Rotor with forward-moving blades for pressure screen cylinders.

Abstract

The present disclosure relates to a rotor for a pressure screen cylinder for removing solid contaminants from a solid suspension. The rotor comprises a cylindrical hub, a plurality of metal strips spaced radially outward from the hub, and a plurality of vanes connecting the plurality of metal strips to the hub. The vanes have a leading edge with an advancing shape. The advancing shape creates streamlines that move contaminants and fibers from the normal local flow field and dislodged contaminants and fibers from the inner surface of the pressure screen cylinder radially inward toward the hub. The streamlines created by the advancing vanes can reduce or prevent accumulation of solid contaminants on the leading edge of the vane and the leading edge of the metal strips. The vanes can also have a relief area proximate to the inner end of the vane.

Description

Related Applications

[0001] This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 333,283, entitled "Rotor with Forward-Swept Struts for Pressure Screen Cylinders," filed April 21, 2022, the entire contents of which are incorporated herein by reference. [Technical field]

[0002] The present invention relates generally to screening devices for removing oversized solid contaminants from a solid suspension, and more particularly to a pressure screen having a cylindrical filter housed within a rotor having forward-moving blades. [Background technology]

[0003] In the paper industry, the process for making paper requires the production of pulp, which is a solid suspension of fibers, such as cellulose or other fibers. Depending on the source of the fiber, the pulp may contain various concentrations and sizes of solid contaminants, such as wood chips, fiber bundles, metal pieces, hardened glue, or other contaminants. For example, the increased use of recycled paper as a fiber source may increase the amount of hardened glue, metal pieces, and wood chips in the pulp. These oversized solid contaminants may reduce paper quality and / or block the flow of the pulp in the Fourdrinier headbox or other paper-making processes.

[0004] Before the pulp is introduced into the paper making process, it is often screened to remove oversized solid contaminants from the pulp. Pulp screening may also be used to screen the pulp for fiber length or fiber stiffness. Pulp screening may be achieved by introducing the pulp into a pressure screen, with the acceptable portion of the pulp passing through the holes or slots in the screen. The solid contaminants or unacceptable portions of the pulp (e.g., long or stiff fibers, when sorting based on fiber characteristics) do not pass through the slots or holes in the screen and are discharged from the outlet of the pressure screen device. Pressure screen devices may also be used to remove oversized solid contaminants from suspensions and solid suspensions in other industries outside of the paper and pulp industry.

[0005] Pressure screen devices for screening paper pulp typically include a pressure screen cylinder and a rotor disposed within the pressure screen cylinder. The rotor has a plurality of metal strips that, as the rotor rotates, traverse the metal strips circumferentially around the inner surface of the pressure screen cylinder. The movement of the metal strips along the inner surface of the pressure screen cylinder creates pressure pulses that dislodge contaminants and fibers entangled on the inner surface of the pressure screen cylinder and prevent blockage of the screen with solid contaminants and fibers. Summary of the Invention [Problem to be solved by the invention]

[0006] In a conventional rotor for a pressure screen cylinder, the rotor comprises a hub and a number of metal strips oriented generally parallel to the rotor's axis of rotation. Each metal strip is connected to the hub by a number of struts. The struts of a conventional rotor extend radially outward to the metal strips. The rotor assembly rotates among the suspension fibers and contaminants that are naturally fed into the sorting zone. As the rotor rotates and the movement of the metal strips displaces contaminants and fibers from the inner surface of the pressure screen cylinder, the displaced contaminants and fibers may collect on the leading edge of the struts, at the tips of the struts where the struts connect to the metal strips. The fibers and contaminants captured on the leading edge of the struts may accumulate more fibers and solids, and the pile on the leading edge of the struts may continue to build up. The build-up of solid contaminants and fibers may extend to the leading edge of the metal strips. This phenomenon is called stringing and may increase rotor drag and increase the motor power required to rotate the rotor. Contaminant and fiber buildup on the strut forward edge near the metal strip and on the leading edge of the metal strip can also interfere with the flow passing under the metal strip and adversely affect the pressure pulse generated by the underside of the metal strip as it passes around the inner surface of the pressure screen cylinder, which can reduce the effectiveness of the metal strip in displacing contaminant and entangled fibers from the inner surface of the pressure screen cylinder and reduce the capacity of the pressure screen cylinder. [Means for solving the problem]

[0007] Thus, there is currently a need for a rotor for a pressure screen cylinder that reduces stringing and maintains the effectiveness of the metal strip in removing contaminants and entangled fibers from the inner surface of the pressure screen cylinder and reducing rotor drag. The pressure screen rotor of the present disclosure meets this need and solves these problems by incorporating forward moving vanes that extend between the rotor hub and the metal strip. The forward moving vanes reduce the severity of the corners where the forward moving vanes join the metal strip, and the fluid forces they create create a flow or flow field that moves displaced fibers and contaminants from the pressure screen cylinder or normal local flow field inward toward the hub of the rotor (without allowing the contaminants and fibers to collect on the vane leading edge closest to the metal strip and / or the leading edge of the metal strip). The forward moving vanes can be made thinner than other alternative methods to reduce stringing, and the thinner forward moving vanes disclosed herein can reduce drag due to their reduced cross-sectional area. The forward moving blades reduce the build-up of contaminants and fibers on the outer portions of the leading edge of the blade and / or on the leading edge of the metal strip because the flow created by the forward moving blades carries the contaminants and fibers inward.

[0008] The pressure cylinder rotors disclosed herein may also have a release area located at or nearest the point where the vane connects to the rotor hub. The release area is the area of ​​the vane closest to the inner end of the vane and has a thickness greater than the thickness of the vane. The greater thickness of the release area allows the vane leading edge at the inner end of the vane to have a greater radius of curvature so that contaminants and fibers are not trapped on the leading edge of the vane where the vane is attached to the hub. The contaminants and fibers instead slide over the leading edge of the vane and back into the fiber suspension. Also, due to the forward shape of the leading edge, any fibers moving inwardly along the leading edge of the vane will encounter a local thickening in the release area of ​​the vane and slide off the leading edge of the vane.

[0009] According to one or more aspects of the present disclosure, a rotor for a pressure screen cylinder for removing contaminants from a solid suspension may include a cylindrical hub, a plurality of metal strips spaced radially outward from the hub, and a plurality of vanes connecting the plurality of metal strips to the hub, each vane being an advancing vane having a leading edge.

[0010] According to one or more aspects of the present disclosure, a pressure separation system for removing contaminants from a solid suspension or body may include a pressure screen cylinder having a plurality of openings, a rotor according to any aspect disclosed herein, and a drive motor operably coupled to the rotor, the rotor may be disposed within the pressure screen cylinder, and the drive motor may be configured to rotate the rotor relative to the pressure screen cylinder.

[0011] According to yet another aspect of the present disclosure, a method for removing solid contaminants from a solid suspension or solid suspension may include contacting the solid suspension or solid suspension with a pressure screen cylinder having a cylindrical wall, the cylindrical wall having an inner surface, an outer surface, and a plurality of openings extending from the inner surface to the outer surface. Contact of the solid suspension with the pressure screen cylinder may cause at least a portion of the solid suspension or solid suspension to pass through the plurality of openings. The method may further include rotating a rotor disposed within the pressure screen cylinder. The rotor may include a cylindrical hub, a plurality of metal strips spaced radially outward from the hub, and a plurality of vanes connecting the plurality of metal strips to the hub. Each of the metal strips may be radially spaced from the inner surface of the cylindrical wall, and each of the vanes may be an advancing vane having a leading edge with a tip located more than 50% forward of another portion of the leading edge relative to a direction of rotation of the rotor. Rotation of the rotor may create pressure pulses in each of the metal strips that dislodge solid contaminants and fibers entangled on the inner surface of the pressure screen cylinder. The advancing vanes may create a flow and / or flow field that moves solid contaminants and fibers inwardly and prevents solid contaminants and fibers from accumulating on the leading edges of the vanes and / or the leading edges of the metal strips. The method may further include collecting acceptable solid suspension from the plurality of openings in the pressure screen cylinder.

