EP2227593A1 - Système et procédé pour réguler au moins un paramètre de qualité d'une bande de matériau, en particulier d'une bande de matière fibreuse dans une machine à papier et/ou à carton - Google Patents

Système et procédé pour réguler au moins un paramètre de qualité d'une bande de matériau, en particulier d'une bande de matière fibreuse dans une machine à papier et/ou à carton

Info

Publication number
EP2227593A1
EP2227593A1 EP08805176A EP08805176A EP2227593A1 EP 2227593 A1 EP2227593 A1 EP 2227593A1 EP 08805176 A EP08805176 A EP 08805176A EP 08805176 A EP08805176 A EP 08805176A EP 2227593 A1 EP2227593 A1 EP 2227593A1
Authority
EP
European Patent Office
Prior art keywords
control system
control
quality
water weight
paper
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP08805176A
Other languages
German (de)
English (en)
Inventor
Jörg Spindler
Niels Hardt
Oliver Kaufmann
Jens Haag
Hartmut Abel
Armin Bauer
Rudolf Münch
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Voith Patent GmbH
Original Assignee
Voith Patent GmbH
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 Voith Patent GmbH filed Critical Voith Patent GmbH
Publication of EP2227593A1 publication Critical patent/EP2227593A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • 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
    • D21G9/0027—Paper-making control systems controlling the forming section
    • 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
    • D21G9/0045—Paper-making control systems controlling the calendering or finishing

