Note: Descriptions are shown in the official language in which they were submitted.
21955~~
Docket 58050
TANGENTIAIr SEPARATOR
FIEhD OF THE INVENTION
The present invention relates to air
separators and more particularly to an improved method
and apparatus for separating and accumulating airborne
material.
BACRGROOND OF THE INVENTION
A wide variety of separators have been
developed that separate and accumulate various objects
transported by an air stream, such as paper waste, scrap
material, food items, or other products. These
separators utilize various configurations which are
designed to receive a high velocity stream of air
transporting prescribed objects, and subsequently
separate the objects from the conveying air. The objects
are typically accumulated at or near a designated exit,
while the air or other transport gas is directed to a
second exit. A problem associated with many separating
systems, and particularly in separating systems design
for the collection of scrap paper, is that they typically
generate a large amount of dust and/or other air-borne
contaminants proximate the material exit.
One type of separator that has been extensively
used is a cyclone separator wherein the transported
objects and a stream of air are introduced into a large
cylindrical or cone-shaped device. The transported
objects are introduced into the cylindrical housing so
that they are thrust against the outer wall by
centrifugal forces resulting from the flow of the air
stream within the cylinder. The air exits via the top of
the cylindrical device while the objects are typically
funneled out a bottom exit. Cyclone separators are
generally very large and somewhat expensive pieces of
mechanical equipment. Cyclone type separators are often
so large that it is not feasible to install them inside a
building. Consequently, most cyclone type separators are
2~ 955 2
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typically situated outside the building and often on the
roof of the building. Reducing the dust in these
exterior cyclone separators has not been of great concern
because the presence of dust outside a building typically
does not adversely affect people or equipment.
A prior art cyclone separator system that is
concerned with the separation of dust from the
transported objects is disclosed in United States Patent
No. 3,116,238 issued to Van Etten. The '238 patent
discloses a modified cyclone type separator that includes
the standard central air discharge funnel directing the
air from the cyclone separator. It also includes a
screen disposed along the outer wall of the separator to
facilitate the separation of removal dust and fine
particles from the stream of air and conveyed material.
While this device attempts to address the problem caused
by dust associated with the separating action, there
remain several other problems associated with this
patented device. Namely, it is still a very large
device, and the air maintained within the housing is
maintained at a high velocity and thus a relatively high
static pressure.
Another type of separator is a tangential
separator where the transported objects are recovered on
a flat or cylindrical screen and the air which passes
through the screen exits the separator in a generally
tangential orientation. Tangential separators are
typically smaller devices than the cyclone separators and
thus are often installed within the confines of a
building or factory. For this reason, the air exiting
the tangential separator is typically reintroduced into
the interior environment of the building or is reused
within the air conveying system. In either situation, it
becomes increasingly important to filter the exiting air
prior to its reuse and to minimize the dust and other
contaminants introduced into the environment near the
material exit.
2~~~5~2
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Most applications in which tangential air
separators are used can be classified either as a
positive ("push type") system, a draw through ("pull
type") system, or a hybrid system. As the classification
suggests, draw through or "pull type" systems are those
in which the air stream and transported objects are
pulled into the separator with a fan located downstream
of the separator. In such draw through systems, the
separator is typically maintained below atmospheric
pressure and typically requires an air lock to prevent
any back flow of air from the object discharge exit.
Positive or "push type" systems, on the other hand,
include systems where the air and conveyed objects are
blown into the separator with the fan located upstream of
the separator. In push type systems, the pressure within
the separator is above standard atmospheric pressure.
The hybrid systems involve both "pushing" as well as
"pulling" of the conveying air stream such that an ideal
pressure is maintained within the separator.
Clearly, the static pressure within the
tangential separator is an important design
consideration. Consider for the moment, a push type
paper conveying and separation system where the paper
material exits the separator and falls to a baler or
compactor. If the static pressure at the material exit.
of the separator unit is too high, dust and paper scraps
tend to swirl around the material exit resulting in a
somewhat untidy and very dusty environment proximate the
material exit. However, if the static pressure at the
air and material inlet in the separator unit is too low,
the result is an inefficient conveying system susceptible
to clogging.
