Note: Descriptions are shown in the official language in which they were submitted.
CA 02610190 2007-11-13
WOOD CHIP FLINGER AND METHOD
Background of the Invention
The present invention relates generally to the field of wood chip processing,
and more
particularly to a machine and associated method for dense packing of wood
chips for storage,
transport, or further processing.
One major factor in the cost of wood chips for paper making is the cost of
transporting
the wood chips from the chip manufacturing site to the paper mill. The wood
chips are typically
transported in rail cars, but may also be transported in barges, trailers, or
the like. Typically, the
transportation costs are based primarily on the number of containers used to
ship a given load
of wood chips. Thus, the more densely containers can be packed, the lower the
transportation
costs for delivering a given amount of useable wood chips.
Space considerations are also relevant in the storage and processing of wood
chips.
For instance, the storage of wood chips on site, such as at a pulp mill,
consumes space. As
such, it is advantageous to have the wood chips densely packed when "stacking"
the wood
chips for storage.
While a number of wood chip handling techniques have been proposed in the
industry,
there remains a need for alternative wood chip handling techniques,
particularly ones that allow
for dense packing of the wood chips for storage and/or transport.
Summary of the Invention
The present invention provides an assembly for processing wood chips with a
novel
blade profile and related methods. In one embodiment, the blade profile is a
stepped blade
profile with a plurality sections forming a rotationally forward face, with
neighboring sections
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CA 02610190 2007-11-13
being non-collinear and at least one of the sections being parallel to the
axis. In another
embodiment, the blade profile includes first, second, and third sections; the
first section being
generally centrally disposed and having a longitudinal extent that is at
least'/4 of a relevant
dimension; the second section disposed between the first section and the third
section and non-
collinear with the third section; the third section having a longitudinal
extent that is at least 1/8 of
the relevant dimension; with the sections disposed relative to the axis in
advantageous
positions. In yet another embodiment, the blade profile is such that second
and third sections of
the blade having approximately equal longitudinal extents relative to the
axis, but the tilt-angle-
weighted surface area of the second section is substantially less than the
third tilt-angle-
weighted surface area of the third section. The assembly advantageously allows
wood chips to
be packed with a density greater than that achieved using conventional free-
fall techniques,
such as at >_20% more than that achieved with the conventional free-fall
techniques.
More particularly with respect to one embodiment, the present invention
provides an
assembly for processing wood chips, comprising: a drum disposed so as to
rotate about a
generally horizontal longitudinal axis, the drum comprising a central core and
at least first and
second blades extending outwardly from the core and circumferentially spaced
from one
another; the drum having a longitudinal length; a motor operatively connected
to the drum and
supplying rotational power thereto; the first blade having a stepped blade
profile with a plurality
sections forming a rotationally forward face, with neighboring sections being
non-collinear and
at least one of the sections being parallel to the axis. The second blade may
have a blade
profile similar to the blade profile of the first blade and the blades may
each extend substantially
across the width of the drum. At least two of the sections may be parallel and
the blade profile
may vary discontinuously in blade axial tilt angle.
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Other aspects of the assembly and related methods are also evident from the
following
description and corresponding drawings.
Brief Description of the Drawings
Figure 1 shows one embodiment of the device of the present invention employed
in a
wood chip loading station for filling railcars.
Figure 2 shows a side view of one embodiment of the device of the present
invention.
Figure 3 shows a perspective view of a baseplate assembly.
Figure 4 shows a simplified top view of the drum and directing wall of one
embodiment.
Figure 5 shows a top (radial) view of a blade profile of the drum of Figure 4.
Figure 6 shows a side view, perpendicular to the rotational axis, of a drum
(with endcaps
removed for clarity) with a blade having the blade profile of Figure 5 (with
joining sections
removed for clarity).
Figure 7 shows a top (radial) view of an alternate blade profile.
Figure 8 shows a top (radial) view of an alternate blade profile.
Figure 9 shows a top (radial) view of an alternate blade profile.
Figure 10 shows a top (radial) view of an alternate blade profile.
Figure 11 shows a top (radial) view of an alternate blade profile.