Definitions

  • the invention relates to a system for controlling at least one quality parameter of a material web, in particular a fibrous web in a paper and / or paperboard machine, and a method for this purpose.
  • the properties of the web must be continuously monitored and controlled to ensure adequate end product quality and to minimize the amount of discarded end product.
  • different variables can be used, for example the weight per unit area, the water weight or the thickness of a paper web at different points in the production process.
  • the MD direction refers to the so-called machine direction, which essentially coincides with the direction that the material web passes during the production process.
  • the term CD direction stands for the direction along the width of the web. The CD direction, which is to the machine direction and stands on this substantially perpendicular.
  • the processes on the screen significantly affect the final quality of the paper, for example the formation and strength of the paper.
  • the factors that affect paper quality are the ratio of the speed of the screen to the applied fabric, and the angle at which the fabric strikes the screen and the degree at which it drains from the web.
  • the difference between the speed of the fabric jet and the screen affects the mean orientation of the fibers of the paper, the mean orientation of the fibers in turn being critical to both the paper formation and the sheeting.
  • the Otro basis weight is the so-called oven-dry basis weight of the paper; Otro stands for a measure of the degree of dryness of the paper after drying under specified conditions. Also defined is the Lutro basis weight, which refers to the basis weight including the moisture of the produced web.
  • air- ckenem paper is a moisture content greater than O percent and a normal moisture content that is basically necessary for the paper. For wood pulp pulp, the proportion is 90 parts air to 10 parts water.
  • the quality measurements can be measured, for example, at the end of the paper machine, for example by optical methods as described in US Pat. No. 4,786,817, US Pat. No. 5,073,712 or EP 0 390 623 A1.
  • the disadvantage of the quality measurement at the end of the paper machine is that the transport dead time of the actuators, which are, for example, the headbox in the wet end of the machine, is relatively large to the end of the paper machine.
  • the duration of the transport time is about 1 minute from the wet end of the paper machine, that is from the headbox to the end.
  • a dead time of one minute means that disturbances of the quality with wavelengths less than 8 times the dead time, ie 8 minutes, are not controllable.
  • WO 99/55959 A1, EP 1 021 729 B1 or WO 99/64963 A1 proposes the use of sensors for measuring the conductivity of the substance on the Screen in the wet end of the paper machine.
  • Such measuring devices can be arranged very close to the actuators in the wet part, for example on the actuators of the fabric on the outside.
  • a disadvantage of such sensors, however, is that the conductivity is a measure of the moisture of the web and not for their area-related mass.
  • WO 99/55954 A1 and WO 99/64963 A1 propose a multiplicity of so-called sensors which, based on the conductivity, make measurements of the moisture content, either in the machine direction (MD direction ) or in the cross machine direction (CD direction).
  • MD direction machine direction
  • CD direction cross machine direction
  • WO 99/64963 A1 proposes a multiplicity of so-called sensors which, based on the conductivity, make measurements of the moisture content, either in the machine direction (MD direction ) or in the cross machine direction (CD direction).
  • MD direction machine direction
  • CD direction cross machine direction
  • This optimal water profile can then be adapted with different functions, that is to be fitted. Then, when the production is driven, the characteristic that has led to the optimal paper is constantly readjusted.
  • a regulation does not take into account the correlation between a water weight profile and the wet weight profile. Rather, it has been found that this correlation is constantly changing and therefore has the method for producing optimal fiber webs shown in WO 99/64963 A1 disadvantages.
  • the object of the invention is thus a system for controlling the quality parameters of a material web, in particular a fibrous web in a paper and / or board machine and such a method.
  • the object is achieved in that in a system for controlling at least one quality parameter of a material web, in particular a fibrous web in a paper and / or board machine, a first control system is provided which determines the water weight profile along a machine direction (MD direction) and / or in a cross machine direction (CD direction) of a paper machine.
  • This control system is supplemented according to the invention by at least one second control system, wherein the second control system regulates one or more quality parameters of a material web.
  • the control system for recording water weight profile along a machine direction (MD direction) or in the cross machine direction (CD direction) of a paper machine may comprise a multiplicity of water weight sensors below or adjacent to the screen which receive a conductivity signal, ie a suitable signal correlated with the water weight as described for example in WO 99/55959 A1 for the CD direction or as described in WO 99/64963 A1 for the MD direction.
  • Suitable sensors use, for example, the conductivity of the medium, the dielectric constant of the medium or the infrared absorption of the medium.
  • sensors for example, are Switzerland, optical sensors or conductivity sensors into consideration.
  • other measurement principles are also conceivable, for example based on absorption / reflection / delay of the sound, ultrasound, visible light.
  • the second control system which regulates the quality parameter (s) of the material web, can be, for example, a control system that has sensors for determining the basis weight of the Otro basis weight or the Lutro basis weight and the formation and / or the thickness.
  • Sensors which measure such properties of a paper web are, for example, sensors on an optical basis, as described in EP 0 972 882 A1.
