Compressing device, and method for producing kraft paper

Abstract

The invention relates to a compressing device (21), in particular a Clupak device, for compressing a fibrous web in a plant for producing Kraft paper, wherein the compressing device (21) has an endless blanket (26), a counter-roller (28), and a compression nip (30) formed between the blanket (26) and the counter-roller (28), wherein the compression device (21) has a compression mode in which it is operated in such a way that the fibrous web passes through the compression nip (30) at production speed, and is conveyed therein between the moving blanket (26) and the moving counter-roller (28), and is thereby compressed in the machine running direction (1), wherein a release agent dispensing arrangement (36) having release agent nozzles (61) is provided for dispensing a release agent onto the lateral surface of the counter-roller (28), wherein the release agent nozzles (61) comprise intermittently operated nozzle valves (62) for discontinuous, pulsed dispensing of the release agent.

Description

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

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

[0003] Various devices and 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 stretchability of kraft paper, a distinction is generally made between stretchability in the machine direction and stretchability across the machine direction, i.e., in the cross direction. To influence stretchability in the machine direction, it is known to use a compression device that compresses the fiber web in the machine direction as it passes through the production line.

[0005] A widely used device for continuously compressing a fibrous web in the machine direction is a so-called "Clupak" device. In this type of compressing device, the fibrous web is conveyed through a compression gap. This compression gap is defined on one side by a compression belt known as the "cloth" and on the other side by a drive roller. The cloth is usually a continuously 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 cloth between the counter roller and the pressure bar, thereby locally reducing its thickness. After passing the pressure bar, the cloth expands again, which leads to a local deceleration of the cloth due to a transverse contraction effect.In this area, the fibrous web rests against the fabric, causing it to be compressed in the machine direction during the described deceleration 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.

[0006] 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.

[0007] Another disadvantage of known upsetting 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 roller creates high frictional forces on the fabric. These frictional forces and the relative movement cause significant wear. In practice, this leads to the fabric requiring frequent maintenance or replacement.

[0008] Since paper cannot be produced with the desired parameters during maintenance and adjustment, maintenance of the edging device reduces the efficiency of the system. For this reason, efforts 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.

[0009] Another disadvantage of conventional compression devices is that excessive adhesion between the fibrous web and the counter roll negatively impacts the compression effect. To reduce this problem, a known approach is to apply a release agent to the counter roll. This release agent is intended to reduce the adhesion between the fibrous web and the counter roll of the compression device, thus improving the effectiveness and consequently the efficiency of the compression device.

[0010] In addition, the release agent also helps in the event of a paper tear to reduce the friction between the cloth and the counter roller and thus reduce wear on the cloth.

[0011] The release agent, which contains a silicone oil, for example, is usually applied to the counter roll via spray nozzles. The dosage of the agent is of great importance here. On the one hand, as little release agent as possible should be used. On the other hand, sufficient release agent must be used to achieve the desired effect. Dosing is made more difficult by the fact that the nozzles can become dirty or blocked by the continuous dispensing of the release agent. The spray nozzles therefore have to be serviced and, in particular, cleaned from time to time. During maintenance, paper production is generally not possible, which can reduce the efficiency of the overall plant. The object of the present invention is therefore to improve the efficiency of a plant for producing kraft paper.In this case, efficiency is improved, for example, by being able to set and permanently maintain the desired release agent dosage. However, efficiency can also be improved by reducing maintenance time or extending maintenance intervals.

[0012] The problem is solved in particular by the features of the independent patent claims.

[0013] The invention preferably relates to a compression device, in particular a Clupak device, for compressing a fibrous web of a plant for producing kraft paper.

[0014] The upsetting device preferably comprises a rotating cloth, a counter roll and an upsetting gap formed between the cloth and the counter roll.

[0015] The compression device preferably has a compression mode in which it is operated in such a way that the fibrous web runs through the compression gap at production speed and is conveyed there between the moving cloth and the moving counter roll and is thereby compressed in the machine direction.