Description of the Preferred Embodiments
In order to provide a better understanding of the present invention, one
embodiment of
the wood chip handling device according to the present invention is shown in
Figure 1 in the
context of a wood chip loading station 10 for filling railcars 12. The wood
chip handling device,
generally indicated at 20, is shown installed in a tower structure 16 that
extends above a rail line
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with a railcar 12 thereon. Wood chips 5 are fed to the handling device 20 in
the tower 16 by any
suitable means, such as by conventional conveyor system 14 (only the output
funnel of which is
shown for clarity), or alternatively via a pneumatic means into a cyclone, or
by other like means
known in the art. While the input feed system (e.g., conveyor system 14) is
shown with only one
output, it should be understood that the input feed system may have multiple
outputs, such as in
a so-called "pants leg" bifurcated chute system known in the art. There may be
a handling
device 20 at each output, or at only one output, as is desired. The handling
device 20 takes the
input stream of wood chips from the conveyor 14 and directs it into the
railcar 12 so that the
wood chips 5 are packed in railcar 12. In most applications, the railcar 12
will be moved
underneath the handling device 20 during the loading process so as to fill the
entirety of the
railcar's length, but the device 20 (with or without the tower 16) may
alternatively be moved
while the railcar 12 is held stationary, if desired.
One embodiment of the handling device 20, sometimes referred to herein as the
"flinger," includes a frame 22, a motor 24, a feed chute assembly 30, and a
drum 80. See
Figure 2. The frame 22 supports the motor 24, feed chute assembly 30, and drum
80, and may
take any suitable form known in the art, such as welded assembly of angle
iron. The motor 24
supplies rotational power to the drum 80, typically via a pulley and belt
arrangement (not shown
in detail). The motor 24 may be of any type known in the art, but is typically
an electric motor of
approximately fifteen horsepower or more.
Disposed above the drum 80, and between the drum 80 and the conveyor system
14, is
a feed chute assembly 30. Referring to Figures 3-4, the feed chute assembly 30
includes a
sloped baseplate assembly 40 and an optional deadwall 60 towards the output
end 50 thereof.
The baseplate assembly 40 of a preferred embodiment includes a baseplate 42
and dividers 46.
The baseplate 42 is a sturdy, substantially rectangular plate with side
flanges 44. The
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CA 02610190 2007-11-13
baseplate 42 is disposed in a tilted orientation, so that the input end is
higher than the output
end 50. The output end 50 preferably has a stepped profile, with a center
section 52 flanked by
respective side sections 54, and corresponding transition sections 56. The
center and side
sections 52, 54 are preferably straight and parallel to one another, with the
center section 52
ending later than the side sections 54. The transition sections 56 provide a
transition between
the center section 52 and the side sections 54. In a preferred embodiment, the
overall
appearance of the output end 50 of the baseplate 42 is that of a trapezoid
tongue as shown in
Figure 4, but this is not required. It should be noted that the baseplate
assembly 42 may be
oriented so as to feed chips from the input end to the output end in a
direction that is either
forward or backward relative to the direction of rotation of drum 80, as
needed or required by
installation circumstances.
Two dividers 46 may be moveably attached to the baseplate 42 so as to be
selectively
positioned by pivoting about corresponding pivot points 47 (e.g., shouldered
bolts extending
through the baseplate 42). The location of the upper ends of the dividers 46
may be adjusted
with respect to the baseplate 42 using a suitable adjusting mechanism 48. By
way of non-
limiting example, the adjusting mechanism 48 may take the form of a crank and
threaded rod
arrangement, with suitable pivoting connections between the tops of the
dividers 46 and the
threaded rods. Of course, other means known in the art may be used to control
the position of
the upper ends of the dividers 46. Whatever means is selected, it will be
advantageous to
position the controls thereof (e.g., the crank) so as to allow easy access
thereto by a user during
operation of the handling device 20. The purpose of the dividers 46 is to
control the flow ratio of
the wood chips flowing down the baseplate assembly 40 to the center 82 and
side portions 84 of
drum 80.