[0012] It should be understood that both the foregoing general description and the following detailed description are intended to provide an overview or framework for understanding the nature and character of the various embodiments and claimed subject matter.

[0013] The accompanying drawings are included to provide a further understanding of the various embodiments, and are incorporated in and constitute a part of this specification. The drawings illustrate various embodiments described herein, and together with the description, serve to explain the principles and operation of the claimed subject matter. [Brief description of the drawings]

[0014] [Figure 1]1 illustrates a schematic front perspective view of a pressure screen cylinder and a rotor disposed within the pressure screen cylinder in accordance with one or more embodiments shown and described herein, the pressure screen cylinder being shown in partial cross-section. [Diagram 2] FIG. 2 illustrates a schematic front perspective view of the pressure screen cylinder of FIG. 1 according to one or more embodiments shown and described herein. [Diagram 3] 2 illustrates a schematic diagram of a front perspective view of the rotor of FIG. 1 according to one or more embodiments shown and described herein. [Figure 4] 1A and 1B illustrate schematic diagrams of a top view of an embodiment of a rotor for a pressure screen cylinder according to one or more embodiments shown and described herein. [Diagram 5] 1 illustrates a schematic top view of a conventional rotor of the prior art; [Figure 6] 6 illustrates diagrammatically the build-up of contaminants and fibers on the leading edge of the strut of the conventional rotor of FIG. 5 . [Figure 7] FIG. 5 illustrates a schematic diagram of a top view of the rotor blades of FIGS. 3 and 4 according to one or more embodiments shown and described herein. [Figure 8] 2A and 2B illustrate schematic diagrams of a top view of another embodiment of a rotor blade according to one or more embodiments shown and described herein. [Figure 9A] 9A-9C are schematic diagrams illustrating a cross-sectional view of a vane taken along line 9-9 of FIG. 7 according to one or more embodiments shown and described herein. [Figure 9B] 2A and 2B illustrate schematic cross-sectional views of a leading edge of a vane having an asymmetric front surface according to one or more embodiments shown and described herein; [Figure 10] 2A and 2B illustrate schematic diagrams of a top perspective view of another embodiment of a rotor and pressure screen cylinder according to one or more embodiments shown and described herein. [Figure 11] 11 illustrates a schematic diagram of a top view of a portion of the rotor of FIG. 10 according to one or more embodiments shown and described herein. [Figure 12] 12 illustrates a schematic diagram of a front view of a portion of the rotor of FIG. 11 according to one or more embodiments shown and described herein. [Figure 13]12 illustrates a schematic side view of a portion of the rotor of FIG. 11 according to one or more embodiments shown and described herein. [Figure 14] 1A and 1B are schematic illustrations of a front perspective view of a modeled rotor in an example embodiment according to one or more embodiments shown and described herein; [Figure 15] 15A-15C are schematic diagrams illustrating a top view of the rotor of FIG. 14 according to one or more embodiments shown and described herein. [Figure 16] 1 graphically illustrates a model simulation of streamlines near the surface of a rotor having forward-swept blades according to one or more embodiments shown and described herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a rotor for a pressure screen cylinder will now be described in detail, examples of which are illustrated in the accompanying drawings, in which the same reference numbers will be used throughout the drawings, whenever possible, to refer to the same or like parts.

[0016] Referring to FIG. 1, one embodiment of a pressure separator for removing solid contaminants from a solid suspension or suspension according to the present disclosure is shown. The pressure separator includes a pressure screen cylinder 10 and a rotor 100 disposed within the pressure screen cylinder 10. The rotor 100 includes a cylindrical hub 110, a plurality of metal strips 120 spaced radially outward from the hub 110, and a plurality of vanes 140 connecting the plurality of metal strips 120 to the hub 110. Each vane 140 is an advancing vane having a leading edge 146. The leading edge 146 may be curved such that a tip 144 of the vane's leading edge 146 is located further forward relative to the direction of rotation 102 of the rotor 100 than a greater portion (e.g., more than 50%) of the remaining leading edge 146 of the vane 140. As previously discussed, the advancing vanes 140 of the present disclosure may reduce stringing (e.g., accumulation of contaminants and fibers at the tip 144 of the vane 140). Reducing stringing reduces drag and the power required to rotate the rotor 100, and prevents stringing caused by a reduced effectiveness of the metal strips 120 in creating pressure pulses against the inner surface 14 of the pressure screen cylinder 10 and displacing contaminants and fibers.

[0017] Unless expressly stated otherwise, it is never intended that any method disclosed herein be construed as requiring that its steps be performed in a particular order, nor that any particular orientation of any apparatus be required. Thus, where a method claim does not actually specify the order in which its steps are to be followed, or an apparatus claim does not actually specify the order or orientation of individual parts, or where neither the claims nor the description specify that the steps are to be limited to a particular order, or a particular order or orientation of parts of the apparatus, it is never intended that an order or orientation be inferred in any respect. This applies to any possible implicit basis for interpretation, including logical considerations regarding the sequence of steps, operational flow, order of parts, or orientation of parts, plain meaning derived from grammatical constructions or punctuation, and the number or type of embodiments described herein.

[0018] The directional terms used in this document, e.g., upper, lower, right, left, front, back, top, and bottom, are used only with reference to the depicted figures and the coordinate axes provided therein, and are not intended to imply absolute directions.

[0019] As used herein, the English singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to one element includes aspects having two or more such elements unless the context clearly dictates otherwise.

[0020] As used herein, the terms “longitudinal” and “axial” refer to an orientation or direction generally parallel to the central axis A of the pressure screen cylinder and / or the axis of rotation B of the rotor 100 .

[0021] As used herein, the term "radial" refers to a direction along any radial line extending outward from the central axis A of the pressure screen cylinder (FIG. 1) and / or the axis of rotation B of the rotor 100.

[0022] As used herein, the terms "upstream" and "downstream" refer to the relative location of features with respect to the direction of flow of the solids suspension or suspension. In the case of the screen cylinder of the present disclosure, the flow of the solids suspension generally flows from inside the pressure screen cylinder radially outward through the openings in the pressure screen cylinder to the outer surface of the pressure screen cylinder.

[0023] As used herein, the terms "solid contaminant" and "oversized solid contaminant" refer to undesirable solid objects that are not intended to be present in a solid suspension or suspension and that can be distinguished from solid components such as fibers that are intended to be present in the solid suspension, e.g., pieces of wood, metal, dried glue, string, or other contaminants.

[0024] As used herein, the terms "forward" and "aft" refer to locations on an object relative to the direction of movement of the object, with forward being in the direction of movement and aft being opposite to the direction of movement. The term "forward edge" of a blade disclosed herein refers to the edge of the blade facing the direction of rotation of the rotor, and the term "aft edge" of a blade refers to the edge of the blade facing away from the direction of rotation of the blade.

[0025] As used herein, the term "inward" refers to the radial direction toward the hub of the rotor, and the term "outward" refers to the direction radially outward away from the hub.

