Drying section for producing kraft paper

Abstract

The invention relates to a drying section, in particular a post-drying section (20), for drying a fibrous web, for an installation for producing kraft paper, wherein the drying section has a contact drying region (70) which is provided upstream of an impact drying region (71) in the machine running direction (1), and at least two, in particular three, drying cylinders (72) arranged one after the other in the machine running direction (1) are provided in the contact drying region (70). The drying section is characterized in that a separate and endlessly circulating drying screen (73) is provided for each drying cylinder (72), said drying screen following the outer circumference of the respective drying cylinder (72) in a pressing region (74). The invention additionally relates to an installation, to a method, and to a use.

Description

[0001] Drying section for the production of kraft paper

[0002] The present invention relates to a dryer section for producing kraft paper as well as a kraft paper production plant, a method and a use according to the independent patent claims.

[0003] Processes for producing kraft paper are known in the art. Kraft paper is a special type of paper characterized, among other things, by its particularly high strength. Due to this property, it is used for various packaging applications, such as the production of paper bags. In addition to strength, other parameters are also important, depending on the specific application of the kraft paper, such as stretchability or air permeability.

[0004] The properties of paper depend significantly on the conditions during its production. One object of the present invention can therefore be seen as providing a method and a device that can produce kraft paper with an improved property profile compared to the prior art.

[0005] A critical step in the production of kraft paper is the drying of the fiber web, as a drastic increase in the dry content of the material must be achieved during the papermaking process. While the initial fiber suspension usually has a dry content of less than 1%, the dry content of the finished paper web is typically at least 85%. The drying processes that take place here have a significant influence on the extensibility properties of the resulting paper.

[0006] Dewatering or drying takes place in various process steps and plant components. After initial dewatering of the fiber suspension in a wire section, the resulting fiber web is dried by thermally removing the water by heating the fiber web.

[0007] For this purpose, it is known that the fibrous web is guided over so-called drying cylinders, which are heated, in particular, from the inside. This results in what is known as contact drying. To facilitate better heat transfer from the surface of a drying cylinder to the fibrous web, endlessly guided belts or bands (also known as drying wires) can be provided, which press the fibrous web against the outer circumference of the drying cylinder.

[0008] It is also possible to apply hot air to the fibrous web via so-called drying hoods, thereby creating what is known as impact drying. Here, too, the fibrous web runs over drying cylinders, which are generally internally heated. Typically, in this case, a drying hood is assigned to one or more drying cylinders. Unlike contact drying, there is no pressing of the fibrous web by belts or tapes.

[0009] An important aspect of drying the fibrous web is maintaining or generating a tensile stress on the fibrous web in the machine direction in order to enable controlled travel of the fibrous web and to be able to control the extensibility properties of the paper in the machine direction. Since prior art systems have certain problems in this regard, one object of the invention can be seen in improving the tension build-up in the drying section of such a system. Typically, a plant for producing kraft paper comprises several drying devices arranged one after the other (e.g., contact drying cylinders or impact drying hoods), with the entirety of the drying devices being referred to as the drying section.

[0010] The dryer section can be divided into several sections, with different sections in the machine direction usually being separated by another device for processing the fibrous web. A typical example in which several dryer section sections are provided is a plant used in particular for the production of sack kraft paper. According to the prior art, a first dryer section section, referred to as the pre-dryer section, is provided, followed by an edger for edgering the fibrous web. After passing through the edger, the fibrous web is led into a second dryer section section, referred to as the post-dryer section. If the edger is not used in such a plant, the fibrous web can be led past the edger through a bypass device in which essentially no treatment of the fibrous web takes place.Even then, there is a division into pre-drying section and post-drying section.

[0011] Dryer section sections, which are used in particular as after-dryer sections, which are arranged in the machine direction after an upsetting device, can have a contact drying section and an impact drying section, whereby the impact drying section usually follows directly after the contract drying section.

[0012] It is known that the contact drying area comprises several (e.g., three) drying cylinders over which the fibrous web is guided. A drying wire is provided that presses the fibrous web against the outer periphery of the drying cylinders. A drying wire can be assigned to several drying cylinders.