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The directing wall, or deadwall, 60 is a generally vertical wall that acts to
focus the flow
of the wood chips flowing down the baseplate assembly 40 generally vertically
onto the drum
80. As shown in Figure 4, the directing wall 60 may include a center section
62, flanking side
sections 64, and appropriate offset sections 66 therebetween. The center and
side sections
62,64 are preferably straight and parallel to one another, and preferably are
disposed a height
from the center of drum 80. The offset sections 66 are preferably generally
perpendicular to the
center and side sections 62,64 and are likewise disposed at a height from drum
80. Thus, the
directing wall 60, when viewed from above, preferably has the shape shown in
Figure 4. It
should be noted that the offset sections 66 may simply connect the center and
side sections 62,
64; or, alternatively, the offset sections 66 may be longer such that they
extend toward the feed
chute baseplate assembly 40 to a point beyond the intersection with the side
sections 64 as
shown in Figure 4. This optional "extra" length for the offset sections 66 is
believed to aid in
achieving the desired side-to-side balance of wood chips being supplied to the
drum 80.
Further, the directing wall 60 should be located, and be of sufficient height,
so that the wood
chips from the baseplate 42 impact in the vertical middle of the directing
wall 60. The bottom of
the directing wall 60 should be relatively close to the drum 80, with a
clearance therebetween of
1/2 to three inches believed advantageous when the baseplate assembly 40 is
disposed on the
drum's rotationally downstream side of the directing wall 60. In addition, the
side profile of the
bottom of the directing wall 60 may be angled or curved to follow the contour
of the drum 80 if
desired.
The directing wall 60 is located forward of the output end 50 of the baseplate
assembly
40, so that a substantial gap is formed therebetween to allow passage of the
wood chips without
jamming as the wood chips change flow direction. Further, while the directing
wall 60 may be
located prior to top dead center (behind the rotation axis 86 of the drum 80),
the directing wall is
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CA 02610190 2007-11-13
advantageously located at a position that is beyond top dead center of the
drum 80 (see Figures
2 and 4). The center section 62 of the directing wall 60 may be narrower than
the center section
52 of baseplate 42 by about an inch, with the transition sections 56 of the
baseplate 42
extending laterally approximately another two inches. Of course, the gap size
is at least
partially governed by the spacing between the output end of the baseplate
assembly 40 and the
location of the directing wall 60. The position of the directing wall 60
relative to the baseplate 42
and/or drum 80 may be permanently fixed; however, the position of the
directing wall 60 may be
adjustable (for instance, 3 inches) in some embodiments of the present
invention, such as by
mounting the directing wall 60 using bolts, with multiple bolt holes provided
in the frame 22. It
may be advantageous to vary the gap size, nominally ten to twelve inches, in
proportion to the
desired output rate of the device 20.
While the space above the baseplate 42 of the feed chute assembly 30 may be
open,
the feed chute assembly 30 may optionally include a cover (not shown) spaced
from the
baseplate 42 to help contain any errant wood chips. The optional cover may
extend above the
top of the directing wall 60, and be spaced therefrom, so as to provide an
overflow route, if
desired.
The drum 80 is mounted for rotation about a generally horizontal axis 86, and
supported
by the frame 22. The drum 80 may be mounted to an axle 112, which may be a
central shaft or
a pair of stub shafts, which is in turn supported by suitable bearings mounted
to the frame 22.
As indicated above, the axle 112 should have a pulley, gear, or like means for
accepting non-
gravitational rotational power to turn the drum 80, such as from motor 24. The
drum 80 includes
a main body core 90 with a plurality of outwardly extending blades 100, and
preferably a pair of
lateral endcaps 94. The main body 90 of the drum 80 may have a circular cross-
section, but
preferably has a faceted cross-section, such as an octagonal cross-section as
shown in Figure
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CA 02610190 2007-11-13
5. The blades 100 are mounted to the core 90 so as to extend away from the
surface thereof;
for instance, the blades 100 may extend generally perpendicular from the
corresponding facet
92 forming the perimeter of the drum's core 90. The blades 100 should
preferably extend from
one lateral endcap 94 to the other.
Each blade 100 may have an approximately uniform height, and the blades 100
are
preferably substantially identical, but neither aspect is strictly required
for all embodiments.
