Note: Descriptions are shown in the official language in which they were submitted.
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TITLE OF THE lNV~NllON:
grain dryer
NAMES OF lNV~NlORS:
Mark George Daugela
Darcy John Daugela
FIELD OF THE lNV~NllON
The present invention relates to a grain dryer
BACKGROUND OF THE lNV~NLlON
Grain dryers generally include a housing with a plurality
of ducts. Grain is fed into the housing through an inlet at
or near a top of the housing and migrates by force of gravity
slowly down from the top to an outlet positioned at a bottom.
The ducts extend transversely across the path of the grain,
causing the grain to follow a path that weaves around the
ducts. Preheated air is blown into the housing through inflow
ducts and provided with a path to exit the housing via outflow
ducts. Exposure to the preheated air serves to dry the grain
as it migrates slowly through the housing from the inlet to the
outlet.
There are several ways to increase the processing capacity
of a grain dryer. A first way is to add additional levels of
ducts. An obvious problem with adding additional levels of
ducts is that it increases the size of the grain dryer. A size
will eventually be reached where the grain dryer is too large
to be transported along a highway. A second way to increase
the processing capacity of a grain dryer is to increase the
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volume of air that flows through the housing. A limitation on
increasing the volume of air is that eventually the force of
the air will be such that grain is blown out through the outlet
ducts. Where the force of the air causes considerable movement
of the grain, grain dust is released, which when combined with
oxygen in the air flow becomes a combustible mixture which
presents a serious fire hazard. A third way to increase the
processing capacity of a grain dryer is to increase the heat
exposure of the grain. The obvious limitation on increasing
heat exposure is that "excessive" heat exposure causes damage
to grain. It can adversely affect the living viable
germination ability of the grain. It can also mechanically
damage the grain. Kernels of grain tend to shrink when
moisture is removed. When the outside surface of the grain
shrinks and the moist center of the seed warms up, expansion
of the moist center of the seed may cause the outside surface
to split open. Once the kernel splits open, moulds, bacteria
and other pathogens are more readily able to attack the grain.
The heat exposure that the grain can withstand without being
damaged is a product of temperature and exposure time. The
higher the temperature the shorter the exposure time the grain
can withstand without damage occurring. A complicating factor
is the danger of uneven drying. It is preferable that all
seeds within the housing receive the same heat exposure. If
some seeds receive greater heat exposure and become
significantly drier than others, they will be more susceptible
to heat damage.
SUMMARY OF THE lNv~N-llON
What is required is a grain dryer with improved air flow.
According to the present invention there is provided a
grain dryer which includes a housing having a top and a bottom.
A grain inlet is positioned toward the top of the housing. A
grain outlet is positioned toward the bottom of the housing.
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A plurality of inverted "V" shaped air ducts defining an open
bottomed primary flow channel for at least one of ingress and
egress of air extend substantially horizontally into the
housing. The air ducts are configured in horizontally aligned
and vertically staggered rows such that kernels of grain are
exposed to a flow of air through the ducts as the kernels of
grain weave around the ducts in the process of migrating by
force of gravity from the inlet to the outlet. At least one
of the plurality of air ducts for the egress of air have a
defining wall with at least one secondary opening through the
defining wall. Air is able to pass through at least one
secondary opening in the defining walls to join egress air
exiting the housing via the primary flow channel, thereby
increasing egress air flow from the housing.
The grain dryer, as described above, can handle an
increased volume of air without blowing grain out through the
egress air ducts. It is of course preferred that a majority,
if not all of the egress air ducts, have at least one secondary
openings.
Although beneficial results may be obtained through the
use of the grain dryer, as described above, in order to ensure
that grain is not blown through the egress ducts it is
preferred that at least one cover member is provided over the
at least one secondary opening. The cover members prevent the
seepage of grain into the primary flow channel.
Although beneficial results may be obtained through the
use of the grain dryer, as described above, to obtain the
maximum benefit it is preferred that the defining walls are air
pervious. One manner of making the defining walls air pervious
is to provide a plurality of secondary openings. It is
preferred that each of the secondary openings has a louvre-like
cover member.
