U.S. patent application number 16/280718 was filed with the patent office on 2019-08-29 for cleaning notches and passages for a feeding or refining element.
The applicant listed for this patent is Andritz Inc.. Invention is credited to Luc Gingras, Tobias Michel.
Application Number | 20190264389 16/280718 |
Document ID | / |
Family ID | 67683860 |
Filed Date | 2019-08-29 |
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United States Patent
Application |
20190264389 |
Kind Code |
A1 |
Gingras; Luc ; et
al. |
August 29, 2019 |
CLEANING NOTCHES AND PASSAGES FOR A FEEDING OR REFINING ELEMENT
Abstract
A flinger or refiner plate for a mechanical refiner including
deep notches or holes in feeder bars of the flinger plate and/or
open passages or holes in bars of the refiner plate. The open
passages and/or holes in the bars significantly reduce stagnate
flow zones at the trailing side of the bars during operation of the
mechanical refiner. The reduction of the stagnate flow zones may
reduce or eliminate fiber accumulation at the trailing side of the
bars.
Inventors: |
Gingras; Luc; (Harrogate,
GB) ; Michel; Tobias; (Werbachhausen, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Andritz Inc. |
Glens Falls |
NY |
US |
|
|
Family ID: |
67683860 |
Appl. No.: |
16/280718 |
Filed: |
February 20, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62635143 |
Feb 26, 2018 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
D21D 1/306 20130101 |
International
Class: |
D21D 1/30 20060101
D21D001/30 |
Claims
1. A mechanical refiner flinger plate comprising: a front face; a
back face; a substrate separating the front face from the back
face; a center hub extending from the front face; feeder bars
extending from the front face, wherein the feeder bars extend
radially outward from the center; and a deep notch or hole disposed
in a feeder bar of the feeder bars, wherein the feeder bar has an
area defining the deep notch or hole, and the deep notch or hole
extends through the feeder bar and is configured to allow fluid to
pass through the feeder bar.
2. The mechanical refiner flinger plate of claim 1, wherein the
feeding bar further comprises a leading side and a trailing side
distally disposed from the leading side, wherein the deep notch or
hole further comprises a first end distally disposed from a second
end, and wherein the first end is disposed radially outward from
the second end.
3. The mechanical refiner flinger plate of claim 1, wherein the
deep notch or hole includes multiple deep notches or holes disposed
in the feeder bar.
4. The mechanical refiner flinger plate of claim 1, wherein the
deep notch or hole is disposed in each of the feeder bars.
5. The mechanical refiner flinger plate of claim 1, wherein the
deep notch or hole includes multiple deep notches and/or holes, at
least one of which is disposed in each of the feeder bars.
6. The mechanical refiner flinger plate of claim 1, wherein the
deep notch or hole further comprises a radially outermost edge at
the first end of the deep notch or hole, wherein the radially
outermost edge forms an obtuse angle between the adjacent notch or
hole sidewall and the leading side of the feeder bar.
7. The mechanical refiner flinger plate of claim 1, wherein the
deep notch or hole further comprises a radially outermost edge at
the first end of the deep notch or hole, wherein the radially
outermost edge is selected from a group consisting of a chamfer, a
bevel, and a curve.
8. The mechanical flinger plate of claim 1, wherein the notch
extends through the feeding bar and partially into the substrate,
or the hole is partially embedded in the substrate.
9. A mechanical refiner plate segment comprising: a substrate
having a radially inward edge and a radially outward edge; a
refining surface including bars separated by grooves wherein the
bars and grooves extend towards the radially outward edge; dams in
the grooves, wherein the dams in each groove span between the
adjacent bars on opposite sides of the groove; and at least one
open passage extending through one of the adjacent bars, wherein
the open passage has one end adjacent a trailing side of one of the
dams in the groove.
10. The mechanical refiner plate segment of claim 9, wherein the
open passage has a cross sectional area of at least nine (9)
mm.sup.2 for an entirety of a length of the open passage.
