Supported dental plates for a disperser

Description

BACKGROUND OF THE INVENTION1. TECHNICAL FIELD

[0001] This disclosure relates to disperser machines for processing recovered pulp fibers from recycled paper and packaging material, and other material separation machines with opposing discs and intermeshing teeth.2. RELATED ART

[0002] A disperser is a machine used for recycling paper and packaging material. Operators first pulp recycled paper and packaging material to separate the fibers in the material. The operators then feed the pulped fibers through the disperser typically at a high consistency, such as between 20-40% dry contents. Dispersers remove ink, toner, and other "stickies" from the fibers in paper and packaging material. Dispersers also reduce the particulate size of ink, toner and stickies, so that they are not so clearly visible in the final product pulp.

[0003] Each disc typically includes an assembly of annular sector-shaped plate segments arranged in a circular array and mounted on a support disc. The assembly of plate segments is referred to as a plate. The front surface of each plate segment, which faces the front surface of the opposing plate segments, typically includes teeth, also referred to as pyramids, arranged in rows across the plate segment. The rows of teeth typically form an arc across the plate segment. The arced rows of teeth on one plate intermesh with the rows of teeth on an opposing plate. That is, arced rows of teeth on one plate segment rotate freely between arced rows of teeth disposed on the opposite plate segment. Examples of discs for dispersers are shown in U.S. Pat. Nos. 9,145,641; 7,766,269; 7,478,773; 7,472,855; 7,300,008 and 7,172,148; U.S. Pat. App. Pub. Nos. 2014 / 017.4688, and European Patent Application 2,683,870 B1.

[0004] Recycled paper and packaging materials typically include many contaminants, including abrasive particles such as large and hard particles. These abrasive particles wear the disperser teeth, which in turn limits the useful life of the plates.

[0005] To address the problem of contaminants, it is known to form plates for the discs of a disperser from hard-wear alloys which are resistant to wear from abrasive particles. However, hard-wear alloys are brittle. Because of the brittleness, the teeth on the plates may break when impacted by larger hard particles, which contaminate the pulped material. Broken teeth limit the life of the plates and can cause other damage further down the process line.

[0006] To address the brittleness, wide and short teeth have been used on plate segments formed of hard-wearing alloys. In contrast, plate segments with tall teeth are usually made in softer and breakage-resistant alloys that limit the useful lifetime of the plates. Wide and short teeth are more resistant to breakage, but are not suited for higher energy input applications because the wide and short teeth form fewer rows with fewer teeth compared to rows with narrow teeth and thus have fewer intermeshing teeth edges on each row. The shorter teeth reduce the lengths of crossing edges of opposing teeth, which likewise reduces the action on the pulped fibers. Also, the short, wide teeth reduce the gap between the opposing discs and thereby reduces throughput capacity of material flowing through the disperser.

[0007] Also, dams and ramps on the substrate of the front face of the discs and between adjacent teeth have been used to support the teeth to reduce breakages of the teeth. Dams and ramps to address difficulties with brittle teeth formed of hard wearing alloy tend to be relatively large. Large dams and ramps can affect the homogeneity of the fiber material moving between the opposing discs in an undesired manner. Large ramps and especially large dams will also reduce the throughput capacity of disperser plates.

[0008] To give an example, WO 2017 / 001359 A1 relates to an apparatus for the mechanical treatment of high-consistency fiber stock with opposing plates having teeth arranged in two or more annular rows concentric with respect to their center, between which teeth tooth gaps are located through which the fiber stock radially flows. At least part of the tooth gaps has raised portions that extend above the tooth base running between the rows of teeth. The respective maximum height of the raised portions above the tooth base increases radially outwards.

[0009] Also in the disperser known from DE 10 2011 005 273 A1, at least some of the spaces between the teeth are provided with protrusions that extend from the base of the tooth. DE 20 2014 010 374 U1 discloses another similar disperser.SUMMARY OF THE INVENTION

[0010] There is a need for a new plate segment design that allows for rows of tall, narrow teeth to be formed of hard-wearing alloys and which are resistant to tooth breakage. To address this need, the present invention provides plate segments as recited in claims 1 and 2. Optional features are set forth in the respective dependent claims.

[0011] A plate segment is disclosed herein that comprises at least one buttress extending from a face of a tooth to the substrate.

