Vibrating material screen and using method thereof

Abstract

Embodiments of the present disclosure relate to screens (110) and vibratory particle sieves (100) comprising those screens (110) wherein the screens (110) comprise: a screen frame comprising a pair of opposing transverse edges (119) and a pair of opposing longitudinal edges (117) wherein the pair of opposing transverse edges (119) and the pair of opposing longitudinal edges (117) define a horizontal plane; a plurality of wires (125) extending horizontally between the pair of opposing longitudinal edges, where the wires (125) comprise a contoured vertical profile with respect to the horizontal plane, and where adjacent wires (111, 112) have different contoured vertical profiles.

Description

[0001] Cross - reference to related applications

[0002] This application claims the benefit of Indian Patent Application No. 202241070555, filed on December 7, 2022, the entire disclosure of which is hereby incorporated by reference. Technical field

[0003] Embodiments of the present disclosure generally relate to vibratory material screens and methods of using the same. More specifically, embodiments of the present disclosure relate to an apparatus for a vibratory material screen for providing improved material separation, the apparatus including a screen with longitudinal wires Background art

[0004] In the processing of polymers, the separation of materials is an important step in ensuring high yields of components such as beads, pellets, spheroids, powders, and polyethylene in resin form. Granular sieves are one way to achieve such separation, but current vibratory screens are mainly engineered for industrial mining applications where longitudinal and transverse wires are welded to a frame. This design often results in screen clogging due to smaller material separation (such as in the aforementioned polymer applications). Accordingly, there is a continuing need for a screen for use in vibratory granular sieves that achieves a higher component separation yield without causing screen clogging. Summary of the invention

[0005] Embodiments of the present disclosure address these needs by utilizing a screen that includes multiple wires, where the screen has a wavy vertical profile. The screen may also be considered to have a wavy out - of - phase (WOOP) profile that applies a rolling motion to the particles being sorted such that the particles can re - orient themselves to allow them to pass through the screen.

[0006] According to at least one aspect of the present disclosure, a screen frame includes a pair of opposing lateral edges and a pair of opposing longitudinal edges, where the pair of opposing lateral edges and the pair of opposing longitudinal edges define a horizontal plane and multiple wires horizontally extending between the pair of opposing longitudinal edges, where the wires include a wavy vertical profile relative to the horizontal plane, and where adjacent wires have different wavy vertical profiles.

[0007] According to one or more other aspects, a vibratory granular screen may include a screen frame having a pair of opposing lateral edges and a pair of opposing longitudinal edges, where the pair of opposing lateral edges and the pair of opposing longitudinal define a horizontal plane and multiple wires horizontally extending between the pair of opposing longitudinal edges, where the wires include a wavy vertical profile relative to the horizontal plane, and where adjacent wires have different wavy vertical profiles.

[0008] According to one or more other aspects, a method of filtering out unacceptable material from a particulate mixture using a vibratory particle sieve, the vibratory particle sieve may include a screen frame having a pair of opposing lateral edges and a pair of opposing longitudinal edges, wherein the pair of opposing lateral edges and the pair of opposing longitudinal edges define a horizontal plane and a plurality of wires extending horizontally between the pair of opposing longitudinal edges, wherein the wires include a wavy vertical profile relative to the horizontal plane, and wherein adjacent wires have different wavy vertical profiles.

[0009] Additional features and advantages of the present disclosure will be set forth in the detailed description which follows, and in part will be apparent from the description, or may be learned by practice of the embodiments described herein, including the detailed description which follows, the claims, as well as the drawings.

[0010] It should be understood that both the foregoing general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and characteristics of the claimed subject matter. The drawings are included to provide a further understanding of the various embodiments, and the drawings are incorporated in and constitute a part of this specification. The drawings illustrate the various embodiments described herein and, together with the description, explain the principles and operation of the claimed subject matter. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The embodiments set forth in the drawings are illustrative and exemplary in nature and are not intended to limit the subject matter defined by the claims. The following detailed description of the illustrative embodiments can be understood when read in conjunction with the following drawings, in which like reference numerals indicate like structures and in which:

[0012] Figure 1 A schematic side view depicting two wires within a vibratory particle sieve having a WOOP profile according to one or more embodiments described in the present disclosure;

[0013] Figure 2 A schematic top view depicting two wires within a WOOP screen according to one or more embodiments described in the present disclosure;

