Compacting device, and installation and method for producing kraft paper

Abstract

The invention relates to a method and a compacting device (21), in particular a Clupak device, for compacting a fibrous web in an installation for producing kraft paper, wherein a circulating cloth (26), a pressing bar (33), a wrap-around roller (34), a counter roller (28) and preferably a cloth drive roller (31) are provided. The compacting device (21) has a compacting mode, in which the circulating cloth (26) is pressed by the pressing bar (33) in the direction of the counter roller (28) and in which the cloth (26) wraps around the counter roller (28) by a wrap-around angle (35). In the compacting mode, a compacting gap (30) is formed between the cloth (26) and the counter roller (28), said compacting gap being designed such that the fibrous web is conveyed through the compacting gap at a production speed and is thereby compacted in the machine running direction (1), and an adjusting device (39) is provided for displacing the wrap-around roller (34) and thereby setting the wrap-around angle (35).

Description

[0001] Upsetting device and plant and process for the production of kraft paper

[0002] The invention relates to a compression device, a system, a method and a kraft paper according to the features of the independent patent claims.

[0003] Various 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] When it comes to the extensibility of kraft paper, a distinction is generally made between extensibility in the machine direction and extensibility across the machine direction, i.e., in the cross direction. To influence extensibility in the machine direction, it is known to use a compression device that compresses the fibrous web running through the production line in the machine direction. A widely used device for continuously compressing a fibrous web in the machine direction is a so-called "Clupak device." With this type of compression device, the fibrous web is conveyed through a compression gap. This compression gap is defined on one side by a compression belt called the "cloth" and on the other side by a drive roller. The cloth is usually an endlessly rotating belt made of an elastic material, which is pressed against the drive roller by a pressure bar in the area of ​​the compression gap.The pressure bar compresses the elastic fabric between the counterroller and the pressure bar, locally reducing its thickness. After passing the pressure bar, the fabric expands again, which, due to a transverse contraction effect, leads to a local slowing of the fabric. The fibrous web rests against the fabric in this area, causing it to be compressed in the machine direction during the described slowing of the fabric. The effect and structure of such compression devices are described in detail in the prior art. This effect is also utilized in the present invention.

[0005] The compression of the fiber web has a direct influence on the extensibility of the finished kraft paper in the machine direction. This extensibility is an important material parameter, making precise adherence to the specifications a key factor for the quality of the produced paper. For this reason, the design and basic settings during commissioning and during and after maintenance are of great importance. Therefore, conventional compression devices are preferably operated as consistently as possible without modification. However, this is a problem if a different kraft paper, for example, with a different grammage or a different extensibility in the machine direction, is to be produced on the system.

[0006] Another disadvantage of known edging devices of the above-mentioned type is their relatively high maintenance requirements. For example, slippage in the area of ​​the pressure beam and also in the area of ​​the counter roll creates high frictional forces on the cloth. These frictional forces and the relative movement cause significant wear. In practice, this results in the cloth having to be serviced or replaced frequently. Since paper cannot be produced with the desired parameters during maintenance and adjustment, servicing the edging device reduces the efficiency of the system. For this reason, attempts are being made to make the components of the edging device and the cloth more robust in order to extend maintenance intervals and thus improve the efficiency of the overall system.

[0007] The object of the present invention is to improve the efficiency of a plant for producing kraft paper. However, in contrast to the prior art, this object is achieved using a fundamentally different approach.

[0008] The problem is solved in particular by the features of the independent patent claims.

[0009] This compression device features an adjustment feature instead of the conventional rigid, unchangeable configuration. This adjustment feature allows for flexible adjustment of the compression. The design allows for rapid adjustment of the compression device, thereby improving the efficiency of the plant. Furthermore, the adjustability enables the production of kraft paper with different material parameters. This makes the plant more profitable and thus more efficient from an economic perspective.

[0010] In particular, the invention relates to a compression device, optionally a Clupak device, and / or a method for compressing a fibrous web of a plant for producing kraft paper.

[0011] Preferably, a circulating cloth, a pressure bar, a wrap-around roller, a counter roller and preferably a cloth drive roller are provided.

[0012] The compression device preferably has a compression mode in which the circulating fabric is pressed toward the counter roll by the pressure bar, and in which the fabric wraps around the counter roll at a certain wrap angle. In the compression mode, a compression gap is preferably formed between the fabric and the counter roll, which gap is configured to convey the fibrous web through at production speed and thereby compress it in the machine direction.

[0013] Preferably, an adjusting device is provided for displacing the wrap roller and thereby for changing and adjusting the wrap angle.

[0014] By changing the wrap angle, the compression of the fibrous web can be adjusted flexibly and precisely, in particular controlled and / or regulated.

[0015] If necessary, the adjusting device is designed such that the wrap angle can be adjusted by at least 10°, in particular by at least 20°, in particular by at least 25°, in particular by at least 40° or in particular by at least 60°.

[0016] If necessary, the adjustment device is designed such that the wrap angle of the cloth can be adjusted between 15° and 90°, preferably between 20°-60°, optionally between 25° and 55°.

[0017] If necessary, a compensating roller which can be displaced along a compensating path is provided to compensate for the displacement of the wrap-around roller while maintaining an essentially constant cloth length.

[0018] If necessary, the compensating roller has a freedom of movement or a stroke of more than 10 cm, in particular more than 20 cm, in particular more than 45 cm and preferably between 5 cm and 55 cm along the compensating path.

