Note: Descriptions are shown in the official language in which they were submitted.
CA 02513609 2005-07-18
WO 2004/064991 PCT/US2004/000791
-1-
IMPROVED PULPER ROTOR AND ASSEMBLY
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the priority benefit of U.S. Provisional
Patent Application 60/440,532 filed January 16, 2003.
BACKGROUND OF THE INVENTION
Field of Invention
[0002] This invention relates to an improved pulper or mixer rotor with
increased pumping and defibering capacities, reduced power requirements,
easier
maintenance and interchangeability of parts, and improved wear resistance.
Description of Related Art
[0003] Fig. 1 shows a conventional pulping, mixing, or defibering
apparatus, which generally includes a vat, or tub, 10 formed of side wall 11
and
bottom wall 12. In the center of the bottom wall 12 is a perforated bed-plate
13.
The bed-plate 13 permits draining of pulped paper stock, for example, after a
pulping operation is completed. A rotor 15 for circulating the paper stock,
for
example, or other material, is mounted on a hub 14 in the center of the bed-
plate
13. Supports 19 stabilize the pulping tub, or vat, 10.
[0004] The rotor 15 creates a mechanical shear and/or hydraulic shear effect
on the pulp, or other material, being mixed. Mechanical shear, for example, is
achieved by rotating the rotor 15 above the stationary bed-plate 13 so that
the paper
pulp stock, or other material, is agitated, and the fibers and liquids are
approximately separated by being strained through the bed-plate 13 under the
pressure applied by vanes 17 of the rotor 15. Hydraulic shear, on the other
hand,
occurs by contacting the paper pulp fibers, for example, with other paper pulp
fibers
in the tub, or vat, 10 as a result of the turbulence, or flow pattern,
generated by
rotation of the rotor 15. The rotor 15 is driven by gears that engage the hub
14. A
motor 22 powers the gears that are housed within gear housing 20.
CA 02513609 2005-07-18
WO 2004/064991 PCT/US2004/000791
[0005] Fig. 2 shows a conventional pulper rotor 15 with a series of straight
vanes 17 extending beyond the outer circumference of a spar ring 16. The
straight
vanes 17 tend to be fairly blunt and thick at a leading vane face 17a, and
tapers
thinner at a trailing edge 17b of each vane 17. One end of each vane 17
nearest the
spar ring 16 joins an outer portion of the spar ring 16. The portions where
each
vane 17 joins the spar ring 16 gradually tapers to form a gulley 17c. These
gulleys
17c are susceptible to cavitation wear from the turbulent flow of pulp, or
other
materials passing over the vanes 17 in the wake of the agitation generated by
rotation of the rotor 15.
[0006] Fig. 3 shows that straight vanes 17 result in an angle of the leading
edge of the vane face 17a varying relative to a radian rn, for example,
projecting
from the rotor hub 14 to the edge of the vane face 17a. As seen in Fig. 3, for
example, the angle of the vane face 17a at a location nearest the spar ring 16
is 43
degrees relative to a radian r~ projecting from the rotor hub 14 to a first
edge
location of the vane face 17a, whereas the angle of the same vane face 17a at
an
edge location furthest from the spar ring 16 is 30 degrees relative to a
radian r2
similarly projecting from the rotor hub 14 to the edge of the vane face 17a.
As a
result of the change in angle of the vane face 17a, the vane face 17a strikes
the pulp
material, or other material being mixed, less consistently and with less
mixing or
agitation effect because the relative angle of the vane face 17a lessens as
the vane 17
extends further from the spar ring 16. That is to say, the pulp material, or
other
material being mixed by the vane 17 by striking the vane face 17a, is less
likely to
be mixed with the same consistency or force by the straight vane 17 as the
rotation
of the rotor 15 occurs because the lessening relative angle of the vane face
17a
encourages the materials being mixed to simply slide along the vane face 17a
of
each vane 17 and outward from the rotary path of the vanes 17. Thus, the pulp,
or
other material being mixed, in conventional straight vane rotor systems tend
to be
ineffectively directed out of contact with the vane faces 17a and out of the
rotary
path of vanes 17, resulting in a more time-consuming mixing of the materials
being
required in order to achieve a desired defibering, for example, effect. The
additional mixing time due to the inefficiencies of straight vane rotors
requires
CA 02513609 2005-07-18
WO 2004/064991 PCT/US2004/000791
-3-
additional power consumption to operate the rotor until the desired defibering
effect
on the materials is achieved.