11. The mechanical refiner plate of claim 9, wherein the open
passage is separated from a ridge of the one of the adjacent bars
by at least 10%, or 15%, or 25% of the height of the one of the
adjacent bars.
12. The mechanical refiner plate segment of claim 9, wherein the
bars and grooves extend from one side edge of the substrate to an
opposite side edge of the substrate.
13. The mechanical refiner plate segment of claim 9, wherein there
is one of the open passages associated with at least 50% of the
dams in the refiner plate segment.
14. The mechanical refiner plate segment of claim 9, wherein the
refiner plate segment is formed of a cast metal.
15. The mechanical refiner plate segment of claim 9, wherein the
refiner plate segment has a pie-shape and is configured to be
arranged with additional refiner plate segments to form an annular
refiner plate.
16. The mechanical refiner plate segment of claim 9, wherein the
refiner plate segment is a portion of an annular refiner plate.
17. The mechanical refiner plate segment of claim 9, wherein the
radially inward edge is configured to be adjacent an outer
periphery of a flinger plate.
18. The mechanical refiner plate segment of claim 9, wherein the at
least one open passage is at least partially embedded in the
substrate below the one of the adjacent bars.
Description
RELATED APPLICATION
[0001] This application claims priority to U.S. Provisional Patent
Application 62/635,143 filed Feb. 26, 2018, which is incorporated
by reference in its entirety.
TECHNICAL FIELD
[0002] The invention relates generally to mechanical refiners and
more particularly to flinger and refiner plates in such refiners,
especially for pulping medium density fiberboard production and in
mechanical pulping systems.
BACKGROUND
[0003] Mechanical refiners convert into pulp wood chips, recycled
paper, recycled corrugated packaging material and other
lignocellulosic materials (collectively referred to as "feed
material"). The mechanical refiner applies pressure pulses,
shearing forces and other mechanical forces to separate the feed
material into separated fibers that form pulp. The feed material
may have a high consistency, such as over 30% dry contents. High
consistency cellulosic feed material may be refined to form medium
density fiberboard (MDF) or mechanical pulps such as
Thermo-Mechanical Pulp (TMP), Chemi-Thermo-Mechanical Pulp (CTMP)
and other variations of pulp.
[0004] As the feed material flows through the refiner, fibers and
extractives, such as resin, sap, pitch and other liquid or
liquefied wood components in the feed material, tend to accumulate
at certain locations in the refiner. These locations include the
trailing side of feeder bars on flinger plates and the trailing
side of dams between bars in refiner plates.
[0005] The accumulations of fiber and extractives become dark,
e.g., black, and hard. Occasionally, the accumulations dislodge
from the flinger and refiner plates, and enter the flow of feed
materials moving through the refiner. The dislodged accumulations
may break into small particles and mix into the flow of feed
material. The particles of accumulations form dark specs in the
pulp material output from the refiner and in the final product,
being paper or board. Pulp material with dark specs reduces the
final product's desirability and sales value. Accordingly, there is
a long felt need to reduce dark specs in the pulp material produced
by mechanical refiners.
SUMMARY
[0006] The inventors believe that the accumulations form due to low
pressure regions next to trailing surfaces on the flinger and
refiner plates. The low pressures are believed to cause stagnate
flow of the feed material in what otherwise is a fast flow of
materials through the refiner. Stagnate flow has low kinetic energy
and thus low total pressure, as compared to the total pressure of
fast flowing materials. Due to its low pressure, stagnate flow
traps material that would otherwise flow through the refiner. The
trapped material adheres to surfaces on the flinger and refiner
plates adjacent the stagnate flow. These surfaces tend to be
trailing surfaces of the bars of flinger plates, and trailing
surfaces near or on dams in grooves of a refiner plate. The
material remains trapped against the trailing surfaces and is
blackened by the heat in the refiner.
