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. [0004] 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.

[0005] 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.

[0006] 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 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 1mm to substantially 30mm, a width between substantially 1mm 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 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.

[0012] 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

[0013] 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.

[0015] Fig. 2 depicts a partial perspective view of a wedge wire assembly, according to non-limiting implementations.

[0016] Fig. 3 depicts a partial perspective view showing a cylindrical arrangement of a wedge wire assembly, according to non-limiting implementations.

[0017] 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.

[0018] 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.

[0019] Fig. 6 depicts a side view of a waste compactor showing a partially perforated compression zone structure, according to non-limiting implementations. [0020] Figs. 7 to 9 depict partial perspective views of wedge wire assemblies, according to non-limiting implementations.

[0021] 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. 5,61 1,268 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 ⁰ that can be between approximately to approximately 60°. Further, variations in thickness T, width W and included angle A ⁰ 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 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 Wc 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. [0029] 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.

[0030] 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.

[0031] Attention is now directed to Fig. 4 which depicts cylindrical wedge wire assembly 106 installed between a body 1 18 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 1 10. 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 1 12. Drive unit 1 12 can comprise any suitable drive unit, including but not limited to an electric drive unit, a gas driven drive unit, and/or drive unit 1 12 can be connected to any suitable electric or gas driven motor.

[0032] In implementations depicted in Fig. 4, the length of assembly 106 extends from any suitable point along feedscrew 108 after drive unit 1 12 (including but not limited to a point adjacent drive unit 1 12 or a point approximately midway along feedscrew 108 or any other suitable point) to an end distal from drive unit 1 12, terminating at or before a cutting plate 1 14 that, in operation, shreds material fed through waste compactor 103 by the feedscrew 108. A drain channel 1 16 is provided at any suitable point in a base of a 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 1 10 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 1 16. 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 1 18 are such that the expelled fluids can flow freely to drain channel 1 16.

[0034J 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 1 16.

[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 1 12.

[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 103 a, according to non-limiting implementations. Waste compactor 103 a is similar to waste compactor 103, with like elements having like numbers with however an "a" appended thereto. For example, hopper 1 10a is similar to hopper 1 10. However, waste compactor 103a comprises a second conical wedge wire assembly 120 in a downstream conical compression portion 122 of the compactor body 1 18a. 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 1 18a. 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 1 18a. 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 1 14a), to any suitable point between its upstream end and material egress aperture 130a of an exit passage of waste compactor 103 a. By including the wedge wire assembly in the compression portion 122 of waste compactor 103 a, 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.

[0039] 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 1 10 and a conical compression portion for compressing waste material adjacent material egress aperture 103.

[0040] 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 1 18b 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 1 16b. Fluids expelled via 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 ^b 'd" appended thereto. For example feedscrew 108d is similar to feedscrew 108. However, in these implementations wires lOOd spiral around feedscrew 108d at any suitable helix angle. For example, wires lOOd 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 lOOd can spiral at any suitable helix angle different from the helix angle of feedscrew 108d.

[0043] In other implementations, wires lOOd 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 1 16 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 lOOd spiral with a helix angle similar to feedscrew 108d, flow of waste material is further enhanced. However, wedge wires lOOd that spiral with a helix angle opposite to that of feedscrew 108d are also advantagesous, enhancing the sliredding 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 the above implementations and examples are only illustrations of one or more implementations.