Note: Descriptions are shown in the official language in which they were submitted.
CA 02722846 2010-10-18
Waste Compactor with Liquid Separation
FIELD
[0001] The specification relates generally to waste compactors, and
specifically to a
waste compactor for liquid separation and a wedge wire assembly therefor.
BACKGROUND
[0002] Waste compaction machinery generally includes an infeeding auger and/or
feedscrew to chop and/or compress waste material. The feedscrew is powered to
force
the waste material into a cylindrical and/or conical channel which can be
fitted with a
nozzle that can be variably altered in diameter so as to compress the material
as it is
forced through the channel. A shaft of the feedscrew shaft can have an
extension,
downstream of a conical compression section that helps form the compressed
waste
material into an annular shape to cause the waste material to support and
centralize this
portion of the feedscrew within the channel. In some applications waste
compaction
machinery can be used to compact waste material into pellet or billet forms
that can be
easily handled and used as a fuel in a combustion system.
SUMMARY
[0003] An aspect of the present specification provides a device added to a
waste
compactor which aids the separation of liquids that may be ingested by the
waste
compactor. Some examples are: compaction of plastic containers containing
aqueous
and/or oily liquids; compaction of organic fibrous waste that has a liquid
content;
compaction of absorbent waste material that contains a liquid; and dewatering
of sludge.
In applications where the compacted output of the waste compactor machine is
to be used
as a fuel in a combustion system it is desirable that the output be as dry as
possible.
Alternatively, in applications where the compacted output must meet certain
criteria to
allow it to be handled as a non-hazardous material, it is desirable that the
in-fed liquid
content be separated from the compacted output sufficiently to meet such
criteria.
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ti
[00041 Another aspect of the present specification provides a liquid
separation device
that surrounds at least part of a feedscrew in a waste compactor that enhances
the
separation of liquid content from the solid content of the in-fed material.
Multiple
parallel rods (e.g. wedge wires), each having a trapezoidal cross-section, are
longitudinally arranged to completely or partially, surround the feedscrew
periphery and
aligned to be parallel to the feedscrew's axis of rotation. The size and
spacing of the rods
permit easy passage and drainage of a liquid as it is expelled from the in-fed
material
before and during its compression in the waste compactor. The size and spacing
of the
rods are selected to provide sufficient strength to their structure so as to
resist the internal
forces generated by the compression of the in-fed waste. The body of the waste
compactor is provided with suitable drainage means to collect and channel the
expelled
fluids.
[00051 A further aspect of the present specification provides a waste
compactor with
liquid separation, comprising: a hopper for accepting waste material including
a fluid; a
feedscrew for accepting the waste material from the hopper, for at least one
of chopping
and compress the waste material, and expelling the fluid from the waste
material; a body
enclosing the feedscrew, comprising a material egress aperture and a drainage
aperture,
the waste material conveyed away from the hopper by rotation of the feed screw
towards
the material egress aperture; and a wedge wire assembly between the body and
the
feedscrew, the wedge wire assembly at least partially surrounding the
feedscrew along a
longitudinal axis, the wedge wire assembly comprising: a plurality of wedge
wires
extending longitudinally along the feedscrew and spaced circumferentially
around the
feedscrew thereby forming a plurality of gaps there between such that the
fluid expelled
from the waste material can pass through the gaps and out of the body via the
drainage
aperture.
[00061 The plurality of wedge wires can further form a spiral around the
feedscrew. The
plurality of wedge wires can comprise a helix angle substantially similar to a
helix angle
of the feedscrew thereby aiding flow of the waste material through the
feedscrew. The
plurality of wedge wires can comprise a helix angle substantially opposite to
a helix angle
of the feedscrew thereby resisting flow of the waste material through the
feedscrew and
enhancing a shredding action at a periphery of feed screw fights. The
plurality of wedge
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wires can comprise a helix angle substantially different from a helix angle of
the
feedscrew.
[0007] The feed screw can comprise a cylindrical feed portion for accepting
the waste
material from the hopper and a conical compression portion for compressing the
waste
material adjacent the material egress aperture. The wedge wire assembly can at
least
partially surround at least one of the cylindrical feed portion and the
conical feed portion;
the wedge wire assembly being substantially cylindrical when at least
partially
surrounding the cylindrical feed portion; and the wedge wire assembly being
substantially conical when at least partially surrounding the cylindrical feed
portion.