[0012] Without being bound by theory, it is contemplated that the exemplary buttresses disclosed herein, may permit manufactures to include a greater number of taller teeth on the disperser plate segment, thereby increasing the work that the disperser plate segments can impart to the recycled fiber per unit of area.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] 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. FIG. 1A is a front view of a conventional plate segment in a disc in a disperser. FIG. 1B is a side view of a cross section of the plate segment shown in Fig. 1A. FIG. 1C is a side view of a cross section of a portion of a disperser in which is mounted a rotor disc and stator disc. FIGS. 2(A) and 2(B) are side and front views of a portion of a plate segment showing teeth with conventional high ramps. FIGS. 3(A) and 3(B) are side and front views of a portion of a plate segment showing teeth with conventional dams. FIGS. 4(A) and 4(B) are side and front views, respectively, of a portion of a plate segment having teeth with connecting bridges that are not recited in the claims. FIGS. 5(A) and 5(B) are side and front views, respectively, of a portion of another plate segment having teeth with connecting bridges that are not recited in the claims. FIGS. 6(A) and 6(B) are side and front views, respectively, of another plate segment with teeth with connecting bridges that are not recited in the claims. FIGS. 7(A), 7(B), 7(C) and 7(D) are side views of teeth on plate segments showing bridges, which are not recited in the claims, having different cross sectional shapes. FIGS. 8(A) and 8(B) are side and front views of teeth on a plate segments showing pairs of bridges, which are not recited in the claims, between adjacent teeth. FIG. 9 is a perspective view of two adjacent exemplary disperser teeth having a buttress extending from a first tooth side of each of the depicted disperser teeth. FIGS. 10(A) and 10(B) show a perspective view of an exemplary disperser tooth showing a pyramidal-shaped buttress. FIGS. 11(A), 11(B), 11(C), and 11(D) are perspective views of an exemplary disperser tooth showing different shapes of buttresses wherein the abutting area of the buttress is less than the total area of the tooth face to which the buttress abuts. FIGS. 12(A), 12(B), 12(C), 12(D), 12(E), 12(F), 12(G) are side views of exemplary disperser teeth showing exemplary buttresses extending from one or more faces of an exemplary disperser tooth. FIGS. 13(A), 13(B), 13(C), and 13(D) are side views perpendicular to the views of FIG. 12. These figures show the abutting area of the buttress relative to the total area of the first tooth face. DETAILED DESCRIPTION OF THE INVENTION

[0014] The following detailed description of the preferred embodiments is presented only for illustrative and descriptive purposes and is not intended to be exhaustive or to limit the scope of the invention as defined by the claims. The embodiments were selected and described to best explain the principles of the invention and its practical application. One of ordinary skill in the art will recognize that many variations can be made to the invention disclosed in this specification without departing from the scope of the invention.

[0015] Similar reference characters indicate corresponding parts throughout the several views unless otherwise stated. Although the drawings represent embodiments of various features and components according to the present disclosure, the drawings are not necessarily to scale and certain features may be exaggerated in order to better illustrate embodiments of the present disclosure, and such exemplifications are not to be construed as limiting the scope of the present disclosure.

[0016] 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").

[0017] References in the specification to "one embodiment," "an embodiment," "an exemplary embodiment," etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0018] To the extent necessary to provide descriptive support, the subject matter and / or text of the appended claims is incorporated herein by reference in their entirety.

[0019] 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.

[0020] It should be noted that some of the terms used herein are relative terms. For example, the terms "upper" and "lower" are relative to each other in location, i.e. an upper component is located at a higher elevation than a lower component in a given orientation, but these terms can change if the device is flipped. The terms "inlet" and "outlet" are relative to a fluid flowing through them with respect to a given structure, e.g. a fluid flows through the inlet into the structure and flows through the outlet out of the structure. The terms "upstream" and "downstream" are relative to the direction in which a fluid flows through various components, i.e. the flow of fluids through an upstream component prior to flowing through the downstream component.

[0021] The terms "horizontal" and "vertical" are used to indicate direction relative to an absolute reference, i.e. ground level. However, these terms should not be construed to require structure to be absolutely parallel or absolutely perpendicular to each other. For example, a first vertical structure and a second vertical structure are not necessarily parallel to each other. The terms "top" and "bottom" or "base" are used to refer to locations / surfaces where the top is always higher than the bottom / base relative to an absolute reference, i.e. the surface of the Earth. The terms "upwards" and "downwards" are also relative to an absolute reference; an upwards flow is always against the gravity of the Earth.