[0007] The inventors conceived of a solution to the accumulations
by increasing the pressures in stagnate flow regions. The pressure
can be increased by creating notches and/or holes in the bars of a
flinger plate and holes in the bars of a refiner plate. The notches
and holes extend from a leading edge of a bar to a trailing edge of
the bar. The notches and holes create a passage through the bar
between a high pressure region at the leading side of a bar and a
low pressure region at a trailing side of a bar.
[0008] The holes in the bars of a refiner plate open on a trailing
side of the bar just behind a dam connected to the bar. Pressurized
fluid, such as steam, flows through the holes to increase the
pressure of the stagnant flow. The increased pressure should add
energy to the stagnate flow regions and thereby reduce the tendency
of fibers and other materials to accumulate behind dams and on the
trailing sides of feeder bars.
[0009] The new designs of notches or holes in the bar of a flinger
plate and holes in the bars of a refiner plate should reduce the
low pressure that usually exists on the trailing side of feeder
bars and downstream of dams in grooves between refining bars. The
reduction in pressure differential may reduce or eliminate the
fiber accumulations that occur in conventional flinger and plate
designs by reducing or eliminating stagnate pressure zones.
[0010] An exemplary flinger plate or refiner plate in accordance
with the present disclosure comprises deep notches or holes in the
bars of the plate. The notches or holes in the bars allow steam to
flow from the high pressure leading side of the bar to the low
pressure trailing side of the bar.
[0011] The notches or holes in or through a bar of a flinger or
refiner plate may be oriented to reduce the fiber entrained with
the steam flowing through the notches or holes. To reduce the
fibers in the steam flowing through the bars, the notches or holes
may be aligned perpendicularly to the bars, or at an acute or
obtuse angle to the bars.
[0012] An exemplary flinger plate for a mechanical refiner may
comprise: a front face, a back face, a substrate separating the
front face from the back face, a center hub extending from the
front face, feeder bars extending from the front face, wherein the
feeder bars extend radially outward along the front face from the
center, a deep notch or hole disposed in a feeder bar of the feeder
bars. The deep notch or hole extends through the bar and is
configured to allow fluid to flow through the bar. The deep notch
or hole may be oriented to reduce the likelihood that fiber will
travel through the deep notch when the flinger plate is used in a
mechanical refiner.
[0013] The notch may have an opening at a leading side of the
feeder bar or refiner bar that has a cross-sectional area which is
smaller than a cross-sectional area of an outlet of the notch at
the trailing side of the bar. Similarly, the cross-sectional area
of the notch may gradually increase from the inlet to the outlet of
the notch. Similarly, hole(s) in each bar may have an opening at a
leading side of the bar that has a cross-sectional area smaller
than a cross-sectional area of an outlet of the hole at the
trailing side of the bar. The cross-sectional area of the hole may
gradually increase from the inlet to the outlet of the hole. The
holes may be an alternative to the notches or used in addition to
the notches. For example, notches may be in bars on a flinger plate
and holes may be bars on a refiner plate in the same refiner.
[0014] A mechanical refiner plate segment has been conceived and is
disclosed herein which includes: a substrate having a radially
inward edge and a radially outward edge; a refining surface
including bars separated by grooves, wherein the bars and grooves
extend towards the radially outward edge; dams in the grooves,
wherein the dams in each groove span between the adjacent bars on
opposite sides of the groove; and at least one open passage
extending through one of the adjacent bars, wherein the open
passage has one end adjacent or near a trailing side of one of the
dams in the groove.
[0015] The mechanical refiner plate segment may have an open
passage with a cross sectional area of at least nine (9) mm.sup.2
for an entirety of a length of the open passage. The open passage
may be below a ridge of the one of the adjacent bars by at least
10%, or 15%, or 25% of the height of the one of the adjacent bars.