[0016] Preferably, a release agent dispensing arrangement with release agent nozzles is provided for dispensing a release agent onto the outer surface of the counter roll.

[0017] Preferably, the release agent nozzles have clocked nozzle valves for discontinuous, pulsed discharge of the release agent.

[0018] Preferably, a nozzle bar is provided along the course of which the nozzles are arranged.

[0019] The nozzle bar preferably runs parallel to the rotational axis of the counter roll. If necessary, the nozzles can be designed to dispense the release agent across the entire width of the counter roll. The entire width is the width against which the fibrous web rests in compression mode.

[0020] If necessary, it is provided that the nozzle valves have a clock frequency, i.e. a frequency of the release agent outputs per second, of 10Hz to 30Hz, preferably of 15Hz to 25Hz.

[0021] If necessary, the nozzle valves are provided with an adjustable clock frequency of 10Hz to 30Hz, preferably of 15Hz to 25Hz.

[0022] If necessary, the nozzle valves are provided with an adjustable opening duration for the individual pulses of the release agent outputs.

[0023] Where appropriate, the opening duration of the nozzle valves per pulse is between 400ps and 1200ps, in particular between 500ps and 1000ps.

[0024] If necessary, it is provided that the nozzle pressure, in particular the pressure that the release agent has in the area immediately in front of the release agent nozzle, is between 1 bar and 3 bar.

[0025] If necessary, the volume flow of the release agent per release agent nozzle is between 50 ml / min and 600 ml / min, preferably between 80 ml / min and 500 ml / min.

[0026] If necessary, the total volume flow of the release agent, depending on the length of the nozzle bar, is between 0.151 / min and 11 / min per meter of length of the nozzle bar.

[0027] If necessary, the total volume flow for a 6 m long nozzle bar is between 11 / min and 61 / min.

[0028] Where appropriate, it is provided that the release agent comprises silicone oil, - in particular that the release agent comprises silicone oil and water,

[0029] - in particular, that the release agent comprises between 5% and 20% silicone oil and between 95% and 80% water,

[0030] - in particular, that the release agent comprises 10% silicone oil and 90% water,

[0031] - and preferably, the release agent has a viscosity according to ISO 3219 of 150 mPAs to 250 mPAs and in particular of 200 mPAs.

[0032] If necessary, a mixing container is provided for mixing the components of the release agent, in particular for mixing water and silicone oil.

[0033] If necessary, a pressure vessel is provided in which the release agent is provided under overpressure for dispensing through the release agent nozzles.

[0034] If necessary, the nozzle bar may include a distribution line that distributes the release agent to several or all nozzles.

[0035] If necessary, a scraper is provided which scrapes the release agent dispensed by the release agent dispensing arrangement from the counter roller.

[0036] In particular, the invention relates to a method for operating a compression device, in particular a Clupak device, for compressing a fibrous web of a plant for producing kraft paper.

[0037] Optionally, the method comprises the step of operating the compression device in a compression mode such that the fibrous web runs through the compression gap at production speed and is conveyed there between the moving cloth and the moving counter roll and is thereby compressed in the machine direction.

[0038] Optionally, the method comprises the step of a release agent dispensing arrangement with release agent nozzles dispensing a release agent onto the outer surface of the counter roll. Preferably, the method comprises the step of dispensing the release agent discontinuously, in pulsed fashion, through the nozzles via synchronously operated nozzle valves.

[0039] Optionally, the method comprises the step of discharging the release agent over the entire width of the counter roll via a nozzle bar running parallel to the axis of rotation of the counter roll, along the length of which the nozzles are arranged.

[0040] This compression device features an adjustment option rather than the conventional rigid, unchangeable configuration. This adjustment option allows for flexible adjustment of the compression. The design allows for rapid adjustment of the compression device, thereby improving the efficiency of the system. Furthermore, the adjustability enables the production of kraft paper with different material parameters. This makes the system more profitable and therefore more efficient from an economic perspective.