[0022] Dispersers typically come in one of three varieties: disc, conical, and cylindrical. Although this detailed description primarily describes disc dispersers, conical and cylindrical dispersers typically function in a similar way. Instead of opposing discs, they feature nesting truncated cones and nested cylinders respectively. The exemplary plate segments described herein may be manufactured to work with conical or cylindrical dispersers, and such plate segments and types of dispersers are considered to be within the scope of this disclosure. FIGS. 1A, 1B and 1C show a disperser 10 ( FIG. 1C) which houses rotor plate segments 12 mounted in an annular array to a rotor support disc 14. The rotor plate segments 12 and support disc 14 are rotated about a center axis 16 of the disperser. The rotor plate segments 12 and disc 14 are turned by a shaft 15 drive by a drive motor (not shown). The disperser also houses stator plate segments 18 mounted in an annular array to a stator support disc 20, which is fixed to the housing of the disperser.

[0023] A center inlet 22 to the stator support disc 20 receives material to be processed between the rotor and stator plate segments. The material may be pulp recovered by recycling paper or packaging material. The material moves into a gap 24 between the front faces of the rotor plate segments 12 and the front faces of the stator plate segments 18. The rotation of the rotor plate segments (and stator plate segments if they are configured to turn) creates centrifugal forces that propel the material through the gap 24. As the material moves through the gap 24, the material flows between and over teeth 26 arranged in rows on the front faces of each of the rotor plate segments 12 and the stator plate segments 18.

[0024] The rows of teeth 26 on the rotor plate segments 12 intermesh with the rows of teeth on the stator plate segments 18. To provide for intermeshing, the rows of teeth on the rotor plate segments 12 are at different radii from the center axis 16 than are the rows of teeth on the stator plate segments 18. The rows of teeth each extend through a plane 28 extending through the center axis 16 and radially outward through the gap 24.

[0025] As the material passes through the gap 24, the teeth on the rotor and stator plate segments 12, 18 impact the material and dislodges from the pulp fibers particles of ink, toner and stickies from the fibers of the pulp. Dislodging these particles from the fibers is desired. As the material exits the gap in a radial direction, the material enters an annular chamber 30 of the housing of the disperser 10. The material moves through the chamber to a discharge outlet. After discharge, the material if further processed to separate the dislodged particles from the pulp fibers.

[0026] Plate segments 12, 18 may be, for example, individual annular sector-shaped components or a region of an annular plate. Plate segments that are individual annular sector - shaped components are arranged in an annular array to form a full plate. The plate segments / plate are mounted on a support disc 14, 20. An annular array of rotor plate segments 14 are mounted to the rotor disc support 12, and annular array of stator plate segment 18 are mounted to the stator support disc 13. The plate segments may be fastened to the disc by any convenient or conventional manner, such as by bolts (not shown) passing through bores 17. The plate segments 12, 18 are arranged side-by-side to form the annular array as they are mounted to each disc support.

[0027] The rotor or stator plate may or may not be formed of separate component plate segments. Rather, the plate segments may be joined as a single-piece plate. While plate segments that are separate components are disclosed here, the invention may be embodied in an annular plate in which the plate segments are integrated into a single piece plate.

[0028] A plate segment 12, 18 has an inner edge 32 towards the center axis 18 of its attached disc support and an outer edge 34 near the periphery of the disc support. Each plate segment 12, 18, has a front face with a substrate 45 and, protruding from the substrate 45, concentric rows 42 of teeth 26. The rotation of the rotor disc support 14 and its plate segments 12 apply a centrifugal force to the refined material, e.g., fibers, that cause the material to move through the gap 24 between the discs in a radially outward direction from the inner edges 32 to the outer edges 34 of the plate segments. The pulped material predominantly move between adjacent teeth 26 in each row on the opposing discs. The pulped material flows radially out from the gap 24 at the outer periphery of the discs and into a casing (annular chamber 30) of the refiner 10.

[0029] The rows 26 of teeth on each disc are each at a common radial distance 44 from the disc center 16. The rows 26 on a disc are concentric. The rows one the opposing discs intermesh across the gap 24 such that the teeth 26 intersect the plane 28 in the gap 24 between the discs.

[0030] Fiber passing from the center inlet 22 of the stator disc, through the gap 24 and to the periphery of the discs receive impacts as the rotor teeth 26 pass close to the stator teeth 28. The clearance between the rotor teeth 28 and the stator teeth 28 may be in a range of 0.5 to 12 millimeters ("mm"). The clearance may be selected such that the fibers are severely and alternately flexed as they pass between the teeth in the rows of the rotor and stator discs. Flexing the fiber breaks the ink and toner particles on the fibers into smaller particles and breaks off the stickie particles on the fibers. The clearance should not be so small as to damage or break the fibers.

