DE102018113495A1 - Suction device and method of aspiration for a papermaking machine - Google Patents

Abstract

There is disclosed a suction device in a vacuum zone of a paper machine, the paper machine having a screen (50) and a reciprocally movable suspension port (60) for applying a paper suspension to the screen (50). The apparatus comprises: a port (110) for a pump; an opening portion (120) having at least one opening connected to the at least one port (110) for the pump to exhaust by means of the pump in the vacuum zone; and control means (130) for controlling the opening area (120) to evacuate at variable positions of the screen (50) in response to a current position of the suspension port (60).

Description

The present invention relates to a suction apparatus and method for vacuuming in a vacuum zone of a papermaking machine, and more particularly to traversing suction during manufacture of paper with highly oriented fibers.

BACKGROUND

The strength properties of paper can be affected by orientation of the fibers in the paper. In order to be able to adjust the fiber orientation during sheet formation, so-called traversing nozzles are used, which apply a highly diluted fiber suspension to a rotating screen in a reciprocal motion. To dewater the suspension, there is a vacuum zone behind the screen, where the applied suspension is specifically dried by aspirating air. The vacuum pump used generates a negative pressure, for example by displacing air. The applied vacuum sucks the liquid through the screen into the vacuum zone while the fibers are retained by the screen. Ideally, the fibers are placed oriented on the screen and fixed by direct suction of the liquid in position.

A known papermaking machine utilizes a screen drum having a fixed circumference on which tangentially the fiber suspension is applied while the screen drum is rotating. The inner area of the sieve drum is sucked off by a vacuum system and thus leads to a drying of the paper wound on the drum. A disadvantage of this approach is that depending on the used drum, the maximum length of the paper is limited (by the drum circumference).

5 shows an example of another known plant for papermaking. The device comprises a traversing nozzle 60 (For example, a glass capillary) through which a fiber suspension on a rotating sieve 50 is applied and a nonwoven fabric 90 arises, being in a vacuum zone 70 a vacuum pump draws in air so as to extract moisture from the suspension. On the left side of the 5 is a cross-sectional view of the rotating screen 50 shown, which is continuously moved over two rollers. The vacuum zone 70 is behind the rotating sieve 50 formed while the nozzle 60 the suspension jet on a front side on the rotating sieve 50 applying. The traversing nozzle 60 moves horizontally in the drawing plane and thereby carries the fiber suspension on the rotating sieve 50 on.

The vacuum zone 70 includes several suction slots, is sucked through the air. The suction slots are connected via smaller hoses to a main line leading to the vacuum pump (not shown). The width of the slots can be chosen arbitrarily in principle. Here, however, the suction power of the vacuum pump is to be considered, since the applied negative pressure with too wide slots is not sufficient to dewater the fiber fleece. With wider slots, a correspondingly stronger vacuum pump would have to be used. To make wide paper, the slots and thus the vacuum zone should extend to the full width of the screen - at least as wide as the material is applied. In order to increase the width of the paper to be produced, the suction slots are to be widened (eg to 180 mm) in order to use the full screen area.

• - Der dünne Suspensionsstrahl befeuchtet nur einen kleinen Teil des Siebes und des Absaugschlitzes. Auf beiden Seiten des Strahls wird daher Falschluft angesaugt, wodurch sich die Saugleistung verringert und das Faservlies weniger entwässert wird.
• - Daher reicht die Saugleistung der vielen Schlitze häufig nicht aus, sodass Wasser am Sieb herabläuft, an dem Umlenkpunkt zum Aufschwimmen der Fasern führt und damit die gewünschte Orientierung der Fasern zerstört wird (z.B. wenn die Saugschlitze zu breit sind). Dies verhindert die Produktion breiter Faservliese.

• - In den Bereichen, in denen die Düse gerade keine Suspension aufbringt, aber bereits Fasern abgelegt wurden, trocknen die Fasern aus. Hierdurch kann zum einen Falschluft gezogen werden und zum anderen wird das Papier in die Siebstruktur gesaugt, was sich auf die Papiereigenschaften auswirkt und das Ablösen des Papiers vom Sieb erschwert.
• - Eine mögliche Abhilfe mittels eines Schiebers zum Abdecken der Absaugschlitze führt nur zu einer leichten Verbesserung der Ergebnisse, bei gleichzeitig extrem erhöhten manuellen Aufwand bei der Anlagensteuerung.