[0008] The drainage aperture can comprise at least one of a drain channel and
at least one
drain hole. The at least one drain hole can be one of a plurality of drain
holes in a conical
compression portion of the feedscrew adjacent the material egress aperture.
The wedge
wire assembly can at least partially surround the conical compression portion,
the wedge
wire assembly being substantially conical surrounding the cylindrical feed
portion.
[0009] Each of the plurality of wedge wires can be at least one of. a rod;
substantially
trapezoidal in cross-section, a trapezoidal base of each the wedge wires
substantially
adjacent an outer diameter of the feedscrew; substantially triangular in cross-
section;
substantially square in cross-section; substantially rectangular in cross-
section; and at
least partially curved in cross-section. When each of the plurality of wedge
wires is
substantially trapezoidal in cross-section, each of the plurality of wedge
wires can have a
thickness between substantially lmm to substantially 30mm, a width between
substantially lmm and 30mm and an included angle between substantially 1 and
substantially 60 .
[0010] The plurality of gaps can widen radially away from the feedscrew. The
wedge
wire assembly can be at least one of: an integral assembly; and can further
comprise
reinforcing hoops extending radially around the plurality of wedge wires; the
reinforcing
hoops spaced longitudinally between substantially 30mm and more than 500mm.
[0011] Yet a further aspect of the present specification provides a wedge wire
assembly
enabled for placement between a body and a feedscrew of a waste compactor, the
wedge
wire assembly enabled to at least partially surround the feedscrew along a
longitudinal
axis, the wedge wire assembly comprising: a plurality of wedge wires enabled
to extend
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longitudinally along the feedscrew and spaced circumferentially around the
feedscrew
thereby forming a plurality of gaps there between such that fluid expelled
from waste
material being compacted by the feedscrew can pass through the gaps.
[00121 The plurality of wedge wires can further enabled to form a spiral
around the
feedscrew. The plurality of wedge wires can comprise a helix angle
substantially similar
to a helix angle of the feedscrew thereby aiding flow of the waste material
through the
feedscrew. The plurality of wedge wires can comprise a helix angle
substantially
opposite to a helix angle of the feedscrew thereby resisting flow of the waste
material
through the feedscrew and enhancing a shredding action at a periphery of feed
screw
fights. The plurality of wedge wires can comprise a helix angle substantially
different
from a helix angle of the feedscrew.
BRIEF DESCRIPTIONS OF THE DRAWINGS
[00131 For a better understanding of the various embodiments described herein
and to
show more clearly how they may be carried into effect, reference will now be
made, by
way of example only, to the accompanying drawings in which:
[0014] Fig. 1 depicts a section view through a compactor with contracting
nozzle,
according to the prior art.
[00151 Fig. 2 depicts a partial perspective view of a wedge wire assembly,
according to
non-limiting implementations.
[00161 Fig. 3 depicts a partial perspective view showing a cylindrical
arrangement of a
wedge wire assembly, according to non-limiting implementations.
[00171 Fig. 4 depicts a section view of a waste compactor showing an installed
cylindrical arrangement of a wedge wire assembly, according to non-limiting
implementations.
[00181 Fig. 5 depicts a section view of a waste compactor showing installed
cylindrical
and conical arrangements of wedge wire assemblies, according to non-limiting
implementations.
[00191 Fig. 6 depicts a side view of a waste compactor showing a partially
perforated
compression zone structure, according to non-limiting implementations.
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[0020] Figs. 7 to 9 depict partial perspective views of wedge wire assemblies,
according
to non-limiting implementations.
[00211 Fig. 10 depicts a partial perspective view showing a cylindrical
helical
arrangement of a wedge wire assembly, according to non-limiting
implementations.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0022] Fig. 1 depicts a section view of a waste compactor 10 with a
contracting nozzle 12
according to the prior art, for example as found in US Patent No. 5,611,268 to
Hamilton,
filed June 9, 1996. Waste compactor 10 comprises a feedscrew 13 for compacting
waste
materials, which can be further compacted with nozzle 12. A drain for liquids
is also
provided (not shown) which is prone to blockage from waste material.