Each blade 100 is formed by a plurality of sections: a center section 102,
respective end
sections 106, and intermediate sections 104. For the embodiment shown in
Figures 4-6, these
sections are all generally straight and parallel to each other. Further, for
the embodiments of
Figures 4-6, the center section 102 is disposed rotationally forward,
proximate forward facet
joint 92a of facet 92; end sections 106 are disposed rotationally rearward,
proximate rear facet
joint 92c of facet; and intermediate sections 104 are disposed therebetween,
approximately in
the middle of facet 92. The center section 102 is disposed in a centered
position with respect to
the longitudinal width W of drum 80. The center section 102 typically has a
longitudinal extent
(i.e., in the direction of axis 86) of approximately'/4 to'/ the width W of
drum 80. The
intermediate sections 104 are disposed longitudinally outboard of the center
section 102, at a
position that is slightly rotationally retarded with respect to the center
section 102. Each
intermediate section 104 may have a longitudinal extent of at least 1/8 the
width W of drum 80,
and advantageously approximately 1/6 of width W. The intermediate sections 104
may be
joined to the center section 102 by corresponding offset sections 108 that run
generally
perpendicular to axis 86. The end sections 106 are disposed outboard of their
respective
intermediate sections 104, at a position that is slightly rotationally
retarded with respect to the
corresponding intermediate section 104. The end sections 106 may have a
longitudinal extent
of at least 1/8 the width W of drum 80, and advantageously approximately 1/6
the width W. The
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CA 02610190 2007-11-13
end sections 106 may be joined to their respective intermediate sections 104
by additional offset
sections 108. When viewed from a forward direction, the combination of the
sections
102,104,106 appears to be gapless in the longitudinal direction (direction
parallel to axis 86).
When viewed from a radial direction (normal to the facet 92), it can be easily
seen that the
intermediate section 104 is disposed between the center section 102 and the
corresponding end
section 106, both rotationally and longitudinally.
The blade sections 102,104,106 for the embodiment of Figure 5 are generally
straight
and flat and disposed so as to extend outwardly generally perpendicular from
the corresponding
facet 92 forming the perimeter of the drum's core 90. As can be seen in Figure
6, this
arrangement results in the plane of the blade sections 102,104,106
intersecting a theoretical
radial plane from axis to where the respective section mounts to facet 92
(i.e., the base of the
section) at an angle a. Because this angle a represents the relative tilt of
the section relative to
a radial projection, this angle a is referred to as the "tilt angle" or "axial
tilt angle" of the blade
section. With reference to the cross-sectional view taken perpendicular to
axis shown in Figure
6, line A extends from axis 86 to the centerpoint 102c of center section 102,
line B extends from
axis 86 to the centerpoint 104c of an intermediate section 104, and line C
extends from axis 86
to a centerpoint 106c of an end section 106. Angle aA represents the tilt
angle of the center
section 102; angle aB represents the tilt angle of the intermediate section
104; and angle ac
represents the tilt angle of the end section 106. As can be seen, because
intermediate sections
104 are disposed toward the middle of facet 92, and are therefore closest to
being directly
above axis 86, the tilt angle aB of the intermediate sections 104 are
relatively low, and
advantageously approximately zero. In contrast, the tilt angles of the center
section 102 aA and
the end section 106s ac are relatively larger. As also can be seen in Figure
6, Line A forms a
forward angle relative line B, while line C forms a rearward angle relative to
line B.
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One parameter that helps describe the geometry of a section of the blade
profile is the
tilt-angle-weighted surface area of the section. Generically, the tilt-angle-
weighted surface area
of a blade section is the integral of the incremental surface area times the
absolute value of the
tilt angle a of the incremental segment, integrated across the section's
longitudinal length. For
the blades of Figure 5, the tilt angle for a given section is constant across
the longitudinal extent
of the section. Thus, the tilt-angle-weighted surface area is simply the
forward facing surface
area of the section multiplied times the absolute value of the relevant tilt
angle a. Thus, for the
blades of Figure 5, the intermediate sections 104 have a tilt-angle-weighted
surface area that is
relatively small, because the tilt angles aB of these sections 104 are very
small. Indeed, if the
intermediate sections 104 are disposed exactly in the middle of facet 92, then
their tilt-angle-
weighted surface areas would be approximately zero. In contrast, the tilt-
angle-weighted
surface area of end section 106 is substantially larger than the neighboring
intermediate section
104 due to the significantly larger absolute tilt angle ac and approximately
equal surface areas.
However, the tilt-angle-weighted surface area of the end section 106 is
smaller than the tilt-
angle-weighted surface area of the center section 102 because center section
102 has more
surface area (e.g., is longitudinally longer), but approximately equal
absolute value of tilt
angle a.