[0013] The inventors have now observed that such an arrangement is disadvantageous with regard to the reliable control of the tension buildup on the fibrous web. A specific object of the present invention can therefore be seen in improving the tension buildup on the fibrous web in such a dryer section and, in particular, in enabling wrinkle-free travel of the fibrous web in the subsequent impact drying area.

[0014] The present invention therefore relates in particular to a drying section, which preferably forms a post-drying section of a plant for producing kraft paper, wherein the drying section comprises a contact drying area with contact drying cylinders and an impact drying area with impact drying devices arranged in the machine direction, in particular directly after the contact drying area.

[0015] Completely unexpectedly and surprisingly, it was discovered that the problems described above with regard to the tension build-up can be overcome in particular by assigning each drying cylinder of the contact drying area its own or separate drying wire.

[0016] This enables improved adjustment of the desired tension build-up on the fibrous web in the machine direction, which ultimately allows improved control of the extensibility properties of the produced kraft paper.

[0017] Each dryer fabric follows the outer circumference of the respective drying cylinder in a contact zone, with the contact zone comprising a certain portion of the outer circumference of the drying cylinder. The longer the length of the contact zone, the longer the contact time of the fibrous web with each individual drying cylinder and the greater the drying effect.

[0018] In order to vary the contact pressure with which the fibrous web is pressed against the drying cylinder via the dryer fabric, at least one of the guide rollers used to guide the dryer fabrics can be designed as a movable tension roller. This tension roller is arranged in such a way that the tension exerted on the dryer fabric changes with its displacement. Typically, each drying cylinder in the contact drying section has a separately controllable drive. This enables the drying cylinders to be set to different rotation speeds, which can offer further advantages in terms of tension build-up. For example, it is possible for the rotation speed of successive drying cylinders to increase continuously, which is not possible in dryer sections with only one dryer fabric and without separately controllable drives.

[0019] The drying screens typically do not have their own drives, but are driven via the drying cylinders.

[0020] The drying cylinders can be heated separately, with heating from the inside. For this purpose, the drying cylinders are equipped with a steam supply channel through which saturated steam (water) can be introduced. The steam pressure can be up to 12 bar, for example.

[0021] In the contact drying area, at least two, preferably three, drying cylinders and a corresponding number of drying wires are provided. The drying cylinders of the contact drying area are arranged directly one after the other, meaning that no other drying devices, i.e., devices that exert a significant drying effect on the fibrous web, are provided between them.

[0022] A so-called draw zone can be provided between the drying cylinders of the contact drying section. In this draw zone, the fibrous web experiences, in particular, free draw. This means that the fibrous web is not in contact with any equipment along this draw zone, in particular neither with a drying cylinder nor with a drying wire.

[0023] The length of a draw section can, in particular, be the distance traveled by the fibrous web between the end of one pressing zone and the beginning of a subsequent pressing zone. The contact drying zone is typically directly followed by the impact drying zone, which comprises several drying hoods and associated cylindrical rollers, collectively referred to as impact drying devices. Here, the thermal energy for drying the fibrous web is introduced not only via the contact side between the roller and the fibrous web, but also via the exposed surface of the fibrous web by blowing hot gas, especially air.

[0024] In the impact drying area, several, in particular three, groups of impact drying devices can be provided, with each group optionally comprising two impact drying devices. In each impact drying device, a cylindrical roller is assigned to a hood, over whose outer circumference the fibrous web is guided. Between two impact drying devices, additional drying rollers can be provided, which are internally heated, similar to the drying rollers in the contact drying area.

[0025] Furthermore, additional drying rollers can be provided between two groups of impact drying devices, which are heated from the inside, similar to the drying rollers from the contact drying area, and are optionally designed with a drying screen.

[0026] The transition between the contact drying area and the impact drying area is formed, in particular, by the first impact drying device in the machine direction. The drying cylinder located immediately upstream of this impact drying device typically forms the last drying cylinder in the contact drying area.

