Device and Method for Producing a Pulp Web

Abstract

The invention relates to a method and a device for drying a pulp web, with dewatering of the pulp web by pressing and the pulp web being guided directly on the press belt to a first transfer area for transfer of the pulp web to a transfer clothing and transfer of the pulp web in a second transfer area to a dryer. It is characterized in that the pulp web undergoes thermal drying between the first transfer area and the second transfer area. This enables production of a pulp web with improved quality characteristics and low energy consumption at the same time.

Claims

1-28. (canceled)

29. A method for producing a pulp web (1), especially a tissue or sanitary paper web, comprising dewatering the pulp web (1) by pressing the pulp web (1) in a first pressing area (2) between a first clothing (3) comprising a felt and a rotating press belt (4) with line loads between 80 kN/m and 600 kN/m; transferring the dewatered pulp web (1) to the rotating press belt (4) with the pulp web (1) being guided directly on the press belt (4) out from the first pressing area (2) to a first transfer area (5); transferring the pulp web (1) from the rotating press belt (4) to a transfer clothing (6) in the first transfer area (5); and transferring the pulp web (1) from the transfer clothing (6) to a drying cylinder (8) in a second transfer area (7); wherein the pulp web (1) is dried thermally between the first transfer area (5) and the second transfer area (7).

30. The method according to claim 29, wherein the pulp web (1) is structured in the first transfer area (5) by transferring the pulp web (1) from the rotating press belt (4) revolving at a higher speed to the transfer clothing (6) revolving at a lower speed, and wherein the transfer clothing (6) is a structured transfer clothing.

31. The method according to claim 29, wherein the thermal drying of the pulp web (1) on the transfer clothing (6) comprises convection drying of the pulp web (1), drying air being applied directly to the pulp web (1) by a drying device (9) and the drying air then being sucked back into the drying device (9).

32. The method according to claim 31, wherein the thermal drying of the pulp web (1) carried on the transfer clothing (6) further comprises through-air drying of the pulp web (1), wherein drying air is applied through the drying device (9) directly to the pulp web (1), a first part of the drying air being sucked back into the drying device (9) again and a second part of the drying air being sucked through the pulp web (1) into a suction device (10) with the transfer clothing (6) running between the pulp web (1) and the suction device (10).

33. The method according to claim 29, comprising applying drying air directly to the pulp web (1) between the first transfer area (5) and the second transfer area (7) for thermally drying the pulp web (1), wherein the temperature of the drying air is set by one or more of direct and indirect use of process waste heat produced during thermal drying of the pulp web (1) after one or both of the second transfer area (7) and sub-systems, particularly in a vacuum system.

34. A device for producing a pulp web (1), especially a tissue or sanitary paper web, comprising: a first clothing (3) and a rotating press belt (4) in a first pressing area (2) and configured for dewatering the pulp web (1) between the first clothing (3) and rotating press belt (4); a transfer clothing (6) configured for transferring the pulp web (1) from the rotating press belt (4) to the transfer clothing (6) in a first transfer area (5), wherein the pulp web (1) is guided directly on the rotating press belt (4) between the first pressing area (2) and the first transfer area (5); a drying cylinder (8) configured for transferring the pulp web (1) from the transfer clothing (6) to the drying cylinder (8) in a second transfer area (7); and a drying device (9) disposed in the an between the first transfer area (5) and the second transfer area (7) for thermally drying the pulp web (1).

35. The device according to claim 34, wherein the transfer clothing (6) is a structured transfer clothing (6) in the first transfer area (5), and wherein a speed of the structured transfer clothing (6) is slower than a circumferential speed of the rotating press belt (4) in the first transfer area (5).

36. The device according to claim 34, wherein the drying device (9) comprises a convection drying area (11) and drying air can be applied directly to the pulp web (1) by the drying device (9) and sucked back into the drying device (9) in the convection drying area (11).

37. The device according to claim 36, wherein the drying device (9) further comprises a through-air drying area (12) and a suction device (10) disposed opposite the drying device (9), wherein drying air is applied directly to the pulp web (1) by the drying device (9) and the suction device (10) sucks up at least a part of the drying air.

38. The device according to claim 37, comprising clothing stabilizing elements (13) in an area of the suction device (10), the clothing stabilizing elements (13) being disposed on a side of the suction device (10), wherein the transfer clothing (6) is guided between the drying device (9) and the clothing stabilizing elements (13).

