[go: up one dir, main page]

WO2025160610A1 - Procédé de production de papier kraft - Google Patents

Procédé de production de papier kraft

Info

Publication number
WO2025160610A1
WO2025160610A1 PCT/AT2025/060030 AT2025060030W WO2025160610A1 WO 2025160610 A1 WO2025160610 A1 WO 2025160610A1 AT 2025060030 W AT2025060030 W AT 2025060030W WO 2025160610 A1 WO2025160610 A1 WO 2025160610A1
Authority
WO
WIPO (PCT)
Prior art keywords
roller
fibrous web
drying
counter
cloth
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/AT2025/060030
Other languages
German (de)
English (en)
Inventor
Roland Scheiflinger
Christian GERNIG
Georg BACOSKY
Harald Meysel
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mondi AG
Original Assignee
Mondi AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mondi AG filed Critical Mondi AG
Publication of WO2025160610A1 publication Critical patent/WO2025160610A1/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F1/00—Wet end of machines for making continuous webs of paper
    • D21F1/18—Shaking apparatus for wire-cloths and associated parts
    • D21F1/20—Shaking apparatus for wire-cloths and associated parts in Fourdrinier machines
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F11/00—Processes for making continuous lengths of paper, or of cardboard, or of wet web for fibre board production, on paper-making machines
    • D21F11/02—Processes for making continuous lengths of paper, or of cardboard, or of wet web for fibre board production, on paper-making machines of the Fourdrinier type
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H25/00—After-treatment of paper not provided for in groups D21H17/00 - D21H23/00
    • D21H25/005—Mechanical treatment

