JP2009520114A - Paper machine having one or more valve devices - Google Patents

Abstract

  The present invention relates to the use of a piezoelectric nozzle system in a paper machine. Piezoelectric nozzle systems have proved unexpectedly well suited to extreme ambient conditions in paper machines. In particular, very high regulation accuracy and dynamics can be achieved when a controlled or regulated valve device is utilized in a paper machine by utilizing a piezoelectric nozzle system despite the high moisture content. The use of a piezoelectric nozzle system further ensures that the corresponding valve device is designed to be very rugged and very compact, ensuring high availability and stability.

Description

  The present invention relates to a paper machine having one or more valve devices.

  In a paper machine, paper, cardboard and / or paperboard are produced. Valve devices can be used at various points in paper machines.

  German Patent No. 3126460 discloses, for example, a paper machine flow box device, in which a plurality of valve devices formed as a nozzle system are used, with a liquid jet formed from a stock suspension. Out of the valve device.

  German Patent No. 3144066 describes a flow box for a paper machine, which is provided with a single valve device having a plurality of turbulent tubes that pour into a discharge nozzle.

  German Patent No. 2917765 discloses, for example, a nozzle for a floating dryer, which is used in a paper machine to dry a paper web in a non-contact manner.

  The felt cleaning device known from JP-A-2-80689 has a single valve device with a cleaning nozzle. Such felts and corresponding cleaning devices are used, for example, in the press part of paper machines.

  No. 2,917,765 discloses a floating dryer nozzle. A floating dryer can be used in a paper machine to dry a paper web in a non-contact manner. A valve device formed as a nozzle, known from DE 29 17 765 A1, serves to direct the drying and supporting gas stream to the paper web to be dried.

  The paper machine cylinder dryer known from EP 0051654 has one or more valve devices formed as air injection elements.

  German Patent No. 3218306 discloses a cutting and guiding device for an introductory strip separated from the end of a paper web for delivering the paper web, the cutting and guiding device having a valve device, The paper web is exposed to airflows opposite to each other by these valve devices, and the paper web tears as a result of the tensile stress acting on the paper web.

  For example, the valve devices known from the above specifications can be installed in paper machines with high moisture, some very high ambient temperatures, chemical loads, and / or relatively severe ambient conditions such as, for example, paper fiber contamination. It is characterized by. The mechanical and / or electromechanical valve devices currently used in paper machines are relatively prone to failure, which results in paper machine production loss and quality degradation.

  An object of the present invention is to increase productivity and quality during operation of a paper machine.

  This problem is solved by a paper machine having one or more valve devices, at least one valve device having at least one piezoelectric nozzle system.

  The piezoelectric nozzle system, when used in a paper machine, has surprisingly been found to be much more reliable than previously used electromechanical valves. By utilizing a piezoelectric nozzle system in a paper machine, the accuracy and dynamics of the process adjustments that occur in the paper machine can be further increased. A paper machine having at least one valve device formed as a piezoelectric nozzle system works much more reliably and is more robust than known paper machines. The present invention increases the availability and stability of the paper machine.

  Advantageously, the piezoelectric nozzle system can have multiple zones, the zones being controllable to adjust the flow rate of each zone. In particular, the number of possible bands can be increased essentially by utilizing at least one piezoelectric nozzle system. Increases resolution and adjustment quality. The play of the adjusting element of the valve device is reduced.

  It is advantageous if at least one piezoelectric nozzle system can be provided in the region of the flow box for depositing the pulp on the plow net. In this way, the fiber alignment can be adjusted by a specific control pattern when the paper is placed, whereby other paper parameters such as longitudinal rigidity and lateral rigidity can be well controlled.

  Accordingly, it is advantageous if the piezoelectric nozzle system can be configured to affect fiber alignment.

  It is advantageous to provide at least one piezoelectric nozzle system for coating the paper.

  Advantageously, the piezoelectric nozzle system can be configured to deposit an adhesive.

  It is also preferred that the piezoelectric nozzle system be configured to apply a pigment.

  In an advantageous configuration of the invention, at least one piezoelectric nozzle system for humidifying the paper can be provided.