[0014] Figure 3 A generalized isometric view of a vibratory particle sieve having a WOOP screen according to one or more embodiments described in the present disclosure

[0015] Figure 4 A generalized schematic view of the arrangement of a plurality of wires within a WOOP screen according to one or more embodiments described in the present disclosure;

[0016] Figure 5A diagram depicting various general shapes of polyethylene particles to be sorted by a vibratory particle sieve according to one or more embodiments described in the present disclosure;

[0017] Figure 6A A finite element analysis (FEA) model depicting the arrangement of polyethylene particles to be sorted by a cross-wire vibratory particle sieve;

[0018] Figure 6B An FEA model depicting a plurality of polyethylene particles after 1 second of vibration time of a cross-wire vibratory particle sieve;

[0019] Figure 7A A finite element analysis (FEA) model depicting the arrangement of polyethylene particles to be sorted by a unidirectional vibratory particle sieve;

[0020] Figure 7B An FEA model depicting a plurality of polyethylene particles after 1 second of vibration time of a unidirectional vibratory particle sieve;

[0021] Figure 7B Shows aspects of the subject matter according to one embodiment;

[0022] Figure 8 An FEA model depicting the arrangement of polyethylene particles to be sorted by a unidirectional vibratory particle sieve;

[0023] Figure 9 A top view of an FEA model depicting a plurality of polyethylene particles after 1 second of vibration time of a unidirectional vibratory particle sieve;

[0024] Figure 10A A top view of an FEA model depicting a plurality of polyethylene particles after 1 second of vibration time of a WOOP vibratory particle sieve;

[0025] Figure 10B An isometric view of an FEA model depicting a plurality of polyethylene particles after 1 second of vibration time of a WOOP vibratory particle sieve. Detailed Description

[0026] The present disclosure relates to apparatuses and methods for separating non-conforming particles from a desired product (e.g., such as polyethylene). According to at least one aspect of the present disclosure, a screen frame includes a pair of opposing lateral edges and a pair of opposing longitudinal edges, wherein the pair of opposing lateral edges and the pair of opposing longitudinal edges define a horizontal plane and a plurality of wires horizontally extending between the pair of opposing longitudinal edges, wherein the wires include a wavy vertical profile relative to the horizontal plane, and wherein adjacent wires have different wavy vertical profiles.

[0027] The devices and methods of the present disclosure enable the selection of polyolefin particles from polyethylene or polypropylene by filtering out non-conforming particles from a particulate mixture using a vibratory particle sieve, where the non-conforming material is the larger particles blocked by the screen. Additionally, the vibratory particle sieve may include a housing that includes at least one receiving bin and at least one reject bin, where the receiving bin is oriented to receive particles passing through the screen and the reject bin is oriented to receive particles filtered out by the screen.

[0028] As used in the present disclosure, "heterophase" means that adjacent wires have different curvatures in the vertical direction.

[0029] As used in the present disclosure, "blockage" refers to the clogging of the screen of a vibratory sieve. Screen blockage occurs when the screen pores become blocked or clogged by the material being screened. Once particles become trapped or accumulate on the screen surface, this prevents the screen openings from allowing the material to pass through or severely limits the passage of finer powders.

[0030] The term "polymer" refers to a polymeric compound prepared by polymerizing the same type or different types of monomers. Thus, the general term polymer encompasses the term "homopolymer", which generally refers to a polymer prepared from only one type of monomer, and "copolymer", which refers to a polymer prepared from two or more different monomers. The term "interpolymer" as used herein refers to a polymer prepared by polymerizing at least two different types of monomers. Thus, the general term interpolymer includes copolymers or polymers prepared from more than two different types of monomers, such as terpolymers.

[0031] "Polyethylene" or "ethylene-based polymer" shall mean a polymer containing greater than 50 mole % of units derived from ethylene monomers. This includes ethylene-based homopolymers or copolymers (meaning units derived from two or more comonomers). Common forms of ethylene-based polymers known in the art include, but are not limited to: low density polyethylene (LDPE); linear low density polyethylene (LLDPE); ultra low density polyethylene (ULDPE); very low density polyethylene (VLDPE); single-site catalyzed linear low density polyethylene, including both linear low density resins and substantially linear low density resins (m-LLDPE); medium density polyethylene (MDPE); and high density polyethylene (HDPE).

[0032] As used in the present disclosure, "non-conforming" means particles that do not meet the required specifications. In some cases, "non-conforming" may refer to particles having one or more dimensions greater than the product specifications.

