drying zone 32. This
inner drying zone has outer and inner screen panels 33 and
34 respectively which terminate in lower solid panel sec-
tions and a divider panel forming two outlets containing
discharge metering rolls. These discharge into a dry grain
outlet 35.
Drying air for the drying columns 18 and 32 is supplied
through plenum 36 and the distributor 40 of the present
invention is mounted in an upper region of this plenum.
As will be seen from Figure 2, the distributor 40 has
a pair of tapering side walls 41 with tapering lower and
upper edges 42 and 43 respectively.
The distributor has a closed small end 44 and an open
air inlet large end 45. The large end also has vertical
mounting brackets 46 and horizontal mounting brackets 47
for mounting the distributor within a plenum. Correspond-
ing mounting brackets are provided at the small end.
Extending across between these side panels 41 immed-
iately adjacent the tapering edges 42 and 43, are series
of air deflector vanes 48.
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These vanes 48 are preferably substantially uniformly
spaced along the tapered edges and are preferably arranged
in opposed pairs. The vanes are also preferably of
circular contour, each forming a 90 arc of a circle.
The vanes 48 come closer and closer together along the
length of the distributor until the pair of vane9 at the
small end 44 are in contact with each other and are, in
fact, welded together.
As will best be seen from Figures 2 and 3, a column of
air enters through inlet 45 and in effect, slices are cut
from the top and bottom of this column by the first pair
of vanes 48, 49 and deflected upwardly and downwardly.
The column of air that remains continues to the second set
of vanes where a second pair of slices is cut off and
directed upwardly and downwardly and this continues along
the length of the distributor until the final remaining
thin column of air is totally distributed in two direc-
tions by the pair of touching vanes at the small end 44.
While the above description has shown an arrangement
20 particularly for use in a cross-flow grain dryer, it will
be seen that this distributor system can function equally
well either horizontally or vertically and can be used in
any kind of system where air must be uniformly distributed
through a plenum.
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