[0023] Fig. 2 depicts a partial perspective view of wedge wires 100, according
to non-
limiting implementations. Wedge wires 100 will also be interchangeably
referred to as
wires 100. Furthermore, a single one of wedge wires 100 will be
interchangeably
referred to as a wedge wire 100 and/or a wire 100. In depicted
implementations, each
wedge wire 100 comprises a rod of trapezoidal cross section having any
suitable
dimensions. In non-limiting implementations, in cross section, each wire 100
can have a
thickness "T" between approximately 1 mm and approximately 30 mm, a width "W"
between approximately 1 mm and approximately 30 mm. Further, in non-limiting
implementations in cross-section, trapezoidal sides of each wire 100 can form
an
included angle A that can be between approximately 1 to approximately 60 .
Further,
variations in thickness T, width W and included angle A are within the scope
of present
implementations, including variations in wedge wire 100 and variations between
different
wedge wires 100.
[0024] Furthermore, pairs of wedge wires 100 form a gap S there between,
described in
further detail below.
[0025] However, it is appreciated that wires 100 can be of any suitable cross
sectional
shape, including but not limited to triangular, rectangular, square,
pentagonal, and/or at
least partially curved. For example, Fig. 7 depicts wedge wires 100a that are
rectangular
in cross section having a width Wa and a thickness Ta, and are arranged
circumferentially
such that a gap Sa there between widens as radius increases. Similarly, Fig. 8
depicts
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wedge wires 100b that are triangular in cross section having a width Wb and a
thickness
Tb, and are arranged circumferentially such that a gap Sb there between widens
as radius
increases. Further, Fig. 9 depicts wedge wires 100c that are trapezoidal in
cross section
but with curved sides having a width We and a thickness Tc, and are arranged
circumferentially such that a gap Sc there between widens as radius increases.
It is
appreciated that any other suitable wedge wire shape is within the scope of
present
implementations. It is yet further appreciated that variations on the shapes
described
herein are also within the scope of present implementations. For example,
curvature of
the sides of wedge wires 100 (including sides facing feedscrew 108, as
described below)
and/or variations from 90 in squares, rectangles etc., and/or imperfections
and/or
variations in longitudinal and/or circumferential alignment between wedge
wires 100 are
all within the scope of present implementations.
[0026] Each wire 100 can be manufactured from any suitable material, including
but not
limited to steel, stainless steel, 304 stainless steel and the like.
[0027] In any event, as depicted in Figs. 3 and 4, in non-limiting
implementations, wedge
wires 100 are assembled substantially parallel with each other and formed into
a
cylindrical wedge wire assembly 106 (also referred to interchangeably as
assembly 106),
having an internal diameter slightly larger than an outer diameter 102 of
feedscrew 108 of
a waste compactor 103, such that assembly 106 can at least partially surround
the outer
diameter 102 of feedscrew 108 along a longitudinal axis, as will be presently
described.
It is appreciated that wedge wires 100 need not be exactly parallel and
deviations from
parallel are within the scope of present implementations.
[0028] With reference to Fig. 3, wedge wires 100 are assembled with their
trapezoidal
base side, i.e. the longest side W, facing feedscrew 108 and approximately
adjacent an
outer diameter 102 of feedscrew 108. With reference to Fig. 2, wires 100 are
spaced
circumferentially forming a gap "S" between each of them. The size of gap S
can be
between 0 mm and 30mm. Hence, wires 100 in assembly 106 form a plurality of
gaps S
there between. Further, variations in the size of each of the plurality of
gaps S are within
the scope of present implementations, including variations in a single gap S
and
variations between different gaps S.
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[00291 In some implementations, assembly 106 further comprises reinforcing
hoops 104
to which wires 100 are attached at a side opposite the trapezoidal base side.
It is
appreciated that hoops 104 are used to fabricate assembly 106. It is further
appreciated
that hoops 104 can be made from any suitable material, including but not
limited to
materials similar to that of wires 100. Hoops 104 are spaced longitudinally
"L" at any
suitable distance. In particular non-limiting implementations, the
longitudinal spacing L
between hoops 104 can be between 30mm and more than 500mm. It is appreciated
that
spacing L can be dependent on the length of assembly 106, length of feedscrew
108, or
the like. Further, hoops 104 can be welded to wires 100 in any suitable
manner.