[0033] As used in the present disclosure, "crossed wires" refers to a conventional screen design for a mesh. The mesh includes longitudinal and transverse wires that may be evenly spaced such that an area is open to allow material to drop through. The mesh is oscillated to screen the incoming material. As the material is conveyed along the inclined mesh surface, pieces of material smaller than the openings drop through, while material larger than the openings is directed to an oversize chute at the end of the device.

[0034] As used in the present disclosure, "unidirectional" refers to a screen design consisting of unidirectional wires. That is, the screen includes straight longitudinal wires. The screen does not include any transverse crossed wires and there are no undulations in the wires. The mesh is oscillated to screen the incoming material. As the material is conveyed along the inclined mesh surface, pieces of material smaller than the space between the longitudinal wires drop through, while material larger than the openings is directed to an oversize chute at the end of the device.

[0035] Now referring Figure 1 to an embodiment, a side view of two wires within a WOOP screen 110 is schematically depicted. A first wire 111 is shown adjacent to a second wire 112. Both the first wire 111 and the second wire 112 have an amplitude with an absolute value of H and a period of 2A. In some embodiments, the first wire 111 and the second wire 112 may be a pair of wavy out-of-phase wires that repeat up to and including multiple wires 125 within the WOOP screen 110 such that each wire among the multiple wires has an amplitude with an absolute value of H and a period of 2A. In this embodiment, the vertical wavy profile of the WOOP screen 110 causes adjacent wires among the multiple wires 125 to have a sinusoidal profile that is out of phase with respect to each other. In other embodiments, it is contemplated that adjacent wires among the multiple wires 125 may have inconsistent and random corresponding profiles. That is, the multiple wires 125 may include wires that do not have an ordered sinusoidal profile with respect to the profiles of other wires.

[0036] The WOOP screen 110 may have an amplitude with an absolute value between 5 mm and 10 mm. For example, referring Figure 1 to, the value of the amplitude (H) may be between 6 mm and 10 mm, between 7 mm and 10 mm, between 8 mm and 10 mm, or even between 9 mm and 10 mm. The WOOP screen 110 may also have a period between 100 mm and 300 mm. For example, still referring Figure 1 to, the value of the period (2A) may be between 125 mm and 300 mm, between 150 mm and 300 mm, between 175 mm and 300 mm, between 200 mm and 300 mm, between 225 mm and 300 mm, between 250 mm and 300 mm, or even between 275 mm and 300 mm.

[0037] Referring now to Figure 2 an embodiment of, a top view of a first wire 111 and a second wire 112 is schematically shown within a WOOP screen 110. The first wire 111 and the second wire 112 are spaced apart by a distance D. In this embodiment, the first wire 111 and the second wire 112 can be a pair of wavy out-of-phase wires that repeat up to and including multiple wires 125 within the WOOP screen 110 such that there is a horizontal spacing of distance D between each of the multiple wires. It is contemplated that in other embodiments, the horizontal spacing between each of the multiple wires 125 can be non-uniform and random and that varying distances are contemplated.

[0038] Referring now to Figure 3 an embodiment of, the arrangement of wires within the WOOP screen 110 is schematically shown. In this embodiment, the multiple wires 125 can have a undulating vertical profile extending along their length and an amplitude (not shown) with an absolute value of H. In this embodiment, each wire interleaves the undulating pattern at a period of 2A (not shown), as Figure 4 depicted. A variety of materials are considered suitable for the WOOP screen 110 and the components therein. For example, the multiple wires 125 can be stainless steel. By way of example and not limitation, the multiple wires 125 can be 304 stainless steel.

[0039] Referring now to Figure 4 , a vibratory particle screening system 100 including the above-described wavy out-of-phase (WOOP) screen 110 is schematically depicted. The WOOP screen includes a screen frame that includes a pair of opposing lateral edges 119 having a width W and a pair of opposing longitudinal edges 117 having a length L, wherein the pair of opposing lateral edges 119 and the pair of opposing longitudinal edges 117 define a horizontal plane. The WOOP screen 110 includes multiple wires 125 extending horizontally between the pair of opposing longitudinal edges 117, wherein the multiple wires 125 include a wavy vertical profile relative to the horizontal plane and wherein adjacent wires have different wavy vertical profiles.

