Water absorption roller of fiber web machine and combined squeezer
By designing the perforated roller shell and vacuum box in the water absorption roller of the fiber web machine, equipped with a fluid collector and fluid discharge equipment, the problem of insufficient vacuum box capacity is solved, more efficient water removal and higher dryness are achieved, and the productivity and dehydration efficiency of the fiber web machine are improved.
Patent Information
- Application Number
- CN202411499170.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-10-27
- Filing Date
- 2024-10-25
- Publication Date
- 2025-04-29
AI Technical Summary
The existing fiber web machines have insufficient capacity for water absorption roller vacuum boxes, resulting in uneven water collection, irregular humidity distribution, and may cause water overflow, rewetting of fabrics or damaging the fiber web, thereby limiting dehydration capacity and productivity.
A water absorbing roller with a perforated roller shell is designed, with a built-in vacuum box defining one or more vacuum chambers together with the roller shell, and is equipped with a fluid collector for collecting water, which is connected to a fluid discharge device to ensure effective removal of excess free water.
Through the improved water absorption roller design, the dehydration efficiency and productivity of the fiber web machine are improved, water circulation and fiber web damage are avoided, and higher dryness and lower energy consumption are ensured.
Smart Images
Figure CN119900190A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a suction roll of a fiber web machine, which has a perforated roll shell in which a vacuum box is located, which together with the roll shell defines one or more vacuum chambers. Background Art
[0002] The suction roll has a perforated roll shell, and inside the roll shell there is a vacuum box, which forms a vacuum system for the suction roll. In the known vacuum box, there are two vacuum chambers. The side walls of the vacuum box are provided with end seals and axial seals that are in contact with the inner surface of the roll shell. The end seals are also called deckle seals. Each vacuum chamber is thus defined. A vacuum is generated in the vacuum chamber, a vacuum zone is formed on the surface of the roll shell, and the vacuum removes water through the roll shell.
[0003] Suction rolls are usually located in the press section of a fiber web machine. Furthermore, usually at least one counterroll forms a press nip together with the suction roll. Furthermore, the fabric supporting the fiber web runs through the press nip. By pressing, water is removed from the fiber web. Most of the water enters the suction roll through the soaked felt, while part of the water enters the felt conditioning system.
[0004] In practice, however, the capacity of the vacuum box may be insufficient. As a result, the water collection is uneven, making the moisture profile of the fiber web irregular. On the other hand, the suction roll may even be filled to overflowing. In other words, excess water overflowing into the vacuum chamber returns to the holes in the roll shell and may burst out from the suction roll. The water just rotates around the suction roll. This rewets the fabric or even damages the fiber web itself. Web breaks may also occur. Furthermore, due to the limited dewatering capacity, it is difficult to increase the productivity of the fiber web machine. In the worst case, the production speed of the fiber web machine must be reduced. Summary of the invention
[0005] The object of the present invention is to provide a new suction roll of a fiber web machine with improved dewatering efficiency and better adjustability. The features of the suction roll according to the invention are described herein. Another object is to provide a new combi press of a fiber web machine with improved dewatering performance. The combi press is equipped with a suction roll according to the invention. Any rewetting problems can thus be avoided and the production speed of the fiber web machine can be increased. The features of the combi press according to the invention are described herein. Moreover, existing suction rolls currently in use can be easily upgraded to obtain a suction roll according to the invention. The suction roll has simple components and requires little energy. In fact, energy can be saved when dewatering is additionally ensured by a unique and surprising construction. At the same time, the number of web breaks will be reduced and the fiber web will be drier after the combi press than before.
[0006] The present application provides a suction roll of a fiber web machine, the suction roll having a perforated roll shell, a vacuum box inside the roll shell, the vacuum box defining one or more vacuum chambers together with the roll shell, wherein the vacuum box is equipped with a fluid collector for collecting water, and the fluid collector is connected to a fluid discharge device.
