Note: Descriptions are shown in the official language in which they were submitted.
CA 02303928 2000-03-15
WO 99/18270 PCT/US98/20583
IMPROVED DISTRIBUTION OF FIBER
FROM PNEUMATIC FIBER CONVEYING SYSTEM
Field of the Invention
This invention relates to handling bulk textile fiber and more
particularly to processes and equipment for handling textile fiber in a
pneumatic conveying system.
Background of the Invention
One of the difficulties in handling textile fiber is the tendency for
fiber to settle in mounds or piles when it is desirable that the fiber be
generally uniformly dispersed. It appears to be a problem regardless of
whether the fiber is individualized fiber filaments, in clumps, tufts or in
some other fo»n. In the production of spunlaced nonwoven fabrics, more
uniform basis weight distribution is obtained when the fiber is more
uniformly dispersed across the width of the fabric at the earliest stages of
1 S formation. E. I, du Pont de Nemours and Company, Wilmington, DE
(DuPont) has iinvested considerable time and effort to improve uniformity in
the manufacture of its Sontara~ spunlaced fabrics. DuPont's focus for
providing the desired uniformity has been the chute feeder which creates a
batt of fibers for processing into the finished spunlaced fabric. The chute
feeder is disclosed in 1JS Patent 5,606,776 to Freund et al. and includes a
bin
or hopper in which fiber is first provided. The fiber is typically supplied by
a pneumatic conveyor and in the conventional arrangement, the fiber enters
an inlet in one wall of the bin or hopper. The fiber in the bin or hopper
tends
to pile into a mound close to the center near the inlet. The batt from the
chute feeder tends to have a heavier or denser portion along the center where
the fiber was mounded in the hopper. The denser and heavier portion tends
to be found throughout the process and even in the final product.
Summary of the Invention
Accordingly, it is an object of the present invention to overcome
the above notE;d drawbacks of the prior art and more particularly to provide
improved fiber distribution of fiber in fiber handling system.
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One idea proposed to better distribute the fiber across the width of
the bin is to divide the pneumatic conveyor into a plurality of flows of
fiber.
Each of the flows would be provided to separate inlets in the bin and being
evenly separated so that the one central mound would be separated into a
5 series of smaller mounds. The chute feeder would then be able to even out
the less dramatic unevenness of the plurality inlet. However, it has been
found that the effects of even small scale unevenness can be found in the
final product. Moreover, fiber does not naturally distribute itself uniformly
across a pneumatic conveying tube thus making separation into a plurality of
10 evenly divided flows quite unlikely.
Thus, it is a further object of the present invention to divide a
single flow of pneumatically conveyed fiber into a plurality of generally
evenly divided flows of fiber.
Brief Description of the Drawings
15 The 'invention will be more easily understood by a detailed
explanation of the invention including drawings. Accordingly, drawings
which are particularly suited for explaining the invention are attached
herewith; however, it should be understood that such drawings are for
explanation only and are not necessarily to scale. The drawings are briefly
20 described as follows:
Figure 1 is a cross sectional side elevational view of a chute
feeder with a pneumatic conveying system illustrated schematically
providing fiber to the chute feeder.
Figure 2 is a cross sectional view of the chute feeder of Figure 1
25 taken along the Line 2-2.
Figure 3 is a perspective view of a first embodiment of a
distributor.
Figure 4 is a cross sectional view of the distributor of Figure 3
taken along the Line 4-4.
30 Figure S is a perspective view of a second embodiment of a
distributor.
Figure 6 is a cross sectional view of the distributor of Figure 5
taken along the Line 6-6.
2
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WO 99/18270 PCT/US98/20583
Detailed Description of the Invention
Turning now to the drawings, there is shown in Figure 1 a chute
feeder 10 whit:h receives fiber in the form of fiber tufts from a pneumatic
conveying system 20 and forms a batt 12 from the fiber. The chute feeder
5 10 includes a hopper 15 for receiving the fiber. It is preferred that the
fiber
be as uniformly distributed across the hopper 15 as possible. Thus, in
accordance with the invention as shown in Figure 2, the hopper 1 S includes
a plurality of inlets 18 which are evenly spaced across the width thereof.
The inlets 18 ase fed b;y a plurality of feed conduits 24 of the pneumatic
conveying system 20.
