WO2017060046A1 - Procédé et système de détermination de la contrainte hydraulique/mécanique exercée sur des bandes de cellulose - Google Patents

Procédé et système de détermination de la contrainte hydraulique/mécanique exercée sur des bandes de cellulose Download PDF

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Publication number
WO2017060046A1
WO2017060046A1 PCT/EP2016/071550 EP2016071550W WO2017060046A1 WO 2017060046 A1 WO2017060046 A1 WO 2017060046A1 EP 2016071550 W EP2016071550 W EP 2016071550W WO 2017060046 A1 WO2017060046 A1 WO 2017060046A1
Authority
WO
WIPO (PCT)
Prior art keywords
web
pulp
pulp web
unevenness
camera
Prior art date
Application number
PCT/EP2016/071550
Other languages
German (de)
English (en)
Inventor
Helmuth HARRER
Thomas Kefer
Christoph SPIELMANN
Original Assignee
Andritz Ag
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Andritz Ag filed Critical Andritz Ag
Publication of WO2017060046A1 publication Critical patent/WO2017060046A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/86—Investigating moving sheets
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F7/00—Other details of machines for making continuous webs of paper
    • D21F7/06—Indicating or regulating the thickness of the layer; Signal devices
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21G—CALENDERS; ACCESSORIES FOR PAPER-MAKING MACHINES
    • D21G9/00—Other accessories for paper-making machines
    • D21G9/0009—Paper-making control systems
    • D21G9/0036—Paper-making control systems controlling the press or drying section
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/30—Measuring arrangements characterised by the use of optical techniques for measuring roughness or irregularity of surfaces
    • G01B11/306—Measuring arrangements characterised by the use of optical techniques for measuring roughness or irregularity of surfaces for measuring evenness