Definitions

  • the present invention relates, in one aspect, to a method for producing kraft paper.
  • the invention particularly relates to kraft paper as such, a kraft paper production plant, and various individual plant components.
  • 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.
  • one object of the present invention is to create a process and a system that can produce kraft paper with an improved property profile compared to the prior art and/or enables improved efficiency in the production of kraft paper.
  • a plant for producing kraft paper various plant parts, and components thereof.
  • these include a wire section with a shaking device, an upsetting device with a cloth drive, an upsetting device with an adjustment device, an upsetting device with an emergency running function, an upsetting device with a bypass arrangement, an upsetting device with a release agent dispensing arrangement, a drying section with a contact drying section, a drying section with an impact drying section, and an embossing station.
  • an upsetting device and/or an embossing station may be present with one or more of the features described here, may be omitted, or may be of conventional design.
  • a wire section and/or a dryer section may be present with one or more of the features described here or may be of conventional design.
  • a method for producing kraft paper comprising various process steps. In particular, these are shaking the fibrous web in a wire section, compressing (drying the fibrous web in a compressing device with a cloth drive), compressing (drying the fibrous web in a compressing device with an adjustment device), compressing (drying the fibrous web in a compressing device with an emergency running function), compressing (drying the fibrous web in a compressing device with a bypass arrangement, compressing (drying the fibrous web in a compressing device with a release agent dispensing arrangement), drying the fibrous web in a drying section with a contact drying section, drying the fibrous web in a drying section with an impact drying section, and embossing the fibrous web in an embossing station.
  • the fibrous web can be treated by upsetting and/or embossing according to one or more of the process steps described here; if appropriate, this step can also be omitted or carried out conventionally.
  • the shaking and/or drying of the fibrous web can be carried out using one or more of the process steps described here or can be carried out conventionally.
  • the invention relates to a process for producing kraft paper comprising the following steps:
  • the wire section comprises a continuously rotating dewatering wire and the application of the fiber suspension to the outside of the dewatering wire takes place in the region of a breast roll of the wire section, wherein the wire section has a first dewatering section in which a first dewatering device dewatering the fiber web from below is arranged on the inside of the dewatering wire.
  • the shaking device causes the dewatering screen to oscillate in the transverse direction in the region of the breast roll, that a second dewatering section is arranged following the first dewatering section in the running direction of the fibrous web, in which second dewatering section a second dewatering device is provided which dewaters the fibrous web from above, and that the consistency of the fiber suspension applied to the screen section is at most 0.4%, preferably at most 0.3%, more preferably between 0.15% and 0.3%.
  • the dewatering screen is designed to oscillate in the area of the breast roller with an amplitude of at least 15 mm.
  • the dewatering screen is designed to oscillate in the area of the breast roller at a frequency of between 5 Hz and 10 Hz.
  • the second dewatering device comprises at least one, in particular at least three, suction zones arranged one after the other in the running direction of the fibrous web, which are operated in particular with a vacuum of between 5 and 25 kPa.
  • an endlessly rotating top-former dewatering screen is guided in the second dewatering section between the second dewatering device and the fibrous web.
  • the production speed shall be greater than 400 m/min and the width of the fibrous web shall be greater than 3.5 m and in particular greater than 5.5 m.
  • the extensibility of the paper web, in particular according to ISO 1924-3:2005, in the transverse direction is greater than 6.5%, preferably greater than 7.5%, and that the difference in the extensibility of the paper web in the transverse direction between the edge region and the central region of the paper web is a maximum of 1.5%.
  • the fibre material shall be unbleached pulp.
  • the pulp shall be made from softwood long fibres with an average fibre length of at least 2 mm in accordance with ISO 16065-2:2014.
  • the fiber material has a kappa number of at least 30, in particular of at least 45, preferably of at least 50.
  • the speed of the dewatering wire of the wire section is intended to be between 97% and 99% of the jet speed of the headbox.
  • the Ambertec formation of the paper web shall be no more than 0.7 (g/m 2 ).
  • the Gurley drag of the paper web in particular in accordance with ISO 5636-5:2013, is intended to be no more than 15 s, preferably no more than 10 s.
  • the tensile energy absorption index of the paper web in the transverse direction is at least 2.5 J/g, preferably at least 3.0 J/g.
  • the drying section comprises a pre-drying section and a post-drying section, and that the fibrous web is compressed between the pre-drying section and the post-drying section by a compression device, in particular by a Clupak device.
  • the fibrous web is calendered or embossed in a calendering device or in an embossing device after the drying section.
  • the fibrous web is compressed in a compression device, wherein the compression device is designed in particular as a Clupak device.
  • a rotating cloth is driven by a cloth drive. If necessary, it is provided that a counter roller is driven by a counter roller drive.
  • 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 counter roll and is thereby compressed in the machine running direction.
  • the cloth is driven by the cloth drive in compression mode.
  • 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.
  • the drive speed of the cloth drive and the counter-roller drive can be controlled or regulated independently of each other.
  • the compression device compresses the fibrous web between the pre-drying section and the after-drying section in the machine direction.
  • the compression device compresses the fibrous web at a dry content of the fibrous web of 55% to 70%.
  • the compression device comprises a rotating cloth, a pressure bar, a wrap-around roller, a counter-roller and preferably a cloth drive roller.
  • the upsetting device is provided with an upsetting mode in which the circulating cloth is pressed by the pressure bar towards the counter roller and wraps around the counter roller at a wrap angle. If necessary, it is provided that 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.
  • the wrap angle can be changed and adjusted by moving the wrap roller using an adjusting device.
  • 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°,
  • the wrap angle can be adjusted between 15° and 90°, preferably between 20° and 60°.
  • the displacement of the wrap-around roller is compensated for with a substantially constant cloth length by displacing a compensating roller that can be displaced along a compensating path.
  • the compensating roller can be moved along the compensating path by more than 10 cm, in particular by more than 45 cm and preferably between 5 cm or 10 cm and 55 cm.
  • the compensating roller can act as a tensioning roller to tension the fabric.
  • the compensating roller is intended to be the tensioning roller for tensioning the fabric.
  • the fibrous web emerging from the compression gap or leaving the counter roll is guided or deflected by a guide roller arranged downstream of the counter roll along the machine running direction. If necessary, it is provided that the guide roller can be moved to change the paper web wrap angle of the fiber web around the counter roller.
  • the cloth is guided in the compression mode by the wrap roller and the pressure bar at a wrap angle around the counter roller.
  • the adjustment device changes or can change the position of the wrap roller and thus the wrap angle in or during the compression mode and preferably at production speed.
  • 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 45 kN/m to 70 kN/m towards the counter roll.
  • the counter roll is heated in the compression mode.
  • 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.
  • the compression device can optionally be operated in a compression mode in which the rotating cloth is pressed by the pressure bar towards the counter roll and wraps around the counter roll by a wrap angle, wherein in the compression mode a compression gap is formed between the cloth and the counter roll, which gap is designed to convey the fibrous web through at production speed and thereby compress it in the machine direction.
  • the upsetting device can be operated in an emergency mode in which the pressure bar is retracted compared to the upsetting mode so that a gap is formed between the cloth and the counter roller.
  • the distance is preferably greater than 5mm. If necessary, the separation time in emergency mode, i.e., the time required to create a gap between the fabric and the counter roll from the compression mode, is less than 2 seconds, preferably less than 1 second. If necessary, the position of the wrap-around roll is changed in emergency mode such that the fabric is lifted from the counter roll.
  • the tensioning roller is designed to re-tension the fabric in emergency mode and thereby lift it off the counter roller.
  • a belt break signal from a sensor for detecting a fault is processed and directly or indirectly activates the emergency operation mode.
  • the fibrous web is cut off by a cutting device in an area along the machine direction in front of the compression device before or during the emergency running mode.
  • the belt break signal is processed and directly or indirectly activates the cutting device.
  • a cloth drive is provided to drive the cloth drive roller and thus the cloth in emergency mode, even if a gap has already been formed between the cloth and the counter roller.
  • the cloth drive can or does drive the cloth preferably at a rotational speed that essentially corresponds to the production speed.
  • a counter roller drive is provided to drive the counter roller in emergency mode, even if a gap has already been formed between the cloth and the counter roller. If necessary, it is provided that the counter-roller drive can drive or drives the counter-roller preferably at a rotational speed that essentially corresponds to the production speed.
  • the pressure bar is retracted pneumatically or hydraulically in emergency mode, in particular by means of a bellows cylinder.
  • the speeds of the blanket and counter roll can be brought up to production speed without the need for the blanket to be pressed against the counter roll. This reduces wear when the swaging device starts up and extends the maintenance interval.
  • the pressure bar can be immediately moved into its retracted position, e.g. in less than 2 seconds or preferably in less than one second, thus switching the swaging device from its swaging mode to emergency mode.
  • the blanket and counter roll can continue to move preferably 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.
  • the fibrous web may optionally:
  • an upsetting device in particular a Clupak device, runs through an upsetting gap provided between a cloth and a counter-roller and is conveyed there between the moving cloth and the moving counter-roller and is thereby upset in the machine direction,
  • the method comprises the step of conveying the fibrous web by the bypass arrangement bypassing the compression device but not bypassing other parts of the system.
  • the method comprises the step of arranging the upsetting device along the machine direction between a plant part upstream of the upsetting device and a plant part downstream of the upsetting device, and conveying the fibrous web along the bypass path of the bypass arrangement from the outlet of the upstream plant part to the inlet of the downstream plant part.
  • the method comprises the step of drying the fibrous web in a pre-drying section of the drying section and in a post-drying section of the drying section arranged downstream of the pre-drying section along the machine direction.
  • the method comprises the step of arranging the compression device along the machine direction between the pre-drying section and the after-drying section.
  • the method comprises the step that the bypass arrangement conveys or can convey the fibrous web from the pre-drying section to the after-drying section, bypassing the compression device.
  • the method comprises the step of guiding a strip of the fibrous web with a cable guide either through the bypass arrangement or through the compression device.
  • the method comprises the step of a bypass cable guide of the cable guide guiding the strip of the fibrous web through or into the bypass arrangement and a compression cable guide of the cable guide guiding the strip of the fibrous web through or into the compression device.
  • the method comprises the step of providing the bypass cable guide and the compression cable guide permanently or simultaneously next to each other, but only selectively guiding the strip of the fibrous web.
  • the method comprises the step of the bypass cable guide guiding the strip through or into the bypass arrangement with a first pair of cables, in particular with a first cable and a second cable.
  • the method comprises the step of the compression cable guide guiding the strip through or into the compression device with a second pair of cables, in particular with a third cable and a fourth cable.