Pneumatic conveying systems are well known and in common
usage in the textile industry and the pneumatic conveying system 20 of the
present invention is intended to be generally representative of such systems
with the addition of a unique element. As with all pneumatic conveying
1 S systems, fiber typically in the form of tufts is fed into a moving
airstream
within a duct or, conduit and carried along with the air stream. The
pneumatic conveying system 20 comprises a primary conduit 21 into which
such fiber is fe;d and carried by the airstream. However, in the subject
invention the pneumatic conveying system 20 includes a distributor 30
20 which divides the fiber laden airstream into a plurality of fiber laden
airstreams which are then carried in the feed conduits 24. The distributor 30
is not just a simple branching of the conduit because it is also intended to
evenly divide or distribute the fiber in each of the airstreams in the feed
conduits 24. F3ecause the fiber is not generally evenly distributed across the
25 duct of a pneumatic system, evenly dividing the fiber is no simple task.
The
fiber tends to be carried along primarily at the bottom of the duct or along
the outside of .any bend. These considerations would need to be
incorporated alto any means for evenly dividing the fiber.
Turning now to Figures 3 and 4, a first embodiment of the
30 distributor 30 is illustrated as having the appearance of a rather flat
square
box. The box or housing is defined by generally parallel, opposed and
spaced apart fiirst and second walls 36 and 37 with deflector walls 38
extending bet«reen the first and second walls 36 and 37 at about the
3
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WO 99/18270 PCT/US98/20583
periphery thereof enclosing an interior space 39. In the illustrated
embodiment, there are shown to be four deflector walls 38 closing the space
between the first and second walls 36 and 37. In addition, there are four
peripheral walls 43 at the edges of the first and second walls 36 and 37 and
5 just outside of the deflector walls 38 from the interior space 39. The
peripheral walls 43 provide structural support for the distributor 30 and may
be replaced by other suitable bracing or deleted entirely should the deflector
walls 38 provide adequate rigidity and structural integrity. From the
drawings, the deflector walls are not arranged at a normal or perpendicular
10 angle to the first or second walls 36 and 37 for reasons which will be
discussed below, so in the preferred embodiment, peripheral wails 43
provide structural integrity.
The distributor 30 includes a primary inlet 31 connected to the
primary air conduit 21 of the pneumatic conveying system 20 for receiving
15 fiber. The primary inlet 31 is connected to the second wall 37 by a
conicaliy
diverging portion 32. The conicaliy diverging portion 32 has an inner
diameter that substantially increases from the primary inlet 21 to the primary
opening 41 which is about twice the diameter of the primary inlet 31. The
primary opening 41 is positioned in about the center of the second wall 37
20 and more preferably, at the center of the interior space 39 between the
deflector walls 38. In the illustrated embodiment, there are four outlets 34
arranged adjacent the intersections of the deflector walls 38. The outlets 34
are connected to the feed conduits 24 as shown in Figure 1 to the chute
feeder 10.
25 As briefly noted above, the distributor 30 divides the fiber laden
airstream in the pneumatic conveying system 20 in a way that rather equally
divides the fiber into a plurality of separate airstreams. The process of
separation is rather simple and may be understood by following the path of
the fiber and air in the distributor. Clearly, it is understood that the air
will
30 be moving through the distributor 30 by the force of whatever fans or
blowers are used within the overall pneumatic conveying system 20 and the
to the extent that the separate ports 34 and their associated feed conduits
have similar back pressure, the air flow (not considering the fiber) will be
4
CA 02303928 2000-03-15
generally equally divided. Thus the challenge is to get the air to carry
roughly equal amounts of fiber out each port 34.
_ The fiber and airstream is primarily divided by a blunt impact
against the first wall 36. The airstream tends to react to the blunt impact by
spreading radially outwardly in the relatively flat distributor 30 towards the
deflecting walls 38. Thc: fiber is also spread radially outward by the blunt
impact except that it tends to remain close to the first wall 36 as it moves
towards the deflector walls 38. The deflector walls 38 are arranged at an
angle A to the furst wall 36, being slightly greater than perpendicular or 90
to degrees thereby directing the fiber away from the first wall 36 and back
towards the center of the; interior space 39. Preferably the angle A is about
105° but it should be understood that a fairly broad range from near
95° up
to about 135° rnay be suitable.
Bumping the fiber back toward the center of the interior space
39 reduces the opportunity for the fiber to settle out of the airstream by
keeping the system flowing. It is also preferred that the ports 34 are
positioned at the intersection of the deflector walls 38 thereby being
farthest
- from the primary inlet 3 1. Although some fiber will surely impact the
center of each of the deflector walls 38, the air will naturally move toward
2 o the ports 34 picking up fiber with it.