However, this results in at least the following problems:

• - The thin suspension jet humidifies only a small part of the sieve and the suction slot. False air is therefore drawn in on both sides of the jet, whereby the suction power is reduced and the fiber fleece is less dehydrated.
• - Therefore, the suction power of the many slots is often not sufficient, so that water runs down the wire, leading to the deflection point to float the fibers and thus the desired orientation of the fibers is destroyed (eg if the suction slots are too wide). This prevents the production of wide fiber webs.

• - In the areas where the nozzle is currently not applying any suspension but fibers have already been deposited, the fibers dry out. In this way, on the one hand false air can be pulled and on the other hand, the paper is sucked into the screen structure, which has an effect on the paper properties and makes the detachment of the paper from the screen more difficult.
• - A possible remedy by means of a slide to cover the suction slots leads only to a slight improvement in the results, at the same time extremely increased manual effort in the system control.

Therefore, the paper produced by the known equipment has a poor surface structure and formation, and there is a need for improvements for a papermaking machine (papermaking machine) in order to be able to produce the full width paper on the one hand and overcoming at least some of the above drawbacks.

BRIEF DESCRIPTION OF THE INVENTION

This object is achieved by a device according to claim 1 and a method according to claim 11. The dependent claims relate to advantageous developments of the device according to claim 1.

The present invention relates to a suction device in a vacuum zone of a papermaking machine. The papermaking machine comprises a screen and a reciprocally movable suspension port (traversing application port) for applying a paper suspension to the screen. The apparatus comprises: a port for a pump for generating a negative pressure (e.g., a vacuum pump); an opening portion having at least one opening connected to the at least one port for the pump to suck by means of the pump in the vacuum zone; and control means for controlling the opening area to perform suction at changeable positions (perpendicular) to the direction of deflection of the screen depending on a current position of the suspension opening. It should be sucked in particular moisture or water, so that the pump should be designed to be able to suck in addition to air and water or a water / air mixture. This will remove liquid / moisture from the paper.

In the context of the present invention, a position is to be understood as meaning in particular the position perpendicular to a relative movement between the suspension opening and the sieve (ie in FIG 5 the position in the horizontal direction). In addition, the term suspension port should be interpreted broadly and include any opening capable of orienting fibers in the suspension or being an opening of a hose in which fibers are aligned. This can be, for example, a narrowing mouth or nozzle. The desired fiber orientation can also be achieved by a targeted change in the flow velocity profile.

Optionally, the opening portion includes one or more slots that are movable relative to the wire. The control device can accordingly be designed to adapt the position of the one or more movable slots to the position of the suspension opening. For example, the slots can be moved by means of a carriage or carriage on a linear guide perpendicular to the relative movement between the suspension opening and the sieve traversing parallel to the surface of the screen. The movement of the suspension opening and / or the opening area can take place, for example, via one or more stepping motors. In this way, a suction of false air can be significantly reduced, since only there air or an air / water mixture is sucked where a drying is carried out.

Optionally, the opening portion includes a plurality of openings, and the control means is configured to open or close the openings individually or in groups based on a position of the movable suspension opening. It can thereby be achieved that at least one opening is opened at the position of the suspension opening and the openings are closed at other positions where the movable suspension opening is not located or there is no suspension application. Through these switchable openings suction of false air can be lowered.

Optionally, the control device is further configured to synchronize the variable position of the suction with the position of the movable suspension opening. For example, the opening area can be moved with the carriage on the exemplary linear guide together with the suspension opening or the respectively open opening can be performed parallel to the movement of the suspension opening, so that is sucked only in the area where a suspension order is done.

Optionally, the screen in the papermaking machine is a rotating screen or a fixed screen or a rotating screen or a mutually movable screen. The control device can then move the variable position relative to the screen in the same way as the suspension opening.

Optionally, the at least one opening is an opening controllable by the control unit to control a (sub) pressure value at the at least one opening (e.g., using a ball valve).

The present invention also relates to a paper machine comprising: a device as described above; a sieve; and at least one traversing suspension port (which is movable perpendicular to relative movement between the screen and the suspension port) for jet-spreading the paper suspension onto the screen and producing a paper sheet of increasing width.