[0007] Further, the bluntness of the leading edge of straight vane face 17a
subjects the vane faces 17a to considerable wear as mixing of materials
occurs. To
compensate for the wear induced by the agitation of materials on the leading
edge of
straight vane faces 17a, prefabricated wear plates are often separately welded
onto
the leading edge of the vanes 17. Such straight vane face pulper rotors 15
with
welded wear plates may be relatively easy to make, however, they tend to have
some of the same inefficiencies at pumping materials in desired directions or
capacities due, at least partially, to the changing relative angle of contact
of each
vane face 17a with the pulp, or materials, being mixed as discussed above.
Further,
the requirement of welding wear plates onto the vanes 17 limits the materials
that
can be used to those compatible with the underlying material chosen for the
vane.
Such compatibility requirements may limit the choice of vane materials to
those that
are generally not the most wear-resistant type materials in order for the wear
plates
to be successfully welded onto the vanes. Still further, because of the
welding
aspect of the wear plate, it is often required to change the entire vane, at
least, even
when only the wear plate is all that is worn.
[0008] Moreover, straight vane face rotors can be difficult and economically
inefficient to repair, replace or maintain. For example, often removal of the
entire
rotor is required in order to replace, repair or service just a vane or just a
wear
plate. The removal of an entire rotor may require additional personnel, and
may
result in significant inoperable time of the pulper, or mixer, in general.
[0009] To address the inefficiencies of straight vane face rotors, booster
vanes 18, as shown in Fig. 2, are frequently used. Such booster vanes 18 are
also
typically welded to the top of the straight vanes 17 to add an additional
material
contacting face and to increase pumping efficiencies. The use of booster vanes
18
still does not render straight vane face rotors optimally efficient however,
as the
additional materials and production costs render such straight vane rotors 15
with
booster vanes 18 more costly to manufacture. Further, even with booster vanes
18,
some materials are already directed away from the vanes 17, in general, by the
CA 02513609 2005-07-18
WO 2004/064991 PCT/US2004/000791
-4-
material's initial impact with the straight vane face 17a as discussed above.
Such
booster vanes 18 also require increased power requirements to achieve
increased
pumping capacities. Thus, any pumping efficiency added by the booster vanes 18
may well be offset by the added manufacturing and added operational costs
incurred
with straight vane rotors having booster vanes 18. Further, the introduction
of yet
another additional part, represented by the booster vane 18, increases the
costs and
time required for maintenance, repair and/or replacement, while still
experiencing
the inconvenience of having to remove the entire rotor 15 to perform such
repair,
replacement or maintenance functions. Further still, such booster vanes 18
result in
the gulleys 17c being particularly susceptible to cavitation wear as a result
of the
increased turbulence of materials flowing in the wake of the booster vane 18
induced agitation of the pulp stock, or other material, being mixed.
[0010] As with the inefficiencies experienced by the changing angle of the
vane face relative to the series of radians rn projecting from the rotor hub
14,
straight vanes 17 also have a varying intersection angle relative to the
underlying
bedplate 13 of the conventional pulper rotor 15. The interface of the pulp
stock, or
other material, agitated by the vanes 17 of the rotor 15 and pressed downward
toward the bedplate 13 results in the desired defibering, for example, of the
pulp, or
other materials, as the liquefied matter passes, as if strained, through
apertures 13a
of the bedplate 13 (see Fig. 4). (Thus, because the intersection angle of the
vanes
17, relative to the bedplate 13, changes as the vanes 17 extend across the
bedplate
13, the pressure imposed upon the pulp stock, or other material, from the
vanes 17
is not consistently applied to the materials from the inner diameter to the
outer
diameter of the bedplate 13. As a result, defibering efficiency is less than
optimal.