  • the method comprises the step of the rope guide guiding the strip into the downstream component of the system, following the bypass rope guide and following the compression rope guide, in a section with another pair of ropes.
  • the method comprises the step of driving the ropes by one or more rope drives, and in particular by a first rope drive and a second rope drive.
  • the method comprises the step of the first rope drive driving one rope of the first rope pair and one rope of the second rope pair.
  • the method comprises the step of the second rope drive driving the other rope of the first rope pair and the other rope of the second rope pair.
  • the method comprises the step of the first rope drive driving the second rope and the third rope and the second rope drive driving the first rope and the fourth rope.
  • the method comprises the step of the bypass arrangement conveying the fibrous web at production speed, wherein the production speed is greater than 400 m/min, in particular greater than 600 m/min.
  • the method comprises the steps of producing a first type of kraft paper when the fibrous web passes through the upsetting device,
  • 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.
  • the method comprises the step of discharging the release agent discontinuously in a pulsed manner through the nozzles via synchronously operated nozzle valves.
  • 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.
  • the drying section comprises a drying section having a contact drying area arranged in the machine direction upstream of an impact drying area, wherein at least two, in particular three, drying cylinders arranged one after the other in the machine direction are provided in the contact drying area.
  • a separate and endlessly rotating drying fabric is provided for each drying cylinder, which follows the outer circumference of the respective drying cylinder in a contact area, and the drying fabric presses the fibrous web against the outer circumference of the drying cylinder.
  • the length of a tensile path can in particular be the distance that the fibrous web travels between the end of one pressing area and the beginning of a subsequent pressing area.
  • drying takes place in a pre-drying section and in a post-drying section, and that the drying section is arranged in the post-drying section or forms the post-drying section.
  • the fibrous web has a dry content of at least 55 wt.%, in particular of at least 65 wt.%, upon entering the drying section and/or that the fibrous web has a dry content of at most 95 wt.%, in particular of at most 85 wt.%, upon leaving the drying section.
  • the rotation speed of the first drying cylinder in the machine direction of the contact drying area is lower, in particular up to 7% lower, than the movement speed of the fibrous web entering the drying section.
  • the rotational speed of the second drying cylinder in the machine direction of the contact drying area is greater, in particular by up to 0.15% greater, than the movement speed of the fibrous web between the first and second drying cylinders, and/or that the rotational speed of the third drying cylinder in the machine direction of the contact drying area is greater, in particular by up to 0.10% greater, than the movement speed of the fibrous web between the second and third drying cylinders.
  • the rotation speed of the cylinder roller of an impact drying device directly following the contact drying area of the impact drying area is greater than or equal to the movement speed of the fibrous web leaving the contact drying area, whereby the speed difference is in particular between 0% and 0.10%.
  • the drying section comprises an impact drying area which has at least one impact drying section, in particular three impact drying sections, wherein each impact drying section is delimited in the machine direction before and after by a drying cylinder to which a drying wire is assigned, which follows the outer circumference of the drying cylinder in a pressing area and in particular presses a fibrous web passing through the drying section against the drying cylinder.
  • the fibrous web passes through a free shrinking section in the impact drying section, which is arranged between the exit of the pressing area arranged upstream in the machine direction and the entrance of the pressing area arranged downstream in the machine direction, wherein the free shrinking section has a length of at least 15.0 m.
  • the running speed of the fibrous web shall be at least 600 m/min.
  • cylinder rollers in the impact drying section are heated to a temperature of at least 110°C.
  • drying hoods in the impact drying section are heated to a temperature of at least 160°C, if necessary up to 400°C.
  • the fibrous web has a dry content of at least 55 wt.%, in particular of at least 65 wt.%, when entering the drying section and/or that the fibrous web has a dry content of at least 55 wt.%, in particular of at least 65 wt.%, when leaving the drying section from the drying section has a dry matter content of not more than 95% by weight, in particular not more than 85% by weight.
  • the fibrous web is embossed in an embossing station after drying in the drying section. If appropriate, the fibrous web has a dry matter content of at least 85% by weight upon entering the embossing station.
  • the fibrous web is provided with an embossed structure during embossing, which is formed from an arrangement of embossments, wherein the embossments have a height of at least 0.1 mm, in particular of between 0.1 mm and 2 mm.
  • the indentations may have a rectangular, spherical segment, pyramid or prism geometry.
  • adjacent indentations are spaced from one another by a flat section of the fibrous web, wherein the distance between adjacent indentations in the machine direction of the fibrous web is at least 0.5 mm, in particular between 0.5 mm and 5.0 mm, and/or wherein the distance between adjacent indentations in the transverse direction of the fibrous web is at least 0.5 mm, in particular between 0.5 mm and 5.0 mm.
  • the embossing station may comprise an embossing roller, the embossing roller being provided with an embossing profile on its surface.
  • the embossing profile of the embossing roller is cleaned, in particular during embossing, by means of a cleaning brush, wherein a cleaning agent, in particular a water-air mixture, is applied to the embossing profile.
  • a cleaning agent in particular a water-air mixture
  • the cleaning brush rotates about a rotation axis aligned substantially parallel to the rotation axis of the embossing roller, and/or that the cleaning brush is moved back and forth substantially parallel to the rotation axis of the embossing roller.
  • the surface temperature of the embossing roller during embossing is between 20°C and 100°C.
  • the invention relates to a plant for producing kraft paper comprising the following plant components:
  • the wire section comprises an endlessly rotating dewatering wire, on the outside of which a fiber suspension can be applied in the area of a breast roll, wherein the wire section has a first dewatering section in which a first dewatering device for dewatering the fiber web from below is arranged on the inside of the dewatering wire.
  • a shaking device is provided in the wire section, which is designed to cause the breast roll to oscillate transversely to the running direction of the dewatering wire, and that a second dewatering section is arranged following the first dewatering section in the running direction of the dewatering wire, in which a second dewatering device for dewatering the fibrous web from above is provided on the outside of the dewatering wire.
  • a second dewatering device for dewatering the fibrous web from above is provided on the outside of the dewatering wire.
  • in the second dewatering section on the inside of the dewatering screen at least four transversely extending formation strips are provided, which are designed to exert a pressure of between 2 and 25 kPa on the dewatering screen in the direction of the second dewatering device.
  • the second dewatering device comprises at least one, in particular at least three, suction zones arranged one after the other in the running direction of the dewatering screen, which can be operated in particular with a vacuum of 5 - 25 kPa.
  • an endlessly rotating top former dewatering screen is arranged in the second dewatering section between the second dewatering device and the dewatering screen.
  • the invention also relates to a kraft paper obtained from or obtainable from a process according to the invention.
  • the system comprises a compression device, in particular a Clupak device, for compressing the fibrous web.
  • 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.
  • the compression device is designed to compress the fibrous web at a dry content of the fibrous web of 55% to 70%.
  • the compression device comprises a rotating cloth, a cloth drive driving the cloth, a counter roll, a counter roll drive driving the counter roll and a compression gap.
  • 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.
  • the cloth is or will be driven by the cloth drive in the compression mode.
  • 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.
  • the drive speed of the cloth drive and the counter-roller drive can be controlled or regulated independently of each other.
  • 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.
  • a cloth drive roller 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.
  • the two drives each provide more than 25% of the required drive power.
  • the two drives provide approximately 50% of the required drive power.
  • a tensioning roller is provided to tension the fabric in compression mode.
  • 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.
  • the upsetting device has a free-running mode as an alternative to the upsetting 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.
  • both the fabric and the counter roller are driven by the fabric drive, and the counter roller is driven by the counter roller drive.
  • the pressure bar is pressed in the compression mode with a force of at least 5 kN/m, in particular of at least 10 kN/m, in particular of at least 45 kN/m, preferably of 5 kN/m or 10 kN/m or 40 kN/m to 70 kN/m towards the counter roll.
  • 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.
  • 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.
  • the cloth shall have a Shore A hardness between 40 and 70, in particular between 50 and 60.
  • the counter roll is heated in compression mode.
  • 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.
  • This system has a production speed of preferably 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.
  • 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.
  • the production speed is at least 600 m/min, in particular at least 1000 m/min or at least 1100 m/min.
  • a circulating cloth Preferably, a circulating cloth, a pressure bar, a wrap-around roller, a counter roller and preferably a cloth drive roller are provided.
  • 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.
  • 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.
  • an adjusting device is provided for displacing the wrap roller and thereby for adjusting the wrap angle.
  • the compression of the fibrous web can be adjusted flexibly and precisely, in particular controlled and/or regulated.
  • 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°.
  • 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°.
  • 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.
  • 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.
  • the compensating roller acts as a tensioning roller to tension the cloth.
  • the compensating roller is the tensioning roller, in particular the only tensioning roller, for tensioning the fabric.
  • a guide roller arranged downstream of the counter roller along the machine running direction is provided for guiding or deflecting the fibrous web emerging from the compression gap or leaving the counter roller.
  • the guide roller can be moved to change the angle of wrap of the fiber web around the counter roller.
  • wrap roller is mounted on pivot bearings on both sides.
  • the adjusting device comprises means for changing and fixing the position of the pivot bearings relative to the counter roller.
  • 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.
  • the drive is a hydraulic or electromechanical drive. 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.
  • the counter roller is arranged in the area between the wrap roller and the pressure bar on the outside of the cloth.
  • the cloth is guided in compression mode by the wrap roller and the pressure bar around the counter roller at a wrap angle.
  • 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.
  • 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.
  • 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.
  • the upsetting device can be operated in an emergency mode in which the pressure bar is retracted compared to the upsetting mode so that a distance is formed between the cloth and the counter roller.
  • a bypass arrangement is provided for conveying the fibrous web along a bypass path, bypassing the compression device.
  • the fibrous web cannot be guided through the compression device due to a fault or due to maintenance work, it can be guided past the compression device in the present design using a bypass arrangement but continue to pass through other sections of the facility, in particular all other sections of the facility.
  • This special design allows the fibrous web to continue being conveyed even when the compression device is not functioning. This allows the system, with the exception of the compression device, to continue operating, and production does not have to be stopped. This eliminates the time-consuming system start-up process. Furthermore, by passing the fibrous web through the bypass arrangement past the compression device, kraft paper can be produced that has different product properties than in an operating mode in which the fibrous web passes through the compression device. For example, there are certainly paper types that do not require longitudinal compression in a compression device. These advantages can increase the efficiency of the system.