  It is also preferred to have at least one piezoelectric nozzle system for cleaning the plow net.

  It is also advantageous to provide at least one piezoelectric nozzle system for forming or shaping a jet for cutting the paper, for example a water jet or an air jet.

  Other advantages and details of the invention will be described in the form of embodiments on the basis of the drawings.

  FIG. 1 schematically shows a paper machine capable of producing, for example, paper, cardboard or paperboard. The paper machine can have a stock tank 3 that receives feed 2 such as waste paper, chemical pulp and / or mechanical pulp. In some cases, components that are distant from the paper are sorted by the sorter 4, for example.

  The flow box 5 of the paper machine transfers the fiber-water-suspension 7 formed from the raw material 2 with the addition of water and optionally with fillers and / or auxiliary materials to the paper machine wire part 6. Distribute uniformly across the width of at least one plow 10. In the illustrated embodiment, the plow net 10 is formed as a very fine endless plow net, which constantly moves forward and is preferably swung in the lateral direction. The pulp flowing out of the flow box 5, ie the fiber-water-suspension 7 can have up to 99% water. In the wire part 6, the fibers are intertwined into a unified paper web 1. Excess water flows down through the plow net 10. The water flowing down in the wire part 6 is called white water 9. The water content of the paper web 1 at the end of the wire part 6 can typically be about 80%. In that case, the paper web 1 is already strong enough to be removed from the plow 10 and guided into the subsequent press part 11 using a felt band.

  In the press part 11, the paper web 1 is further dewatered. The water content of the paper web 1 can be reduced to 50%, for example. The water that flows down in the press part 11 is also referred to as press water 12. The white water 9 and the press water 12 are supplied as circulating water 16 directly to the stock preparation section, that is, the stock tank 3, the sorter 4 and / or the flow box 5, or via the so-called stock collection device 14. it can. Waste water 15 is advantageously supplied to the treatment facility.

  In the press part 11, the paper web 1 is preferably passed between steel, granite and / or hard rubber rolls by means of an absorbent endless felt cloth and thereby dewatered. The pressing process compresses the paper texture, increases rigidity, and surface quality is critically affected.

  In general, the dryer part 13 following the press part 11 is often the longest part of the paper machine. Water is vaporized from the paper web 1 in the dryer part 13. In the dryer part 13, the paper web should pass through a plurality of steam-heated drying cylinders. In the dryer part 13, the base paper can be dried uniformly and generally has a residual moisture of several percent at the end of the dryer part 13. The generated water vapor is preferably sucked from a sealed dry hood (not shown in detail) and sent to the heat recovery facility. It is no exception that the dryer part 13 has up to 100 or more steam-heated drying cylinders. The paper web 1 is generally wound on a reel 8 at the end of the paper machine. The paper machine can have a calendar (not shown in detail in the drawings), and this calendar is generally provided downstream of the dryer part 13 and upstream of the reel 8. The calendar is generally composed of a plurality of upper and lower rolls not shown in detail in the drawings, and the rolls give the paper web a smooth surface and a uniform plate thickness.

  As mentioned above, a paper machine is a plurality of assemblies connected in series. One paper machine has at least two of the following assemblies: a flow box 5, a wire part 6, a press part 11, a dryer part 13, a calendar, and a winder with a reel 8.

  In an advantageous configuration of the invention, a valve device with a piezoelectric nozzle system can be used at various locations in different assemblies of the paper machine.

  Within the flow box 5 the fiber-water-suspension 7 or pulp flows out from a valve device which is formed as a nozzle. This valve device can have one or more piezoelectric nozzles not shown in detail. Advantageously, a plurality of piezoelectric nozzles can form a zone that can be arranged, for example, across the paper web 1 and / or perpendicular thereto. The valve device of the flow box 5 is advantageously arranged in a so-called headbox which substantially coincides with the upper part of the flow box 5 in the drawing, in particular the part formed in a “nose” shape.

  The piezoelectric nozzle system can also be used to clean and keep the screen 10 of the wire part 6 and / or the press felt of the press part 11 and / or the drying screen of the dryer part 13. Piezoelectric nozzle systems are used, for example, to clean the net 10 particularly effectively. For example, a plurality of piezoelectric nozzles can be placed across the paper web 1 to clean the plow 10. In this case, air is blown continuously over the width of the plow net traveling, which advantageously removes water and dirt particles in the plow net. The piezoelectric nozzle system can also be used to clean rolls, for example suction rolls in wire part 6 and / or press part 11.

  Although the paper web 1 is dried as a whole in the paper machine, it is desirable to humidify the paper web 1 at various points in order to improve the paper quality. In particular, the paper web 1 is often humidified in a so-called re-drying group not shown in detail in the drawing. In order to humidify the paper web 1, the piezoelectric nozzle system is used for lateral moisture distribution, curl reduction and / or rehumidification depending on the mounting location. The use of a piezoelectric nozzle system makes it possible in particular to achieve an optimum spray angle and fine water droplet formation in combination with a suitable control mechanism, thereby achieving a very uniform water absorption throughout the paper web 1. it can. A high paper quality is thus achieved, which improves, for example, the winding of the paper web 1 and reduces cracks.

  The piezoelectric nozzle system can also be used to cut the paper web 1. The paper web 1 is cut with water and / or air flowing out of the piezoelectric nozzle. A piezoelectric nozzle system can form a finely directed water jet that cuts the paper web cleanly, rigorously and without dust at optimum water pressure. Such a paper web cutting system which relies on one or more piezoelectric nozzle systems is particularly suitable for cutting the edges of the paper web 1.

  High quality qualitative color and / or adhesive coating of the paper web 1 can also be performed using one or more piezoelectric nozzle systems. For this purpose, a coating device or an adhesive press is preferably provided in the paper machine. Adhesive application and / or color coating of the paper web is preferably performed after or during the drying process. Using a piezoelectric nozzle system, the paper web 1 can be coated in a particularly uniform and precisely controllable layer thickness.

  Piezoelectric nozzle systems in paper machines are generally designed for much higher flow rates than, for example, piezoelectric nozzle systems utilized in the vehicle industry. By utilizing the piezoelectric nozzle system in a paper machine, the valve device of the paper machine can be made much more compact than previously possible.

  The important ideas for the present invention are summarized below.

  The present invention relates to the use of a piezoelectric nozzle system in a paper machine. Piezoelectric nozzle systems have proved unexpectedly well suited to extreme ambient conditions in paper machines. In particular, very high regulation accuracy and dynamics can be achieved when a controlled or regulated valve device is utilized in a paper machine by utilizing a piezoelectric nozzle system despite the high moisture content. The use of a piezoelectric nozzle system further ensures that the corresponding valve device is designed to be very rugged and very compact, ensuring high availability and stability.

1 is a schematic diagram of a paper machine according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Paper web 2 Raw material 3 Paper tank 4 Sorter 5 Flow box 6 Wire part 7 Fiber-water-suspension 10 Plow net

Claims (10)

  A paper machine having one or more valve devices, wherein at least one valve device has at least one piezoelectric nozzle system.   The paper machine of claim 1, wherein the piezoelectric nozzle system has a plurality of zones, the zones being controllable to adjust the flow rate of each zone.   3. A paper machine according to claim 1, wherein at least one piezoelectric nozzle system for depositing pulp on the plow net is provided in the region of the flow box.   4. A paper machine according to claim 3, wherein the piezoelectric nozzle system is configured to influence fiber alignment.   A paper machine according to any one of the preceding claims, wherein at least one piezoelectric nozzle system is provided for coating the paper.   6. The paper machine according to claim 5, wherein the piezoelectric nozzle system is formed to deposit an adhesive.   7. A paper machine according to claim 5 or 6, wherein the piezoelectric nozzle system is formed to deposit a pigment.   A paper machine according to any one of the preceding claims, wherein at least one piezoelectric nozzle system is provided for humidifying the paper.   A paper machine according to any one of the preceding claims, wherein a cleaning device for the plow net (10) is provided, the cleaning device having at least one piezoelectric nozzle system.   A papermaking machine according to any one of the preceding claims, wherein a paper cutting device is provided, the cutting device having at least one piezoelectric nozzle system, and a jet for cutting the paper is formed with this piezoelectric nozzle system. Machine.

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