SYSTEM AND METHOD FOR CLEANING OF BELTS AND/OR FABRICS USED ON THROUGH AIR DRYING PAPERMAKING MACHINES

Abstract

A method for cleaning a belt of a through air drying papermaking machine in which a high pressure shower is configured to traverse across a width of the belt of the papermaking machine while ejecting water onto the belt, and a vacuum box is operatively connected to the high pressure shower. The high pressure shower has a width that is less than a full width of the belt.

Claims

1. A system for cleaning a belt or through air drying fabric of a through air drying papermaking machine, comprising: a high pressure shower configured to traverse across a width of the belt or through air drying fabric of the papermaking machine while ejecting water onto the belt or through air drying fabric, the first high pressure shower having a full width that is less than a full width of the belt or through air drying fabric; and a vacuum box operatively connected to the high pressure shower.

2. The system of claim 1, wherein the high pressure shower is configured to eject water onto a sheet-contacting side of the belt or through air drying fabric.

3. The system of claim 1, wherein the high pressure shower is configured to eject water onto a non-sheet-contacting side of the belt or through air drying fabric.

4. The system of claim 3, further comprising a second high pressure shower configured to traverse across the width of the belt or through air drying fabric of the papermaking machine while ejecting water onto a sheet-contacting side of the belt or through air drying fabric, the second high pressure shower having a full width that is less than a full width of the belt or through air drying fabric; and a second vacuum box operatively connected to the second high pressure shower.

5. The system of claim 1, wherein the belt or through air drying fabric is a structuring fabric.

6. The system of claim 1, wherein the belt or through air drying fabric is a reel belt.

7. The system of claim 1, wherein the high pressure shower is positioned adjacent a machine roll upon which the belt or through air drying fabric is wrapped 30° to 270° around a circumference of the machine roll.

8. The system of claim 1, wherein the vacuum box has a curved shape corresponding to the circumference of the machine roll.

9. The system of claim 1, wherein the high pressure shower is a needle shower.

10. The system of claim 1, wherein the needle shower comprises a plurality of nozzles.

11. The system of claim 10, wherein the plurality of nozzles are configured to eject round water jets with a diameter of 0.15 mm to 0.55 mm.

12. The system of claim 10, wherein the plurality of nozzles are configured to eject round water jets with a diameter of 0.2 mm to 0.3 mm in diameter.

13. The system of claim 10, wherein pressure of the water jets is 20 Bar to 600 Bar.

14. The system of claim 10, wherein pressure of the water jets is 100 Bar to 300 Bar.

15. The system of claim 10, wherein the needle shower comprises 1 to 50 nozzles.

16. The system of claim 10, wherein the needle shower comprises 1 to 20 nozzles.

17. The system of claim 10, wherein the needle shower comprises 1 to 10 nozzles.

18. The system of claim 1, further comprising an air knife configured to traverse across the width of the belt or through air drying fabric of the papermaking machine while blowing air onto the belt or through air drying fabric in a direction towards the vacuum box.

19. The system of claim 1, wherein the belt or through air drying fabric comprises a multi-layer structured tissue fabric without direct channels extending perpendicularly through the fabric.

20. The system of claim 20, wherein the system comprises a sheet side and rolls side multi-unit traversing system that cleans each side separately.

21. The system of claim 1, wherein the belt or through air drying fabric is a structured tissue fabric with air flow permeability between 250 to 500 cfm.

22. A method for cleaning a belt or through air drying fabric of a through air drying papermaking machine, comprising: ejecting water onto the belt or through air drying fabric with a high pressure shower while simultaneously traversing the high pressure shower across a width of the belt or through air drying fabric of the papermaking machine, the high pressure shower having a full width that is less than a full width of the belt or through air drying fabric; and removing contamination from the belt or through air drying fabric with a vacuum box operatively connected to the high pressure shower.