[0019] If necessary, the compensating roller acts as a tensioning roller to tension the cloth.

[0020] If necessary, the compensating roll is the tensioning roll, in particular the only tensioning roll, for tensioning the fabric. If necessary, a guide roller arranged downstream of the counter roll along the machine direction is provided for guiding or deflecting the fibrous web emerging from the nip or leaving the counter roll.

[0021] If necessary, the guide roller can be moved to change the angle of wrap of the fiber web around the counter roller.

[0022] This allows the contact time and thus the heat input of the heated counter roll to the fiber web to be adjusted.

[0023] If necessary, the wrap roller is mounted on pivot bearings on both sides.

[0024] If necessary, the adjusting device comprises means for changing and fixing the position of the pivot bearings relative to the counter roller.

[0025] If necessary, the adjusting device comprises a guide arrangement for guiding the pivot bearings or their bearing blocks and a drive for changing the position of the pivot bearings relative to the counter roller.

[0026] If necessary, the drive is a hydraulic or electromechanical drive.

[0027] If necessary, the wrapping roller and the pressure bar are arranged one after the other on the inside of the cloth along the course of the cloth.

[0028] If necessary, the counter roller is arranged in the area between the wrap roller and the pressure bar on the outside of the cloth.

[0029] If necessary, the cloth is guided in compression mode by the wrap roller and the pressure bar around the counter roller at a wrap angle.

[0030] Optionally, the fabric is an endless belt, along whose path the fabric drive roller, the pressure bar, the counter roller, the wrap roller, and the compensating roller, preferably designed as a tension roller, are arranged in succession. In all embodiments, the axes of rotation of the counter roller and the wrap roller preferably run parallel to each other. In all embodiments, the axes of rotation of the counter roller and the wrap roller preferably run parallel to each other, even if the wrap angle is or is being changed.

[0031] In all embodiments, the axes of rotation of the counter roller and the guide roller preferably run parallel to each other, and this is particularly the case when the paper web wrap angle is or is changed.

[0032] With the present edging device, the fabric can also be driven at production speed, if necessary, instead of the usual configuration of a drive roller and a non-driven fabric. Auxiliary drives for the fabric are known in the prior art, which reduce the slippage between the fabric and the drive roller when the edging device is raised. However, these only drive the fabric up to a low speed of up to 100 m / min during the edging process, not at production speed.

[0033] In the present design, however, a drive roller in the traditional sense is preferably not present. Instead, there is a blanket with a blanket drive and a counter roller with a counter roller drive. The two drives are dimensioned and designed such that they can drive the blanket and the counter roller at production speed, preferably even when the pressure bar is not pressing the blanket against the counter roller, for example, even when the blanket and the counter roller are not in direct contact or operative contact with each other. The counter roller can also be referred to or act as a Clupak cylinder or heating cylinder.

[0034] With this upsetting device, a distinction can basically be made between two operating modes:

[0035] In compression mode, the fibrous web is conveyed at production speed through the compression gap, i.e., between the moving fabric and the moving counter roll, and compressed in the machine direction. In this compression mode, the fabric is driven by a fabric drive. The fabric drive is preferably a drive that acts directly on the fabric via a fabric drive roll. In this compression mode, the counter roll is preferably also driven by its own counter roll drive. In this configuration, there are therefore two drives and two driven rolls.

[0036] In freewheel mode, the pressure bar is in the retracted position, meaning the fabric is not pressed against the counter roller, or at least less firmly. Preferably, even in freewheel mode, the fabric is driven by the fabric drive and the counter roller by the counter roller drive.

[0037] These individual drives make it possible to drive the fabric at production speed even when the pressure bar is in its retracted position and the fabric is not pressing against the counter roller.

[0038] If necessary, the speeds of the blanket and counter roll can be brought up to production speed without the need for the blanket to be placed in contact with or pressed against the counter roll. This reduces wear when the swaging device is started up and extends the maintenance interval. Furthermore, if a paper tear occurs in the system, the pressure bar can be moved immediately, for example in less than 2 seconds or preferably in less than one second, into its retracted position, which switches the swaging device from its swaging mode to free-running mode. Here, too, the blanket and counter roll can continue to move at production speed without slippage occurring between the counter roll and blanket, which would lead to severe wear on the blanket. This also extends the maintenance interval and improves the efficiency of the system.

[0039] The compression device preferably comprises a rotating fabric, a fabric drive that drives the fabric, a counter roll, a counter roll drive that drives the counter roll, and a compression gap formed between the fabric and the counter roll. The compression device preferably has a compression mode in which it is operated such that the fibrous web runs through the compression gap at production speed and is conveyed there between the moving fabric and the moving counter roll, thereby being compressed in the machine direction.

[0040] It is preferably provided that the cloth is or will be driven by the cloth drive in the compression mode.

[0041] It is preferably provided that the counter roller is driven by the counter roller drive in the compression mode, whereby in the compression mode both the cloth and the counter roller are each driven by their own drive.

[0042] If necessary, it is provided that the drive speed of the cloth drive and the counter-roller drive can be controlled or regulated independently of each other.

[0043] Where appropriate, it is provided that the rotational speed of the cloth and the rotational speed of the counter-roller in the compression mode are greater than 400 m / min, in particular greater than 600 m / min, and essentially correspond to the production speed.

[0044] If necessary, it is provided that the adjustment device is designed to displace the wrap roller and thereby to adjust the wrap angle in the compression mode, wherein the displacement can preferably take place at production speed.

