BACKGROUND
Field
The present specification generally relates to pulp processing units for processing fibers, such as wood fibers, and, in particular, to bedplates for pulp processing units.
Technical Background
In the paper industry, processes for making paper include production of pulp, which is a solid suspension of fibers, such as cellulose fibers or other fibers. Depending on the source of the fibers, the pulp can include various concentrations and sizes of pulp fibers and solid contaminants such as wood fragments, fiber bundles, metal pieces, hardened adhesive, or other contaminants. Increasing use of recycled paper as a source of the fibers may increase the presence of hardened adhesives, metal fragments, and wood fragments in the pulp. Pulp production often includes processing the pulp in a pulp processing unit, such as but not limited to pulpers, detrashers, or other specialty pulp processing equipment. During pulp processing, a pulp source is combined with water in the pulp processing unit, which may operate to hydrate and classify the pulp fibers, remove at least a portion of solid contaminants from the pulp slurry, or combinations of these.
SUMMARY
During operation of a pulp processing unit (e.g., pulpers, detrashers, or other specialty pulp processing equipment) having a conventional bedplate and a rotor, the filtering and/or separation of larger contaminants by the conventional bedplate is accomplished via the openings having constant size and shape. During operation, the conventional bedplate is stationary, and the rotor rotates in close proximity to the conventional bedplate around their mutual center axis. The rotor creates both positive and negative pressure pulses as-well-as swirls the fiber slurry past the openings in the bedplate. The openings in the bedplate control the flow of the pulp slurry between the pulper vessel and the extraction chamber disposed below the bedplate.
The constant size and shape of the openings in the conventional bedplate is a disadvantage since, while the openings are the same size and shape, the flow conditions in the vicinity of each of the individual openings varies considerably over the surface of the conventional bedplate. For instance, the fluid pressures around the rotor vane of the rotor change depending on the radial distance from the center axis of the rotor, which in turn change the fluid velocities through the bedplate holes, as will be discussed herein. Additionally, the flow conditions are further influenced by the proximity of the openings in the bedplate to wear strips, which may be coupled to the upper axial surface of the bedplate. Not taking this variability in the flow conditions into account when designing the openings of the bedplate can limit the performance of the conventional bedplate in terms of throughflow, backflow, and contaminant removal.
Accordingly, an ongoing need exists for bedplates that can account for different flow conditions at different positions on the surface of the bedplate. The present disclosure is directed to a bedplate having openings that vary in size, shape, orientation, or combinations of these based on the position of the openings on the bedplate. The openings through the bedplate may vary in size, shape, orientation, or combinations of these depending on the position of the opening relative to the wear strips, the radial position of the opening relative to the center of the bedplate, or a combination of both. The varying size, shape, and/or orientation of the openings in the bedplate refer to the openings in the working zone of the bedplate, which is the zone over which the rotor passes. Varying the size, shape, and/or orientation of the openings in the bedplate may enable the size, shape, and/or orientation of the openings to be designed based on the local flow conditions at the upper axial surface of the bedplate. These local flow conditions can vary considerably based on the radial distance from the center of the bedplate and/or the position of the openings relative to the wear strips. Tailoring the size, shape, and/or orientation of the openings of the bedplate to the flow conditions can improve the throughflow, backflow, and solid contaminate removal performance of each individual opening, which can improve the performance and efficiency of the bedplate overall.
According to aspects of the present disclosure, a bedplate for a pulp processing unit, the bedplate comprising a plate having an upper axial surface, a lower axial surface, and plurality of openings extending through the plate from the upper axial surface to the lower axial surface. Each of the plurality of openings may have a shape, a size, and an angle, wherein the shape is the cross-sectional shape in a plane parallel to a center axis of the bedplate, the size is equal to the largest cross-sectional dimension, and the angle is an angle formed between a centerline of each of the plurality of openings and an axial line parallel to a center axis of the bedplate. The shape, the size, the orientation of the shape, the angle, or any combinations thereof of the plurality of openings may vary depending on a location of the opening on the bedplate.
According to other aspects of the present disclosure, a pulp processing unit for processing a pulp slurry may include the bedplate of any of the aspects disclosed herein. The pulp processing unit may further comprise a vessel and a rotor. The bedplate may be arranged with the upper axial surface facing towards the rotor.
It is to 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 character of the claimed subject matter.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings are included to provide a further understanding of the various embodiments, and are incorporated into and constitute a part of this specification. The drawings illustrate the various embodiments described herein, and together with the description serve to explain the principles and operations of the claimed subject matter.
FIG. 1 schematically depicts a front perspective view in partial cross-section of a pulp processing unit comprising a pulper for processing wood fibers, according to embodiments shown and described herein;
FIG. 2 schematically depicts a front cross-sectional view of the pulper rotor of the pulper of FIG. 1, according to embodiments shown and described herein;
FIG. 3 schematically depicts a top view of a conventional bedplate according to the prior art;
FIG. 4 schematically depicts a cross-sectional view of the conventional bedplate of FIG. 3, according to the prior art;
FIG. 5 schematically depicts modeling of fluid velocities for a rotor vane of the pulper rotor of FIG. 2 passing over a bedplate comprising a plurality of equally sized openings, according to embodiments shown and described herein;
FIG. 6 depicts modeling transient (e.g., time dependent) computational fluid dynamics (CFD) of fluid pressures in the vicinity of a wear strip on a flat plate as a rotor vane of the pulper rotor of FIG. 2 passes over the flat plate, according to embodiments shown and described herein;
FIG. 7 schematically depicts a rotor vane at a first position on the high pressure side relative to a wear strip attached to a flat plate, according to embodiments shown and described herein;
FIG. 8 schematically depicts the rotor vane of FIG. 7 at a second position relative to the wear strip on the flat plate where the second position corresponds to a relatively lower pressure contour in FIG. 9 at a point on the low pressure side of the wear strip, according to embodiments shown and described herein;
FIG. 9 graphically depicts fluid pressure (y-axis) as a function of time (x-axis) on the high pressure side of a wear strip and the low pressure side of a wear strip, according to embodiments shown and described herein;
FIG. 10 schematically depicts a top view of a bedplate having a size of openings that changes from a high pressure side of a wear strip to a low pressure side of an adjacent wear strip, according to embodiments shown and described herein;
FIG. 11 schematically depicts a side cross-sectional view of a portion of the bedplate of FIG. 10, according to embodiments shown and described herein;
FIG. 12 schematically depicts a top view of a bedplate without wear strips and having openings with sizes that change in the angular direction, according to embodiments shown and described herein;
FIG. 13 schematically depicts a top view of a bedplate having openings in which the size of the openings changes with radial distance from a center of the bedplate, according to embodiments shown and described herein;
FIG. 14 schematically depicts a top view of a bedplate without wear strips and having openings that change in size with radial distance from the center of the bedplate, according to embodiments shown and described herein;
FIG. 15 schematically depicts a top view of a bedplate in which the openings change in size based on the radial position relative to the center of the bedplate and in the angular direction relative to the wear strips, according to embodiments shown and described herein;
FIG. 16 schematically depicts a top view of a bedplate having openings that change in shape with radial distance from the center of the bedplate, according to embodiments shown and described herein;
FIG. 17 schematically depicts a top view of a bedplate having openings that change in shape based on an angular position of the openings relative to the wear strips, according to embodiments shown and described herein;
