Fine grinding machine grinding disc

Abstract

A refiner disc (101, 201) for use in a refiner disc (30, 30*) of a refiner (100) for refining lignocellulosic material, the refiner disc (1) having an active surface comprising a plurality of teeth (10), the teeth extending on the active surface (2) towards an outer periphery (18b) of the refiner disc, wherein at least three teeth (10) comprise an end box fluid connection (21), which is a fluid connection arranged through the teeth (10). , for connecting the last box (23a) on one side of the tooth with the last box (23a) on the other side of the tooth (10) so that the pressure between the two last boxes (23a) can be balanced via a box fluid connection (21), wherein the last box fluid connection (21) is arranged in the tooth (10) at a distance of 0.0-15.0 mm from the closest last slurry stop (11a), which extends from the tooth (10) to another adjacent tooth (10).

Description

Technical Field

[0001] The present invention relates to a refiner sheet for use in a refiner disc of a refiner for refining lignocellulosic material. More particularly, the present invention relates to a refiner sheet comprising teeth and a barrier, a refiner disc of a refiner comprising such a refiner sheet, and a refiner comprising a refiner disc equipped with a refiner sheet comprising teeth and a barrier. Background Art

[0002] For example, a commonly used refiner of lignocellulosic material comprises two relatively rotating discs between which the material is refined or defibrated. The pair of relatively rotating discs may in particular comprise a rotating disc, referred to as a rotor, and a stationary disc, referred to as a stator. Alternatively, the pair of relatively rotating discs may comprise two rotating discs rotating in opposite directions. The discs or at least one of them are usually provided with components referred to as refiner plates, the purpose of which is to obtain a more effective refinement of the material. A specific type of refiner plate is provided with sets of teeth and dams. Teeth are essentially radially extending and protruding structures which are arranged on the active surface (active surface) of the plate, i.e. the surface of the plate on which the material flows, and are mainly used to achieve an effective refinement of lignocellulosic material. Dams are also protruding structures arranged on the active surface of the refiner plate, but they are usually not arranged in a radial direction. Instead, these dams are arranged on the refiner plate such that a particular dam contacts or connects two adjacent teeth. That is, the dam is arranged so that it straddles the direction connecting two adjacent teeth. The direction may be approximately orthogonal to the teeth, but may also be arranged at an angle relative to the teeth. The specific purpose of the pulp stop is to lift the material flowing in the area between the teeth in an upward direction, towards the disk gap defined as the gap between two opposing refiner disks, for example, the disk gap between a rotor and a stator or the disk gap separating two relatively rotating disks. The material is refined or dissociated in the disk gap between the disks. In the common case where each tooth is connected to one or several pulp stops, a natural consequence of this geometry is the creation of a number of partially enclosed or defined areas between adjacent teeth. These areas are referred to as boxes in the detailed description below. The main part of the refined material will flow in these areas. A specific problem associated with refiner plates equipped with teeth and pulp stops is that, as structures protruding from the surface of the refiner plates, the teeth and pulp stops are subject to wear due to their abrasive contact with the material to be refined. As a result, the efficiency of the refiner plates will decrease over time and the refiner plates will need to be replaced in order to achieve a satisfactory quality of the refined material, for example pulp. The present invention seeks to provide a mechanism which alleviates at least some of the problems associated with the wear experienced by refiner plates provided with teeth and baffles. Summary of the invention

[0003] The object of the present invention is to improve the wear resistance of a refiner plate of a refiner caused by material flow on the refiner plate.

[0004] Another object of the present invention is to provide a refiner plate, a refiner disc comprising a refiner plate, and a refiner comprising a refiner disc, which refiner has improved robustness against wear caused by material flow on the refiner plate.

[0005] These objects are achieved by a refiner segment, a refiner disc and a refiner according to the independent claims.