Pull type systems and hybrid type systems
alleviate some of the aforementioned static pressure
concerns but are generally more complex and more
expensive systems. Moreover, the push type tangential
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separator systems are often the simplest to design, and
are easy to install and maintain.
One related art tangential air separator is
disclosed in United States Patent No. 4,900,345 issued to
Le Jeune which discloses the use of a deformed
cylindrical grid in a tangential separator which allows
most of the air flow to exit tangentially through the
separator. The remainder of the air together with the
transported objects presumably exit through a central
exit portion of the separator via the spiral nature of
the deformed cylindrical grid.
Another related art tangential separator system
is disclosed in United States Patent No. 4,300,926 issued
to Brooks which discloses a separation apparatus adapted
to receive a stream of airborne material and which
includes a single rear exit screen and a bottom material
exit. An adjustable baffle is located near the separator
inlet directing the incoming stream to the rear exit
screen which allows the air to exit tangentially while
the material continues to be transported through
separator. The separator is designed with an increasing
cross-sectional area for decelerating the transported
material as it moves through the duct.
Still another related art system is disclosed
in United States Patent No. 4,484,843 issued to McGlinsky
et al. which shows a multi-chamber pneumatic conveying
scrap paper system that also utilizes a flat rear exit
screen for passing air and dust while the paper is
directed and/or falls downward to a gathering hopper.
While these related art systems may adequately
separate the transported material from the air stream,
there remains a need to provide an improved tangential
separator that is relatively small device, yet simple to
install, operate and maintain and more importantly
facilitates the relatively clean discharge of material.
2~~55~~
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SOMMARY OF THE INVENTION
The present separating apparatus is a
tangential air separator for separating material
transported by air or other transport gases and includes
a casing having a tangential inlet adapted to receive a
stream of air and material and a plurality of exits. The
casing of separator assembly includes a perforated outer
wall proximate the inlet which functions as a means for
peripherally removing a portion of air from the stream of
air and material received at the inlet. An important
advantage offered by the perforated outer wall is that it
decreases the velocity of the stream of air transporting
the material and also reduces the static pressure within
the separator casing. A second air separation device is
disposed in the interior of the casing and is adapted to
further separate the air from the material entrained
therein, leaving mostly the transported material.
Two separate and distinct air exits are
provided including a first air exhaust conduit
peripherally attached to the casing and operatively
associated with the peripheral means for removing an
initial portion of air and a second air exhaust conduit
operatively associated with the interior means for
separating air. Another exit on the separator apparatus
is the material discharge exit which, like the inlet, is
peripherally attached to the casing. Because of the
multiple air exits, the static pressure remains
relatively low at the material discharge exit. Thus
there are no significant problems associated with
swirling dust and other particles near the collection
site.
In one aspect of the invention, the casing is a
generally cylindrical shaped casing with an air and
material inlet being tangentially oriented near the top
of the casing. The material discharge exit or outlet is
preferably located at the bottom of the casing so as to
allow the material to exit out of the separator after
2~955~~2
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much of the air has been removed. The peripheral air
removal means is a perforated arcuate surface which
advantageously improves the flow of air and material
within the casing. The interior air exit means is a
perforated cylinder concentrically disposed in the
cylindrical shaped casing. The second air exhaust
conduit can be tailored to provide bi-directional flow of
the exit air out of each side of the cylindrical shaped
casing or may alternatively retain the conventional uni-
directional flow out of one side of the casing.
In another aspect of the invention, the two air
exits of the separator apparatus can be combined
and directed to a single air outlet. The air discharged
from the single air outlet can be returned to its point
of origin to be re-used for conveying additional
material. In addition, an appropriate filtering means
can be incorporated within the air outlet such that the
removed and separated air can be safely recycled and/or
re-introduced into the immediate environment. Further,
since the present tangential separator apparatus is
relatively small in size as compared with cyclone type
separators, it is particularly suitable for use inside a
building.