[0011] The inefficiencies of such straight vane rotors with respect to
pumping and defibering inefficiencies, even with booster vanes, and the
susceptibility of straight vane rotors to high wear zones and maintenance,
repair or
replacement inconveniences, pose problems the improved pulper, or mixer rotor,
as
set forth herein, is designed to help overcome. Further the power consumption
inefficiencies of straight vane rotors may be minimized by the improved
pulper, or
CA 02513609 2005-07-18
WO 2004/064991 PCT/US2004/000791
-5-
mixer rotor described herein which helps eliminate the need for such booster
vanes,
and performs similar mixing of materials in less time, while requiring less
power.
SUMMARY OF THE INVENTION
[0012] This invention provides an improved pulper, mixer or defibering,
rotor having a spar ring attached to a hub of the rotor with a series of
curved vanes
projecting from the spar ring. The curved vanes have a constant vane face
angle
relative to radians immediately adjacent one another and extending outward
from the
hub of the rotor. As a result of the constant relative vane face angle, the
pulp, or
materials, mixed by the vanes of the rotor are more consistently in contact
with the
vanes during rotation of the rotor. Thus, booster vanes are not required. As a
result, increased circulation and pumping effects with minimal power
requirements
are achieved.
[0013] This invention separately provides a series of curved vanes having
vane faces with substantially similar, or preferably equal, surface volumes.
As a
result of the substantially similar, or preferably equal, vane face surface
volumes,
the paper pulp stock, or other materials, being mixed by the vanes in the
pulper tub,
or vat, remains in contact with the vane face of each vane for a prolonged
period as
circulation occurs.
[0014] This invention separately provides the series of curved vanes
projecting from the spar ring as separately attachable to the spar ring via
spar stubs.
The spar stubs are made of a high strength material integral with the spar
ring,
whereas the separably attachable vanes are made with a highly wear-resistant
material. As a result of the separably attachable nature of the vanes to the
spar
stubs, maintenance is easier as the vanes may be repaired or replaced without
requiring removal of the entire rotor. Further because the vanes are separably
attached, rather than welded, a greater variety of highly wear-resistant
materials are
available to form the vanes. As a result of the high strength spar ring and
spar
stubs, the need for additionally welded wear plates and/or booster vanes are
not
required, thus minimizing weight and power consumption. As a result of the
highly
wear-resistant material, the circulation and pumping effectiveness of the
vanes and
CA 02513609 2005-07-18
WO 2004/064991 PCT/US2004/000791
-6-
rotor continue longer, reducing the need for repair or replacement. As a
further
result of the separably attachable vanes, the opportunity to change
configurations of
the vanes to meet changing customer needs is also more readily available.
[0015] This invention separately provides vanes having an endplate feature
that improve the tip suction pulse effect, which recirculates the paper pulp
stock, or
other material, more easily in the pulper tub, or vat, until the desired
defibering, for
example, is achieved.
[0016] These and other features and advantages of this invention area
described in, or are apparent from, the following detailed description of
various
exemplary embodiments of the systems and methods according to this invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Various exemplary embodiments of the systems and methods of this
invention will be described in detail with reference to the following figures,
wherein:
[0018] Fig. 1 illustrates a conventional pulper;
[0019] Fig. 2 illustrates a conventional straight vane faced rotor with
booster vanes;
[0020] Fig. 3 illustrates a vane face angle of a conventional straight vane
faced rotor relative to a radian originating from a rotor hub;
[0021] Fig. 4 illustrates an improved rotor mounted above a perforated bed-
plate according to at least one exemplary embodiment of the invention;
[0022] Fig. 5 illustrates a bottom view of an exemplary embodiment of an
improved rotor according to the invention;
[0023] Fig. 6 illustrates another embodiment showing a different mounting
of the vane to a spar ring;
[0024] Fig. 7 illustrates an exemplary embodiment of a single vane
according to the invention;
[0025] Fig. ~ illustrates a vane face angle of the improved rotor referred to
in Fig. 4 relative to a radian originating from the rotor hub;
CA 02513609 2005-07-18
WO 2004/064991 PCT/US2004/000791
-7_
[0026] Fig. 9 illustrates another exemplary embodiment of a spar stub and
vane according to the invention;
[0027] Fig. 10 is a schematic view of a composite vane in accordance with
another embodiment of the invention; and
[0028] Fig. 11~ is a schematic view of another vane structure.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0029] The conventional pulper tub, or vat, 10 shown in Fig. 1 shows
generally the type of pulper tub, or vat, 10 with which the various exemplary
embodiments of the improved pulper, mixing or defibering, rotor 35 of the
invention described herein is intended to be used. Accordingly, like numerals
are
used, where possible, in describing the various exemplary embodiments of the
invention when referring to features translatable with those of the
conventional
pulper of Fig. 1.