  • the bypass arrangement is provided exclusively in the area of the compression device and is designed to transport the fibrous web bypassing the compression device but not bypassing other parts of the system.
  • the upsetting device is arranged along the machine direction between a system component upstream of the upsetting device and a system component downstream of the upsetting device.
  • the bypass path of the bypass arrangement preferably extends from the outlet of the upstream system component to the inlet of the downstream system component.
  • the drying section may comprise a pre-drying section and a post-drying section arranged downstream of the pre-drying section along the machine running direction.
  • the compression device is arranged along the machine direction between the pre-dryer section and the after-dryer section and that the bypass arrangement conveys or can convey the fibrous web from the pre-dryer section to the after-dryer section, bypassing the compression device.
  • the bypass arrangement is provided to include an adjustable switch for selectively conveying the fibrous web or a strip of the fibrous web through the compression device or through the bypass path.
  • the strip can be, for example, approximately 10 cm to 25 cm wide. In all embodiments, the strip should be narrower than the width of the produced paper web.
  • the switch may be designed as an adjustable suction belt or vacuum belt, for example.
  • a cable guide is provided for selectively guiding a strip of the fibrous web through the bypass arrangement or through the compression device.
  • the cable guide comprises a bypass cable guide for guiding the strip of the fibrous web through or into the bypass arrangement and a compression cable guide for guiding the strip of the fibrous web through or into the compression device.
  • bypass rope guide and the compression rope guide are provided permanently and/or simultaneously next to each other.
  • the bypass cable guide comprises a first pair of cables, in particular a first cable and a second cable, for guiding the strip through or into the bypass arrangement.
  • the compression cable guide comprises a second pair of cables, in particular a third cable and a fourth cable, for guiding the strip through or into the compression device.
  • the rope guide for guiding the strip into the downstream component of the system, has a section with a further pair of ropes following the bypass rope guide and following the compression rope guide.
  • the further rope pair is preferably formed by a rope of the first rope pair and a rope of the second rope pair, in particular by the first rope and the fourth rope.
  • one or more rope drives are provided to drive the ropes, and in particular a first rope drive and a second rope drive.
  • the first rope drive is intended to drive one rope of the first rope pair and one rope of the second rope pair.
  • the second rope drive is intended to drive the other rope of the first rope pair and the other rope of the second rope pair.
  • first rope drive is intended to drive the second rope and the third rope and the second rope drive is intended to drive the first rope and the fourth rope.
  • a movable adjusting roller is provided in the section where the bypass cable guide and the compression cable guide are brought together.
  • the adjusting roller changes the course of at least one of the ropes when it is moved in such a way that the strip of the fibrous web, depending on whether it comes from the bypass rope guide or from the compression rope guide, is guided further along the rope guide to the following system component.
  • a pulley is provided in the section where the bypass cable guide and the compression cable guide are joined. If necessary, it is provided that when the strip of the fibrous web is guided along the bypass rope guide, the third rope is looped around the deflection pulley by the adjusting pulley in such a way that it is further guided between the first rope and the fourth rope.
  • the third rope is displaced by the adjusting roller in such a way that the strip runs unhindered from the compression rope guide into the further rope guide.
  • the system can comprise a conventional upsetting device, and the bypass arrangement can, in principle, be operated with any type of upsetting device.
  • the upsetting device may have modifications necessary for redirection along the bypass path. The same applies to the process.
  • a release agent dispensing arrangement with release agent nozzles for dispensing a release agent onto the outer surface of the counter roll is provided.
  • the release agent nozzles have clocked nozzle valves for discontinuous, pulsed discharge of the release agent.
  • a nozzle bar is provided along the course of which the nozzles are arranged.
  • the nozzle bar preferably runs parallel to the rotation axis of the counter roller.
  • the nozzles are designed to dispense the release agent across the entire width of the counter roll.
  • the entire width is the width against which the fiber web rests in compression mode.
  • 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. If necessary, the nozzle valves are provided with an adjustable clock frequency of 10Hz to 30Hz, preferably of 15Hz to 25Hz.
  • the nozzle valves are provided with an adjustable opening duration for the individual pulses of the release agent outputs.
  • the opening duration of the nozzle valves per pulse is between 400ps and 1200ps, in particular between 500ps and 1000ps.
  • 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.
  • 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.
  • the total volume flow of the release agent is between 0.151/min and 11/min per meter of length of the nozzle bar.
  • the total volume flow for a 6 m long nozzle bar is between 11/min and 61/min.
  • the release agent may contain silicone oil,
  • the release agent comprises silicone oil and water
  • the release agent comprises between 5% and 20% silicone oil and between 95% and 80% water
  • the release agent comprises 10% silicone oil and 90% water
  • the release agent has a viscosity according to ISO 3219 of 150 mPAs to 250 mPAs and in particular of 200 mPAs.
  • a mixing container is provided for mixing the components of the release agent, in particular for mixing water and silicone oil.
  • a pressure vessel in which the release agent is provided under overpressure for dispensing through the release agent nozzles.
  • the nozzle bar may include a distribution line that distributes the release agent to several or all nozzles.
  • a scraper is provided which scrapes the release agent dispensed by the release agent dispensing arrangement from the counter roller.
  • the system comprises a drying section, in particular a post-drying section, for drying a fibrous web, wherein the drying section has a contact drying area arranged in the machine direction upstream of an impact drying area, wherein at least two, in particular three, drying cylinders arranged one after the other in the machine direction are provided in the contact drying area.
  • each drying cylinder which follows the outer circumference of the respective drying cylinder in a contact area.
  • a drawing section is provided between the drying cylinders, in particular between two drying cylinders arranged directly one after the other in the machine direction, in which the fibrous web is exposed.
  • the fibrous web along the drawing path is not in contact with the outer circumference of a drying cylinder and/or with a drying wire
  • the length of the pulling section between two drying cylinders arranged directly one after the other in the machine direction is at least 0.5 m, in particular at least 1.0 m, preferably between 1.0 m and 2.0 m.
  • the wrap angle of the drying fabric in the contact area on the respective drying cylinder is at least 100°, in particular at least 140°.
  • a separate drive device is provided for each drying cylinder of the contact drying area, wherein the drive devices are in particular separately controllable and/or adjustable, and/or that a separate heating device is provided for each drying cylinder of the contact drying area, wherein the heating devices are in particular separately controllable and/or adjustable.
  • drying cylinders are arranged directly one after the other in the machine running direction.
  • drying screens are guided over guide rollers, wherein at least one of the guide rollers is designed as a spatially displaceable tension roller.
  • a drying screen is provided to press the fibrous web in the contact area against the outer circumference of the respective drying cylinder.
  • the drying section may comprise a pre-drying section and an after-drying section
  • the after-drying section of the plant may be a drying section having one or more of the features described herein. If necessary, it is provided that an upsetting device, in particular a Clupak device, is arranged between the pre-drying section and the after-drying section.
  • the width of the drying fabrics is smaller than the width of the fibrous web, wherein the width of the drying fabrics is in particular at least 1 m, preferably at least 2 m, smaller than the width of the fibrous web.
  • the system comprises a drying section, in particular a post-drying section, for drying a fibrous web
  • the drying section comprises an impact drying area which has at least one impact drying section, in particular three impact drying sections, wherein each impact drying section is delimited in the machine direction before and after by a drying cylinder, to which a drying fabric is assigned, which follows the outer circumference of the drying cylinder in a pressing area and in particular presses a fibrous web passing through the drying section against the drying cylinder.
  • the impact drying section is designed in such a way that a fibrous web passing through the drying section passes through a free shrinkage distance of at least 15.0 m between the exit of the pressing area arranged upstream in the machine direction and the entrance of the pressing area arranged downstream in the machine direction.
  • the impact drying section comprises at least one impact drying device, wherein an impact drying device comprises a cylindrical roller around which the fibrous web is guided, and that a drying hood is associated with the cylindrical roller, which blows hot air onto the surface of the fibrous web.
  • the impact drying section is provided free of drying screens. If necessary, it is provided that the fibrous web rests freely on the outer circumference of the cylinder rollers in the impact drying section.
  • the impact drying section comprises at least two, in particular three, impact drying devices, and that the impact drying section comprises a further drying cylinder, wherein the further drying cylinder is arranged in the machine direction between the two cylinder rollers.
  • a drying hood is assigned to the additional drying cylinder, or that the additional drying cylinder is designed without a drying hood.
  • the impact drying area follows a contact drying area in the machine direction, wherein at least two, in particular three, drying cylinders arranged one after the other in the machine direction are provided in the contact drying area, and wherein each drying cylinder is assigned an endlessly rotating drying wire which follows the outer circumference of the respective drying cylinder in a contact pressure area.
  • the drying section is intended to comprise a pre-drying section and an after-drying section, and the after-drying section of the plant is a drying section as described here.
  • an upsetting device in particular a Clupak device, is arranged between the pre-drying section and the after-drying section.
  • the system comprises an embossing station for embossing the fibrous web, which is arranged between the drying section and the winding station, in particular between the after-drying section and the winding station.
  • the embossing station comprises an embossing roller and a counter roller, wherein an embossing gap is provided between the embossing roller and the counter roller, through which the fibrous web is guided for embossing, wherein the embossing roller is equipped with an embossing profile on its surface, and wherein the counter roller has an elastic surface.
  • the embossing station may include a cleaning brush for cleaning the embossing profile of the embossing roller.
  • the embossing station may comprise an application device for applying a cleaning agent, in particular an air-water mixture, to the embossing profile of the embossing roller.
  • the cleaning brush is designed as a brush roller and has a rotation drive for rotating the cleaning brush about a rotation axis, wherein the rotation axis of the cleaning brush is arranged substantially parallel to the rotation axis of the embossing roller.
  • the cleaning brush is provided with a displacement drive for moving the cleaning brush back and forth substantially parallel to the rotational axis of the embossing roller.
  • an adjusting device is provided to adjust the rolling pressure exerted on the fibrous web in the embossing gap.
  • the invention also relates to a paper as such, in particular a kraft paper, especially a sack kraft paper.
  • a paper as such, in particular a kraft paper, especially a sack kraft paper.
  • the paper can be produced using a process disclosed here.
  • the extensibility of the kraft paper, in particular according to ISO 1924-3:2005, in the transverse direction is greater than 5%, preferably greater than 7.5%.
  • 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.
  • the width refers in particular to the dimension of a paper web in the transverse direction of the paper.
  • the difference in the extensibility of the paper in the transverse direction between the edge region and the middle region of the paper web is a maximum of 4.0%, more preferably a maximum of 3.0% and even more preferably a maximum of 1.5%.
