Apparatus for washing cellulose pulp

Abstract

A liquid distributor (110) for use in an apparatus for washing cellulosic pulp, the liquid distributor comprising a plurality of inlet orifices (111a-b) distributed along a longitudinal direction of the liquid distributor. Each inlet orifice is provided with a flow guide (112) forming a channel for each inlet orifice, the channel having a tangential opening (114) facing a tangential direction of a press roll, the opening being arranged adjacent to a chamber wall (105) to guide flow along the chamber wall of the apparatus. The flow guides of at least two adjacent inlet orifices can form longitudinally adjacent channels separated by means of a partition wall. Alternatively, the flow guides (112) are provided with one or more lateral openings (121) between their channels, the one or more lateral openings having a total effective flow area which is less than twice the effective flow area of each tangential opening.

Description

Technical Field

[0001] The present invention relates to a liquid dispenser for dispensing washing liquid in an apparatus for washing cellulose pulp, and an apparatus for washing cellulose pulp including such a liquid dispenser. Background Technology

[0002] Equipment for washing and / or dewatering cellulose pulp is known in the art. Many different types of washing equipment are available, some of which are based on press washing and include devices for pressing pulp to remove liquid.

[0003] The two-roll press washer is a well-known type of washing and dewatering equipment, consisting of two counter-rotating rolls with perforated outer surfaces. The pulp layer forms on the respective rolls and is conveyed in the direction of rotation into the so-called pressing zone between the rolls within a trough that partially surrounds the rolls. The liquid removed from the pulp, i.e., the filtrate, passes radially inward through the perforated roll surfaces and is guided to the ends of the pressing rolls, from where it is discharged. Washing liquid or other treatment liquids can be supplied to the pulp layer through inlets in the trough. The two-roll press washer utilizes displacement washing and pressing; in displacement washing, the dirty liquid (solution) in the pulp is replaced by a cleaner liquid added to the trough; in pressing, the dirty liquid is squeezed (pressed) out of the pulp, particularly in the pressing zone.

[0004] EP2620544 discloses a two-roll press washer, including a first and second movable sliding plate arranged within a trough, which guide the pulp suspension along the surface of the outer roller. Slots are formed between the first and second sliding plates and between the second sliding plate and the trough wall for introducing washing liquid in the direction of rotation (tangential direction). However, these slots may lead to uneven washing, i.e., the washing result varies along the axial length of the press washer. Summary of the Invention

[0005] The object of this invention is to provide a liquid dispenser and a washing device including such a liquid dispenser, which provides a more uniform washing effect. Another object is to provide such a liquid dispenser and device with a robust design. Yet another object is to provide a liquid dispenser and device that is easy to clean and maintain.

[0006] The present invention achieves these and other objectives by means of a liquid dispenser and device according to the following description.

[0007] According to a first aspect of the invention, a liquid distributor is provided in an apparatus for washing cellulose pulp, the apparatus comprising at least one rotatable press roll having a permeable outer surface, and at least one corresponding chamber wall that at least partially encloses the roll to define a pulp processing chamber between the roll and the wall. The liquid distributor is adapted to distribute liquid into the pulp processing chamber. The liquid distributor includes a plurality of inlet orifices distributed along a longitudinal direction of the liquid distributor, which is substantially parallel to the axis of rotation of the roll when the liquid distributor is mounted on the apparatus for washing cellulose pulp. Each inlet orifice is provided with a flow guide forming a groove for each inlet orifice, the groove having a substantially tangential opening facing the press roll in a tangential direction, the opening being arranged adjacent to the chamber wall to guide the flow along the chamber wall. At least two adjacent inlet orifices, or flow guides for each inlet orifice, form longitudinally adjacent channels, separated by one or more partition walls and / or with one or more lateral openings between the adjacent channels. The total effective flow area of ​​these one or more lateral openings is less than four times, or less than three times, preferably less than twice, the effective flow area of ​​each tangential opening. Alternatively, the total effective flow area of ​​the one or more lateral openings may be less than twice the effective flow area of ​​each tangential opening. In this embodiment, the liquid dispenser includes an elongated wall element adapted to connect to the chamber wall, with the inlet orifice formed in the wall element. In other embodiments, the inlet orifice is formed in the chamber wall, i.e., the chamber wall forms part of the liquid dispenser.