[0040] The WOOP screen 110 can be agitated by a swing actuator (not depicted) such that the WOOP screen 110 vibrates. In some embodiments, the WOOP screen can be oriented at an angle theta (θ). The WOOP screen 110 can be oriented at an angle theta (θ) such that the WOOP screen 110 has a top 107 and a bottom 108. The vibratory particle screening system 100 is housed within a housing 105 for the WOOP screen 110 and other components such as a swing actuator (not depicted). By way of example and not limitation, the vibratory particle screening system 100 can include a commercially available housing 105 such as Model SGX48-144D-3 particle sieve.

[0041] The housing 105 also includes an acceptance bin 120 and a rejection bin 130. Acceptable or good-quality particles can fall into the entire area below the screen to the acceptance area 120, while the particles that are not filtered and reach the end of the screen fall into the rejection area 130. The particles that block the screen do not fall into either area. It is possible that good or acceptable particles do not find an opening in the screen and, due to the high speed, they fall into the rejection area 130, thus reducing the production capacity of the machine. If a large area of the screen is blocked, the production capacity of the screen is significantly reduced.

[0042] Embodiment

[0043] The various aspects of the present disclosure will be further illustrated by the following examples. The examples are illustrative in nature and should not be construed as limiting the subject matter of the present disclosure.

[0044] Comparative Example 1 and Comparative Example 2

[0045] In Comparative Example 1, finite element analysis (FEA) was used to evaluate the blocking and rejection of good polyethylene particles by a conventional cross-wire screen design. Figure 6A Comparative Example 1 is depicted before the particles acquire an initial velocity due to gravity and vibration begins. Figure 6B Comparative Example 1 is depicted at a time equal to 1.4 seconds, where various polyethylene particles have been blocked, accepted, or rejected.

[0046] In Comparative Example 2, FEA was used to evaluate the blocking and rejection of good polyethylene particles by a unidirectional mesh screen design. Figure 7A Comparative Example 2 is depicted before the particles acquire an initial velocity due to gravity and vibration begins. Figure 7B Comparative Example 2 is depicted at a time equal to 1.16 seconds, where various polyethylene particles have been blocked, accepted, or rejected.

[0047] Several types of commercial FEA software are available for performing such analyses. The results listed in the present disclosure were obtained using as an advanced general-purpose multi-physics simulation software. The FEA combines a 3D mesh model of the screen, the frame supporting the screen, the container enclosing the screen, and the particles being screened. The scope of the FEA model herein is limited to studying the effect of the screen geometry on the filtration performance, which allows for simplification in terms of structural connections.

[0048] The FEA model for each particle screen design incorporates many variables, including an actual size screen model of 4.6 m x 1.2 m. The wire mesh details of the cross wires are analyzed in 3D with a wire diameter of 6 mm. In addition, the screen vibration including amplitude and frequency and the screen angle are controlled. Gravity is considered. The FEA model also takes into account the friction between polyethylene particles and the friction between polyethylene particles and the vibrating screen. The thickness and modulus of polyethylene particles at high temperatures are also considered.

[0049] The FEA model for Comparative Example 1 and Comparative Example 2 utilizes the following material properties for the polyethylene particles: a density of 1.0E-09 ton / mm 3 , an elastic modulus of 2500 MPa, a yield stress of 80 MPa, and a Poisson's ratio of 0.3. The polyethylene particles are modeled as 1-mm thick shell elements. The material model (*MAT_PIECEWISE_LINEAR_PLASTICITY) is used to define the elastic-plastic behavior of the PE particles. The screen made of steel wire is modeled with solid elements with a typical wire diameter of 6 mm. The average element size is 1 mm. The linear elastic material model (*MAT_ELASTIC) is used for the typical elastic properties of the screen and steel. The frame supporting the screen is modeled with shell elements. The frame is rigidly fixed and the material model (*MAT_RIGID) is used for the frame. Similarly, the container is also rigidly fixed and the material model (*MAT_RIGID) is used.

[0050] The particles are dropped onto the screen at one end at a higher height. All polyethylene particles are given a certain initial velocity to incorporate the effect of dropping. The screen is tilted at an angle that allows the particles to slide downward under gravity while falling through the openings. In the model, the screen is kept horizontal (e.g., parallel to the X direction). As seen in Figure 4 , the effect of the screen angle is introduced by providing appropriate gravity components to the polyethylene particles in both the horizontal (X) and vertical (Y) directions. The typical screen tilt is 30° relative to the horizontal direction (the ground). The *LOAD_GRAVITY_PART_SET card in is used to apply gravity in both the X and Y directions to the set of polyethylene components.