23. The method of claim 22, wherein the water is ejected onto a sheet-contacting side of the belt.

24. The method of claim 22, wherein the water is ejected onto a non-sheet-contacting side of the belt.

25. The method of claim 24, further comprising ejecting water onto the sheet-contacting side of the belt or through air drying fabric with a second high pressure shower while traversing the second high pressure shower across the width of a belt of the papermaking machine, the second high pressure shower having a full width that is less than a full width of the belt; and removing contamination from the belt or through air drying fabric with a second vacuum box operatively connected to the second high pressure shower.

26. The method of claim 22, wherein the belt is a structuring fabric.

27. The method of claim 22, wherein the belt is a reel belt.

28. The method of claim 22, wherein the high pressure shower is positioned adjacent a machine roll upon which the belt is wrapped 30° to 270° around a circumference of the machine roll.

29. The method of claim 22, wherein the vacuum box has a curved shape corresponding to the circumference of the machine roll.

30. The method of claim 22, wherein the high pressure shower is a needle shower.

31. The method of claim 22, wherein the needle shower comprises a plurality of nozzles.

32. The method of claim 31, wherein the plurality of nozzles are configured to eject round water jets with a diameter of 0.15 mm to 0.55 mm.

33. The method of claim 31, wherein the plurality of nozzles are configured to eject round water jets with a diameter of 0.2 mm to 0.3 mm in diameter.

34. The method of claim 31, wherein pressure of the water jets is 20 Bar to 600 Bar.

35. The method of claim 31, wherein pressure of the water jets is 100 Bar to 300 Bar.

36. The method of claim 31, wherein the needle shower comprises 1 to 50 nozzles.

37. The method of claim 31, wherein the needle shower comprises 1 to 20 nozzles.

38. The method of claim 31, wherein the needle shower comprises 1 to 10 nozzles.

39. The method of claim 22, further comprising blowing air onto the belt or through air drying fabric in a direction towards the vacuum box with an air knife while traversing the air knife across the width of the belt or through air drying fabric of the papermaking machine.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Exemplary embodiments of the present invention will be described with references to the accompanying figures, wherein:

[0018] FIG. 1 is a block diagram illustrating a conventional system and method for cleaning a structuring fabric;

[0019] FIG. 2 is a block diagram illustrating a system and method for cleaning of a structuring fabric according to an exemplary embodiment of the present invention;

[0020] FIG. 3 is a block diagram illustrating a system and method for cleaning of a structuring fabric according to an exemplary embodiment of the present invention;

[0021] FIG. 4 is a block diagram illustrating a conventional system and method for cleaning of a reel belt;

[0022] FIG. 5 is a block diagram illustrating a system and method for cleaning of a reel belt according to an exemplary embodiment of the present invention;

[0023] FIG. 6 is a block diagram illustrating a system and method for cleaning of a structuring fabric or reel belt with the use of a traversing air knife according to an exemplary embodiment of the present invention; and

[0024] FIG. 7 is a representative drawing showing a traversing shower and vacuum box according to an exemplary embodiment of the present invention operating on a belt of a through-air-drying papermaking machine.

DETAILED DESCRIPTION

[0025] A high pressure shower may be used to clean the sheet-contacting side (or the roll contacting side) of a structuring fabric of a TAD machine. In accordance with exemplary embodiments of the present invention, rather than a full width impact shower, a traversing higher pressure shower is utilized. This shower can also have an attached vacuum source to immediately vacuum off the loosened contamination. The vacuuming is preferably done on the same side as the showering. One suitable machine for cleaning fabrics or belts according to exemplary embodiments of the method of the present invention is an M-clean™ available from Kadant Solutions.