[0026] As used herein, the term "leading edge" refers to the edge of the rotor metal strip that faces in the direction of rotor rotation, and the term "trailing edge" refers to the edge of the rotor metal strip that faces away from the direction of rotor rotation.

[0027] As used herein, the term "advancing" refers to the shape of the leading edge of the blade where at least a portion of the tip of the leading edge of the blade is forward of another portion of the leading edge proximate the inboard end of the blade relative to the direction of rotation of the rotor.

[0028] As used herein, the term "match" means to match exactly when superimposed.

[0029] In the paper and pulp industry, pulp screening can be accomplished by a pressure screening process using a screen cylinder. The pressure screening process can involve feeding a solid suspension, such as a solid suspension of fibers, into a pressure screen cylinder. The fibers can be any type of fiber, such as but not limited to cellulose fibers, cotton, glass fibers, or other fibers. The screen cylinder can be an outward flow screen cylinder, where an acceptable portion of the solid suspension flows radially outward through the screen cylinder.

[0030] 1, one embodiment of a pressure screen cylinder 10 with a rotor 100 of the present disclosure is depicted generally. The pressure screen cylinder 10 comprises a cylindrical wall 12 having an inner surface 14 and an outer surface 16. The cylindrical wall 12 has a plurality of openings that extend radially through the cylindrical wall 12 from the inner surface 14 to the outer surface 16. In an embodiment, the cylindrical wall 12 may be a unitary cylindrical wall comprised of a metal cylinder that is perforated or slotted to provide generally radial openings through the cylindrical wall 12.

[0031] Referring to FIG. 2, in embodiments, the cylindrical wall 12 of the pressure screen cylinder may comprise a plurality of longitudinally arranged shaped bars 18 that define a plurality of slots along the length of the screen cylinder. In these embodiments, the shaped bars 18 may be coupled at their mounting ends to at least one support ring 20. In some embodiments, the pressure screen cylinder 10 may include a plurality of support rings 20. The pressure screen cylinder 10 may also include annular end flanges 22 at both axial ends. Each shaped bar 18 is longitudinally aligned with the central axis A of the pressure screen cylinder 10 and with the other shaped bars 18 (e.g., parallel to the central axis A of the pressure screen cylinder 10). The plurality of shaped bars 18 may be arranged side-by-side along the circular inner or outer circumference of the support ring 20 to form the cylindrical wall 12. The cylindrical wall 12 formed by the plurality of shaped bars 18 may include slots defined between each adjacent pair of shaped bars 18. The slots may extend the length of the pressure screen cylinder 10 between both annular end flanges 22. Additional features and aspects of the support structure and operation of the pressure screen cylinder 10 of the present disclosure may be found in U.S. Patent No. 8,469,198, the entire contents of which are incorporated herein by reference. The pressure screen cylinder 10 is depicted in Figures 1 and 2 as an outward flow pressure screen cylinder, in which the acceptable solid suspension flows radially outward through slots defined between the shaped bars 18. The pressure screen cylinder 10 may be operable to separate solid contaminants from the solid suspension. Other configurations of the pressure screen cylinder 10 are contemplated, so long as the pressure screen cylinder 10 comprises a cylindrical wall 12 having an inner surface on which solid contaminants and oversized fibers accumulate in a mat during operation of the pressure screen cylinder 10.

[0032] Referring again to Figure 1, the rotor 100 is disposed within the pressure screen cylinder 10. The rotor 100 comprises a hub 110, a plurality of metal strips 120 spaced radially outward from the hub 110, and a plurality of vanes 140 connecting each metal strip 120 to the hub 110. The rotor 100 is operatively coupled to a rotor drive motor (not shown) that operates to rotate the rotor 100 within the pressure screen cylinder 10. The rotor 100 rotates in a rotational direction (102) relative to the pressure screen cylinder 10. The rotor 100 has an axis of rotation B. The axis of rotation B of the rotor 100 generally coincides with a central axis A of the pressure screen cylinder.

[0033] 1, the hub 110 may be a cylindrical hub centered about the axis of rotation B of the rotor 100. The hub 110 may be a solid shaft or a hollow cylindrical shaft. The hub 110 has a base end 114 that is operably coupled to a rotor drive motor and a distal end 116 that enters the pressure screen cylinder 10. The hub 110 may be operably coupled to a rotor drive motor (not shown) to rotate the rotor 100 relative to the pressure screen cylinder 10. The hub 110 has an outer surface 112 that faces radially outwardly from the inner surface 14 of the pressure screen cylinder 10.

[0034] 3, the rotor 100 includes a plurality of metal strips 120 spaced radially from a hub 110, and as the rotor 100 rotates, the metal strips 120 travel along the inner surface 14 of the pressure screen cylinder 10. In some embodiments, each metal strip 120 may have a wing cross-sectional shape. Each metal strip 120 has a leading edge 122 facing the direction of rotation (102) and a trailing edge 124 facing in the opposite direction to the leading edge 122. In some embodiments, each metal strip 120 may have a rounded or semicircular leading edge 122 and a tapered trailing edge 124. However, it will be understood that the leading edge 122 and the trailing edge 124 of the metal strips 120 may have any shape effective to generate a pressure pulse at the inner surface 14 of the pressure screen cylinder 10, and the scope of the present disclosure is not intended to be limited by the cross-sectional shape of the metal strips 120. Each metal strip 120 has an inner surface 126 facing radially inward toward the hub 110 and an outer surface 128 facing radially outward toward the inner surface 14 of the pressure screen cylinder 10. Referring to FIG. 4, the metal strips 120 are arranged radially, with a gap G between the outer surface 128 of the metal strip 120 and the inner surface 14 of the cylindrical wall 12 of the pressure screen cylinder 10 having a minimum distance of about 1 mm to about 15 mm, e.g., about 2 mm to about 10 mm. The gap G may be greater or less than the above range without reducing the effectiveness of the rotor shape design described herein. The gap G defined between the outer surface 128 of the metal strip 120 and the inner surface 14 of the cylindrical wall 12 may be referred to as a screen action zone.

[0035] 3, each metal strip 120 may be oriented generally vertically, with an acute angle C between a leading edge 122 of the metal strip 120 and a line S parallel to the axis of rotation B and intersecting the leading edge 122 being about 40 degrees or less, about 30 degrees or less, or even about 20 degrees or less. In some embodiments, the metal strips 120 may be tilted such that the acute angle C is greater than zero and less than or equal to 40 degrees. When the metal strips 120 are tilted, each metal strip 120 may be slightly helical such that the gap G between the outer surface 128 of the metal strip 120 and the inner surface 14 of the pressure screen cylinder 10 is the same along the entire length of the metal strip 120. In some embodiments, the metal strips 120 may be vertical such that the leading edge 122 of the metal strip 120 is parallel to the axis of rotation B of the rotor 100 (e.g., the angle θ is zero).

[0036] The rotor 100 may have a sufficient number of metal strips 120 to free entangled solid contaminants and fibers from the inner surface 14 of the pressure screen cylinder 10 and prevent the pressure screen cylinder 10 from becoming partially or completely blocked by the solid contaminants and fibers. The rotor 100 may have four or more metal strips 120, for example, 4, 5, 6, 7, 8, 9, or more than nine metal strips 120.