[0045] Where appropriate, it is provided that the adjusting device is designed to displace the wrap roller and thereby to adjust the wrap angle at a rotational speed of the cloth and the counter roller in the compression mode of more than 400 m / min, in particular of more than 600 m / min, and essentially at production speed.

[0046] Optionally, a cloth drive roller is provided that transfers the drive torque of the cloth drive to the cloth, wherein the cloth drive roller is in particular in direct contact with the cloth, and wherein the cloth drive roller is provided in addition to the counter roller. In particular, the two drives each provide more than 25% of the required drive power. Preferably, the two drives provide approximately 50% of the required drive power.

[0047] Preferably, a tensioning roller is provided to tension the fabric in compression mode.

[0048] Preferably, an adjustable pressure bar is provided within the fabric, which is displaced toward the counter roll in the compression mode and presses the fabric toward the counter roll in the area of ​​the compression gap. In particular, the fabric is compressed between the pressure bar and the counter roll in the compression mode.

[0049] Optionally, the upsetting device has a free-running mode as an alternative to the upsetting mode. In this mode, the pressure bar is in a retracted position compared to the upsetting mode, and the fabric therefore exerts no pressure on the counter roller or a reduced pressure compared to the upsetting mode. In the free-running mode, both the fabric and the counter roller are driven by the fabric drive, and the counter roller is driven by the counter roller drive.

[0050] The rotational speed of the cloth and the rotational speed of the counter roller in free-running mode are preferably greater than 400 m / min, in particular greater than 600 m / min.

[0051] If necessary, it is provided that the pressure bar is pressed in the compression mode with a force of at least 5 kN / m, in particular of at least 45 kN / m, preferably of 5 kN / m, or 20 kN / m or 45 kN / m to 70 kN / m towards the counter roll.

[0052] If appropriate, it is provided that the cloth has a cloth thickness of more than 15 mm, in particular more than 20 mm and preferably from 20 mm to 30 mm.

[0053] Where appropriate, the cloth may have a width measured transversely to the machine direction of more than 3.5 m, in particular greater than 5.5 m. Where appropriate, the cloth may have a Shore A hardness between 40 and 70, in particular between 50 and 60.

[0054] If necessary, the counter roll is heated in compression mode.

[0055] If necessary, the counter roll is heated with a steam pressure of 2 bar to 15 bar and / or with a temperature of 70°C to 180°C.

[0056] In particular, the invention relates to a plant for producing kraft paper, comprising the following plant components:

[0057] - a wire section for forming a fibrous web by continuously applying a fibrous suspension along the machine direction through a headbox,

[0058] - a shaking device for shaking the fibrous web transversely to the machine direction, i.e. in the transverse direction,

[0059] - a press section for pressing the fibrous web partially dewatered in the wire section,

[0060] - a drying section for drying the fibrous web,

[0061] - a winding station for winding the paper web formed from the fibrous web,

[0062] - and a compression device.

[0063] Preferably, the drying section comprises a pre-drying section and a post-drying section.

[0064] If necessary, the compression device is arranged between the pre-dryer section and the after-dryer section and compresses the fibrous web between the pre-dryer section and the after-dryer section in the machine direction.

[0065] If necessary, the compression device is designed to compress the fibrous web at a dry content of the fibrous web of 55% to 70%.

[0066] In particular, the invention relates to a method for producing kraft paper, in which the fibrous web of a kraft paper production plant is compressed in a compression device, wherein the compression device is designed in particular as a Clupak device. Method steps can be:

[0067] - that a rotating cloth is driven by a cloth drive,

[0068] - that a counter roll is driven by a counter roll drive,

[0069] - that in a compression mode of the compression device, the fibrous web runs at production speed through a compression gap provided between the cloth and the counter roll and is conveyed there between the moving cloth and the moving counter roll and is thereby compressed in the machine direction, and that the cloth is driven by the cloth drive in the compression mode.

[0070] Further procedural steps may include:

[0071] - in a wire section, a fibrous web is formed by continuously applying a fibrous suspension along the machine direction through a headbox,

[0072] - the fibrous web is shaken transversely to the machine direction, i.e. in the transverse direction, by a shaker,

[0073] - in a press section the fibrous web partially dewatered in the wire section is pressed,

[0074] - the fibrous web is dried in a drying section,

[0075] - the paper web formed from the fibrous web is wound up in a winding station.

[0076] It may be advantageous if the drying section comprises a pre-drying section and a post-drying section.

[0077] It can be advantageous if the compression device compresses the fibrous web between the pre-drying section and the after-drying section in the machine direction.

[0078] It may be advantageous if the compression device compresses the fibrous web at a dry content of the fibrous web of 55% to 70%.

[0079] In particular, the invention relates to a kraft paper produced on a described system and / or produced by a described method. The invention relates, among other things, to a method for producing kraft paper, in particular sack kraft paper, in which, in a first step, a fibrous web running in the machine direction is formed. This is carried out, in particular, by applying a fibrous suspension to a wire section by means of a headbox.

[0080] In particular, after the suspension is applied to the wire section, the fiber material is shaken or jolted with a high-frequency shaking device on the breast roll. This contributes to reducing fiber alignment in the machine direction and increasing it in the cross direction.

[0081] In the wire section, a fibrous band or sheet is formed by a filtration process, in particular using dewatering devices.