Definitions

  • the invention relates to a method and a system for assessing the
  • Hydraulic / mechanical loading of a pulp web during production in a pulp drying plant consisting of a web formation part, a press part and a thermal drying plant, with the aim of predicting and avoiding web break.
  • Pulp is a raw material among other things for the paper industry and is produced on plants with up to several thousand tons per day. The investment volume for these plants can amount to several hundred million euros.
  • the production process is similar to papermaking. After recovering the pulp fibers in a cooking process, a pulp suspension is sprayed onto screens or transport felts. The pulp is now transported and dewatered along the machine at speeds of up to 300 m / min on the wire or between sieves and felts. During transport, the pulp continuously loses water. In the course of the wet part (forming and pressing zone) of the production machine, the pulp passes through several dewatering and
  • the pressing stages consist of roller pairs which form a gap through which the pulp is transported under high pressure.
  • Rollers are often used to improve drainage performance
  • Vacuum suction, radial bores and / or executed with grooves in the circumferential direction Vacuum suction, radial bores and / or executed with grooves in the circumferential direction.
  • the basic strength of a pulp web in terms of demolition and delamination is largely determined by the type of wood, fiber texture, basis weight, the
  • the pulp web In the dewatering elements, the pulp web is often loaded too high hydraulically and thereby destroyed. Above all, when passing through a press nip, the pulp web is subjected to adjustable line pressures which lead to a pressure gradient in the production direction and force the water out of the gap. With increasing production speed and increasing
  • Line pressure increases this pressure gradient on the inlet side of the gap and leads to ever greater flow velocities of the water and forces on the fibers within the pulp web.
  • Edge trimming eg due to wear of the water jet nozzles as well as through Air pockets due to intake air due to wear on seals. Both weakens the pulp web and leads to tears, in particular in the edge region and as a result of more frequent breaks in the pulp web.
  • the object of the invention is to detect the degree of unevenness or depth of the furrows, the unevenness of the edge trimming and the number of thin spots and in particular cracks in the edge area by measurement and the
  • the invention is characterized in that an optical system simultaneously detects a plurality of parameters and forms therefrom measurement variables which describe the state of the pulp web, in particular the degree of unevenness or the depths of furrows with regard to the strength of the pulp web.
  • a favorable development of the invention is characterized in that both parameters of the pulp web and the edge of the pulp web are detected simultaneously. This allows several influencing parameters to be recorded simultaneously with one measuring device.
  • An advantageous embodiment of the invention is characterized in that the measurement of the parameters by the optical system takes place after a press part before the thermal drying plant. This allows prompt reactions to changes in the railway structure.
  • a favorable embodiment of the invention is characterized in that the pulp web illuminated from the top and with a camera the
  • Intensity distribution of the translucent light is detected as transmitted light on the underside.
  • Intensity difference of the translucent light between light and dark areas is formed, and also for determining the intensity difference, the standard deviation of the intensity of the average over a certain area can be formed as a measure.
  • a favorable development of the invention is characterized in that additionally local peak values of the intensity are taken into account, the intensity preferably being normalized to the mean value before the brightness differences are calculated.
  • An advantageous embodiment of the invention is characterized in that one or more laser lines are projected onto the pulp web at a certain angle, wherein the deviation of the projected laser line or lines from the straight line determined by the camera is used as a measure of the unevenness of the pulp web.
  • a favorable embodiment of the invention is characterized in that the determination of the degree of unevenness is carried out in a time-sequential, traversing across the width of the pulp web.
  • the invention also relates to a system for the evaluation of
  • Hydraulic / mechanical loading of a pulp web during production in a pulp drying plant consisting of a web formation part is characterized in that an optical system consisting of a
  • Lighting device, a camera and a control system is provided, which is arranged after a press part in front of the thermal drying plant.
  • An advantageous development of the invention is characterized in that the illumination on the upper side and the camera are arranged on the underside of the pulp web. Thus, the camera can always work in the area that is not affected by the steam of the web.
  • a favorable embodiment of the invention is characterized in that in addition to the illumination device, a laser unit is provided.
  • An advantageous development of the invention is characterized in that a fork-shaped device is provided, wherein the pulp web runs between the two arms of the fork and advantageously the fork-shaped device in the vertical and horizontal directions can be moved.
  • the production speed can not reduce the influence of these process parameters
  • Parameters are determined on the unevenness of the pulp web (model).