  • the extensibility of the paper web can be between 5% and 8% in the middle and between 7.5% and 12% at the edges, depending on the manufacturing process.
  • the aforementioned difference is calculated in particular by subtracting the two extensibility values; it is therefore the absolute difference between these values. In a fictitious example of a paper web with an extensibility of 7% in the middle and 8.4% at the edges, the aforementioned difference is therefore 1.4%.
  • the edge area refers in particular to an area 50 cm wide, starting from each outer edge of the paper web.
  • the center area 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.
  • the average extensibility of the paper in the middle third of the paper web differs by less than 0.8% from the extensibility in an outer third, in particular in both outer thirds, of the paper web.
  • the paper web is fictitiously divided into three sections of equal width in the width direction. The average extensibility in each third is then determined.
  • the measurement of extensibility is carried out in particular between 0.75 h and 1.5 h, typically 1.0 h, after the production of the kraft paper, i.e. after completion of the last manufacturing step.
  • the Ambertec formation of the paper shall be a maximum of 0.7 (g/m 2 ).
  • 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.
  • the tensile energy absorption index of the paper in the machine direction 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.
  • the fiber contained in the paper may be unbleached pulp.
  • 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.
  • the fiber contained in the paper has a kappa number of at least 30, in particular of at least 40, preferably of at least 50.
  • the fibre material shall be unbleached pulp.
  • the pulp shall be made from softwood long fibres with an average fibre length of at least 2 mm in accordance with ISO 16065-2:2014.
  • the paper has an embossed structure formed from an arrangement of impressions, wherein the impressions have a height of at least 0.1 mm, in particular of between 0.1 mm and 2 mm.
  • the indentations may have a rectangular, spherical segment, pyramid or prism geometry.
  • adjacent impressions are intended to be directly adjacent to one another in the machine direction and in the cross direction of the paper.
  • adjacent impressions are spaced from one another by a flat section of the paper, wherein the distance between adjacent impressions in the machine direction of the paper is at least 0.5 mm, in particular between 0.5 mm and 5.0 mm, and/or wherein the distance between adjacent impressions in the transverse direction of the paper is at least 0.5 mm, in particular between 0.5 mm and 5.0 mm.
  • the paper may have dry-stamped imprints.
  • the paper may have an extensibility according to ISO 1924-3:2005 in the transverse direction and optionally also in the machine direction of greater than 5%, preferably greater than 7.5%.
  • the indentations shall be pyramid-shaped with a rectangular base.
  • the embossings are arranged in embossing rows, wherein the embossing rows run in the transverse direction of the kraft paper or at an angle of up to 5° to the transverse direction of the kraft paper.
  • embossings of embossing rows adjacent in the machine direction of the kraft paper have an offset in the transverse direction of the kraft paper.
  • a wire section for a plant for producing kraft paper is disclosed, having one or more of the features described here.
  • a compression device in particular a Clupak device, for a plant for producing kraft paper, having one or more of the features described here is disclosed.
  • a drying section in particular an after-drying section, for a plant for producing kraft paper, having one or more of the features described here is disclosed.
  • an embossing station for a plant for producing kraft paper having one or more of the features described here.
  • Fig. 1a-c is a schematic overall view of a kraft paper manufacturing plant according to a first embodiment of the invention
  • Fig. 2 is a schematic detailed view of a sieve section according to a
  • Fig. 3 is a schematic detailed view of an upsetting device according to a
  • Fig. 4 is a schematic detailed view of an upsetting device according to an embodiment
  • Fig. 5 is a schematic view of an upsetting device and a bypass arrangement according to an embodiment
  • Fig. 6 is a schematic detailed view of an upsetting device according to an embodiment
  • Fig. 7 is a schematic detailed view of a dryer section according to an embodiment
  • Fig. 8 is a schematic detailed view of a dryer section according to an embodiment
  • Fig. 9 is a schematic detailed view of a dryer section according to an embodiment
  • Fig. 10 is a schematic detailed view of an embossing station according to an embodiment of the invention.
  • Fig. 11a is a schematic side view of an embossed kraft paper
  • Fig. 11b is a schematic plan view of the kraft paper shown in Fig. 11a.
  • Fig. 1a-c show a schematic overall view of a kraft paper production plant according to one exemplary embodiment.
  • 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.
  • 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.
  • the fiber web is continuously dewatered or dried, passing successively through the aforementioned system components.
  • paper rolls 25 are formed, which can be transported away and/or fed to further processing steps.
  • the system shown here preferably includes a sensor for detecting a malfunction.
  • a sensor for detecting a malfunction.
  • a sensor can detect a sliver break or a partial sliver break of the fibrous web.
  • This sensor can generate a sliver break signal, which, for example, activates the emergency mode.
  • the system preferably comprises a cutting device 45.
  • the cutting device 45 enables the fibrous web to be cut off, i.e., completely severed.
  • This cutting device 45 is activated, for example, when the web break signal detects at least a partial web break.
  • an emergency mode can be activated.
  • the subsequent fibrous web can then be guided further through the system, in particular also further through the compression device 21, or the subsequent fibrous web can be redirected.
  • the compression device 21 is preferably operated in emergency mode.
  • 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.
  • the compression device 21 comprises a cloth 26.
  • the cloth 26 is an endless belt that is guided around several deflection rollers 59 or deflection rollers.
  • the compression device 21 preferably 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.
  • the compression 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 towards or against a counter-roller 28.
  • the counter-roller 28 has a counter-roller drive 29.
  • the counter-roller 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 counter-roller 28.
  • the compression gap 30 is delimited on one side by the counter-roller 28 and on the other side by the fabric 26.
  • 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 cloth 26 and the counter roll 28 and is thereby compressed in the machine direction 1.
  • the cloth 26 is driven by the cloth drive 27.
  • 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.
  • 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.
  • the thickness of the cloth 26 is reduced in this area.
  • the thickness of the elastically deformed cloth 26 increases again to its original thickness.
  • the cloth 26 contracts by a certain amount along its direction of movement, whereby the speed of the cloth 26 is locally reduced.
  • 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°.
  • the upsetting device 21 can be put into a free-running mode.
  • the two drives can preferably drive the fabric 26 and the counter roll 28.
  • the drive preferably occurs at a speed that essentially corresponds to the production speed.
  • 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.
  • the tension roller 32 can also keep the cloth 26 taut if necessary when the pressure bar 33 is retracted.
  • the upsetting device 21 comprises a wrap-around roller 34.
  • the wrap-around roller 34 is preferably 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 of the cloth 26 on the counter-roller 28. The greater the wrap angle, 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 around the counter-roller 28.
  • the wrap roller 34 is designed to be displaceable in order to be able to adjust or change the wrap angle.
  • the system comprises a bypass arrangement 46 for transporting the fibrous web along a bypass path 47, bypassing the compression device 21.
  • the bypass arrangement 46 is preferably provided exclusively in the area of the compression device 21 and is designed to transport the fibrous web bypassing the compression device 21 but not bypassing other parts of the system.
  • the upsetting device 21 is arranged along the machine direction 1 between a system part upstream of the upsetting device 21 and a system part downstream of the upsetting device 21.
  • the bypass path 47 of the bypass arrangement 46 extends from the outlet of the upstream system part to the inlet of the downstream system part.
  • the drying section 6 comprises a pre-drying section 19 and an after-drying section 20 arranged downstream of the pre-drying section 19 along the machine direction 1.
  • the compression device 21 is preferably arranged between the pre-drying section 19 and the after-drying section 20 along the machine direction 1.
  • the bypass arrangement 46 can transport the fibrous web from the pre-drying section 19 to the after-drying section 20, bypassing the compression device 21.
  • the bypass arrangement 46 comprises an adjustable switch 48 for selectively conveying the fibrous web or a strip of the fibrous web through the compression device 21 or through the bypass path 47.
  • the switch 48 is designed, for example, as an adjustable suction belt or vacuum belt.
  • a cable guide 49 is provided for selectively guiding a strip of the fibrous web through the bypass arrangement 46 or through the compression device 21.
  • the system preferably includes a sensor for detecting a malfunction.
  • a sensor for detecting a malfunction.
  • a sensor can detect a sliver break or a partial sliver break of the fibrous web.
  • This sensor can generate a sliver break signal, which, for example, activates the emergency mode.
  • the system preferably comprises a cutting device 45.
  • the cutting device 45 enables the fibrous web to be cut off, i.e., completely severed.
  • This cutting device 45 is activated, for example, when the web break signal detects at least a partial web break.
  • an emergency mode can be activated.
  • the subsequent fibrous web can then be guided further through the system, in particular also further through the compression device 21, or the subsequent fibrous web can be redirected.
  • the compression device 21 is preferably operated in emergency mode.
  • the system preferably comprises a bypass arrangement 46 for conveying the fibrous web along a bypass path 47, bypassing the compression device 21.
  • the bypass arrangement 46 is preferably exclusively in the area of the compression device
  • the upsetting device 21 is arranged along the machine direction 1 between a system part upstream of the upsetting device 21 and a system part downstream of the upsetting device 21.
  • the bypass path 47 of the bypass arrangement 46 extends from the outlet of the upstream system part to the inlet of the downstream system part.
  • the drying section 6 comprises a pre-drying section 19 and an after-drying section 20 arranged downstream of the pre-drying section 19 along the machine direction 1.
  • the compression device 21 is preferably arranged between the pre-drying section 19 and the after-drying section 20 along the machine direction 1.
  • the bypass arrangement 46 can transport the fibrous web from the pre-drying section 19 to the after-drying section 20, bypassing the compression device 21.
  • the bypass arrangement 46 comprises an adjustable switch 48 for selectively conveying the fibrous web or a strip of the fibrous web through the compression device 21 or through the bypass path 47.
  • the switch 48 is designed, for example, as an adjustable suction belt or vacuum belt.
  • a cable guide 49 is provided for selectively guiding a strip of the fibrous web through the bypass arrangement 46 or through the compression device 21.
  • Fig. 2 shows an enlarged view of a wire section according to one embodiment in detail.
  • the wire section according to this embodiment can be used in the plant shown in Fig. 1 to produce kraft paper.
  • the fiber suspension from the headbox 3 is 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 corresponds to the running direction 23 of the fiber web.
  • the dewatering screen 8 is continuously guided over an arrangement of several rollers, with the fiber suspension being applied in the area of the breast roll 10 of the screen section 2.
  • the dewatering screen 8 has a width of approximately 7.2 m.
  • the fiber is softwood pulp 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 65.
  • the consistency of the fiber suspension when applied to the dewatering screen 8 is approximately 0.22%.
  • the speed of the fiber suspension emerging from the headbox 3 is approximately 2% higher than the running speed of the dewatering screen 8.
  • the dewatering screen 8 has a speed of approximately 1100 m/min.
  • the high-frequency shaking device 4 is designed to oscillate the breast roll 10 and, consequently, the dewatering screen 8 in the area 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.
  • the oscillation occurs at a frequency of approximately 7 Hz and an amplitude of approximately 35 mm.
  • the fiber web enters a first dewatering area 11.
  • the fiber 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 initially enables a primarily gravity-driven dewatering of the fiber web, followed by a downward suction treatment.
  • the suction treatment is carried out by means of suction boxes 24.