The open passage may have an inlet at a leading side of the refiner
bar that has a cross-sectional area smaller than a cross-sectional
area of an outlet of the passage at the trailing side of the bar.
Similarly, the cross-sectional area of the open passage may
gradually increase from the inlet to the outlet. Also, there may be
an open passage associated with each of the dams in the refiner
plate segment.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The foregoing will be apparent from the following more
particular description of exemplary embodiments of the disclosure,
as illustrated in the accompanying drawings. The drawings are not
necessarily to scale, with emphasis instead being placed upon
illustrating the disclosed embodiments.
[0017] FIG. 1 is a cross sectional schematic drawing of a portion
of a mechanical refiner machine for pulping cellulosic feed
material.
[0018] FIG. 2 shows a front face of a flinger plate.
[0019] FIG. 3 is a cross-sectional view of the flinger plate shown
in FIG. 2 taken along the line 3-3 in FIG. 1.
[0020] FIG. 4 is a front view of a refiner plate segment.
[0021] FIG. 5 is side view of a portion of a cross section of the
refiner plate segment shown in FIG. 4.
DETAILED DESCRIPTION
[0022] FIG. 1 shows in cross section a conventional single-disc
refiner 10 having a housing 12 defining an internal chamber 14. A
rotor disc assembly 16 in the chamber is turned by a shaft 18
driven by a motor. The rotor disc assembly includes a supporting
disc 20, a circular flinger plate 22 attached to a front face of
the supporting disc 20, and an annular assembly of pie-shaped
refiner plate segments 24 mounted to the front face of the
supporting disc 20. Inner edges of the refiner plate segments are
adjacent an outer periphery of the flinger plate 22.
[0023] A similar annular array of plate segments 26 is arranged on
a supporting disc 28 of a stator disc assembly which is fixed to
housing. Alternatively, an annular refiner plate may be used
instead of an annular array of plate segments. Further, the refiner
plates or plate segments may be arranged in a disc generally
conforming to a plane for a disc refiner or as a frustoconical
plate or a frustoconical assembly of plate segment for a conical
refiner.
[0024] The flinger plate 22 rotates with the rotor disc assembly
16. The flinger plate accepts feed material from a cellulosic
material feeding screw (not show). Feed material flows from the
material feed screw, through at center inlet 30 to the refiner
along a flow direction (F) parallel to an axis 32 of rotation of
the rotor disc 16. The flinger plate 22 assists in turning the flow
of the cellulosic material from an axial direction 32 to a radial
direction that leads a gap 34 between the rotor disc assembly and
the stator disc assembly. If the refiner disc is conical, the
flinger plate assists in turning the flow to a conical path that
leads to a conical gap between conical refiner plates.
[0025] As the feed material moves through the gap 34, the material
is refined by bars and grooves on the opposing plate segments 24,
26 of the rotor and stator plate assemblies. The action of the bars
and grooves separates the feed material into fibers and thus into
pulp. The pulp flows out of the outer periphery of the gap 34 and
into the chamber 14 of the housing 12.
[0026] FIG. 2 is a front view of a flinger plate 100 for a
mechanical refiner comprising feeder bars and deep notches 118, 124
disposed within the feeder bars. The deep notches may be oriented
to reduce the likelihood that fiber will travel into and across the
notch. FIG. 3 is a side view of a cross section of the flinger
plate 100.
[0027] The flinger plate 100 includes a substrate 102 having a
front face 104 and a back face 105 on an opposite side of the
substrate. The flinger plate 100 has a center axis (C) and a center
hub 106 centered on the axis. The center hub may protrude from the
front face 104 of the substrate and has a planar (flat) face.
Alternatively, the center hub 106 may be planar with the front face
104 of the substrate or recessed with respect to the front face of
the substrate.
[0028] An outer annular periphery 108 of the flinger plate 100
defines the outer edge of the substrate 102. The flinger plate 100
may be a single circular disc or an assembly of pie-shaped plate
segments that together form a circular disc.