[0027] As already mentioned, the dryer section described here is, in particular, the after-drying section of a kraft paper production plant. However, it is also possible to use this dryer section in another area of ​​the plant. In general, the dryer section is therefore part of the dryer section of a kraft paper production plant, or the dryer section forms the dryer section of such a plant. The fibrous web fed into this dryer section typically has a dry content of at least 55%, in particular of at least 65%. However, the dry content is usually below 75%, in particular below 70%.

[0028] After passing through the drying section, the fibrous web can have a dry content of up to 85%, and possibly up to 95%.

[0029] Typically, the rotation speed of the drying rollers, in particular at least the first drying roller, in the contact drying section is higher than the speed of the fibrous web entering the contact drying section. This creates tension on the incoming fibrous web.

[0030] Successive drying rollers in the contact drying section can have different, particularly continuously increasing, rotation speeds. However, the subsequent drying rollers can also have the same rotation speed.

[0031] If necessary, the rotation speed of the drying rollers of the contact drying area is lower than the rotation speed of the cylinder roller of the first impact drying device of the impact drying area.

[0032] If necessary, the drying rollers of the impact drying section can also be heated. Typically, these drying rollers are not assigned a drying fabric. Heating can be achieved with steam, similar to the drying rollers in the contact drying section. A steam pressure of up to 12 bar can be provided, which is preferably between 0.5 and 8 bar. This is advantageous because the heating causes the formation of a steam layer and reduces friction between the fibrous web and the roller surface. This can potentially lead to better (i.e., more homogeneous) transverse shrinkage of the fibrous web.

[0033] The invention relates, where appropriate, to a drying section, in particular an after-drying section, for drying a fibrous web, for a plant for producing kraft paper, wherein the drying section has a contact drying area arranged in the machine direction upstream of an impact drying area, wherein at least two, in particular three, drying cylinders arranged one after the other in the machine direction are provided in the contact drying area.

[0034] It is preferably provided that a separate and endlessly rotating drying screen is provided for each drying cylinder, which follows the outer circumference of the respective drying cylinder in a contact area.

[0035] If necessary, it is provided that a drawing section is provided between the drying cylinders, in particular between two drying cylinders arranged directly one after the other in the machine direction, in which the fibrous web is exposed.

[0036] Where appropriate, it is provided that the fibrous web along the drawing path is not in contact with the outer circumference of a drying cylinder and / or with a drying wire

[0037] Optionally, it is provided that the length of the pulling section between two drying cylinders arranged directly one after the other in the machine direction is at least 0.5 m, in particular at least 1.0 m, preferably between 1.0 m and 2.0 m.

[0038] Where appropriate, the wrap angle of the drying fabric in the contact area on the respective drying cylinder is at least 100°, in particular at least 140°.

[0039] Optionally, it is provided that each drying cylinder of the contact drying area is provided with its own drive device, wherein the drive devices are in particular separately controllable and / or adjustable, and / or that each drying cylinder of the contact drying area is provided with its own heating device, wherein the heating devices are in particular separately controllable and / or adjustable. Optionally, it is provided that the drying cylinders are arranged directly one after the other in the machine direction.

[0040] If necessary, it is provided that the drying screens are guided over guide rollers, wherein at least one of the guide rollers is designed as a spatially displaceable tension roller.

[0041] If necessary, a drying screen is provided to press the fibrous web in the contact area against the outer circumference of the respective drying cylinder.

[0042] Optionally, the invention also relates to a plant for producing kraft paper comprising the following plant components:

[0043] - a wire section for forming a fibrous web by continuously applying a fibrous suspension along the machine direction through a headbox,

[0044] - a shaking device for shaking the fibrous web transversely to the machine direction, i.e. in the transverse direction,

[0045] - a press section for pressing the fibrous web partially dewatered in the wire section,

[0046] - a drying section for drying the fibrous web,

[0047] - a winding station for winding up the paper web formed from the fibrous web.

[0048] It is preferably provided that the drying section comprises a drying section with one or more of the features described here, in particular a drying section according to the invention.