[0007] The present application also provides a combined press of a fiber web machine, the combined press comprising two bottom press rolls, the two bottom press rolls being arranged against a common suction roll, the suction roll having a perforated roll shell, the interior of the roll shell having a vacuum box, the vacuum box together with the roll shell defining one or more vacuum chambers, wherein the vacuum box is equipped with a fluid collector for collecting free water, and the fluid collector is connected to a fluid discharge device. BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The present invention is described in detail below with reference to the accompanying drawings, which show some embodiments of the present invention, wherein:
[0009] Figure 1 A known press section of a fiber web machine is shown;
[0010] Figure 2 shows a cross section of a suction roll according to the invention;
[0011] Figure 3a A side view of a suction roll according to the invention is shown in principle;
[0012] Figure 3b Shows Figure 3a Modification of the suction roll shown. DETAILED DESCRIPTION
[0013] Figure 1A known press section of a fiber web machine is shown. Some parts of the preceding forming section are also shown. Here, a fiber web W enters the press section from above a forming wire 10 belonging to the forming section. Before the so-called combined press 11, the fiber web W runs together with the forming wire 10 through a press nip 12 formed by a suction roll 13 and a lump breaker 14. This press nip increases the strength of the fiber web and reduces the amount of fiber lumps in the fiber web. Subsequently, the fiber web W enters the combined press 11. The combined press 11 comprises two press nips 15 and 16 formed by a suction roll 17 together with two bottom press rolls 18 and 19. In addition to the forming wire 10, two press felts 20 and 21 also run through the combined press 11. The press felts support the fiber web during two consecutive pressing events. In the first press nip 15, the fiber web W is located between the forming wire 10 and the first press felt 20. The second press nip 16 is a double felt structure. In other words, the fiber web is located between the two press felts 20 and 21. After the combined press 11, the fiber web W passes through an open draw 22 to a shoe press 23 and then to a drying section (not shown).
[0014] Figure 2 The combined press 11 is shown in an enlarged view. The perforated roll shell 24 of the suction roll 17 is shown in section to show the internal structure of the suction roll 17. The suction roll is a component of a fiber web machine. In practice, a fiber web machine has a plurality of suction rolls. However, water can cause the above-mentioned problems, especially in a combined press. As shown, the suction roll 17 has a perforated roll shell 24. Grooves or other shapes can also be provided on the outer surface of the roll shell to increase the void volume for water. Inside the roll shell there is a vacuum box 25, which together with the roll shell 24 defines one or more vacuum chambers 26 and 27. Figure 2 Only the axial seal is shown. The vacuum box 25 has a plurality of walls and the axial seals and the end seals are supported on these walls, defining a vacuum chamber against the roll shell. In one end of the suction roll 17 there is a channel 28 with a partition 29. In this way different vacuum levels can be created. In other words, the vacuum level in the first vacuum chamber 26 is different from the vacuum level in the second vacuum chamber 27. Water leaves the suction roll 17 through the channel 28 together with the gas flow. The corresponding vacuum lines 30 and 31 are shown in FIG. Figure 3a and Figure 3b The vacuum line is connected to a vacuum source, such as one or more blowers (not shown).
[0015] The first vacuum chamber 26 starts before the first press nip 15 and ends after the second press nip 16. The first vacuum chamber 26 forms a so-called suction zone on the surface of the suction roll. The vacuum between the first press nip 15 and the second press nip 16 keeps the fiber web W in contact with the first press felt 20 while sucking water into the suction roll 17. The first vacuum chamber 26 is delimited by a first axial seal 32 and a second axial seal 33. Correspondingly, the second vacuum chamber 27 is delimited by a third axial seal 34 and a fourth axial seal 35. The second vacuum chamber 27 forms a so-called cleaning zone on the surface of the suction roll. The vacuum of the second vacuum chamber 27 empties the pores of the roll shell 24 so that the suction roll can receive water again in the first press nip. If the dewatering capacity of the suction roll is insufficient, the water level in the vacuum chamber will rise, thereby hindering the cleaning of the roll shell.
[0016] According to the present invention, the vacuum box 25 is equipped with a fluid collector 36 for collecting water. In practice, the fluid is mainly water, but there may also be some air, fibrous debris and fibers. Therefore, the fluid collector is more like a water collector. In addition, the water is free water located in the suction roll that has been sucked by the vacuum chamber. In other words, the free water is ready to be discharged from the suction roll. In addition, the fluid collector 36 is connected to the fluid discharge device 37. In practice, water is collected by the fluid collector, and then the collected water is removed by the fluid discharge device 37. These two components are simple and small in size. Therefore, it is easy to integrate the components into the suction roll and the combined press.
[0017] like Figure 2 As shown, the fluid collector 36 is connected to the last of the vacuum chambers 26 and 27 in the direction of rotation 38 of the roller shell 24. In practice, the last vacuum chamber forming the cleaning zone should be sufficiently empty to avoid rewetting and other problems. By means of the fluid collector according to the invention, excess free water is effectively removed. Thus, proper functioning of the suction roll is ensured.