[0029] Feeder bars 110 protrude from the front face 104 and extend
from the center hub 105 to the outer periphery 107. The feeder bars
110 are swept back from a radial line in a rotational direction R.
The back sweep of the feeder bars 110 aids in flinging feed
material radially outward. The flinger plate 100 and rotor disc
assembly rotate in direction R. The bars can also be straight,
either angled in a feeding angle, or arranged in a substantially
radial direction. The flinger plate 100 is secured to the rotor
disc 16 by fasteners (not shown) that extend through fastener holes
120 in the substrate 102.
[0030] The feeder bars 110 each have a leading side 112, a trailing
side 114 and a wide ridge 116 spanning between top edges of the
leading and trailing sides. Notches 118 extend through feeder bars
110 to form grooves extending from the ridge 116 down towards and
possibly to the substrate 104. Each feeder bar may have one, two,
three or more notches 118 and/or holes 119. The inlet 122 to each
of the notches or holes is on the leading side 112 of the feeder
bar 110 and the outlet 124 is on the trailing side 114 of the
feeder bar. A radially inward notch 118 or hole 119 on each feeder
bar may have an outlet 124 adjacent the center hub 106.
[0031] The notches or grooves may be grouped along the first half
or two-thirds of the radial length of a feeder bar. The depth of
the notches may be from the ridge 116 down half way of the bar to
the substrate, two-thirds to the substrate or all the way to the
substrate 104. The notch may extend into the substrate. Similarly,
the holes 119 may extend into the substrate.
[0032] The notches or holes may be arranged such the inlet 122 is
at a shorter radial distance from the center (C) than the outlet
124. The notches or holes may also be perpendicular to the bars, or
have a reversed direction wherein the inlet is at a greater radial
distance than the outlet.
[0033] The cross-sectional area of the inlet 122 to a notch 118 or
hole 119 may be smaller than the cross-sectional area of the outlet
124. Similarly, the cross sectional area of a notch or hole may
gradually, e.g., linearly, increase in area from the inlet 122 to
the outlet 124.
[0034] The notches 118 and holes 119 allow fluid, such as steam,
under pressure at a leading side 112 of the feeder bar to pass
through the bar to the trailing side 114. The pressure at the
leading side 112 of a feeder bar 110 tends to be greater than the
pressure at the trailing side 114 due to the movement of the
leading side into the feed material and the movement of the
trailing side away from the feed material.
[0035] The greater pressure at the inlets 122 of the notches or
holes will cause fluids, such as steam, to move through the notches
and to the trailing side 114 of the feeder bars. As the fluid exits
the notches, the relatively higher pressure of the fluid increases
the pressure at the trailing side 114 of the feeder bars. This
increased pressure at the trailing sides 114 reduces the tendency
of stagnate flow forming in relatively low regions adjacent the
trailing sides 114 of the feeder bar.
[0036] The notches 118 or holes 119 may be shaped to suppress
fibers being drawn into the inlets 122 of the notches. The shape of
the inlets 122 may include an obtuse angle, a curvature along the
length of the notches or a hole, and an acute angle 128 at the
outlet 124. The obtuse angle 126 may be in a range of 100 degrees
to 160 degrees, 115 to 145 degrees, or some other degree. The
obtuse angle may be measured at the radially inward edge 130 of the
inlet 122. The obtuse angle causes flow moving in front of the
leading side 112 of the feeder bar 110 to turn greater than 90
degrees to enter the inlet 122. The flow that makes this turn
should be primarily liquids and not the fibers in the flow. The
obtuse angle 126 at the inlet 122 also results in a blunt edge at
the radially outward side of the inlet. The blunt edge reduces the
risk that fibers impacting the edge are cut or otherwise
damaged.