[0030] Fig. 4 shows one exemplary embodiment of the improved pulper,
mixer or defibering, rotor 35 of the invention. The pulper, mixer or
defibering,
rotor 35 includes a spar ring 36 that supports a plurality of vanes 37. The
vanes 37
extend generally radially outwardly from the spar ring 36 towards an outer
circumference of the perforated bed-plate 13. The spar ring 36 is mounted
about a
hub 14 at the center of the bed-plate 13. The pulper, mixer or defibering,
rotor 35
may be driven by a conventional gearing and motor 22 combination, as generally
depicted in Fig. 1. Rotation of the vanes 37 of the pulper, mixer or
defibering,
rotor causes paper pulp stock, for example, or other material, to circulate in
the tub,
or vat, 10. The circulation of the stock, or other materials, helps achieve
the
hydraulic shearing effect among the circulating stock, or other materials, as
well as
the mechanical shearing effect on the stock, or other materials, via the
interaction of
the rotating vanes 37 against the stationary bed-plate 13 at a bottom of the
pulper
tub, or vat, 10. Once the fibers of the paper pulp stock, or other material,
are
sufficiently broken down, or defibered, for example, the materials pass
through
apertures 13a of the bed-plate 13.
CA 02513609 2005-07-18
WO 2004/064991 PCT/US2004/000791
_g_
[0031] Fig. 5 illustrates the underside of an exemplary embodiment of the
pulper, mixer or defibering, rotor 35. The vanes 37 are demountably attachable
to
spar stubs 38 extending from the spar ring 36. The spar stubs 38 may be made
integrally with the spar ring 36 as shown in Fig. 5. Alternatively, the spar
stubs 38
may be separably attached, for example welded, to the spar ring 36 as shown in
Fig.
4. In any event, the spar stubs 38 project, at designated intervals, from an
outer
circumference of the spar ring 36. The spar stubs 38 may be made of the same
material as the spar ring 36, or of a different material, in order to provide
similar
strength and a high degree stability between the spar stubs 38 and spar ring
36.
[0032] The spar stubs 38, of the exemplary embodiment shown in Fig. 5,
include attachment devices 39 for securing the vanes 37 to the spar stubs 38.
The
attachment devices may be any of screws, rivets, projections, or other such
structures for securing the vanes 37 to the spar stubs 38. It is noted that
those
skilled in the art may fashion other coupling arrangements besides the
projection/spar stubs 38 that may be received in female grooves or the like
shown.
For example, the vanes 37 could be designed to have male projections on their
i.d.
ends adapted for receipt in female concavities provided in appropriate
locations on
the spar ring 36. One such alternative coupling design is shown in Figure 6.
Here,
specifically configured female slots 100 are provided around the periphery of
spar
ring 36. Mating male ends 102 of the vanes 37 are snugly fitted in the slots
and the
joint can be further secured by bolts or the like (not shown) that would be
inserted
through registered bores 104, 106 placed respectively in the female and male
parts,
and corresponding apertures 108 of the clamp ring 110. A rotor cap 112 is
attached
over the assembly to secure to the clamp ring.