[0018] The fluid collector can be freely mounted inside the suction roll. Advantageously, however, the fluid collector 36 is located below the vacuum chamber 26 or 27 in question and in the wall 39 of the vacuum box 25, arranged to collect water in the direction of gravity. In fact, the fluid collector acts as the lowest component of the vacuum chamber. Therefore, water will naturally enter the fluid collector by gravity. At the same time, the fluid discharge device 37 mainly removes water, which improves efficiency and keeps the size of the component small. In addition, the fluid collector 36 is far away from the roller shell 24 and its suction opening. Therefore, the rotation of the roller shell does not disturb the collection of water.
[0019] Surprisingly, even a small fluid collector is sufficient to remove excess free water. In practice, the fluid collector covers only a portion of the length of the vacuum box in the axial direction. In general, the length L of the fluid collector is 10%-20% of the length of the vacuum box. In practice, the length L of the fluid collector 36 is 600 to 1200 mm. Basically, a single-sized fluid collector is suitable for all sizes of suction rolls. However, the larger the suction roll, the larger the volume or the longer the fluid collector. As soon as water enters the fluid collector, the fluid discharge device will remove it. If the amount of water increases, the fluid collector will be emptied more frequently.
[0020] In the illustrated embodiment, the fluid collector 36 is a trough 40 located at one end of the vacuum box 25. Although the trough 40 can be installed at other locations of the vacuum box (e.g., in the middle of the vacuum box), it is easiest to implement the trough 40 at the end. In fact, excess water will naturally collect at the end of the vacuum box. Therefore, free water will flow to the trough located at the end of the vacuum box.
[0021] The shape and size of the trough can vary. Advantageously, the trough 40 has an inclined bottom 41. This will make the water collected in the fluid collector level. Again, gravity helps the water to collect. Here, the bottom 41 is inclined towards the end of the fluid collector 36. At this point there is a suction line 42 connected to the lower part 43 of the bottom 41 of the fluid collector 36. The suction line 42 begins with a suction opening 51. In this way, the fluid collector is completely emptied through the fluid discharge device 37. The suction line 42 can be as shown. Figure 3a Through the fluid collector 36 as in Figure 3b In addition, the fluid discharge device 37 includes a water separator 44, which is located outside the suction roll 17 and is connected to the fluid collector 36 via an independent suction line 42. Since the suction line 42 is located at the lower part 43 of the bottom 41, when there is free water in the suction roll, the suction line 42 is below the water surface. Therefore, the water tank is completely emptied. In addition, the water separator 44 can also be used for other devices to remove water from the air.
[0022] As mentioned above, the suction roll 17 is connected to a vacuum source 45, from which the vacuum is transmitted to the vacuum chamber of the vacuum box. The fluid discharge device 37 according to the invention also makes use of the same vacuum source 45. In practice, the water separator 44 is connected to the vacuum source 45 via a vacuum line 46. In this way, only a very small number of simple components are required to ensure effective dewatering and to ensure effective removal of free water.
[0023] In the embodiment shown, the vacuum line 46 has a control valve 47. Thus, the fluid discharge device 37 can be adjusted. However, the vacuum level required for water removal is slightly higher than the vacuum in the roll, and the vacuum line can be smaller. Thus, the fluid discharge device 37 can operate even without a control valve. In fact, the water separator will always operate. When the water level drops to the lower part 43 and air also starts to flow to the water separator 44, the vacuum in the water separator 44 automatically drops to almost the same level (or the same level) as the vacuum in the vacuum box. This means that the drainage will find its own balance and all the water entering the fluid collector will be removed. This is a self-controlled system. If the vacuum in the water separator 44 is lower than the vacuum in the suction roll 17, the flow direction will be towards the suction roll. Therefore, the water separator 44 is connected to a higher vacuum than the vacuum box. The fluid discharge device 37 will automatically start to operate again and will adjust according to the amount of free water. In other words, when the fluid collector becomes empty and some air enters through the suction line, the air will temporarily cut off the drainage. When there is enough water to be removed from the fluid collector, drainage and vacuum differential are automatically restored. The vacuum line 46 is small, so when there is water to be removed, the vacuum in the water separator 44 is increased by the vacuum source 45. When air enters with the water or only air enters, the vacuum at the vacuum source 45 is automatically the same as or slightly higher than the vacuum tank pressure. When there is water to be removed at the fluid collector 36, the vacuum will automatically increase due to less air from the vacuum tank and water removal will begin. In fact, by effectively removing water from the fluid collector, the vacuum source can be adjusted down, thereby saving energy, or a higher vacuum level can be achieved at the vacuum tank due to the reduced losses in the air outlet due to the reduced water passing through at the same time. In the suction roll according to the present invention, most of the water is removed by the fluid discharge device and the remaining water is removed by the vacuum outlet of the suction roll.