[0037] 3 and 4, each metal strip 120 is coupled to the hub 110 by a vane 140. As used herein, the term "vane" refers to a structure that couples the metal strip 120 to the hub 110 of the rotor 100 or to a hub portion of a vane ring that is directly connected to the hub 110. A vane may consist of an arm, fin, bar, blade, rod, or other structure that extends radially outward from the hub 110 or the hub portion 162 of the vane ring 160 to the metal strip 120. Each vane 140 is directly connected to the inner surface 126 of the metal strip 120 at a tip 144 and is coupled to the hub 110 at an inner end 142 of the vane 140. In some embodiments, the vane 140 may be directly connected to the outer surface 112 of the hub 110. In other embodiments, the rotor 100 may include multiple vane rings 160 connected directly to the outer surface 112 of the hub 110, and the vanes 140 may extend radially outward from the vane rings 160 to the metal strips 120. The vanes 140 couple the metal strips 120 to the hub 110, and during operation of the pressure screen cylinder 10, the metal strips 120 rotate with the hub 110 while allowing the suspension or solid suspension to flow axially through the center of the pressure screen cylinder 10. In some embodiments, each metal strip 120 may be coupled to the hub 110 by two or more vanes 140, or three or more vanes 140.

[0038] Referring again to FIG. 1, during operation of the pressure screen cylinder 10, a suspension is axially introduced into the interior of the pressure screen cylinder 10. The suspension can be a suspension including paper-making pulp fibers dispersed in a liquid medium, such as water, although the pressure screen cylinder 10 and rotor 100 of the present disclosure are not intended to be so limited. The flow of solid suspension or suspension into the pressure screen cylinder 10 causes the liquid medium and fibers below a threshold size to pass through the openings in the cylindrical wall 12 of the pressure screen cylinder 10. Contaminants and fibers that are too large for the paper-making process do not pass through the openings in the cylindrical wall 12 and collect on the inner surface 14 of the cylindrical wall 12 of the pressure screen cylinder 10. The collected solid contaminants and fibers can form a layer on the inner surface 14 of the cylindrical wall 12, reducing or preventing the acceptable flow of suspension through the openings in the cylindrical wall 12 of the pressure screen cylinder 10.

[0039] During operation, the rotor 100 rotates within the pressure screen cylinder 10. The rotation of the rotor 100 moves a number of metal strips 120 circumferentially around the inner surface 14 of the cylindrical wall 12 of the pressure screen cylinder 10. The movement of the metal strips 120 along the inner surface 14 of the pressure screen cylinder 10 creates pressure pulses within the screen action zone that act to remove solid contaminants and fibers that have accumulated on the inner surface 14 of the pressure screen cylinder 10. The removal of the accumulated solid contaminants and fibers reduces or prevents blockage of the openings of the pressure screen cylinder 10 by contaminants and reintroduces them into the incoming suspension or solids suspension. The solid contaminants displaced from the pressure screen cylinder 10 by the rotor metal strips 120 and the rejected oversized fibers flow to the outlet of the pressure screen cylinder 10 and are removed from the system. Acceptable fibers released from the inner surface 14 fall back into the incoming suspension or solids suspension and may be re-introduced into the pressure screen cylinder 10 for another opportunity to pass through the openings and enter the receiving outlet.

[0040] Referring to Figure 5, an example of a conventional rotor 200 for a pressure screen cylinder 10 is illustrated generally in top view. In the conventional rotor 200 of Figure 5, the struts 240 that connect the metal strips 220 to the hub 210 are bars that extend radially outwardly along straight lines from the hub 210 to the metal strips 220. These struts 240 have a straight leading edge that is generally perpendicular to the metal strips 220 at the tips 244 of the struts 240.

[0041] During operation of the pressure screen cylinder and rotor, the rotor rotates and the movement of the metal strip displaces contaminants and fibers from the inner surface 14 of the pressure screen cylinder 10. Referring to FIG. 6, the conventional rotor 200 of FIG. 5 is depicted in a top view. As shown in FIG. 6, the displaced contaminants and fibers may accumulate on the leading edge 246 of the strut 240, particularly where the strut 240 joins the metal strip 220 (e.g., the tip 244 of the strut 240). The fibers and contaminants initially captured on the leading edge 246 of the strut 240 may accumulate more contaminants and fibers, and the buildup on the leading edge 246 of the strut may continue to build up on the strut 240 and on the leading edge of the metal strip 220. This phenomenon is referred to as stringing. The accumulation 400 of solid contaminants and fibers due to stringing may increase rotor drag, increasing the motor power required to rotate the rotor 200. The build-up 400 of contaminant and fiber pile-up near the metal strip 220 and on the leading edge of the metal strip 220 on the leading edge 246 of the support 240 may also impede the pressure pulse generated by the leading edge of the metal strip 220 and reduce the effectiveness of the metal strip 220 in displacing contaminant and tangled fibers from the inner surface 14 of the pressure screen cylinder 10.

[0042] The thickness of the struts 240 at the tips 244 may be increased to reduce build-up of solid contaminants and fibers on the leading edge 246 of the struts 240. For example, increasing the thickness of the struts 240 to 1.5 inches (about 38 mm) or more such that the radius of curvature of the leading edge of the struts 240 is about 0.75 inches (about 19 mm) or more may reduce the tendency of solid contaminants and fibers to become trapped on the leading edge 246 of the struts 240 at the tips 244. However, increasing the thickness of the struts 240 at the tips 244 increases the drag caused by movement of the struts 240 through the suspension during operation. The increased drag of the struts 240 may significantly increase the power load required to rotate the rotor 200.

[0043] 3 and 4, the rotor 100 of the present disclosure solves these problems by incorporating forward struts, the vanes 140. The forward-progressing geometry design of the vanes 140 disclosed herein creates a flow field around the leading edge 146 of the vanes 140 that carries inward (e.g., radially inward toward the hub 110) solid contaminants and fibers that are displaced from the pressure screen cylinder 10 or from the normal flow field around the vanes 140. The forward-progressing geometry design of the vanes 140 that moves the solid contaminants and fibers inward may reduce or prevent build-up of contaminants and fibers on the leading edge 146 of the vanes 140 and / or on the leading edge 122 of the metal strip 120. This in turn may reduce or prevent the accumulation of solid contaminants and fibers from interfering with the pressure pulses generated by the passage of the metal strips 120 along the inner surface 14 of the pressure screen cylinder 10, reducing drag on the vanes 140 caused by build-up of contaminants and fibers on the tips 244 of the vanes 140. The forward profile design of the vanes 140 disclosed herein may also allow the vanes 140 to be made thinner, further reducing drag caused by movement of the vanes 140 through the solid suspension or body.

[0044] 3 and 4, as previously described, the rotor 100 comprises a hub 110, a plurality of metal strips 120, and a plurality of vanes 140 coupling the plurality of metal strips 120 to the hub 110. In some embodiments, the rotor 100 may comprise a plurality of vane rings 160 coupled to the hub 110, each vane ring 160 comprising a hub portion 162, and each vane 140 may extend radially outward from the hub portion 162 of the vane ring 160 to the metal strips 120. The hub portion 162 may be an annular disk coupled to the hub 110 at a radially inner edge 164 and coupled to the plurality of vanes 140 at a radially outer edge 166. In some embodiments, the vanes 140 may be directly coupled to the hub 110 at the inner ends 142 of the vanes 140.