FIG. 18 schematically depicts a top view of a bedplate having openings that have the same shape and same size but change in orientation with changing radial distance from the center of the bedplate, according to embodiments shown and described herein;
FIG. 19 schematically depicts a side cross-sectional view of a portion of a bedplate having openings extending through wear strips of the bedplate, according to embodiments shown and described herein;
FIG. 20 schematically depicts a side cross-sectional view of a portion of a bedplate having openings that are angled relative to a line normal to an upper axial surface of the bedplate, where the openings are angled in an angular direction towards a low pressure side of a wear strip, accordingly to embodiments shown and described herein;
FIG. 21 schematically depicts a side cross-sectional view of a portion of a bedplate having openings that are angled in an angular direction towards a high pressure side of a wear strip (i.e., opposite angular direction from FIG. 20), accordingly to embodiments shown and described herein;
FIG. 22 schematically depicts a side cross-sectional view of a portion of a bedplate having openings that are angled relative to a line normal to an upper axial surface of the bedplate, wherein the openings are angled in an increasing radial direction, accordingly to embodiments shown and described herein;
FIG. 23 schematically depicts a side cross-sectional view of a portion of a bedplate having openings that are angled in a decreasing radial direction (i.e., opposite radial direction from FIG. 22), accordingly to embodiments shown and described herein;
FIG. 24 schematically depicts a side cross-sectional view of a portion of a bedplate having openings that are angled and have sizes that change in the angular direction, accordingly to embodiments shown and described herein;
FIG. 25 schematically depicts a side cross-sectional view of a portion of a bedplate having openings that are angled and have sizes that change in the radial direction, accordingly to embodiments shown and described herein;
FIG. 26 schematically depicts a side cross-sectional view of a portion of a bedplate having openings that change in angle relative to a line normal to an upper axial surface of the bedplate, according to embodiments shown and described herein;
FIG. 27 schematically depicts a side cross-sectional view of another embodiment of a portion of a bedplate having openings that change in angle relative to a line normal to an upper axial surface of the bedplate, according to embodiments shown and described herein;
FIG. 28 schematically depicts a side cross-sectional view of a portion of a bedplate having openings that change in angle and size with respect to the angular direction, according to embodiments shown and described herein;
FIG. 29 schematically depicts a side cross-sectional view of a portion of a bedplate having openings in which a magnitude of an angle of the openings increases with increasing radial direction, according to embodiments shown and described herein;
FIG. 30 schematically depicts a side cross-sectional view of a portion of a bedplate having openings in which a magnitude of an angle of the openings increases with decreasing radial direction, according to embodiments shown and described herein;
FIG. 31 schematically depicts a side cross-sectional view of a portion of a bedplate having openings in which a chamfer at both ends of the openings change with changing position on the bedplate, according to embodiments shown and described herein;
FIG. 32 schematically depicts a top view of a bedplate having openings that are slots and the size of the slots changes with changing radial position on the bedplate, according to embodiments shown and described herein;
FIG. 33 schematically depicts a top view of a bedplate having openings that are slots and the size of the slots changes with radial and/or angular position on the bedplate, according to embodiments shown and described herein; and
FIG. 34 schematically depicts a top view of a bedplate having openings that are slots, where an orientation of the slots changes with changing position on the bedplate, according to embodiments shown and described herein.
DETAILED DESCRIPTION
Reference will now be made in detail to embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. Referring to FIGS. 1 and 2, a bedplate 120 for a pulp processing unit 100 may include a flat plate 122 comprising an upper axial surface 124, a lower axial surface 126, and plurality of openings 130 extending through the flat plate 122 from the upper axial surface 124 to the lower axial surface 126. The bedplate 120 may further include a plurality of wear strips 140 extending outward from the upper axial surface 124 of the bedplate 120. Each of the plurality of openings 130 may have a shape, a size, and an orientation, wherein the shape is the cross-sectional shape and the size is equal to the largest cross-sectional dimension. The shape, the size, the orientation, or combinations thereof of each of the plurality of openings 130 may vary depending on a location of the opening 130 on the bedplate 120.
Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order, nor that specific orientations be required with any apparatus. Accordingly, where a method claim does not actually recite an order to be followed by its steps, or that any apparatus claim does not actually recite an order or orientation to individual components, or it is not otherwise specifically stated in the claims or description that the steps are to be limited to a specific order, or that a specific order or orientation to components of an apparatus is not recited, it is in no way intended that an order or orientation be inferred, in any respect. This holds for any possible non-express basis for interpretation, including: matters of logic with respect to arrangement of steps, operational flow, order of components, or orientation of components; plain meaning derived from grammatical organization or punctuation, and; the number or type of embodiments described in the specification.
Directional terms as used herein—for example up, down, right, left, front, back, top, bottom—are made only with reference to the figures as drawn and the coordinate axis provided therewith and are not intended to imply absolute orientation.
As used herein, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a” component includes aspects having two or more such components, unless the context clearly indicates otherwise.
As used herein, the terms “longitudinal” and “axial” refer to an orientation or direction generally parallel with the center axis A of the pulper rotor.
As used herein, the term “radial” refers to a direction along any radial line extending outward from the center axis A of the pulper rotor of from a center of the bedplate.
As used herein, the terms “forward” and “aft” refer to location or position on an object relative to a direction of movement of that object, with “forward” being towards the direction of movement and “aft” being away from the direction of movement. The term “forward edge” of a rotor vane disclosed herein refers to the edge of the rotor vane facing toward the direction of rotation of the pulper rotor and the term “aft edge” of the rotor vane refers to the edge of the rotor vane facing in a direction opposite from the direction of rotation of the pulper rotor.
As used herein, the term “inboard” refers to a radial direction towards the center axis A of the pulper rotor and the term “outboard” refers to a direction radially outward away from the center axis A of the pulper rotor.
Referring now to FIG. 1, one embodiment of a pulp processing unit 100 for processing paper pulp is schematically depicted. The pulp processing unit 100 is depicted in FIG. 1 as a pulper and embodiments disclosed herein are described in the context of a pulper. However, embodiments of the bedplate disclosed herein may be utilized in other types of pulp processing units 100, such as but not limited to detrashers or other specialized pulp processing equipment, with similar expectations of success. The pulp processing unit 100 may comprise a vessel 102 and a rotor assembly 104 disposed in a bottom of the vessel 102. The rotor assembly 104 may comprise a rotor 105 comprising a plurality of rotor vanes 106 extending radially outward from a center of the rotor 105. The rotor assembly 104 may further include a rotor cap 109. The rotor assembly 104 may further comprise a bedplate 120 disposed vertically below the rotor vane 106 (i.e., in the −Z direction of the coordinate axis of FIG. 1).
Referring now to FIG. 2, the rotor assembly 104 may further include a rotor shaft 110. The rotor shaft 110 may be rigidly coupled to the rotor 105 on one end and coupled to a rotor drive (not shown) on the other end. The rotor drive may rotate the rotor shaft 110, which may, in turn, rotate the rotor 106. The rotor cap 109 may be coupled to a top of the rotor 105 and may protect the bearings of the rotor assembly 104 from intrusion of liquids and fibers from the pulp slurry in the vessel 102 during operation. In embodiments, each of the rotor vanes 106 may have a rotor wear strip 141 extending vertically downward (i.e., in the −Z direction of the coordinate axis in FIG. 2) from a bottom surface of each of the rotor vanes 106. In embodiments, the rotor vanes 106 may not include rotor wear strips 141.