  • the system for controlling at least one quality parameter can be configured such that the first control system that regulates the water weight profile along a machine direction and / or in a cross-machine direction of a paper machine, the second control system for controlling the quality parameter of a material web in the sense is subordinate to a Kaskadenregiung.
  • the output of the second control system, the quality parameter or the quality parameters of a material web is used as a soli value for the first control system, which is used for the water weight profiling control.
  • the Wasserissprofii-regulation itself comprises at least one sensor for absorbing the water weight, as described for example in WO 99/55959 A1.
  • actuators for the Water weight control is for example the dilution water valves on a headbox, the apertures of the Stoffaufiaufs, the forming divisions on vacuum, inguinal pressure, inguinal angle, the amount of dilution water in the headbox and the addition of chemical additives that are effective on the Reten- tion on the basis weight in question.
  • the two control systems are not connected in series in the form of a cascade are constructed parallel to each other, wherein preferably the second control system is superimposed on the first control system and the second control system for controlling the quality parameters has an output via which quantities the first control system can be supplied.
  • Quantities of the water weight travel circle could also be made available to the quality control loop, ideally in the sense of a feed forward structure.
  • the output variables of the second control system relating to the quality parameters of the material web could be forwarded to the first control system of the water weight profile control.
  • the output variables of the first control system could be transmitted to the water weight profile control, not as nominal values, but rather in the range of the recorded signals and thus in the setpoint formation for the water weight control.
  • output variables of the water weight profile control to the quality control, that is second regulatory system, as a direct repercussion on the quality control.
  • a temporal slow change may be due to the requirements of other paper grades that are to be kept constant at the same time
  • the advantage in any case is that the first control system ensures a constant quality and the second control system offers a further degree of freedom for process optimization via the water weight standard setpoint.
  • the second control system with which the quality parameters of the material web are regulated, preferably serves to calm the rapid fluctuations which occur in the water weight profile and can influence the quality of the material web. This can be done by splitting the control signal of the water profile into a high and low frequency component. Since only the rapid variations in the water weight profile are to be compensated by means of the quality control, it is preferred for the quota control, ie the dual control system, to regulate only the high-frequency portion of the water profile.
  • the invention also provides a method for controlling at least one quality parameter.
  • the method according to the invention for controlling at least one quality parameter at least the water weight profile in the MD direction and / or CD direction is controlled with a first control system and a quality parameter of the material web with a second control system.
  • control system is constructed as a kind of cascade control
  • at least one size of the first control system is transmitted to the second control system, for example as a desired value for the inner control loop, which represents, for example, the control loop for the water weight profile.
  • a quality parameter of the second control system such as the basis weight, the Otro basis weight, the Lutro basis weight, the formation or the thickness, to be transmitted to the first control loop as the water weight target value.
  • tracking would no longer be necessary, as in the prior art, since a changing correlation is detected by the quality control loop and immediately converted into a setpoint value for a multi-variable controller for water weight profile control.
  • the two control loops are constructed independently, but sizes of the quality control system, that is, the second control system are supplied to the first control system, for example, control values for the headbox, as resulting from the Quality control loop regulation provided to water weight professional.
  • the water weight profile value of the first control system can be set to be either constant or slow in time.
  • slowly changing it is meant that the quality regulator only uses the means to change the water weight setpoint in exceptional cases.
  • a formation controller may use the headbox panel as the actuator - but if the panel has already reached a boundary, the water weight penalty will be changed.
  • the water weight setpoint can be determined automatically both manually and using process information. If the control is a multivariable control, it is possible with such a control to take into account further parameters, such as the formation.
  • control method can always be performed so that the paper machine speed is used as a reference size for the water weight profile and the water weight profile does not change or only insignificantly when changing the paper machine speed.
  • water weight profile changes in response to the change in paper machine speed.
  • monitoring steps may also be incorporated in the control method, such as monitoring stalking activities of the actuators to provide the water weight profile which may be used to indicate that the screen, vacuum, moldings or other drainage elements are not functioning properly or paper properties or raw materials are not in order.
  • Such monitoring can be made more precise with the aid of empirical values and previous knowledge, formulated in rules or a theorem and then automatically diagnosed or monitored be used. For example, it is notable for the operator of the machine if significantly higher (lower) activities are necessary to achieve a given water weight. This indicates that, for example, the machine, the clothing or the stele organs (for example, vacuum generation and valves) have changed unexpectedly. But if a vacuum generation and possibly other issues can be excluded, the effect is due to a change in the feedstock. For a more accurate automatic diagnosis, however, additional information is required such as - type, age, wear condition of the clothing;