The width of a manufactured nonwoven fabric is determined, for example, by the traverse width (lateral displacement of the suspension opening), which becomes the thickness of the nonwoven fabric for example, about the number of traversing operations (eg number of layers).

Optionally, the papermaking machine further comprises a holder for the screen, wherein the holder holds the screen immovable or rotating or revolving or mutually movable. The opening area and the suspension opening may be arranged immovably to each other or be controlled accordingly, so that they move in a common mode. This can be achieved by a common mount or a synchronized mount. For this purpose, arms may be provided which respectively hold the opening area and the suspension opening and are controlled accordingly (e.g., by the control unit) so that they do not change their relative position while moving relative to the screen.

Optionally, the at least one suspension port forms an array for parallel application of a plurality of paper suspension steels to the screen (e.g., sheet-like).

• - Ansaugen in dem Öffnungsbereich über zumindest eine Öffnung; und
• - Ändern des Öffnungsbereiches in Abhängigkeit einer gegenwärtigen Lage der Suspensionsöffnung, um an einer anderen Position abzusaugen.

The present invention also relates to a method of sucking (eg moisture and / or air) in a vacuum zone of a papermaking machine, the papermaking machine comprising a screen, a reciprocally movable suspension port for applying a paper suspension to the screen and an opening section for aspiration. The method comprises the steps:

• - sucking in the opening area via at least one opening; and
• - Changing the opening area in response to a current position of the suspension opening to aspirate at another position.

Embodiments solve at least some of the above-mentioned problems thus by a vacuum zone, which moves parallel to the application opening. As a result, a uniform suction regardless of the width of the produced paper can be ensured. By using a screen belt and a corresponding web guide paper of any length can be produced. In contrast, in conventional sieve drums with structurally defined scope, the achievable maximum lengths can not be changed. Another advantage of embodiments is the modular design of the system which is arbitrarily expandable (e.g., multiple nozzles and vacuum zones).

In the known systems glass capillaries are used, which break easily. Exemplary embodiments of the invention use, for example, plastic attachments of pipettes. On the one hand, these do not break off, on the other hand they have a tapering cross-section, which leads to the acceleration of the jet. This has the effect of making the jet narrow so that the fibers orientate in the direction of flow. Therefore, in the context of the present invention, this also means a nozzle or a suspension opening. The size of the suction slot can be fixed, with the position of the suction slots is controlled.

list of figures

• 1 zeigt eine Vorrichtung zum Ansaugen von Luft in einer Vakuumzone einer Papiermaschine gemäß einem Ausführungsbeispiel der vorliegenden Erfindung.
• 2 zeigt ein Ausführungsbeispiel mit einem rotierenden Sieb.
• 3 zeigt ein Ausführungsbeispiel mit einem festen Sieb.
• 4A,4B zeigen verschiedene Ausführungsformen für den Öffnungsbereich.
• 5 zeigt eine konventionelle Anlage zur Papierherstellung.

The embodiments of the present invention will be better understood from the following detailed description and the accompanying drawings of the different embodiments, which should not, however, be construed as limiting the disclosure to the specific embodiments, but for explanation and understanding only.

• 1 shows an apparatus for drawing air in a vacuum zone of a paper machine according to an embodiment of the present invention.
• 2 shows an embodiment with a rotating screen.
• 3 shows an embodiment with a solid sieve.
• 4A . 4B show various embodiments for the opening area.
• 5 shows a conventional plant for papermaking.

DETAILED DESCRIPTION

1 shows an embodiment of the present invention for the device for sucking or sucking air, which is suitable for a vacuum zone of a paper machine (ie, a machine for the production of paper). The paper machine comprises an example circulating sieve 50 and a suspension opening 60 , which are mutually perpendicular to the direction of rotation U of the rotating sieve 50 in a traversing direction M is movable. The suspension opening 60 includes a tapered region 62 containing the paper suspension on the rotating sieve 50 applying. The job is done in or near a vacuum zone that has an opening area 120 includes. The opening area 120 has at least one opening 121 . 122 . .. , on that with a connection 110 is connected for a vacuum pump to suck in air by means of a pump in the vacuum zone.