Referring again to FIG. 2, the bedplate 120 may be disposed vertically below (i.e., in the −Z direction of the coordinate axis in FIG. 2) the rotor 105 and may be spaced apart from the rotor 105. The bedplate 120 may be stationary and decoupled from the rotor 105 so that the rotor 105 can rotate relative to the bedplate 120 during operation. The bedplate 120 may comprise a flat plate 122 having an upper axial surface 124 and a lower axial surface 126. The upper axial surface 124 of the bedplate 120 may be spaced apart from the bottom surface of the rotor 105 to form a gap G between the bedplate 120 and the rotor 105. In embodiments, the bedplate 120 may include a plurality of wear strips 140 extending generally outward from the center of the bedplate towards the outer edge of the bedplate 120. In embodiments, the bedplate 120 does not include the wear strips.
Referring to FIGS. 1 and 2, the bedplate 120 may include a plurality of openings 130. The openings 130 may extend axially through the flat plate 122 from the upper axial surface 124 to the lower axial surface 126. The axial direction refers to the direction parallel to the center axis A of the rotor assembly 104 (i.e., a direction parallel to the +/−Z direction of the coordinate axis in FIGS. 1 and 2).
Referring again to FIGS. 1 and 2, the pulp processing unit 100 may further include an extraction chamber 112 disposed vertically below (i.e., in the −Z direction of the coordinate axis of FIG. 2) the bedplate 120 so that the bedplate 120 is disposed between the rotor 105 and the extraction chamber 112. The extraction chamber 112 may be an annular chamber in fluid communication with the openings 130 in the bedplate 120. The extraction chamber 112 may be in fluid communication with an accepted fiber outlet 114. During operation of the pulp processing unit 100, accepted fibers processed in the gap G between the rotor vanes 106 and the bedplate 120 pass through the openings 130 in the bedplate 120 into the extraction chamber 112. The accepted fibers pass through the extraction chamber 112 to the accepted fiber outlet 114. The accepted fibers may then be passed out of the pulp processing unit 100 to one or more downstream operations for further processing upstream of a paper making process.
Referring again to FIG. 1, the pulp processing unit 100 may further include a reject outlet 116, which may be in fluid communication with the internal volume of the vessel 102. The reject outlet 116 provides an outlet for solid contaminants and oversized pulp fibers to be removed from the pulp processing unit 100.
Referring again to FIGS. 1 and 2, during operation of the pulp processing unit 100, a pulp source (e.g., wood pulp, recycled paper, or other source of fibers) and water may be introduced to the vessel 102 from the top 103 of the vessel 102. The rotor 105 is rotated relative to the bedplate 120. Rotation of the rotor 105 may operate to agitate the contents of the vessel 102 to produce a pulp slurry. During rotation of the rotor 105, a portion of the pulp slurry may penetrate into the gap G between the stationary bedplate 120 and the rotating rotor 105. Shear forces in the gap G between the rotor 105 and the bedplate 120 may process the fibers, such as by separating agglomerates of fibers into individual fibers, breaking up fibers, or other processing. A portion of the acceptable fibers and water then pass through the openings 130 in the bedplate 120 into the extraction chamber 112. The accepted pulp slurry travels through the extraction chamber 112 to the accepted fiber outlet 114. Centrifugal forces from the rotating rotor 105 may cause heavier fibers, fiber agglomerates, debris, etc. to travel radially outward out of the gap G between the bedplate 120 and the rotor 105 and back into the vessel 102 or to the rejected fiber outlet 116.
Referring now to FIG. 3, a top view of a conventional bedplate 20 is schematically depicted. The conventional bedplate 20 generally comprises a plurality of wear strips 40 coupled to the upper axial surface 24 of the bedplate 20. The conventional bedplate 20 has a working zone 36 and a non-working zone 38. The working zone 36 is the area of the conventional bedplate 20 over which the rotor 105 rotates during operation of the pulp processing unit 100. Since the diameter of the conventional bedplate 20 is typically larger than the outer diameter of the rotor 105, the conventional bedplate 20 can include the non-working zone 38, which is the peripheral area of the conventional bedplate 20 over which the rotor vanes 106 of the rotor 105 do not pass. The non-working zone 38 is the annular area disposed between the working zone 136 and an outer circumference 29 of the conventional bedplate 20.
Referring to FIGS. 3 and 4, conventional bedplates 20 have openings 30 extending through the thickness of the conventional bedplate 20 from the upper axial surface 24 to the lower axial surface 26. For conventional bedplates 20, the openings 30 in the working zone 36 of the bedplate are generally uniform, having the same shape, the same size, and the same orientation. The same size means that the openings 30 all have the same cross-sectional area. The openings 30 can be round, polygonal, or irregular shaped. Generally, the openings 30 in the working zone 36 of conventional bedplates 20 all have the same shape, size, and orientation.
During operation of a pulper having a conventional bedplate 20, the filtering and/or separation of larger contaminants by the conventional bedplate 20 is accomplished via the openings 30 having constant size and shape. During operation, the conventional bedplate 20 is stationary, and the rotor rotates in close proximity to the conventional bedplate 20 around their mutual center axis A. Otherwise, this process would stop almost immediately due to a blinding of the openings 30 by the fiber slurry and contaminants. The rotor creates both positive and negative pressure pulses as-well-as swirls the fiber slurry past the openings parallel to the upper axial surface 24 of the conventional bedplate 20. The positive and negative pressure pulses are significantly affected by the local linear speed of the rotor 105. The local linear speed of each rotor vane 106 and a point on the rotor vane 106 increases as the point is moved radially outward from the center axis A, such as from an inboard end to an outboard end of the rotor vane 106. The magnitudes of the positive and negative pressure pulses are roughly proportional to the square of the radius. According to Equation 1 (EQU. 1), the linear velocity (V) at any point on the rotor vane 106 is equal to the rotational velocity (ω) times the radius (r).
The fluid pressure (P) is roughly proportional to the square of the linear velocity according to Equation 2 (EQU. 2).
In EQU. 2, P is the magnitude of the fluid pressure, V is the linear speed at a point on the rotor vane 106, r is the radius at the point on the rotor vane 106, ω is the rotational velocity in radians per time, and ρ is the density of the fiber slurry.
Referring now to FIG. 5, CFD modeling of fluid velocity during passage of the rotor vane 106 over the upper axial surface 24 of the conventional bedplate 20 of FIGS. 3 and 4 having openings 30 with constant shape and size. The direction of movement of the rotor vane 106 is indicated by arrow 118. FIG. 5 demonstrates the fluid flow of the pulp slurry down through the openings 30 in the conventional bedplate 20 into the extraction chamber 112 below the conventional bedplate 20 proximate the leading edge 107 of the rotor vane 106. The pulp slurry can flow back up through the openings 30 in the conventional bedplate 20 from the extraction chamber 112 back in the vessel 102 (backflow). The term “throughflow” refers to flow of the pulp slurry through the openings from the vessel to the extraction chamber. The term “backflow” refers to the flow of the pulp slurry through the openings from the extraction chamber back up into the vessel. As shown in FIG. 5, the openings 30 in the conventional bedplate 20 control the flow of the pulp slurry between the vessel 102 and the extraction chamber 112. FIG. 5 also shows that the flow conditions in the vicinity of the openings 30 varies widely during passage of the rotor vanes 106 over the upper axial surface 124 of the conventional bedplate 20.