[0082] Following the wire section, a press section is typically arranged, where mechanical dewatering with simultaneous compaction of the fibrous web can take place. This can typically be achieved with several press nips, the first of which is usually designed as a suction press with double felt guides, and the others as roller presses or shoe presses with either double or single felt guides.

[0083] The mechanically extruded fibrous web can be subjected to one or more drying processes to achieve the desired dry content. Further manufacturing and / or processing steps, such as compressing or calendering the fibrous web, can be performed before, between, or after one or more drying processes.

[0084] The compression of the fibrous web can occur, in particular, between two drying steps, i.e., after a pre-drying step in a pre-drying section and before a post-drying step in a post-drying section. This can increase the paper's extensibility in the machine direction. This step takes place in the compression device. Calendering or embossing of the fibrous web can, for example, take place after the last drying step. Calendering can be performed with thermal rolls or embossing rolls. Thermal rolls are used to provide the smoothest possible paper surface, while embossing rolls are used to give the paper surface a different appearance.

[0085] After the final processing step, the finished paper web can be wound up on the reel and then further processed to the desired finished roll width.

[0086] This system and / or the compression device preferably have a production speed of greater than 400 m / min. The width of the fibrous web or the produced paper web is preferably greater than 3.5 m, in particular greater than 5.5 m, typically greater than 6.0 m.

[0087] Optionally, the cloth and the counter-roller have a width of at least 4.0 m, in particular of at least 7.0 m, typically of at least 8.0 m.

[0088] Optionally, the production speed is at least 600 m / min, in particular at least 1000 m / min or at least 1100 m / min.

[0089] In particular, the fiber used to produce kraft paper is pulp made from softwood or coniferous long fibers. The kappa number of the pulp can be at least 30. The kraft paper produced can, in particular, be bleached or unbleached brown kraft paper.

[0090] Preferably, the extensibility of the kraft paper, in particular according to ISO 1924-3:2005, is greater than 5% in the transverse direction, preferably greater than 7.5%. These values ​​are preferably also met in the machine direction. The width of a paper web of the kraft paper is preferably greater than 3.5 m and in particular greater than 5.5 m, for example greater than 6.0 m. In the context of the present invention, the width refers in particular to the dimension of a paper web in the transverse direction of the paper.

[0091] Preferably, the difference in the extensibility of the paper in the transverse direction between the edge region and the center region of the paper web is a maximum of 1.5%. In absolute terms, the extensibility of the paper web can be between 5% and 8% in the center and between 7.5% and 12% at the edges, depending on the manufacturing process. The edge region refers in particular to an area 50 cm wide, starting from each outer edge of the paper web. The center region refers in particular to an area 50 cm wide, extending 25 cm on either side of the geometric center of a paper web, determined in the width direction.

[0092] An example of a possible measurement of extensibility is between 0.75 and 1.5 hours, typically 1.0 hours, after the production of the kraft paper, i.e., after completion of the final manufacturing step. However, the measurement can also be performed at a later or earlier time if necessary.

[0093] Where applicable, the Ambertec formation of the paper is not more than 0.7 (g / m 2 ).

[0094] Where appropriate, the Gurley drag of the paper, in particular according to ISO 5636-5:2013, is not more than 15 s, preferably not more than 10 s.

[0095] Where appropriate, the tensile energy absorption index of the paper in the machine direction, in particular according to ISO 1924-3:2005, is at least 2.5 J / g, preferably at least 3.0 J / g. Where appropriate, these values ​​also apply to the machine direction of the paper.

[0096] The fiber contained in the paper may be unbleached pulp. Bleached pulp may also be used if necessary.

[0097] Where appropriate, the fiber contained in the paper consists of softwood long fibers with an average fiber length of at least 2 mm. Fiber analysis can be performed, in particular, according to ISO 16065-2:2014, for example, optically using the Fiber Tester L&W.

[0098] Where appropriate, the fibre contained in the paper has a kappa number of at least 30, in particular of at least 50.

[0099] The cloth is preferably made of an elastic elastomer material, which may optionally have a reinforcing structure. The cloth can, in particular, be designed as a conventional Clupak cloth.

[0100] In all embodiments, the production speed is preferably the inlet speed of the fibrous web into the compression device.

[0101] Further features of the invention emerge from the patent claims, the figures and the description of the embodiment.

[0102] The present invention is explained in detail below using an exemplary embodiment.

[0103] They show:

[0104] Fig. 1a-c is a schematic overall view of a kraft paper manufacturing plant according to a first embodiment of the invention; and

[0105] Fig. 2 is a schematic detailed view of an upsetting device.

[0106] 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, outer side 9, breast roll 10, first dewatering section 11, inner side 12, second dewatering section 13, first dewatering device 14, second dewatering device 15, forming bar 16, suction zone 17, top former dewatering wire 18, pre-dryer section 19, after-dryer section 20, edging device 21, calendering device 22, running direction of the fibrous web 23, suction box 24, paper roll 25, fabric 26, fabric drive 27, counter roll 28, counter roll drive 29, edging gap 30, fabric drive roll 31, tension roll 32, pressure bar 33, wrap roller 34, wrap angle 35, release agent dispensing arrangement orSilicone spray device 36, scraper 37, coolant nozzle 38, adjustment device 39, compensation path 40, compensation roller 41, guide roller 42, paper web wrap angle 43, pivot bearing 44.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] The function of the individual plant components is well known to a specialist in the field of paper production and will not be explained in detail here. The following description refers specifically to wire section 2.