[0051] In addition to the acceleration due to gravity, The *INITIAL_VELOCITY card in [description] provides an initial velocity for the polyethylene particles. The initial velocity provided to the polyethylene shell particles is 400 mm / s in the X direction. The actual velocity of the PE particles in production can be much higher and is not limited by this disclosure. No initial velocity in the Y direction is provided for the shell particles. Due to the vertical component of gravitational acceleration, a vertically downward velocity is obtained through the shell particles. Although the body of the material is thin (1 mm thick), due to the thick particles, blockage of the screen usually occurs.

[0052] The screen is supported on the frame by: using the *CONTACT_AUTOMATIC_SURFACE_TO_SURFACE_SMOOTH_ID to define the contact between them. By using the card *BOUNDARY_PRESCRIBED_MOTION_SET_ID to stretch each steel wire, the screen is also kept under tension. A 10 mm stretch is applied to each wire in the horizontal direction. This prevents excessive swaying of the wire when the particles impact the wire. By using the card *BOUNDARY_SPC_SET to prevent other degrees of freedom, the screen edges are also constrained to move only in the horizontal (X-Z) plane.

[0053] The polyethylene thin shell particles are positioned on a platform before they are pushed onto the screen. The platform is modeled with the shell element and a rigid fixed material is assigned to the platform. The *CONTACT_AUTOMATIC_SURFACE_TO_SURFACE_SMOOTH_ID card is used to define the contact between the screen wires, the container, and the platform with the PE particles. The *CONTACT_AUTOMATIC_SINGLE_SURFACE_SMOOTH_ID card is used to define the contact between the PE particles themselves. A static coefficient of friction (COF) of 0.2 and a dynamic coefficient of friction of 0.1 are defined in the contact.

[0054] The vibration of the screen can be modeled using the *BOUNDARY_PRESCRIBED_MOTION_SET_ID card associated with the cyclic amplitude curve. Additionally, the frequency of the vibration can be changed by using different amplitude curves. However, the results presented in all cases do not identify the effect of the screen geometry alone on the screening efficiency in combination with the effect of the screen vibration. The polyethylene particles landing on the screen are at a high temperature. Using COF = 1.0, the viscous behavior of the polyethylene particles due to the high temperature can be combined. To identify the effect of the screen geometry on the screening efficiency, the viscous behavior of the PE particles is not incorporated into the contact definition.

[0055] The polyethylene housing particles take about five seconds for all particles to reach the end of the screen. Due to the large size of the model, the calculation time for each run is typically about 75 hours with 8 SMP threads (8 CPUs).

[0056] For performance evaluation, various thin particle shapes and sizes were considered. Table 1 below lists the various shapes and sizes of polyethylene particles, each particle having a thickness of 1 mm. Now referring to Figure 5 , a general arrangement of various polyethylene particles 200 is schematically shown. The various polyethylene particles 200 include square polyethylene particles 210, rectangular polyethylene particles 220, larger rectangular polyethylene particles 250, wedge-shaped polyethylene particles 240, smaller wedge-shaped polyethylene particles 230, and long stripes 260.

[0057] Particle Size (mm) PE1 (Square) 20x 20 PE2 (Rectangle) 40x 20 PE3 (Rectangle) 40x 40 PE4 (Wedge) 40x 20x 37 PE4 (Wedge) 40x 16x 25 Long stripe 5x 100

[0058] Table 1

[0059] Example 1

[0060] In Example 1, FEA was used to evaluate the blocking and rejection of good polyethylene particles of the WOOP screen design in comparison with the cross-wire screen of Comparative Example 1 and the one-way screen of Comparative Example 2. The particle size was the same as those used in Comparative Example 1 and Comparative Example 2. Table 1 above lists the various shapes and sizes of polyethylene particles, each particle having a thickness of 1 mm. Figure 5 The general shapes of various polyethylene particles are depicted, where the 2D examples of the polyethylene particles listed in Table 1 can be seen. Figure 1 An embodiment of Example 1 applicable within the WOOP screen system 110 is depicted.

[0061] Except for changing the screen geometry, the FEA model for Example 1 utilized the same parameter data as Comparative Example 1 and Comparative Example 2.