[0049] Optionally, it is provided that the drying section comprises a pre-drying section and an after-drying section, and that the after-drying section of the system is a drying section with one or more of the features described here, in particular a drying section according to the invention. Optionally, it is provided that an upsetting device, in particular a Clupak device, is arranged between the pre-drying section and the after-drying section.

[0050] Optionally, it is provided that the width of the drying fabrics is smaller than the width of the fibrous web, wherein the width of the drying fabrics is in particular at least 1 m, preferably at least 2 m, smaller than the width of the fibrous web.

[0051] Optionally, the invention relates to a process for producing kraft paper comprising the following steps:

[0052] - Forming a fibrous web running along the machine direction by continuously applying a fibrous suspension to a wire section through a headbox,

[0053] - Shaking the fibrous web transversely to the machine direction, i.e. in the transverse direction, by a shaking device,

[0054] - Pressing the fibrous web, previously partially dewatered in the wire section, in a press section,

[0055] - further drying of the fibrous web in a drying section,

[0056] - Winding up the paper web formed from the fibrous web in a winding station, wherein the drying section comprises a drying section section having a contact drying area arranged in the machine direction upstream of an impact drying area, wherein at least two, in particular three, drying cylinders arranged one after the other in the machine direction are provided in the contact drying area.

[0057] It is preferably provided that a separate and endlessly rotating drying wire is provided for each drying cylinder, which follows the outer circumference of the respective drying cylinder in a contact area, and that the drying wire presses the fibrous web against the outer circumference of the drying cylinder.

[0058] Optionally, it is provided that drying takes place in a pre-drying section and in a post-drying section, and that the drying section is arranged in the post-drying section or forms the post-drying section. Optionally, it is provided that the fibrous web has a dry content of at least 55 wt.%, in particular of at least 65 wt.%, upon entering the drying section and / or that the fibrous web has a dry content of at most 95 wt.%, in particular of at most 85 wt.%, upon exiting the drying section.

[0059] If necessary, it is provided that the rotation speed of the first drying cylinder in the machine direction of the contact drying area is lower, in particular up to 7% lower, than the movement speed of the fibrous web entering the drying section.

[0060] Optionally, it is provided that the rotational speed of the second drying cylinder in the machine direction of the contact drying area is greater, in particular by up to 0.15% greater, than the movement speed of the fibrous web between the first and second drying cylinders, and / or that the rotational speed of the third drying cylinder in the machine direction of the contact drying area is greater, in particular by up to 0.10% greater, than the movement speed of the fibrous web between the second and third drying cylinders.

[0061] Where appropriate, it is provided that the rotational speed of the cylindrical roller of an impact drying device of the impact drying area directly following the contact drying area is greater than or equal to the movement speed of the fibrous web leaving the contact drying area, wherein the speed difference is in particular between 0% and 0.10%.

[0062] Optionally, the invention also relates to the use of a dryer section having one or more of the features described here, in particular a dryer section according to the invention, in a process for producing kraft paper, preferably in a process having one or more of the features described here, in particular in a process according to the invention. Further features of the invention emerge from the patent claims, the figures, and the description of the exemplary embodiment.

[0063] The present invention is explained in detail below using an exemplary embodiment.

[0064] They show:

[0065] Fig. 1a-c is a schematic overall view of a kraft paper manufacturing plant according to a first embodiment of the invention; and

[0066] Fig. 2 is a schematic detailed view of a dryer section according to the invention according to a second embodiment of the invention.

[0067] Unless otherwise indicated, the following features are shown in the figures: Machine direction 1, wire section 2, headbox 3, jogging device 4, press section 5, dryer section 6, reeling station 7, dewatering wire 8, pre-dryer section 19, after-dryer section 20, upsetting device 21, calendering device 22, paper reel 25, contact drying area 70, impact drying area 71, drying cylinder 72, dryer wire 73, pressing area 74, guide roller 75, tensioning roller 76, impact drying device 77, drying hood 78, cylinder roller 79, further drying cylinder 80, fibrous web 81, displacement direction 82.