  • the fibrous web is dewatered exclusively downwards.
  • 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.
  • 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.
  • formation bars 16 are provided, arranged one after the other in the running direction 23 of the dewatering screen 8. These form 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 is adjustable between 5 and 25 kPa.
  • the fibrous web then exits the wire section 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.
  • the resulting kraft paper Due to the treatment in the wire section, 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.
  • the kraft paper produced according to the described embodiment has the following exemplary property profile given in Table 1.
  • Fig. 3 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.
  • 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 continuously drive it.
  • the compression device 21 comprises a pressure bar 33.
  • the pressure bar 33 is designed to be displaceable and can, as in the present position, press the cloth 26 towards or against a counter roller 28.
  • the counter roller 28 has a counter roller drive 29.
  • the counter roller drive 29 and the cloth drive 27 are independently controllable or adjustable drives and preferably rotary drives.
  • Between the cloth 26 and the A compression gap 30 is formed between the counter roll 28.
  • the compression gap 30 is bounded on one side by the counter roll 28 and on the other side by the cloth 26.
  • the illustrated position of the compression device 21 essentially corresponds to the compression mode, in which the fibrous web is compressed.
  • 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.
  • the cloth 26 is driven by the cloth drive 27.
  • 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.
  • 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.
  • 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.
  • the thickness of the cloth 26 is reduced in this area.
  • the thickness of the elastically deformed cloth 26 increases again to its original thickness.
  • the cloth 26 contracts along its direction of movement by a certain amount, whereby the speed of the cloth 26 is locally reduced.
  • 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 cloth 26 and counter roller 28 can be adjusted at an angle of approximately 15°-90°, preferably between 20°-45°.
  • the upsetting device 21 can be put into a free-running mode.
  • the two drives can preferably drive the fabric 26 and the counter roll 28.
  • the drive takes place at a speed that essentially corresponds to the production speed.
  • 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.
  • the tension roller 32 can also keep the cloth 26 taut if necessary when the pressure bar 33 is retracted.
  • the upsetting device 21 comprises a wrap-around roller 34.
  • the wrap-around roller 34 is preferably 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.
  • the wrap roller 34 is designed to be displaceable in order to be able to adjust or change the wrap angle 35. 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.
  • the adjustment device 39 comprises guides or guide arms arranged on both sides of the wrap-around roller 34 and a drive. By actuating the drive, the pivot bearings for supporting the wrap-around roller 34 can be moved in a targeted manner.
  • 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 or 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.
  • 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.
  • all three movements preferably run 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°-60°.
  • 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.
  • 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.
  • the compensating roller 41 simultaneously acts as a tensioning roller 32 for tensioning the cloth 26.
  • the compensating roller 41 is the only tensioning roller 32 for tensioning the cloth 26.
  • 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.
  • a non-adjustable wrap roller 34 may be provided.
  • the compression device 21 preferably 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.
  • several silicone spray devices 36 can be provided in order to distribute the release agent over the entire width of the counter roller 28.
  • 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 via nozzle valves 62 and meter the release agent onto the counter roll 28.
  • the nozzle valves 62 are arranged side by side along a nozzle bar 63.
  • a coolant nozzle 38 may also be provided, which can be used to provide the surface of the compression belt 26 with a coolant.
  • a plurality of coolant nozzles 38 are provided to distribute the coolant over the entire width of the cloth 26.
  • Fig. 4 shows a compression device 21, in particular the compression device 21 from Fig. 3, in the emergency running mode and in particular in a position in which a distance is formed between the cloth 26 and the counter roller 28.
  • the pressure bar 33 is rapidly retracted from the compression mode, as shown, for example, by the dashed line in Fig. 3.
  • the pressure bar 33 which presses the fabric 26 toward the counter roller 28 during compression operation, enables the fabric 26 to be lifted from the counter roller 28 by its retraction.
  • the pressure bar 33 can be retracted, for example, pneumatically or hydraulically in the emergency mode.
  • a bellows cylinder can be provided as the actuator, which acts on the pressure bar 33, for example, via a pivoting lever and/or a guide.
  • the wrap roller 34 can also be moved to enable or accelerate the lifting of the cloth 26 from the counter roller 28.
  • the adjustment can be carried out via the schematically illustrated adjustment device 39, with which the wrap angle 35 can also be changed and adjusted by moving the wrap roller 34.
  • the wrap roller 34 is opposite the operating mode of Fig. 2.
  • the distance between the cloth 26 and the counter roller 28 can also be adjusted exclusively by displacing the pressure bar 33. This is particularly advantageous for upsetting devices that have a rigid wrap-around roller 34 with a non-displaceable axis.
  • the tensioning roller 32 of the upsetting device is preferably also displaced in emergency mode.
  • the tensioning roller 32 is the roller that holds the fabric 26 at the desired tension in upsetting mode. With a displaceable wrap-around roller 34, this tensioning roller 32 can simultaneously serve as a compensating roller 41.
  • the tensioning roller 32 is also preferably displaced quickly in emergency mode, so that the fabric 26 is lifted from the counter roller 28 through the interaction of the retraction of the pressure bar 33 and the displacement of the tensioning roller 32. If there is a displaceable wrap-around roller 34, this can also occur in conjunction with the displacement of the wrap-around roller 34.
  • the cloth 26 can, if necessary, be driven further in rotation.
  • a cloth drive 27 and a cloth drive roller 31 are provided.
  • the cloth 26 can thus be driven in rotation, even though a distance is provided between the counter roller 28 and the cloth 26 and even though the counter roller 28 can no longer drive the cloth 26.
  • the counter roller 28 is also driven in rotation by a counter roller drive 29.
  • the cloth 26 and the counter roller 28 therefore preferably each have a drive, wherein the two drives can drive the cloth 26 and the counter roller 28 independently of one another.
  • the rotational speed of the cloth 26 and the rotational speed of the counter roller 28 can be maintained or adjusted, even if a distance is provided between the cloth 26 and the counter roller 28.
  • the rotational speeds of the cloth 26 and the counter roller 28 can essentially correspond to the production speed.
  • the production speed is preferably greater than 400 m/min and in particular greater than 600 m/min.
  • the emergency mode is preferably triggered by a signal.
  • This signal can be a signal triggered by a person or another signal, such as a belt break signal from a sensor for detecting a malfunction.
  • the system includes a sensor that can detect a belt break or a partial belt break of the fibrous web. This sensor is preferably located upstream of the compression device 21 in the machine direction 1.
  • Fig. 5 shows a schematic side view of components of the system, and in particular the bypass arrangement 46 and the cable guide 49.
  • the bypass arrangement 46 enables the fibrous web produced on the system to be guided either through the compression device 21 or through the bypass arrangement 46.
  • the fibrous web is guided along a bypass path 47 past the compression device 21.
  • the fibrous web runs through all parts of the system with the exception of the compression device 21.
  • the fibrous web cannot be conveyed through the compression device 21 for safety reasons, but usually also for technical reasons.
  • the fibrous web is guided past the compression device 21 by the bypass arrangement 46.
  • the present design can produce paper that has not been compressed in the longitudinal direction by the compression device 21. This paper generally has different properties than paper compressed in the compression device 21. However, the paper produced without the compression device 21 can still be used as a product. If the fibrous web is to be guided through the bypass arrangement 46 instead of through the compression device 21, the following procedure can be followed: The fibrous web is preferably cut off by a cutting device 45 (see Fig. 1b).
  • a narrow strip of the fibrous web is guided towards the compression device 21 and bypass arrangement 46.
  • the narrow strip can be, for example, approximately 10 cm to 25 cm wide.
  • a switch 48 is actuated.
  • This switch 48 can, for example, be designed as a suction belt or a vacuum belt and can be adjusted so that the course or direction of the strip of fibrous web can be changed.
  • the switch 48 directs the strip into a cable guide 49.
  • the cable guide 49 includes a bypass cable guide 51 that can guide the strip along the bypass path 47. Furthermore, the cable guide 49 includes a compression cable guide 52 that guides the strip into or through the compression device 21. The strip can then be inserted through the switch 48 either into the bypass cable guide 51 or the compression cable guide 52.
  • the cable guide can be designed, for example, as follows: A first cable 53 and a second cable 54 run along the compression cable guide 52, starting from the switch 48. The first cable 53 and the second cable 54 run directly adjacent to one another in the direction of the compression device 21 and form the compression cable guide 52 in this area. However, the first cable 53 and the second cable 54 do not run through the compression gap 30 of the compression device 21, but rather laterally past the compression device 21. At the exit of the compression gap 30, the strip is in turn conveyed further by the compression cable guide 52 in the direction of the downstream machine component.
  • the strip is guided by the first cable 53 and a fourth cable 56, which run directly adjacent there.
  • the bypass rope guide 51 comprises, in the area after the switch 48, a third rope 55 and the fourth rope 56.
  • the third rope 55 and the fourth rope 56 run in this Area immediately adjacent to each other and guide the strip along the bypass path 47 through the bypass arrangement 46.
  • the cable guide 49 is formed by the first cable 53 and the fourth cable 56 in the present embodiment.
  • the bypass cable guide 51 can comprise a first pair of cables, in particular the first cable 53 and the second cable 54. This first pair guides the strip of fibrous web along the bypass path 47.
  • the compression cable guide 52 can comprise a second pair of cables, in particular the third cable 55 and the fourth cable 56. This second pair guides the strip of fibrous web through or into the compression device 21.
  • the cable guide 49 has a section adjacent to the bypass cable guide 51 and adjacent to the compression cable guide 52 running parallel thereto, in which the strip of the fibrous web is guided by a cable of the first cable pair and a cable of the second cable pair.
  • the strip is guided in this area by the first cable 53 and the fourth cable 56.
  • the cables 53, 54, 55, 56 are preferably all designed as endless, circular cables in all embodiments.
  • one or more cable drives 57, 58 are provided to drive the cables 53, 54, 55, 56.
  • a first cable drive 57 and a second cable drive 58 are provided.
  • the first cable drive 57 drives the second cable 54 and the third cable 55.
  • the second cable drive 58 drives the first cable 53 and the fourth cable 56.
  • a drive drives a rope of the first rope pair and a rope of the second rope pair.
  • another drive drives the second rope of the first rope pair and the second rope of the second rope pair.
  • An adjusting roller 60 can be provided in the section where the bypass cable guide 51 and the compression cable guide 52 converge. As shown in the enlarged detail, the adjusting roller 60, when actuated, shifts the position of at least one of the cables 53, 54, 55, 56 such that the strip of fibrous web, depending on whether it comes from the bypass cable guide 51 or the compression cable guide 52, can be guided further along the cable guide 49 to the downstream system component.
  • a deflection pulley 59 is provided in this area. If the strip of fibrous web is guided along the bypass cable guide 51, the third cable 55 is looped around the deflection pulley 59 by the adjusting pulley 60 such that it is guided further between the first cable 53 and the fourth cable 56. If, however, the strip of fibrous web emerges from the compression cable guide 52, the adjusting pulley 60 can displace a portion of the third cable 55 such that the strip can run unhindered from the compression cable guide 52 into the further cable guide 49. In particular, a loop of the third cable 55 is retracted by the adjusting pulley 60.
  • Fig. 6 shows a schematic structure of a possible embodiment of a release agent dispensing arrangement 36.