  • a model-based controller first uses those parameters, taking into account the process engineering limits for the control, which do not reduce the production speed. So it is possible to build up a knowledge of experience and / or rules and to automatically categorize typical manifestations in the pictures.
  • the categories can either be defined as a rule or automatically formed by learning behavior. A combination is also conceivable.
  • the pulp web is due to the design obliquely upward 7 and after a deflection perpendicular 6 up to the dryer 3 out.
  • the vertical part 6 of the pulp web is dense on both sides
  • the top of the pulp web 18 is covered by dense vapor mist, which also does not allow optical inspection with sufficient accuracy.
  • the vapor rises in particular at the edges upwards and thus forms in the edge region a zone which is sufficiently free of condensing vapor to allow an optical inspection of the surface with the required resolutions ⁇ 0.2 mm.
  • the inspection of the weak points in the pulp web is carried out by
  • the invention describes a device in combination with a selected position on the plant which makes it possible under the described environmental conditions to determine the above-described weak spots of the pulp web in operation in comparable quality as in the laboratory.
  • the camera 17 is at the edge, below the pulp web at an angle
  • the image section is selected so that the web edge 15 can be seen and its position in the image can be measured.
  • the edge 15 differs by a dark brightness value from the very bright area outside the pulp web.
  • the deviation of the edge line 15 from the straight line shows the quality of the
  • Edge trimming with small deviations corresponding to a clean cut On the underside of the pulp web, one or more laser lines 14 are projected onto the pulp web.
  • the laser 20 is mounted at a certain angle to the camera 17, so that the deviation of the line from the straight line
  • the position of the pulp web changes operationally in the vertical direction as well as in the horizontal direction. To compensate for these movements is the
  • the vertical adjustability ensures that the camera and the laser are always in focus and that the illumination intensity remains constant due to the constant distance to the pulp web.
  • the horizontal adjustability ensures that the web edge is always visible and the average brightness changes due to unequal coverage.
  • Fig. 4 is a camera image of a pulp web with edge region
  • Fig. 5 represent an inventive arrangement for determining the unevennesses in the transmitted light.
  • Fig. 1 shows the scheme of a Zellstofftrockêtsanange, in which a
  • Pulp suspension is fed via a headbox onto a sieve 4. It can be a fourdrinier with or without Top Former, as shown, but also a twin wire, in which the pulp suspension between two screens in a first wedge-shaped dewatering zone is abandoned. In the wet part 1 then follow several pressing stages 2, which as shown may have a common felt 4 or as separate presses with separate felts for each
  • Fig. 2 shows the different unevenness viewed with a transmitted light method, i. Lighting unit and camera are arranged on different sides of the pulp web. Depending on the composition and the
  • Fig. 3 shows this situation when using a line laser.
  • one (shown here) or several laser lines are projected onto the pulp web with a suitable optical system.
  • the deviation from the straight line is then a measure of the unevenness of the pulp web. It can be seen here with a smooth surface 11 practically a straight line, at beginning irregularities 12 a slightly wavy line and deep grooves 13 a jagged line.
  • the standard deviation or a rating of the peak values can be used as a measure of the deviation from the straight line.
  • Fig. 4 shows a camera image of the pulp web with the detection of the edge region.
  • 3 laser lines 14 are shown, with which the surface texture at several positions of the pulp web can be measured simultaneously.
  • the smoothness of the web edge 15 is used here as a parameter, with the lighter surface representing the lighting unit directly.
  • Partial air pockets (blistering) 16 are also present in the marginal area. 16. Extremely irregular edges 15 as well as air pockets 16 can lead to unexpected tears and thus
  • FIG. 5 shows the arrangement of a system for assessing the hydraulic / mechanical load of a pulp web during production
  • a lighting device 19 is arranged above the pulp web 18.
  • a camera 17 which detects the intensity distribution of the penetrating light. The difference in intensity between light and dark areas then forms a parameter for the unevenness of the pulp web 18. Based on this measured variable and corresponding limit values, a control of the system can then take place in such a way that breaks or delamination of the pulp web are avoided.
  • a variant of the determination of the unevenness of the web is shown by means of laser 20. For this purpose, one or more lines are projected by means of a suitable optics at a certain angle to the pulp web 18.
  • Deviation of the projected line from the straight line is then a measure of the
  • this measurement is combined with a measurement by means of transmitted light method.
  • the laser 20 further serves to determine the exact position of the measuring device 23 in relation to the pulp web 18 and optionally, the position is corrected starting from the measuring signal such that the distances provided are optimally adjusted both in height and transverse to the web running direction. For adjusting the distance of the
  • Measuring device 23 is a motor 21 and to adapt to the position transverse to the web running direction, a motor 22 is provided.
  • the invention is not limited by the illustrated examples. Thus, e.g. Also, several cameras arranged side by side can be installed or the camera traversing over the web width can be provided.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Polysaccharides And Polysaccharide Derivatives (AREA)
  • Paper (AREA)