[0062] Comparison of Comparative Example 1 and Comparative Example 2 with Example 1

[0063] Now, the tendency of blocking and the rejection rate of the polyethylene particles in the case of polyethylene particles of various sizes for Comparative Example 1 and Comparative Example 2 and Example 1 will be compared. Table 2 below shows the number of polyethylene particles accepted and the number of polyethylene particles rejected for each iteration run by the FEA model for the cross-wire screen, the one-way screen, and the WOOP screen.

[0064]

[0065] Table 2

[0066] As seen in Table 2 above, for a total of 81 example particles, after all iterations of running the FEA model, the cross-wire mesh system of Comparative Example 1 has an acceptance rate of 5%. For a total of 81 example particles, after all iterations of running the FEA model, the unidirectional mesh system of Comparative Example 2 has an acceptance rate of 85.2%. However, the WOOP mesh system of Example 1 shows an acceptance rate of 88.9% for the same number of particles of the same shape as both the cross-wire mesh system and the unidirectional mesh system.

[0067] In addition, the cross-wire mesh of Comparative Example 1 shows blockage, where 15 out of 81 particles block the mesh. Neither the unidirectional mesh system nor the WOOP mesh system experiences any blockage.

[0068] Comparative Example 3

[0069] In Comparative Example 3, FEA was used to evaluate the blockage and rejection of good polyethylene particles for a unidirectional mesh screen design.

[0070] In Figure 8 a general view of a unidirectional mesh system 300 including a unidirectional mesh 310 is schematically depicted. The unidirectional mesh 310 includes a mesh frame that includes a pair of opposite transverse edges 319 and a pair of opposite longitudinal edges 317, where the pair of opposite transverse edges 319 and the pair of opposite longitudinal edges 317 define a horizontal plane. The unidirectional mesh 310 includes a plurality of wires 325 extending horizontally between the pair of opposite longitudinal edges 317, where the wires 325 include straight wires (e.g., there is no curvature in the vertical direction). Also depicted are various polyethylene particles 200 at a time equal to zero. Referring Figure 9 to a top view of the unidirectional mesh of

[0071] the various polyethylene particles 200 are depicted at a time equal to 1.62 seconds at a point further down along the opposite longitudinal edges 317. In this example, there is a first wire 301 and a second wire 302, and the particle 309 is blocked between them. The particle has a size twice that of Comparative Example 1 and Comparative Example 2 and a thickness of 1 mm. The cross-wire mesh screen design was evaluated, but no polyethylene particle could successfully pass through the cross-wire design with a 1-mm thickness (e.g., 0% acceptance rate).

[0072] The FEA model for Comparative Example 3 utilized the same parameter data as Comparative Example 2, except for a variety of thin polyethylene particles. Table 3 below lists the various shapes and sizes of the polyethylene particles, each particle having a thickness of 1 mm. Figure 5Depicts the general shape of various polyethylene particles, where 2D embodiments of the polyethylene particles listed in Table 3 can be seen. Figure 8 Depicts the blockages that occur for various polyethylene particles.

[0073] Particle Size (mm) PE1 (Square) 40x 40 PE2 (Rectangle) 80x 40 PE3 (Rectangle) 80x 80 PE4 (Wedge) 80x 40x 74 PE4 (Wedge) 80x 32x 50 Long stripe 10x 200

[0074] Table 3

[0075] Example 2

[0076] In Example 2, FEA was used to evaluate the blockage and rejection of good polyethylene particles of the WOOP screen design in comparison with the unidirectional screen of Comparative Example 3. The particle has a size twice that of Comparative Example 1 and Comparative Example 2 and a thickness of 1 mm.

[0077] The FEA model for Example 2 utilized the same parametric data as Example 1, except for multiple thin polyethylene particles. Table 2 above lists the various shapes and sizes of the polyethylene particles, each with a thickness of 1 mm. Figure 5 Depicts the general shape of various polyethylene particles, where 2D embodiments of the polyethylene particles listed in Table 2 can be seen. Figure 1 Depicts an embodiment of Example 2 applicable within the WOOP screen system 110.

[0078] Comparison of Comparative Example 3 with Example 2

[0079] Now, the tendency of blockage to occur and the rejection rate of the polyethylene particles in the case of Comparative Example 3 and Example 2 for polyethylene particles of various sizes will be compared. Table 4 below shows the number of polyethylene particles accepted and the number of polyethylene particles rejected for each iteration run by the FEA model for both the unidirectional screen system and the WOOP screen system.