[0024] Figure 3a and Figure 3b Two embodiments are shown. Figure 3a In the embodiment, the water separator 44 is arranged to fall to the water lock tank 48, so no further energy is required. Figure 3b In the embodiment, the water separator 44 is arranged to discharge to an extraction pump 49, by which the removed water is further pumped out. Figure 3a and Figure 3b Also shown is a trim seal 50 .
[0025] By means of the suction roll according to the invention, a combined press of a fiber web machine can be operated efficiently without problems. Excess free water is removed safely and with low energy consumption. Furthermore, the required components are simple, robust and require little control. The vacuum level also remains stable when the excess water does not fill up the vacuum channel cross section. At the same time, the required vacuum level can be achieved with a smaller vacuum pump, thereby further reducing energy consumption. On the other hand, even higher vacuum levels can be achieved with existing vacuum sources. Furthermore, the length of the clean zone can be reduced, resulting in higher vacuum levels inside the suction roll and less air flow through the roll shell, without the need to cover the holes in the clean zone with a press felt. The vacuum in the clean zone (i.e. the air flow through the roll shell) is required to prevent water circulation on top of the suction roll.
[0026] The control valve described above is used to control the vacuum level in the water separator. In practice, the airflow required in the fluid collector is very small. Therefore, the vacuum line can be small. The vacuum in the water separator varies and the vacuum level is not much higher than in the clean area. During operation, the vacuum level in the water separator fluctuates up and down, but only by a few kilopascals. This means that the fluid collector is not always full. When the fluid collector is empty, more air enters and the vacuum in the water separator decreases and the drainage stops. Then, the fluid collector becomes full again and the vacuum in the water separator starts to increase because no air enters. This starts the drainage and the fluid collector is emptied. This cycle repeats itself. In practice, the vacuum level in the clean area is not disturbed because the airflow through the water separator is very small. The control valve can be used to adjust how quickly the drainage starts again after it has stopped.
Claims
1. A suction roll of a fiber web machine, the suction roll (17) having a perforated roll shell (24), inside which there is a vacuum box (25), which together with the roll shell (24) defines one or more vacuum chambers (26, 27), characterized in that The vacuum box (25) is equipped with a fluid collector (36) for collecting water, and the fluid collector (36) is connected to a fluid discharge device (37).
2. The suction roller according to claim 1, characterized in that: The fluid collector (36) is connected to the vacuum chambers (26, 27), advantageously to the last one of the vacuum chambers (26, 27) in the direction of rotation (38) of the roller shell (24).
3. The suction roller according to claim 2, characterized in that: The fluid collector (36) is located below the vacuum chambers (26, 27) and in a wall (39) of the vacuum box (25) and is arranged to collect water under the direction of gravity.
4. The suction roller according to claim 3, characterized in that: The fluid collector (36) serves as the lowest component of the vacuum chamber (26, 27).
5. The suction roll according to any one of claims 1 to 4, characterized in that The length (L) of the fluid collector (36) in the axial direction is 600-1200 mm.
6. The suction roll according to any one of claims 1 to 5, characterized in that The fluid collector (36) is a water trough (40) located in one end of the vacuum box (25).
7. The suction roller according to claim 6, characterized in that: The water tank (40) has an inclined bottom (41).
8. The suction roll according to any one of claims 1 to 7, characterized in that The fluid discharge device (37) comprises a water separator (44) which is located outside the suction roll (17) and is connected to the fluid collector (36) through an independent suction line (42).
9. The suction roll according to claim 8, characterized in that: The water suction line (42) is connected to the lower portion (43) of the fluid collector (36).
10. The suction roll according to claim 9, characterized in that: The suction roll (17) is equipped with a vacuum source (45), and the water separator (44) is connected to the vacuum source (45) via a vacuum line (46).
11. The suction roll according to claim 10, characterized in that: The vacuum line (46) has a control valve (47).
12. The suction roll according to any one of claims 8 to 11, characterized in that The water separator (44) is arranged to discharge into a water lock tank (48).
13. The suction roll according to any one of claims 8 to 11, characterized in that The water separator (44) is arranged to discharge to a water extraction pump (49).
14. Combined press of a fiber web machine, comprising two bottom press rolls (18, 19) arranged against a common suction roll (17), the suction roll having a perforated roll shell (24), the interior of the roll shell having a vacuum box (25), which together with the roll shell (24) defines one or more vacuum chambers (26, 27), characterized in that The vacuum box (25) is equipped with a fluid collector (36) for collecting free water, and the fluid collector (36) is connected to a fluid discharge device (37).
15. The combined press according to claim 14, characterized in that The suction roller (17) is a suction roller (17) according to any one of claims 2 to 13.