Abstract

L'invention concerne un procédé permettant de déterminer la contrainte hydraulique/mécanique exercée sur une bande de cellulose pendant la production. Le procédé est principalement caractérisé en ce qu'un système optique forme une grandeur de mesure qui décrit le degré d'irrégularité ou la profondeur des stries dans la bande de cellulose. L'invention concerne également un système permettant la mise en œuvre du procédé, comprenant un système optique composé d'un dispositif d'éclairage (19), d'une caméra (17) et d'un système de régulation. Le procédé ou le système selon l'invention permettent de détecter précocement les causes de déchirures ou de délaminations de bandes de cellulose et de prendre des mesures appropriées pour éviter les déchirures ou les délaminations.
PCT/EP2016/071550 2015-10-05 2016-09-13 Procédé et système de détermination de la contrainte hydraulique/mécanique exercée sur des bandes de cellulose WO2017060046A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AT508472015 2015-10-05
ATA50847/2015 2015-10-05

Publications (1)

Publication Number Publication Date
WO2017060046A1 true WO2017060046A1 (fr) 2017-04-13

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Family Applications (1)

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PCT/EP2016/071550 WO2017060046A1 (fr) 2015-10-05 2016-09-13 Procédé et système de détermination de la contrainte hydraulique/mécanique exercée sur des bandes de cellulose

Country Status (2)

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UY (1) UY36933A (fr)
WO (1) WO2017060046A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2021124250A1 (fr) * 2019-12-20 2021-06-24 Stora Enso Oyj Procédé d'identification de défauts dans un film, procédé et dispositif de fabrication d'un film
WO2021124251A1 (fr) * 2019-12-20 2021-06-24 Stora Enso Oyj Procédé de détermination de l'épaisseur d'un film, procédé et dispositif de fabrication d'un film
DE102021131557A1 (de) 2021-12-01 2023-02-23 Voith Patent Gmbh Verfahren zur Erkennung eines Bahnlauffehlers einer in einer Faserstoffbahn-Herstellungsmaschine bewegten Faserstoffbahn, Verfahren zur Regelung einer Faserstoffbahn-Herstellungsmaschine sowie zugehöriges System und zugehörige Maschine

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5696591A (en) * 1996-01-05 1997-12-09 Eastman Kodak Company Apparatus and method for detecting longitudinally oriented flaws in a moving web
US6236429B1 (en) * 1998-01-23 2001-05-22 Webview, Inc. Visualization system and method for a web inspection assembly
US20060070417A1 (en) * 2004-07-16 2006-04-06 John Nieminen Flatness monitor
WO2008034954A2 (fr) * 2006-09-22 2008-03-27 Metso Paper, Inc. Procédé et dispositif de mesure des propriétés d'une toile en mouvement
WO2009149481A1 (fr) * 2008-06-11 2009-12-17 Andritz Ag Dispositif et procédé d'essorage d'une bande de matériau fibreux

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5696591A (en) * 1996-01-05 1997-12-09 Eastman Kodak Company Apparatus and method for detecting longitudinally oriented flaws in a moving web
US6236429B1 (en) * 1998-01-23 2001-05-22 Webview, Inc. Visualization system and method for a web inspection assembly
US20060070417A1 (en) * 2004-07-16 2006-04-06 John Nieminen Flatness monitor
WO2008034954A2 (fr) * 2006-09-22 2008-03-27 Metso Paper, Inc. Procédé et dispositif de mesure des propriétés d'une toile en mouvement
WO2009149481A1 (fr) * 2008-06-11 2009-12-17 Andritz Ag Dispositif et procédé d'essorage d'une bande de matériau fibreux

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2021124250A1 (fr) * 2019-12-20 2021-06-24 Stora Enso Oyj Procédé d'identification de défauts dans un film, procédé et dispositif de fabrication d'un film
WO2021124251A1 (fr) * 2019-12-20 2021-06-24 Stora Enso Oyj Procédé de détermination de l'épaisseur d'un film, procédé et dispositif de fabrication d'un film
DE102021131557A1 (de) 2021-12-01 2023-02-23 Voith Patent Gmbh Verfahren zur Erkennung eines Bahnlauffehlers einer in einer Faserstoffbahn-Herstellungsmaschine bewegten Faserstoffbahn, Verfahren zur Regelung einer Faserstoffbahn-Herstellungsmaschine sowie zugehöriges System und zugehörige Maschine

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Publication number Publication date
UY36933A (es) 2017-05-31

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