[0045] 7, the blade 140 disclosed herein has a forwardly shaped leading edge 146. A forwardly shaped leading edge 146 generally means that the leading edge 146 of the blade 140 is shaped such that the leading edge 146 at the tip 144 of the blade 140 is forward of the remainder of the leading edge 146 relative to the direction of rotation 102 of the rotor 100. In some embodiments, the leading edge 146 of the blade 140 is shaped such that the leading edge 146 at the tip 144 of the blade 140 is forward of most of the remainder of the leading edge 146 relative to the direction of rotation 102 of the rotor 100. The forward shape of the leading edge 146 of the blade 140 is not intended to refer to any forward material protrusion (simply associated with bonding the blade 140 to the metal strip 120 or hub 110) at or adjacent (e.g., within less than 1 cm) the tip 144 of the blade 140.

[0046] The leading edge 146 of the blade 140 is aligned with a point P OUT The leading edge 146 of the blade 140 may have a shape such that the leading edge 146 is forward of most of the other portions of the leading edge 146 with respect to the direction of rotation 102 of the rotor 100. The leading edge 146 of the blade 140 may have a shape such that the leading edge 146 is forward of the tip 144 of the blade 140. OUT The leading edge 146 of the blade 140 may be shaped such that the leading edge 146 is located 50% or more, 75% or more, or 90% or more forward of the remaining portion of the leading edge 146 with respect to the direction of rotation 102 of the rotor 100. The leading edge 146 of the blade 140 may be shaped such that the leading edge 146 is located at a point on the leading edge 146 at the tip 144 of the blade 140 (e.g., point P OUT) may be curved such that the leading edge 146 is 50% or more, 75% or more, or 90% or more forward of the remaining portion of the leading edge 146 relative to the direction of rotation 102 of the rotor 100. In some embodiments, the leading edge 146 of the blade 140 has a concave curvature. In some embodiments, 25% or more, 35% or more, 50% or more, or 90% or more of the leading edge 146 of the blade 140 has a concave curvature. In some embodiments, the leading edge 146 of the blade 140 is continuously curved from the tip 144 to the inner end 142. Here, the curvature of the leading edge 146 refers to the curvature in a horizontal plane, meaning that the curvature of the leading edge is in a plane perpendicular to the axis of rotation of the rotor and passing radially through the blade 140. In some embodiments, the radius of curvature of the leading edge 146 may increase as the radial distance between a point on the leading edge 146 of the blade 140 and the axis of rotation 102 of the rotor 100 decreases. 7, in some embodiments, at least a portion of the leading edge 146 of the vane 140 may be straight (i.e., extends along a straight line rather than a curve) and angled such that the tip 144 is forward of the inboard end 142 of the leading edge 146. In some embodiments, 50% or more, 75% or more, 85% or more, 90% or more, 95% or more, or 98% or more of the leading edge 146 of the vane 140 is straight (i.e., extends along a straight line rather than a curve).

[0047] Referring again to FIG. 7, point P on wing 140 IN is the point where the forward edge 146 of the vane 140 is connected to the hub 110 or to the hub portion 162 of the vane ring 160 at the inner end 142. OUT is the point on the vane 140 where the leading edge 146 of the vane 140 connects to the metal strip 120 at the tip 144 of the vane 140. IN is centered on the rotation axis B of the rotor 100 and is located at the inner end 142 of the front edge 146 of the blade 140 at point P IN is the radius of the circle that passes through. OUT is centered on the rotation axis B of the rotor 100 and reaches the tip 144 of the front edge 146 of the blade 140 at point P OUT is the radius of the circle that passes through point P (for example, point P1 or point P2). IN and point P OUTThe radius R is the radius of a circle that is centered on the axis of rotation B of the rotor 100 and passes through the point P on the leading edge 146 of the blade 140.

[0048] Referring to FIG. 7, the first point P1 is a point P IN and point P OUT The second point P2 is any point on the leading edge 146 of the blade 140 between the points P1 and P2, and the radius R1 is the radius of a circle centered on the axis of rotation B of the rotor 100 and passing through the point P1. IN and point P OUT and radius R2 is the radius of a circle that is centered on the axis of rotation B of the rotor 100 and passes through point P2. OUT The radial line D passing through P1 and the radial line E passing through P1 form an angle α1, OUT A radial line D through point P2 and a radial line F through point P2 form an angle α2. In some embodiments, when radius R2 is greater than radius R1 and angle α2 is less than angle α1, leading edge 146 of vane 140 may be considered to have an advanced shape. Angles α1 and α2 are measured counterclockwise from line D to line E or line F in FIG. 7 ... IN and point P OUT The leading edge 146 of the blade 140 may be considered to have an advanced shape if point P2 is separated from P1 by 5% or more, 10% or more, or 15% or more of the distance along the leading edge 146 between P1 and P2.

[0049] In some embodiments, a point P on the leading edge 146 of the blade 140 OUT is located in front of point P in the direction of rotation 102 of the rotor 100, and point P is located on the leading edge 146 of the blade 140 with a radius R of (R IN +((R OUT -R IN In some embodiments, the point P on the leading edge 146 of the tip 144 of the blade 140 is greater than or equal to OUT is a point P of the inner end 142 of the front edge 146 IN In some embodiments, a point P on the leading edge 146 at the tip 144 of the blade 140 OUT is the point P INand point P OUT 1. The vane 140 is located forward of point P at all positions of point P on the leading edge 146 of the vane 140 between the positions.

[0050] Referring again to FIG. 7, in some embodiments, point P is spaced apart from leading edge 146 (R IN +((R OUT -R IN ) / 2)) at the intersection of point P with a circle of radius R equal to OUT may be located 5 degrees or more, 10 degrees or more, 15 degrees or more, or 20 degrees or more, for example, 5 degrees to 50 degrees, forward of point P with respect to the rotation direction of the rotor 100. In other words, extending from the rotation axis B to point P OUT A radial line D passing through the point P1 and a radial line E extending from the axis of rotation B and passing through the point P1 form an angle α1. In some embodiments, the point P is in the range of 0° to 30°. IN +((R OUT -R IN ) / 2)) at the intersection of point P with a circle of radius R equal to OUT is forward of point P relative to the direction of rotation, and angle α1 can be 3 degrees or more, 5 degrees or more, 10 degrees or more, 15 degrees or more, or 20 degrees or more, for example, from 3 degrees to 50 degrees. OUT Therefore, at least a point P (with a radius R of (R IN +((R OUT -R IN In some embodiments, the leading edge 146 of the vane 140 may be curved such that the angle α increases as the radius R decreases to a point P OUT From point P IN In some embodiments, the leading edge 146 of the vane 140 is curved such that the angle α increases as the leading edge 146 decreases to a point P OUT From the point P on the front edge 146, the radius R of the circle that passes through the point P and has the rotation axis B of the rotor 100 as its center is (R IN +((R OUT -R IN ) / 2)) or less).

[0051] 8, in some embodiments, the leading edge 146 of the vane 140 may be considered to have a forward curved shape even though the leading edge 146 of the vane 140 curves back forward near the inboard end 142 of the vane 140. In the embodiment depicted diagrammatically in FIG. 8, point P3 is shown to be located on the leading edge 146 of the vane 140 near the inboard end 142. As indicated by the smaller radial distance and the significantly larger angle α3 from P3 to the axis of rotation B, points P3 and P IN is in front of points P1 and P2. Points P3 and P IN Also, point P OUT However, P2 is in front of P1, and P OUT Because leading edge 146 of blade 140 is forward of both P1 and P2, leading edge 146 of blade 140 is still considered to be in an advanced configuration. Thus, leading edge 146 of blade 140 has an advanced configuration even though only the portion of leading edge 146 closest to the tip of blade 140 slopes or curves forward with increasing radial distance to axis of rotation B.