[0041] With this edging device, instead of the usual configuration of a drive roller and a non-driven fabric, the fabric can also be driven at production speed. 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.

[0042] In the present construction, however, a drive roller in the conventional sense is preferably not present. Rather, there is preferably a fabric with a fabric drive and a counter roller with a counter roller drive. The two drives are dimensioned and designed in such a way that they can drive the fabric and the counter roller at production speed, preferably even when the pressure bar is not pressing the fabric against the counter roller, for example, even when the fabric and the counter roller are not in direct contact or operative contact with each other. The counter roller can optionally also be referred to or act as a Clupak cylinder or heating cylinder. In the present upsetting device, it is possible to distinguish between two

[0043] Operating modes can be distinguished:

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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. This switches the swaging device from its swaging mode to free-running mode or an emergency 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.

[0048] In particular, the design relates to a compression device, optionally a Clupak device, and / or a method for compression of a fibrous web of a plant for producing kraft paper.

[0049] Preferably, a circulating cloth, a pressure bar, a wrap-around roller, a counter roller and preferably a cloth drive roller are provided.

[0050] Preferably, the compression device has a compression mode in which the circulating cloth is pressed by the pressure bar towards the counter roller and in which the cloth wraps around the counter roller by a wrap angle.

[0051] Preferably, in the compression mode, a compression gap is formed between the cloth and the counter roll, which is designed to convey the fibrous web through at production speed and thereby compress it in the machine direction.

[0052] Preferably, an adjusting device is provided for displacing the wrap roller and thereby for adjusting the wrap angle.

[0053] By changing the wrap angle, the compression of the fibrous web can be adjusted flexibly and precisely, in particular controlled and / or regulated.

[0054] If necessary, the adjustment device is designed in such a way

[0055] - 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°.

[0056] Optionally, the adjustment device is designed such that the wrap angle of the fabric can be adjusted between 15° and 90°, preferably between 20° and 60°. Optionally, a compensating roller is provided that can be displaced along a compensation path to compensate for the displacement of the wrap roller while maintaining a substantially constant fabric length.

[0057] 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.

[0058] If necessary, the compensating roller acts as a tensioning roller to tension the cloth.

[0059] If necessary, the compensating roller is the tensioning roller, in particular the only tensioning roller, for tensioning the fabric.

[0060] If necessary, a guide roller arranged downstream of the counter roller along the machine direction is provided for guiding or deflecting the fibrous web emerging from the compression gap or leaving the counter roller.

[0061] If necessary, the guide roller can be moved to change the angle of wrap of the fiber web around the counter roller.

[0062] This allows the contact time and thus the heat input of the heated counter roll to the fiber web to be adjusted.

[0063] If necessary, the wrap-around roller is mounted on pivot bearings on both sides. If necessary, the adjustment device includes means for changing and fixing the position of the pivot bearings relative to the counter roller.

[0064] If necessary, the adjustment 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.

[0065] The drive may be hydraulic or electromechanical. The wrap roller and pressure bar may be arranged one after the other on the inside of the fabric along its path.

[0066] If necessary, the counter roller is arranged in the area between the wrap roller and the pressure bar on the outside of the cloth.

[0067] 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.

[0068] If necessary, the cloth is an endless belt, along the course of which the cloth drive roller, the pressure bar, the counter roller, the wrap-around roller and the compensating roller, which is preferably designed as a tensioning roller, are arranged one after the other.

[0069] In all embodiments, the axes of rotation of the counter roll and the wrap-around roll preferably run parallel to each other. In all embodiments, the axes of rotation of the counter roll and the wrap-around roll preferably run parallel to each other, even if the wrap angle is or is changed.

[0070] 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.