The invention may also be characterized as a
method for separating material transported by air which
comprises the steps of: (a) receiving a stream of air and
material at an inlet of a casing, the inlet being
disposed at the periphery of the casing; (b) removing a
portion of air from the stream of air and material via a
peripheral air exit proximate the inlet in order to
decrease the velocity of the stream of air transporting
the material and reduce the static pressure within the
casing; (c) directing the removed portion of air via a
first exhaust conduit to an air outlet located apart from
the casing; (d) further separating air from the material
within the interior of the casing;(e) transporting the
separated air out of the casing via a second exhaust
219552
conduit; and (f) discharging the material remaining in
the casing via a material outlet, the material outlet
being located at the periphery of the casing and apart
from the inlet.
The present method and apparatus for separating
airborne material realizes the aforementioned features
and advantages in a manner that is clearly evident from a
thorough consideration of the detailed description when
taken in conjunction with the drawings wherein there is
shown and described illustrative embodiments of the
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
In the following detailed description,
reference will be made to the attached drawings in which:
FIG. 1 is a perspective view of a tangential
separator system for separating and accumulating airborne
material, such as paper scrap, embodying various features
of the present invention;
FIG. 2 is a side elevational plan view of the
separator apparatus illustrated in FIG. 1 with one air
exhaust conduit removed;
FIG. 3 is a front plan view of the separator
apparatus illustrated in FIG. 1;
FIG. 4 is cross-sectional side view of the
separator apparatus illustrated in FIG. 1 taken generally
along line 4-4 of FIG. 3;
FIG. 5 is a cross-sectional view taken along
line 5-5 of FIG. 2 illustrating the perforated outer wall
of the separator apparatus;
FIG. 6 is an elevational view of the interior
perforated cylinder used for separating the air from the
material present within the separating chamber;
FIG. 7 is a side view of an alternative
embodiment of a separator apparatus embodying various
features of the invention;
CA 02195512 2005-O1-07
_8_
FIG. 8 is a front view of the separator
apparatus illustrated in FIG. 7; and
FIG. 9 is a top view of the separator apparatus
illustrated in FIG. 7.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The following description includes the best
mode presently contemplated for carrying out the
invention. This description is not to be taken in a
limiting sense, but is made merely for the purpose of
describing the general principles of the invention. The
scope of the invention should be determined with
reference to the claims.
Referring to FIG. 1, there is illustrated a
tangential air separator system 10 particularly suited
for separating material, such as scrap paper, conveyed in
a stream of air inside a factory or other building. The
illustrated tangential air separating system l0 includes
an inlet duct 12 or network of inlet ducts, a tangential
separator apparatus 14, an outlet chute 16 leading from a
material discharge exit 18 of the separator apparatus 14
to a baler 20 or compactor, and a plurality of air
exhaust conduits 22,24 extending from the separator
apparatus 14. The illustrated system 10 is a "push type"
tangential separator wherein the air stream and conveyed
material are blown through the inlet ducts 12 into the
separator apparatus 14 with a fan (not shown) associated
with the inlet ducts 12 and located upstream of the
separator apparatus 14. The conveyed material is
effectively separated from the air stream within
separator chamber 30 within the apparatus 14. Most of
the air stream exits the separator chamber 30 via the air
exhaust conduits 22, 24 while the conveyed material exits
via the material discharge exit 18 to the chute 16 and
eventually to a baler 20 or compactor. The air stream
being discharged through the air exhaust conduits 22,24
215512
_g_
is then filtered and subsequently recycled and/or re-
introduced into the immediate environment.
The size of the separator apparatus 14 and
associated ducting is very much dependent on the volume
of the air stream necessary to efficiently convey the
material as well as the general character of the scrap
paper being separated. Further, the illustrated
embodiment can be easily modified to include multiple
inlets and/or multiple separating chambers sharing the
same air exhaust conduits.