  • 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 comprises a release agent source 66, from which the release agent component, for example, a silicone oil, is provided.
  • the release agent component for example, a silicone oil
  • Viscosity must be provided in a tank or from a source.
  • the diluent and the release agent component can be mixed in a mixing tank 67.
  • the mixing tank 67 is equipped with a circulation pump and/or a mixer to ensure uniform mixing of the release agent components.
  • 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.
  • 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.
  • the release agent nozzles 61 are operated in a cyclical manner by the nozzle valves 62.
  • the release agent is discharged discontinuously and in pulsed fashion through the release agent nozzles 61.
  • the special, timed output 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.
  • 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.
  • 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.
  • Dosing can be carried out in particular by a control system and a pulse width modulation effected by the control system.
  • 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.
  • 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.
  • the total volume flow of the release agent can be 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 the nozzle bar 63 length.
  • the release agent preferably comprises silicone oil and water.
  • the release agent may, for example, comprise between 5% and 20% silicone oil.
  • the release agent may comprise between 95% and 80% of a diluent, in particular water.
  • the release agent preferably has a viscosity according to ISO 3219 of approximately 150 mPAs to 250 mPAs.
  • a coolant nozzle 38 may also be provided, which can be used to apply a coolant to the surface of the compression belt 26.
  • several coolant nozzles 38 are provided to distribute the coolant across the entire width of the fabric 26.
  • Fig. 7 shows an enlarged view of a dryer section according to one embodiment in detail. The dryer section according to this embodiment can be used in the plant shown in Fig. 1 to produce kraft paper.
  • the dryer section shown here comprises a contact drying area 70, followed by an impact drying area 71.
  • the contact drying area 70 contains three steam-heated drying cylinders 72, over which the incoming fiber web 81 is guided.
  • the drying cylinders 72 are arranged directly one after the other.
  • each drying cylinder 72 is assigned its own drying wire 73, which is designed as a belt that presses the fibrous web 81 against the outer circumference of the respective drying cylinder 72 in a contact area 74.
  • Each dryer fabric 73 is guided in a continuous, circular motion over a series of guide rollers 75.
  • Each of the guide rollers 75 is movable along a displacement direction 82 and thus serves as a tensioning roller 76 to adjust the tension of the dryer fabric 73 and thus the pressure with which the fibrous web 81 is pressed against the outer circumference of the drying cylinder 72.
  • the contact drying area 70 is followed by the impact drying area 71.
  • Fig. 7 only the beginning of the impact drying area 71 is shown.
  • This begins with an impact drying group comprising two impact drying devices 77.
  • Each impact drying device 77 in turn comprises a drying hood 78 and a cylindrical roller 79.
  • the fibrous web 81 which passes through an impact drying device 77, is conveyed over the cylindrical roller 79 deflected and blown with hot air through the drying hood 78 and thus subjected to drying.
  • a further drying cylinder 80 can be provided, which has a drive but no drying screen.
  • This further drying cylinder 80 does not form part of the contact drying area 70 according to the invention, since it is arranged downstream of the first impact drying device 77, as seen in the machine direction 1.
  • the drying section according to this embodiment comprises two further impact drying groups, as described above.
  • FIG. 1 b A representation showing a complete drying section according to the invention, also used as a post-drying section 20, is Fig. 1 b and c.
  • the fibrous web is fed directly from the compression device 21 into the after-drying section 20, which begins with a sequence of three drying cylinders 72 with separate drying wires 73. These three drying cylinders 72 form the contact drying area 70 of the after-drying section 20 according to the invention.
  • the contact drying area 70 is followed by the impact drying area 71, which begins with a group of two impact drying devices 77 separated by another drying cylinder 80. Three such groups are provided, with an additional drying cylinder 80 provided between each two groups, each equipped with an additional drying screen.
  • the additional drying cylinders 80 are not part of the contact drying area 70.
  • Fig. 1 the dryer section shown in Fig. 1 is similar to that shown in Fig. 7.
  • the fibrous web emerging from the compression device 21 has a dry content of approximately 65% and is introduced into a post-drying section 20 designed according to the invention.
  • the rotation speed of the first drying cylinder 72 of the contact drying section 70 is lower than the speed of the incoming fibrous web.
  • the rotation speed of the second and third drying cylinders 72 in the machine direction is each higher than the speed of the fibrous web upstream of the respective drying cylinder 72, so that tension builds up.
  • the speed differences can be adjusted as required, but this generally results in a gentle tension build-up up to the impact drying area 71 and an improvement in the transverse shrinkage profile of the fibrous web.
  • the adjustment of the speed differences is made possible in particular by the separate drives of the different drying cylinders 72.
  • the rotation speed of the first cylinder roller 79 of the impact drying area 71 is greater than the movement speed of the fibrous web leaving the contact drying area 70.
  • the width of the drying screens 73 is approximately 2 m smaller than the width of the fibrous web, whereby both edge regions of the fibrous web, each with a width of approximately 1 m, are not pressed by the drying screens 73 against the surface of the drying rollers 72. This further improves the cross-sectional profile of the produced paper web.
  • the resulting kraft paper exhibits a variety of advantageous properties.
  • the kraft paper produced according to the described embodiment can exhibit the exemplary property profile listed in Table 1 above.
  • Fig. 8 shows an enlarged view of a dryer section according to one embodiment in detail.
  • the dryer section according to this embodiment can be used in the plant shown in Fig. 1 to produce kraft paper.
  • the dryer section shown here comprises a contact drying area 70, followed by an impact drying area 71. Only the last part of the contact drying area 70 is shown in Fig. 8.
  • the impact drying area 71 comprises three impact drying sections 83, also referred to as impact drying groups, each of which comprises two impact drying devices 77.
  • Each impact drying device 77 in turn comprises a drying hood 78 and a cylindrical roller 79 associated with this drying hood 78.
  • the fibrous web 81 which passes through an impact drying device 77, is deflected by the cylindrical roller 79 and subjected to hot air blown by the drying hood 78, thereby undergoing a drying process.
  • the cylindrical roller 79 is heated, so that the moisture escaping from the fibrous web 81 creates a gas cushion, whereby the fibrous web 81 is, at least in sections, not in direct contact with the outer surface of the cylindrical rollers 79.
  • each impact drying section 83 is defined by the point at which the fibrous web 81 exits the pressing area 74, which, viewed in the machine direction 1, is located directly above or in front of the impact drying section 83.
  • each impact drying section 83 is in turn defined by the point at which the fibrous web 81 enters the pressing area 74, which, viewed in the machine direction 1, is located directly below or after the impact drying section 83.
  • the free shrink length is now the length that the fibrous web 81 has to cover between its exit from the pre-shrinking section (i.e. upstream) in the machine direction 1. Pressing area 74 and its entry into the pressing area 74 arranged downstream in machine direction 1 (i.e., downstream).
  • the free shrink length is the length over which the fibrous web 81 runs in machine direction 1 between two drying cylinders 72 with drying wires 73. Along the free shrink length, the fibrous web is given the opportunity to shrink.
  • the free shrink length is approximately 17.5 m.
  • FIG. 1 b A representation showing a complete drying section according to the invention, also used as a post-drying section 20, is Fig. 1 b and c.
  • the fibrous web is fed directly from the compression device 21 into the after-drying section 20, which begins with a sequence of three drying cylinders 72 with separate drying wires 73. These three drying cylinders 72 form the contact drying area 70 of the after-drying section 20 according to the invention.
  • Fig. 1 the dryer section shown in Fig. 1 is similar to that shown in Fig. 8.
  • the fibrous web emerging from the compression device 21 has a dry content of approximately 65% and is introduced into a post-drying section 20 designed according to the invention.
  • the cylindrical rollers 79 are heated to a temperature of approximately 110-160°C, so that the fibrous web 81 is also heated, and the moisture escaping from the fibrous web 81 creates a vapor cushion that forms between the fibrous web 81 and the outer surface of the cylindrical rollers 79. This allows for free shrinkage as the fibrous web 81 continues to dry.
  • the resulting kraft paper exhibits a variety of advantageous properties.
  • the kraft paper produced according to the described embodiment can exhibit the exemplary property profile listed in Table 1 above.
  • Fig. 9 shows an enlarged view of a dryer section according to another embodiment in detail.
  • the dryer section according to this embodiment can also be used in the plant shown in Fig. 1 to produce kraft paper.
  • each impact drying section 83 has three impact drying devices 77, each of which in turn comprises a cylindrical roller 79 or a further drying cylinder 80, as well as a drying hood.
  • the calendering station 22 included in the system according to Fig. 1 can be replaced by an embossing station 84.
  • this can be an embossing station 84 as schematically shown in Fig. 10.
  • the embossing station 84 comprises an embossing roller 85 and a counter roller 86, with an embossing gap 87 arranged between the embossing roller 85 and the counter roller 86.
  • the fibrous web emerging from the dryer section is guided through this embossing gap 87.
  • An embossed structure 88 is provided on the surface of the embossed roller 85, which essentially corresponds to the embossed profile to be formed on the fibrous web.
  • the surface of the counter roll 86 is smooth, but covered with an elastic material.
  • the elastic material has a Pusey & Jones hardness of approximately 30.
  • the embossing station 84 includes an adjusting device 96 by which the position of the counter roll 86 can be adjusted, thus adjusting the rolling pressure in the embossing gap 87.
  • the fibrous web emerging from the embossing nip 87 exhibits the final embossed profile. No further active drying step is required, and the fibrous web can be rolled up directly.
  • a cleaning arrangement is also provided, which comprises a cleaning brush 90 and an application device 94.
  • the cleaning brush 90 is designed as a rotating brush with a rotary drive.
  • the width of the cleaning brush 90 is less than the width of the embossing roller 85.
  • a drive is also provided to move the cleaning brush 90 back and forth along the rotational axis 91 of the embossing roller 85.
  • the rotational axis 91 of the embossing roller 85 runs essentially parallel to the rotational axis 92 of the cleaning brush.
  • the application device 94 is designed as a spray device that can spray a water-air mixture as a cleaning agent onto the surface of the embossing roller 85. This improves the cleaning effect of the cleaning brush 90.
  • the embossed structure obtained by means of such an embossing station 84 can, as shown in Figs. 11a and 11b, be formed from pyramid-shaped impressions 89 with a rectangular base, separated from one another by flat sections 95. No impressions 89 are provided in the flat sections 95.
  • the embossing depth 93 of the impressions 89 is approximately 0.3 mm in this exemplary embodiment.
  • the width of an impression 89 here is approximately 0.6 mm and the length approximately 0.9 mm.
  • the indentations 89 are arranged in indentation rows 97, which are formed by a plurality of adjacent indentations 89 extending in the transverse direction 98 of the paper. Compared to the transverse direction 98, the indentation rows 97 are arranged at an angle of approximately 1°.
  • the distance between the impressions 89 of two adjacent rows of impressions 97 is approximately 2.2 mm in this embodiment.
  • Consecutive impressions 89 of two impression rows 97 in the machine direction 99 of the paper are offset.
  • the impressions 89 are therefore not arranged directly above one another in the machine direction 99, but rather are offset at an angle.
  • the offset is approximately 0.6 mm. This results in impression columns 100 that run at an angle to the machine direction 99.
  • the system shown in Figs. 1a to c can comprise system components according to any of the exemplary embodiments described here.
  • a system for producing kraft paper is also disclosed, which has the basic features of the system shown in Figs. 1a to c and is equipped with a wire section as shown in Fig. 2, with an upsetting device as shown in Fig. 3, and with an embossing station as shown in Fig. 12.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Paper (AREA)