[0037] At the outlet 124, the acute angle 128 may be measured at
the radially inward 132 edge of the outlet 124. The acute angle 128
may be in a range of 90 to 30 degrees, 75 to 45 degrees or in
another range of degrees. The curvature along the length of the
notches 118 or hole 119 provides a smooth transition between the
angles of the inlet and outlet to the notch. The angles of the
channels are may be selected to prevent preventing feed material
moving across bars and thus create a loss in the feeding
performance. On the other hand, notches or holes that run
perpendicular to the bars, or even in a direction towards the outer
periphery of the flinger plate may be desirable in certain
cases.
[0038] The sidewalls of the notches 118 or holes 119 may be planer
and perpendicular to the substrate 102 or angled such that the
notch opens from the substrate to the ridge 116. The sidewalls may
also be curved, such as concave or convex, from the substrate to
the ridge.
[0039] The holes may be 119 similar to the notches 118, except that
the ridge extends over the holes but not over notches. The holes
may be individual holes 119 through a feeder bar, two or more holes
that join at their inlet or outlets, and the holes may be tapered
such that their cross-sectional area increases from inlet to
outlet. The holes function similarly to the notches to provide
pressure equalization across the leading and trailing sides of a
bar in a flinger plate.
[0040] The notches 118 or holes 119 may each have a cross sectional
area of at least 9 mm.sup.2 and may have a width less than the
width of the feeder bar with the notch (or holes). The width of the
notch or hole is from one side of the notch or hole to an opposite
side. The width may be constant along the length of the notch or
hole, except at the inlet and outlets may expand. The notches or
holes may also have a variable width, such as being narrow on the
leading edge of the bars, and extending towards the trailing edge
of the bars. This prevents large particles of the feed material to
enter the notches or holes, but also reduces the risk of blocking
the inlets s with material.
[0041] The flinger plate 100 may be formed by casting metal into a
mold form of sand. An imprint of the flinger plate is formed in
sand molds which are clamped together to form a cavity that is
substantially the same shape as the flinger plate. Metal is poured
in the cavity of the sand mold to form the flinger plate. The
flinger plate can also be cast without the notches, and notches can
be made through machining of the bars with suitable tools. The
flinger plate can also be a manufactured plate made of individually
welded components. Holes can be drilled, cast using cores in the
pattern, or made with 3D printed sand molds. Holes can also be made
in bars prior to making a welded assembly.
[0042] FIG. 4 is a front view of a refiner plate segment 200, and
FIG. 5 is side view of a portion of a cross section of the refiner
plate segment 200. The refiner plate segment 200 may be
conventional except for the holes in the bars described below.
[0043] The refiner plate segment 200 is pie-shaped and is assembled
with other refiner plate segments on a rotor or stator disc. The
refiner plate segments are attached to the disc by fasteners
inserted in fastener holes 202. The refiner plate segments are
arranged side 204 to side to form an annular assembly of segments
on the disc. The outer edge 206 of the refiner plate segment 200
forms a circular perimeter when the plate segments are arranged in
the annular assembly. The outer edge 206 of the refining surface of
the refiner plate segment. The inner edge 208 of the refiner plate
segment 200 may be located on the rotor or stator disc adjacent an
outer edge of the flinger plate. The inner edges 208 of the
assembly of refiner plate segments 200 form a circle that surrounds
the outer edge of the flinger plate.
[0044] The front face of the refiner plate segment 200 is a
refining surface. The front face includes a substrate 210 that
extends between the inner and outer edges 206, 208, and between the
sides 204 of the refiner plate segment. The substrate may be planar
from a disc refiner, or the substrate may be arched for a conical
refiner.
[0045] Extending outward from the substrate 210 are bars 212, 214
and 216 arranged in groups. The radially inward most group of bars
212 are thick and spaced relatively far apart. The next group of
bars 214 are narrower and relatively close together, and radially
outermost bars 216 are the narrowest and most closely spaced
together. The bars in each group may be substantially parallel.