In addition, the opening area 120 with a control device 130 connected to the opening area 120 depending on the current position of the suspension opening 60 to change. For example, the opening area 120 on a linear guide 170 be attached to perpendicular to the direction of rotation U of the sieve 50 to be horizontally movable. The control device 130 can be the traversing movement M the suspension opening 60 with the mutual movement of the opening area 120 synchronize, so that the opening area 120 always located at the horizontal position where the suspension opening 60 the paper suspension on the rotating sieve 50 applying. The control unit 130 can also directly to the mutually movable suspension opening 60 to control the movement of the suspension opening 60 to control.

The orientation of the fibers is determined by the shape of the suspension opening 60 reached. However, the orientation does not necessarily have to be through the suspension opening 60 arise. In general, any stretch flow can be used for fiber orientation. This flow becomes narrower, for example, as a result of an elongation of the jet (for example in a nozzle or as a result of the acceleration in free fall), whereby the fibers are oriented in the flow direction.

The funnel-shaped area 62 aligns the fibers in the paper suspension along the flow direction. Advantageously, the geometry is chosen so that a laminar flow profile (with a parabolic flow profile) within the suspension opening 60 formed. With increasing length of the thinned section 62 the orientation of the fibers is further improved, ie the proportion of non-oriented fibers decreases with the length. The fibers have, for example, a diameter between 20 and 50 μm. For example, this alignment with an inner diameter of the suspension opening 60 or the tapered area 62 of about 0.5 mm - 2 mm, with the tapered region 62 is formed to a length that achieves the desired orientation (eg to at least 5 mm). It is understood that the values mentioned can be chosen freely depending on the fibers in the suspension and are only examples.

2 shows a further embodiment in which the sieve 50 a rotation relative to the paper machine R can perform. In this embodiment, the suspension opening 60 for example, together with the opening area 120 through a common bracket 65 can be held, which can move radially (see double arrow), so that a round or annular paper sheet can be made. The holder 65 can with the connection 110 be connected for the vacuum pump.

It is of course also possible that the suspension opening 60 and the opening area 120 be held by their own brackets (eg by arms), in which case the movements are advantageously synchronized relative to the screen, so that the water / moisture can be pumped out immediately after application.

3 shows a further embodiment in which the sieve 50 is fixed relative to the paper machine. In this embodiment, the suspension opening 60 for example, with an arm holder 116 being held. In the same way, the opening area 120 with another arm holder 115 being held. The arm mounts 115 . 116 can in turn be controlled so that the opening area 120 relative to the suspension opening 60 not or hardly moved - at least not during the application of the suspension. It is understood that small relative movements are possible, for example, to suck a residual moisture from those areas where the suspension has already been applied.

In further embodiments, are also for the rotating screen 50 from the 2 Arm mounts formed as in the 3 are shown. In addition, the sieve 50 in the 3 also move (eg reciprocally reciprocate or move back and forth) while the suspension opening 60 and / or the opening area 120 immovable. These kinematic reversals should also be included in the present invention. The same applies to the embodiment of the 2 , Also the suspension opening 60 and / or the opening area 120 can turn at least partially.

Therefore, the present invention is not intended to be a circumferential sieve 50 be limited. Even with a fixed sieve 50 can the nozzles 60 (Suspension openings) z. B. be moved by a robot arm and thus allow the sheet formation according to embodiments. The suction device can then also with the nozzles 60 be moved.

4A and 4B show various embodiments for the opening area 120 ,

In the embodiment of the 4A the opening area comprises movable elements 121 . 122 . 123 with corresponding openings perpendicular to the exemplary direction of rotation of the rotating screen 50 are movable. The opening area 120 is an example of a rotating sieve 50 explained. It is understood, however, that the described opening areas 120 also for the sieves 50 from the 2 and 3 are applicable. The moving elements 121 . 122 . .. , are exemplified as slots, wherein in a central region suction ducts 125 are intended for the moisture / water / air, which are towards the vacuum connection 110 lead (not shown).