[0111] The fiber suspension from the headbox 3 is preferably applied to the outer side 9 of the dewatering wire 8 of the wire section 2, forming a fiber web. The machine direction 1 of the system or of the paper produced coincides with the running direction 23 of the fiber web. The dewatering wire 8 is continuously guided over an arrangement of several rolls, with the fiber suspension being applied in the area of ​​the breast roll 10 of the wire section 2. The dewatering wire 8 has, for example, a width of approximately 7.2 m.

[0112] In this embodiment, the fiber is cellulose, for example, from softwood with an average fiber length of approximately 2.2 mm. These are so-called long fibers. The pulp is unbleached and has a kappa number of approximately 60. The consistency of the fiber suspension when applied to the dewatering screen 8 is approximately 0.22%. However, bleached pulp can also be used.

[0113] The speed of the fiber suspension emerging from the headbox 3 is preferably about 2% higher than the running speed of the dewatering screen 8. The dewatering screen 8 can have a speed of about 1100 m / min.

[0114] A high-frequency shaking device 4 can be configured to oscillate the breast roll 10 and thus also the dewatering screen 8 in the region of the breast roll 10. This reduces the longitudinal alignment of the fibers in the machine direction 1, which contributes to improving the properties of the produced paper in the transverse direction, i.e., transverse to the machine direction 1. In this embodiment, the oscillation occurs at a frequency of approximately 7 Hz and an amplitude of approximately 35 mm.

[0115] Viewed in the running direction 23, after the suspension has been applied to the dewatering screen 8, the fibrous web enters a first dewatering section 11. Here, the fibrous web is dewatered downwards, i.e., from the inner side 12 of the dewatering screen 8. A first dewatering device 14 is arranged in the first dewatering section 11, which first enables a primarily gravity-driven dewatering of the fibrous web, followed by a downward suction treatment. The suction treatment takes place by means of suction boxes 24. In the first dewatering section 11, the fibrous web is dewatered exclusively downwards.

[0116] The first dewatering section 11 is followed by a second dewatering section 13, in which the fibrous web is dewatered upwards, i.e., toward the top side of the fibrous web. For this purpose, a second dewatering device 15 is provided in the area of ​​the outer side 9 of the dewatering screen 8. This second dewatering device is designed as a suction dewatering device with four consecutive suction zones 17. A continuously circulating top-forming dewatering screen 18 is guided between the second dewatering device 15 and the fibrous web and moves at the same speed as the main dewatering screen 8.

[0117] Furthermore, four formation bars 16 are preferably provided, arranged one after the other in the running direction 23 of the dewatering screen 8, which exert pressure on the inner side 12 of the dewatering screen 8 and thereby press the fibrous web toward the top former dewatering screen 18 or the second dewatering device 15. The contact pressure exerted by the formation bars 16 is adjustable between 5 and 25 kPa.

[0118] The fibrous web then exits the wire section 2 and is further processed in the other parts of the plant, as shown in Fig. 1, to be further dewatered or dried and finally to form a paper web.

[0119] Due to the treatment in wire section 2, the resulting kraft paper has a number of advantageous properties, particularly relating to the extensibility in the transverse direction and the formation of the paper.

[0120] The kraft paper produced according to the described embodiment has the following exemplary property profile:

[0121]

[0122] Fig. 2 shows a schematic view of a swaging device 21. The swaging device 21 comprises a cloth 26. The cloth 26 is an endless belt that is guided around several deflection rollers or guide rollers. In particular, the swaging device 21 comprises a cloth drive roller 31 with a cloth drive 27. The cloth drive 27 drives the cloth drive roller 31, wherein the cloth drive roller 31 is preferably in direct operative contact with the cloth 26 in order to drive it continuously.

[0123] The upsetting device 21 comprises a pressure bar 33. The pressure bar 33 is designed to be displaceable and, as in the present position, can press the fabric 26 toward or against a counterroller 28. In the present embodiment, the counterroller 28 has a counterroller drive 29. The counterroller drive 29 and the fabric drive 27 are preferably independently controllable or adjustable drives and are preferably rotary drives. A compression gap 30 is formed between the fabric 26 and the counterroller 28. The compression gap 30 is bounded on one side by the counterroller 28 and on the other side by the fabric 26.

[0124] The illustrated position of the compression device 21 essentially corresponds to the compression mode, in which the fibrous web is compressed. In the compression mode, the fibrous web runs at production speed through the compression gap 30 and is conveyed there between the moving fabric 26 and the counter roll 28, thereby being compressed in the machine direction 1.

[0125] In compression mode, the cloth 26 is driven by the cloth drive 27.

[0126] In the compression mode, the counter roller 28 is driven by the counter roller drive 29, whereby in the compression mode both the cloth 26 and the counter roller 28 are each driven by their own drive.

[0127] The rotational speed of the cloth 26 and the rotational speed of the counter roll 28 in the compression mode are preferably greater than 400 m / min, in particular greater than 600 m / min, and essentially correspond to the production speed.

[0128] The cloth drive roller 31 transmits the drive torque of the cloth drive 27 to the cloth 26. The rollers 31, 34 and 39 preferably act as cloth guide rollers.