[0026] Embodiments of the present invention are applicable to belts used on through-air-drying papermaking machines. It should be appreciated that the term “belt” as used herein may refer to any type of belt used on a through-air-drying papermaking machines, including but not limited to structuring fabrics and reel belts. The following terms may be used interchangeably herein: “structuring belt”; “structured belt”; “structuring fabric”; “structured fabric”; “imprinting belt”; and “imprinting fabric”. These terms refer to an endless element or component with a structured or pattered surface used on a paper-machine to increase the bulk of the fibrous web by imprinting its surface pattern into the web. On tissue products the improvement in bulk can also lead to improvements in vital quality parameters such as absorbency and softness. A “reel belt” as used herein may be defined as a flexible, endless element or component used on a paper-machine to provide a nip point to a surface upon which a paper web is wound. The surface upon which the web is wound is typically referred to as a spool or shaft.

[0027] The preferred nozzle used to apply the high pressure water is a needle shower nozzle that ejects a round water jet with a diameter of from about 0.15 mm to about 0.55 mm, with a preferred diameter of 0.2 mm to 0.3 mm. The pressure of the water jet is from about 20 Bar to about 600 Bar, preferably 100 Bar to 300 Bar. The number of nozzles on the traversing head can range from 1 nozzle to 50 nozzles, more preferably 1 to 20 nozzles, and most preferably 1 to 10 nozzles. Fish tail nozzles may also be useful in exemplary embodiments of the present invention. Nozzles having spray angles of about 15 to 30 degrees, for example, 20 degrees, with openings of about 0.25 mm may be suitable. The nozzles may provide a hitting angle against the fabric of from about 20 to about 50 degrees, for example, about 40 degrees. The distance between nozzle tips and the fabric may be from about 2 mm to about 6 mm or about 3 mm to 4 mm. A range of flows may be from 2 to 20 liters per minute.

[0028] Due to the traversing nature of the shower, a controller is used to adjust the distance of the shower by one shower jet diameter per revolution of the structuring fabric for even fabric cleaning. The shower is preferably used near a roll where the fabric has a significant amount of wrap around the roll. The wrap may incorporate from about 30 to about 270 degrees around the circumference of the roll, for example between 90 to 220 degrees around the circumference of the roll, and as a further example between 110 to 180 degrees around the circumference of the roll. This fabric wrap allows for the utilization of a high efficiency vacuum box that is assisted by centripetal force to remove the loosened contamination. The optionally attached vacuum box has an inside surface composed of a ceramic material to prevent fabric wear resulting from contact with the structuring fabric. The vacuum box shape preferably matches the shape of the roll around which the fabric is wrapped to allow for intimate contact with the fabric. The box immediately removes the contamination using vacuum and is assisted by the centripetal force as the fabric moves along the circumference of the machine roll. The vacuum may provide flow of about 17 cubic meter/min at −0.3 Bar. If a flooding shower is utilized, the vacuum box may not be necessary as the loosened debris is flushed from the fabric by the flooding shower water and centripetal force around the roll. The water and vacuum piping to the high pressure shower and vacuum box is preferably flexible such that it can be compressed or folded as the shower traverses in the cross direction along the fabric.

[0029] The traversing shower and attached vacuum box can also be utilized to clean the inside (non-sheet contacting side) of the structuring fabric. A traversing higher pressure shower eliminates the need for a fixed full width impact shower which would otherwise use much more water and energy. Typically, a full width impact shower will use between 1.0 to 3.0 liter/min of water per inch width of the structuring fabric. When utilizing a traversing shower, the water use may be about 95% less than the full width impact shower, or about 0.05 to 0.15 liter/min per inch width of the structuring fabric. At 100 Bar, the water flow will be about 4.05 l/min. At 200 Bar, the water flow will be about 5.85 l/min. At 300 Bar, the water flow will be about 7.65 l/min. The energy associated with pumping water is roughly linear to the flow and thus up to 95% more energy efficient when using a traversing shower compared to the full width fixed impact shower.