[0071] Preferably, the upsetting device comprises a rotating cloth, a cloth drive driving the cloth, a counter roll, a counter roll drive driving the counter roll and an upsetting gap formed between the cloth and the counter roll.

[0072] Preferably, the compression device 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 cloth and the moving counter roll and is thereby compressed in the machine running direction.

[0073] Preferably, the fabric is driven by the fabric drive in compression mode. Preferably, the counter roller is driven by the counter roller drive in compression mode, whereby both the fabric and the counter roller are each driven by their own drive in compression mode.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] Optionally, it is provided that a cloth drive roller is provided which transmits 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.

[0079] 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.

[0080] Preferably, a tensioning roller is provided for tensioning the fabric in compression mode. Preferably, an adjustable pressure bar is provided within the fabric, which is displaced toward the counterroller in compression mode and presses the fabric toward the counterroller in the area of ​​the compression gap. In particular, the fabric is compressed between the pressure bar and the counterroller in compression mode.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] Where appropriate, the fabric shall have a width measured transversely to the machine direction of more than 3.5 m, in particular greater than 5.5 m.

[0086] Where appropriate, the cloth shall have a Shore A hardness between 40 and 70, in particular between 50 and 60.

[0087] If necessary, the counter roll is heated in compression mode.

[0088] Optionally, 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. In particular, the invention relates to a plant for producing kraft paper, comprising the following plant components:

[0089] - a wire section for forming a fibrous web by continuously applying a fibrous suspension along the machine direction through a headbox,

[0090] - a shaking device for shaking the fibrous web transversely to the machine direction, i.e. in the transverse direction,

[0091] - a press section for pressing the fibrous web partially dewatered in the wire section,

[0092] - a drying section for drying the fibrous web,

[0093] - a winding station for winding the paper web formed from the fibrous web,

[0094] - and a compression device.

[0095] Preferably, the drying section comprises a pre-drying section and a post-drying section.

[0096] 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.

[0097] If necessary, the compression device is designed to compress the fibrous web at a dry content of the fibrous web of 55% to 70%.

[0098] In particular, the invention relates to a method for producing kraft paper, in which the fibrous web of a plant for producing kraft paper is compressed in a compression device, wherein the compression device is designed in particular as a Clupak device.

[0099] Procedural steps can be:

[0100] - that a rotating cloth is driven by a cloth drive,

[0101] - that a counter roll is driven by a counter roll drive,

[0102] - 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.

[0103] Further procedural steps may include:

[0104] - in a wire section, a fibrous web is formed by continuously applying a fibrous suspension along the machine direction through a headbox,

[0105] - the fibrous web is shaken transversely to the machine direction, i.e. in the transverse direction, by a shaker,

[0106] - in a press section the fibrous web partially dewatered in the wire section is pressed,

[0107] - the fibrous web is dried in a drying section,

[0108] - the paper web formed from the fibrous web is wound up in a winding station.

[0109] It may be advantageous if the drying section comprises a pre-drying section and a post-drying section.

[0110] 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.

[0111] It may be advantageous if the compression device compresses the fibrous web at a dry content of the fibrous web of 55% to 70%.

[0112] In particular, the invention relates to a kraft paper produced on a described plant and / or produced by a described method.

[0113] The invention relates, among other things, to a process 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 done, in particular, by applying a fibrous suspension to a wire section by means of a headbox. In particular, after the suspension has been applied to the wire section, the fibrous 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.

[0114] In the wire section, a fibrous band or sheet is formed by a filtration process, in particular using dewatering devices.

[0115] 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.

[0116] 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.

[0117] The compression of the fibrous web can be performed particularly 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.

[0118] Calendering or embossing of the fiber web can, for example, take place after the final drying step. Calendering can be performed using either 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. 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.

[0119] 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.

[0120] 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.

[0121] Where appropriate, the production speed is at least 600 m / min, in particular at least 1100 m / min.

[0122] 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.

[0123] 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.