[0052] As previously discussed, the forward-moving shape of the vane 140 may reduce the tendency of contaminants and fibers to become trapped on the leading edge 146 of the vane 140, allowing the thickness of the vane to be reduced. Referring to FIG. 9A, a cross-section of an embodiment of a vane 140 taken along reference line 9-9 of FIG. 7 is illustrated generally. In some embodiments, the vane 140 has a thickness T of less than 1.5 inches (38 mm), e.g., from 0.25 inches (6.4 mm) to less than 1.5 inches (38 mm), or from 0.5 inches (12.7 mm) to 1.25 inches (about 32 mm). S The forward profile design of the blade 140 disclosed herein may provide greater flexibility in determining the thickness of the blade 140 to balance drag and stringing.

[0053] In some embodiments, the leading edge 146 of the vane 140 has a front surface 150 that extends from a top surface 152 of the vane 140 to a bottom surface 154 of the vane 140. The cross-sectional shape of the front surface 150 may be any shape, and the present disclosure is not intended to be limited by the cross-sectional shape of the front surface 150. The following embodiment depicted in Figures 9A and 9B is for purposes of illustrating the relationship between thickness, radius of curvature of the front surface 150, and stringing. In some embodiments, as shown in Figure 9A, the front surface 150 may have a semicircular shape with a radius of curvature ε of less than about 0.75 inches (19 mm), 0.5 inches (12.7 mm) or less, 0.4 inches (10.2 mm) or less, 0.3 inches (7.6 mm) or less, or 0.25 inches (6.35 mm) or less, for example, 0.1 inches (2.5 mm) to 0.75 inches. The radius of curvature ε of the front surface 150 refers to the radius of a circle H having an arc that matches the semicircular contour of the front surface 150 in a vertical plane (e.g., a plane parallel to the Z axis in FIG. 9A and vertically bisecting the blade 140). The trailing edge 148 is shown in FIG. 9A as having a tapered shape. However, it will be understood that the trailing edge 148 may have any suitable shape, including a semicircular shape or other shapes. The contour of the trailing edge 148 does not affect the stringing.

[0054] 9B, in some embodiments, the front surface 150 of the leading edge 146 of the vane 140 may have a non-semicircular shape. In some embodiments, the front surface 150 of the leading edge 146 may have an asymmetric shape, such as, but not limited to, two or more portions with different radii of curvature. The asymmetric shape of the front surface 150 of the vane 140 may further aid in reducing build-up of solid contaminants and fibers on the leading edge 146 of the vane 140. With a symmetric shape, such as a semicircular shape, of the front surface 150, the forces on the solid contaminants and fibers trapped on the leading edge 146 may be balanced and tend to keep the solid contaminants and fibers trapped on the leading edge 146. On the other hand, the asymmetric shape of the front surface 150 may not balance the forces acting on the solid contaminants and fibers trapped on the leading edge 146. In particular, the asymmetric shape of the front surface 150 alters the flow path around the leading edge 146 of the vane 140 such that the velocity of the fluid across the top surface 152 of the vane 140 may be different than the velocity of the fluid below the bottom surface 154 of the vane 140. The difference in fluid velocity above and below the vane 140 may cause the forces exerted by the fluid flow on solid contaminants and fibers to be greater on one side of the vane 140, tending to pull the solid contaminants and fibers away from the leading edge 146 of the vane 140.

[0055] 9B, the forward surface 150 may have a first portion 156 and a second portion 158. The first portion 156 may have a first radius of curvature that corresponds to a radius of a circle H1 that corresponds to the first portion 156. The second portion 158 may have a second radius of curvature that corresponds to a radius of a circle H2 that corresponds to the second portion 158, the second radius of curvature being different than the first radius of curvature. Other contour shapes of the forward surface 150 of the leading edge 146 of the vane 140 are contemplated.

[0056] The advancing vanes 140 create streamlines that carry material inwardly towards the hub 110. Thus, during operation, the advancing vanes 140 move solid contaminants and fibers dislodged from the inner surface 14 of the pressure screen cylinder 10 or within the normal flow field around the vanes 140 inwardly towards the inner ends 142 of the vanes 140 and the hub 110, without accumulating on the leading edges 146 at the tips 144 of the vanes 140 or on the leading edges 122 of the metal strips 120. In some embodiments, some solid contaminants and fibers may still be trapped in a wedge-shaped pocket at point P1 where the inner ends 142 of the vanes 140 are joined to the hub 110 or the hub portion 162 of the vane ring 160. The build-up of contaminants and fibers near the inner ends 142 of the vanes 140 is less of a problem because the build-up at the inner ends 142 of the vanes 140 does not interfere with the action of the metal strip 120 generating pressure pulses against the inner surface 14 of the pressure screen cylinder 10. Also, because the build-up is closer to the axis of rotation B of the rotor 100, the linear velocity of the inner ends 142 of the vanes 140 is less than the linear velocity of the tips 144 of the vanes 140. The lower linear velocity of the inner ends 142 reduces the effect of the build-up of contaminants and fibers on the drag of the rotor 100. However, these build-ups at the inner ends 142 of the vanes 140 may still have some, but more limited, effect on the drag and the power required to rotate the rotor 100.

[0057] 10-13, in some embodiments, the rotor 100 disclosed herein may include a relief area 170 located at the inboard end 142 of each vane 140 (that is coupled to the hub 110 or the hub portion 162 of the vane ring 160). The relief area 170 may be located at the leading edge 146 of the vane 140, the relief area 170 forming at least a portion of the leading edge 146 of the vane 140 in the area where the inboard end 142 of the vane 140 is coupled to the hub 110 or the hub portion 162 of the vane ring 160. The relief area 170 may form less than 50%, no more than 30%, no more than 20%, no more than 15%, no more than 10%, or no more than 5%, for example 1% to 50%, of the leading edge 146 of the vane 140.

[0058] The relief area 170 is the thickness T of the blade 140. S Larger thickness TR The thickness T of the relief area 170 may be R may be sufficient to increase the radius of curvature ε of the leading edge 146 of the vane 140, the hub portion 162 of the vane ring 160, or both, at the point where the inboard end 142 of the vane 140 is joined to the hub 110 or the vane ring 160. In some embodiments, the relieved area 170 has a thickness T such that the radius of curvature ε of the leading edge 150 of the vane 140 at the inboard end 142 is 0.75 inches (19.1 mm) or more, 1.0 inches (25.4 mm) or more, 1.25 inches (31.8 mm) or more, or 1.5 inches (38.1 mm) or more, e.g., about 0.75 inches to 6 inches (152.4 mm). R may have.

[0059] The relief area 170 is the thickness T of the blade 140. S Larger thickness T R In some embodiments, the relief area 170 has a thickness T R is the thickness of the blade 140 T S In some embodiments, the relief area 170 has a thickness T of about 35 mm or more, greater than about 37 mm, or about 40 mm or more. R In some embodiments, as the radial distance to the axis of rotation B of the rotor 100 decreases, the thickness T S is the thickness T of the relief area 170 at the inner end 142 of the blade 140 from the minimum thickness near the tip 144 of the blade 140 R The thickness T of the relief area 170 can be increased to R may be 1.25 times or more, 1.5 times or more, 1.75 times or more, 2 times or more, 2.25 times or more, or 3 times or more the minimum thickness of the vane 140 nearest the tip 144 of the vane 140 .