[0030] In embodiments, a traversing high pressure shower and vacuum box may be used to clean the reel belts used on some TAD machines. When the paper web reaches the reel belt, the web has been fully dried; typically to about 97% consistency (3% water). Any contact with water on the reel belt or wet spot in the web would cause the web to stick to the belt and break rather than transfer from the belt and wind onto the finished paper roll, which is then converted into thousands of rolls intended for consumers in a separate process. Thus, in order to keep the reel belt clean from contaminants, full cross direction width showers cannot be utilized while the web is traveling along the belt. The conventional method to clean the fabric involves discontinuation of the paper-making process while a full width flooded nip shower is used to clean the reel belt. Once the belt has been cleaned, a full width air shower is used to dry the belt before resuming making paper.

[0031] With the inventive method, cleaning the reel belt is possible while continuing to make paper. In this regard, a traversing higher pressure needle shower along with an attached vacuum source is utilized on a roll with a high degree of wrap (i.e., there is a high degree of wrap of the reel belt around the roll) after the sheet has been transferred to the Yankee dryer while at the same time the endless looped reel belt returns to convey the paper web. This method increases productivity on the paper machine since no downtime is required to clean the reel belt.

[0032] In another exemplary embodiment, the traversing shower and vacuum header incorporates a traversing air knife. If the traversing shower is installed along a flat section of a fabric uninterrupted by a machine roll, then a traversing air knife can be placed on the same side of the fabric as that of the traversing vacuum header to aid in the removal of the applied shower water and released contaminants into the vacuum head. The width of the traversing air knife may match the width of the vacuum box and may move in synchronicity with the vacuum box through use of a positioning system.

[0033] According to an exemplary embodiment, the traversing shower and vacuum header may be used for spot cleaning of the structuring fabric or reel belt. The shower positioning system may position the shower directly over an area of the fabric or belt that has higher contamination compared to the remainder of the fabric. Once the fabric cleanliness is even, the positioning system can proceed with traversing the shower across the full width of the fabric or belt.

[0034] According to an exemplary embodiment of the present invention, a traversing high pressure shower and vacuum box is used to clean multi-layer TAD (structured tissue) fabrics. Examples of such fabrics are disclosed in U.S. Pat. Nos. 10,208,426; 10,415,185; 10,815,620; and 10,787,767, the contents of which are incorporated herein by reference in their entirety. The need to clean TAD fabrics without direct flow thru channels requires more targeted water and vacuum cleaning systems which the current invention provides. An advantage of the M-clean™ system is provided by the application of water against a turning roll or blocked back side of the fabric. This prevents the water from passing completely through the fabric which enables the vacuum system to remove the fiber/water mixture from the side the water is added. This is important to reduce the amount of fiber stapling into the inner zones of the multi-ply fabric since the “air” channels are not aligned in the Z directions and can become difficult to clean. Other types of fabrics which may benefit from the cleaning systems and methods in accordance with exemplary embodiments of the present invention include fabrics having structures as described in U.S. Pat. Nos. 10,099,425 and 10,675,810, the contents of which are also incorporated herein by reference in their entirety. These 3-D printed structures include multiple shapes and interfaces between layers which require improved cleaning that conventional methods cannot provide.

[0035] FIG. 1 is a block diagram illustrating a conventional system 1000 and method for cleaning a structuring fabric. As shown, typically a sheet side impact shower 1020 and non-sheet side impact shower 1030 are utilized with a non-sheet side flooding shower 1040. The impact showers 1020, 1030, 1040 extend across the full width of the fabric 1010. The paper web is transferred from a forming fabric to the structuring fabric at the 2.sup.nd transfer 1050 where it is then conveyed through one or more TAD drums 1060 which blow hot air through the web for drying. The web is transferred to the Yankee dryer (not shown) at the pressure roll 1070, at which point the endless looped structuring fabric 1010 is then cleaned and returned to the 2.sup.nd transfer to again convey the sheet through the TAD drums 1060 to the Yankee dryer.

[0036] FIG. 2 is a block diagram illustrating a system 1 and method for cleaning of a structuring fabric according to an exemplary embodiment of the present invention. As shown, the sheet side full width impact shower is replaced with a traversing needle shower 20 and optional attached vacuum box 30. The water and energy requirements for the traversing shower 20 are approximately 95% less than the full width impact shower. If a flooding shower 40 that flushes from the non-sheet side to sheet side of the fabric 10 is utilized in the nip between the roll and fabric 10 upon which the traversing shower 20 is located, than an attached vacuum box to the traversing shower may be unnecessary.