[0124] Preferably, the width of a paper web of the kraft paper is greater than 3.5 m and in particular greater than 5.5 m, for example greater than 6.0 m. In connection with the present invention, the width refers in particular to the dimension of a paper web in the transverse direction of the paper.

[0125] 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.

[0126] 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.

[0127] Where applicable, the Ambertec formation of the paper is not more than 0.7 (g / m 2 ).

[0128] 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.

[0129] 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.

[0130] The fiber contained in the paper may be unbleached pulp. Bleached pulp may also be used if necessary.

[0131] 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.

[0132] Optionally, the fiber contained in the paper has a kappa number of at least 30, in particular of at least 50. 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.

[0133] In all embodiments, the production speed is preferably the inlet speed of the fibrous web into the compression device.

[0134] Further features of the invention emerge from the patent claims, the figures and the description of the embodiment.

[0135] The present invention is explained in detail below using an exemplary embodiment.

[0136] They show:

[0137] Fig. 1a-c is a schematic overall view of a kraft paper manufacturing plant according to a first embodiment of the invention; and

[0138] Fig. 2 is a schematic detailed view of an upsetting device, and Fig. 3 is a schematic structure of a release agent dispensing arrangement.

[0139] 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 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, knock-off device 45, bypass arrangement 46, bypass path 47, switch 48, cable guide 49, release agent nozzle 61, nozzle valve 62, nozzle bar 63, pressure source 64, thinner source 65, release agent source 66, mixing tank 67, pressure tank 68, distribution line 69.

[0140] Fig. 1a-c show a schematic overall view of a kraft paper production plant according to a first embodiment. The plant may comprise, 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 may alternatively be designed as an embossing device.

[0141] 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.

[0142] The production speed of the system in this exemplary embodiment may be approximately 1100 m / min in all embodiments. The produced paper web may have a paper width of approximately 6.4 m in all embodiments.

[0143] 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.

[0144] The kraft paper produced according to the described embodiment can have the following exemplary property profile:

[0145]

[0146] 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.

[0147] 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.

[0148] 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. In the compression mode, the fabric 26 is preferably driven by the fabric drive 27.

[0149] 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.

[0150] 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.

[0151] 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.

[0152] 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°.

[0153] 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.

[0154] 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.

[0155] In addition, the tension roller 32 can also keep the cloth 26 taut if necessary when the pressure bar 33 is retracted.

[0156] 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.

[0157] 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.

[0158] This is done via a schematically illustrated adjustment device 39, with which the wrap angle 35 can be changed and adjusted by moving the wrap roller 34.

[0159] In the present embodiment, the adjusting device 39 comprises on both sides of the

[0160] Guides or guide arms and a drive are arranged on the wrap roller 34. By operating the drive, the pivot bearings for supporting the wrap roller 34 can be moved in a targeted manner.

[0161] 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.

[0162] In all embodiments, all three movements preferably run synchronously: adjusting the wrap roller 34, tensioning the cloth 26 with the tension roller 32 and relieving the pressure on the pressure rod 33. This ensures that the cloth 26 can continue to operate at full operating speed.

[0163] If necessary, the wrap angle 35 can be adjusted between 15° and 90°, preferably between 20°-60°.

[0164] In the present design, the displacement of the wrap roller 34 can be compensated for while maintaining a substantially constant cloth length by displacing a compensating roller 41 that is displaceable along a compensation path 40. If the wrap roller 34 is displaced to change the wrap angle 35, this change in the position of the wrap 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.

[0165] 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.

[0166] 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.

[0167] 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.

[0168] The compression device 21 according to Fig. 2 comprises a release agent dispensing arrangement 36 and preferably also a scraper 37. The release agent dispensing arrangement 36 applies release agent to the surface or the outer 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.