[0129] Because the cloth 26 is pressed in the area of ​​the compression gap 30 by the pressure bar 33 towards the counter roll 28 and is thereby compressed between the pressure bar 33 towards the counter roll 28, the thickness of the cloth 26 is reduced in this area. Along the running direction 23 of the fibrous web after the pressure bar 33, the thickness of the elastically deformed cloth 26 increases again to its original thickness. Via a transverse contraction effect, the cloth 26 contracts by a certain amount along its direction of movement, whereby the speed of the cloth 26 is locally reduced. Because the fibrous web rests against the cloth 26 in this area, the fibrous web is compressed by this effect. This compression takes place in the machine running direction 1 . .The process can preferably be adjusted by adjusting the wrap-around roller 34 so that the contact time of the fibrous web between the cloth 26 and the counter roller 28 can be adjusted at an angle of approximately 15°-90°, preferably between 20°-45°.

[0130] By displacing the pressure bar 33, as shown in dashed lines, the pressure or force acting on the fabric 26 in front of the pressure bar 33 toward the counter roll 28 can be reduced or completely eliminated. By relieving the pressure bar 33 in this way, the upsetting device 21 can be put into a free-running mode. In both operating modes, i.e., upsetting mode and free-running mode, the two drives can preferably drive the fabric 26 and the counter roll 28. Preferably, the drive takes place at a speed that essentially corresponds to the production speed.

[0131] In the present embodiment, the compression device 21 comprises a tensioning roller 32. The tensioning roller 32 serves to maintain the tension of the fabric 26. The tensioning roller 32 is preferably designed to be displaceable and maintains the tension of the fabric 26, for example, when it stretches due to wear.

[0132] In addition, the tension roller 32 can also keep the cloth 26 taut if necessary when the pressure bar 33 is retracted.

[0133] In the present embodiment, the upsetting device 21 comprises a wrap-around roller 34. The wrap-around roller 34 is arranged such that the path of the cloth 26 runs, at least in one section, along the outer contour of the counter-roller 28. The position of the wrap-around roller 34 thus determines the wrap angle 35 of the cloth 26 on the counter-roller 28. The greater the wrap angle 35, the longer the contact distance of the cloth 26 and thus also of the fibrous web on the counter-roller 28. In the upsetting mode, the cloth 26 is therefore guided by the wrap-around roller 34 and the pressure bar 33 by a wrap angle 35 around the counter-roller 28.

[0134] In the present embodiment, the wrap roller 34 is designed to be displaceable in order to be able to adjust or change the wrap angle 35.

[0135] This is achieved via a schematically illustrated adjustment device 39, with which the wrap angle 35 can be changed and adjusted by moving the wrap roller 34. In the present embodiment, the adjustment device 39 comprises guides or guide arms arranged on both sides of the wrap roller 34 and a drive. By actuating the drive, the pivot bearings for supporting the wrap roller 34 can be moved in a targeted manner.

[0136] Preferably, the wrap angle 35 can be adjusted by at least 10°, in particular by at least 20°, in particular by at least 25°, in particular by at least 40° or in particular by at least 60°. The displacement is preferably carried out using an electromechanical adjusting device, although the movement can also be carried out hydraulically. The displacement movement is carried out, for example, linearly by means of a spindle lifting element, wherein the wrap roller 34 is mounted via a pivot point so that the wrap angle 35 of the fabric 26 on the counter roller 28 can be adjusted (min. / max. movement). The maximum stroke of the adjusting device essentially corresponds to the maximum wrap of the fabric 26 on the counter roller 28. If the adjusting device is fully retracted, there may be no fabric contact with the counter roller 28. The fabric 26 can be operated in freewheel mode. All movement sequences should and must be synchronous.The movement sequences include, in particular, the adjustment of the cloth 26 on the counter rollers 28 and the tensioning of the cloth 26 to compensate for the change in length. When relieving the pressure rod or pressure beam 33, the movements should also be synchronized with the cloth movement, and in particular, within a period of less than 2 seconds, preferably less than 1 second.

[0137] In all embodiments, all three movements preferably occur synchronously: adjusting the wrap roller 34, tensioning the fabric 26 with the tension roller 32, and relieving the pressure on the pressure rod 33. This ensures that the fabric 26 can continue to operate at full operating speed. If necessary, the wrap angle 35 can be adjusted between 15° and 90°, preferably between 20° and 60°.

[0138] With this design, compensation for the displacement of the

[0139] Wrapping roller 34 can be adjusted at a substantially constant cloth length by displacing a compensating roller 41 that is displaceable along a compensation path 40. If the wrapping roller 34 is displaced to change the wrap angle 35, this change in the position of the wrapping roller 34 must be compensated for by changing the bearings of the compensating roller 41. Finally, the cloth 26 has a substantially constant length and should stretch only slightly along its longitudinal extent.

[0140] The compensating roller 41 can be moved along the compensating path 40, for example, by more than 10 cm, in particular by more than 45 cm and preferably between 5 cm and 55 cm.

[0141] In the present embodiment, the compensating roller 41 simultaneously acts as a tensioning roller 32 for tensioning the cloth 26. In particular, the compensating roller 41 is the only tensioning roller 32 for tensioning the cloth 26.

[0142] The fibrous web is wrapped around the counter roller 28 at a paper web wrap angle 43. After leaving the counter roller 28, the fibrous web is guided or deflected around a guide roller 42. The paper web wrap angle 43 of the fibrous web around the counter roller 28 can be changed by changing the position of the guide roller 42.