[0068] Fig. 1a-c show a schematic overall view of a kraft paper production plant according to a first embodiment of the invention. The plant comprises, in the machine direction 1, a headbox 3, a wire section 2, a press section 5, a pre-dryer section 19, an upsetting device 21, an after-dryer section 20, a calendering device 22, and a winding station 7. The calendering device 22 can alternatively be designed as an embossing device.

[0069] The headbox 3 serves, in a known manner, to apply a fiber suspension to the continuously rotating dewatering wire 8 of the wire section 2, thereby forming a fiber web. As the system progresses, the fiber web is continuously dewatered or dried, passing successively through the aforementioned system components. Finally, paper rolls 25 are formed, which can be transported away and / or fed to further processing steps.

[0070] The production speed of the system in this exemplary embodiment is approximately 1100 m / min. The resulting paper web has a paper width of approximately 6.4 m.

[0071] The function of the individual plant components is sufficiently known to a specialist in the field of paper production and will not be explained in detail here. The inventive features of the plant relate in particular to the after-drying section 20.

[0072] Fig. 2 shows an enlarged view of a dryer section according to a second embodiment of the invention in detail. The dryer section according to this embodiment can be used in the plant shown in Fig. 1 to produce kraft paper.

[0073] The dryer section shown here comprises a contact drying area 70, followed by an impact drying area 71. The contact drying area 70 contains three steam-heated drying cylinders 72, over which the incoming fiber web 81 is guided. The drying cylinders 72 are arranged directly one after the other.

[0074] A separate drive (not shown) is provided for each drying cylinder 72. Furthermore, each drying cylinder 72 is provided with its own drying wire 73, which is designed as a belt that presses the fibrous web 81 against the outer circumference of the respective drying cylinder 72 in a contact area 74.

[0075] Between successive pressing areas 74, pulling sections are provided in which the fibrous web 81 experiences a free pull.

[0076] Each dryer fabric 73 is guided in a continuous, circular motion over a series of guide rollers 75. Each of the guide rollers 75 is movable along a displacement direction 82 and thus serves as a tensioning roller 76 to adjust the tension of the dryer fabric 73 and thus the pressure with which the fibrous web 81 is pressed against the outer circumference of the drying cylinder 72.

[0077] Viewed in the machine direction, the contact drying area 70 is followed by the impact drying area 71. Only the beginning of the impact drying area 71 is shown in Fig. 2. This begins with an impact drying group comprising two impact drying devices 77. Each impact drying device 77 in turn comprises a drying hood 78 and a cylindrical roller 79. The fibrous web 81, which passes through an impact drying device 77, is deflected via the cylindrical roller 79 and blown with hot air by the drying hood 78, thereby subjecting it to drying.

[0078] Between the two impact drying devices 77, a further drying cylinder 80 is provided, which has a drive but no drying screen. This further drying cylinder 80 does not form part of the contact drying area 70 according to the invention, since it is arranged downstream of the first impact drying device 77, as seen in the machine direction 1.

[0079] The drying section according to this embodiment comprises two further impact drying groups, as described above.

[0080] A representation showing a complete drying section according to the invention, also used as a post-drying section 20, is Fig. 1 b and c.

[0081] Here, it can be seen that the fibrous web is fed directly from the compression device 21 into the after-drying section 20, which begins with a sequence of three drying cylinders 72 with separate drying wires 73. These three drying cylinders 72 form the contact drying area 70 of the after-drying section 20 according to the invention.

[0082] The contact drying area 70 is followed by the impact drying area 71, which begins with a group of two impact drying devices 77 separated by another drying cylinder 80. Three such groups are provided, with another drying cylinder 80 provided between each two groups, each equipped with another drying screen 7-14. The other drying cylinders 80 are not part of the contact drying area 70.

[0083] In terms of detailed structure and function, the dryer section shown in Fig. 1 is similar to that shown in Fig. 2.

[0084] In one embodiment of a method according to the invention, the fibrous web emerging from the compression device 21 has a dry content of approximately 65% ​​and is introduced into a post-drying section 20 designed according to the invention.