The blade sections 102,104,106 for the embodiment of Figure 7 are likewise
generally
straight and flat and disposed so as to extend outwardly generally
perpendicular from the
corresponding facet 92. The blade profile shown in Figure 7 differs from that
of Figure 5
primarily in that the center section 102 and the intermediate sections 104
overhang a short
distance from the point of intersection with the offset section 108 connecting
to the next outward
section. Like for the blades of Figure 5, the calculation of the tilt-angle-
weighted surface area
for each section of the blades 100 in Figure 7 is straightforward.
CA 02610190 2007-11-13
The blade sections for the embodiment of Figure 8 are likewise generally
straight and
flat, but the intermediate sections 104 and the end sections 106 disposed so
as to extend
outwardly at a rearward angle relative to the center section 102. Because the
intermediate
sections 104 and end sections 106 are both angled and offset, a theoretical
line from
centerpoint 106c of end section 106 to the centerpoint 102c of center section
102 does not pass
through the centerpoint 104c of intermediate section 104. The calculation of
the tilt-angle-
weighted surface area for center section 102 remains straightforward. The
calculation of the tilt-
angle-weighted surface areas for intermediate sections 104 and end sections
106 are more
complex, but it remains true that the value for tilt-angle-weighted surface
area of end section
106 is substantially larger than that for the neighboring intermediate section
104.
The stepped blade profile shown in Figures 5, 7, and 8 results in the blade
100 having
an blade axial tilt angle a that varies discontinuously across the width W of
the core 90. That is,
moving across the width W of the core 90 (parallel to axis 86) the blade axial
tilt angle a jumps
from one value to another in discontinuous fashion when moving from one blade
section to
another. In addition, it should be noted that the end sections 106 are not
simply co-linear
extensions of the intermediate sections 104. Instead, the centerpoint 106c of
end section 106 is
disposed off a theoretical line connecting the centerpoint 104c of
intermediate section 104 and a
point 110 on the intermediate section 104 closest to center section 102.
Further, the blade
profiles of Figures 5, 7, and 8 can be seen to have a greater portion of the
blade 100 disposed
toward the forward and rearward portions of facet 92. Thus, there is
proportionally a greater
amount of blade surface area located at high tilt-angle positions than in the
blade designs
shown in U.S. Patent No. 6,811,020.
Increasing the relative percent of high tilt-angle positions (either positive
or negative) for
a blade profile is believed to increase the ability of the blade 100 to spread
the output pattern
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210 at a given drum rotational speed. Referring to Figure 2, the angular arc
(3 of the output
pattern 210 may be increased by having greater tilt-angle-weighted surface
area. Thus, for a
given desired output pattern angular arc R, the rotational speed of the drum
80 may be lessened
than with the design of the '020 patent. The lower rotational speed means that
the wood chips 5
being flung from the drum 80 have less kinetic energy, which in turn means a
reduction in
undesirable splatter.
While the discussion above has been in terms of the blade's forward face being
divided
into five sections, one center 102, two intermediate 104, and two end 106,
this is not required,
and it should be understood that the blade's forward face may be divided into
more three or
more sections, some of which may be rearwardly angled and others of which may
not, and such
configurations are intended to be within the scope of the present invention.
It is believed
advantageous if the blade is symmetric; thus, blade section counts of three,
five, seven, and the
like are believed advantageous. Further, it should be noted that, within the
context of the
present invention, the sections may have a curving profile (longitudinally
and/or radially) if
desired.
One example of an alternative blade profile is shown in Fig. 9. In this
profile, the blade
100 has a center section 102 and respective end sections 106, without
intervening intermediate
sections 104. Thus, the stepped blade profile of Figure 9 represents a
simplified version of the
blade profile shown in Figure 5, with the rotationally forward face of this
blade profile formed of
two end sections 106 and a center section 102. As with the blade profile of
Figure 5, the center
section 102 and end sections 106 of the blade profile of Figure 9 are
advantageously positioned
at the juncture of adjoining facets 92. Another example of an alternative
blade stepped profile is
shown in Figure 10. This profile is similar to that of Figure 9, but with the
end sections 106
being rearwardly angled relative to center section 102, rather than parallel
thereto. As above,
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CA 02610190 2007-11-13
the center section 102 is advantageously positioned at the juncture of
adjoining facets 92 for
this profile.