Between adjacent bars are grooves that extend down to the substrate
210 and up to the top (ridge) of the bars. The bars and grooves in
each group define a refining sections of the refiner plate segment.
The arrangements of groups of bars and grooves shown in FIG. 4 is
exemplary. Other refiner plates may have a single group of bars and
grooves, two or more groups or bars and grooves that vary in shape
and dimensions in a radial direction of the refiner plate.
[0046] The feed material flows radially outward through a gap 34
(FIG. 1) between the front faces of opposing refiner plates or
assembly of plate segments. The opposing refiner plates or assembly
of plate segments may be a refiner plate assembly and a stator
plate assembly. Some refiners may have two oppositely rotating
discs on either side of the gap. The bars and grooves of one plate
assembly face the bars and grooves on the opposing plate assembly.
The bars and grooves refine the lignocellulosic matter in the feed
material by applying pressure pulses and by shearing the
matter.
[0047] The grooves 217 between bars 212 in the inner refining zone,
the grooves 218 between bars 214 in the middle refining zone and
the grooves 220 between bars 216 is the outer refining zone provide
passages for steam and liquids to flow radially outward. While
fibers also may flow through the grooves, the fibers are refined by
flowing over the bars and in the gap between the refiner
plates.
[0048] To move the fibers out of the grooves and to slow the flow
through the grooves, dams 222, 224, 226, 228 fully or partially
block the grooves. Specifically, partial-height dams 222 and full
height dams 224 are placed are at various locations in the grooves
between the bars 214. Similarly, partial height dams 228 and full
height dams 226 are at various locations between the bars 216.
[0049] As shown in FIG. 5, partial-height dams 222, 228 extend from
the substrate 210 towards the ridge 230 of the bars, but do not
reach the bars. Full height dams 224, 226 extend from the substrate
to the ridge of the bars. The dams divert material flowing through
the grooves towards the gap between the opposing refiner plate
assemblies. The dams also slow the flow of material through the
grooves.
[0050] The dams create stagnate flow zones 232 in the grooves
immediately downstream (radially outward) of the dams. Stagnate
flow zones collect fibers and other particles due to the low
pressures in the zones. These fibers and particles can adhere to
the back of the dams and the sides of the bars near the dams. The
accumulations of fibers, pitch and other particles tend to become
hard and blacken due the high temperatures in the refiner. The
accumulations may periodically break off into small black particles
that can contaminate and discolor the pulp (separated fibers) being
produced by the refiner. The accumulations also may fill the
grooves and thereby reduce the ability of the refiner plates to
refine material and reduce the feed material capacity of the
refiner. Thus, the accumulations may require replacement of the
refiner plate segments.
[0051] To reduce the accumulations behind dams, open passages 234
are formed in the bars and are each positioned radially outward of
a dam. The open passages 234 allow fluid to flow from a high
pressure in a region of one groove away from a dam through a bar
and into a stagnate zone to increase the pressure in that zone. The
increased pressure reduces the tendency for accumulations to form
and thereby reduces the risk that particles of accumulations will
break off and contaminate the pulp. There may be an open passage
234 associated with each dam such that the outlet of the passage
234 is immediately downstream (radially outward and adjacent the
trailing side) of the dam and the inlet opens to a portion of a
groove that does not have a dam. The downstream direction of the
feed material is shown by arrow 236 in FIG. 5.
[0052] The open passages 234 are below the ridge 230 of the bar.
The ridge of the bar applies shear and pressure pulses to the feed
material. A continuously ridge over the open passages 234 allows
the ridge to continue applying shear and pressure forces. Adding a
notch to the ridge to provide a passage through the bar would
interrupt the ridge and reduce the ability of the bar to refine the
feed material.