[0006] According to a first aspect of the present invention, there is provided a refiner plate for use in a refiner disc of a refiner for refining lignocellulosic material. The refiner plate has an active surface defined by an inner periphery, an outer periphery, a first side edge and a second side edge of the refiner plate, wherein the active surface comprises:

[0007] - a plurality of teeth extending on the active surface towards the outer periphery of the refiner plate, thereby forming a plurality of grooves, wherein each groove is between two adjacent teeth; and

[0008] - a plurality of blade stops, wherein each blade stop extends between two adjacent blade teeth,

[0009] wherein at least some of the grooves comprise one or more pulp stops which are separated along the groove extension and whereby some of the grooves comprise one or more boxes, wherein a box is defined by two adjacent teeth and two adjacent pulp stops arranged in the same groove, wherein a last box and a last pulp stop are defined as a box and a pulp stop, respectively, for a groove which are positioned closest to the outer periphery of the refiner grinding plate compared to other possible boxes and pulp stops arranged in the same groove,

[0010] At least three of the blade teeth include a last box fluid connection, which is a fluid connection arranged through the blade tooth and is used to connect the last box on one side of the blade tooth with the last box on the other side of the blade tooth, so that the pressure between the two last boxes can be balanced via the last box fluid connection, wherein the last box fluid connection is arranged in the blade tooth, and the distance from the closest last pulp stop is between 0.0-15.0 mm, and the closest last pulp stop extends from the blade tooth to another adjacent blade tooth.

[0011] According to a second aspect of the present invention, there is provided a refiner disc comprising a refiner plate according to the first aspect.

[0012] According to a third aspect of the present invention, there is provided a refiner comprising a refiner disc according to the second aspect.

[0013] The invention provides a refiner disc and a corresponding refiner disk and a refiner which better withstand the wear caused by the abrasive contact between the slurry stop and the material flowing on the refiner disc. This in turn will extend the effective life of the refiner disc. According to the invention, by providing a last box fluid connection at at least three teeth, the pressure can be balanced between two or more adjacent last boxes, which are separated by one or more teeth including such a last box fluid connection. Thus, it is avoided that a higher pressure is generated at a specific location of the refiner disc, which would lead to uneven wear and possible leakage. Furthermore, by providing this last box fluid connection near the last slurry stop of the groove, a single high pressure in the last box of the groove can be avoided, thereby balancing the pressure between a plurality of last boxes. Because a pressure peak is provided somewhere in the last box, this is the part of the refiner disc that is most sensitive to wear. Therefore, according to the invention, the wear of the refiner disc can be more uniform, which is suitable. Furthermore, by balancing the pressure between more than one final box, the pressure in each of these final boxes will be less than the previous highest pressure, which is suitable, and this will reduce the wear of the refiner plates and extend the life of the refiner plates. Since the individual pressures in the final boxes are balanced between at least some of the final boxes, the probability that individual boxes will become targets of wear / leakage will be much lower. Further, by arranging the final box fluid connection in the cutter tooth as close as possible (i.e., a distance between 0-15 mm) to the nearest final slurry stop extending from the cutter tooth to another adjacent cutter tooth, there is very little risk that the location of the pressure peak in the final box on each side of the cutter tooth is closer to the outer periphery than the final box fluid connection. In most cases, the location of the pressure peak will be arranged between the final box fluid connection and the inner periphery of the refiner plate, which is suitable because the pressure balancing will be more effective. In contrast, if the pressure peak is located between the final box fluid connection and the outer periphery of the refiner plate, the pressure will not be balanced or at least not be balanced effectively. In this case, the pressure peak will prevent fluid balancing between the final boxes. Therefore, the location of the last box fluid connection according to the invention close to the nearest last pulp stop (hereinafter also referred to as the pressure drop line, pressure drop below) is advantageous and provides effective pressure balance and thus more uniform wear of the refiner grinding plates.

[0014] In some embodiments of the invention, the refiner plates are configured to be positioned on the refiner disc such that they cover at least a portion of the surface of the refiner disc and such that the inner periphery of the refiner plates is disposed closer to the center C of the refiner disc than the outer periphery.

[0015] In some embodiments of the invention, the refiner segments are sectors of a circle having a central opening.

[0016] In one embodiment of the invention, a number of teeth corresponding to at least half of the total number of teeth provided in the refiner plate comprises a last box fluid connection.

[0017] In one embodiment of the invention, at least every other blade tooth that is part of the last tank comprises a last tank fluid connection.

[0018] In one embodiment of the invention, at least three adjacent teeth each comprise a final tank fluid connection.

[0019] In one embodiment of the invention, the last box fluid connection has a width of 0.1-5.0 mm along the length extension of the tooth disposed therein, and a depth of 0.1-20.0 mm from the upper surface of the tooth disposed therein.

[0020] In one embodiment of the invention, at least four final barriers arranged in adjacent grooves are positioned such that they together form a continuous barrier arranged along a smooth curve.