[0085] The rotation speed of the first drying cylinder 72 of the contact drying section 70 is lower than the speed of the incoming fibrous web. The rotation speed of the second and third drying cylinders 72 in the machine direction is each higher than the speed of the fibrous web upstream of the respective drying cylinder 72, so that tension builds up.

[0086] The speed differences can be adjusted as required, but this generally results in a gentle tension build-up up to the impact drying area 71 and an improvement in the transverse shrinkage profile of the fibrous web.

[0087] The adjustment of the speed differences is made possible in particular by the separate drives of the different drying cylinders 72.

[0088] In order to enable a crease-free travel of the fibrous web, the rotation speed of the first cylinder roller 79 of the impact drying area 71 is greater than the movement speed of the fibrous web leaving the contact drying area 70.

[0089] The width of the drying screens 73 is approximately 2 m smaller than the width of the fibrous web, whereby both edge regions of the fibrous web, each with a width of approximately 1 m, are not pressed by the drying screens 73 against the surface of the drying rollers 72. This further improves the cross-sectional profile of the produced paper web.

[0090] The resulting kraft paper exhibits a variety of advantageous properties. The kraft paper produced according to the described embodiment has the following exemplary property profile:

[0091]

[0092] 'measured in an area ±5 cm from the geometric center of the paper web in its transverse direction

[0093] “measured in an area not exceeding 10 cm from the edge of the paper web in its transverse direction

Claims

Patent claims 1. Drying section, in particular after-drying section (20), for drying a fibrous web, for a plant for producing kraft paper, wherein the drying section has a contact drying area (70) which is arranged in the machine direction (1) upstream of an impact drying area (71), wherein at least two, in particular three, drying cylinders (72) arranged one after the other in the machine direction (1) are provided in the contact drying area (70), characterized in that a separate and continuously rotating drying wire (73) is provided for each drying cylinder (72), which follows the outer circumference of the respective drying cylinder (72) in a contact region (74).

2. Drying section according to claim 1, characterized in that between the drying cylinders (72), in particular between two drying cylinders (72) arranged directly one after the other in the machine direction (1), a pulling section is provided in which the fibrous web is exposed.

3. Drying section according to claim 2, characterized in that the fibrous web along the drawing section is not in contact with the outer circumference of a drying cylinder (72) and / or with a drying wire (73) 4. Drying section according to claim 2 or 3, characterized in that the length of the pulling path between two drying cylinders (72) arranged directly one after the other in the machine direction (1) is at least 0.5 m, in particular at least 1.0 m, preferably between 1.0 m and 2.0 m.

5. Drying section according to one of claims 1 to 4, characterized in that the wrap angle of the drying wire (73) in the contact pressure area (74) on the respective drying cylinder (72) is at least 100°, in particular at least 140°.

6. Drying section according to one of claims 1 to 5, characterized in that for each drying cylinder (72) of the contact drying area (70) a separate drive device is provided, wherein the drive devices are in particular separately controllable and / or regulatable, and / or that a separate heating device is provided for each drying cylinder (72) of the contact drying area (70), wherein the heating devices are in particular separately controllable and / or regulatable.

7. Drying section according to one of claims 1 to 6, characterized in that the drying cylinders (72) are arranged directly one after the other in the machine direction (1).

8. Drying section according to one of claims 1 to 7, characterized in that the drying screens (73) are guided over guide rollers (75), wherein at least one of the guide rollers (75) is designed as a spatially displaceable tensioning roller (76).

9. Drying section according to one of claims 1 to 8, characterized in that a drying screen (73) presses the fibrous web in the contact area against the outer circumference of the respective drying cylinder (72).

10. Dryer section according to one of claims 1 to 9, characterized in that the width of the dryer fabrics (73) is smaller than the width of the fibrous web, wherein the width of the dryer fabrics (73) is in particular at least 1 m, preferably at least 2 m, smaller than the width of the fibrous web.