[0080]

[0081] Table 4

[0082] As can be seen in Table 4 above, for a total of 72 example particles, after all iterations of running the FEA model, the unidirectional screen system of Comparative Example 3 has an acceptance rate of 31.3%. However, the WOOP screen system of Example 2 shows an acceptance rate of 54.2% for the same number of particles of the same shape. Neither the unidirectional screen system nor the WOOP screen system experienced any blockage.

[0083] Comparative Example 4

[0084] In another case of Comparative Example 4, polyethylene particles with a thickness of 30 mm were analyzed in a one-way screen design. Figure 9 Fig. shows the one-way screen system 300 as viewed from above after 1.62 seconds. Blockages can be seen in the one-way screen system 300 with various polyethylene particles 200. For example, between the first wire 301 and the second wire 302, the particles 309 are blocked.

[0085] This FEA model for Comparative Example 4 utilized the same parameter data as Comparative Examples 2 and 3, except for the multiple thin polyethylene particles. This FEA model for Comparative Example 4 utilized polyethylene particles with a thickness of 30 mm, and solid elements were used instead of shell elements to model the shell elements and the particles with a thickness of 30 mm. Additionally, these polyethylene particles were set with a very small vertical downward velocity (e.g., 10 mm / s) and no initial horizontal velocity. This was done to avoid the tendency of the solid particles to rebound and fly around when the solid particles hit the steel wires. The solid particles still flying around were contained within the machine space by the container walls. Additionally, no platform was used to position the solid polyethylene particles; the solid polyethylene particles were directly positioned on the screen.

[0086] Example 3

[0087] As in Comparative Example 4, Example 3 analyzed polyethylene particles with a thickness of 30 mm. This example utilized the WOOP screen system. Figure 10A Fig. shows the one-way screen system 300 as viewed from above after 1.62 seconds. As Figure 10A depicted, compared with Figure 9 Comparative Example 3 therein, fewer polyethylene particles were blocked. Figure 10B Fig. shows the blockages that can be seen within multiple wires 125 with a wavy profile. For example, between the first wire 102 and the second wire 103, the particles 109 are blocked.

[0088] This FEA model for Example 3 utilized the same parameter data as Comparative Example 4, except for the change in the screen geometry. Table 5 below lists the various shapes and sizes of the polyethylene particles, each particle having a thickness of 30 mm. Figure 1 Fig. depicts an embodiment of Example 3 applicable within the WOOP screen system 110.

[0089] Comparison between Comparative Example 4 and Example 3

[0090] Now, a comparison will be made between Comparative Example 4 and Example 3 in terms of both the tendency of blockage occurring in the case of polyethylene particles of various sizes and the rejection rate of the polyethylene particles. Table 5 below shows, for both the unidirectional screen system and the WOOP screen system, the number of polyethylene particles accepted and the number of polyethylene particles rejected for each iteration run by the FEA model.

[0091]

[0092] Table 5

[0093] As can be seen in Table 5 above, for a total of 89 example particles, after all iterations of running the FEA model, the unidirectional screen system of Comparative Example 4 has an acceptance rate of 51.7%. The WOOP screen system of Example 3 shows an acceptance rate of 52.8% in the case of the same number of particles of the same shape. The unidirectional screen system of Comparative Example 4 experienced blockage, with 11 particles clogging the screen. The WOOP screen system of Example 3 also experienced blockage, with 9 particles clogging the screen.

[0094] Analysis of the geometry of the WOOP screen

[0095] The additional geometry of the WOOP screen and various polyethylene particles were analyzed. Table 6 below illustrates various geometries by indicating values of the amplitude with absolute value H and period 2A. Figure 1 Embodiments applicable to these examples within the WOOP screen system 110 are depicted.

[0096] Geometric structure H value A value 1 7mm 100mm 2 5mm 100mm 3 10mm 100mm 4 7mm 50mm 5 7mm 150mm

[0097] Table 6

[0098] The influence of the WOOP screen wire geometry on the acceptance efficiency for polyethylene particles with a thickness of 1 mm can be seen from Table 7 below. The range of acceptance efficiency for the WOOP screen system shown in Table 7 is from 49.4% to 62.6%, while the unidirectional screen system of Comparative Example 3 has an acceptance efficiency of 31.3%. No blockage occurred in either system.