39. The device according to claim 34, wherein the drying device (9) is connected directly or indirectly to a process waste heat duct, which thereby provides use of process waste heat produced during thermal drying of the pulp web (1) after one or both of the second transfer area (7) and sub-systems, especially a vacuum system.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The invention will now be described using the examples in the drawings.

[0018] FIG. 1 shows a machine for production of a pulp web according to the state of the art.

[0019] FIG. 2 shows an embodiment of a device for drying a pulp web.

DETAILED DESCRIPTION

[0020] FIG. 1 shows a device according to the state of the art for production of a pulp web 1, a pulp suspension being placed between two clothings via a headbox 14 and dewatered centrifugally. Here, the pulp suspension is placed between a first clothing 3—a felt—and a forming wire and dewatered. When a pulp web 1 has formed, the pulp web 1 is carried on the first clothing 3 to a first pressing area 2, where the pulp web 1 is pressed between the first clothing 3 and a rotating press belt 4. Here, the pulp web 1 is transferred to the rotating press belt 4 and carried directly on the press belt 4 out of the first pressing area 2 to a first transfer area 5, with transfer of the pulp web 1 in the first transfer area 5 from the rotating press belt 4 to a transfer clothing 6 followed by transfer of the pulp web 1 in a second transfer area 7 from the transfer clothing 6 to a drying cylinder 8. Drying of the pulp web 1 on the drying cylinder 8 is followed by reeling 15 of the pulp web 1.

[0021] FIG. 2 shows a plant for production of a pulp web 1 with the disclosed device for drying the pulp web 1. When a pulp web 1 has formed, the pulp web 1 is carried on the first clothing 3 to a first pressing area 2, where the pulp web 1 is pressed between the first clothing 3 and a rotating press belt 4. Here, the pulp web 1 is transferred to the rotating press belt 5 and carried directly on the press belt 4 out of the first pressing area 2, with transfer of the pulp web 1 in the first transfer area 5 from the rotating press belt 4 to a transfer clothing 6. Advantageously, the pulp web 1 is structured in the first transfer area 5, where structuring of the pulp web 1 takes place by transferring the pulp web 1 from the rotating press belt 4, revolving at a higher speed, to the transfer clothing 6, revolving at a lower speed, and the transfer clothing 6 being designed as a structured transfer clothing. According to the invention, thermal drying is applied after the first transfer area 5 and before a second transfer area 7, in which the pulp web 1 is transferred from the transfer clothing 6 to a drying cylinder 8. For thermal drying, drying air is applied by a drying device 9 directly to the pulp web 1. The drying device 9 also has a convection drying area 11. In the convection drying area 11, the drying air is applied directly to the pulp web 1 and sucked back into the drying device 9 again. The drying device 9 also has a through-air drying area 12, the drying air being applied directly to the pulp web 1 by the drying device 9, a first part of the drying air being sucked back into the drying device 9 after drying and a second part of the drying air being sucked through the pulp web into a suction device 10. Advantageously, clothing stabilizing elements 13 are provided in the area of the suction device 10. The clothing stabilizing elements 13 comprise guide rolls, where design as a suction roll 17 is also possible. The drying air is used directly and/or indirectly from process exhaust air. In this way, the exhaust air from the high-temperature drying hood 18, for example, can be used as a supply air drying device 19.

[0022] The present invention thus offers numerous advantages. It enables production of a pulp web with improved quality characteristics and with low energy consumption and thus low operating costs at the same time. Similarly, low capital expenditure is possible because the dryer for thermal drying of the pulp web can have a smaller design after the second transfer area.

REFERENCE NUMERALS

[0023] (1) Pulp web [0024] (2) First pressing area [0025] (3) First clothing [0026] (4) Rotating press belt [0027] (5) First transfer area [0028] (6) Transfer clothing [0029] (7) Second transfer area [0030] (8) Drying cylinder [0031] (9) Drying device [0032] (10) Suction device [0033] (11) Convection drying area [0034] (12) Through-air drying area [0035] (13) Clothing stabilizing element [0036] (14) Headbox [0037] (15) Reel [0038] (16) High-temperature drying hood [0039] (17) Clothing stabilizing element designed as a suction roll [0040] (18) Exhaust air from high-temperature drying hood [0041] (19) Supply air drying device