[0021] Other advantages will be appreciated when reading the detailed description and the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a schematic diagram of a refiner in which the refiner plates according to the invention can be used.

[0023] Figure 2 is a schematic diagram of a cross section of a refiner disc arrangement, in which a refiner plate according to the invention can be used.

[0024] Figure 3 is a schematic diagram of a known refiner grinding plate viewed from above.

[0025] Figure 4 is a schematic diagram of a known refiner plate attached to a refiner disc, such as a rotor disc or a stator disc.

[0026] Figure 5 Schematic diagram of a fine grinding machine grinding plate according to an embodiment of the present invention.

[0027] Figure 6 Schematic diagram of a fine grinding machine grinding plate according to another embodiment of the present invention. DETAILED DESCRIPTION

[0028] Throughout the drawings, the same reference numerals are used for similar or corresponding elements. Generally, unless a different meaning is explicitly given and / or is implied from the context of use, all terms used herein are to be interpreted according to their ordinary meaning in the relevant technical field. Where appropriate, any feature of any embodiment disclosed herein may be applied to any other embodiment.

[0029] In order to better understand the present invention, it may be useful to first provide a brief description of a typical refiner and a brief analysis of the technical problem that the present invention aims to alleviate.

[0030] For this purpose, refer to Figure 1 , which schematically shows a refiner in which the present invention can be utilized. Figure 1 An exemplary pulp refiner 100 is schematically shown in a cross-sectional view. The arrangement is accommodated in a housing 26, which represents the housing of the refiner device and all components of the device, which (not shown) are not necessary for understanding the present invention. Examples of components not shown are an electric motor for driving, for example, a rotating shaft, a feeding mechanism for lignocellulosic material, etc. Inside a second housing 31, rotor refiner discs 30 and stator refiner discs 30* are aligned linearly along the axis. The rotor refiner discs 30 are attached to a rotating shaft 15 arranged on bearings 16. The rotating shaft 15 is connected to a not shown motor, which rotates the shaft 15 and thus the rotor refiner discs 30. The stator refiner discs 30* facing the rotor refiner discs 30 can be provided with a centrally located through hole 32, which extends between the feed channel 14 for lignocellulosic material and the refining area 19. The feeding of the material into the refining area 19 does not necessarily need to be via a through hole 32. Figure 1 and Figure 2 The centrally located through hole shown is provided, on the contrary, it is possible to have through holes distributed in another way instead of a precisely central through hole. In some embodiments, the rotor refiner disc 30 can be provided with a center plate 17, the surface of which faces the incoming flow of lignocellulosic material. The surface of the center plate 17 can be provided with a structure that guides the lignocellulosic material outward. The rotor refiner disc 30* and / or the stator refiner disc 30 are provided with refiner discs to enable the pulp to be diverted and refined. These refiner discs can be provided with blade teeth and pulp stops, which will be described in more detail below. In some refiners, there may be two rotor refiner discs instead of one rotor and one stator refiner disc, wherein the two rotor refiner discs rotate in opposite directions. The present invention can also be applied in such refiners.

[0031] During use, lignocellulosic material, such as wood chips or prepared wood, for example pulp, will be fed through the feed channel 14 by means of a feeding mechanism such as a screw feeder, not shown. The material will pass through the holes 32 in the stator refiner discs 30* and enter the area 19. The area 19 is essentially defined by the open area between the rotor 30 and the stator refiner discs 30*, and this area can be small during operation. The lignocellulosic material flowing into the area 19 will be incident on the center plate 17 on the rotor refiner discs 30. The center plate 17 serves to turn the lignocellulosic material out towards the refiner plates on the rotor and / or stator refiner discs.