[0037] FIG. 3 is a block diagram illustrating a system 100 and method for cleaning of a structuring fabric according to an exemplary embodiment of the present invention. As shown, both the sheet side full width impact shower and the non-sheet side full width impact shower are replaced with respective traversing needle showers 120, 130 and optional vacuum boxes 140, 150. The water and energy requirements for the traversing shower 120, 130 are approximately 95% less than the full width impact shower. If a flooding shower 160 that flushes from the non-sheet side to sheet side of the fabric 110 is utilized in the nip between the roll and fabric 110 upon which the traversing shower 120, 130 is located, then an attached vacuum box to the traversing shower may be unnecessary.

[0038] FIG. 4 is a block diagram illustrating a conventional system 2000 and method for cleaning of a reel belt. As shown, a non-sheet side to sheet side flooding shower 2020 is used in the nip between the reel belt 2010 and a roll 2080 with a high degree of fabric wrap. The shower 2020 is operated only when the sheet/web is not being produced and thus contributes to lost productivity.

[0039] FIG. 5 is a block diagram illustrating a system 200 and method for cleaning of a reel belt according to an exemplary embodiment of the present invention. A shown, a traversing shower 220 and attached vacuum box 230 is used to clean the fabric 210 along a roll 280 with a high degree of fabric wrap after the sheet/web has been transferred to the building parent roll. The shower 220 can be run while the paper web is being conveyed since the vacuum box 230 is removing the contaminants and small volume of water from the traversing shower 220 with the aid of centripetal force before the reel belt 210 returns to conveying the web.

[0040] FIG. 6 is a block diagram illustrating a system 300 and method for cleaning of a structuring fabric or reel belt with the use of a traversing air knife according to an exemplary embodiment of the present invention. As shown, a traversing shower 320 and attached vacuum box 330 is used to clean the fabric 310 along a flat section of the fabric uninterrupted by a machine roll. A traversing air knife 340 can be placed on the opposing side of the fabric 310 to the traversing vacuum head 330 to aid in the removal of the applied shower water and released contaminants into the vacuum head 330.

[0041] FIG. 7 shows a traversing shower head, generally designated by reference number 400, and a vacuum box, generally designated by reference number 500, according to an exemplary embodiment of the present invention, operating on a belt 600, which may be, for example, a structuring fabric or reel belt. As shown, the shower head 400 has a width that is less than that of the belt 600. The shower head 400 reciprocates across the width of the belt 600 along a first rail or beam 410. The vacuum box 500 also reciprocates across the width of the belt 600 along a second rail or beam 510. Movement of the shower head 400 and the vacuum box 500 may be controlled such that they are positioned directly opposite one another as they traverse across the belt.

[0042] The shower head 400 and vacuum box 500 may be suspended from a carriage or rail. As the traversing range of the shower head 400 and vacuum box 500 may not be coextensive with the width of the fabric being cleaned, it may be useful to utilize multiple shower heads and vacuum boxes that are staggered, thereby enabling cleaning of the full width of the fabric. Each set of shower heads and vacuum boxes may be suspended from separate carriages.

[0043] For enhanced fabric cleaning and/or drying, the inventions taught in co-pending U.S. patent application Ser. Nos. 17/336,694 and 17/474,556, and U.S. Provisional Application Nos. 63/257,184, 63/287,139 and 63/270,113, which are hereby incorporated by reference in their entirety, may be combined with the present invention.

[0044] Now that embodiments of the present invention have been shown and described in detail, various modifications and improvements thereon can become readily apparent to those skilled in the art. Accordingly, the exemplary embodiments of the present invention, as set forth above, are intended to be illustrative, not limiting. The spirit and scope of the present invention is to be construed broadly.