Although beneficial results may be obtained through the
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use of the grain dryer, as described above, even more
beneficial results may be obtained when a longitudinally
extending wall divides the flow channel into a first flow path
and a second flow path. This enables each duct to handle both
an inflow of warm air and an outflow of exhaust air, as
compared to the prior art in which separate ducts were used for
inflow and outflow. Substitution of a duct with a dividing
wall, as described, effectively doubles both the number inflow
ducts and the number of outflow ducts. This greatly enhances
the inflow of warm air, as warm air is entering at some many
more points. It also enhances the outflow of exhaust air, as
the exhaust air need not travel as far prior to an outflow
duct.
Although beneficial results may be obtained through the
use of the grain dryer, as described above, even more
beneficial results may be obtained when the first flow path and
the second flow path are not uniform. It is preferred that the
area of the first flow path decreases from the first end to the
second end. It is preferred that the area of the second flow
path increases from the first end to the second end. The first
flow path is positioned immediately adjacent to the defining
wall of the channel. When warm air is blown along the first
flow path, the convergence of the defining wall and the
dividing wall tends to force warm incoming air through the
openings in the defining wall. The increasing area of the
second flow path provides an unrestricted exit path for exhaust
air.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other features of the invention will become more
apparent from the following description in which reference is
made to the appended drawings, wherein:
FIGURE 1 is a perspective view of a first embodiment of
a duct constructed in accordance with the teaching of the
present invention.
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FIGURE 2 is an end elevation view of the duct illustrated
in FIGURE 1.
FIGURE 3 is a side elevation view, in section, of a grain
dryer having ducts as illustrated in FIGURE 1.
FIGURE 4 is an end elevation view, in section, of the
grain dryer illustrated in FIGURE 3.
FIGURE 5 is a perspective view of a second embodiment of
a duct constructed in accordance with the teachings of the
present invention.
FIGURE 6 is an end elevation view of the duct illustrated
in FIGURE 5.
FIGURE 7 is a side elevation view, in section, of a grain
dryer having ducts as illustrated in FIGURE 5.
FIGURE 8 is an end elevation view, in section, of the
grain dryer illustrated in FIGURE 7.
FIGURE 9 is a perspective view of a third embodiment of
a duct constructed in accordance with the teaching of the
present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Two preferred embodiments of ducts for a grain dryer will
now be described. A first embodiment of duct, generally
identified by reference numeral 10, will be described with
reference to FIGURES 1 through 4. A second embodiment of duct,
generally identified by reference numeral 100, will be
described with reference to FIGURES 5 through 8. A third
embodiment of duct, generally identified by reference numeral
200, will be described with reference to FIGURE 9.
Referring to FIGURE 1, duct 10 consists of an inverted ~V"
shaped open bottomed channel 12 having a defining wall 14 with
a plurality of openings 16 through which air passes. Referring
to FIGURE 2, it is preferred that openings 16 have fixed
louvre-like cover members 18.
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The use and operation of duct 10 in a grain dryer 20 will
now be described with reference to FIGURES 1 through 4.
Referring to FIGURES 3 and 4, grain dryer 20 includes a housing
22 having a top 24 and a bottom 26. A grain inlet 28 is
positioned at top 24 housing 22. A grain outlet 30 controlled
by a metering device 32 is positioned at bottom 26 of housing
22. A plurality of ducts 10 for the ingress and egress of air
extend substantially horizontally into housing 22. Referring
to FIGURE 3, each of ducts 10 has a first end 34 and a second
end 36. First end 34 of some of ducts 10 (designated lOa) are
in fluid communication with a central hot air plenum 37 and
receive an inflow of warm air from hot air plenum 37. Warm air
heated by a heater (not shown) is continuously blown into hot
air plenum 37 by a blower 39. Ducts lOa have second end 36
blocked. Second end 36 of some of ducts 10 (designated lOb)
are vented to the exterior to facilitate the escape of exhaust
air. Ducts lOb have first end 34 blocked. Referring to FIGURE
4, ducts 10 are arranged in rows 38 that are horizontally
aligned and vertically staggered. Kernels of grain 40 migrate
by force of gravity from grain inlet 28 to grain outlet 30.