[0008] In other words, the channel formed by the flow guide of each inlet orifice has an opening facing substantially tangentially. The liquid distributor is configured such that, when installed in a device for washing cellulose pulp, the opening of the channel is arranged adjacent to the chamber wall, for example, between two chamber wall portions. Alternatively, the liquid distributor may form a chamber wall portion with a channel opening defined therein. Alternatively, the liquid distributor may form a chamber wall portion arranged adjacent to another chamber wall portion, defining a channel opening between them. At least two adjacent inlet orifices, or the flow guide of each inlet orifice, form longitudinally adjacent channels, which are separated by a partition wall, i.e., each inlet orifice forms a separate channel, such that all liquid flow from the respective inlet orifice is redirected through the tangential opening of the corresponding channel. Alternatively or additionally, the flow guides of at least two adjacent inlet orifices, or the flow guides of each pair of adjacent inlet orifices, may have one or more lateral openings between their channels, i.e., at least two, or each, channels are in fluid communication with its adjacent channel(s) via one or more lateral openings. One or more lateral openings between two adjacent flow guides / channels can have a total effective flow area less than twice the effective flow area of ​​each corresponding tangential opening.

[0009] This invention is based on the understanding that uneven washing in the prior art is due to the washing liquid flowing from areas of high drum pressure to areas of low drum pressure in the axial / longitudinal direction. This invention is also based on the understanding that substantially more uniform washing can be achieved by introducing washing liquid through multiple inlet orifices distributed along the axial / longitudinal direction of the drum, each equipped with a flow guide forming a groove, which not only guides the flow tangentially but also restricts the flow in the axial / longitudinal direction, and preferably prevents axial / longitudinal co-flow. This invention is further based on the understanding that optimized washing performance can be achieved through the flow guides, which have an effective flow area in the axial / longitudinal direction between adjacent grooves that is less than twice the effective flow area in the tangential direction.

[0010] It can be understood that axial, longitudinal, or lateral directions refer to directions parallel to the rotation axis of the press roll. Furthermore, it can be understood that the tangential direction refers to the tangential direction of the roll, which can also refer to the rotation direction of the roll.

[0011] In one embodiment, at least two adjacent inlet orifices or flow guides for each inlet orifice form longitudinally adjacent slots, which are separated by a partition wall along a portion of the tangential length of the slots to form one or more lateral openings.

[0012] In one embodiment, a partition wall between at least two longitudinally adjacent slots extends along the entire tangential length of the slot. In such an embodiment, there are no lateral openings between the slots. The partition wall may be provided between each pair of longitudinally adjacent slots to form a separate slot for each inlet orifice, with the partition wall extending along the entire tangential length of the slot.

[0013] In an embodiment, the flow guides for at least two adjacent inlet orifices are formed by a flow guiding device comprising a substantially tangentially extending flow reguiding wall and the partition wall. The partition wall not only restricts flow in the circumferential / longitudinal direction but also makes the flow guiding device more robust because it increases support for the flow guiding wall in the radial direction. One or more partition walls may be formed such that each channel has a cross-section that expands at least partially along its extension in the direction of liquid flow. This can be advantageous because the liquid flow is effectively guided forward.

[0014] In an embodiment, the slots of at least two adjacent inlet orifices, or all inlet orifices, are formed close to each other to form a common slot, thereby forming the single lateral opening along the entire tangential length of the slot. In other words, the slots are formed as a portion of the common slot. In such an embodiment, there are no partition walls(s) between the at least two adjacent inlet orifices or all inlet orifices forming the common slot. The common slot can be formed by a flow guiding device comprising a substantially tangentially extending flow reguiding wall, which can be substantially planar. In an embodiment, the flow reguiding wall can be releasably attached to a chamber wall. This can be advantageous because the slot can be easily cleaned.