[0031] A rotor or stator plate segment 12, 18 is shown in more detail in FIGS. 1A and 1B than in FIG. 1C. The plate segment has an inner edge 32 and an outer edge 34. These edges may be arc-shaped, wherein each arc is centered on the center axis 16 when the plate segments are mounted to a disc and in the disperser 10. A back side 36 of the plate is configured to mount to a front surface of support disc 14, 20.

[0032] The front side 38 includes an outer arc-shaped section 40 on which rows 42 of teeth 28 are arranged. Each row 42 is arc-spaced and is at a constant radius 44 from the center axis 16 of the disperser. The teeth extend out from a substrate 45 of the plate segment. An inner section 46 of the front face may be the planar substrate 45 of the front of the plate segment.

[0033] The side edges 48 of the plate segment 12, 18 may be a straight edge aligned along a radius from the center axis 16. The side edges 48 are configured to be adjacent side edges of other plate segments mounted to the stator or rotor support disc. By arranging plate segments side-by-side on a support disc, the plate segments form an annular disc array on the support disc. Each of the rows 42 of teeth 26 on the plate segment are aligned along a common radius with a row of teeth on the other plate segments mounted to the support disc. Thus, the teeth from all of the plate segments mounted to a support disc are arranged in circular rows. These circular rows of teeth on rotor plate segments mounted to the rotor support disc intermesh with circular rows of teeth on stator plate segments mounted to the stator support disc in the disperser.

[0034] FIGS. 2(A), 2(B), 3(A), and 3(B) shown ramps 50 and dams 51 between adjacent teeth 26 in a row 42 of teeth in conventional plate segments. These conventional dams 50 and ramps 51 are large protrusions extending from the substrate 45 of the front face of the plate segment. Ramps 50 may protrude from the substrate by 2 to 6 mm or more in height. Dams 51 may extend above the substrate from a few millimeters to about three-quarters (¾) of the tooth height. The ramps or dams may alternate with bridges between teeth in a row. For example, there may be a series of two to six bridges between adjacent teeth followed by a ramp or dam between the next one to six teeth. Ramps, dams and bridges may also be combined in any variation in between adjacent teeth, such as a bridge and a ramp in the same area.

[0035] As is known in the art, ramps and dams strengthen the teeth to which they are attached. The height of the ramp or dam is selected to provide a desired level of support to the teeth. Ramps or dams that are relatively low as compared to the tooth height provide less support than do taller ramps or dams. Ramps or dams that are tall as compared to tooth height provide good support of the teeth but adversely affect the flow of pulped material through the teeth and can significantly reduce the production capacity of the disperser. Another adverse effect due to tall ramps or dams may be a reduction in the homogeneity of the pulped material by flowing the material in concentrated areas between the discs.

[0036] FIG. 9 is a perspective view of two adjacent exemplary disperser teeth 26 having a buttress 73 extending from a first tooth face 69 of each of the depicted disperser teeth 26. The area 79 ( FIG. 13(A)- (D))of the buttress 73 that abuts the first tooth face 69 (i.e. the "abutting area") is less than the total area 55 ( FIG. 13(A)- (D))of the first tooth face 69. In certain exemplary embodiments, the exposed area 59 ( FIG. 13(A)- (D))is between about 20% and 80% of the first tooth face's total area 55. It will be understood that the first tooth face's total area 55 is the sum of the buttress area 79 and the first tooth face's exposed area 59.

[0037] The tooth 26 further comprises a second tooth face 53 ( FIG. 12(B)) and a body 65 bounded by the first tooth face 69, the second tooth face 53, a first lateral tooth side 67, and a second lateral tooth side 88 ( FIG 13(A)). Without being bound by theory, Applicant believes that the exemplary buttresses 73 described herein provide additional support to the disperser teeth 26, while still permitting sufficient open area 47 ( FIG. 12(A)- (G))between adjacent disperser teeth 26 to allow recycled material to flow through the open area 47 to maintain sufficient throughput.