There ar~~ of course other considerations that will help optimize the
operation of the distributor 30. For example, it is most desirable that the
primary condui~: have a ~;enerally straight run in a vertical direction for
the
last fifteen or more feet leading to the primary inlet 31 without making any
significant turns or bends which would tend to make the fiber favor any one
side of the primary inlet 31 as it enters the distributor. For the best
results,
the primary conduit 21 should make about a fifteen foot vertical run
upwards into the bottom of a horizontally arranged distributor 30. By
providing that tine final run be vertically upward, gravity tends to help
distribute fiber ;in the
5
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primary air conduit 21. providing the most even distribution of fiber. It
should be noted that at any one instant in time, the fiber may not be evenly
distributed sir.~ce it may be in clumps. However, even over relatively short
periods of time, such as several minutes, the amount of fiber going through
5 each of the ports 34 cam be fairly even. With the fiber being fairly evenly
divided among the various feed conduits 24, then the fiber may be more
evenly distributed laterally across the chute feeder 10.
It should be: noted that the distributor 30 is amenable to having
more or less outlets. For example, the illustrated embodiment (Fig. 3) has
the shape of a square box with four outlets. Other designs were tested
having six anti eight outlets. The six outlet design had the shape of a
hexagon and the eight outlet design had the shape of a octagon. Clearly, one
can envision a design having a large number of outlets where the deflecting
walls start to appear like a continuous circle.
1 S A second embodiment of the distributor, indicated by the number
130 is illustrated in Figures 5 and 6. The distributor 130 has the appearance
of a centrifugal fan with a plurality of outlets. The distributor 130
comprises
a housing 135 with a paddle fan 143 arranged to rotate about a shaft or hub
144. The hub 144 is driven by a motor (not shown) arranged outside the
20 housing 135 and preferably attached to the outside of the housing 135 by
suitable means such a:> bolts. The paddle fan 143 includes a number of
paddle blades 145 which rotate about the hub 144 so as to push air and fiber
toward the outlets 134. An inlet 131 is arranged to coincide with the hub
14.4 of the paddle fan 143 such that the primary air conduit leading to the
25 inlet 131 is generally coaxial with the hub 144. With this arrangement, the
air and fiber enter the housing from the primary air conduit 21 along a path
generally coa;Kial with the hub 144 and turns and centrifugally spreads out
within the housing 13 5 moving to one of the outlets 134.
In the second embodiment, there are preferably four outlets 134
30 although more or less outlets may be suitable. Four outlets were selected
as
a practical matter since more outlets would have made the design and
construction of the housing 135 more complicated. The housing 135
comprises fir:>t and second generally parallel, opposed and spaced apart
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walls 136 and 137 and contoured side walls 138 connecting the first and
second walls at about: their periphery. The contoured side walls 138 of the
housing 135 .are arranged radially from the distal ends of the paddle blades
145 and contoured to at least partially follow the circular path of the distal
5 ends of the paddle blades 145. The contoured side walls 138 straighten to
foam a tangential porl:ion terminating at the outlet 134. As the outlets 134
are generally equally spaced around the periphery of the housing 135, t~he~
amount of fiber and air will be substantially evenly divided among the
outlets.
10 One particular advantage of the second embodiment of the
distributor 130 is revealed when one of the outlets may become blocked or
occluded by fiber which has stopped or settled down in the feed conduit 24.
In this second embodiment, the paddle fan 143 continues to push air and
fiber into each outlet I. 34 at the urging of the motor (not shown) such that
15 the pressure in the occluded duct will increase urging the blockage to move
along and in most cases abate the blockage. Another feature and advantage
of the second .embodiment is that it is less sensitive to gravitational
effects as
the centrifugal) forces created by the motor (not shown) and fan blades 145
have more inflluence o:n the distribution of fiber in the distributor 130. The
20 second embodiment may provide an additional advantage in that it may
eliminate the need far .an additional fan for the pneumatic conveying system
or reduce the energy requirements of the pneumatic conveying system.
The: foregoing description and drawings were intended to explain
and describe the invention so as to contribute to the public base of
25 knowledge. In exchange for this contribution of knowledge and
understanding,, exclusive rights are sought and should be respected. The
scope of such exclusive rights should not be limited or narrowed in any way
by the particular details and preferred arrangements that may have been
shown. CIearI;y, the scope of any patent rights granted on this application
30 should be measured and determined by the claims that follow.
7