[0015] In embodiments where the liquid dispenser includes an elongated wall element adapted to connect to the chamber wall, an inlet orifice is formed in the wall element, and a flow redirection wall can be releasably attached to the wall element, for example by means of a screw. This can be advantageous because the tank can be easily cleaned.

[0016] In an embodiment, the liquid dispenser may further include a throttling plate having at least two or more throttling orifices arranged downstream of and aligned with corresponding inlet orifices to throttle the liquid flow passing through it. Preferably, the throttling plate has a throttling orifice for each inlet orifice. At least two of the throttling orifices may have different diameters. The throttling plate may be formed separately from the flow guiding device so that it is replaceable by the user and releasably formed by the rest of the liquid dispenser. This is advantageous because the liquid flow through the inlet orifice can be adjusted by replacing the throttling plate. The throttling plate may be arranged to be sandwiched between the flow guiding device, or more specifically, between one or more partition walls and wall elements.

[0017] In an alternative embodiment, the inlet orifice may be provided with a throttling element, for example, in the form of a releasably attached fixed-diameter throttling orifice. This is a particularly advantageous embodiment when the inlet orifice is formed in the chamber wall. The throttling orifice may be threadedly attached to the chamber wall.

[0018] In another alternative embodiment, the inlet orifice may have an effective flow area suitable for a predetermined flow through each orifice, i.e., the inlet orifice itself acts as a throttling orifice. In particular, the inlet orifice may have different effective flow areas selected along the longitudinal direction of the liquid distributor in order to reduce flow variations between different inlet orifices.

[0019] According to a second aspect of the invention, an apparatus for washing cellulose pulp is provided, the apparatus comprising at least one rotatable press roll having a permeable outer surface, and at least one corresponding chamber wall that at least partially encloses the roll to define a pulp processing chamber between the roll and the wall, at least one pulp dispensing device extending along the length of the press roll, the pulp dispensing device comprising an inlet and an outlet, and arranged to dispense pulp onto the permeable outer surface through its outlet, and

[0020] At least one liquid dispenser according to a first aspect of the invention or an embodiment thereof.

[0021] The features of the above embodiments can be combined in any practically feasible manner to form embodiments having such combinations of features. Attached Figure Description

[0022] These and other aspects of the invention will now be described in more detail with reference to the accompanying drawings, which illustrate presently preferred embodiments of the invention, in which:

[0023] Figure 1 Existing technology equipment for washing cellulose pulp is shown;

[0024] Figure 2a -b illustrates an embodiment of a liquid distributor according to a first aspect of the invention, as well as a portion of the press rolls and chamber wall of an apparatus for washing cellulose pulp;

[0025] Figure 3a -b illustrates another embodiment of a liquid distributor according to a first aspect of the invention, as well as a portion of the press rollers and chamber wall of an apparatus for washing cellulose pulp; and

[0026] Figure 4a -b illustrates another embodiment of a liquid distributor according to a first aspect of the invention, as well as a portion of the press rolls and chamber wall of an apparatus for washing cellulose pulp. Detailed Implementation

[0027] Figure 1A prior art apparatus for washing cellulose pulp, in the form of a two-roll press washing machine, is shown, comprising two co-moving cylindrical press rolls 2. The press rolls 2 are arranged to rotate in opposite directions R, R' during operation and each has a permeable outer surface 4. The apparatus also includes a trough with chamber walls 5 that partially enclose the rolls 2 to define a pulp processing chamber 8 between the rolls and the corresponding chamber walls. Pulp is distributed onto the permeable outer surfaces 4 by means of a pulp distribution device 1. A pulp layer is formed on the permeable outer surfaces 4 of the rolls. The pulp layer is conveyed in the pulp processing chamber 8 in the rotational directions R, R' to be pressed at a pressing zone 3, where the distance between the press rolls 2 is minimized. The press rolls 2 include axial filtrate channels 6 for receiving filtrate from the pulp layer. The filtrate passes through the permeable roll surface 4 and is conveyed toward the ends of the press rolls 2, from which it is output. Washing liquid is supplied to the pulp layer in the trough chamber 8 via a liquid distributor 10. The pulp is output by means of a discharge screw 7.