[0032] To provide a more detailed description of the rotor-stator arrangement in which the present invention may be used, reference is made to Figure 2 . Figure 2 A side cross-sectional view of a rotor-stator arrangement housed in a housing 31, for example in a refiner as described above, is shown. A rotor refiner disc 30 is shown, which is arranged to rotate about a rotation axis and a stator refiner disc 30*. The rotor refiner disc 30 is provided with at least one refiner disc 1 on a surface facing the stator refiner disc 30*. The stator refiner disc 30* is provided with at least one refiner disc 1 on a surface facing the rotor refiner disc 30. These refiner discs 1, which are respectively provided on the rotor refiner disc 30 and the stator refiner disc 30*, can have an identical or different design. The refiner discs according to the invention can be provided to one or both of the rotor 30 and the stator refiner disc 30*, or in the case of two rotating discs to one or both of the two rotor refiner discs. In certain forms of refiners, the rotor and stator refiner discs can be referred to as disc holders, since one of the purposes of the refiner discs is to carry the refiner discs 1. Also in Figure 2 3 is an inlet 32 ​​for the lignocellulosic material to be refined. The inlet 32 ​​is arranged in the central region of the stator refiner disc 30*, however, as mentioned above, the central position of the inlet 32 ​​is not essential. In the central region of the rotor refiner disc, opposite the inlet 32, a center plate 17 is arranged. Figure 1 The purpose of the center plate 17 described is to distribute the material falling from the inlet 32 ​​towards the outer sections of the rotor refiner disc 30. That is, the center plate 17 serves to distribute the material towards the refiner plates 1 arranged on the rotor refiner disc 30. In examples including two rotor refiner discs rotating in opposite directions, the inlets for material feeding may be arranged differently, as is well known in the art.

[0033] The above has been combined Figure 1 and Figure 2 A general purpose refiner is described that may utilize the present invention. Figure 3A schematic diagram of an example of a refiner disc 1 is provided. The refiner disc 1 is to be provided to a refiner disc 30. This can be both a rotor refiner disc 30 and a stator refiner disc 30*, but will only be referred to as a refiner disc 30 in the following. In this particular example, the refiner disc 1 comprises a sector of a circle. There are other versions of refiner discs, but the invention is equally valid for all specific refiner disc shapes. The refiner disc 1 is provided in the shape of a disc to be attached to the refiner disc 30. The refiner disc 1 can be provided in the shape of a circle, optionally with a central area removed, for leaving room for a center plate 17 or an inlet 32 ​​as described above. The refiner disc 1 can also be provided in the shape of a sector of a circle, wherein the circle optionally has a central area removed, or the disc 1 can have the shape of another part of a circle. The refiner disc 30 can thus be provided with a number of refiner discs 1, whereby it will be completely or partially covered by the refiner discs 1. In case the refiner plate 1 forms part of a rotor refiner disc, the central region of the rotor refiner disc may comprise a centre plate 17 as described above.

[0034] Figure 3 A refiner disc 1 is shown with an inner periphery 18a and an outer periphery 18b. The inner periphery 18a is the periphery of the refiner disc 1 which is intended to be closest to the center C of the refiner disc 30 when the refiner disc 1 has been attached to the center C of the refiner disc 30. The refiner disc 1 comprises an active surface 2 provided with a plurality of teeth 10. The teeth extend on the active surface towards the outer periphery 18b of the refiner disc 1. The teeth 10 may extend substantially radially and run in an almost parallel manner along the active surface of the refiner disc, i.e. the surface facing the material flow. However, the teeth 10 may also be arranged in a direction slightly deviating from the radial extension and they may not all be as radial as in the embodiment of the present invention. Figure 3 The blade teeth 10 are shown as running parallel to each other, which is well known in the art. A plurality of paddle blocks 11 are also shown, which can be arranged substantially orthogonal to the blade teeth 10, but can also be arranged obliquely to the blade teeth 10, and wherein each paddle block 11 is connected to two blade teeth 10 in a pair of adjacent blade teeth 10. The arrangement of blade teeth 10 and paddle blocks 11 defines a defined area (section, section) surrounded by two adjacent blade teeth 10 and two paddle blocks 11, which is called a box 23.

[0035] Figure 4 When Figure 3 1 is a simplified view of a refiner plate 1 in FIG. 1 attached to a refiner disc 30 of a stator or rotor having a center C. The radial direction is shown by means of an arrow marked R. The radial direction extends from the center C of the refiner disc 30 towards the periphery of the refiner disc 30 passing the inner periphery 18a and the outer periphery 18b of the refiner plate 1 on the way.