[0099]

[0100] Table 7

[0101] Continue the analysis of the various geometries of the WOOP screen system with polyethylene particles having a thickness of 30 mm in Table 8 below. The range of acceptance efficiency for the WOOP screen system shown in Table 8 is from 48.3% to 53.9%, while the one-way screen system of Comparative Example 4 has an acceptance efficiency of 51.7%. In the case of the 30 mm thickness of the polyethylene particles, blockage occurs in the range of 9 to 11 particles out of a total of 89 particles. In Comparative Example 4, blockage occurred for 11 particles out of 89 particles.

[0102]

[0103] Table 8

[0104] It should be noted that the terms "substantially" and "about" may be used herein to represent the degree of inherent uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. These terms are also used herein to represent the degree to which a quantitative representation may differ from the stated reference without causing a fundamental change in the basic function of the subject matter being discussed.

[0105] It should be noted that one or more of the appended claims utilize the term "wherein" as a transitional phrase. For the purpose of defining the present technology, it should be noted that this term is introduced in the claims as an open transitional phrase that is used to introduce a recitation of a series of characteristics of a structure and should be interpreted in a manner similar to the more commonly used open preamble term "comprising".

[0106] Directional terms used herein - such as up, down, right, left, front, back, top, bottom - are made only with reference to the drawings as drawn and are not intended to imply absolute orientation unless otherwise specified.

[0107] Unless otherwise explicitly stated, no method listed herein is ever intended to be understood as requiring that its steps be performed in a particular order, nor any device specific orientation. Thus, in the case where a method claim does not actually recite the order in which its steps are to be followed, or any apparatus or assembly claim does not actually recite the order or orientation of the individual components, or where the claims or the specification do not otherwise specifically state that the steps are limited to a particular order, or do not recite a particular order or orientation of the components of the apparatus or assembly, no order or orientation is ever intended to be inferred in any respect. This applies to any possible non-expressive basis for interpretation, including: logical matters regarding the arrangement of steps, operational sequences, component orders, or component orientations; the ordinary meaning derived from grammatical organization or punctuation; and the number or type of embodiments described in the specification.

[0108] As used herein, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, unless the context clearly dictates otherwise, reference to "a" component includes aspects having two or more of this component.

[0109] It should be understood that any two quantitative values assigned to a characteristic can form a range of that characteristic, and all combinations of ranges formed by all of the stated quantitative values of a given characteristic are contemplated in the present disclosure.

[0110] It will be apparent to those skilled in the art that various modifications can be made to the described embodiments without departing from the spirit and scope of the claimed subject matter. Accordingly, this specification is intended to cover modifications and variations of the described embodiments as long as they come within the scope of the appended claims and their equivalents.

Claims

1. A sieve, the sieve comprising: A sieve frame, the sieve frame including a pair of opposite transverse edges and a pair of opposite longitudinal edges, wherein the pair of opposite transverse edges and the pair of opposite longitudinal edges define a horizontal plane; A plurality of wires, the plurality of wires extending horizontally between the pair of opposite longitudinal edges, wherein the wires include a wavy vertical profile relative to the horizontal plane, and wherein adjacent wires have different wavy vertical profiles.

2. The sieve according to claim 1, wherein the sieve does not include cross wires extending horizontally between the pair of opposite transverse edges.

3. The sieve according to any one of claims 1 to 2, wherein the plurality of wires comprises stainless steel.

4. The sieve according to any one of claims 1 to 3, wherein the horizontal spacing between adjacent wires is uniform.

5. The sieve according to any one of claims 1 to 4, wherein the wavy vertical profile includes a sinusoidal profile, and wherein adjacent wires are out of phase.

6. A vibrating particle sieve, the vibrating particle sieve comprising the sieve according to any one of claims 1 to 5.

7. The vibrating particle sieve according to claim 6, wherein the sieve is oriented at an angle.

8. The vibrating particle sieve according to claim 6 or claim 7, wherein the vibrating particle sieve includes a housing, the housing including at least one receiving bin and at least one reject bin, wherein the receiving bin is oriented to receive particles passing through the sieve, and the reject bin is oriented to receive particles filtered out by the sieve.

9. A method of filtering out non-conforming material from a particle mixture using the vibrating particle sieve according to any one of claims 6 to 8, wherein the non-conforming material is larger particles blocked by the sieve.

10. The method according to claim 9, wherein the particle mixture comprises polyolefin particles selected from polyethylene or polypropylene.

Images