[0053] The open passage 234 may extend down to the substrate 210 as
shown in FIG. 5 or may in a mid-section of a bar and not reach the
substrate. The open passage may extend towards the ridge of the bar
but should not interrupt the ridge. There may be a substantial
portion of the groove, such as a quarter of the grooves height,
between the ridge and the open passage. Leaving a substantial
portion between the ridge and open passage will allow the ridge to
erode without eroding into the open passage. The open passage may
also be partially or fully below (inside) the substrate.
[0054] The open passage 234 may have a cross section that is
square, rectangular, circular, oval, or any shape that allows steam
or other fluids/material to flow from one groove into the next
groove. The cross sectional area of the open passage may be 9
mm.sup.2 or at least grater than 7 to 8 mm.sup.2. For example, an
open passage 234 may have a square cross of 3 mm.times.3 mm. The
open passages 234 should not be too small, such as below 7 mm.sup.2
to avoid plugging of the passage with material. Similarly, the open
passages 234 should not be so large as to weaken the ridge or the
bar. Open passages 234 having a dimension of 3 mm to 5 mm in a
direction from the substrate to the ridge may be advantageous in
provide a large opening and not weakening the ridge.
[0055] Moreover, the passages 234 may extend into the substrate
such that a portion of the passage extends through the bar and a
parallel portion is embedded in the substrate, as shown in FIG. 5.
Alternatively, the passages 234 may be entirely embedded in the
substrate such that the passage extends below a bar and have the
inlet and outlet at the bottom of the grooves on opposite sides of
the bar.
[0056] The open passages 234 may be perpendicular to the
longitudinal axis of the bar, or may be acute to the longitudinal
axis. Moreover, the cross sectional area of the open passage may be
constant along its length, or may be tapered from the inlet to the
outlet (or vice versa) to achieve a desired flow of steam and other
fluids through the passage.
[0057] The refiner plate segment 200 may be formed by casting metal
into a mold form of sand. An imprint of the refiner plate segment
is formed in sand molds which are clamped together to form a cavity
that is substantially the same shape as the flinger plate. Metal is
poured in the cavity of the sand mold to form the flinger plate.
The open passages may be formed in the sand molds by
three-dimensional printing all or a portion of the sand imprint for
the refiner plate segment. Additionally, the open passages may be
made after the production of castings using drilling and machining
processes, or standard sand castings can have sand cores added to
create the open passages directly in the casting.
[0058] Except as otherwise expressly stated herein, the following
rules of interpretation apply to this specification: (a) all words
used herein shall be construed to be of such gender or number
(singular or plural) as to circumstances require; (b) the singular
terms "a," "an," and "the," as used in the specification and the
appended claims include plural references unless the context
clearly dictates otherwise; (c) the antecedent term "about" applied
to a recited range or value denotes an approximation within the
deviation in the range or values known or expected in the art from
the measurements; (d) the words "herein," "hereby," "hereto,"
"hereinbefore," and "hereinafter," and words of similar import,
refer to this specification in its entirety and not to any
particular paragraph, claim, or other subdivision, unless otherwise
specified; (e) descriptive headings are for convenience only and
shall not control or affect the meaning or construction of any part
of the specification; and (f) "or" and "any" are not exclusive and
"include" and "including" are not limiting. Further, the terms,
"comprising," "having," "including," and "containing" are to be
construed as open-ended terms (i.e., meaning "including but not
limited to").
[0059] Recitation of ranges of values herein are merely intended to
serve as a shorthand method of referring individually to each
separate value falling within the range of within any sub ranges
there between, unless otherwise clearly indicated herein. Each
separate value within a recited range is incorporated into the
specification or claims as if each separate value were individually
recited herein. Where a specific range of values is provided, it is
understood that each intervening value, to the tenth or less of the
unit of the lower limit between the upper and lower limit of that
range and any other stated or intervening value in that stated
range or sub range hereof, is included herein unless the context
clearly dictates otherwise. All subranges are also included. The
upper and lower limits of these smaller ranges are also included
therein, subject to any specifically and expressly excluded limit
in the stated range.
* * * * *