[0036] Reference again Figure 3During use of the refiner plate 1, a major part of the lignocellulosic material will flow in the grooves 19, which are arranged between the teeth 10. As previously mentioned, when the material flows towards the outer periphery 18b of the refiner plate 1, the material will impact on the pulp barriers arranged in the grooves 19 and be lifted towards the refiner disc gap. The interaction between the flowing material and the pulp barriers 11 and the teeth 10 will cause a lot of wear on the pulp barriers 11 and the teeth 10 and may quickly damage at least part of the pulp barriers 11 and the teeth 10, thereby reducing the efficiency of the refiner plate 1. The boxes 23 may each have a separate and different pressure, which may lead to uneven wear, wherein the boxes 23 with the highest pressure will be most affected. In particular, the last boxes 23a in the radial direction R in each groove 19 may be affected by the wear, because there will be pressure peaks in these last boxes 23a. The pressure in the last box 23a of each groove 19 will have the highest pressure. However, the pressure of the last box 23a will be independent for each groove 19. The last boxes 23a with the highest individual pressure will be most affected by the wear. If even only one or some of the last boxes 23a are affected by greater wear or even become damaged, the refiner plates 1 will not function properly. Efficient and uniform refining of the lignocellulosic material will not be possible and the entire refiner plates 1 will need to be replaced.

[0037] Figure 5 Schematic diagram of a fine grinding machine grinding plate 101 according to an embodiment of the present invention. Figure 6 FIG. 2 is a schematic diagram of a fine grinding machine grinding plate 201 according to another embodiment of the present invention. Many details are similar to those already described in FIG. Figure 3 and these details are given the same figure numbers and will not be described in detail again.

[0038] refer to Figure 5 and 6 , a refiner disc 101, 201 for use in a refiner disc 30, 30* of a refiner 100 for refining lignocellulosic material is provided. The refiner disc 101, 201 has an active surface 2 defined by an inner periphery 18a, an outer periphery 18b, a first side edge 19a and a second side edge 19b of the refiner disc 101, 201. When the refiner disc 101, 201 is attached to the refiner disc 30, 30*, the inner periphery 18a will be positioned closest to the center C of the refiner disc, while the outer periphery 18b will be positioned further from the center C, i.e. it has a greater radial distance from the center C than the inner periphery 18a. In this example, the refiner disc is a sector of a circle with an open center. Therefore, a plurality of such refiner discs are required to cover the surface of the refiner disc 30, 30*. However, the refiner discs may also have other geometric shapes.

[0039] The active surface 2 comprises a plurality of teeth 10 extending on the active surface 2 towards the outer periphery 18b of the refiner plate, thereby forming a plurality of grooves 19, wherein each groove 19 is formed between two adjacent teeth 10. The material to be refined in the refiner is conveyed along the grooves 19 towards the outer periphery 18b of the refiner plate 101, 201. At least some of the teeth 10 extend substantially parallel to each other. At least some of the teeth 10 may extend on the active surface 2 in a direction between the inner periphery 18a and the outer periphery 18b of the refiner plate. However, this may not be the case for all teeth 10. The active surface 2 further comprises a plurality of paddles 11, wherein each of said paddles 11 extends between two adjacent teeth 10. The grooves 19 may comprise one or more paddles 11, which are separated along the extension of the grooves 19. Thus, in the area defined by the adjacent teeth 10 and the at least two paddles 11, a substantially box-shaped area, referred to as box 23, is formed. A groove 19 may comprise one or more boxes 23, wherein a box 23 is delimited by two adjacent teeth 10 and two adjacent stops 11 arranged in the same groove 19. The last box 23a and the last stop 11a are defined as the box 23 and the stop 11 in the groove 19, respectively, which are located closest to the outer periphery 18b of the refiner plate compared to other possible boxes 23 and stops 11 arranged in the same groove 19. In a groove 19 in which only one box 23 or only one stop 11 is provided, they are defined as the last box 23a and the last stop 11a, respectively.

[0040] According to the present invention, at least three teeth 10 include a last box fluid connection 21, which is a fluid connection provided through the tooth 10, for connecting the last box 23a on one side of the tooth with the last box 23a on the other side of the tooth 10, so that the pressure between the two last boxes 23a can be balanced via the last box fluid connection 21. The last box fluid connection 21 is provided in the tooth 10, and the distance between it and the nearest last slurry stop 11a is between 0.0-15.0 mm, and the nearest last slurry stop extends from the tooth 10 to another adjacent tooth 10. In another embodiment of the present invention, the last box fluid connection 21 is provided in the tooth 10, and the distance between it and the nearest last slurry stop 11a is between 0.0-10.0 mm, and the nearest last slurry stop extends from the tooth 10 to another adjacent tooth 10.