[0033] Fig. 7 illustrates an exemplary embodiment of a vane 37. The vane
37 is reparably attachable to the spar stubs by attachment devices 40
corresponding
to the attachment devices of the spar stubs. Each vane 37 includes a vane face
37a
on the leading edge, a trailing edge 37b and a spar stub mounting surface 37c.
The
vane face 37a is provided with a designated vane height hl. The vane height hl
at
the vane face 37a tapers to a vane height h2 at the trailing edge 37b of the
vane 37.
The pitch angle of the vane face 37a is preferably constant, for example at
30°, to
CA 02513609 2005-07-18
WO 2004/064991 PCT/US2004/000791
-9_
provide a desired pressure to the paper pulp stock, or other materials, being
mixed
by contact with the vane face 37a of the vane 37 upon rotation. The vane 37
may
be slid onto the spar stub 38 (see Fig. 5) in order to align the spar stub
mounting
surface 37c of the vane 37 so that the corresponding attachment devices are
aligned
to secure the vane 37 to the spar stub 38, and the innermost vane surface 37d
abuts
the spar ring 36 (Fig. 4). The outermost vane surface 37e of the vane 37 is
generally curved from the vane face 37a to the trailing edge 37b. The
interface of
the trailing edge 37b and outermost vane surface 37e of the vane 37 provides a
lifting effect that sucks fiber off from the stock, or other materials, being
mixed by
rotation of the rotor 35. Note also in Fig. 7 that the trailing edge of the
vane
comprises a curved edge 116 radiused downwardly toward the bed-plate surface.
This too helps to provide a suction pulse that cleans the bed-plate. Further
protruding end dam member 114 is provided along the o.d. extremity of the
trailing
edge. The end dam doesn't allow flow to "leak" off the end of the rotor;
thereby
improving suction and bed-plate cleaning across the entire swept area.
[0034] Fig. 8 shows generally, according to the various exemplary
embodiments of the invention, a configuration of the vanes 37 mounted to the
spar
ring 36 by attachment devices 40. The vanes 37 are mounted such that the angle
between the vane face 37a and a radian r~ extending from the center of the hub
14
towards the outermost circumference of the spar ring 36 is substantially the
same as
the angle between the vane face 37a and any other radian, for example rz,
similarly
extending from the center of the hub 14 and toward the outermost circumference
of
the spar ring 36 or the outermost vane surface 37e. By substantially the same
we
mean that the difference in vane face surface to intersecting radian angle for
any two
points along the vane face surface should not exceed greater than about
10°. By
controlling the angle of the vane face 37a relative to the spar ring 36, more
constant
contact of the paper pulp stock, or other materials, being mixed is achieved
upon
rotation of the rotor 35 and vanes 37. Further, because the vanes 37 may be
separably attached to the spar ring 36 by mounting to the spar stubs 38 (Fig.
5), the
vanes 37 may be made of a greater variety of materials, such as ceramics,
CA 02513609 2005-07-18
WO 2004/064991 PCT/US2004/000791
-10-
urethanes, or other highly wear resistant and durable materials that previous
straight
vane faced rotors, for example, were not able to be made of.
[0035] Of course, it should be appreciated that the angles of each of the
vane faces 37a are not limited to uniformity, rather, the angle of the vane
face 37a
of each vane may be varied to accomplish the desired contact with the stock,
or
other materials, being mixed. Likewise, the contour or shape of the vanes 37
may
be varied even though mounted on the same spar ring 36, such that one vane 37
may
be smooth, and another vane 37 may be toothed, for example, or otherwise not
smooth, in order to achieve different pulping, mixing or defibering, actions.
Similarly, vanes 37 of different lengths may be mounted on the same spar ring
36 to
achieve different pulping, mixing or defibering, actions as well.