[0169] The release agent dispensing arrangement 36 comprises a plurality of release agent nozzles 61, with only one release agent nozzle 61 being visible in Fig. 2. The release agent nozzles 61 are controlled by nozzle valves 62 and meter the release agent onto the counter roll 28. In order to be able to apply the release agent across the entire width of the counter roll 28, the nozzle valves 62 are arranged side by side along a nozzle bar 63. Fig. 3 shows a schematic structure of a possible embodiment of a release agent dispensing arrangement 36.

[0170] The release agent dispensing arrangement 36 comprises a pressure source 64, which is particularly designed as a compressed air source. The release agent dispensing arrangement 36 also comprises a diluent source 65, which is particularly a water supply line. The arrangement further comprises a release agent source 66, from which the release agent component, for example, a silicone oil, is provided. As an alternative to the separate provision of individual components of the release agent, a premixed release agent or a release agent with the desired composition or viscosity can also be provided in a tank or from a source.

[0171] The diluent and the release agent component can be mixed in a mixing tank 67. Optionally, the mixing tank 67 is equipped with a circulation pump and / or a mixer to ensure uniform mixing of the release agent components.

[0172] The arrangement comprises a pressure vessel 68. The pressure vessel 68 contains, on the one hand, the release agent, for example, a mixture of water and silicone oil. On the other hand, the pressure source 64 is connected to the pressure vessel 68 in order to pressurize the contents of the pressure vessel 68. The nozzle bar 63 is connected to the pressure vessel 68. The nozzle bar 63 comprises a distribution line 69 which distributes the release agent evenly to the individual nozzle valves 62 or to the individual release agent nozzles 61. The schematic representation in Fig. 3 only shows some of the release agent nozzles 61 and the associated nozzle valves 62 of the nozzle bar 63. The number of release agent nozzles 61 can be selected depending on the width of the counter roll 28 or the length of the nozzle bar 63.

[0173] The release agent nozzles 61 are operated in a timed manner by the nozzle valves 62. Specifically, the release agent is dispensed discontinuously and in pulsed increments through the release agent nozzles 61. By selecting the frequency of the pulsed dispensing and the opening duration of the individual pulses, precise dosing of the release agent can be adjusted. Furthermore, the special, timed dispensing can reduce contamination of the release agent nozzles 61. If necessary, the amount of release agent effectively used can be reduced while simultaneously reducing contamination of the release agent nozzles 61.

[0174] The clock frequency of the nozzle valves 62 is, for example, 15 Hz to 25 Hz, preferably approximately 20 Hz. In particular, the clock frequency of the nozzle valves 62 can be adjusted. The opening duration of the individual pulses can, for example, be between 400 ps and 1200 ps, ​​preferably between 500 ps and 1000 ps. The opening duration of the nozzle valves 62 per pulse can also be preferably selected and adjusted.

[0175] In all embodiments, the release agent is preferably dispensed consistently and continuously onto the counter roll 28 during the compression mode, although the dispensing itself is pulsed. However, it is important that the counter roll 28 is always provided with the desired amount of release agent during the compression mode.

[0176] Dosing can be carried out in particular by a control system and a pulse width modulation effected by the control system.

[0177] The nozzle pressure, i.e. the pressure with which the release agent is dispensed, or the pressure prevailing in the distribution line 29, is approximately 1 bar to 3 bar.

[0178] For example, a volume flow of 50 ml / min to 600 ml / min, in particular between 80 ml / min and 500 ml / min, can be dispensed per release agent nozzle 61.

[0179] For a 6 m long nozzle bar 63, the total volume flow of the release agent can be, for example, between 1 l / min and 6 l / min. Since this value depends on the width of the system or the width of the counter roll 28, the volume flow of the release agent can be approximately 0.15 l / min to 1 l / min per meter of length of the nozzle bar 63. The release agent preferably comprises silicone oil and water. In all embodiments, the release agent can comprise, for example, between 5% and 20% silicone oil. For example, the release agent can comprise between 95% and 80% of a diluent, in particular water.