[00301 While not depicted, it is further appreciated in some implementations,
wires 100
can be joined integrally with integrated connectors joining wires 100 at
suitable positions
in assembly 106. It is yet further appreciated that hoops 104 can be integral
with wires
100. In yet further implementations wires 100 can be welded together and/or
reinforced
in any suitable manner. Indeed, it is yet further appreciated that the
assembly of wires
100 is generally non-limiting.
[00311 Attention is now directed to Fig. 4 which depicts cylindrical wedge
wire assembly
106 installed between a body 118 of waste compactor 103 and feedscrew 108, in
non-
limiting implementations. Assembly 106 surrounds a portion of the feedscrew
108 that
can have flights of generally constant height and is downstream of a hopper
110. It is
appreciated that feedscrew 108 is arranged to receive waste material
comprising a liquid
from hopper 100, and that feedscrew 108 is driven by a drive unit 112. Drive
unit 112
can comprise any suitable drive unit, including but not limited to an electric
drive unit, a
gas driven drive unit, and/or drive unit 112 can be connected to any suitable
electric or
gas driven motor.
[00321 In implementations depicted in Fig. 4, the length of assembly 106
extends from
any suitable point along feedscrew 108 after drive unit 112 (including but not
limited to a
point adjacent drive unit 112 or a point approximately midway along feedscrew
108 or
any other suitable point) to an end distal from drive unit 112, terminating at
or before a
cutting plate 114 that, in operation, shreds material fed through waste
compactor 103 by
the feedscrew 108. A drain channel 116 is provided at any suitable point in a
base of a
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compactor body 118 to allow fluids separated from the in-fed waste material to
be
collected.
[0033] In operation, in-fed waste material is conveyed away from hopper 110 by
rotation
of feedscrew 108. The waste material is compressed and shredded by waste
compactor
103 and the fluid within the waste material is expelled from the compressed
solids and
passes through gaps S between wires 100 to leave waste compactor 103 via the
drain
channel 116. The size of gap S between the wedge wires 100 and the spacing of
the
wedge wire assembly from the structure of the compactor body 118 are such that
the
expelled fluids can flow freely to drain channel 116.
[0034] In depicted implementations, when wedge wires 100 are trapezoidal in
cross-
section, wedge wires 100 are assembled with their trapezoidal base side, the
longest side
W, innermost, approximately adjacent the outer diameter 102 of feedscrew 108.
This
orientation helps ensure that gaps S between wires 100 remain unclogged, since
each gap
100 widens as it progress radially away from the longitudinal axis of
feedscrew axis 108.
Any debris small enough to enter a gap S is flushed through by the separated
fluids and
exits body 118 via drain channel 116.
[0035] Furthermore, it is appreciated that the longitudinal alignment of wires
100 is
parallel to the centerline of feedscrew 108, which aids passage of solid waste
through
waste compactor 103.
[0036] It is further appreciated that body 118 comprises a material egress
aperture 130 of
an exit passage of waste compactor 103 where the compressed solid waste
material exits
waste compactor 103, the material egress aperture 130 being distal from drive
unit 112.
[0037] In particular non-limiting implementations, assembly 106 comprises
wedge wires
100b comprising a triangular cross-section, as depicted in Fig. 8, having a
width Wb of
approximately 2.2 mm, a thickness Tb of approximately 4.5 mm and a gap Sb of
approximately 1 mm.
[0038] Attention is now directed to Fig. 5, which depicts a section view of a
waste
compactor 103a, according to non-limiting implementations. Waste compactor
103a is
similar to waste compactor 103, with like elements having like numbers with
however an
"a" appended thereto. For example, hopper 110a is similar to hopper 110.
However,
waste compactor 103a comprises a second conical wedge wire assembly 120 in a
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downstream conical compression portion 122 of the compactor body 118a. In
conical
compression portion 122, flights of feedscrew 108a are formed so that their
outer
diameter reduces in height to conform to the conical compression portion 122
of the
compactor body 118a. It is appreciated that assembly 120 is similar to
assembly 106,
however while assembly 106 is generally cylindrical, assembly 120 is generally
conical
in accordance with conical compression portion 120. Further, it is appreciated
that
assembly 120 is installed between an outer surface of the conical portion of
feedscrew
108a and an inner surface of conical compression portion 122 of compactor body
118a.