[0036] Certain advantages of the various exemplary embodiments of the
rotor 35 using the reparably mounted vanes 37 of the invention versus
standard, or
conventional, rotors may occur. For example, the various exemplary embodiments
of the rotor 35 and vanes 37 will achieve the same thrust (Th) using
significantly
less horsepower (hp) than standard, or conventional, rotors. As a result, not
only
will more stock, or other materials, be in contact with the vane face 37a of
the
vanes 37, as described with reference to Fig. 7, for example, but the
efficiency of
the pulping, mixing or defibering will be increased as well while less power
will be
used as evidenced by higher thrust/horsepower ratios (Th/hp) than conventional
designs. Additionally, a greater volume, or quantity, of stock, or other
materials,
may be pulped, mixed or defibered per unit time (sec) as would be evidenced by
the
quantity to time ratio (Q) .
[0037] Thus, not only are the various exemplary embodiments of the
separably attached vanes more efficient, they also are more durable and wear
resistant due to the choice of materials available to comprise each vane 37.
Moreover, even were replacement or repair of the vanes 37 required, such
replacement or repair is relatively easy as the rotor 35 may be left in the
pulper tub,
or vat, 10, for example, whereas prior art conventional rotors require the
complete
removal of the rotor in order to work only on the vanes, or other vane related
components, for example.
CA 02513609 2005-07-18
WO 2004/064991 PCT/US2004/000791
-11-
[003] Fig. 9 illustrates another exemplary embodiment of the vanes 47
according to the invention. The vanes 47, according to the exemplary
embodiment
shown in Fig. 10 differ from the vanes 37 shown in Fig. 7, which illustrate
vanes 37
having a continuous trailing edge 37b extending from the innermost vane
surface
37d to the outermost vane surface 37e and integral with each vane 37. As a
result,
the vanes 37 are mounted by sliding over the spar stubs 38, in a generally
perpendicular direction relative to the spar ring 36, towards the spar ring
36. The
exemplary embodiment of the vanes 47 shown in Fig. 9, on the other hand,
provides
spar stubs 48 joined at one end to the spar ring 36 and having an outer end
48a
opposite the spar ring 36. Each spar stub includes a first trailing edge
portion 48b
extending from the spar ring 36 to an outer end 48a of the spar stub 48.
[0039] A vane 47 having a vane face 47a and a second trailing edge portion
47b is slidingly mounted over each spar stub 48, in a generally lateral
direction
relative to the spar ring 36, such that the first trailing edge portion 48b of
the spar
stub 48, and the second trailing edge portion 47b of the vane 47, are
immediately
adjacent one another to form the equivalent of the unified trailing edge 37b
of the
exemplary embodiment described with reference to Fig. 7 above. Once aligned
appropriately over the spar stub 48, the vane 47 is attached to the spar stub
48 in a
manner as described with reference to the exemplary embodiments discussed
above.
[0040] The vanes 47 of the exemplary embodiment illustrated in Fig. 9 have
vane faces 47a of a constant pitch angle such that the stock, or other
materials,
being mixed are more readily contacted by the vane face 47a as the rotor 35
and
vanes 47 rotate. Likewise, the vane 47 tapers from a height hl at the vane
face 47a
to a height h2 at the combined trailing edge formed of first trailing edge
portion 48b
and second trailing edge portion 47b.
[0041] The vanes 47 thus provide similar advantages to those described with
reference to the exemplary embodiments discussed above. Such advantages
include
the greater choice of materials to form the vanes 47, more flexibility in the
arrangement of vanes 47 on the spar ring 36, greater contact area and contact
time
of the materials being mixed with the vane face 47a, decreased power
requirements,
and easier accessibility for maintenance and repair of the vanes 47.
CA 02513609 2005-07-18
WO 2004/064991 PCT/US2004/000791
-12-
[0042] An alternative vane structure is shown in Fig. 10. Here, the face
37a of the vane comprises a wear plate 118 made of a hard metal that is, for
example, investment cast to the desired shape. The trailing body section 214
of the
vane may be formed from a filler/bonding material. As shown, spar stub 38 is
partially in phantom and includes a male mounting end 116 adapted for
reception in
a female recess or the like in the spar ring (not shown). The body section 214
may
hold the face plate and spar stub 38 together and provide the required
hydraulic
profile. Body section 214 may be composed of an urethane/epoxy but could also
be
a bi-metal cast process.