[0041] As mentioned above, when used in a refiner for refining material, there will be a pressure peak in the refiner plate. The pressure peak will be located somewhere in the last box 23a. The last stop 11a in the groove 19 will form a barrier together with the section 12 of the tooth 10 connecting the last stop 11a, which separates the pressure between the two refiner discs 30, 30* from the pressure at the refiner plate outlet, which is the same as the pressure of the refiner housing. This barrier is called the pressure drop line 13a and is located at Figure 5 In the embodiment of the invention, the pressure in each last tank 23a is marked with a dotted line 13a. Without the last tank fluid connection 21 according to the invention, the pressure in each last tank 23a is independent and the risk of wear and leakage on the pressure drop line 13a will be highest in the last tank 23a with the highest pressure. By including a last tank fluid connection 21 in at least some of the teeth 10, the pressure in the last tank 23a will be balanced between at least some of the last tanks 23a, which will be advantageous. With a more balanced pressure, the peak pressure will be smaller and the wear on the refiner plates will be more evenly distributed.

[0042] exist Figure 5 In the embodiment shown, all teeth 10 that are part of the last box 23a comprise the last box fluid connection 21. There may be other teeth in the refiner plate that are not part of the last box 23a, for example Figure 5 1, where some of the shorter teeth are arranged closer to the inner periphery 18a of the refiner plate. Therefore, such teeth that do not extend to the outer periphery 18b of the refiner plate 101 do not require a fluid connection. Furthermore, not all teeth 10 that do extend to the outer periphery 18b and are part of the last box 23a need to include a last box fluid connection 21, even though this is not necessary. Figure 5 . According to the present invention, at least three teeth 10 comprise a last box fluid connection 21. In one embodiment of the present invention, a plurality of teeth 10 corresponding to at least half of the total number of teeth 10 provided in the refiner plate comprise a last box fluid connection 21. In another embodiment of the present invention, at least every other tooth 10 that is part of the last box 23a comprises a last box fluid connection 21. In yet another embodiment of the present invention, at least three adjacent teeth 10 each comprise a last box fluid connection 21. In yet another embodiment of the present invention, at least five adjacent teeth 10 each comprise a last box fluid connection 21.

[0043] In certain embodiments of the present invention, the last box fluid connection 21 has a width of 0.1-5.0 mm along the length extension of the tooth 10 disposed therein, and has a depth of 0.1-20.0 mm from the upper surface of the tooth 10 disposed therein.

[0044] Figure 6 Another embodiment of a refiner plate 201 according to the invention is shown. Most of the details are similar to those of Figure 5 The embodiments described are identical and these details are also given the same reference numerals and will not be described again in detail. In this embodiment of the invention, at least four final slurry barriers 11a arranged in adjacent grooves 19 are positioned so that they together form a continuous slurry barrier arranged along a smooth curve. This continuous slurry barrier will therefore constitute a pressure drop line 13b, which in this case is the same as the pressure drop line 13b. Figure 5 Compared with the pressure drop line 13a set in the fine grinding machine grinding plate 101, the line is set along a smooth curve. Figure 5 The weak point shown is arranged at the corner of the pressure drop line 13a of the refiner grinding plate 101, that is, the weak point at the corner between the last blade stop 11a and the section 12 of the blade connecting the last blade stop 11a and the other last blade stop 11a. Such a corner may be more affected by the pressure difference and may be exposed to greater wear, so that such a corner may leak more often than other positions. Figure 6 As shown in the refiner plate 201, the continuous slurry barrier along the smooth curve does not include such corners and therefore includes fewer weak points. Figure 6 In the illustrated configuration, the last tank fluid connection 21 can be easily arranged very close to the pressure drop line 13b. The last tank fluid connection 21 can be arranged to the cutter tooth 10 along a line or curve corresponding to the pressure drop line 13b, but its position is only a few millimeters closer to the inner periphery 18a than the pressure drop line 13b. In one embodiment, the distance between the pressure drop line 13b and the position of the last tank fluid connection 21 is 0-15 mm, while in another embodiment, the distance is 0-10 mm. By positioning the last tank fluid connection 21 close to the pressure drop line 13b, the risk of a pressure peak between the last tank fluid connection 21 and the pressure drop line 13b can be avoided or at least greatly reduced. As a result, the pressure balancing will be more effective.