[0028] Figure 2a -b illustrates an embodiment of a liquid dispenser 110 according to a first aspect of the invention, and... Figure 1 The press rollers and part of the chamber wall of the device of the same type shown. The liquid distributor 112 therefore replaces... Figure 1 One or two liquid dispensers 10. Figure 2a A cross-section of the press roll 102 and a portion of the chamber wall 105 is shown, defining the pulp processing chamber 108 between them. Figure 2b A radially outward view of the chamber wall 105, seen from inside the press roll in the radial direction, is shown. The liquid distributor 110 includes a plurality of inlet orifices 111a-b distributed along the longitudinal direction L of the liquid distributor. In this embodiment, the inlet orifices are formed as through holes in the chamber wall 105. Each inlet orifice is provided with a flow guide 112, which forms a groove 113a-b for each inlet orifice. Each groove has a tangential opening 114 facing a substantially tangential direction toward the press roll. The openings are arranged adjacent to the chamber wall 105 to guide the flow along the chamber wall.

[0029] All slots are formed adjacent to each other to form a common slot, such as a lateral opening 121 formed along the entire tangential length 117a of the slot. Thus, the flow guides 112 of each pair of adjacent inlet orifices have a lateral opening 121 between their slots. Slots 113a-b can therefore also refer to the slot portions of the common slot. In the figures, imaginary dashed lines are shown between the inlet orifices to indicate the corresponding slot portion for each inlet orifice. The total effective flow area of ​​the lateral openings is less than twice the effective flow area of ​​each tangential opening. In this embodiment, the slots have a constant height as seen in the radial direction, meaning that the tangential length 117a is longer than the longitudinal length / width 117b of each slot portion, but shorter than twice that longitudinal length. A common channel is formed by a flow guiding device, which includes a substantially tangentially extending flow reguide wall 116. This flow reguide wall 116 is positioned at a distance from the chamber wall 105 by means of spacers 116', and may be integrally formed with the flow reguide wall or be part of the flow guiding device. The flow reguide wall 116 is releasably attached to the chamber wall 105, for example, by means of screws (e.g., 122a-b) passing through the spacers 116'. Figure 2b As shown. In an embodiment, the entire flow guiding device, including wall 116 and spacer 116', is releasably attached to chamber wall 105.

[0030] Figure 3a -b illustrates another embodiment of the liquid dispenser 210 according to the first aspect of the invention, and with Figure 1 The press rollers and part of the chamber wall of the device of the same type shown. The liquid distributor 210 therefore replaces... Figure 1 One or two liquid dispensers 10. Figure 3a A cross-section of the press roll 202 and a portion of the chamber wall 205 is shown, defining the pulp processing chamber 208 between them. Figure 3b A radially outward view of the chamber wall 205, seen from inside the press roll in the radial direction, is shown. The liquid distributor 210 includes a plurality of inlet orifices 211a-b distributed along the longitudinal direction L of the liquid distributor. In this embodiment, the inlet orifices are formed as through holes in the chamber wall 205. Each inlet orifice is provided with a flow guide 212, which forms a groove 213a-b for each inlet orifice. Each groove has a tangential opening 214 facing a substantially tangential direction towards the press roll. The openings are arranged adjacent to the chamber wall 205 to guide the flow along the chamber wall. A flow redirecting wall 216 is releasably attached to the chamber wall 205, for example, by means of a screw (e.g., ...). Figure 3b As shown, to be consistent with Figure 2b (Corresponding method).