[0143] The compression device 21 according to Fig. 2 comprises a release agent dispensing arrangement, in particular a silicone spray device 36, and preferably also a scraper 37. The silicone spray device 36 applies release agent to the surface of the counter roll 28. This reduces the tendency of the fibrous web to adhere to the counter roll 28. Excess release agent can be scraped off and collected via the scraper 37. In particular, several silicone spray devices 36 can be provided to distribute the release agent across the entire width of the counter roll 28.

[0144] A coolant nozzle 38 may also be provided, which can be used to provide the surface of the compression belt 26 with a coolant.

[0145] In particular, a plurality of coolant nozzles 38 are provided to distribute the coolant over the entire width of the cloth 26.

Claims

Patent claims 1. Upsetting device (21), in particular a Clupak device, for upsetting a fibrous web of a plant for producing kraft paper, - wherein a rotating cloth (26), a pressure bar (33), a wrap-around roller (34), a counter-roller (28) and preferably a cloth drive roller (31) are provided, - wherein the compression device (21) has a compression mode in which the rotating cloth (26) is pressed by the pressure bar (33) towards the counter-roller (28) and in which the cloth (26) wraps around the counter-roller (28) by a wrap angle (35), - wherein in the compression mode, a compression gap (30) is formed between the cloth (26) and the counter-roller (28), which is designed to convey the fibrous web through at production speed and to compress it in the machine direction (1), characterized in that an adjusting device (39) is provided for displacing the wrap-around roller (34) and thereby for changing and adjusting the wrap angle (35).

2. Upsetting device (21) according to claim 1, characterized in that the adjusting device (39) is designed such that - that the wrap angle (35) of the cloth can be adjusted by at least 10°, in particular by at least 20°, in particular by at least 25°, in particular by at least 40° or in particular by at least 60°, - and / or that the wrap angle (35) is adjusted between 15° and 90°, preferably between 20° and 60°.

3. Upsetting device (21) according to claim 1 or 2, characterized in that a compensating roller (41) displaceable along a compensating path (40) is provided to compensate for the displacement of the wrap-around roller (34) at a substantially constant cloth length.

4. Upsetting device (21) according to claim 3, characterized in that the compensating roller (41) has a freedom of movement along the compensating path (40) or has a stroke of more than 10cm, in particular more than 45cm and preferably between 5cm and 55cm.

5. Upsetting device (21) according to claim 3 or 4, characterized in that - that the compensating roller (41) acts as a tensioning roller (32) for tensioning the cloth, - in particular that the compensating roller (41) is the tensioning roller (32) for tensioning the cloth.

6. Upsetting device (21) according to one of claims 1 to 5, characterized in that - that a guide roller (42) arranged downstream of the counter roller (28) along the machine running direction (1 ) is provided for guiding or deflecting the fibrous web emerging from the compression gap or leaving the counter roller (28), - and that the guide roller (42) is displaceable in order to change the paper web wrap angle (43) of the fibrous web around the counter roller.

7. Upsetting device (21) according to one of claims 1 to 6, characterized in that - that the wrap roller (34) is mounted on both sides in pivot bearings (44), - and that the adjusting device (39) comprises means for changing and fixing the position of the rotary bearings (44) relative to the counter-roller (28).

8. Upsetting device (21) according to claim 7, characterized in that - that the adjusting device (39) comprises a guide arrangement for guiding the pivot bearings or their bearing blocks and a drive for changing the position of the pivot bearings relative to the counter-roller, - wherein the drive is in particular a hydraulic or an electric drive.

9. Upsetting device (21) according to one of claims 1 to 8, characterized in that - that the wrap roller (34) and the pressure bar (33) are arranged along the Course of the cloth (26) are arranged one after the other on the inside of the cloth (26), - and that the counter roller (28) is arranged in the area between the wrap-around roller (34) and the pressure bar (33) on the outside of the cloth (26).

10. Upsetting device (21) according to one of claims 1 to 9, characterized in that the cloth (26) is guided in the upsetting mode by the wrap roller (34) and the pressure bar (33) around the counter roller (28) by a wrap angle (35).

11. Upsetting device (21) according to one of claims 1 to 10, characterized in that the cloth (26) is an endless belt, along the course of which the cloth drive roller (31), the pressure bar (33), the counter roller (28), the wrap-around roller (34) and the compensating roller (41), preferably designed as a tensioning roller (32), are arranged one after the other.

12. Upsetting device (21) according to one of claims 1 to 11, characterized in that - that the rotational speed of the cloth (26) and the rotational speed of the counter-roller (28) in the compression mode are greater than 400 m / min, in particular greater than 600 m / min, and essentially correspond to the production speed - and / or that the adjusting device (39) is designed to displace the wrap roller (34) and thereby to adjust the wrap angle (35) in or during the compression mode and preferably at production speed.

13. Upsetting device (21) according to one of claims 1 to 12, characterized in that the pressure bar (33) is pressed in the upsetting mode with a force of at least 5 kN / m, in particular of at least 45 kN / m, preferably of 5 kN / m or 45 kN / m to 70 kN / m towards the counter-roller (28).

14. Upsetting device (21) according to one of claims 1 to 13, characterized in that - that the cloth (26) has a thickness of more than 15 mm, in particular more than 20 mm and preferably from 20 mm to 30 mm, - and / or that the cloth (26) has a cloth width measured transversely to the machine direction (1 ) of more than 3.5 m, in particular of greater than 5.5 m, and / or that the cloth (26) has a Shore A hardness between 40 and 60, in particular between 50 and 60.