[0180] The release agent preferably has a viscosity according to ISO 3219 of approximately 150 mPAs to 250 mPAs.

[0181] A coolant nozzle 38 may also be provided, which can be used to provide the surface of the compression belt 26 with a coolant.

[0182] 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 the upsetting device (21) comprises a rotating cloth (26), a counter-roller (28) and an upsetting gap (30) formed between the cloth (26) and the counter-roller (28), - wherein the compression device (21) has a compression mode in which it is operated such that the fibrous web runs through the compression gap (30) at production speed and is conveyed there between the moving cloth (26) and the moving counter-roller (28) and is thereby compressed in the machine running direction (1), - wherein a release agent dispensing arrangement (36) with release agent nozzles (61) is provided for dispensing a release agent onto the outer surface of the counter roll (28), characterized in that - that the release agent nozzles (61) have synchronously operated nozzle valves (62) for the discontinuous, pulsed discharge of the release agent.

2. Upsetting device (21) according to claim 1, characterized in that a nozzle bar (63) is provided which runs parallel to the axis of rotation of the counter-roller (28), along the course of which the nozzles are arranged, and in that the nozzles discharge the separating agent over the entire width of the counter-roller (28).

3. Upsetting device (21) according to claim 1 or 2, characterized in that - that the nozzle valves (62) have a clock frequency, i.e. a frequency of the release agent outputs per second, of 10Hz to 30Hz, preferably of 15Hz to 25Hz, - in particular that the nozzle valves (62) have an adjustable clock frequency of 10Hz to 30Hz, preferably of 15Hz to 25Hz.

4. Upsetting device (21) according to one of claims 1 to 3, characterized in that - that the nozzle valves (62) have an adjustable opening duration of the individual pulses of the release agent expenditure, - in particular that the opening duration of the nozzle valves (62) per pulse is between 400ps and 1200ps, in particular between 500ps and 1000ps.

5. Upsetting device (21) according to one of claims 1 to 4, characterized in that the nozzle pressure, in particular the pressure which the release agent has in the area immediately in front of the release agent nozzle (61), is between 1 bar and 3 bar.

6. Upsetting device (21) according to one of claims 1 to 5, characterized in that - that the volume flow of the release agent per release agent nozzle (61) is between 50 ml / min and 600 ml / min, preferably between 80 ml / min and 500 ml / min, - and / or that the total volume flow of the release agent, depending on the length of the nozzle bar (63), is between 0.151 / min and 11 / min per meter of length of the nozzle bar (63), - in particular that the total volume flow for a 6m long nozzle bar (63) is between 11 / min and 61 / min.

7. Upsetting device (21) according to one of claims 1 to 6, characterized in that - that the release agent contains silicone oil, - in particular that the release agent comprises silicone oil and water, - in particular that the release agent comprises between 5% and 20% silicone oil and between 95% and 80% water, - in particular that the release agent comprises 10% silicone oil and 90% water, - and preferably, the release agent has a viscosity according to ISO 3219 of 150mPAs to 250m PAs and in particular of 200m PAs.

8. Upsetting device (21) according to one of claims 1 to 7, characterized in that a mixing container (67) is provided for mixing the components of the release agent, in particular for mixing water and silicone oil.

9. Upsetting device (21) according to one of claims 1 to 8, characterized in that a pressure vessel (68) is provided in which the release agent is provided under excess pressure for dispensing through the release agent nozzles (61).

10. Upsetting device (21) according to one of claims 1 to 9, characterized in that the nozzle bar (63) comprises a distribution line (69) which distributes the separating agent to several or all nozzles.

11. Upsetting device (21) according to one of claims 1 to 10, characterized in that a scraper (37) is provided which scrapes the release agent dispensed by the release agent dispensing arrangement (36) from the counter roller (28).

12. Upsetting device (21) according to one of claims 1 to 11, characterized in that an adjusting device (39) is provided for displacing the wrap roller (34) and thereby for adjusting the wrap angle (35).