FIGS. 2 and 3 illustrate side and front views
of the separator apparatus 14, respectively. As seen
therein, the separator apparatus 14 is a generally
cylindrical shaped casing 32 having a tangentially
oriented air and material inlet 34 located at or near the
top 36 of the cylindrical casing 32. In the illustrated
embodiment, the air and material inlet 34 is a 10 inch by
29 inch rectangular opening 38 with a two inch wide
flange 40 or collar disposed around the perimeter of the
rectangular opening 38 to facilitate attachment to inlet
duct 12. The illustrated embodiment further includes an
inlet transition adapter 42 having a length of about 39.5
inches to facilitate connection between a standard 18
inch diameter inlet duct 12 and the rectangular opening
38 of the air and material inlet 34 on the separator
apparatus 14. Advantageously, the inlet transition
adapter also increases the cross sectional area of the
incoming duct, e.g. by about 15%, thereby slowing the
velocity of the airstream slightly.
The separator apparatus 14 further has a
material discharge exit 18 located at the bottom 44 of
the generally cylindrical casing 32. The illustrated
material discharge exit 18 is a 29 inch by 29 inch
opening 46 with a two inch wide flange 48 disposed around
the perimeter of the opening 46 to facilitate connection
to a feed chute 16 leading to the baler 20 or compactor.
-10-
The illustrated separator apparatus further
includes two air exhaust conduits 22, 24 and a separator
chamber access door 50. The first air exhaust conduit 22
is peripherally attached to the perforated back outer
wall 52 of the cylindrical casing 32 and leads away
therefrom to an air outlet 54 located apart from the
cylindrical casing 32. The second air exhaust conduit.24
is adapted to connect to a side 56 of the cylindrical
casing 32 and remain in communication with the interior
of the cylindrical casing 32 and separating chamber 30.
In particular, the illustrated separator apparatus 14 has
a 36 inch diameter hole 58 centrally located on one side
56 of the generally cylindrical casing 32. The casing 32
also has a standard 36 inch diameter angle ring 60
extending from the side hole 58 for engagement with the
second air exhaust conduit 24 (See FIG. 1).
Referring now to FIG. 4, a cross-section view
of the separator apparatus 14 is shown depicting the
separation chamber 30 and the operative elements of the
separator apparatus 14. The illustrated separation
apparatus 14 includes two distinct separating devices.
The first separating device is the perforated arcuate
back outer wall 52 of the cylindrical casing 32 leading
to the first air exhaust conduit 22. The second
separating device is a perforated cylinder 64 centrally
disposed in the separation chamber 30 and generally
coaxial to the axis of the cylindrical casing 32. The
perforated metal cylinder 64 is dimensioned so as to
communicate with the second air exhaust conduit 24
through the side hole 58 as seen in FIG. 1.
As seen more clearly in FIG. 5, the perforated
surface 52 extends from the top 36 of the cylindrical
casing 32 and constitutes a substantial portion of the
its back wall. The cross sectional area of the
perforated surface 52 is about 18.4 square feet. The
perforated surface is preferably a #12 gauge perforated
sheet with a plurality of 0.15625 inch diameter holes 66
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separated by 0.1865 inch and having staggered centers.
Similarly, as seen in FIG. 6, the perforated cylinder 64
is comprised of the same #12 gauge perforated sheet with
a plurality of 0.15625 inch diameter holes 68 and is
dimensioned to be a 36 inch diameter tube about 29 inches
long. The perforated cylinder 64 is coaxially placed
within the cylindrical casing 32 aligned with the side
hole 58. The angle ring 60 is securely attached to one
end of the cylinder 64 and provides a support or
connector for engagement with the second air exhaust
conduit 24. The total cross sectional area of the
perforated cylinder 64 is about 22.5 square feet.