  • the water weight profile In general, in the water weight profile, actuating activities of, for example, cross-profile devices, that is to say in the CD direction, are visible much earlier than on the finished paper web. Therefore, the water weight profile is not only suitable for regulation, but therefore the water weight cross profile is not only suitable for control but also for diagnosing the effectiveness of steep movements.
  • the water weight cross profile shows a surprisingly large / small change, it means that the process behavior does not match the expectation. A targeted optimal regulation is thus no longer possible. The operator then has to analyze / correct the overall system in order to get an optimal control again.
  • Figure 1 shows the basic structure of a paper machine
  • FIG. 2 shows a first embodiment of a control according to the invention
  • FIG. 3 shows a second embodiment of a control according to the invention.
  • FIG. 1 shows a basic structure of a paper machine.
  • the pulp or pulp suspension is applied by means of a headbox 10 to a wet end 20 comprising a peripheral sieve 22.
  • water weight sensors 25 are arranged in the area of the wet end 20 below the sieve 22. These can be arranged both in the machine direction 30 (M D direction) and in the cross machine direction 40 (CD direction). With the help of the water weight sensors 25 it is possible to analyze the water weight profile. For this purpose, these measured values are fed to a professional analyzer or profile regulator 100, which in turn is part of the first control system with which the water weight profile is regulated on the basis of predetermined solitary sizes.
  • the first control system represents, for example, dilution water vents (not shown) on the headbox 10 as actuators.
  • the wet end 20 of the paper machine is followed by a press section 50 and the treatment machine 60, with which the paper web is further dehydrated.
  • the processing machine 60 may comprise, for example, the dryer section, coater or calender with which the drying process can be completed.
  • an optical sensor for example a quality sensor 110, for example a CCD camera, radio-metric sensors, optical sensors or microwave sensors can be arranged, with which the formation of the sheet, which in turn is a quality feature of the dry paper web, is detected and to a second control system 120 that handles the quality control 120.
  • Quality sensors are usually arranged after the dryer section, but other installation locations are conceivable. So it is conceivable to determine the paper property "formation" before the press in the former area.
  • the quality control 120 in turn also uses as Actuators the actuators headbox 10.
  • Actuators the actuators headbox 10.
  • a cascade control system is realized.
  • a setpoint value of quality is first of all created, which results from the desired paper quality.
  • the output signal of the quality control is transmitted to the first control system 100, in the present case the water weight profile control.
  • the output value of the quality control is then the setpoint for the water weight profile control.
  • the Wasserpersprofii is regulated.
  • the regulation of the water weight profile is carried out by means of actuators, for example on the headbox 10 (not shown).
  • the reference numeral 50 designates the press section and the reference numeral 60 the processing machine comprising, for example, the dryer section.
  • quality sensors 110 for example a CCD camera, radiometric sensors, optical sensors or microwave sensors, are arranged at the end of the paper machine, for example sensors on an optical basis, which sense the paper quality and are fed to the first control system. If, for example, a loss of quality is sensed at the end of the paper machine, then the setpoint in the cascade control is changed in the downstream water weight profile control.
  • the quality sensors can be arranged at the very end of the press section 50 and / or the processing machine 60, as shown by line 140 or also within the press section 50 or processing machine 60, as indicated by the dotted line 130 for the return to the quality controller 120.
  • FIG. 3 shows an alternative construction of a control according to the invention.
  • a first control system which provides water weight profile control
  • a second control system 220 which is independent of the first water weight profile control system and controls paper quality.
  • the set point 202 of the first control system 200 concerning the water weight profile control is set independently of the second control system 220 which controls the paper quality.
  • This setpoint 202 may either be a constant or change slowly. Even a manual setting would be possible.
  • the coupling between the second paper quality control system 220 and the first water weight profile control system 200 takes place at output 206 of the paper quality control, prior to actuation of the actuators, for example at the headbox 208, for example at the headbox itself or in the headbox feed process the Textilquaiticiansregelung is communicated to the Wasserissregelung 200, before the wet weight of the paper machine determined water weight profile is returned as a controlled variable 210 in the first control system 200.
  • This allows the Wasserissregeiung the time given to a change in the control outputs 206 preventively and synchronously to react, for example, to avoid a water weight change, although the control output 206 itself changes.
  • the actuators are, for example, valves or pumps or diaphragms with the aim of changing the mass flow in the MD direction or locally in the CD direction.
  • the sensed signals 212 may be transmitted to the quality control system before the paperquality is returned to the input 214 by means of, for example, formation sensors 110 in the second control system 220.
  • further aggregates of the paper machine may be provided, such as a take-up device 216.
  • a paper quality control is specified for the first time, which can intervene faster than previously in the regulation of paper quality.
  • the paper quality control system it is possible with the paper quality control system to regulate a quality profile of the paper web while at the same time compensating for rapid fluctuations in the water weight profile control.
  • First control system water weight profiling control