The constant size, shape, and orientation of the openings 30 in the conventional bedplate 20 are a disadvantage since, while the openings are the same size and shape, the flow conditions in the vicinity of each of the individual openings 30 varies considerably over the surface of the conventional bedplate 20. Not taking this variability in the flow conditions into account when designing the openings 30 of the conventional bedplate 20 can limit the performance of the conventional bedplate 20 in terms of throughflow, backflow, and contaminant removal.
For instance, as previously discussed, the fluid pressures at the leading edge 107 of the rotor vane 106 change depending on the radial distance from the center axis A of the rotor 105, which in turn changes the fluid velocities. As previously discussed in EQU. 1 and EQU. 2, the fluid pressure is proportional to the square of the linear velocity of the rotor vane 106, which depends on the radial distance (radius r) from the center of the rotor 105. Thus, as the radius increases, the magnitudes of the fluid pressure increase and the fluid velocities (both throughflow and backflow) through the holes increases. With constant openings 30, the performance of the conventional bedplate 20 for classifying pulp fibers and removing solid contaminants will vary depending on the radius from the center, leading to inefficiencies.
Additionally, the flow conditions are further influenced by the proximity of the opening in the bedplate to the wear strips. Referring now to FIG. 6, the fluid pressures generated by the rotor vane 106 passing over a wear strip 140 on the surface of a plate 160 is modeled. The direction of movement of the rotor vane 106 is indicated by arrow 118 in FIG. 6. The wear strip 140 has a high pressure side 142 and a low pressure side 144. During passage of the rotor vane 106 over the wear strip 140, the rotor vane 106 encounters the high pressure side 142 of the wear strip 140 first and then the low pressure side 144. As shown in FIG. 6, the fluid pressure at the upper surface of the plate 160 is greatest at the high pressure side 142 of the wear strip and much lower at the low pressure side 144 of the wear strip 140.
Due to the dependence of the fluid velocities through the openings in the bedplate on the fluid pressure, the greater pressures at the high pressure side of the wear strip increases the throughflow velocities of pulp slurry passing through the openings in the bedplate into the extraction chamber. Likewise, the lower pressures at the low pressure side of the wear strip may decrease the throughflow velocities or cause the pulp slurry to backflow back up through the openings from the extraction chamber to the vessel. When FIG. 6 is compared to the fluid velocities in FIG. 5, it is apparent that the presence of the wear strip greatly influences the flow patterns of the pulp slurry as the rotor vane 106 passes over the wear strip 140. In FIG. 5, the flow velocities through the openings 30 in the conventional bedplate 20 are greatest at the leading edge 107 of the rotor vane 106. However, as shown in FIG. 6, as the rotor vane 106 passes the wear strip 140, the leading edge 107 passes over the low pressure side 144 of the wear strip 140, which causes a decrease of the fluid pressure at the leading edge 107. Thus, as the rotor vane 107 passes over the wear strip 140, the greatest pressure is actually nearer to the trailing edge 108 of the rotor vane 106 instead of the leading edge 107, which changes the normal flow patterns created by the rotation of the rotor vanes 106.
Referring to FIGS. 7-9, sequential passage of the rotor vanes 106 over the wear strip 140 attached to the flat plate 140 is modeled. In FIG. 7, the rotor vane 106 is positioned at the high pressure side 142 of the wear strip 140, and in FIG. 8, the rotor vane 106 has mostly passed the wear strip. The pressure at point 162 is modeled as a function of time as a rotor vane 106 moves towards the wear strip (as in FIG. 7), over the wear strip, and then past the wear strip (as shown in FIG. 8). Referring now to FIG. 9, the pressure (y-axis) as a function of time (x-axis) is graphically depicted for the high pressure side (point 162 in FIGS. 8 and 9) of a wear strip (reference 802) and the low pressure side of a wear strip (reference 804). As shown in FIG. 9, the pressure reaches a maximum for the high pressure side of the wear strip, which corresponds to the position of the a rotor vane 106 in FIG. 7. FIG. 9 demonstrates how much the flow conditions can change as the rotor vanes 106 pass over the wear strips 140 on the bedplate. Conventional bedplates 20 with openings 30 of constant size, shape, and/or orientation do not account for the differences in flow conditions resulting from the wear strips 140 and, therefore, introduce additional inefficiencies of the pulp fiber classification and/or solid contaminant removal performance of the conventional bedplate 20 in the vicinity of the wear strips 140.
Referring now to FIG. 10, the present disclosure is directed to a bedplate 120 having openings 130 that vary in size, shape, orientation, or combinations thereof based on the position of the openings 130 on the bedplate 120. The openings 130 through the bedplate 120 may vary in size, shape, orientation, or combinations thereof depending on the position of the opening 130 relative to the wear strips 140, the radial position of the opening 130 relative to the center 128 of the bedplate 120, or a combination of both. The varying size, shape, and/or orientation of the openings 130 in the bedplate 120 refers to the openings 130 in the working zone 136 of the bedplate 120 and is not intended herein to include any openings in the non-working zone 138 of the bedplate 120, which is the part of the bedplate 120 extending radially outward beyond the outboard end of the rotor vanes 106.
Varying the size, shape, orientation, or combinations thereof of the openings 130 in the bedplate 120 may allow the size, shape, and/or orientation of the openings 130 to be designed based on the local flow conditions at the upper axial surface 124 of the bedplate 120. As previously discussed, these local flow conditions can vary considerably based on the radial distance from the center 128 of the bedplate 120 or the position relative to the wear strips 140, when present. Tailoring the size, shape, and/or orientation of the openings 130 of the bedplate 120 to the local flow conditions at each position can improve the throughflow, backflow, and solid contaminate removal performance of each individual opening 130, which can improve the performance and efficiency of the bedplate 120 overall.
The shape of the openings 130 refers to the cross-sectional shape of the openings, where the cross-sectional shape is the shape of the opening 130 in a plane perpendicular to an axial centerline of the opening 130. The size of the openings refers to the largest cross-sectional dimension of the cross-sectional shape of the openings 130. For instance, for cylindrical shaped openings 130 with circular cross-sectional shapes, the size of the openings refers to the diameter of the circular cross-section of the openings 130. For openings 130 having a polygon cross-sectional shape, the size of the opening 130 refers to the largest corner-to-corner distance of the cross-sectional shape. For irregular cross-sectional shapes, the size of the openings 130 refers to the largest cross-sectional dimension of the opening 130. For openings 130 that do not have a circular cross-sectional shape, the orientation of the openings 130 refers to the rotational position of the cross-sectional shape relative to the axial centerline of the opening 130. Variation of the sizes, shapes, and/or orientation of the openings 130 discussed herein refers to the sizes, shapes, and/or orientation of the openings 130 in the working zone 136 of the bedplate 120 and is not intended to refer to any difference in size or shape of openings in the non-working zone 138 of the bedplate 120. In FIGS. 10-25, the relative sizes of the openings 130 are not to scale and are exaggerated for purposes of illustration.