The discussion above has been in terms of the center section 102 being
rotationally
forward. While this arrangement is believed to be advantageous, it is not
required. Indeed, the
stepped blade profile of Figure 11, which is essentially an inversion of the
blade profile of
Figure 5 has the center section 102 positioned rotationally rearward relative
to the end sections
106. Of course, other blade profiles may be likewise inverted. However, blade
profiles with
center sections 102 disposed rotationally forward are believed to be
advantageous because the
center section 102 for blades of such configurations fling chips forward,
which is believed to be
more appropriate for most situations.
Each of the blade profiles discussed herein is considered to be a stepped
blade profile
with at least one section of the profile being disposed parallel to the drum's
longitudinal axis 86.
A stepped blade profile has a rotationally forward face formed of adjacent
sections that are
non-collinear, with joining sections (disposed generally transverse to axis
86) connecting the
neighboring sections of the forward face. Typically, the neighboring sections
are offset from
each other in the rotational direction. Further, the stepped profiles
typically have at least two of
the sections disposed parallel to one another (sometimes collinear), but this
is not required as
seen in Fig. 10. In contrast, the blade profiles shown in Figure 4 of U.S.
Patent No. 6,811,120,
and Figure 3 and Figure 4 of U.S. Patent No. 6,948,610, are not considered to
be stepped, as
that term is used herein.
The handling device 20 may be used to load wood chips, and particularly
uniformly-sized
paper making wood chips, into a pile, either on the ground or in a suitable
container.
Representative examples of suitable containers include railcars 12, ships,
barges, trailers,
storage bins, and process containers such as digestion chambers. Using a
railcar 12 as an
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CA 02610190 2007-11-13
illustrative example of a container, the device 20 is mounted to the tower 16
of the loading
station 10. The railcar 12 is positioned below the handling device 20, and
motor 24 is started to
start the drum 80 rotating. Before feeding wood chips to the device 20, the
drum 80 should be
rotating at a rate of approximately 50 rpm. When the drum 80 is spinning
properly, wood chips
supplied to the feed chute assembly 30 by the conveyor system 14, falling as
an input stream
200 to the drum 80. The wood chips fall to the drum 80 and are then flung by
the blades 100 of
the spinning drum 80. This relatively slow initial spin rate helps prevent the
wood chips leaving
the drum 80 from being flung into the space between railcars. The drum
rotational speed is
then increased to an higher level less than 350 rpm, such as approximately 120-
180 rpm. The
output stream of wood chips leaving the drum 80, when the drum 80 has the
blades 100 as
described above, flows both forward and rearward from the drum 80. Indeed, the
output stream
covers an arc G3 of typically 90 -120 , with the arc (3 measured at the
intersection of two lines: a
line tangent to the drum where the forwardmost-flung chip leaves the drum 80
and a line
tangent to the drum where the rearmost-flung chip leaves the drum 80. See Fig.
2. When
viewed from above, the output pattern of the wood chips advantageously has a
generally
rectangular or oval shape, with perhaps a slight variation towards the middle.
The wood chips
flung from the drum 80 are captured by, and form a pile in, the container 12.
Even with a generally rectangular or oval output pattern, there may be an
undesirable
side-to-side distribution of the wood chips within the output pattern. For
instance, the
distribution of wood chips in the output pattern to the middle subsector,
right side subsector, and
left side subsector may be uneven and/or otherwise undesirable for some reason
(e.g., output
shifted left of center, leaving right side subsector relatively unfilled). If
the optional variably
positioned dividers 46 are employed, then the ratio of output flow to the
various subsectors may
be adjusted by the operator during operation (via adjusting mechanism 48) to
reach the desired
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ratios. Adjustments can also be made to the drum 80 rotational speed and to
the wood chip
supply rate from the conveyor system 14.
In the discussion above, it has been assumed that the position of the
directing wall 60
relative to drum 80 is either permanently fixed or may be varied during non-
operational periods.