[0031] Each inlet orifice is provided with a releasably attachable fixed-diameter throttling orifice 220 (e.g., Figure 3b(As shown by the dashed line below the chamber wall 205). The throttling orifice 220 can be threadedly attached to the chamber wall 205. The throttling orifice has a through-hole with a diameter smaller than that of the inlet orifice, thereby throttling the flow.

[0032] The flow guides 212 of each pair of adjacent inlet orifices form longitudinally adjacent slots separated by partition walls (e.g., 215) that extend along the entire tangential length of the slots. Therefore, unlike... Figure 2a In the embodiment of -b, there are no lateral openings between the slots. For example... Figure 3b As shown, the partition wall (e.g., 215) is formed such that each channel has a cross-section that expands to the left along its extension in the direction of liquid flow, i.e., in the figure. All flow guides 212 are formed by flow guiding devices, which include a substantially tangentially extending flow reguide wall 216 and a partition wall. The partition wall is integrally formed as a unit, which also functions as a spacer for arranging the flow reguide wall 216 at a distance from the chamber wall 205. Thus, the partition wall unit is sandwiched between the flow reguide wall 216 and the chamber wall 205.

[0033] Figure 4a -b illustrates another embodiment of the liquid dispenser 310 according to the first aspect of the invention, and... Figure 1 The press rollers and part of the chamber wall of the device of the same type shown. The liquid distributor 310 therefore replaces... Figure 1 One or two liquid dispensers 10. Figure 4a A cross-section of the press roll 302 and a portion of the chamber wall 305 is shown, defining the pulp processing chamber 308 between them. Figure 4b A radially outward view of the chamber wall 305, seen from inside the press roll in the radial direction, is shown. The liquid distributor 310 includes a plurality of inlet orifices 311a-b distributed along the longitudinal direction L of the liquid distributor. The liquid distributor 310 includes an elongated wall element 318 attached to the chamber wall 305. In other embodiments, the wall element 318 is releasably attached to the chamber wall 305, for example, by means of screws. The inlet orifices 311a-b are formed in the wall element. The wall element is arranged within a longitudinal groove in the chamber wall 305, and its inner surface 318', together with the flow redistribution wall 316, forms a portion of the overall chamber wall, which partially encloses the roll 302.

[0034] The flow guides 312 of each pair of adjacent inlet orifices form longitudinally adjacent slots separated by a partition wall 315, which extends along the entire tangential length of the slot, in a manner similar to Figure 3a -b method. For example Figure 4bAs shown, the partition wall (e.g., 315) is formed such that each channel has a cross-section that expands to the left along its extension in the liquid flow direction, i.e., in the figure. All flow guides 312 are formed by flow guiding devices, which include substantially tangentially extending flow reguiding walls 316 and partition walls 315. In this embodiment, just as Figure 3a -b, all partition walls are formed as a unit, which also functions as a spacer for arranging wall 316 at a certain distance from wall element 318.

[0035] The liquid distributor also includes a throttling plate 319 having a plurality of throttling orifices (e.g., 319a-b). The throttling plate is arranged such that its throttling orifices are downstream of and aligned with the corresponding inlet orifices to throttle the liquid flow passing through it.

[0036] With Figure 2b In a corresponding manner, the flow guidance devices 315 and 316, for example, utilize... Figure 4b The screw shown is releasably attached to the wall element 318. The throttle plate 319 is formed separately from the flow guides 315, 316 so that it is replaceable by the user. The throttle plate 319 is arranged to be sandwiched between the flow guide and the wall element 318.

[0037] Each inlet orifice is provided with a flow guide 312, which forms a groove 313a-b for each inlet orifice. Each groove has a tangential opening 314 facing the substantially tangential direction of the press roll. The opening 314 is arranged adjacent to the wall element surface 318' to guide flow along the chamber wall.

[0038] The above description and accompanying drawings should be considered as non-limiting examples of the invention. Those skilled in the art will recognize that several changes and modifications can be made within the scope of the invention. For example, the number of inlet orifices and the spacing between them can be varied. Furthermore, as... Figure 3a The partition walls shown in -b and 4a-b do not necessarily need to extend along the full length of the trench.