In the embodiment shown, by way of example, three openings 121 . 122 . 123 provided, the corresponding control by the control device 130 can move in a horizontal direction. The control unit 130 For example, make sure that the slots or openings 121 . 122 ... are in each case at the point where the suspension opening 60 the suspension on the rotating sieve 50 applying. The three slots 121 . 122 , ... can be moved at the same time or independently of each other in order to create different (sub) pressure profiles below the rotating screen 50 to reach.

In further embodiments, more or fewer slots may also be used 121 , ... be provided. It is also possible that the openings in the individual slots 121 , ... can be chosen differently (eg in terms of height, width, shape, etc.). In particular, it is possible, the opening width of the suspension opening 60 adjust, so that as little false air is pulled.

The 4B shows embodiments for switchable openings or zones 126 . 127 . 128 , ..., which can have different shapes, but can themselves be immobile. The switchable zones 126 . 127 , ... may, for example, have a rectangular shape, which are arranged in several rows one above the other or adjacent to each other (see the illustrations above left and top right in the 4B) , Other options are that the switchable zones 121 . 122 , ... form arrow-shaped areas (upper row in the middle) or a honeycomb-shaped or diamond-shaped pattern (see bottom row in 4B) ,

Between the switchable zones 126 . 127 . 128 , ... gaps may or may not be provided. So can the zuschaltförmigen zones 126 . 127 . 128 also directly adjacent to each other. In particular, webs between the zones 126 . 127 , ..., which promote drainage of water.

Each switchable zone again comprises a suction channel in a central area 125 for the water that goes to the vacuum port 110 leads (not shown). Inside the suction channels 125 For example, valves may be provided which control the amount of suction on control signals of the control device 130 regulate. The control can be binary (switching between open and closed) or stepwise or analog. The connection to the vacuum pump can therefore close or open continuously or in several steps. This makes it possible for a vacuum profile to be flexible below the rotating screen 50 can be produced (eg, depending on a degree of moisture). In those places, by the suspension opening 60 For example, as much moisture or air as possible can be sucked in, while less or no air is sucked in areas farther from the suspension opening position.

In both embodiments (from the 4A and 4B) can the (under) pressure on each suction channel 125 be controlled flexibly, for example via a ball valve. The controller can be controlled by the control unit 130 respectively.

In the embodiments of the 1 and 4A can the slots 121 . .. , any width (eg between 20 mm and 100 mm or about 45 mm) and any height (eg between 1 mm and 10 mm or about 5 mm) have. The slots 121 . .. , For example, they may be formed in a PTFE sheet which is mounted on a carriage and moved along a linear guide. Parallel and analogous to the movement of the suspension opening 60 can thus the opening area 120 (Vacuum zone) are moved via a threaded rod to the right or left, for example, a stepper motor can be used as a drive. The traversal of the suspension opening 60 can be tracked continuously in this way, whereby a synchronous movement of the two components (suspension opening 60 and opening area 120 ).

In addition, it is possible according to further embodiments, that several suspension openings 60 form an array next to each other so that the paper suspension can be applied in parallel. For this it is possible that each of these suspension openings has its own vacuum zone (opening area 120 ) or that a common vacuum zone is provided for the array.

By the uniform suction on the sieve 50 and the associated uniform moisture distribution over the wire width, the paper can be easily removed from the screen after sheet formation. For example, after completion, the paper may turn off in an area near the bottom circulation roll 1 be removed. In principle, in this way paper can be produced in any length and width (depending on the width of the rotating screen). In particular, paper dimensions of 420 mm * 1560 mm pose no problem.

• - Es gibt keinen Übergang zwischen verschiedenen Vakuumschlitzen, an denen sich die Saugleistung ändert.
• - Das Wasser kann entlang von Stegen zwischen den einzelnen Zonen ablaufen oder das Wasser wird durch den Unterdruck in Saugschlitze gesogen und anschließend vom Luftstrom zur Vakuumpumpe mitgerissen.
• - Die Absaugung findet gezielt in der Zone des Suspensionsauftrages statt.
• - Die Antriebskomponenten sind vorhanden und analog zur Suspensionsöffnung 60 einsetzbar.
• - Die Anschaffungskosten sind gering.
• - Der Steueraufwand ist gering.