Referring again to FIG. 10, the bedplate 120 may include one or a plurality of wear strips 140 coupled to the upper axial surface 124 of the bedplate 120. The wear strips 140 extend axially towards the rotor 105. The bedplate 120 may include 2, 3, 4, 5, 6, or more than 6 wear strips 140. Each of the wear strips 140 may extend generally radially outward (i.e., in the +r direction of the coordinate axis in FIG. 11) from the center 128 of the bedplate 120 toward the outer circumference 129. In embodiments, the wear strips 140 may extend directly in the radial direction straight outward between the center 128 and the outer circumference 129 of the bedplate 120. In embodiments, the wear strips 140 may be angled or curved relative to the radial direction. The wear strips 140 may be angled or curved in the direction of rotation of the rotor 105 (FIG. 2) or counter to the direction of rotation of the rotor 105. In embodiments, the wear strips 140 may be straight and angled relative to the radial direction.
The wear strips 140 have the high pressure side 142 and the low pressure side 144. The low pressure side 144 of the wear strip 140 is the side of the wear strip 140 facing in the direction of rotation 118 of the rotor. The high pressure side 142 of the wear strip is the side of the wear strip 140 opposite from the low pressure side 144. The rotor vanes 106 (FIGS. 1 and 2) encounter the high pressure side 142 before passing over the low pressure side 144.
Referring again to FIG. 10, in embodiments, the openings 130 of the bedplate 120 in the working zone 136 may vary in size based on the position of the opening 130 relative to the wear strips 140. In embodiments, the openings 130 proximate to the high pressure side 142 of the wear strips 140 may be smaller in size. Due to the increased pressure and fluid velocity at the high pressure side 142 of the wear strips 140, decreasing the size of the openings in the vicinity of the high pressure side 142 may reduce the volume flow rate of the pulp slurry through the openings 130 proximate the high pressure side 142 to account for the greater pressure and fluid velocity. Similarly, in embodiments, the openings 130 may be larger in size proximate to the low pressure side 144 of the wear strips 140. Due to the lower pressure, the velocity of fluid flow through the openings 130 at the low pressure side 144 is less. Thus, the increase in size of the openings 130 proximate the low pressure side 144 may increase the volume of the pulp slurry passing back through the openings 130 to compensate for the decreased pressure and resulting fluid velocity. Decreasing the size of the openings 130 at the high pressure side 142 and increasing the size of the openings at the low pressure side 144 of the wear strips 140 may increase the consistency and uniformity of performance of the bedplate 120 relative to the angular (theta, Θ) direction, thereby increasing the efficiency of the bedplate 120 overall.
In embodiments, the size of the openings 130 may gradually increase in size from a smallest size at the high pressure side 142 of one wear strip 140 to a largest size at the low pressure side 144 of an adjacent wear strip 140, which is adjacent in the angular direction opposite from the direction of rotation of the rotor (i.e., in the −Θ (−theta) direction of the coordinate axis in FIG. 10). In FIG. 10, the +Θ direction is the same as the direction of rotation 118 of the rotor. In embodiments, at each radial distance from the center 128 of the bedplate 120, the size of each of the plurality of openings 130 varies relative to an angular position (i.e., position in the +/−Θ direction of the coordinate axis in FIG. 10) of each of the plurality of openings 130.
Referring now to FIG. 11, a cross-sectional view of the bedplate 120 of FIG. 10 between two wear strips 140 in the working zone 136 is schematically depicted. In embodiments, the size of each of the plurality of openings 130 may vary relative to a proximity of each of the plurality of openings 130 to the high pressure side 142 of the wear strips 140. As shown in FIG. 11, proximate the high pressure side 142 of the wear strip 140, the openings 130 may have a smaller size, and the size of the openings 130 may increase as the distance from the high pressure side 142 of the wear strip 140 increases in the angular direction (e.g., moving in the −Θ direction of the coordinate axis in FIG. 11). Referring to FIG. 11, the openings 130 in the bedplate 120 may include a first opening 150 and a second opening 152, where the first opening 150 and the second opening 152 are at the same radial distance from the center 128 of the bedplate 120. The first opening 150 may have a first angular position relative to a reference wear strip 140 and the second opening 152 may have a second angular position relative to the reference wear strip 140. The first opening 150 may have a size that is different from a size of the second opening 152. The absolute value of the difference in size between the first opening 150 and the second opening 152 may be greater than the manufacturing tolerance of the openings 130, such as greater than or equal to 5%, greater than or equal to 10%, greater than or equal to 15%, greater than or equal to 20%, or even greater than or equal to 25% of the size of the smallest of the first opening 150 or second opening 152.
Referring again to FIG. 11, the wear strips 140 have the high pressure side 142 and the low pressure side 144, and the bedplate 120 may comprise the first opening 150 proximate the high pressure side 142 of one of the wear strips 140 and the second opening 152 spaced farther from the high pressure side 142 in the angular direction (i.e., the −Θ direction of the coordinate axis in FIG. 11) compared to the first opening 150. In embodiments, the first opening 150 may have a size that is less than the size of the second opening 152. As shown in FIG. 11, the smaller size of the first opening 150 proximate the high pressure side 142 of the wear strip 140 may restrict flow 170 through the first opening 150 from the upper axial surface 124 to the lower axial surface 126. As shown in FIG. 11, when the rotor vane 106 is passing over the wear strip 140, the smaller size of the first opening 150 and larger size of the second opening 152 may cause restriction of the flow 170 through the first opening 150 from the upper axial surface 124 to the lower axial surface 126 and may enable back flow 172 through the second opening 152 from the lower axial surface 126 to the upper axial surface 124. Due to the higher pressures at the high pressure side 142 of the wear strip 140, the restriction of the flow 170 through the first opening 150 may improve the separation efficiency of the bedplate 120 at the high pressure side 142 of the wear strips 140.
Referring again to FIGS. 10 and 11, in embodiments, each wear strip 140 comprises the high pressure side 142 and the low pressure side 144, and at each radial distance from the center 128 of the bedplate 120, the size of each of the plurality of openings 130 increases with increasing angular distance (i.e., distance in the +/−Θ direction of the coordinate axis of FIGS. 10 and 11) from the high pressure side 142 of each wear strip 140 to the low pressure side 144 of each adjacent wear strip 140.
Referring now to FIG. 12, in embodiments, the bedplate 120 may not have wear strips extending axially from the upper axial surface 124 of the bedplate 120. In these embodiments, the bedplate 120 may have openings 130 that have a size that changes based on the angular position (i.e., position in the +/−Θ direction of the coordinate axis in FIG. 12) of the opening 130 on the bedplate 120. In embodiments, the openings 130 may have a repeating pattern of increasing or decreasing sizes of the openings 130 with respect to the angular direction.
Referring now to FIG. 13, in embodiments, the openings 130 of the bedplate 120 in the working zone 136 may have sizes that change depending on the radial position of the opening 130 relative to the center 128 of the bedplate 120. As previously discussed, the pressures and the potential for causing axial flow through the bedplate, created by the pressures increases with increasing radial distance from the center axis A of the rotor 105 (i.e., the center 128 of the bedplate 120). To compensate for the increased pressures and resulting potential with increasing radius, the openings 130 in the bedplate 120 may be larger proximate to the center 128 of the bedplate and may decrease in size with increasing radial distance from the center 128 of the bedplate 120. The size of the openings 130 at the outermost portions of the working zone 136 of the bedplate 120 may be smaller than the size of the openings 130 that are closer to the center 128 of the bedplate 120. Increasing the size of the openings 130 closer to the center 128 of the bedplate 120 and decreasing the size of the openings 130 proximate the outermost portion of the working zone 136 of the bedplate 120 may make the volume flow through the openings 130 to the extraction chamber more consistent with radial position, which may improve the efficiency of the bedplate for classifying pulp fibers and/or removing solid contaminants from the pulp slurry.