In operation, the incoming stream of air and
material enters the separating chamber 30 via the inlet
transition adapter 42 (See FIGS. 1 and 4). In addition
to connecting the separator apparatus 14 to the standard
inlet ducting 12, the inlet transition adapter 42 also
acts to slightly decelerate the stream due to the
generally increased cross-sectional area of the inlet
transition adapter 42. As the mixed stream enters the
separating chamber 30, it encounters the perforated
surface 52 of the separator apparatus 14. The dimensions
of the perforations 66 and cross sectional area of the
perforated surface 52 are chosen such that between about
50% and 75%, and more preferably about 60% of the volume
of the air stream is immediately removed (i.e. passes
through the back wall perforations) while retaining all
of the transported material within the separating chamber
30. The remaining air and the material entrained therein
continues to move through the separating chamber 30. As
it progresses through the separating chamber 30, much of
the material is forced towards the outer or back wall 52
of the cylindrical casing 32 as well as in a downward
direction due to the forces present within the chamber
coupled with the generally cylindrical configuration of
the separating chamber 30. Because of this natural
segregation of the entrained material towards the outer
2~~~~~~~
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walls, the residual air is then easily separated from the
material through the perforated cylinder 64 centrally
disposed within the separating chamber 30. Again, the
perforation size and dimensions of the perforated
cylinder 64 are chosen to allow most of the remaining
air, and only the air, to escape. The entrained material
continues to move in a generally arcuate path around the
cylindrical casing. When the entrained material reaches
the bottom 44 of the casing 32, the entrained material
escapes via the material discharge exit 18. Typically
the material continues through a feed chute 16 to a
horizontal compactor or baler 20.
The pressure drop between the inlet duct 12 and
the material discharge exit 18 is preferably accomplished
in three discrete steps. First, a small pressure drop is
realized as the incoming air flow traverses the inlet
transition adapter 42. In the preferred embodiment, the
cross-sectional area at the entrance to the inlet
transition adapter 42 is approximately 254 inz and
gradually increases to a cross sectional area of about
290 in2 at the inlet 34 to the separating chamber 30.
Second, a pressure drop is realized due to the removal of
a substantial volume of the air via the perforated outer
wall 52. The remaining air and material stream proceeds
at a velocity that is substantially slower than the
entrance velocity due to the removal of the transport
medium. Finally, another pressure drop is realized due
to the separation and removal of air from the interior of
the separating chamber. It is important to note that the
shape, location, and the dimensions of both separation
means 52 and 64 relative to one another as well as to the
inlet 34 and material discharge exit 18 are very
important considerations in the design of the present
separator apparatus 14 in order to achieve the desired
pressure drop, which has heretofore not been accomplished
in a "push-type" separator system.
z
-13-
The combination of two air separating devices
within a single separator apparatus, one peripherally
positioned and one centrally located, provide a
synergistic or at least a greater than expected reduction
in static pressure across the separator casing. By way
of comparison, the present embodiment demonstrates about
a 25% lower level of static pressure near the material
discharge exit than a comparably sized "push-type"
separator having only a centrally disposed exit.
Likewise, the present embodiment is believed to have a
much lower static pressure near the material discharge
exit than a comparably sized "push-type" separator having
only a peripherally or tangentially located exit. This
dual separation feature of the present embodiment
minimizes the problems associated with swirling dust and
other particles near the collection site. Further, the
dual separation feature allows the design of the
separator apparatus to be even more compact than previous
designs, for a comparable volume of flow, while
effectively separating the conveyed material.
As the air exits the separating chamber 30, it
is channeled by the multiple exhaust conduits 22, 24 and
released at a location that is a prescribed distance
apart from the separator apparatus 14. Specifically, the
air discharged from the air exhaust conduits 22, 24 can
be routed back to its point of origin to be re-used for
conveying additional material or can be discharged
exterior of the building. In addition, an appropriate
filter can be incorporated within the air exhaust
conduits 22, 24 such that the air can be safely
discharged inside the building.
Considering the operation of the presently
described embodiment, the preferred method of separating
material transported by a stream of air is defined by
four essential steps. These four steps include: (1)
receiving a stream of air and material at an inlet of a
casing, the inlet being disposed at the periphery of the
2195512
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casing; (2) removing or separating a large portion of the
incoming air stream via a perforated outer wall or other
peripheral air exit of the casing that is immediately
downstream of the inlet: (3) further removing or
separating most of the remaining air from the material
within the interior of the casing with a secondary
separating device: and (4) discharging the entrained
material via a material outlet, the material outlet being
located at the bottom of the casing and spaced a
sufficient distance from the inlet such that the pressure
drop between the inlet and the material discharge exit is
realized. As indicated above, the pressure drop between
the inlet and the material discharge exit is accomplished
in three discrete events corresponding to steps (1)
through (3) above. Further, as the air is removed or
separated in steps (2) and (3) above, it should be
channeled or directed away from the casing to one or more
air outlets by means of separate exhaust conduits
operatively associated with each of the separating
devices.