That is, the directing wall 60 may be moved from one position to another with
the drum 80 not
rotating, fixed in the new position, and then the drum 80 activated. Such an
arrangement is
believed suitable for most applications. However, in some embodiments, the
directing wall 60
may be dynamically adjusted during operation of the device 20. For example,
the side sections
64 of directing wall 60 may be pivotally mounted at their upper portions to
the center section 62,
making their lower portions moveable relative to the center section 62. The
movement of the
lower portions could then be controlled by suitable actuators, such as linear
drives,
spring/cables, auxiliary motors, or other known actuators. The lower portions
may then be
moved during operation of the device 20 so as adjust the output pattern. It is
believed that
movement of the directing wall sections closer to top dead center will have
the effect of moving
rotating the output pattern generated by those sections counter-clockwise
(assuming that the
drum is rotating clockwise), and that movement of the directing wall sections
away from top
dead center will have the opposite effect.
While the exact principles are not fully understood, the handling device 20 of
the present
invention is able to pack wood chips at density substantially higher than so-
called free-fall
loading. In free-fall loading, the wood chips from the conveyor system 14 are
directed to a pile,
in a container or otherwise, via a simple chute system. Examination of free-
fall loaded wood
chips "packed" in the pile show that they land with widely varying
orientations, sometimes
referred to as "jack strawed" (like unstacked firewood), resulting in non-
optimum density. In
CA 02610190 2007-11-13
contrast, the wood chips loaded via the present device 20 land with a
substantially consistent
orientation, resulting in increased density.
The actual packed density achieved is expected to vary depending on variations
in size
and moisture content of the wood chips, and possibly on rotational speed of
the drum 80.
However, a simple ratio, referred to herein as the packing density factor, can
be used to quantify
the improvement provided by the present invention. The packing density factor
is simply the
ratio of the weight of wood chips in a given volume when packed with the test
device 20 divided
by to the weight of the same volume of the same type wood chips (i.e., same
size and moisture
content), packed using the free-fall method. For instance, it is expected that
a common 7100 ft3
railcar loaded with wood chips using the free fall method will have
approximately seventy-seven
tons of wood chips. It is expected that if the same type wood chips are loaded
using the device
of the present invention, the 7100 ft3 railcar could hold approximately one
hundred tons of
wood chips. Using these values, the packing density factor for the present
invention would be
100/77 = 1.30. Clearly, substantial improvements in packing may be achieved
using the
15 present device 20, with resulting packing density factors in the range of
1.20 to 1.35 or higher.
For reference, these type of packing density factors typically correspond to
densities of 26.0
pounds/ft3 to 29.3 pounds/ft3 or more.
It should also be noted that most prior art devices which rely on a
distribution device that
spins about a generally vertical axis (e.g., of the type shown in U.S. Patent
Publication Number
20 2002/0076308) tend to create round output patterns covering substantially a
full 360 , which are
ill suited to filling rectangular containers. As the majority of wood chips
shipped between
domestic locations are shipped by rail, using rectangular railcars 12, the
preferred embodiments
of the present invention are more suited to the needs of the industry.
16
CA 02610190 2007-11-13
The densely packed output from the flinger 20 is useful in densely packing
wood chips in
a variety of containers, and even for stacking wood chips on the ground. For
example, many
wood pulp mills receive wood chips generated at other locations and then store
the wood chips
as inventory for subsequently making wood pulp. It is common for this
"inventory" of wood
chips to be stored in a pile on the ground, such as on rough cleared land or
on a concrete pad.
In the prior art, this inventory pile is typically formed by the wood chips
falling off the distal
moving end of an inclined boom, with the wood chips routed thereto by a
conveyor that runs
along the boom. The booms may be track-guided linear motion booms, or may be
rotating type
booms. In the former case, the resulting pile of wood chips is typically an
elongated mound; in
the later case, the resulting pile of wood chips has an arc or annular shape
when viewed from
above, as dictated by the rotating boom. In both cases, the resulting pile is
rather loosely
packed, as it is formed by a free-fall process, with densities generally in
the range of 19-23
pounds/ft3. The flinger 20 of the present invention may be used in such
situations to allow more
chips to be stored in the same space, by packing the chips with significantly
higher density
compared to the conventional free-fall technique, typically on the order of 25-
30 pounds/ft3.
Thus, the pile may be said to have a packing density factor of 1.20 or more,
and preferably a
packing density factor of 1.3 or more.
The discussion above has described a device 20 using a single rotating drum
80. In
most applications, this will be sufficient. However, the present invention is
not limited thereto,
and devices 20 employing a plurality of drums 80 rotating about one or more
generally
horizontal axes 86 are intended to be encompassed by the present invention.