In embodiments, the size of the openings 130 may have a greatest size at a position closest to the central opening of the bedplate 120, and the size of the openings 130 may gradually decrease with increasing radial distance from the center 128 of the bedplate 120. The smallest opening size may be for openings in the working zone 136 that are the greatest radial distance from the center 128 of the bedplate 120, but still in the working zone 136. In embodiments, the bedplate 120 may comprise a first opening 154 disposed at a first radial distance from the center 128 of the bedplate 120 and a second opening 156 disposed at a second radial distance from the center 128 of the bedplate 120, where the first radial distance may be greater than the second radial distance, and the first opening 154 may have a first size that is less than a second size of the second opening 156. Referring now to FIG. 14, in embodiments, the bedplate 120 may not have any wear strips on the upper axial surface 124 of the bedplate 120, and the size of the openings 130 may change based on the radial position of the opening, such as the size of the openings 130 decreasing with increasing radial distance from the center 128 of the bedplate 120.
Referring now to FIG. 15, in embodiments, the size of the openings 130 may vary depending on the radial distance of the opening 130 from the center 128 of the bedplate 120 and on the angular position (i.e., position in the +/−Θ direction of the coordinate axis in FIGS. 11-13) of the opening 130 relative to the wear strips 140. In embodiments, the size of the openings 130 may decrease with increasing radial distance from the center 128 of the bedplate and with increasing angular distance from the high pressure side 142 of the wear strips 140. In embodiments, the largest sized openings 130 may be closest to the center 128 of the bedplate 120 and closest to the low pressure sides 144 of the wear strips 140, and the smallest sized openings 130 may be at the greatest distance from the center 128 of the bedplate 120 and closest to the high pressure side 142 of the bedplate 140.
Referring now to FIGS. 16 and 17, in embodiments, the cross-sectional shape of the openings 130 may change based on the position of the openings 130 in the working zone 136 of the bedplate 120. Referring now to FIG. 16, in embodiments, the cross-sectional shape of the openings 130 may change based on the angular position (i.e., position in the +/−Θ direction of the coordinate axis in FIG. 16) of the opening 130 relative to the high pressure side 142 of the wear strips 140. In embodiments, the openings 130 in the bedplate 120 may include a first opening and a second opening, where the first opening and the second opening are at the same radial distance from the center 128 of the bedplate 120. The first opening may have a first angular position relative to a reference wear strip 140 and the second opening may have a second angular position relative to the reference wear strip 140. The first opening may have a shape that is different from a shape of the second opening.
Referring now to FIG. 17, in embodiments, the cross-sectional shape of the openings 130 may change based on the radial distance from the center 128 of the bedplate 120. In embodiments. In embodiments, the bedplate 120 may comprise a first opening disposed at a first radial distance from the center 128 of the bedplate 120 and a second opening disposed at a second radial distance from the center 128 of the bedplate 120, where the first radial distance may be greater than the second radial distance, and the first opening may have a first shape that is different from a second shape of the second opening. In embodiments, the shape of the openings 130 may vary depending on both the radial position and the angular position of the openings 130.
Referring now to FIG. 18, in embodiments, the openings 130 may have a non-circular shape, and the orientation of the non-circular shape of the openings 130 may be modified based on the position of the opening on the bedplate 120. The orientation of the non-circular shapes of the openings 130 may be modified based on the radial distance of the opening 130 from the center 128 of the bedplate, the angular position relative to one or more wear strips 140, or both in the radial and angular direction. Changing the orientation of the shapes refers to rotating the shape about a centerline of the openings, where the centerline of the opening refers to a line passing through the geometric center of the shape of the opening 130 at the upper axial surface 124 of the bedplate 120 and the geometric center of the shape of the opening 130 at the lower axial surface 126 of the bedplate 120. For openings 130 that extend axially through the bedplate 120, the centerline may be an axial line parallel to the center axis A of the rotor 105 (FIG. 2) and passing through the geometric center of the cross-sectional shape of the opening 130. In other words, the cross-sectional shape of the openings 130 may be rotated relative to one another based on the radial and/or angular position of the openings 130 on the bedplate 120.
Referring now to FIG. 19, in embodiments, the bedplate 120 may include a plurality of wear strip openings 146. The wear strip openings 146 may be axially extending openings in the bedplate that pass through the bedplate 120 and the wear strip 140. When the bedplate 120 includes the wear strip openings 146, each of the wear strips 140 may have a width that is greater than the wear strips 140 that do not have wear strip openings 146.
Referring to FIG. 19, in embodiments, the openings 130 may extend axially through the bedplate 120 so that the centerline 180 is perpendicular to the upper axial surface 124 of the bedplate 120 and parallel to the center axis A of the rotor 105 (FIG. 2). Referring now to FIGS. 20 and 21, in embodiments, an orientation of the openings 130 relative to the axial direction (i.e., the +/−Z direction of the coordinate axis in FIGS. 20 and 21) may change based on the radial and/or angular position of the openings 130 on the bedplate 120.
Referring now to FIG. 20, in embodiments, the openings 130 may be angled relative to the axial direction (i.e., the +/−Z direction of the coordinate axis in FIG. 20). The openings 130 may have a centerline 180 that is not perpendicular to the upper axial surface 124 of the bedplate 120 such that the centerline 180 of the opening 130 forms a non-zero angle α (alpha) with an axial line 182 perpendicular to the upper axial surface 124 of the bedplate 120. In embodiments, the angle α may be less than 45 degrees, less than or equal to 40 degrees less than or equal to 35 degrees, or even less than or equal to 30 degrees. In embodiments, the angle may be from zero degrees to 45 degrees, from zero degrees to 40 degrees, from zero degrees to 35 degrees, from zero degrees to 30 degrees, from 5 degrees to 45 degrees, from 5 degrees to 40 degrees, from 5 degrees to 35 degrees, from 5 degrees to 30 degrees, from 10 degrees to 45 degrees, from 10 degrees to 40 degrees, from 10 degrees to 35 degrees, from 10 degrees to 30 degrees, from 15 degrees to 45 degrees, from 15 degrees to 40 degrees, from 15 degrees to 35 degrees, from 15 degrees to 30 degrees, from 20 degrees to 45 degrees, from 20 degrees to 40 degrees, from 20 degrees to 35 degrees, or from 20 degrees to 30 degrees.
In embodiments, all of the openings 130 may have the same angle α. Referring to FIGS. 20 and 21, the angle α of the openings 130 may slant in the angular direction (i.e., in the +/−Θ direction of the coordinate axis in FIGS. 20 and 21). In other words, in embodiments, the centerline 180 of the openings 130 may diverge from the axial line 182 perpendicular to the upper axial surface 124 of the bedplate 120 in the annular (Θ) direction. Referring to FIG. 20, in embodiments, the openings 130 may be angled towards the low pressure side 144 of the wear strips 140 such that the end of each opening 130 at the upper axial surface 124 of the bedplate 120 is closer to the low pressure side 144 of the wear strip 140 compared to the end of the opening at the lower axial surface 126 of the bedplate 120 (e.g., angled in the −Θ direction of the coordinate axis in FIG. 20). Referring to FIG. 21, in embodiments, the openings 130 may be angled towards the high pressure side 142 of the wear strips 140 such that the end of each opening 130 at the upper axial surface 124 of the bedplate 120 is closer to the high pressure side 142 of the wear strip 140 compared to the end of the opening at the lower axial surface 126 of the bedplate 120 (e.g., angled in the +Θ direction of the coordinate axis in FIG. 21).