Exemplary embodiments have the following advantages in particular:

• - There is no transition between different vacuum slots where the suction power changes.
• - The water can run along webs between the individual zones or the water is sucked by the negative pressure in suction slots and then entrained by the air flow to the vacuum pump.
• - The suction takes place specifically in the zone of the suspension order.
• - The drive components are present and analogous to the suspension opening 60 used.
• - The initial costs are low.
• - The tax expense is low.

In addition, the system can be expanded modularly if required. For example, additional suction devices may be provided. It is also possible to provide a second zone with headbox and suction.

• - lastpfadgerecht gestaltete Bauteile für Bauanwendungen,
• - Substitution von Glasfasern in Faserverbundwerkstoffen,
• - Steuerung des Flüssigkeitstransports in Papier,
• - Erzeugung definierter Porenstrukturen für Filter.

The papers made with the embodiments of the present invention can be used for various applications. Among these are among others:

• - Lastpathgerecht designed components for construction applications,
• Substitution of glass fibers in fiber composites,
• - control of liquid transport in paper,
• - Generation of defined pore structures for filters.

The features of the invention disclosed in the description, the claims and the figures may be essential for the realization of the invention either individually or in any combination.

LIST OF REFERENCE NUMBERS

50

circulating sieve

60

movable suspension opening

62

funnel-shaped suspension opening area

65

common support for the suspension opening and the opening area

70

vacuum zone

90

non-woven fabric

110

Connection for vacuum pump

115, 116

Arm holders for the suspension opening and the opening area

120

at least one opening area

121, 122, ...

movable slots

125

suction

126, 127, ...

switchable zones

130

control device

160

Control for suspension opening

170

linear guide

U

direction of rotation

M

mutual movement of the suspension opening

R

Rotational movement of the sieve

Claims (11)

A suction device in a vacuum zone of a papermaking machine, the papermaking machine having a screen (50) and a reciprocally movable suspension port (60) for applying a paper suspension to the screen (50), comprising: a connection (110) for a pump for generating a negative pressure; an opening portion (120) having at least one orifice (121, ..., 126, ...) connected to the at least one port (110) for the pump for exhausting by means of the pump in the vacuum zone; and a control device (130) for controlling the opening area (120) in order to carry out the suction at changeable positions as a function of a current position of the suspension opening (60). Device after Claim 1 wherein the opening portion (120) has one or more slots (121, 122) movable relative to the screen (50), and wherein the control means (130) is adapted to adjust the position of the one or more movable slots (121 , 122) to the position of the suspension opening (60). Device after Claim 1 or Claim 2 wherein the opening portion (120) comprises a plurality of openings (126, 127, ...) and the control means (130) is adapted to form the openings (126, 127, ...) individually or in groups based on a position of the movable suspension opening (60) to open or close. Apparatus according to any one of the preceding claims, wherein the control means (130) is further adapted to synchronize the changeable position from which air is drawn with the position of the movable suspension port (60). Device after Claim 4 wherein the screen (50) is a rotating or a fixed or a rotating screen and the control means (130) is adapted to move the changeable position relative to the screen (50) in the same manner as the suspension port (60). Apparatus according to any one of the preceding claims, wherein the at least one aperture (121, ..., 126, ...) is an aperture controllable by the control unit (130) to control a pressure value at the at least one aperture. Paper making machine with: a device according to any one of the preceding claims; a sieve (50); and at least one traversing suspension opening (60) to jet-coat the paper suspension onto the screen (50) and to produce a paper sheet of increasing width. Papermaking machine after Claim 7 further comprising a support for the screen (50), the support holding the screen (50) immovable or rotating or revolving or reciprocally movable. Papermaking machine after Claim 7 or Claim 8 , wherein the opening area (120) and the suspension opening (110) are arranged immovably to each other or is driven accordingly. Papermaking machine according to one of Claims 7 to 9 wherein the at least one suspension port (60) forms an array to spray a plurality of paper suspension steels in parallel onto the screen (50). A method of aspiration in a vacuum zone of a papermaking machine, the papermaking machine comprising a screen (50), a reciprocally movable suspension port (60) for applying a paper suspension to the screen (50) and an opening section (120) for exhausting air, with the following steps : Exhausting air in the opening area (120) via at least one opening (121, ..., 126, ...); and Changing the port area (120) in response to a current location of the suspension port (60) to exhaust at another position of the screen (50).

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