The most likely
arrangement for such a multiple drum 80 arrangement would be to have the drums
80 located
coaxially, in a manner easily understood by one of ordinary skill in the art
based on the
teachings of the present application.
17
CA 02610190 2007-11-13
The increase in packing density readily achieved by the present invention has
clear
benefits to the industry. In the simplest terms, more wood chips can be packed
into a smaller
space, thereby lowering transportation, storage, and processing costs.
Further, given the
substantial increase in packing density achieved, the cost savings can be
considerable.
Under some circumstances, the additional packing density provided by use of
the
present flinger 20 may cause certain containers to be become overweight and/or
unbalanced.
For instance, railcars 12 packed using the flinger device 20 may be loaded
with wood chips to a
weight that is more than allowed. As such, the inventor has developed a method
of filling
containers, such as railcars 12, using the flinger device 20 that allows for
tighter control of the
filling process to avoid overfilling and/or undesirable unbalanced loading. In
the method, an
level sensor is used to sense the current fill level of the railcar 12 at a
predetermined location
relative to the flinger. For example, this predetermined location may be in a
location that is
above the top of railcar 12, below the flinger 20, and typically straight down
from the
forwardmost portion of drum 80, or slightly farther forward thereof. Various
type of fill sensors
may be used, such as optical, mechanical, or the like. However, optical
sensors, such laser or
LED based optical sensors, believed to be ideally suited. When the optical
sensor is either not
blocked, or is only intermittently blocked, then the filling process may
proceed. However, when
the sensor is blocked, this indicates that the filling process has reached a
desired level, and the
railcar is advanced to fill another portion of the railcar or another railcar.
The "cut-off' level may
be set based on weight measurements on a sample car, and may change depending
on the
moisture content of the wood chips, etc. If desired, the railcar 12 may be
further filled to the
desired volume level by filling with "loose-pack" material. Further, it may be
advantageous to
divert the flow of chips to the flinger 20 via the "pants leg" chute system
while the gap between
railcars 12 is in the chip flinging zone, so as to avoid unnecessary spillage
of the chips.
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CA 02610190 2007-11-13
As will be understood by one of ordinary skill in the art, the filling process
may be
manually controlled by an operator. Alternatively, as suitable electronic
controller, sensors, and
the like may be used.
One example of the handling device 20 of the present invention may be made
using a
drum 80 with a diameter of approximately thirty inches, approximately 48
inches in width, and
an octagonal cross-section of approximately seven inch wide facets 92. The
blades 100 may be
approximately six inches in height and spaced at intervals of approximately
seven inches. The
blade's center section 102 may be sixteen inches; the intermediate sections
104 eight inches,
and the end sections 106 also eight inches, with offset sections 108 of
approximate three and
one-half inches. The baseplate 42 of the feed chute assembly 30 may be at a
450 angle, with
the 24-30 inch high directing wall 60 positioned such that the center section
62 is approximately
five inches after top dead center and the side sections 64 are approximately
ten inches after top
dead center, for a gap between the directing wall 60 and the baseplate 42 of
approximately ten
to twelve inches. The extra length for the offset sections 66 may be two
inches. The vertical
gap between the drum and the directing wall may be'/2 to three inches, with a
smaller gap
believed to be more advantageous. The pivoting divider walls 46 may be made
adjustable, with
a target distribution of 25%-50%-25% for feeding to the left 84, center 82,
and right 84 portions
of the drum 80 respectively. The directing wall 60 and feed chute assembly 30
may be formed
of %4 inch stainless steel, with the other portions of the device 20
contacting the wood chips may
advantageously made from '/4 inch abrasion resistant (AR) steel, although
other materials
known in the art may serve equally well. The rotational speed of the drum 80
may, for example,
be on the order of 120-180 rpm.
19
CA 02610190 2007-11-13
The disclosures of U.S. Patent No. 6,811,020 and U.S. Patent Application
Serial Nos.
10/465,182, filed June 19, 2003, and 10/678,838, filed 3 October 2003, are
incorporated herein
by reference to the extent not inconsistent herewith.
While the invention has been illustrated and described in detail in the
drawings and
foregoing description, the same is to be considered as illustrative and not
restrictive in
character, it being understood that only some embodiments have been shown and
described
and that all changes and modifications that come within the meaning and
equivalency range of
the appended claims are intended to be embraced therein.