11. Plant for the production of kraft paper comprising the following plant components: - a wire section (2) for forming a fibrous web by continuously applying a fibrous suspension along the machine direction (1) through a headbox (3), - a shaking device (4) for shaking the fibrous web transversely to the machine running direction (1 ), i.e. in the transverse direction, - a press section (5) for pressing the fibrous web partially dewatered in the wire section (2), - a drying section (6) for drying the fibrous web, - a winding station (7) for winding the paper web formed from the fibrous web, characterized in that the drying section (6) comprises a drying section according to one of claims 1 to 10.

12. Plant according to claim 11, characterized in that the drying section (6) comprises a pre-drying section (19) and a post-drying section (20), and that the post-drying section (20) of the plant is a drying section according to one of claims 1 to 9.

13. Plant according to claim 12, characterized in that an upsetting device (21), in particular a Clupak device, is arranged between the pre-drying section (19) and the after-drying section (20).

14. A process for producing kraft paper comprising the following steps: - forming a fibrous web running along the machine direction (1) by continuously applying a fibrous suspension to a wire section (2) through a headbox (3), - shaking the fibrous web transversely to the machine direction, i.e. in the transverse direction, by a shaking device (4), - pressing the fibrous web previously partially dewatered in the wire section (2) in a press section (5), - further drying of the fibrous web in a drying section (6), - Winding up the paper web formed from the fibrous web in a winding station (7), wherein the drying section (6) comprises a drying section section having a contact drying area (70) which is arranged in the machine direction (1) upstream of an impact drying area (71), wherein in the contact drying area (70) at least two, in particular three, drying cylinders (72) arranged one after the other in the machine direction (1) are provided, characterized in that - that a separate and endlessly rotating drying screen (73) is provided for each drying cylinder (72), which follows the outer circumference of the respective drying cylinder (72) in a contact area (74), and - that the drying screen (73) presses the fibrous web against the outer circumference of the drying cylinder (72).

15. The method according to claim 14, characterized in that the fibrous web passes through a drawing section between the drying cylinders (72), in particular between two drying cylinders (72) arranged directly one after the other in the machine direction (1), and is exposed along the drawing section.

16. Method according to claim 15, characterized in that the fibrous web is not in contact with the outer circumference of a drying cylinder (72) and / or with a drying wire (73) along the drawing section.

17. The method according to claim 15 or 16, characterized in that the length of the pulling section between two drying cylinders (72) arranged directly one after the other in the machine direction (1) is at least 0.5 m, in particular at least 1.0 m, preferably between 1.0 m and 2.0 m.

18. Method according to one of claims 14 to 17, characterized in that the drying takes place in a pre-drying section (19) and in a post-drying section (20), and that the drying section is arranged in the post-drying section (20) or forms the post-drying section (20).

19. Method according to one of claims 14 to 18, characterized in that the fibrous web has a dry content of at least 55 wt.%, in particular of at least 65 wt.%, upon entering the drying section and / or that the fibrous web has a dry content of at most 95 wt.%, in particular of at most 85 wt.%, upon leaving the drying section.

20. Method according to one of claims 14 to 19, characterized in that the rotational speed of the first drying cylinder (72) in the machine direction of the contact drying area (70) is lower, in particular up to 7% lower, than the movement speed of the fibrous web entering the drying section. 21 . Method according to one of claims 14 to 20, characterized in that the rotational speed of the second drying cylinder (72) in the machine direction of the contact drying area (70) is greater, in particular by up to 0.15% greater, than the movement speed of the fibrous web between the first and second drying cylinders (72), and / or that the rotational speed of the third drying cylinder (72) in the machine direction of the contact drying area (70) is greater, in particular by up to 0.10% greater, than the movement speed of the fibrous web between the second and third drying cylinders (72).

22. Method according to one of claims 14 to 21, characterized in that the rotational speed of the cylinder roller of an impact drying device (77) of the impact drying area (71) directly following the contact drying area (70) is greater than or equal to the movement speed of the fibrous web leaving the contact drying area (70), the speed difference being in particular between 0% and 0.10%.

23. Use of a dryer section according to one of claims 1 to 10 in a process for producing kraft paper, in particular in a process according to one of claims 14 to 22.

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