[0045] exist Figure 6 In the embodiment shown, there are 8-9 last slurry stops 11a, which are positioned to form a continuous slurry stop arranged along a smooth curve. However, the number of last slurry stops 11a positioned to form a continuous slurry stop can vary. According to the invention, at least four last slurry stops are positioned to form a continuous slurry stop arranged along a smooth curve.

[0046] According to the invention, a refiner disc 30, 30* is also provided, which comprises at least one refiner disc 101, 201 according to the invention. The refiner disc 30, 30* may be a rotor disc or a stator disc. According to the invention, a refiner 100 for refining lignocellulosic material is also provided. The refiner comprises a refiner disc 30, 30*, which comprises at least one refiner disc 101, 201 according to the invention.

Claims

1. A refiner disc (101, 201) for use in a refiner disc (30, 30*) of a refiner (100) for refining lignocellulosic material, the refiner disc (1) having an active surface (2), the active surface being defined by an inner peripheral edge (18a), an outer peripheral edge (18b), a first side edge (19a) and a second side edge (19b) of the refiner disc (1), wherein: The effective surface (2) comprises: - a plurality of teeth (10) extending on the active surface (2) towards the outer periphery (18b) of the refiner plate, thereby forming a plurality of grooves (19), wherein each groove (19) is arranged between two adjacent teeth (10); and - a plurality of blade stops (11), wherein each blade stop (11) extends between two adjacent blade teeth (10), wherein at least some of the grooves (19) comprise one or more pulp stops (11) which are separated along the extension of the groove (19), and whereby at least some of the grooves (19) comprise one or more boxes (23), wherein a box (23) is delimited by two adjacent teeth (10) and two adjacent pulp stops (11) arranged in the same groove (19), wherein a last box (23a) and a last pulp stop (11a) are defined as a box (23) and a pulp stop (11) for a groove (19), respectively, and are positioned closest to the outer periphery (18b) of the refiner grinding plate compared to other possible boxes (23) and pulp stops (11) arranged in the same groove (19), At least three of the blade teeth (10) include a last box fluid connection part (21), which is a fluid connection part arranged through the blade tooth (10) and is used to connect the last box (23a) on one side of the blade tooth with the last box (23a) on the other side of the blade tooth (10), so that the pressure between the two last boxes (23a) can be balanced via the last box fluid connection part (21), wherein the last box fluid connection part (21) is arranged in the blade tooth (10) and the distance from the closest last slurry stop (11a) is between 0.0 and 15.0 mm, and the closest last slurry stop extends from the blade tooth (10) to another adjacent blade tooth (10).

2. The fine grinding machine grinding disc according to claim 1, characterized in that: The refiner grinding plate is configured to be located on a refiner disc (30, 30*) so as to cover at least a portion of a surface of the refiner disc and so that the inner peripheral edge (18a) of the refiner grinding plate is arranged closer to a center (C) of the refiner disc than the outer peripheral edge (18b).

3. The fine grinding machine grinding disc according to claim 1 or 2, characterized in that: The refiner grinding plate (1) is a sector of a circle with a central opening.

4. The fine grinding machine grinding disc according to claim 1 or 2, characterized in that: A number of teeth (10) corresponding to at least half of the total number of teeth (10) provided in the refiner plates comprise a last tank fluid connection (21).

5. The fine grinding machine grinding disc according to claim 1 or 2, characterized in that: At least every other blade tooth (10) that is part of the last box (23a) comprises a last box fluid connection (21).

6. The fine grinding machine grinding disc according to claim 1 or 2, characterized in that: At least three adjacent teeth each include a final tank fluid connection (21).

7. The fine grinding machine grinding disc according to claim 1 or 2, characterized in that: The last box fluid connection (21) has a width of 0.1-5.0 mm along the length extension of the blade tooth (10) arranged therein, and has a depth of 0.1-20.0 mm from the upper surface of the blade tooth (10) arranged therein.

8. The fine grinding machine grinding disc according to claim 1 or 2, characterized in that: At least four final barriers (11a) arranged in adjacent grooves (19) are positioned so that they together form a continuous barrier arranged along a smooth curve.

9. A refiner disc (30, 30*), characterized in that: Comprising at least one refiner grinding plate (101, 201) according to any one of claims 1 to 8.

10. The refiner disc (40) according to claim 9, characterized in that The refiner discs (30, 30*) are rotor discs or stator discs.

11. A refiner (100) for refining lignocellulosic material, characterized in that The refiner comprises a refiner disc (30, 30*) according to claim 9 or 10.

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