Wedge wire assembly 120 extends from any suitable point along feedscrew 108a
in
compression portion 122 (including but not limited to an upstream end
terminating at, or
prior to, cutting blade 114a), to any suitable point between its upstream end
and material
egress aperture 130a of an exit passage of waste compactor 103a. By including
the
wedge wire assembly in the compression portion 122 of waste compactor 103a,
continued separation and drainage of fluids can be enhanced as waste material
is
compressed. Fluids being expelled in the compression portion 122 of waste
compactor
103a can also exit compactor body 118a via drain channel 116a.
[00391 It is further appreciated that in implementations depicted in Fig. 4,
feedscrew 108
also comprises a cylindrical feed portion for accepting waste material from
hopper 110
and a conical compression portion for compressing waste material adjacent
material
egress aperture 103.
[00401 Attention is now directed to Fig. 6, which depicts a side view of waste
compactor
103b, according to non-limiting implementations. Waste compactor 103b is
similar to
waste compactor 103, with like elements having like numbers with however an
"a"
appended thereto. For example, aperture 130b is similar to aperture 130. While
not
depicted, it is appreciated that internal to waste compactor 103b is a
feedscrew similar to
feedscrew 108 and/or feedscrew 108a, and at least one assembly similar to
assembly 106
and/or assembly 120. However, in these implementations, compression portion
122b of
compactor body 118b is partially perforated with at least one hole 126 and/or
holes 126
to further aid the separation of fluids during the compression of the
material. For
example, fluids expelled from waste material in compression portion 122b can
be
expelled through hole(s) 126 in addition to, or in place of drain 116b. Fluids
expelled via
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hole(s) 126 can flow into a collection tray 128 positioned beneath waste
compactor 103b.
This implementation can be used in place of the conical wedge wire assembly
120 or in
combination with conical wedge wire assembly 120.
[0041] With reference to Figs. 3 and 4, it is appreciated that in depicted
implementations,
wires 100 extend straight and parallel to along a longitudinal axis feedscrew
108.
[0042] Attention is next directed to Fig. 10, which is substantially similar
to Fig. 3, with
like elements having like numbers with a "d" appended thereto. For example
feedscrew
108d is similar to feedscrew 108. However, in these implementations wires 100d
spiral
around feedscrew 108d at any suitable helix angle. For example, wires 100d can
spiral at
a helix angle similar to a helix angle of feedscrew 108d. Such an arrangement
can aid in
the flow of material through waste compactor 103. In yet further
implementations, the
wires 100d can spiral at any suitable helix angle different from the helix
angle of
feedscrew 108d.
[0043] In other implementations, wires 100d can spiral at a helix angle
opposite the helix
angle of feedscrew 108d which resists the flow of material through waste
compactor 103
and thereby enhances the shredding action of the waste material at the
periphery of the
feedscrew flights.
[0044] Various advantages will now be apparent. Gaps S between wedge wires 100
aid in
collecting fluid expelled from waste material. Further, as wedge wires 100
extend along
the longitudinal axis of feedscrew 108, wedge wires 100 aid in flow of waste
material
through waste compactor 103. Wedge wires 100 also provide clear exit paths for
the
liquid to drain through and prevents blockage of the drainage paths (e.g.
drain 116 and/or
holes 126). Further advantages are also apparent. As the gaps S between wedge
wires
100 widens as it progress radially away from the feedscrew 108 the gaps S
between the
wedge wires remain unclogged. Further, when wedge wires 100d spiral with a
helix
angle similar to feedscrew 108d, flow of waste material is further enhanced.
However,
wedge wires 100d that spiral with a helix angle opposite to that of feedscrew
108d are
also advantagesous, enhancing the shredding action of the waste material at
the periphery
of the feedscrew flights.
[0045] Persons skilled in the art will appreciate that there are yet more
alternative
implementations and modifications possible for implementing the embodiments,
and that
CA 02722846 2010-10-18
the above implementations and examples are only illustrations of one or more
implementations.
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