[0038] The buttress 73 of FIG. 9 has a buttress height h. In the depicted embodiment, the buttress height h is less than the tooth height H, thereby exposing the first tooth face 69. In this depiction, the first tooth face 69 starts as the trailing face of the tooth 26 when the disperser is rotating. Without being bound by theory, it is believed that a majority of dispersion occurs due to the flexing of the recycled fibers between edges of intermeshing teeth 26 on opposite disperser plates. The exposure of the first face 69 allows operators to reverse the rotation of the disperser plates when the leading face (see the second face 53) becomes worn. In this manner, the disclosed embodiment may allow operators to extend the useful life of the disperser plate segments.

[0039] In certain exemplary embodiments, the buttress 73 is disposed on the second tooth face 53. In still other exemplary embodiments, a buttress can be disposed on both the first tooth face 69 and the second tooth face 53. Manufactures can place and configure the buttresses 73 according to the desired use of the disperser.

[0040] Without being bound by theory, it is further contemplated that the use of buttresses 73 such as the exemplary buttresses 73 disclosed herein, permit manufactures to include a greater number of taller teeth 26 on the substrate 45 of the disperser plate segment, thereby increasing the work that the disperser plate segments can impart to the recycled fiber per unit of area. In certain exemplary embodiments, the disperser teeth 26 comprise a flat top 75. In other exemplary embodiments, the top may be pointed.

[0041] The buttress 73 further comprises a distal bottom edge 85, a top edge 83, and a hypotenuse hyp extending form the top edge 83 to the distal bottom edge 85. In certain exemplary embodiments, the widest width w2 of the base B of the buttress 73 is wider than the width w1 at the top edge 83 of the buttress 73.

[0042] FIGS. 10-13 illustrate that the buttress 73 may have any number of shapes provided that the abutting area 79 of the buttress 73 is less than the total area 55 of the tooth face 69, 53 to which the buttress 73 abuts. Such shapes include by way of example only, a shape selected from the group consisting of: a tetrahedral prism, a pyramid, a triangular prism, a quadrilateral prism, and a trapezoidal prism. Such shapes may be symmetric or asymmetric.

[0043] FIG. 12 is a cross sectional view of a row along the length of a row of teeth. In FIG. 12, each buttress 73 is a different exemplary embodiment of an exemplary buttress. FIG. 12(A) depicts the distal bottom edge 85 not extending to the second tooth face 53 of the adjacent tooth 26. FIG. 12(D) shows the distal bottom edge 85 extending up the second tooth face 53 of the adjacent tooth 26. FIG. 12(E) depicts a first buttress 73 extending from the first face of a first disperser tooth 26 and a second buttress 73 extending from the second face 53 of an adjacent disperser tooth 26.

[0044] FIG. 13 is a cross sectional side view that intersects the junction of an exemplary buttress 73 and the first tooth face 69 to show a cross section of the buttress 73. FIG. 13 better illustrates the abutting area 79 relative to the exposed area 59 of the first tooth face 69. As FIGS. 13(A)- (D)demonstrate, the shape of the buttress 73 may vary greatly provided that the abutting area 79 is less than the total area 55 of the tooth face 69, 52 to which the buttress 73 abuts.

[0045] An exemplary plate segment comprises: a substrate having a front side and a back side, wherein the back side is configured to be mounted to a support disc of the disperser, rows of teeth protruding from the front side of the substrate, wherein the rows are arranged along an arc extending from a first lateral side of the plate segment to an opposite lateral side of the plate segment, wherein a tooth in the rows of teeth has a first face distally disposed from a second face along a tooth body having a first tooth lateral side and a second tooth lateral side and, wherein a buttress extends from the first face of the tooth to the substrate adjacent to the first face of the tooth.

[0046] An exemplary plate segment further comprises a buttress extending from the second face of the tooth to the substrate adjacent the second face of the tooth.

[0047] In an exemplary embodiment, the buttress has a height and wherein the height of the buttress is less than the height of the tooth from which the buttress extends.

[0048] In an exemplary embodiment, the buttress further comprises an abutting area, wherein the first tooth face further comprises a total area, and wherein the abutting area of the buttress is less than the total area of the first tooth face.

[0049] In an exemplary embodiment, a difference between the abutting area and the total area defines an exposed area.

[0050] In an exemplary embodiment, the exposed area is in a range of 20% to 80% of the total area of the first tooth face.

[0051] In an exemplary embodiment, the buttress has a shape selected from the group consisting of: a tetrahedral prism, a pyramid, a triangular prism, a quadrilateral prism, and a trapezoidal prism.

[0052] In an exemplary embodiment, the tooth further comprises a flat surface disposed at the top of the tooth among the first tooth face, the second tooth face, the first lateral tooth side, and the second lateral tooth side.