Referring now to FIGS. 22 and 23, in embodiments, the openings 130 in the bedplate 120 may be angled (i.e., slant) in the radial direction (i.e., the +/−r direction of the coordinate axis in FIGS. 22 and 23). In embodiments, the centerline 180 each of the openings 130 may diverge from the axial line 182 perpendicular to the upper axial surface 124 of the bedplate 120 in the radial (r) direction. Referring to FIG. 22, in embodiments, the openings 130 may be angled radially outward such that the end of each opening 130 at the upper axial surface 124 of the bedplate 120 is closer to the outer circumference 129 of the bedplate 120 compared to the end of the opening 130 at the lower axial surface 126 of the bedplate 120 (e.g., angle in the +r direction of the coordinate axis in FIG. 22). Referring to FIG. 23, in embodiments, the openings 130 may be angled radially inward such that the end of each opening 130 at the upper axial surface 124 of the bedplate 120 is closer to the center axis A of the bedplate 120 compared to the end of the opening at the lower axial surface 126 of the bedplate 120 (e.g., angled in the −r direction of the coordinate axis in FIG. 23).
In FIGS. 22 and 23, the openings 130 in the working zone 136 are shown as being angled, and the outer openings 139 in the non-working zone 138 of the bedplate are shown as extending axially through the bedplate 120 (i.e., angle α=zero). It is understood that the outer openings 139 in the non-working zone 138 of the bedplate 120 may also be angled either in the angular direction (i.e., +/−Θ direction of the coordinate axis in FIGS. 22 and 23) or in the radial direction (i.e., +/−r direction of the coordinate axis in FIGS. 22 and 23).
Referring now to FIG. 24, the openings 130 may all have the same angle α, but the size of the openings 130 may change based on the angular position (i.e., position in the +/−Θ direction of the coordinate axis of FIG. 24) of the openings 130 relative to the wear strips 140. In embodiments, the openings 130 may have an angle α that is slanted toward the low pressure side 144 of the wear strips 140, and the sizes of the openings 130 may increase from a smallest size proximate the high pressure side 142 of a wear strip 140 to the low pressure side 144 of the adjacent wear strip 140. Although FIG. 24 shows the openings 130 being angled or slanted towards the low pressure side 144 of the wear strips 140, it is understood that the openings 130 may also be angled or slanted towards the high pressure side 142 of the wear strips 140.
Referring now to FIG. 25, the openings 130 may all have the same angle α, but the size of the openings 130 may change based on the radial position of the openings 130 (i.e., position in the +/−r direction of the coordinate axis in FIG. 25). In embodiments, the openings 130 may have an angle α that is slanted toward the center axis A, and the sizes of the openings 130 may increase from a smallest size proximate the non-working zone 138 of the bedplate 120 to a largest size proximate the center axis A of the bedplate 120. Although FIG. 25 shows the openings 130 being angled or slanted towards the center axis A of the bedplate 120, it is understood that the openings 130 may also be angled or slanted towards the outer circumference 129 of the bedplate 120.
In embodiments, the openings 130 may be configured so that the non-zero angle α (alpha) of the centerline 180 of the openings 130 changes based on the radial and/or angular position of the opening 130 on the bedplate 120. Referring to FIG. 26, in embodiments, the bedplate 120 may have openings 130 that are substantially axial closest to the low pressure side 144 of a wear strip 140 and openings 130 that are angled closest to the high pressure side 142 of an adjacent wear strip 140. In embodiments, the angle α (alpha) may change from the low pressure side 144 of one wear strip 140 to the high pressure side 142 of an adjacent wear strip 140, such as increasing from about zero degrees at the low pressure side 144 to an non-zero angle α (alpha) of less than 90 degrees, less than 60 degrees, less than 45 degrees, less than 30 degrees, or less than 20 degrees at the high pressure side 142 of the adjacent wear strip 140. In embodiments, the angle α of the opening closest to the low pressure side 144 of one wear strip 140 may be from zero degrees to 30 degrees, from zero degrees to 25 degrees, from zero degrees to 20 degrees, from zero degrees to 15 degrees, from zero degrees to 10 degrees, from zero degrees to 5 degrees, or any range or subrange therein, and the angle α of the openings 130 closest to the high pressure side 142 of the adjacent wear strip 140 may be from 20 degrees to 45 degrees, such as from 25 degrees to 45 degrees, from 30 degrees to 45 degrees, from 35 degrees to 45 degrees, from 40 degrees to 45 degrees, or any range or subrange therein.
Referring now to FIG. 27, in embodiments, the bedplate 120 may have openings 130 that are substantially axial closest to the high pressure side 142 of a wear strip 140 and openings 130 that are angled closest to the low pressure side 144 of an adjacent wear strip 140. In embodiments, the angle α (alpha) may increase from about zero degrees at the high pressure side 142 to a non-zero angle α (alpha) of less than 90 degrees, less than 60 degrees, less than 45 degrees, less than 30 degrees, or less than 20 degrees at the low pressure side 144 of the adjacent wear strip 140. In embodiments, the angle α of the opening closest to the high pressure side 142 of one wear strip 140 may be from zero degrees to 30 degrees, from zero degrees to 25 degrees, from zero degrees to 20 degrees, from zero degrees to 15 degrees, from zero degrees to 10 degrees, from zero degrees to 5 degrees, or any range or subrange therein, and the angle α of the openings 130 closest to the low pressure side 144 of the adjacent wear strip 140 may be from 20 degrees to 45 degrees, such as from 25 degrees to 45 degrees, from 30 degrees to 45 degrees, from 35 degrees to 45 degrees, from 40 degrees to 45 degrees, or any range or subrange therein.
Although shown in FIGS. 26 and 27 as being angled toward the low pressure side 144 of the wear strip 140, in embodiments, the openings 130 may be angled towards the high pressure side 142 of the wear strip. In embodiments, the openings 130 may be angled in the +Θ direction, the −Θ direction, or a combination of both, such as being angled towards the low pressure side 144 proximate to the low pressure side 144 of the wear strips 140 or angled towards the high pressure side 142 proximate to the high pressure side 142 of the wear strips 140. In embodiments, the openings 130 proximate to the low pressure side 144 may be angled toward the high pressure side 142 and openings 130 proximate to the high pressure side 142 may be angled toward the low pressure side 144.
Referring now to FIG. 28, in embodiments, the size and angle α of the openings 130 may vary with changing angular position (i.e., in the +/−Θ direction of the coordinate axis in FIG. 28) between the wear strips 140. As shown in FIG. 28, the opening 130 closest to the low pressure side 144 of the wear strip 140 may have the largest size and the smallest angle α. As the angular direction proceeds in the +Θ direction, the openings 130 may decrease in size and increase in angle α. In embodiments, both the size and the angle α may increase with increasing angular direction (i.e., +Θ direction) from the low pressure side 144 of one wear strip 140 to the high pressure side 142 of the adjacent wear strip 140. Although the angle α of the openings 130 is shown in FIG. 28 as being angled towards the low pressure side 144 of the wear strips 140, it is understood that the angle α of the openings 130 may be angled toward the high pressure side 142 of the wear strips 140.