15. Upsetting device (21) according to one of claims 1 to 14, characterized in that - that the counter roll (28) is heated in the compression mode, - in particular that the counter roller (28) is heated with a steam pressure of 2 bar to 15 bar and / or with a temperature of 70°C to 180°C.

16. 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, - and a compression device (21) according to one of the preceding claims.

17. Plant according to claim 16, characterized in that - that the drying section (6) comprises a pre-drying section (19) and a post-drying section (20), - that the compression device (21) is arranged between the pre-drying section (19) and the after-drying section (20) and compresses the fibrous web between the pre-drying section (19) and the after-drying section (20) in the machine direction (1).

18. Plant according to claim 16 or 17, characterized in that the compression device (21) compresses the fibrous web at a dry content of the fibrous web of 55% to 70%.

19. Method for compressing a fibrous web in a compression device (21) of a plant for producing kraft paper, - wherein the compression device (21) comprises a circulating cloth (26), a pressure bar (33), a wrap-around roller (34), a counter-roller (28) and preferably a cloth drive roller (31), - wherein the compression device (21) has a compression mode in which the rotating cloth (25) is pressed by the pressure bar (33) towards the counter-roller (28) and wraps around the counter-roller (28) by a wrap angle (34), - wherein in the compression mode, a compression gap (30) is formed between the cloth (26) and the counter-roller (28), which is designed to convey the fibrous web through at production speed and thereby compress it in the machine direction (1), characterized in that the wrap angle (35) can be changed and adjusted by displacing the wrap roller (34) by means of an adjusting device (39).

20. Method according to claim 19, characterized in that the wrap angle (35) can be adjusted by at least 10°, in particular by at least 20°, in particular by at least 25°, in particular by at least 40° or in particular by at least 60°, - and / or that the wrap angle can be adjusted between 15° and 90°, preferably between 20° and 60°.

21. Method according to claim 19 or 20, characterized in that compensation of the displacement of the wrap-around roller (34) with a substantially constant cloth length is carried out by displacing a compensating roller (41) which can be displaced along a compensating path (40).

22. Method according to claim 21, characterized in that the compensating roller (41) is displaced along the compensating path (40) by more than 10 cm, in particular by more than 45cm and preferably between 5cm or 10cm and 55cm.

23. Method according to claim 21 or 22, characterized in that - that the compensating roller (41) acts as a tensioning roller (32) to tension the cloth (26), - in particular that the compensating roller (41) is the tensioning roller (32) for tensioning the cloth (26).

24. Method according to one of claims 19 to 23, characterized in that - that the fibrous web emerging from the compression gap (30) or leaving the counter roll (28) is guided or deflected by a guide roll (42) arranged downstream of the counter roll (28) along the machine running direction (1 ), - and that the guide roller (42) can be displaced to change the paper web wrap angle (43) of the fibrous web around the counter roller (28).

25. Method according to one of claims 19 to 24, characterized in that the cloth (26) is guided in the compression mode by the wrap roller (34) and the pressure bar (33) around the counter roller (28) by a wrap angle (35).

26. Method according to one of claims 19 to 25, characterized in that the rotational speed of the cloth (26) and the rotational speed of the counter-roller (28) in the compression mode are greater than 400 m / min, in particular greater than 600 m / min, and essentially correspond to the production speed, - and / or that the adjusting device (39) changes or can change the position of the wrap roller (34) and thereby the wrap angle (35) in or during the compression mode and preferably at production speed.

27. Method according to one of claims 19 to 26, characterized in that the pressure bar (33) in the compression mode with a force of at least 5 kN / m, in particular of at least 45 kN / m, preferably of 5 kN / m or 45 kN / m to 70 kN / m towards the counter roller (28).

28. Method according to one of claims 19 to 27, characterized in that - that the cloth (26) has a cloth thickness of more than 15 mm, in particular more than 20 mm and preferably from 20 mm to 30 mm, - and / or that the cloth (26) has a cloth width measured transversely to the machine direction (1 ) of more than 3.5 m, in particular of greater than 5.5 m, and / or that the cloth (26) has a Shore A hardness between 40 and 60, in particular between 50 and 60.

29. Method according to one of claims 19 to 28, characterized in that - that the counter roll (28) is heated in the compression mode, - in particular that the counter roller (28) is heated with a steam pressure of 2 bar to 15 bar and / or with a temperature of 70°C to 180°C.

30. Method according to one of claims 19 to 29, characterized in that - in a wire section (2) a fibrous web is formed by continuously applying a fibrous suspension along the machine direction (1) through a headbox (3), - the fibrous web is shaken by a shaker transversely to the machine direction (1 ), i.e. in the transverse direction, - in a press section (5) the fibrous web partially dewatered in the wire section (2) is pressed, - the fibrous web is dried in a drying section (6), - the paper web formed from the fibrous web is wound up in a winding station (7). 31 . Method according to claim 30, characterized in that - that the drying section (6) comprises a pre-drying section (19) and a post-drying section (20), - and that the compression device (21) compresses the fibrous web between the pre-drying section (19) and the after-drying section (20) in the machine direction (1).

32. Method according to one of claims 19 to 31, characterized in that the compression device (21) compresses the fibrous web at a dry content of the fibrous web of 60% to 70%.

33. Kraft paper produced on a plant according to any one of claims 16 to 18 and / or produced by a process according to any one of claims 19 to 32.

Images