Claims

1. An apparatus for washing cellulose pulp, the apparatus comprising: - A rotatable press roll having a permeable outer surface, and at least one corresponding chamber wall, the at least one corresponding chamber wall at least partially enclosing the rotatable press roll to define a pulp processing chamber between the rotatable press roll and the chamber wall. - At least one pulp distribution device extending along the length of the rotatable press roll, the pulp distribution device including an inlet and an outlet, and arranged to distribute pulp onto the permeable outer surface through its outlet, and - At least one liquid dispenser, said at least one liquid dispenser being adapted to dispense liquid into the slurry processing chamber, said liquid dispenser comprising: - Multiple inlet orifices distributed along the longitudinal direction L of the liquid distributor, the longitudinal direction being substantially parallel to the rotation axis of the rotatable press roller, wherein the inlet orifices are formed in the chamber wall, or The liquid dispenser includes an elongated wall element adapted to be connected to the chamber wall, and the inlet orifice is formed in the elongated wall element; - Each of the inlet orifices is provided with a flow guide for guiding flow, the flow guide forming a groove for each inlet orifice, the groove having a tangential opening facing the tangential direction of the rotatable press roll, the tangential opening being arranged adjacent to the chamber wall to guide flow along the chamber wall. In this configuration, the flow guides of at least two adjacent inlet orifices form longitudinally adjacent slots separated by a partition wall extending along the entire tangential length of the longitudinally adjacent slots, or In this embodiment, at least two adjacent inlet orifices of the flow guide have one or more lateral openings between their slots, the total effective flow area of ​​the one or more lateral openings being less than twice the effective flow area of ​​each of the tangential openings.

2. The device according to claim 1, characterized in that, When the flow guides of at least two adjacent inlet orifices have one or more lateral openings between their slots, the flow guides of at least two adjacent inlet orifices form longitudinally adjacent slots, which are separated by a partition wall along a portion of the tangential length of the slots to form the one or more lateral openings.

3. The device according to claim 1, characterized in that, The flow guides of at least two adjacent inlet orifices are formed by a flow guiding device, which includes a substantially tangentially extending flow reguiding wall and the partition wall.

4. The device according to claim 1, characterized in that, The partition wall is formed such that each of the grooves has a cross-section that expands at least partially along its extension in the direction of liquid flow.

5. The device according to claim 1, characterized in that, When the flow guides of at least two adjacent inlet orifices have one or more lateral openings between their slots, the slots of the at least two adjacent inlet orifices are formed to be closely adjacent to each other as slot portions of a common slot, so as to form the one lateral opening along the entire tangential length of the slot.

6. The device according to claim 5, characterized in that, The common channel is formed by a flow guiding device, which includes a substantially tangentially extending flow reguiding wall.

7. The device according to claim 3 or 6, characterized in that, When the liquid dispenser includes an elongated wall element adapted to be connected to the chamber wall and the inlet orifice is formed in the elongated wall element, the flow redistribution wall is releasably attached to the elongated wall element.

8. The device according to claim 1, characterized in that, When the liquid distributor includes an elongated wall element adapted to connect to the chamber wall and the inlet orifice formed in the elongated wall element, the liquid distributor further includes a throttling plate having at least two throttling orifices arranged such that the at least two throttling orifices are downstream of at least two inlet orifices to throttle the liquid flow passing through it.

9. The device according to claim 8, characterized in that, The throttling plate is formed separately from the flow guiding device so that it can be replaced by the user.

10. The device according to claim 9, characterized in that, The throttling plate is arranged between the flow guiding device and the elongated wall element.

11. The device according to any one of claims 8 to 10, characterized in that, At least two of the throttling orifices have different diameters.

12. The device according to claim 3 or 6, characterized in that, The flow redistribution wall can be releasably attached to the chamber wall.

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