[0043] Fig. 11 illustrates another unique aspect of the invention. Here, the
id. surface of the vane is shown at 140 with the o.d. surface depicted as 142.
One
inner length of the vane shown at 150 is shorter than an outer vane length
shown at
152. The vane length in this embodiment increases progressively from inner
vane
location toward outer vane location. In operation, this vane length/section
increases
as the peripheral shield of the vane location increases to improve performance
and
reduce drag.
[0044] It is apparent that the vane member shown in Fig. 11 is streamlined
to enhance operational performance. The vane member is adapted for radial
disposition on a hub or the like in a pulp and paper apparatus. The vane
member is
rotatable around a central axis that extends through the hub and the vane has
an
inner-end adapted for positioning adjacent to the hub at an opposing outer
edge at an
outer radially directed extremity of the vane. The vane comprises a leading
edge
190 and a trailing edge 192. The vane lengths are shown at 150 and 152 and
they
are defined as the distance between the leading edge and the trailing edge at
given
points along a continuum 160 that extends in the radial direction from the
inner-end
of the vane to the outer-end. In accordance with this aspect of the invention,
the
vane length increases as one proceeds along the continuum from the inner-end
to the
outer-end.
[0045] In operation, with any of the exemplary embodiments of the
improved pulper, or mixer, rotor 35 described herein, including the spar ring
36,
spar stubs 38 or 48, and vanes 37 or 47, paper pulp stock, or other material,
is
CA 02513609 2005-07-18
WO 2004/064991 PCT/US2004/000791
-13-
placed into the pulper tub, or vat, 10. The motor 22 is then operated to drive
the
gear 20. The gear 20 engages the hub 14, to which rotor 35 is mounted. The
rotation of the rotor 35 therefore causes the vanes 37 or 47 to rotate in a
direction
such that the vane face 37a or 47a contacts the stock, or materials,
initially. As
rotation of the rotor 35 and vanes 37a or 47a occurs, more consistent contact
of the
stock, or materials, with the vane face 37a or 47a is maintained resulting in
increased agitation and mixing of the materials. In addition, the trailing
edge 37b,
or the combined first trailing edge portion 48b of the spar stub 48 with the
second
trailing edge portion 47b of the vane, helps lift fibers, for example, from
the stock,
or materials, being mixed such that defibering is achieved. The defibered
materials,
for example, are then passed through the apertures 13a (Fig. 4) in the bed-
plate 13
underlying the rotor 35 at the bottom of the tub, or vat, 10.
[0046] In summary, one aspect of the invention is directed toward the
combination of demountable vane members that are adapted to be mounted over
and
carried by the spar stubs with the spar stubs being fixed to the annular spar
ring by
welding or the like. The demountable vanes may be composed of any one or more
of a variety of wear resistant materials such as for example, wear resistant
initial
such as "stellite", cast cobalt alloys, polyurethanes, even ceramic materials.
[0047] In another aspect of the invention, each of the leading surfaces of the
vanes presents a substantially constant angle relative to at least two radians
that
extend from the rotor axis to any two points located along that leading cage.
By
"substantially constant", we mean that this angle should not vary by more than
about 10°. It is generally desirable than this angle, as measured
between the axis
and to a point or tangent along the leading edge should be between about
10° to
about 60°, preferably about 30° to about 40°. In many
cases, it will be
advantageous if each of the vanes (and their corresponding leading edges)
possesses
this same leading edge angle.
[0048] While the invention has been described with reference to the
exemplary embodiments set forth herein, it should be appreciated that other
alternatives, combinations, modifications and variations are apparent to those
skilled
in the art. Accordingly, the preferred embodiments of this invention, as set
forth
CA 02513609 2005-07-18
WO 2004/064991 PCT/US2004/000791
-14-
above, are intended to be illustrative only, and not limiting. Various changes
can be
made without departing from the spirit and scope of this invention.
[0049] What is claimed is:
