EP1891267B1 - Pressing device for compressing paper and/or for extracting carrier liquid from paper and method therefor - Google Patents

Pressing device for compressing paper and/or for extracting carrier liquid from paper and method therefor Download PDF

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Publication number
EP1891267B1
EP1891267B1 EP06755311.5A EP06755311A EP1891267B1 EP 1891267 B1 EP1891267 B1 EP 1891267B1 EP 06755311 A EP06755311 A EP 06755311A EP 1891267 B1 EP1891267 B1 EP 1891267B1
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EP
European Patent Office
Prior art keywords
paper
electrode
plasma
pressing device
produced
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EP06755311.5A
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German (de)
French (fr)
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EP1891267A1 (en
Inventor
Helmut Figalist
Werner Hartmann
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Siemens AG
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Siemens AG
Siemens Corp
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    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F3/00—Press section of machines for making continuous webs of paper
    • D21F3/02—Wet presses
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F3/00—Press section of machines for making continuous webs of paper
    • 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
    • D21H25/04—Physical treatment, e.g. heating, irradiating

Definitions

  • the invention relates to a press device for compacting paper and / or for removing carrier liquid from wet paper, cardboard or cardboard in the manufacture of paper, cardboard or cardboard, wherein the press device is arranged downstream of a screening device and arranged in front of a drying plant.
  • the invention relates to a method for operating the press apparatus according to the invention in the compression of paper and / or removal of carrier liquid from wet paper, cardboard or paperboard in the manufacture of paper, paperboard or cardboard, wherein the press device downstream of a screening device and before a Drying system is arranged.
  • a paper manufacturing plant or in parts of a papermaking plant leaves a, usually still wet paper, cardboard or cardboard a screening area of the papermaking plant and from there into a press area of the papermaking plant. In the press area, the paper, cardboard or cardboard is drained.
  • the term paper or process material is used below to represent paper, cardboard or paperboard.
  • Paper fibers preferably consist of many cellulose chains with many OH groups.
  • the strength of the paper is created by intervening water molecules, which connect the fibers via hydrogen bonds.
  • the number of hydrogen bonds can be increased by compression or slight stretching.
  • the invention has for its object to provide an apparatus and a method to increase the processing speed in papermaking.
  • the device-related object is achieved according to the invention in that at least one first electrode, which is connected to a high-voltage pulse generator, is arranged in or under a pressing region of the press device, in / on the wet paper, cardboard or cardboard or in its immediate vicinity a plasma can be generated.
  • the molecular structure of the paper surface or of the fibers is changed.
  • Treatment with plasma increases the strength of the "sheet" even before the first drying stage.
  • the plasma is generated at a distance of less than 20 cm, preferably less than 10 cm, preferably less than 5 cm from the still wet paper in the press apparatus.
  • a transport roller is prepared as a first electrode.
  • At least one second electrode for plasma generation is present. Between the two electrodes, the plasma is generated, preferably as a corona discharge or a gas discharge. Due to this type of arrangement, the paper is guided between the two electrodes and can thus be treated specifically with plasma.
  • At least one electrode is designed as a plate.
  • the targeted application of plasma to the paper is increased by one more time.
  • a further increase in strength is achieved by a means for introducing gas, in particular air or oxygen, preferably pure oxygen or oxygen with, for example, noble gas as the carrier gas, between or in the immediate vicinity of the electrodes.
  • gas in particular air or oxygen, preferably pure oxygen or oxygen with, for example, noble gas as the carrier gas
  • the paper to be compacted is brought into contact with preferably non-thermal, large-area plasma under atmospheric pressure, the plasma is produced in the immediate vicinity of the paper or in the paper or in its immediate vicinity a gas discharge, in particular a corona discharge, is generated under atmospheric pressure.
  • high-voltage pulses having a duration of less than 10 ⁇ s are generated between electrodes to produce the plasma or the gas discharge.
  • the use of high voltage pulses, which have a duration of less than 10 microseconds, has been found to be particularly advantageous, as will be described later.
  • Radicals may, inter alia, also trigger bleaching chemical reactions, in particular free oxygen O, in particular also a hydroxyl radical OH, in particular ozone O 3 , as well as free functional groups such as OH groups, COOH groups.
  • these functional groups are instrumental in increasing, in particular, the bond strength of the fibers to one another, thereby increasing the tear strength of the paper and thus further increasing the processing speed.
  • a series of different oxidizing and functionalizing radicals are generated in a gaseous phase and used to treat the paper with radicals in the incompletely dried sheet, in the press apparatus or immediately thereafter.
  • this treatment should be used at a content of carrier liquid of 2% to more than 30%.
  • this type of treatment also bleaches the colored substances lying on the surface, for example the adhering lignin or dye residues are oxidatively decolorized.
  • Radicals are generated in gas discharges by the fact that high-energy electrons collide with molecules and thereby dissociate or excite them and thus lead to the formation of radicals.
  • radicals are released immediately, while in the excitation by subsequent radiant transitions UV light is generated, which in turn reacts with and preferably dissociates air and water molecules.
  • eV electron volts
  • UV light is generated, which in turn reacts with and preferably dissociates air and water molecules.
  • high electric fields are required. These high field strengths occur in particular at the head of so-called streamers.
  • Streamer are discharge channels that are under construction and form due to the applied high external field strengths. An assembly of such streamer takes place within less than 10 ns and then rapidly merges into a thermal breakdown channel.
  • the pulse duration is significantly shorter than corresponds to a construction time of a complete breakdown in the respective medium.
  • short high voltage pulses has been found to be particularly advantageous, whereas the use of radio frequency (RF) or microwave pulses or high voltage single pulses of more than 10 ⁇ s in duration, as in US Pat WO 2004/101891 A1 described, is far less efficient. The reason probably lies in the rapid transition from streamer to atmospheric pressure breakdown, especially in the presence of geometric irregularities on the paper surface, such as single fibers where the electric field is greatly exaggerated.
  • the paper web or the fiber suspension is located between the electrodes used for the streamer discharge, this is particularly advantageous since the paper or the fiber suspension thereby acts in part as a dielectric barrier.
  • the dielectric barrier makes it easier to control the transition from the streamer to the breakdown.
  • FIG. 1 shows a schematic representation of a papermaking plant 1, as used in today's paper mills. Their construction and the combination of different aggregates are determined by the type of paper, board and paperboard types to be produced, as well as the raw materials used.
  • the papermaking plant 1 has a spatial extent of about 10 m in width and about 120 m in length.
  • the papermaking plant produces up to 1400 m of paper per minute 27. It only takes a few seconds from the first impingement of the fiber suspension or pulp 39 on the screening device 9 to the finished paper 27, which is finally rolled out in a reel 15. Diluted with water at a ratio of 1: 100, the fibrous materials are applied together with auxiliaries to the sieve device 9 with the sieve 10.
  • the fibers are deposited on the screen 10 side by side and on each other.
  • the white water 23 can drain or be sucked off by means of several suction chamber regions 24.
  • a uniform fiber composite which is further dehydrated by mechanical pressure in a press device 11 and with the aid of steam heat.
  • the entire papermaking process is essentially subdivided into the areas of stock preparation, paper machine, finishing and equipment.
  • the headbox 7 of the papermaking plant 1 distributes the pulp suspension uniformly over the entire wire width.
  • the paper web 27 still contains about 80% water.
  • Another dewatering process is carried out by mechanical pressure in the press device 11.
  • the paper web 27 is guided by means of an absorbent endless felt cloth between rolls of steel, granite or hard rubber and thereby dehydrated.
  • the white water 23 taken up by the suction chamber region 24 is fed to a sorter 5 in part and returned to another part to a fabric scavenger 17.
  • the press device 11 is followed by a drying system 13.
  • the remaining residual water is evaporated in the drying plant 13.
  • Slalom-like, the paper web 27 passes through several steam-heated drying cylinders. In the end, the paper 27 has a residual moisture of a few percent.
  • the water vapor formed in the drying plant 13 is sucked off and passed into a heat recovery system, not shown.
  • a large-volume plasma with a high power density is produced by superposing intensive, short-duration high-voltage pulses having a high pulse repetition rate of 1 kHz on a DC corona discharge.
  • a very homogeneous, large volume, high power density plasma is created between a first electrode 47 and a second electrode 48 without the plasma constrictions known in DC corona discharges.
  • a treatment of the fiber suspension 39 can also be carried out according to the method of the invention between the headbox 7 and the beginning region of the sieve device 9 with a first electrode 43 under the sieve device 9 and a second electrode 44 above the sieve device 9.
  • the electrodes 43 and 44 are arranged such that the surface-distributed fiber suspension 39 extends between the electrodes. So that a large-area plasma under atmospheric pressure in the immediate vicinity of the fiber suspension 39 can be produced for the treatment of the fiber suspension 39, the electrodes 43 and 44 are connected to a high-voltage pulse generator 46. With the aid of this high-voltage pulse generator 46, a large-volume plasma with a large cross section and with high power density is produced between the electrodes 43 and 44. Here, a plasma density is homogeneously distributed over the treatment area which is covered by the electrodes 43 and 44.
  • a large-area plasma for the treatment of the paper web 27 is produced with the electrode system 47 and 48 in the press device 11 according to the invention.
  • the first electrode 47 in the press apparatus 11 is designed as a semicircular grid electrode. Due to the semicircular configuration of the electrode 47, it can follow the course of the paper web over a transport roller 12.
  • the second electrode 48 in the press device 11 is configured as a plate electrode and arranged such that the transport roller 12 can be guided between the electrodes 47 and 48.
  • the plasma treatment area is flown via the gas distributor 81 with the gas line 80 with an oxygen-argon mixture. Hydroxyl radicals are particularly advantageously produced with the aid of the oxygen-argon mixture.
  • the pressing process compacts the paper structure, the strength is increased again and a surface quality is decisively influenced.
  • the molecular structure of the paper surface is further altered.
  • printability is improved.
  • a streamer is a special form of a linearly moving plasma cloud or a developing discharge channel that forms due to the excited high external field strength. An assembly of such streamer takes place within less than 10 ns and merges very quickly into a thermal breakdown channel.
  • the radicals OH By direct treatment of the pulp fiber suspension 39 or 27 of the paper with the cold plasma in the suspension 39 or in the paper 27, the radicals OH, preferably -, HOO -, O, O 3 produced. Among other things, these radicals trigger a bleaching chemical reaction.
  • the high voltage pulse generator 46 is operated to generate high voltage pulses having a duration of typically 1 ⁇ s between the electrodes 43 and 44.
  • a necessary for the generation of radicals and ozone in the pulp fiber suspension DC voltage is about a few 10 kV to about 100 kV.
  • the high voltage pulses are superimposed on the DC voltage and thus form a total amplitude of typically about 100 kV.
  • the radicals By treating the pulp fiber suspension 39 with a cold electrical discharge, so the plasma, the radicals are generated in situ. Thus, large total amounts of radicals can be introduced into the suspension 39.
  • the high voltage pulse generator is operated to generate high voltage pulses having a duration of typically 0.1 ⁇ s to a few ⁇ s.
  • FIG. 2 shows as a further embodiment, a sectional view of an arrangement for generating radicals.
  • a high voltage electrode 50 is arranged in the center of the arrangement.
  • the outer jacket of the assembly is prepared as a counter electrode 51.
  • a Pulp fiber suspension 39 is prepared in the arrangement.
  • the streamer formation is illustrated using the example of this arrangement.
  • a streamer 53 is shown between the electrodes 50 and 51. Radicals are generated in streamers by high-energy electrons colliding with and dissociating or exciting molecules. Upon dissociation, radicals 59 are immediately released, while upon excitation by a subsequent radiant transition, UV light is generated. This generated UV light in turn reacts with water molecules and dissociates them.
  • FIG. 3 is the applied voltage waveform of the high voltage pulses shown.
  • a first pulse 66 and a second pulse 67 each having a pulse width 62, have a spacing of one pulse repetition time 63.
  • the abscissa shows the time in ms and the ordinate the voltage in kV. The units are chosen arbitrarily.
  • a level of typically about 100 kV DC voltage coincides with the abscissa shown.
  • the illustrated pulse voltage is thus superimposed on the DC voltage.
  • the pulses 66 and 67 have a pulse width 62 of less than 1 ⁇ s, wherein the individual pulses 66, 67 a steeply rising edge with a rise time 64 and a less steeply falling edge.
  • the pulse repetition time 63 is typically between 10 ⁇ s and 100 ms.
  • the individual pulses 66, 67 have such a total amplitude that a predefined energy density is achieved beyond the predetermined direct voltage.
  • the pulse rise time 64 is short compared to the pulse fall time.
  • FIG. 4 shows examples of electrode systems for generating corona discharges in preferably aqueous media.
  • FIG. 4 is a plate-plate arrangement of one first plate 70a as an electrode and a second plate 70b as an electrode.
  • the first plate 70a and the second plate 70b are arranged parallel to each other.
  • the first plate 70a forms the high voltage electrode and is connected to the high voltage pulse generator 46 via a high voltage cable.
  • the second plate 70b forms the counter electrode and is connected as a grounded electrode to the high voltage pulse generator 46 in connection.
  • FIG. 5 A corresponding arrangement with specially flat plate electrodes is in FIG. 5 shown. Again there are two solid plate electrodes 70a and 70c at a fixed distance with a high voltage electrode 71 in the middle.
  • the high voltage electrode 71 is made of a solid wire and connected to the high voltage output of the high voltage pulse generator 46.
  • the grounded plates 70a, 70c are also in communication with the high voltage pulse generator.
  • FIG. 6 shows a wire-tube arrangement as an electrode system.
  • a high-voltage electrode 71 projects centrally into a cylindrical electrode 72.
  • the high voltage electrode 71 is made as a solid wire and connected to the high voltage pulse generator 46.
  • the cylindrical electrode 72 which is preferably configured as a wire mesh, is grounded and communicates with the high voltage pulse generator 46.
  • FIG. 7 shows a tip-plate assembly as an electrode system.
  • Three tips 73 are connected to the high voltage pulse generator 46 via a high voltage line.
  • the tips 73 are arranged at right angles to a grounded plate electrode 74.
  • the distance of the tip electrodes 73 to the plate electrode 74 is adjustable and thus can be adapted for different process conditions.
  • FIG. 8 shows an electrode system assembly comprising 3 plates 70a, 70d and 70e.
  • the first plate 70 a which as High voltage electrode connected to the high voltage pulse generator -46 is centrally located between two solid plates 70d and 70e.
  • the plates 70a and 70b are connected via a plate connector 70f. Since the plate 70d as a grounded counter electrode is in communication with the high voltage pulse generator 46, the plate 70e above the plate connector 70f also functions as a grounded counter electrode.
  • FIG. 9 shows an electrode system as a grid-grid arrangement. Analogous to FIG. 4 Here, a first grid 75a and a second grid 75b are parallel to each other.
  • the first grid 75a forms the high voltage electrode and is connected to the high voltage pulse generator 46.
  • the second grid 75b forms the grounded counter electrode and communicates with the high voltage pulse generator 46.
  • a hybrid discharge wherein an electrode 75a is located entirely outside a fiber suspension 39 to be treated and a second electrode 75b is wholly or partially immersed in the fiber suspension 39 is provided with an alternative arrangement in which the screen is configured as electrode 75a is generated.
  • the screen is designed as a grid electrode and forms the high voltage electrode which is connected to the high voltage pulse generator 46.
  • the grounded counter electrode 76 b is designed as a grid electrode and is in communication with the high voltage pulse generator 46.
  • FIG. 10 is that out FIG. 1 known schematic press apparatus 11 enlarged and shown in more detail.
  • the paper 27 is agitated via numerous transport rollers and rollers by the press device 11 and thereby increasingly dewatered and compacted.
  • the press apparatus On the exact function and operation of the press apparatus will not be discussed in more detail, since the person skilled in a press device without the electrode assembly according to the invention is known.
  • the electrodes 47 and 48 which form a plasma reactor within the press device 11, are arranged.
  • the electrodes 47 and 48 are connected to the high voltage pulse generator 46.
  • a plasma is generated between the electrodes 47, 48 as already described above.
  • the paper web 27 extends between the electrodes 47,48 and is treated on both sides with plasma.
  • the paper web 27 forms a dielectric barrier already described and can thus favor the streamer formation.
  • the electrode 12a is configured as a roller electrode, similar to the roller electrode in FIG FIG. 11 ,
  • the paper 27 is guided by the roller electrode 12a.
  • a plasma for the treatment of the paper 27 is generated by means of the high-voltage generator 46 connected to them.
  • the transport roller 12 represents the grounded counterelectrode 12a.
  • the paper 27 is guided by the transport roller 12 in a force-fit and form-locking manner.
  • a likewise grounded counter electrode 12c which follows the course of the transport roller 12 in a semicircular manner, is electrically connected in a manner not shown to the transport roller 12, in particular to the roller electrode 12a.
  • an electrode arrangement is formed with a constant spacing, in which the individual wires 12b to 12b n are arranged centrally.
  • the paper to be processed runs 27 and is thus applied to each of the arranged between the two electrodes 12a and 12c wires 12b to 12b n with plasma and / or gas discharge.
  • the arrangement is also referred to as a curved wire-plate arrangement which forms a plasma reactor.

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Description

Die Erfindung betrifft eine Pressenvorrichtung zum Verdichten von Papier und/oder zum Entziehen von Trägerflüssigkeit aus feuchten Papier, Pappe oder Karton bei der Herstellung von Papier, Pappe oder Karton, wobei die Pressenvorrichtung einer Siebvorrichtung nachgeordnet und vor einer Trocknungsanlage angeordnet ist.The invention relates to a press device for compacting paper and / or for removing carrier liquid from wet paper, cardboard or cardboard in the manufacture of paper, cardboard or cardboard, wherein the press device is arranged downstream of a screening device and arranged in front of a drying plant.

Des Weiteren betrifft die Erfindung ein Verfahren zum Betrieb der Pressenvorrichtung nach der Erfindung beim Verdichten von Papier und/oder Entziehen von Trägerflüssigkeit aus feuchten Papier, Pappe oder Karton bei der Herstellung von Papier, Pappe oder Karton, wobei die Pressenvorrichtung einer Siebvorrichtung nachgeordnet und vor einer Trocknungsanlage angeordnet ist.Furthermore, the invention relates to a method for operating the press apparatus according to the invention in the compression of paper and / or removal of carrier liquid from wet paper, cardboard or paperboard in the manufacture of paper, paperboard or cardboard, wherein the press device downstream of a screening device and before a Drying system is arranged.

In einer Papierherstellungsanlage oder in Teilen einer Papierherstellungsanlage verlässt ein, in der Regel noch feuchtes Papier, Pappe oder Karton einen Siebbereich der Papierherstellungsanlage und gelangt von dort in einen Pressenbereich der Papierherstellungsanlage. Im Pressenbereich wird das Papier, Pappe oder der Karton entwässert. Stellvertretend für Papier, Pappe oder Karton wird nachfolgend der Begriff Papier oder Prozessgut verwendet.In a paper manufacturing plant or in parts of a papermaking plant leaves a, usually still wet paper, cardboard or cardboard a screening area of the papermaking plant and from there into a press area of the papermaking plant. In the press area, the paper, cardboard or cardboard is drained. The term paper or process material is used below to represent paper, cardboard or paperboard.

Eine Festigkeit des Papiers nimmt mit zunehmender Entwässerung zu. Papierfasern bestehen vorzugsweise aus vielen Zelluloseketten mit vielen OH-Gruppen. Die Festigkeit des Papiers entsteht über dazwischen liegende Wassermoleküle, die die Fasern über Wasserstoffbrücken miteinander verbinden. Die Anzahl der Wasserstoffbrücken kann durch Pressung oder leichte Streckung gesteigert werden.Strength of the paper increases with increasing drainage. Paper fibers preferably consist of many cellulose chains with many OH groups. The strength of the paper is created by intervening water molecules, which connect the fibers via hydrogen bonds. The number of hydrogen bonds can be increased by compression or slight stretching.

Aus WO 2004/101891 A1 ist ein Verfahren zur Behandlung von Papier mit Plasma bekannt.Out WO 2004/101891 A1 For example, a method of treating paper with plasma is known.

Aus DE 198 36 669 A1 ist ein Verfahren zur Oberflächenvorbehandlung am festen trockenen Papier bekannt.Out DE 198 36 669 A1 For example, a method for surface pretreatment on solid dry paper is known.

Den beiden Druckschriften ist nicht zu entnehmen, wie, im Hinblick auf eine Festigkeitssteigerung des Papiers zum Zweck einer Erhöhung einer Prozessgeschwindigkeit, dass Papier zu behandeln ist.It can not be inferred from the two documents how, in view of increasing the strength of the paper for the purpose of increasing a process speed, paper is to be treated.

Der Erfindung liegt die Aufgabe zugrunde, eine Vorrichtung und ein Verfahren zur Verfügung zu stellen, um die Verarbeitungsgeschwindigkeit bei der Papierherstellung zu steigern.The invention has for its object to provide an apparatus and a method to increase the processing speed in papermaking.

Die vorrichtungsbezogene Aufgabe wird gemäß der Erfindung dadurch gelöst, dass über in oder unter einem Pressbereich der Pressenvorrichtung mindestens eine erste Elektrode angeordnet ist, welche mit einem Hochspannungsimpulsgenerator verbunden ist, wobei im/am feuchten Papier, Pappe oder Karton oder in seiner/dessen unmittelbaren Umgebung ein Plasma erzeugbar ist.The device-related object is achieved according to the invention in that at least one first electrode, which is connected to a high-voltage pulse generator, is arranged in or under a pressing region of the press device, in / on the wet paper, cardboard or cardboard or in its immediate vicinity a plasma can be generated.

Durch die Behandlung des noch feuchten Papiers bzw. der Fasern in der Pressenvorrichtung noch vor einer ersten Trockenstufe mit einem vorzugsweise kalten Koronaplasma, wird die molekulare Struktur der Papieroberfläche bzw. der Fasern verändert. Durch die Behandlung mit Plasma wird die Festigkeit des "Blattes" noch vor der ersten Trockenstufe erhöht. Vorzugsweise wird das Plasma in einem Abstand von kleiner als 20 cm, vorzugsweise kleiner als 10 cm, vorzugsweise kleiner als 5 cm, von dem noch feuchten Papier in der Pressenvorrichtung erzeugt.By treating the still moist paper or fibers in the press apparatus before a first drying stage with a preferably cold corona plasma, the molecular structure of the paper surface or of the fibers is changed. Treatment with plasma increases the strength of the "sheet" even before the first drying stage. Preferably, the plasma is generated at a distance of less than 20 cm, preferably less than 10 cm, preferably less than 5 cm from the still wet paper in the press apparatus.

In weiterer Ausgestaltung der Erfindung ist eine Transportrolle als eine erste Elektrode hergerichtet. Durch die direkte Behandlung mit vorzugsweise kaltem Plasma in der Pressenvorrichtung mittels einer Transportrolle werden im Papier mehr Wasserstoffbrückenbindungen als ohne die Plasmabehandlung gebildet. Die Festigkeit des Papiers in der Pressenvorrichtung nimmt daher zu. Die Steigerung der Festigkeit des Papiers reduziert die Gefahr von Papierrissen und eröffnet somit die Möglichkeit die Verarbeitungsgeschwindigkeit der Papierherstellungsanlage zu erhöhen.In a further embodiment of the invention, a transport roller is prepared as a first electrode. As a result of the direct treatment with preferably cold plasma in the press apparatus by means of a transport roller, more hydrogen bonds are formed in the paper than without the plasma treatment. The strength of the paper in the press apparatus therefore increases. Increasing the strength of the Paper reduces the risk of paper tears and thus opens up the possibility of increasing the processing speed of the paper production line.

Zweckmäßig ist es, dass mindestens eine zweite Elektrode zur Plasmaerzeugung vorhanden ist. Zwischen den beiden Elektroden wird das Plasma, vorzugsweise als eine Koronaentladung oder eine Gasentladung, erzeugt. Durch diese Art der Anordnung wird das Papier zwischen den beiden Elektroden geführt und kann so gezielt mit Plasma behandelt werden.It is expedient that at least one second electrode for plasma generation is present. Between the two electrodes, the plasma is generated, preferably as a corona discharge or a gas discharge. Due to this type of arrangement, the paper is guided between the two electrodes and can thus be treated specifically with plasma.

Mit Vorteil ist mindestens eine Elektrode als Platte ausgestaltet. Mit der vörzugsweisen Ausgestaltung einer Elektrode als Platte wird das gezielte Applizieren mit Plasma auf das Papier um ein weiteres erhöht.Advantageously, at least one electrode is designed as a plate. With the preferred embodiment of an electrode as a plate, the targeted application of plasma to the paper is increased by one more time.

Weitere bevorzugte Ausgestaltungsmerkmale der Pressenvorrichtung, insbesondere der Elektrodenanordnungen der Pressenvorrichtung, sind durch die Patentansprüche 5 bis 11 wiedergegeben.Further preferred design features of the press device, in particular the electrode arrangements of the press device, are represented by the claims 5 to 11.

Eine weitere Steigerung der Festigkeit wird durch ein Mittel zum Einleiten von Gas, insbesondere Luft oder Sauerstoff, vorzugsweise reinem Sauerstoff oder Sauerstoff mit beispielsweise Edelgas als Trägergas, zwischen oder in die unmittelbare Nähe der Elektroden erreicht. Mit Hilfe dieses eingeströmten Gases und der gleichzeitigen Behandlung mit Plasma wird die spätere Reißfestigkeit des Papiers weiter erhöhtA further increase in strength is achieved by a means for introducing gas, in particular air or oxygen, preferably pure oxygen or oxygen with, for example, noble gas as the carrier gas, between or in the immediate vicinity of the electrodes. With the help of this infused gas and the simultaneous treatment with plasma, the subsequent tear strength of the paper is further increased

Nach der verfahrensseitigen Maßgabe der Erfindung ist vorgesehen, dass das zu verdichtende Papier mit vorzugsweise nichtthermischen, großflächigem Plasma unter Atmosphärendruck in Kontakt gebracht, das Plasma in unmittelbarer Nähe zum Papier erzeugt oder in dem Papier oder in seiner unmittelbaren Umgebung eine Gasentladung, insbesondere eine Koronaentladung, unter Atmosphärendruck erzeugt wird.According to the procedural aspect of the invention, it is provided that the paper to be compacted is brought into contact with preferably non-thermal, large-area plasma under atmospheric pressure, the plasma is produced in the immediate vicinity of the paper or in the paper or in its immediate vicinity a gas discharge, in particular a corona discharge, is generated under atmospheric pressure.

In weiterer vorteilhafter Ausgestaltung der Erfindung werden zur Erzeugung des Plasmas bzw. der Gasentladung zwischen Elektroden Hochspannungsimpulse mit einer Dauer von weniger als 10 µs erzeugt. Die Verwendung von Hochspannungsimpulsen, welche eine Dauer von weniger als 10 µs haben, hat sich - wie später noch beschrieben wird - als besonders vorteilhaft herausgestellt.In a further advantageous embodiment of the invention, high-voltage pulses having a duration of less than 10 μs are generated between electrodes to produce the plasma or the gas discharge. The use of high voltage pulses, which have a duration of less than 10 microseconds, has been found to be particularly advantageous, as will be described later.

Bei der Behandlung der noch nicht vollständig getrockneten Papieroberfläche mit kaltem Plasma, vorzugsweise unmittelbar vor der ersten Trockenstufe, werden bestimmte Radikale erzeugt (z.B. OH-, HOO-, O, O3), welche mit der Papieroberfläche und insbesondere den noch nicht vollständig gebundenen Fasern chemisch reagieren.In the treatment of the as yet incompletely dried paper surface with cold plasma, preferably immediately before the first drying step, certain radicals are generated (eg OH - , HOO - , O, O 3 ), which interfere with the paper surface and in particular the not yet fully bonded fibers react chemically.

Weitere bevorzugte Verfahrensmerkmale sind durch die Patentabsprüche 15 bis 43 beschrieben. Diesen liegen unter anderem folgende Überlegungen zu Grunde:Further preferred method features are described by patent claims 15 to 43. These are based inter alia on the following considerations:

Radikale können unter anderem auch bleichende chemische Reaktionen auslösen, insbesondere freier Sauerstoff O, insbesondere auch ein Hydroxyl-Radikal OH, insbesondere Ozon O3, als auch freie funktionelle Gruppen wie z.B. OH-Gruppen, COOH-Gruppen. Diese funktionalen Gruppen wiederum sind maßgeblich daran beteiligt, insbesondere die Bindungsfestigkeit der Fasern untereinander zu erhöhen, wodurch sich die Reißfestigkeit des Papiers erhöht und damit die Verarbeitungsgeschwindigkeit weiter gesteigert werden kann.Radicals may, inter alia, also trigger bleaching chemical reactions, in particular free oxygen O, in particular also a hydroxyl radical OH, in particular ozone O 3 , as well as free functional groups such as OH groups, COOH groups. In turn, these functional groups are instrumental in increasing, in particular, the bond strength of the fibers to one another, thereby increasing the tear strength of the paper and thus further increasing the processing speed.

Vorzugsweise wird bei einer simultanen Erzeugung von Radikalen eine Reihe von unterschiedlich oxidierenden und funktionalisierenden Radikalen in einer Gasphase erzeugt und dazu verwendet, im nicht vollständig getrocknetem Blatt, in der Pressenvorrichtung oder unmittelbar danach das Papier mit Radikalen zu behandeln.Preferably, with simultaneous generation of radicals, a series of different oxidizing and functionalizing radicals are generated in a gaseous phase and used to treat the paper with radicals in the incompletely dried sheet, in the press apparatus or immediately thereafter.

Insbesondere soll diese Behandlung bei einem Gehalt an Trägerflüssigkeit von 2 % bis zu über 30 % eingesetzt werden.In particular, this treatment should be used at a content of carrier liquid of 2% to more than 30%.

Die Festigkeit des Papiers und damit die maximale mögliche Arbeitsgeschwindigkeit wird dadurch schon vor einer Trocknungsanlage erhöht. Des Weiteren lassen sich durch diese Art der Behandlung auch die an der Oberfläche liegenden farbigen Stoffe bleichen, beispielsweise werden das anhaftende Lignin oder Farbstoffreste oxidativ entfärbt.The strength of the paper and thus the maximum possible working speed is thereby increased even before a drying plant. Furthermore, this type of treatment also bleaches the colored substances lying on the surface, for example the adhering lignin or dye residues are oxidatively decolorized.

Radikale werden in Gasentladungen dadurch erzeugt, dass energiereiche Elektronen mit Molekülen zusammenstoßen und diese dadurch dissoziieren oder anregen und so zur Radikalenbildung führen. Bei der Dissoziation werden unmittelbar Radikale freigesetzt, während bei der Anregung durch anschließende strahlende Übergänge UV-Licht erzeugt wird, welches wiederum mit vorzugsweise Luft- und Wassermolekülen reagiert und diese dissoziiert. Um ausreichend energiereiche Elektronen im Bereich von ca. 5 eV (Elektronenvolt) bis > 15 eV zu erhalten, werden hohe elektrische Felder benötigt. Diese hohen Feldstärken treten insbesondere am Kopf von sogenannten Streamern auf. Streamer sind Entladungskanäle, die sich im Aufbau befinden und sich aufgrund der angelegten hohen externen Feldstärken ausbilden. Ein Aufbau solcher Streamer findet innerhalb weniger 10 ns statt und geht dann schnell in einen thermischen Durchschlagskanal über. Da in einem thermischen Durchschlagskanal keine energiereichen Elektronen gebildet werden, ist es unter anderem das Ziel, diese thermischen Durchschläge zu vermeiden oder auf ein Minimum zu reduzieren. Um eine gute Energieeffizienz der Erzeugung von vorzugsweise Radikalen in Gasen zu erhalten, ist es daher erforderlich, mit sehr kurzen Hochspannungseinzelimpulsen zu arbeiten. Vorzugsweise ist die Pulsdauer deutlich kürzer als es einer Aufbauzeit eines vollständigen Durchschlages im jeweiligen Medium entspricht.Radicals are generated in gas discharges by the fact that high-energy electrons collide with molecules and thereby dissociate or excite them and thus lead to the formation of radicals. In the dissociation, radicals are released immediately, while in the excitation by subsequent radiant transitions UV light is generated, which in turn reacts with and preferably dissociates air and water molecules. To obtain sufficiently high-energy electrons in the range from about 5 eV (electron volts) to> 15 eV, high electric fields are required. These high field strengths occur in particular at the head of so-called streamers. Streamer are discharge channels that are under construction and form due to the applied high external field strengths. An assembly of such streamer takes place within less than 10 ns and then rapidly merges into a thermal breakdown channel. Since no high-energy electrons are formed in a thermal breakdown channel, among other things, the goal is to avoid these thermal breakdowns or to reduce them to a minimum. In order to obtain a good energy efficiency of the generation of preferably radicals in gases, it is therefore necessary to work with very short single high-voltage pulses. Preferably, the pulse duration is significantly shorter than corresponds to a construction time of a complete breakdown in the respective medium.

Eine gepulste Koronaentladung direkt oberhalb des Papiers oder an dem noch feuchten Papier unter Benutzung kurzer Hochspannungsimpulse von weniger als 10 µs, insbesondre typisch von 1 µs, und besonders vorteilhaft deutlich geringer als 1 µs, mit Spannungen von einigen kV bis zu über 100 kV, abhängig von einem Abstand der Elektroden zum Papier und der Eigenschaften des Papiers, wird mit Vorteil, hinsichtlich der Qualitätseigenschaften, auf das Papier appliziert. Insbesondere hat sich die Verwendung von derartig kurzen Hochspannungsimpulsen als besonders vorteilhaft gezeigt, wogegen die Verwendung von Radiofrequenz-(RF-) oder Mikrowellenimpulsen oder von Hochspannungseinzelimpulsen mit mehr als 10 µs Dauer, wie in WO 2004/101891 A1 beschrieben, weit weniger effizient ist. Der Grund liegt vermutlich in dem schnellen Übergang vom Streamer zum Durchschlag bei Atmosphärendruck, insbesondere bei Vorhandensein von geometrischen Irregularitäten an der Papieroberfläche, wie z.B. einzelne Fasern, an denen das elektrische Feld erheblich überhöht ist.A pulsed corona discharge directly above the paper or on the still wet paper using short high voltage pulses of less than 10 μs, more typically of 1 μs, and most advantageously significantly less than 1 μs, with voltages of a few kV to over 100 kV From a distance of the electrodes to the paper and the properties of the paper, is applied with advantage, in terms of quality properties, on the paper. In particular, the use of such short high voltage pulses has been found to be particularly advantageous, whereas the use of radio frequency (RF) or microwave pulses or high voltage single pulses of more than 10 μs in duration, as in US Pat WO 2004/101891 A1 described, is far less efficient. The reason probably lies in the rapid transition from streamer to atmospheric pressure breakdown, especially in the presence of geometric irregularities on the paper surface, such as single fibers where the electric field is greatly exaggerated.

Befindet sich die Papierbahn oder die Faser-Suspension zwischen den zur Streamerentladung benutzten Elektroden, so ist dies besonders vorteilhaft, da das Papier oder die Faser-Suspension dadurch teilweise als eine dielektrische Ba.rriere wirkt. Durch die dielektrische Barriere lässt sich der Übergang vom Streamer zum Durchschlag besser kontrollieren.If the paper web or the fiber suspension is located between the electrodes used for the streamer discharge, this is particularly advantageous since the paper or the fiber suspension thereby acts in part as a dielectric barrier. The dielectric barrier makes it easier to control the transition from the streamer to the breakdown.

Bevorzugte, jedoch keinesfalls einschränkende Ausführungsbeispiele der Erfindung werden nunmehr anhand der Zeichnung näher erläutert. Zur Verdeutlichung ist die Zeichnung nicht maßstäblich ausgeführt, und gewisse Merkmale sind nur schematisiert dargestellt. Einander entsprechende Teile sind in den Figuren mit denselben Bezugszeichen versehen. Im Einzelnen zeigt die

FIG 1
eine schematische Darstellung einer Papierherstellungsanlage mit einer Siebvorrichtung, einer Pressenvorrichtung nach der Erfindung und einer Veredelungsund/oder Trockenanlage,
FIG 2
eine Darstellung (Schnitt) einer Anordnung zur Erzeugung von Radikalen in Koronaplasmen in Pulpe oder Luft: Parallelplatten- oder Rohranordnung mit Draht, dem eine gepulste Hochspannung überlagert wird,
FIG 3
eine Prinzipdarstellung von Impulsen zur Erzeugung von Radikalen in Koronaentladungen in Luft oder wässrigen Medien bei Einsatz kurzer (typisch < 1 µs) Hochspannungsimpulse mit hoher Impulswiederholrate,
FIG 4
bis FIG 9 Elektrodenanordnungen und Elektrodensysteme zur Erzeugung von Koronaentladungen: Platte-Platte-, Platte-Draht-Platte-, koaxiale Draht-Rohr-, Spitze-Platte-, Mehrfachspitzen-Platte-, Gitter-Platte (Rohr)-, Gitter-Gitter-Anordnungen.
FIG 10
eine Pressenvorrichtung mit erfindungsgemäßen Elektrodenanordnungen zur Plasmabehandlung, und
FIG 11
eine Transportrolle als Elektrode.
Preferred, but by no means limiting embodiments of the invention will now be explained in more detail with reference to the drawing. For clarity, the drawing is not drawn to scale, and certain features are shown only schematically. Corresponding parts are provided in the figures with the same reference numerals. In detail, the shows
FIG. 1
a schematic representation of a papermaking plant with a screening device, a press device according to the invention and a finishing and / or drying plant,
FIG. 2
a representation (section) of an arrangement for generating radicals in corona plasmas in pulp or air: parallel plate or tube arrangement with wire, which is superimposed on a pulsed high voltage,
FIG. 3
a schematic diagram of pulses for generating radicals in corona discharges in air or aqueous media using short (typically <1 μs) high voltage pulses with high pulse repetition rate,
FIG. 4
to FIG. 9 Electrode assemblies and electrode systems for generating corona discharges: plate-plate, plate-wire-plate, coaxial-wire-tube, tip-plate, multi-tip-plate, grid-plate (tube), grid-grid assemblies.
FIG. 10
a press apparatus with electrode arrangements according to the invention for plasma treatment, and
FIG. 11
a transport roller as an electrode.

FIG 1 zeigt eine schematische Darstellung einer Papierherstellungsanlage 1, wie sie in heutigen Papierfabriken eingesetzt wird. Ihre Konstruktion und die Kombination unterschiedlicher Aggregate werden von der Art der zu erzeugenden Papier-, Karton- und Pappesorten sowie der eingesetzten Rohstoffe bestimmt. Die Papierherstellungsanlage 1 hat eine räumliche Ausdehnung von ungefähr 10 m in der Breite und ungefähr 120 m in der Länge. Pro Minute produziert die Papierherstellungsanlage bis zu 1400 m Papier 27. Es dauert nur wenige Sekunden vom ersten Auftreffen der Faser-Suspension oder der Pulpe 39 auf die Siebvorrichtung 9 bis zum fertigen Papier 27, welches letztendlich in einer Aufrollung 15 augerollt wird. Im Verhältnis 1:100 mit Wasser verdünnt, werden die Faserstoffe zusammen mit Hilfsstoffen auf die Siebvorrichtung 9 mit dem Sieb 10 aufgebracht. Die Fasern lagern sich auf dem Sieb 10 neben- und aufeinander ab. Das Siebwasser 23 kann mittels mehrerer Saugkammerbereiche 24 abfließen oder abgesaugt werden. Auf diese Weise entsteht ein gleichmäßiger Faserverbund, der durch mechanischen Druck in einer Pressenvorrichtung 11 und mit Hilfe von Dampfwärme weiter entwässert wird. Der gesamte Papierherstellungsprozess unterteilt sich dabei im Wesentlichen in die Bereiche Stoffaufbereitung, Papiermaschine, Veredelung und Ausrüstung. FIG. 1 shows a schematic representation of a papermaking plant 1, as used in today's paper mills. Their construction and the combination of different aggregates are determined by the type of paper, board and paperboard types to be produced, as well as the raw materials used. The papermaking plant 1 has a spatial extent of about 10 m in width and about 120 m in length. The papermaking plant produces up to 1400 m of paper per minute 27. It only takes a few seconds from the first impingement of the fiber suspension or pulp 39 on the screening device 9 to the finished paper 27, which is finally rolled out in a reel 15. Diluted with water at a ratio of 1: 100, the fibrous materials are applied together with auxiliaries to the sieve device 9 with the sieve 10. The fibers are deposited on the screen 10 side by side and on each other. The white water 23 can drain or be sucked off by means of several suction chamber regions 24. In this way, a uniform fiber composite, which is further dehydrated by mechanical pressure in a press device 11 and with the aid of steam heat. The entire papermaking process is essentially subdivided into the areas of stock preparation, paper machine, finishing and equipment.

Der Stoffauflauf 7 der Papierherstellungsanlage 1 verteilt die Faserstoff-Suspension gleichmäßig über die gesamte Siebbreite. Am Ende der Siebvorrichtung 9 enthält die Papierbahn 27 noch immer ca. 80 % Wasser.The headbox 7 of the papermaking plant 1 distributes the pulp suspension uniformly over the entire wire width. At the end of the screening device 9, the paper web 27 still contains about 80% water.

Ein weiterer Entwässerungsprozess erfolgt durch mechanischen Druck in der Pressenvorrichtung 11. Dabei wird die Papierbahn 27 mittels eines saugfähigen endlosen Filztuches zwischen Walzen aus Stahl, Granit oder Hartgummi hindurchgeführt und dadurch entwässert. Das durch den Saugkammerbereich 24 aufgenommene Siebwasser 23 wird zu einem Teil zu einem Sortierer 5 zugeführt und zu einem anderen Teil zu einem Stofffänger 17 zurückgeführt. An die Pressenvorrichtung 11 schließt sich eine Trocknungsanlage 13 an. Das verbleibende Restwasser wird in der Trocknungsanlage 13 verdampft. Slalomartig durchläuft die Papierbahn 27 mehrere dampfbeheizte Trockenzylinder. Am Ende hat das Papier 27 eine Restfeuchte von wenigen Prozent. Der in der Trocknungsanlage 13 entstandene Wasserdampf wird abgesaugt und in eine nicht dargestellte Wärmerückgewinnungsanlage geführt.Another dewatering process is carried out by mechanical pressure in the press device 11. In this case, the paper web 27 is guided by means of an absorbent endless felt cloth between rolls of steel, granite or hard rubber and thereby dehydrated. The white water 23 taken up by the suction chamber region 24 is fed to a sorter 5 in part and returned to another part to a fabric scavenger 17. The press device 11 is followed by a drying system 13. The remaining residual water is evaporated in the drying plant 13. Slalom-like, the paper web 27 passes through several steam-heated drying cylinders. In the end, the paper 27 has a residual moisture of a few percent. The water vapor formed in the drying plant 13 is sucked off and passed into a heat recovery system, not shown.

Erfindungsgemäß wird ein großvolumige Plasma mit hoher Leistungsdichte dadurch erzeugt, dass einer DC-Korona-Entladung intensive, kurz andauernde Hochspannungsimpulse mit einer hohen Impulswiederholrate von 1 kHz überlagert werden. Bei dieser Betriebsweise wird ein äußerst homogenes, großvolumiges Plasma mit einer hohen Leistungsdichte zwischen einer ersten Elektrode 47 und einer zweiten Elektrode 48 erzeugt, ohne dass es zu den bei DC-Korona-Entladungen bekannten Plasmaeinschnürungen kommt.According to the invention, a large-volume plasma with a high power density is produced by superposing intensive, short-duration high-voltage pulses having a high pulse repetition rate of 1 kHz on a DC corona discharge. In this mode of operation, a very homogeneous, large volume, high power density plasma is created between a first electrode 47 and a second electrode 48 without the plasma constrictions known in DC corona discharges.

Auch eine Behandlung der Faser-Suspension 39 kann nach dem erfindungsgemäßen Verfahren zwischen dem Stoffauflauf 7 und dem Anfangsbereich der Siebvorrichtung 9 mit einer ersten Elektrode 43 unter der Siebvorrichtung 9 und eine zweite Elektrode 44 über der Siebvorrichtung 9 erfolgen. Die Elektroden 43 und 44 sind derart angeordnet, dass die flächig verteilte Faser-Suspension 39 zwischen den Elektroden verläuft. Damit zur Behandlung der Faser-Suspension 39 ein großflächiges Plasma unter Atmosphärendruck in unmittelbarer Nähe zu der Faser-Suspension 39 erzeugt werden kann, sind die Elektroden 43 und 44 mit einem Hochspannungsimpulsgenerator 46 verbunden. Mit Hilfe dieses Hochspannungsimpulsgenerators 46 wird zwischen den Elektroden 43 und 44 ein großvolumiges Plasma mit einem großen Querschnitt und mit hoher Leistungsdichte hergestellt. Hierbei ist eine Plasmadichte homogen über den Behandlungsbereich, welcher durch die Elektroden 43 und 44 abgedeckt wird, verteilt.A treatment of the fiber suspension 39 can also be carried out according to the method of the invention between the headbox 7 and the beginning region of the sieve device 9 with a first electrode 43 under the sieve device 9 and a second electrode 44 above the sieve device 9. The electrodes 43 and 44 are arranged such that the surface-distributed fiber suspension 39 extends between the electrodes. So that a large-area plasma under atmospheric pressure in the immediate vicinity of the fiber suspension 39 can be produced for the treatment of the fiber suspension 39, the electrodes 43 and 44 are connected to a high-voltage pulse generator 46. With the aid of this high-voltage pulse generator 46, a large-volume plasma with a large cross section and with high power density is produced between the electrodes 43 and 44. Here, a plasma density is homogeneously distributed over the treatment area which is covered by the electrodes 43 and 44.

Analog zu dem zuvor beschriebenen wird mit dem Elektrodensystem 47 und 48 in der erfindungsgemäßen Pressenvorrichtung 11 ein großflächiges Plasma zur Behandlung der Papierbahn 27 erzeugt. Die erste Elektrode 47 in der Pressenvorrichtüng 11 ist als eine halbrunde Gitterelektrode ausgeführt. Durch die halbrunde Ausgestaltung der Elektrode 47 kann sie dem Papierbahnverlauf über einer Transportrolle 12 folgen. Die zweite Elektrode 48 in der Pressenvorrichtung 11 ist als eine Plattenelektrode ausgestaltet und derart angeordnet, dass die Transportrolle 12 zwischen den Elektroden 47 und 48 geführt werden kann. Um auch hier die Radikalbildung im Plasma anzuregen, wird der Plasmabehandlungsbereich über den Gasverteiler 81 mit der Gasleitung 80 mit einem Sauerstoff-Argon-Gemisch angeströmt. Mit Hilfe des Sauerstoff-Argon-Gemisches werden besonders vorteilhaft Hydroxyl-Radikale erzeugt.Analogous to that described above, a large-area plasma for the treatment of the paper web 27 is produced with the electrode system 47 and 48 in the press device 11 according to the invention. The first electrode 47 in the press apparatus 11 is designed as a semicircular grid electrode. Due to the semicircular configuration of the electrode 47, it can follow the course of the paper web over a transport roller 12. The second electrode 48 in the press device 11 is configured as a plate electrode and arranged such that the transport roller 12 can be guided between the electrodes 47 and 48. In order to stimulate the formation of radicals in the plasma here as well, the plasma treatment area is flown via the gas distributor 81 with the gas line 80 with an oxygen-argon mixture. Hydroxyl radicals are particularly advantageously produced with the aid of the oxygen-argon mixture.

Der Pressvorgang verdichtet das Papiergefüge, die Festigkeit wird nochmals erhöht und eine Oberflächengüte wird entscheidend beeinflusst. Durch die Behandlung des gepressten Papiers mit kaltem Plasma, insbesondere mit den erzeugten Radikalen, wird die molekulare Struktur der Papieroberfläche weiter verändert. Zusätzlich zur Festigkeit des Papiers 27 wird eine Bedruckbarkeit verbessert.The pressing process compacts the paper structure, the strength is increased again and a surface quality is decisively influenced. By treating the pressed paper with cold plasma, especially with the generated radicals, the molecular structure of the paper surface is further altered. In addition to the strength of the paper 27, printability is improved.

Mit den vorbenannten Elektrodenanordnungen 43 und 44 sowie 47 und 48 ist es nach dem erfindungsgemäßen Verfahren möglich die Papierbahn 27 zwischen Streamer-Entladungen (siehe FIG 2) zu führen. Ein Streamer ist eine spezielle Form einer sich linear fortbewegenden Plasmawolke oder ein in der Entwicklung befindlicher Entladungskanal, der sich aufgrund der angeregten hohen externen Feldstärke ausbildet. Ein Aufbau solcher Streamer findet innerhalb weniger 10 ns statt und geht sehr schnell in einen thermischen Durchschlagskanal über. Vorbenannte Anordnungen der Elektrodensysteme, wobei sich die Papierbahn 27 zwischen den zur Streamer-Entladung benutzten Elektroden befindet ist besonders vorteilhaft, da das Papier 27 dadurch teilweise als eine dielektrische Barriere fungiert, wodurch sich der Übergang vom Streamer zum Durchschlag unterdrücken lässt.With the above-mentioned electrode arrangements 43 and 44 as well as 47 and 48, it is possible according to the inventive method the paper web 27 between streamer discharges (see FIG. 2 ) respectively. A streamer is a special form of a linearly moving plasma cloud or a developing discharge channel that forms due to the excited high external field strength. An assembly of such streamer takes place within less than 10 ns and merges very quickly into a thermal breakdown channel. Afore-mentioned arrangements of the electrode systems, with the paper web 27 between the electrodes used for the streamer discharge, being particularly advantageous, since the paper 27 partially functions as a dielectric barrier, thereby suppressing the transition from the streamer to the breakdown.

Durch eine direkte Behandlung der Zellstofffaser-Suspension 39 oder des Papiers 27 mit dem kalten Plasma werden in der Suspension 39 oder im Papier 27 vorzugsweise die Radikale OH-, HOO-, O, O3 erzeugt. Diese Radikale lösen unter anderem eine bleichende chemische Reaktion aus. Der Hochspannungsimpulsgenerator 46 wird derart betrieben, dass er Hochspannungsimpulse mit einer Dauer von typisch 1 µs zwischen den Elektroden 43 und 44 erzeugt. Eine für die Erzeugung von Radikalen und Ozon in der Zellstofffaser-Suspension notwendige DC-Spannung liegt bei ca. einigen 10 kV bis über 100 kV. Die Hochspannungsimpulse werden der DC-Spannung überlagert und bilden so eine Gesamtamplitude von typisch ca. 100 kV. Durch die Behandlung der Zellstofffaser-Suspension 39 mit einer kalten elektrischen Entladung, also dem Plasma, werden die Radikale in-situ erzeugt. So können große Gesamtmengen von Radikalen in die Suspension 39 eingebracht werden. Für die Elektroden 47 und 48 wird der Hochspannungsimpulsgenerator derart betrieben, dass er Hochspannungsimpulse mit einer Dauer von typisch 0,1 µs bis zu einigen wenigen µs erzeugt.By direct treatment of the pulp fiber suspension 39 or 27 of the paper with the cold plasma in the suspension 39 or in the paper 27, the radicals OH, preferably -, HOO -, O, O 3 produced. Among other things, these radicals trigger a bleaching chemical reaction. The high voltage pulse generator 46 is operated to generate high voltage pulses having a duration of typically 1 μs between the electrodes 43 and 44. A necessary for the generation of radicals and ozone in the pulp fiber suspension DC voltage is about a few 10 kV to about 100 kV. The high voltage pulses are superimposed on the DC voltage and thus form a total amplitude of typically about 100 kV. By treating the pulp fiber suspension 39 with a cold electrical discharge, so the plasma, the radicals are generated in situ. Thus, large total amounts of radicals can be introduced into the suspension 39. For the electrodes 47 and 48, the high voltage pulse generator is operated to generate high voltage pulses having a duration of typically 0.1 μs to a few μs.

FIG 2 zeigt als weiteres Ausführungsbeispiel eine Schnittdarstellung einer Anordnung zur Erzeugung von Radikalen. In der Mitte der Anordnung ist eine Hochspannungselektrode 50 angeordnet. Der Außenmantel der Anordnung ist als eine Gegenelektrode 51 hergerichtet. In der Anordnung befindet sich eine zu siebende Zellstofffaser-Suspension 39. Am Beispiel dieser Anordnung wird die Streamerbildung verdeutlicht. Zwischen den Elektroden 50 und 51 ist ein Streamer 53 dargestellt. Radikale werden in Streamern dadurch erzeugt, dass energiereiche Elektronen mit Molekülen zusammenstoßen und diese dadurch dissoziieren oder anregen. Bei der Dissoziation werden unmittelbar Radikale 59 freigesetzt, während bei der Anregung durch einen anschließenden strahlenden Übergang UV-Licht erzeugt wird. Dieses erzeugte UV-Licht reagiert wiederum mit Wassermolekülen und dissoziiert diese. FIG. 2 shows as a further embodiment, a sectional view of an arrangement for generating radicals. In the center of the arrangement, a high voltage electrode 50 is arranged. The outer jacket of the assembly is prepared as a counter electrode 51. In the arrangement is a Pulp fiber suspension 39 to be screened. The streamer formation is illustrated using the example of this arrangement. Between the electrodes 50 and 51, a streamer 53 is shown. Radicals are generated in streamers by high-energy electrons colliding with and dissociating or exciting molecules. Upon dissociation, radicals 59 are immediately released, while upon excitation by a subsequent radiant transition, UV light is generated. This generated UV light in turn reacts with water molecules and dissociates them.

In FIG 3 ist der applizierte Spannungsverlauf der Hochspannungsimpulse dargestellt. Ein erster Impuls 66 und ein zweiter Impuls 67, mit je einer Impulsbreite 62, weisen einen Abstand von einer Pulswiederholzeit 63 auf. Auf der Abszisse ist die Zeit in ms und auf der Ordinate die Spannung in kV angegeben. Die Einheiten sind willkürlich gewählt. Ein Niveau von typisch ca. 100 kV der DC-Spannung fällt mit der dargestellten Abszisse zusammen. Die dargestellte Impulsspannung ist also der DC-Spannung überlagert. Die Impulse 66 und 67 weisen eine Pulsbreite 62 von kleiner 1 µs auf, wobei die einzelnen Impulse 66, 67 eine steil ansteigende Flanke mit einer Anstiegszeit 64 und einer weniger steil abfallende Flanke auf. Die Impulswiederholzeit 63 liegt typischer Weise zwischen 10 µs und 100 ms.In FIG. 3 is the applied voltage waveform of the high voltage pulses shown. A first pulse 66 and a second pulse 67, each having a pulse width 62, have a spacing of one pulse repetition time 63. The abscissa shows the time in ms and the ordinate the voltage in kV. The units are chosen arbitrarily. A level of typically about 100 kV DC voltage coincides with the abscissa shown. The illustrated pulse voltage is thus superimposed on the DC voltage. The pulses 66 and 67 have a pulse width 62 of less than 1 μs, wherein the individual pulses 66, 67 a steeply rising edge with a rise time 64 and a less steeply falling edge. The pulse repetition time 63 is typically between 10 μs and 100 ms.

Dabei haben die einzelnen Impulse 66,67 eine solche Gesamtamplitude, dass über die vorgegebene Gleichspannung hinaus eine vorgegebene Energiedichte erreicht wird. Wie erwähnt, ist die Pulsanstiegszeit 64 dabei kurz im Vergleich zur Pulsabfallzeit. Durch eine solche Art der Impulse wird erreicht, dass elektrische Durchschläge, die zu räumlichen und zeitlichen Störungen in der homogenen Plasmadichteverteilung führen würden, vermieden werden.In this case, the individual pulses 66, 67 have such a total amplitude that a predefined energy density is achieved beyond the predetermined direct voltage. As mentioned, the pulse rise time 64 is short compared to the pulse fall time. By such a kind of pulses is achieved that electrical breakdowns that would lead to spatial and temporal disturbances in the homogeneous plasma density distribution can be avoided.

FIG 4 bis FIG 9 zeigen Beispiele für Elektrodensysteme zur Erzeugung von Korona-Entladungen in vorzugsweise wässrigen Medien. In FIG 4 ist eine Platte-Platte-Anordnung von einer ersten Platte 70a als Elektrode und einer zweiten Platte 70b als Elektrode dargestellt. Die erste Platte 70a und die zweite Platte 70b sind parallel zu einander angeordnet. Die erste Platte 70a bildet die Hochspannungselektrode und ist über ein Hochspannungskabel mit dem Hochspannungsimpulsgenerator 46 verbunden. Die zweite Platte 70b bildet die Gegenelektrode und steht als geerdete Elektrode mit dem Hochspannungsimpulsgenerator 46 in Verbindung. 4 to FIG. 9 show examples of electrode systems for generating corona discharges in preferably aqueous media. In FIG. 4 is a plate-plate arrangement of one first plate 70a as an electrode and a second plate 70b as an electrode. The first plate 70a and the second plate 70b are arranged parallel to each other. The first plate 70a forms the high voltage electrode and is connected to the high voltage pulse generator 46 via a high voltage cable. The second plate 70b forms the counter electrode and is connected as a grounded electrode to the high voltage pulse generator 46 in connection.

Eine entsprechende Anordnung mit speziell ebenen Plattenelektroden ist in FIG 5 dargestellt. Es sind wiederum zwei massive Plattenelektroden 70a und 70c im festen Abstand vorhanden, wobei mittig eine Hochspannungselektrode 71 verläuft. Bei dieser Platte-Draht-Platte-Anordnung ist die Hochspannungselektrode 71 als massiver Draht ausgeführt und mit dem Hochspannungsausgang des Hochspannungsimpulsgenerators 46 verbunden. Die geerdeten Platten 70a, 70c stehen ebenfalls mit dem Hochspannungsimpulsgenerator in Verbindung.A corresponding arrangement with specially flat plate electrodes is in FIG. 5 shown. Again there are two solid plate electrodes 70a and 70c at a fixed distance with a high voltage electrode 71 in the middle. In this plate-wire plate assembly, the high voltage electrode 71 is made of a solid wire and connected to the high voltage output of the high voltage pulse generator 46. The grounded plates 70a, 70c are also in communication with the high voltage pulse generator.

FIG 6 zeigt eine Draht-Rohr-Anordnung als Elektrodensystem. In eine zylinderförmige Elektrode 72 ragt mittig eine Hochspannungselektrode 71 hinein. Wie in FIG 5 ist die Hochspannungselektrode 71 als massiver Draht ausgeführt und mit dem Hochspannungsimpulsgenerator 46 verbunden. Die zylinderförmige Elektrode 72, welche vorzugsweise als ein Drahtgeflecht ausgestaltet ist, ist geerdet und steht mit dem Hochspannungsimpulsgenerator 46 in Verbindung. FIG. 6 shows a wire-tube arrangement as an electrode system. A high-voltage electrode 71 projects centrally into a cylindrical electrode 72. As in FIG. 5 the high voltage electrode 71 is made as a solid wire and connected to the high voltage pulse generator 46. The cylindrical electrode 72, which is preferably configured as a wire mesh, is grounded and communicates with the high voltage pulse generator 46.

FIG 7 zeigt eine Spitze-Platte-Anordnung als Elektrodensystem. Drei Spitzen 73 sind über eine Hochspannungsleitung mit dem Hochspannungsimpulsgenerator 46 verbunden. Die Spitzen 73 sind rechtwinklig zu einer geerdeten Plattenelektrode 74 angeordnet. Der Abstand der Spitzenelektroden 73 zu der Plattenelektrode 74 ist einstellbar und kann somit für unterschiedliche Prozessbedingungen angepasst werden. FIG. 7 shows a tip-plate assembly as an electrode system. Three tips 73 are connected to the high voltage pulse generator 46 via a high voltage line. The tips 73 are arranged at right angles to a grounded plate electrode 74. The distance of the tip electrodes 73 to the plate electrode 74 is adjustable and thus can be adapted for different process conditions.

FIG 8 zeigt eine Elektrodensystemanordnung, welche 3 Platten 70a, 70d und 70e umfasst. Die erste Platte 70a, welche als Hochspannungselektrode mit dem Hochspannungsimpulsgenerator-46 verbunden ist, ist mittig zwischen zwei massiven Platten 70d und 70e angeordnet. Die Platten 70a und 70b sind über einen Plattenverbinder 70f verbunden. Da die Platte 70d als geerdete Gegenelektrode mit dem Hochspannungsimpulsgenerator 46 in Verbindung steht, hat die Platte 70e über dem Plattenverbinder 70f ebenfalls die Funktion einer geerdeten Gegenelektrode. FIG. 8 shows an electrode system assembly comprising 3 plates 70a, 70d and 70e. The first plate 70 a, which as High voltage electrode connected to the high voltage pulse generator -46 is centrally located between two solid plates 70d and 70e. The plates 70a and 70b are connected via a plate connector 70f. Since the plate 70d as a grounded counter electrode is in communication with the high voltage pulse generator 46, the plate 70e above the plate connector 70f also functions as a grounded counter electrode.

FIG 9 zeigt ein Elektrodensystem als Gitter-Gitter-Anordnung. Analog zur FIG 4 stehen sich hier ein erstes Gitter 75a und ein zweites Gitter 75b parallel gegenüber. Das erste Gitter 75a bildet hierbei die Hochspannungselektrode und ist mit dem Hochspannungsimpulsgenerator 46 verbunden. Das zweite Gitter 75b bildet die geerdete Gegenelektrode und steht mit dem Hochspannungsimpulsgenerator 46 in Verbindung. FIG. 9 shows an electrode system as a grid-grid arrangement. Analogous to FIG. 4 Here, a first grid 75a and a second grid 75b are parallel to each other. The first grid 75a forms the high voltage electrode and is connected to the high voltage pulse generator 46. The second grid 75b forms the grounded counter electrode and communicates with the high voltage pulse generator 46.

Eine hybride Entladung, wobei sich eine Elektrode 75a vollständig außerhalb einer zu behandelnden Faser-Suspension 39 befindet und eine zweite Elektrode 75b ganz oder teilweise in der Faser-Suspension 39 eingetaucht ist, wird mit einer alternativen Anordnung, bei welcher das Sieb als Elektrode 75a ausgestaltet ist erzeugt. Das Sieb ist als eine Gitterelektrode ausgeführt und bildet die Hochspannungselektrode, welche mit dem Hochspannungsimpulsgenerator 46 in Verbindung steht. Auch die geerdete Gegenelektrode 76b ist als eine Gitterelektrode ausgeführt und steht mit dem Hochspannungsimpulsgenerator 46 in Verbindung.A hybrid discharge wherein an electrode 75a is located entirely outside a fiber suspension 39 to be treated and a second electrode 75b is wholly or partially immersed in the fiber suspension 39 is provided with an alternative arrangement in which the screen is configured as electrode 75a is generated. The screen is designed as a grid electrode and forms the high voltage electrode which is connected to the high voltage pulse generator 46. Also, the grounded counter electrode 76 b is designed as a grid electrode and is in communication with the high voltage pulse generator 46.

In FIG 10 ist die aus FIG 1 bekannte schematische Pressenvorrichtung 11 vergrößert und detaillierter dargestellt. Das Papier 27 wird über zahlreiche Transportrollen und Walzen durch die Pressenvorrichtung 11 gerührt und dabei zunehmend entwässert und verdichtet. Auf die genaue Funktion und Arbeitsweise der Pressenvorrichtung wird nicht näher eingegangen, da dem Fachmann eine Pressenvorrichtung ohne die erfindungsgemäße Elektrodenanordnung bekannt ist. Unmittelbar nach einem Eingangsbereich für das Papier 27 in die Pressenvorrichtung sind die Elektroden 47 und 48, welche einen Plasmareaktor innerhalb der Pressenvorrichtung 11 bilden, angeordnet. Die Elektroden 47 und 48 sind mit dem Hochspannungsimpulsgenerator 46 verbunden. Mittels der Elektroden 47,48 und des Hochspannungsimpulsgenerators 46 wird wie zuvor bereits beschrieben zwischen den Elektroden 47,48 ein Plasma erzeugt. Die Papierbahn 27 verläuft zwischen den Elektroden 47,48 und wird so beidseitig mit Plasma behandelt. Zusätzlich bildet die Papierbahn 27 eine bereits beschriebene dielektrische Barriere und kann somit die Streamerbildung begünstigen.In FIG. 10 is that out FIG. 1 known schematic press apparatus 11 enlarged and shown in more detail. The paper 27 is agitated via numerous transport rollers and rollers by the press device 11 and thereby increasingly dewatered and compacted. On the exact function and operation of the press apparatus will not be discussed in more detail, since the person skilled in a press device without the electrode assembly according to the invention is known. Immediately after an entry area for the paper 27 in the press apparatus are the electrodes 47 and 48, which form a plasma reactor within the press device 11, are arranged. The electrodes 47 and 48 are connected to the high voltage pulse generator 46. By means of the electrodes 47, 48 and the high-voltage pulse generator 46, a plasma is generated between the electrodes 47, 48 as already described above. The paper web 27 extends between the electrodes 47,48 and is treated on both sides with plasma. In addition, the paper web 27 forms a dielectric barrier already described and can thus favor the streamer formation.

Ausgangsseitig ist ein weiteres Elektrodenpaar 12a und 47' angeordnet. Die Elektrode 12a ist dabei als eine Rollenelektrode ausgestaltet, ähnlich der Rollenelektrode in FIG 11. Das Papier 27 wird durch die Rollenelektrode 12a geführt. Über der Rollenelektrode 12a ist in einem Abstand von ca. 1 cm die Elektrode 47' angeordnet. Zwischen den Elektroden 47' und 12a wird mittels des mit ihnen verbundenen Hochspannungsgenerator 46 ein Plasma zur Behandlung des Papiers 27 erzeugt.On the output side, a further electrode pair 12a and 47 'is arranged. The electrode 12a is configured as a roller electrode, similar to the roller electrode in FIG FIG. 11 , The paper 27 is guided by the roller electrode 12a. About the roller electrode 12a, the electrode 47 'is arranged at a distance of about 1 cm. Between the electrodes 47 'and 12a, a plasma for the treatment of the paper 27 is generated by means of the high-voltage generator 46 connected to them.

Bei der Anordnung gemäß FIG 11 stellt die Transportrolle 12 die geerdete Gegenelektrode 12a dar. Kraft- und formschlüssig wird das Papier 27 durch die Transportrolle 12 geführt. An die Drähte 12b, 12b' bis 12bn (n=10) wird die Hochspannung angelegt. Eine ebenfalls geerdete Gegenelektrode 12c, welche halbkreisförmig den Verlauf der Transportrolle 12 folgt, ist in einer nicht dargestellten Art und Weise mit der Transportrolle 12, insbesondere mit der Rollenelektrode 12a, elektrisch verbunden. Es wird somit eine Elektrodenanordnung mit konstantem Abstand gebildet, in welcher mittig die einzelnen Drähte 12b bis 12bn angeordnet sind. Über die Transportrolle 12 somit über die geerdete Elektrode 12a läuft das zu bearbeitende Papier 27 und wird somit jeweils von den zwischen den beiden Elektroden 12a und 12c angeordnete Drähten 12b bis 12bn mit Plasma und/oder Gasentladungen beaufschlagt.In the arrangement according to FIG. 11 the transport roller 12 represents the grounded counterelectrode 12a. The paper 27 is guided by the transport roller 12 in a force-fit and form-locking manner. To the wires 12b, 12b 'to 12b n (n = 10) the high voltage is applied. A likewise grounded counter electrode 12c, which follows the course of the transport roller 12 in a semicircular manner, is electrically connected in a manner not shown to the transport roller 12, in particular to the roller electrode 12a. Thus, an electrode arrangement is formed with a constant spacing, in which the individual wires 12b to 12b n are arranged centrally. Via the transport roller 12, thus on the grounded electrode 12a, the paper to be processed runs 27 and is thus applied to each of the arranged between the two electrodes 12a and 12c wires 12b to 12b n with plasma and / or gas discharge.