Abstract

L'invention se rapporte à un procédé de production de papier kraft, comprenant les étapes suivantes consistant à : former une bande fibreuse s'étendant le long du sens machine (1) par application continue d'une suspension fibreuse sur une section de fil (2) au moyen d'une caisse de tête (3) ; presser la bande fibreuse préalablement partiellement déshydratée dans la section de fil (2) dans une section de pressage (5) ; compacter éventuellement la bande fibreuse formée dans le sens longitudinal de la machine au moyen d'un dispositif de compactage (21), en particulier au moyen d'un dispositif Clupak ; sécher davantage la bande fibreuse dans une section de séchage (6) ; éventuellement calandrer, en particulier gaufrer, la bande fibreuse dans une station de calandrage (22) ; et enrouler la bande de papier formée à partir de la bande fibreuse dans une station d'enroulement (7), la vitesse de production étant supérieure à 600 m/min, et la largeur de la bande fibreuse étant supérieure à 4,5 m, en particulier supérieure à 5,5 m. L'invention se rapporte également à une installation de production de papier kraft.
PCT/AT2025/060030 2024-01-30 2025-01-28 Procédé de production de papier kraft Pending WO2025160610A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AT500702024 2024-01-30
ATA50070/2024 2024-01-30

Publications (1)

Publication Number Publication Date
WO2025160610A1 true WO2025160610A1 (fr) 2025-08-07

Family

ID=94478400

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/AT2025/060030 Pending WO2025160610A1 (fr) 2024-01-30 2025-01-28 Procédé de production de papier kraft

Country Status (1)

Country Link
WO (1) WO2025160610A1 (fr)

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH337723A (de) * 1958-07-09 1959-04-15 Clupak Inc Einrichtung zum Behandeln einer feuchten Papierbahn
DE1133236B (de) * 1958-01-20 1962-07-12 Clupak Inc Verfahren zum Herstellen ungekreppter, dehnbarer Bahnen aus Papier, Textilien od. dgl.
FR2145879A5 (fr) * 1971-07-09 1973-02-23 Neyrpic
US5921000A (en) * 1997-01-27 1999-07-13 Beloit Technologies, Inc. Alternating top and bottom felted dryers connected without open draw
US20040076798A1 (en) * 2001-02-12 2004-04-22 Nils-Ake Larsson Embossed high flexible paper and a method of producing the same
US20080169072A1 (en) * 2007-01-12 2008-07-17 Cascades Canada Inc. Wet Embossed Paperboard and Method and Apparatus for Manufacturing Same
EP3224409B1 (fr) * 2014-11-28 2021-08-18 Voith Patent GmbH Procédé et dispositif de fabrication de papier d'emballage
EP3835482B1 (fr) * 2019-12-12 2022-07-13 Voith Patent GmbH Machine et procédé de fabrication d'une bande de matière fibreuse

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1133236B (de) * 1958-01-20 1962-07-12 Clupak Inc Verfahren zum Herstellen ungekreppter, dehnbarer Bahnen aus Papier, Textilien od. dgl.
CH337723A (de) * 1958-07-09 1959-04-15 Clupak Inc Einrichtung zum Behandeln einer feuchten Papierbahn
FR2145879A5 (fr) * 1971-07-09 1973-02-23 Neyrpic
US5921000A (en) * 1997-01-27 1999-07-13 Beloit Technologies, Inc. Alternating top and bottom felted dryers connected without open draw
US20040076798A1 (en) * 2001-02-12 2004-04-22 Nils-Ake Larsson Embossed high flexible paper and a method of producing the same
US20080169072A1 (en) * 2007-01-12 2008-07-17 Cascades Canada Inc. Wet Embossed Paperboard and Method and Apparatus for Manufacturing Same
EP3224409B1 (fr) * 2014-11-28 2021-08-18 Voith Patent GmbH Procédé et dispositif de fabrication de papier d'emballage
EP3835482B1 (fr) * 2019-12-12 2022-07-13 Voith Patent GmbH Machine et procédé de fabrication d'une bande de matière fibreuse

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
ANDRITZ AG: "Wie l�sst sich Verpackungspapier m�glichst effizient f�r Wachstumsm�rkte produzieren?", 4 August 2018 (2018-08-04), pages 1 - 6, XP093266664, Retrieved from the Internet <URL:https://www.andritz.com/newsroom-de/erfolgsgeschichten/verpackungspapier-effizient-fuer-wachstumsmaerkte-produzieren> [retrieved on 20250403] *
HOLIK H ET AL: "Paper and Board, 6. Manufacturing", 15 January 2012, ULLMANN'S ENCYCLOPEDIA OF INDUSTRIAL CHEMISTRY, PAGE(S) 1 - 57, XP002714492 *

Similar Documents

Publication Publication Date Title
DE4224730C1 (en) Tissue paper mfg. machine preventing moisture return - comprises shoe press for press unit(s) for drying tissue web, for min. press units
DE4102356C1 (fr)
AT406694B (de) Verfahren zur entwässerung endloser faserstoffbahnen sowie siebpartie einer maschine zur herstellung von faserstoffbahnen
AT400857B (de) Maschine zur herstellung einer faserstoffbahn
DE102010029580A1 (de) Maschine zur Herstellung einer Papierbahn insbesondere Sackpapierbahn
DE2420029C3 (de) Preßeinrichtung zum kontinuierlichen Herstellen von Spanplatten, Faserplatten o.dgl
EP0989232A2 (fr) Section de séchage
EP2313552B1 (fr) Procédé d&#39;optimisation du bilan énergétique des unités de formage dans des machines de fabrication de bandes de matières fibreuses, ainsi qu&#39;unité de formage
DE69618896T2 (de) Einsieb-Trockenpartie angepasst zur Kompensation des Recken und Schrumpfens einer Papierbahn
DE3604522A1 (de) Papiermaschinenpressenpartie mit separaten pressenspalten
DE4201107C2 (de) Trockenpartie
WO2025160610A1 (fr) Procédé de production de papier kraft
DE2336518B2 (de) Vorrichtung zum behandeln von webketten
WO2025160606A1 (fr) Dispositif de compression et procédé de production de papier kraft
WO2025160604A1 (fr) Procédé de fonctionnement d&#39;une installation de production de papier kraft
DE733057C (de) Entwaesserungs- oder Abpressmaschine fuer fortlaufend bewegte, nasse Stoffbahnen
AT527984A1 (de) Staucheinrichtung sowie Anlage und Verfahren zur Herstellung von Kraftpapier
WO2025160602A1 (fr) Dispositif de compression, installation et procédé de production de papier kraft
EP2507431A2 (fr) Dispositif pour traiter une bande continue de papier, carton ou autre matière fibreuse
DE9207656U1 (de) Maschine zur Herstellung einer Faserstoffbahn
WO2025160605A1 (fr) Installation et procédé de production de papier kraft, ladite installation comportant un ensemble de dérivation
DE102010036693B4 (de) Verfestigungsverfahren und Verfestigungsvorrichtung zur Verfestigung einer ein Vlies umfassenden Warenbahn
WO2025160607A1 (fr) Section de séchage pour la production de papier kraft
DE4008870A1 (de) Verfahren zur kontinuierlichen behandlung eines leichten, lockeren gewebes oder gewirkes oder eines aehnlichen gutes sowie vorrichtung zur durchfuehrung des verfahrens
WO2025160600A1 (fr) Procédé de fabrication de papier kraft

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 25702945

Country of ref document: EP

Kind code of ref document: A1