[0053] In an exemplary embodiment, the buttress further comprises a base disposed on the substrate adjacent to the first face of the tooth, wherein the base has a width, and where the base width is wider than a width at a top edge of the buttress.

[0054] In an exemplary embodiment, the buttress further comprises a hypotenuse extending from a top edge of the buttress to a distal bottom edge of the buttress.

[0055] In an exemplary embodiment, the distal bottom edge adjoins a second tooth face of an adjacent tooth.

[0056] While the invention has been described in connection with what is presently considered the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the scope of the invention.

Claims

1. A plate segment comprising: a substrate (45) having a front side (38) and a back side (36), wherein the back side (36) is configured to be mounted to a support disc (14, 20) of a disperser (10); and rows (42) of teeth (26) protruding from the front side (38) of the substrate (45), wherein the rows (42) are arranged along an arc extending from a first lateral side of the plate segment to an opposite lateral side of the plate segment, wherein a tooth (26) in the rows of teeth (26) has a first face (69) distally disposed from a second face (53) along a tooth body having a first tooth lateral side (67) and a second tooth lateral side (88), and wherein the plate segment further comprises at least one buttress (73) which extends from the first face (69) of the tooth (26) to the substrate (45) adjacent to the first face (69) of the tooth or from the second face (53) of the tooth (26) to the substrate (45) adjacent the second face (53) of the tooth (26), characterized in that the buttress (73) further comprises a hypotenuse (hyp) extending from a top edge (83) of the buttress (73) to a distal bottom edge (85) of the buttress (73).

2. A plate segment comprising: a substrate (45) having a front side (38) and a back side (36), wherein the back side (36) is configured to be mounted to a support disc (14, 20) of a disperser (10); and rows (42) of teeth (26) protruding from the front side (38) of the substrate (45), wherein the rows (42) are arranged along an arc extending from a first lateral side of the plate segment to an opposite lateral side of the plate segment, wherein a tooth (26) in the rows of teeth (26) has a first face (69) distally disposed from a second face (53) along a tooth body having a first tooth lateral side (67) and a second tooth lateral side (88), and wherein the plate segment further comprises at least one buttress (73) which extends from the first face (69) of the tooth (26) to the substrate (45) adjacent to the first face (69) of the tooth or from the second face (53) of the tooth (26) to the substrate (45) adjacent the second face (53) of the tooth (26), characterized in that the buttress (73) has a shape selected from the group consisting of a tetrahedral prism, a pyramid, and a triangular prism.

3. The plate segment of claim 2, wherein the buttress (73) further comprises a hypotenuse (hyp) extending from a top edge (83) of the buttress (73) to a distal bottom edge (85) of the buttress (73).

4. The plate segment of claim 1 or 3, wherein the distal bottom edge (85) of the buttress (73) adjoins a second tooth face (53) of an adjacent tooth (26).

5. The plate segment of claim 1 or 2, wherein the buttress (73) has a height (h) and wherein the height (h) of the buttress (73) is less than the height (H) of the tooth (26) from which the buttress (73) extends.

6. The plate segment of claim 1 or 2, wherein the buttress (73) further comprises an abutting area (79), wherein the first tooth face (69) or the second tooth face (53) to which the buttress (73) abuts further comprises a total area (55), and wherein the abutting area (79) of the buttress (73) is less than the total area (55) of the tooth face (69, 53) to which the buttress (73) abuts.

7. The plate segment of claim 6, wherein a difference between the abutting area (79) and the total area (55) defines an exposed area (59).

8. The plate segment of claim 7, wherein the exposed area (59) is in a range of 20% to 80% of the total area (55) of the tooth face (69, 53) to which the buttress (73) abuts.

9. The plate segment of claim 1 or 2, wherein the tooth (26) further comprises a flat surface (75) disposed at the top of the tooth (26) among the first tooth face (69), the second tooth face (53), the first lateral tooth side (67), and the second lateral tooth side (88).

10. The plate segment of claim 1 or 2, wherein the buttress (73) further comprises a base (B) disposed on the substrate (45) adjacent to the first face (69) of the tooth (26), wherein the base (B) has a width (w2), and where the base width (w2) is wider than a width (w1) at a top edge (83) of the buttress (73).

11. The plate segment of any of the preceding claims, comprising a buttress (73) extending from the first face (69) of the tooth (26) to the substrate (45) and a buttress (73) extending from the second face (53) of the tooth (26) to the substrate (45).