In the process of such migration, kernels of grain 40 weave
around ducts 10 and are exposed to a flow of air through ducts
10 as indicated by arrows 42. With each of ducts lOa, warm air
from hot air plenum 37 rises through openings 16. With each
of ducts lOb, exhaust air enters channel 12 from both below
through the open portion of channel 12 and from above through
openings 16. This passage of air through openings 16 helps to
more evenly disperse the air flow throughout housing 22. Cover
members 18 help prevent blockage of openings 16 by migrating
kernels of grain 40.
Referring to FIGURE 5, duct 100 consists of an inverted
"V" shaped open bottomed channel 112, a first end 134, a second
end 136 and a perforated defining wall 114 that extends between
first end 134 and second 136. Defining wall 114 has a
plurality slotted perforations 116 through which air passes.
Referring to FIGURE 6, each of slotted perforations 116 has a
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fixed louvre-like cover member 118. Referring to FIGURE 5, a
longitudinally extending dividing wall 150 divides channel 112
into a first flow path 152 for warm air and a second flow path
154 for exhaust air. First flow path 152 is positioned
immediately adjacent to perforated defining wall 114. The area
of first flow path 152 progressively decreases from first end
134 to second end 136. Conversely, the area of second flow path
154 increases from the first end 134 to second end 136.
The use and operation of duct 100 in a grain dryer 120
will now be described with reference to FIGURES 7 and 8.
Referring to FIGURES 7 and 8, grain dryer 120 includes a
housing 122 having a top 124 and a bottom 126. A grain inlet
128 is positioned at top 124 housing 122. A grain outlet 130
controlled by a metering device 132 is positioned at bottom 126
of housing 122. A plurality of ducts 100 for the ingress and
egress of air extend substantially horizontally into housing
122. Referring to FIGURE 7, first end 134 of each of ducts 100
is in fluid communication with a hot air plenum 137 and receive
an inflow of warm air from hot air plenum 137. Second end 136
of each of ducts 100 are vented to the exterior of housing 122
to facilitate the escape of exhaust air. Referring to FIGURE
8, ducts 100 are arranged in rows 138 that are horizontally
aligned and vertically staggered. Kernels of grain 140 migrate
by force of gravity from grain inlet 128 to grain outlet 130.
In the process of such migration, kernels of grain 140 weave
around ducts 100 and are exposed to a flow of air through ducts
100 as indicated by arrows 142. Warm air from hot air plenum
137 flows along first flow path 152 until a convergence of
defining wall 114 and dividing wall 150 forces the warm air
through perforated slots 116. This passage of air through
perforated slots 116 helps to more evenly disperse air flow
throughout housing 122. Warm air then rises up through kernels
of grain 140 to the closest duct 100 to become exhaust.
Exhaust air passes along second flow path 154, with a
divergence of defining wall 114 and dividing wall 150 providing
an unrestricted path for the exit from housing 122 of exhaust
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air. As each of ducts 100 is both an inflow duct and an
outflow duct, warm air introduced into housing 122 travels a
shorter distance prior to being exhausted from housing 122.
This enables higher temperatures to be employed as exposure
time is less. Cover members 118 help prevent blockage of
perforated slots 116 by migrating kernels of grain 140.
Referring to FIGURE 9, third embodiment 200 iS illustrated
in order to demonstrate how first embodiment could be modified
lo to have but one secondary opening. As with the other
embodiments, duct 200 consists of an inverted "V" shaped open
bottomed channel 212 having a defining wall 214 that extends
between a first end 234 and a second end 236. Unlike the other
embodiments, however, defining wall 214 has but one secondary
opening 216 through which air passes. This single secondary
openings 216 iS covered by a fixed cover member 218. Third
embodiment 200, while workable, is not preferred.
It will be apparent to one skilled in the art that
modifications may be made to the illustrated embodiment without
departing from the spirit and scope of the invention as
hereinafter defined in the Claims.