Referring now to FIGS. 29 and 30, in embodiments, the angle α (alpha) of the openings 130 may vary based on the radial position of the openings 130 relative to the center axis A of the bedplate 120. Referring to FIG. 29, in embodiments, the openings 130 proximate the center axis A (e.g., closest to the center axis A) may have a small angle α. The angle α of the openings 130 may increase with increasing radial distance (i.e., +r direction of the coordinate axis in FIG. 29) from the center axis A of the bedplate 120. Thus, the openings 130 proximate the non-working region 138 of the bedplate 120 may have a larger angle α compared to the openings 130 closer to the center axis A. In embodiments, the angle α of the openings 130 may gradually increase in magnitude with increasing radial distance from the center axis A.
Referring now to FIG. 30, in embodiments, openings 130 proximate the center axis A (e.g., closest to the center axis A) may have a large angle α. The angle α of the openings 130 may decrease with increasing radial distance (i.e., +r direction of the coordinate axis in FIG. 30) from the center axis A of the bedplate 120. Thus, the openings 130 proximate the non-working region 138 of the bedplate 120 may have a smaller angle α compared to the openings 130 closer to the center axis A. In embodiments, the angle α of the openings 130 may gradually decrease in magnitude with increasing radial distance from the center axis A.
When the angle α of the openings 130 changes based on the radial distance from the center axis A, the openings 130 may be angled radially outward (as in FIG. 29), radially inward (as in FIG. 30), or a combination of both. In embodiments, the angle α may vary depending on radial distance of the openings 130 from the center axis A, but the openings 130 may be angled in the +/−Θ direction or any other direction. Although not shown in FIG. 29 or 30, in embodiments, both the size and the angle α of the openings 130 may vary with changing radial distance from the center axis A of the bedplate 120.
Referring now to FIG. 31, in embodiments, the contour of the openings 130 at the upper axial surface 124, the lower axial surface 126, or both may change based on the radial position, the angular position, or both of the openings 130 on the bedplate 120. As shown in FIG. 31, in embodiments, each of the openings 130 may have a chamfer 190 at the upper axial surface 124, the lower axial surface 126, or both. In embodiments, the chamfer 190 of the openings 130 may change based on the radial position, the angular position, or both of the openings 130 on the bedplate 120. As shown in FIG. 31, in embodiments, the chamfer 190 of the openings 130 may be small or nonexistent proximate the low pressure side 144 of one wear strip 140 and may increase in size as the openings 130 get farther from the low pressure side 144 and closer to the high pressure side 142 of the adjacent wear strip 140. In FIG. 31, the size of the chamfer 190 of the openings 130 increases in the +Θ direction of the coordinate axis in FIG. 31 from the low pressure side 144 of one wear strip 140 to the high pressure side 142 of the adjacent wear strip 140.
Referring now to FIGS. 32 and 33, in embodiments, the openings 130 may be shaped as slots 192 in the bedplate 120. In embodiments, the size of the slots 192 may change based on the radial position, the angular position, or both of the openings on the bedplate 120. Referring now to FIG. 32, in embodiments, the size of the slots 192 may change based on the radial distance from the center 128 of the bedplate 120. The slots 192 may have a length and a width. Changing the size of the slots 192 may include changing the length, the width, or both of the slot 192. In embodiments, the slots 192 may have a largest size at radial positions closest to the center 128 of the bedplate 120 and may have decreasing sizes with increasing radial distance from the center 128 of the bedplate 120. As previously discussed, the smaller size of the slots 192 at greater radial distance from the center 128 of the bedplate 120 may account for the greater pressures and fluid velocities created by the increasing tip speed of the rotor 105 (FIG. 2) as the radial distance increases.
Referring now to FIG. 33, in embodiments, the size of the slots 192 may change with changing angular position of the openings 130. In embodiments, the size of the slots 192 may change based on the angular position of the openings 130 relative to the wear strips 140. For instance, in embodiments, the slots 192 may have a largest size proximate to the low pressure side 144 of the wear strips 140 and a smallest size proximate to the high pressure side 142 of the wear strips 140. This may account for the difference in the fluid flow conditions and fluid pressures at the high pressure side 142 compared to the low pressure side 144, as previously discussed herein. In embodiments, the sizes of the slots 192 may increase in the angular direction from the smallest size proximate the high pressure side 142 of the wear strips 140 to the largest size proximate the low pressure side 144 of the wear strips 140.
Referring now to FIG. 34, in embodiments, the orientation of the slots 192 may be changed based on the radial position, the angular position, or both. For instance, in embodiments, the slots 192 may have a radial orientation (e.g., slot length generally aligned with the radial direction) at radial distances closest to the center 128 of the bedplate 120 and more of an angular orientation (e.g., slot length generally aligned with the angular direction (O direction) and perpendicular to the radial direction) closest to the outer radial portion of the working zone 136 of the bedplate 120. In embodiments, the slots 192 may have an angular orientation at radial distances closest to the center 128 of the bedplate 120 and radial orientations in the outer radial portions of the working zone 136 of the bedplate 120. The orientation of the slots 192 may be gradually changed with increasing radial distance from the center 128 of the bedplate 120. In embodiments, the orientation of the slots 192 may be changed based on the angular position between wear strips 140.
Referring again to FIG. 1, the present disclosure further discloses methods of processing a pulp slurry using the bedplates 120 disclosed herein. The methods may comprise introducing a pulp slurry to a pulp processing unit 100 that includes a vessel 102 and a rotor assembly 104 disposed in a bottom of the vessel 102. The rotor assembly 104 may comprise a rotor 105 and the bedplate 120 of the present disclosure, the bedplate 120 having openings 130, where the size, shape, or both of the openings 130 in the bedplate 120 are different sizes, shapes, or orientations depending on the location of the opening on the bedplate 120. The rotor assembly 104, rotor 105, and bedplate 120 may have any of the features or characteristics previously discussed herein for these features. The pulp processing unit 100 may further include the extraction chamber 112 disposed on the side of the bedplate 120 opposite from the rotor 105. The extraction chamber 112 may be in fluid communication with the accepted fiber outlet 114. The pulp processing unit 100 may further include the rejected fiber outlet 116.
The methods may include operating the pulp processing unit 100 by rotating the rotor 105 relative to the bedplate 120. Rotation of the rotor 105 relative to the bedplate 120 may cause the accepted fiber slurry to pass through the openings 130 in the bedplate 120 and into the extraction chamber 114 and may cause rejected fibers and solid contaminants to be conveyed to the rejected fiber outlet 116. The bedplate 120 having the openings 130, with these openings 130 having graduated size, shape, and/or orientation, may improve throughflow, backflow, and/or solid contaminate removal performance of each individual opening 130, which can improve the performance and efficiency of the bedplate 120 overall.
While various embodiments of the bedplate for the pulp processing units have been described herein, it should be understood that it is contemplated that each of these embodiments and techniques may be used separately or in conjunction with one or more embodiments and techniques. 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. Thus, it is intended that the specification cover the modifications and variations of the various embodiments described herein provided such modification and variations come within the scope of the appended claims and their equivalents.
Patent Application
20250137197