[0060] The greater thickness of the release area 170 results in a greater radius of curvature ε of the vane 140 at the inner end 142 of the vane 140. The greater radius of curvature ε of the release area 170 may direct contaminant material and fibers passing along the leading edge 146 of the vane 140 radially inward from the tip 144 to the inner end 142 away from the inner end 142 of the vane 140. Solid contaminant material released from the vane 140 by the release area 170 may travel toward the outlet of the pressure screen cylinder 10 and be removed from the pressure sorting apparatus. Any acceptable fibers released by the release area 170 may be returned to the suspension or into the suspension for reintroduction into the pressure screen cylinder 10.

[0061] Referring again to FIG. 8 , in some embodiments, the leading edge 146 of the vane 140 may be forward-facing proximate the tip 144 of the vane 140, but may bend back forward proximate the inboard end 142 of the vane 140. In these embodiments, the relief area 170 may be located at the bend point of the leading edge 146. The bend point is a point on the leading edge 146 where moving inward or outward along the leading edge 146 would move forward from the bend point relative to the direction of rotation of the rotor 100. The bend point creates a pocket where solid contaminants and fibers may get trapped on the leading edge 146 of the vane 140. Providing the relief area 170 at the bend point of the leading edge 146 may help any fibers or contaminants to release and flow inward from the leading edge 146 of the vane 140.

[0062] As previously mentioned, the pressure screen cylinder 10 including the rotor 100 with advancing blades 140 may be used to process solid suspensions of cellulose or other fibers in the paper and pulp industry as previously described. However, the pressure screen cylinder 10 and rotor 100 may not be limited to use in the paper and pulp industry. For example, the pressure screen cylinder 10 and rotor 100 of the present disclosure with advancing blades 140 may be used to screen solid suspensions and / or suspensions to remove oversized solid contaminants in mining and drilling applications, food preparation and processing operations, water treatment processes, coating operations, and other industries.

[0063] Referring again to FIG. 1, in some embodiments, a method for removing oversized solid contaminants from a suspension or solids body may include contacting the suspension or solids body with a pressure screen cylinder 10 comprising a rotor 100. The pressure screen cylinder 10 may have any of the features of the pressure screen cylinder 10 described above. In particular, the pressure screen cylinder 10 may comprise a cylindrical wall 12 having an inner surface 14, an outer surface 16, and a plurality of openings extending from the inner surface 14 to the outer surface 16. Contact of the suspension or solids body with the pressure screen cylinder 10 causes at least a portion of the suspension or solids body to pass through the openings in the cylindrical wall 12. The method may further include rotating the rotor 100 disposed within the pressure screen cylinder 10. The rotor 100 may have any of the features of the rotor 100 described above. In some embodiments, the rotor 100 comprises a cylindrical hub 110, a plurality of metal strips 120 spaced radially outward from the hub 110, and a plurality of vanes 140 connecting the plurality of metal strips 120 to the hub 110. Each metal strip 120 is radially spaced from the inner surface 14 of the cylindrical wall 12. The vanes 140 are forward-moving vanes having a curved forward edge 146, a tip 144 of which is forward of an inner end 142 of the forward edge 146 relative to the direction of rotation 102 of the rotor 100. Rotation of the rotor 100 causes each metal strip 120 to generate a pressure pulse which displaces solid contaminants and fibers entangled with the inner surface 14 of the pressure screen cylinder 10. The advancing vanes 140 create fluid streamlines that move solid contaminants and fibers inwardly toward the hub 110 and prevent the solid contaminants and fibers from accumulating on the leading edge 146 of the vanes 140, the leading edge 122 of the metal strip 120, or both. The method may further include collecting the acceptable solid suspension from a plurality of openings in the pressure screen cylinder 10. The method may further include collecting the rejected solid suspension from an outlet of the pressure screen cylinder.

[0064] Working Example Embodiments of the present disclosure will be further clarified by the following examples, which should not be construed as limiting the disclosed and / or claimed embodiments.

[0065] Example 1 In Example 1, the rotation of a rotor with forward-advancing blades in a fluid is modeled using Ansys R19.2 engineering simulation software. Referring to Figures 14 and 15, the modeled rotor 100 is depicted generally in side view (Figure 14) and top view (Figure 15). The modeled rotor 100 includes nine metal strips 120 with slightly curved ends that are angled from the vertical. Each metal strip 120 is attached to the hub 110 by three vane rings 160 with vanes 140 extending radially outward from the vane rings 160 to the metal strips 120. The vanes 140 are forward-advancing in shape with the tips 144 of the leading edges 146 forward relative to the remainder of the leading edges 146. A model simulation of the rotation of the modeled rotor 100 with forward-advancing blades 140 is graphically illustrated in Figure 16. As shown in FIG. 16, the rotation of the rotor 100 and the movement of the advancing vanes 140 through the liquid creates streamlines 190 along the leading edges 146 of the vanes 140 that direct fluid and material radially inward toward the hub 110 .

[0066] Comparative Example 2: Operation of the Pressure Screen Cylinder with a Standard Rotor In Comparative Example 2, a pressure screen cylinder with a standard rotor was operated to screen paper pulp. The pressure screen cylinder had slots with a slot width of about 0.21 mm. The standard rotor of Comparative Example 2 had six metal strips, each metal strip connected to a hub by three struts extending radially between the hub and the inner surface of the metal strip. The struts were cylindrical rods extending radially between the hub and the inner surface of the metal strip (similar to the prior art depicted in FIG. 5). The cylindrical rod struts had an outer diameter of about 30 mm. The pulp suspension fed into the pressure screen cylinder of Comparative Example 2 had a nominal feed consistency of 2.8%.

[0067] The pressure screen cylinder and standard rotor were operated for an extended period to screen the pulp suspension. During operation, the rejection rate, thickening factor, drive speed and power consumption were recorded. The thickening factor was determined by measuring the consistency of the rejected suspension leaving the discharge outlet and the consistency of the feed suspension entering the screen. The thickening factor is the ratio of the consistency of the rejected suspension to the consistency of the feed suspension. The average power consumption during operation is provided in Table 1 below.

[0068] Following operation of the pressure screen cylinder, the pressure screen cylinder was stopped and the liquid was drained for inspection of the standard rotor. After inspection, the standard rotor was found to be free of stringing (i.e., the build-up of paper fibers on the leading edge of the blade adjacent to the metal strip). Thus, the standard rotor with a cylindrical bar having an outer diameter of 30 mm had sufficient curvature on the leading edge to prevent stringing.

[0069] Example 3: Operation of a pressure screen cylinder with a rotor with forward-moving blades In Example 3, the standard rotor in the pressure screen cylinder of Comparative Example 2 was replaced with a rotor with advancing blades of the present disclosure. The pressure screen cylinder with the rotor with advancing blades of Example 3 was operated to screen paper pulp. The rotor of Example 3 was similar to the rotor 100 depicted in FIG. 3. The rotor of Example 3 had seven inclined metal strips. Each metal strip was connected to a hub by three advancing blades with a thickness of 12 mm. The pulp suspension fed into the pressure screen cylinder of Comparative Example 2 had a nominal feed consistency of 2.8%.

[0070] The pressure screen cylinder and the rotor with forward-moving blades of Example 3 were operated for an extended period of time to screen the pulp suspension. During operation, the production rate, rejection rate, thickening factor, drive speed, and power consumption were recorded. The production rate was maintained the same as in Comparative Example 2. The rejection rate and thickening factor of Example 3 were comparable to those of Comparative Example 2. The average power consumption of Example 3 is provided in Table 1 below. Following operation of the pressure screen cylinder, the pressure screen cylinder was stopped and the liquid was drained for inspection of the rotor of Example 3 for stringing. After inspection, the rotor with forward-moving blades of Example 3 was found to be free of stringing.