An alternative embodiment of such a tangential
separator is illustrated in FIGS. 7-9. As seen therein,
the separator apparatus 84 includes an inlet 86 for
stream of air and material, a separating chamber 88, a
material discharge exit 90 and a plurality of air exhaust
conduits 92, 94a and 94b extending from the separator
apparatus 84 to an air outlet 96. The conveyed material
is effectively separated from the air stream within the
separating chamber 88 where there is shown a perforated
metal surface 98 along the back wall of the cylindrical
casing 102 and a centrally disposed perforated cylinder
104, as described above.
The separator illustrated in FIGS. 7-9 is
generally the same as described with reference to FIGS.
1-6 except that the separator represented in FIG. 7-9
further includes modified air exhaust conduits 92, 94a,
94b in place of the first and second air exhaust conduits
2i955i2
-15-
22, 24 described with reference to FIGS. 1-4. As with
the previous described embodiment, the separation
apparatus 84 includes two distinct separating devices.
The first separating device is the perforated arcuate
back outer wall 98 of the generally cylindrical casing
102. The perforated surface 98 allows much of the air to
exit the separating apparatus 84 in a generally
tangential orientation. In particular, as the stream of
air and entrained material enters the separating chamber
88 via the inlet 86, it encounters the perforated surface
98 of the separator apparatus 84. Much of the air stream
passes through the perforations while the entrained
material is directed in a downward orientation by the
arcuate perforated surface. The dimensions of the
perforations and cross sectional area of the perforated
surface 98 are chosen such that between about 50% and
75%, and more preferably about 60% of the volume of the
air stream passes through the perforated surface 98 and
the entrained material stays within the separating
chamber 88.
The remaining portion of the air subsequently
encounters the second air separating device. The second
air separating device is a perforated cylinder 104
centrally disposed in the separation chamber 88 and
generally coaxial to the axis of the cylindrical casing
102. Again, the size of the perforations as well as the
dimensions of the perforated cylinder 104 are chosen to
allow much of the remaining air within the separating
chamber 88 to be separated from the material. The
separated air is then channeled away from the separator
apparatus 84 via dual air exhaust conduits 94a and 94b.
The dual air exhaust conduits, 94a and 94b, are attached
to each end 106, 108 of the perforated cylinder 104 and
extend from the respective sides 110, 112 of the
separator apparatus 84. The entrained material remaining
within the separating chamber 88 continues along the
CA 02195512 2005-O1-07
w
-16-
original path to the bottom 114 of the casing 102 and
eventually out the material discharge exit 90.
The distinguishing feature between this
illustrated embodiment and the previously described
embodiment is found in the configuration of the air
exhaust conduits 92, 94a and 94b. Advantageously, the
central air exhaust conduits 94a and 94b, in the
embodiment shown in FIGS. 7-9, is adapted to provide bi-
directional flow of the air out of the separating chamber
88 through each side 110 and 112 of the cylindrical
casing 102. The bi-directional flow from each side 110,
112 of the separator apparatus 84 tends to maintain the
air exit velocity at moderate levels. The plurality of
air exhaust conduits 92, 94a and 94b are joined together
at a location downstream of the separator apparatus 84
such that the exit air flow is directed to a~single air
outlet 96. The air discharged from the air outlet 96 is
first passed through a filter 116 to remove dust and
other contaminants so that the exit air can be safely re-
introduced into the immediate environment. Such an
arrangement retains the advantage of having multiple air
exits in a separator system while simplifying the
incorporation of a filter.
From the foregoing, it should be appreciated
that the present invention thus provides an improved
method and apparatus for separator material entrained in
a stream of air or similar transport medium. Further, it
will be apparent that various changes may be made in the
form, construction and arrangement of the parts thereof
without departing from the spirit and scope of the
invention or sacrificing all of its material advantages,
the forms hereinbefore described being merely exemplary
embodiments thereof. Therefore, it is not intended that
the scope of the invention be limited to the specific
embodiments and processes described. Rather, it is
intended that the scope of this invention be determined
by the appending claims and their equivalents.