Die Anordnung wird auch als gekrümmte Draht-Platte-Anordnung, welche einen Plasmareaktor bildet, bezeichnet.The arrangement is also referred to as a curved wire-plate arrangement which forms a plasma reactor.

Claims (43)

  1. Pressing device (11) for compressing paper and/or for extracting carrier liquid from moist paper (27), board or cardboard when paper (27), board or cardboard is being manufactured, wherein the pressing device (11) is arranged downstream of a screening device (9) and upstream of a drying system (13),
    characterised in that over, in or under a pressing area of the pressing device (11) at least one first electrode (47) is arranged which is connected to a high-voltage pulse generator (46), wherein a plasma can be produced in/on the moist paper (27), board or cardboard, or in the immediate vicinity thereof.
  2. Pressing device (11) according to claim 1,
    characterised in that a transport roller (12) is arranged as a first electrode.
  3. Pressing device (11) according to claim 1 or 2,
    characterised in that at least one second electrode (48) is provided for plasma production.
  4. Pressing device (11) according to one of claims 1 to 3,
    characterised in that at least one electrode is designed as a plate (70a, 70b).
  5. Pressing device (11) according to one of claims 1 to 4,
    characterised in that at least one electrode is designed as a wire (71).
  6. Pressing device (11) according to one of claims 1 to 5,
    characterised in that at least one electrode is designed as a wire mesh, in particular as a wire grid (75a, 75b).
  7. Pressing device (11) according to one of claims 1 to 6,
    characterised in that at least one electrode is designed as a grid (75a, 75b), in particular as an arrangement of rods and/or flat strips intersecting each other at right angles or obliquely.
  8. Pressing device (11) according to one of claims 1 to 7,
    characterised in that at least one electrode has one or more tips (73) .
  9. Pressing device (11) according to one of claims 1 to 8,
    characterised in that the electrodes are arranged as at least two opposed plates (70a, 70b), preferably running parallel to each other.
  10. Pressing device (11) according to one of claims 1 to 9,
    characterised in that the electrodes are arranged as at least two opposed grids (75a, 75b), preferably running parallel to each other.
  11. Pressing device (11) according to one of claims 1 to 10,
    characterised in that the electrodes are arranged such that a wire (71) or a grid (75a) is arranged as a second electrode between two plates (70d, 70e) which form the first electrode and are connected to each other via at least one plate connector (70f).
  12. Pressing device (11) according to one of claims 1 to 11,
    characterised by means (81) for introducing gas, in particular air or oxygen, preferably pure oxygen or oxygen with, for example, inert gas as the carrier gas, between or in the immediate vicinity of the electrodes (47, 48).
  13. Method for operating the pressing device according to the invention during compression of paper and/or extraction of carrier liquid from moist paper (27), board or cardboard when paper (27), board or cardboard is being manufactured, wherein the pressing device (11) is arranged downstream of a screening device (9) and upstream of a drying system (13),
    characterised in that the paper to be compressed is brought into contact with (preferably non-thermal) large-area plasma under atmospheric pressure, the plasma is produced in the immediate vicinity of the paper or in the paper, or a gas discharge, in particular a corona discharge, is produced under atmospheric pressure in the immediate vicinity of said paper.
  14. Method according to claim 13,
    characterised in that for the production of the plasma or of the gas discharge high-voltage pulses (66, 67) are produced between electrodes (43, 44) with a duration (62) of less than 10 µs.
  15. Method according to one of claims 13 or 14,
    characterised in that the process material is brought into contact with the plasma on both sides or is treated by means of the gas discharge.
  16. Method according to one of the preceding claims,
    characterised in that the plasma or the gas discharge is produced in the process material.
  17. Method according to one of the preceding claims,
    characterised in that the content of carrier liquid, in particular water, in the process material lies in the range between 2% and 85%, preferably in the range between 10% and 80% and in particular in the range between 10% and 70%.
  18. Method according to one of claims 13 to 17,
    characterised in that radicals (59) which act on the process material are produced in the plasma or by means of the gas discharge.
  19. Method according to claim 18,
    characterised in that for different types of process materials in a paper, cardboard or board manufacturing process, in particular at different process stages, radicals (59) of a different type or composition are used.
  20. Method according to claim 18 or 19,
    characterised in that the process material is exposed to radicals (59) of a different type or composition within a process step in a paper or cardboard manufacturing process, preferably in time sequentially.
  21. Method according to claim 19 or 20,
    characterised in that the process steps are selected from the following steps:
    - pressing,
    - drying,
    - smoothing,
    - winding,
    - unwinding,
    - bonding, especially before a coating,
    - finishing, coating, glazing or calendering,
    - preparation for printing, especially after calendering,
  22. Method according to one of claims 18 to 21,
    characterised in that ozone (O3), hydrogen peroxide (H2O2), OH, HO2 and/or HO2 - are produced as radicals (59).
  23. Method according to one of claims 18 to 22,
    characterised in that a production rate of radicals (59) and/or the composition of the radicals (59) produced is controlled by influencing the amplitude (U), pulse duration (62) and/or pulse repetition rate (63) of the high-voltage pulses (66, 67).
  24. Method according to claim 23,
    characterised in that a concentration of the radicals (59) produced is measured for control and regulation of the production rate and/or the type of radicals (59) produced.
  25. Method according to claim 23 or 24,
    characterised in that a property of the process material, preferably a quality property, in particular its opacity, gloss, whiteness, fluorescence or colour dot, is measured for control and regulation of the production rate or of the composition of the radicals (59) produced.
  26. Method according to one of claims 24 or 25,
    characterised in that the concentration or property is measured online.
  27. Method according to one of claims 23 to 26,
    characterised in that the amplitude (U) of the high-voltage pulses (66, 67) is changed at a constant repetition rate (63) for regulation.
  28. Method according to one of claims 23 to 27,
    characterised in that the repetition rate (63) of the high-voltage pulses (66, 67) is changed at a constant amplitude (U) for regulation.
  29. Method according to one of the preceding claims,
    characterised in that a high-voltage pulse duration (62) from 100 ns to 1 µs is used on the pressed sheet.
  30. Method according to one of the preceding claims,
    characterised in that oxygen and/or water vapour is supplied on the pressed sheet in the area to which plasma has been applied, with an increased partial pressure compared to atmospheric conditions.
  31. Method according to one of the preceding claims,
    characterised in that for the production of the plasma or of the corona discharge a DC voltage corona discharge is produced and the high-voltage pulses (66, 67) are superimposed on the DC voltage corona discharge.
  32. Method according to one of the preceding claims,
    characterised in that a pulse repetition rate (63) between 10 Hz and 5 kHz, or in particular 10 kHz, is used.
  33. Method according to one of the preceding claims,
    characterised in that the power injection of electrical energy into the plasma is primarily controlled by the regulation of the amplitude (U), pulse duration (62) and pulse repetition rate (63) of the superimposed high-voltage pulses.
  34. Method according to one of the preceding claims,
    characterised in that high-voltage pulses (66, 67) with a duration (62) of less than 3 µs, preferably of less than 1 µs, preferably of less than 500 ns, are used.
  35. Method according to one of the preceding claims,
    characterised in that high-voltage pulses (66, 67) with a duration (62) of more than 100 ns are used.
  36. Method according to one of the preceding claims,
    characterised in that a homogeneous, large-volume plasma with a high power density is produced, without there being plasma pinches or flashovers.
  37. Method according to one of the preceding claims,
    characterised in that a level of DC voltage is used such that a stable DC corona discharge is formed in the plasma only in conjunction with superimposed high-voltage pulses.
  38. Method according to one of the preceding claims,
    characterised in that the DC voltage used is lower than that for a stable operation without high-voltage pulse superimposition.
  39. Method according to one of the preceding claims,
    characterised in that the total amplitude used (DC voltage + pulse amplitude) is higher than the static breakdown voltage of the electrode arrangement.
  40. Method according to one of the preceding claims,
    characterised in that the total amplitude used corresponds to two to five times the static breakdown voltage of the electrode arrangement.
  41. Method according to one of the preceding claims,
    characterised in that the amplitude (U) of the high-voltage pulses is between 10% and 1000% of the DC voltage used.
  42. Method according to one of the preceding claims,
    characterised in that a gas flow is produced perpendicular to the electrode arrangement (43, 44).
  43. Method according to one of the preceding claims,
    characterised in that a gas flow is produced parallel to the electrode arrangement (43, 44).
EP06755311.5A 2005-06-16 2006-06-08 Pressing device for compressing paper and/or for extracting carrier liquid from paper and method therefor Not-in-force EP1891267B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE102005028023 2005-06-16
DE102005049290A DE102005049290A1 (en) 2005-06-16 2005-10-14 Pressing device for compacting paper and / or for removing carrier liquid from paper and method for this purpose
PCT/EP2006/063007 WO2006134062A1 (en) 2005-06-16 2006-06-08 Pressing device for compressing paper and/or for extracting carrier liquid from paper and method therefor

Publications (2)

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EP1891267A1 EP1891267A1 (en) 2008-02-27
EP1891267B1 true EP1891267B1 (en) 2014-03-19

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DE (1) DE102005049290A1 (en)
ES (1) ES2455519T3 (en)
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DE102011090121A1 (en) * 2011-12-29 2013-07-04 Siemens Aktiengesellschaft Change a formation of paper fibers in a paper web

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FI111475B (en) * 1997-09-24 2003-07-31 Metso Paper Inc Procedure and apparatus for checking fog and dust during manufacture and finishing of paper and paperboard
DE19836669A1 (en) * 1998-08-13 2000-02-24 Kuesters Eduard Maschf Preparation of the surface of a paper or cardboard web for calendering or printing comprises treating with an atmospheric plasma
SE513243C2 (en) * 1998-12-11 2000-08-07 Sca Research Ab A method for increasing the wet strength of a tissue material as well as the tissue material according to the method
EP1623072A1 (en) * 2003-05-13 2006-02-08 Università Degli Studi Di Milano - Bicocca Method for plasma treating paper and cardboards

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ES2455519T3 (en) 2014-04-15

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