[0071] [Table 1]

[0072] Both the standard rotor of Comparative Example 2 and the rotor with forward-advancing blades of Example 3 reduced stringing (e.g., fiber build-up on the leading edge of the blade adjacent to the metal strip). The rotor of Example 3 had one additional metal strip. One skilled in the art would expect the additional metal strip and three additional blades of the rotor of Example 3 to require more power. However, it was unexpectedly found that the average power required by the rotor of Example 3 was more than 23% less than the power required to operate the standard rotor, even with the additional metal strip. Thus, the rotor with forward-advancing blades of Example 3 eliminated the stringing problem and also provided operation with significantly less power than the standard rotor of Comparative Example 2.

[0073] Although various embodiments of a rotor 100 for a pressure screen cylinder 10 and methods for using the rotor 100 and pressure screen cylinder 10 have been described herein, it should be understood that it is contemplated that each of these embodiments and approaches may be used separately or in combination with one or more of the embodiments and approaches. It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments described herein without departing from the spirit and scope of the claimed subject matter. Accordingly, it is intended that this specification cover such modifications and variations of the various described embodiments, provided they come within the scope of the appended claims and their equivalents. [Explanation of symbols]

[0074] 10 Pressure Screen Cylinder 12 Cylindrical Wall 14. Inside 16 Exterior 18 Bar 20 Support Ring 22 Annular end flange 100 Rotor 102 Rotation direction 110 Hub 114 Hub base end 116 Hub End 120 Long metal piece 140 Feather 142 Inner end 144 Tip 146 Front edge 148 Posterior edge 160 Feather Ring

Claims

1. A rotor for a pressure screen cylinder for removing impurities from a solid suspension, The device comprises a cylindrical hub, a plurality of elongated metal pieces separated radially outward from the cylindrical hub, and a plurality of blades connecting the plurality of elongated metal pieces to the cylindrical hub. A rotor in which each of the aforementioned blades is a forward-facing blade having a leading edge.

2. The rotor according to claim 1, wherein the tip of the front edge of each of the blades is located 50% or more, 75% or more, or 90% or more forward of the front edge of the blade with respect to the rotation axis of the rotor.

3. The rotor according to claim 1, wherein the tip of the front edge of each of the blades is located in front of the inner end of the front edge of the blade with respect to the rotation axis of the rotor.

4. P ＩＮ is a point on the front edge at the inner end of each of the aforementioned wings, P ＯＵＴ is a point on the front edge at the tip of each of the aforementioned wings, R ＩＮ The rotation axis of the rotor and P ＩＮ This is the radial distance between them. R ＯＵＴ The rotation axis of the rotor and P ＯＵＴ This is the radial distance between them. P is P ＩＮ and P ＯＵＴ The point on the front edge between the two, R is the radius of the circle that has the rotation axis of the rotor as its center and passes through P. P is at a position on the leading edge, and R is at a position where R ＩＮ +( (R ＯＵＴ - R ＩＮ ) / 2)) or more, P ＯＵＴ is located in front of P with respect to the rotation direction of the rotor, the rotor according to claim 1.

5. The rotor according to claim 1, wherein the shape of the leading edge of each blade in a plane perpendicular to the rotor's axis of rotation is a straight line.

6. The rotor according to claim 1, wherein 50% or more of the front edge of each blade has a linear shape in a plane perpendicular to the rotation axis of the rotor.

7. The rotor according to claim 1, wherein the shape of the leading edge of each blade in a plane perpendicular to the rotor's axis of rotation is curved.

8. The rotor according to claim 7, wherein the radius of curvature of the front edge of each blade increases as the radial distance from the rotor's axis of rotation increases.

9. The rotor according to claim 1, wherein the shape of the front edge of each blade in a plane perpendicular to the rotor's axis of rotation is concave.

10. The rotor according to claim 9, wherein 25% or more of the front edge of each of the blades has a concave curvature.

11. The rotor according to claim 1, wherein the front surface of each of the blades has an asymmetrical shape in the vertical plane.

12. The rotor according to claim 1, further comprising open regions located at the inner ends of the plurality of blades, wherein each open region is positioned on the front edge of each blade and forms at least a portion of the front edge.

13. The rotor according to claim 12, wherein the open region has a thickness measured in the axial direction that is 1.25 times or more the thickness of each of the blades measured in the axial direction.

14. The rotor according to claim 12, wherein in the open region, the front surface of the front edge of each blade has a radius of curvature of 0.75 inches (approximately 19 mm) or more.

15. The rotor according to claim 1, wherein the tip of each blade has a thickness of 1.5 inches (approximately 38.1 mm) or less.

16. The rotor according to claim 1, wherein each of the metal segments is spirally shaped, and the acute angle between the leading edge of each metal segment and a line parallel to the rotation axis of the rotor and intersecting the leading edge of the metal segment is greater than zero degrees and less than or equal to about 40 degrees.

17. A pressure separation system for removing impurities from a solid suspension or suspended material, The device comprises a pressure screen cylinder having a plurality of openings, a rotor according to any one of claims 1 to 16 disposed within the pressure screen cylinder, and a drive motor operably coupled to the rotor. A pressure sorting system in which the drive motor is configured to rotate the rotor relative to the pressure screen cylinder.

18. The pressure screen cylinder is operable to separate solid contaminants from a solid suspension or solid agglutination, according to claim 17.

19. A method for removing solid contaminants from a solid suspension or solid body, The steps include: introducing the solid suspension or solid suspension into the pressure separation system according to claim 17; rotating the rotor relative to the pressure screen cylinder; and collecting acceptable solid suspensions from the plurality of openings of the pressure screen cylinder. Upon contact between the solid suspension or solid suspension and the pressure screen cylinder, at least a portion of the solid suspension or solid suspension passes through the plurality of openings. The rotation of the rotor generates pressure pulses in the plurality of metal elongates that push away solid impurities and fibers entangled on the inner surface of the pressure screen cylinder. A method comprising: the forward blades moving solid contaminants and fibers inward and generating a flow field that prevents the solid contaminants and fibers from accumulating on the leading edges of the plurality of blades and the leading edges of the plurality of metal strips.

20. A method for removing solid contaminants from a solid suspension or solid body, A step of bringing the solid suspension or solid suspension into contact with a pressure screen cylinder having a cylindrical wall, wherein the cylindrical wall has an inner surface, an outer surface, and a plurality of openings penetrating from the inner surface to the outer surface, and at least a portion of the solid suspension or solid suspension passes through the plurality of openings upon contact with the pressure screen cylinder; A step of rotating a rotor disposed within the pressure screen cylinder, wherein the rotor comprises a cylindrical hub, a plurality of metal elongates radially separated outward from the hub, and a plurality of blades connecting the plurality of metal elongates to the hub, each of the metal elongates being radially separated from the inner surface of the cylindrical wall, and each of the blades being a forward blade having a forward edge, the rotation of the rotor causing the plurality of metal elongates to generate pressure pulses that push away solid contaminants and fibers entangled in the inner surface of the pressure screen cylinder, the forward blades moving the solid contaminants and fibers inward, and generating a flow field (represented by streamlines) that prevents the solid contaminants and fibers from accumulating on the forward edges of the plurality of blades and the forward edges of the plurality of metal elongates, The steps include: collecting acceptable solid suspensions from the plurality of openings of the pressure screen cylinder; A method that includes this.

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