13. Upsetting device (21) according to claim 12, characterized in that the adjusting device (39) is designed such that - that the wrap angle (35) of the cloth (26) 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) can be adjusted between 15° and 90°, preferably between 20°-60°.

14. Upsetting device (21) according to one of claims 12 or 13, 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.

15. Upsetting device (21) according to one of claims 1 to 14, characterized - 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.

16. Upsetting device (21) according to one of claims 1 to 15, characterized in that - that the compression device (21) comprises a pressure bar (33) for pressing the cloth (26) towards or against the counter roller (28), - and that the pressure bar (33) 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 45 kN / m to 70 kN / m towards the counter-roller (28).

17. Upsetting device (21) according to one of claims 1 to 16, 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.

18. Upsetting device (21) according to one of claims 1 to 17, 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.

19. 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.

20. Plant according to claim 19, 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).

21. Method for operating a compression device (21), in particular a Clupak device, for compressing a fibrous web of a plant for producing kraft paper, - wherein the upsetting device (21) comprises a rotating cloth (26), a counter-roller (28) and an upsetting gap (30) formed between the cloth (26) and the counter-roller (28), - wherein the compression device (21) is operated in a compression mode such that the fibrous web runs through the compression gap (30) at production speed and is conveyed there between the moving cloth (26) and the moving counter-roller (28) and is thereby compressed in the machine running direction (1), - wherein a release agent dispensing arrangement (36) with release agent nozzles (61) dispenses a release agent onto the outer surface of the counter roll (28), characterized in that - that the release agent is discharged discontinuously, in pulsed fashion, through the nozzles via synchronously operated nozzle valves (62).

22. Method according to claim 21, characterized in that the separating agent is discharged over the entire width of the counter-roller (28) via a nozzle bar (63) running parallel to the axis of rotation of the counter-roller (28), along the course of which the nozzles are arranged.

23. Method according to claim 21 or 22, characterized in that - that the nozzle valves (62) have a clock frequency, i.e. a frequency of the release agent outputs per second, of 10Hz to 30Hz, preferably of 15Hz to 25Hz, - in particular that the nozzle valves (62) have an adjustable clock frequency of 10Hz to 30Hz, preferably of 15Hz to 25Hz.

24. Method according to one of claims 21 to 23, characterized in that - that the nozzle valves (62) have an adjustable opening duration of the individual pulses, - in particular that the opening duration of the nozzle valves (62) per pulse is between 400ps and 1200ps, in particular between 500ps and 1000ps.

25. Method according to one of claims 21 to 24, characterized in that the nozzle pressure, i.e. the pressure with which the release agent is dispensed, is between 1 bar and 3 bar.

26. Method according to one of claims 21 to 25, characterized in that - that the volume flow per nozzle is between 50ml / min and 600ml / min, preferably between 80ml / min and 500ml / min, - and / or that the total volume flow for a 6m long nozzle bar is between 11 / min and 61 / min.

27. Method according to one of claims 21 to 26, characterized in that - that the release agent contains silicone oil, - in particular that the release agent comprises silicone oil and water, - in particular that the release agent comprises 10% silicone oil and 90% water, - and preferably, the release agent has a viscosity according to ISO 3219 of 150mPAs to 250m PAs and in particular of 200m PAs.

28. Method according to one of claims 21 to 27, characterized in that the release agent is mixed in a mixing container (67), in particular for mixing water and silicone oil.

29. Method according to one of claims 21 to 28, characterized in that the release agent is pressurized in a pressure vessel (68) and is made available for discharge through the nozzles.

30. Method according to one of claims 21 to 29, characterized in that the separating agent is distributed to several or all nozzles via a distribution line (69).

31. Method according to one of claims 21 to 30, characterized in that a scraper (37) is provided which scrapes the release agent dispensed by the release agent dispensing arrangement (36) from the counter roller (28).

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