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Abstract

L'invention concerne un système pour réguler au moins un paramètre de qualité d'une bande de matériau, en particulier d'une bande de matière fibreuse dans une machine à papier et/ou à carton, comprenant : au moins un premier système de régulation (100, 200) pour réguler un profil de poids d'eau dans le sens machine (direction MD) et/ou transversalement au sens machine (direction CD) d'une machine à papier; et au moins un deuxième système de régulation (120, 220), le deuxième système de régulation (120, 220) régulant le paramètre de qualité de la bande de matériau.
EP08805176A 2007-12-17 2008-10-09 Système et procédé pour réguler au moins un paramètre de qualité d'une bande de matériau, en particulier d'une bande de matière fibreuse dans une machine à papier et/ou à carton Withdrawn EP2227593A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102007055833A DE102007055833A1 (de) 2007-12-17 2007-12-17 System und Verfahren zur Regelung wenigstens eines Qualitätsparameters einer Materialbahn, insbesondere einer Faserstoffbahn in einer Papier- und/oder Kartonmaschine
PCT/EP2008/063529 WO2009077219A1 (fr) 2007-12-17 2008-10-09 Système et procédé pour réguler au moins un paramètre de qualité d'une bande de matériau, en particulier d'une bande de matière fibreuse dans une machine à papier et/ou à carton

Publications (1)

Publication Number Publication Date
EP2227593A1 true EP2227593A1 (fr) 2010-09-15

Family

ID=40149626

Family Applications (1)

Application Number Title Priority Date Filing Date
EP08805176A Withdrawn EP2227593A1 (fr) 2007-12-17 2008-10-09 Système et procédé pour réguler au moins un paramètre de qualité d'une bande de matériau, en particulier d'une bande de matière fibreuse dans une machine à papier et/ou à carton

Country Status (3)

Country Link
EP (1) EP2227593A1 (fr)
DE (1) DE102007055833A1 (fr)
WO (1) WO2009077219A1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102010041052A1 (de) * 2010-09-20 2012-03-22 Voith Patent Gmbh Verfahren zum Regeln der Formation einer Faserstoffbahn
DE102012211656A1 (de) * 2012-07-04 2014-01-09 Voith Patent Gmbh Verfahren zur Verbesserung von Qualitätseigenschaften einer Faserstoffbahn
US20150292158A1 (en) * 2012-09-28 2015-10-15 Voith Patent Gmbh Method for controlling the formation of a fiber web of a fiber or paper producing process

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4786817A (en) 1986-08-29 1988-11-22 Measurex Corporation System and method for measurement of traveling webs
US5019710A (en) 1989-03-30 1991-05-28 Measurex Corporation Optical system for detecting properties of traveling sheet materials
US5073712A (en) 1991-04-11 1991-12-17 Abb Process Automation, Inc. Light scanner web profile measurement apparatus and method
US5944955A (en) * 1998-01-15 1999-08-31 Honeywell-Measurex Corporation Fast basis weight control for papermaking machine
US6092003A (en) 1998-01-26 2000-07-18 Honeywell-Measurex Corporation Paper stock shear and formation control
US6168687B1 (en) 1998-04-24 2001-01-02 Honeywell-Measurex Corporation System and method for sheet measurement and control in papermaking machine
US6086716A (en) 1998-05-11 2000-07-11 Honeywell-Measurex Corporation Wet end control for papermaking machine
DE19831612A1 (de) 1998-07-14 2000-01-20 Voith Sulzer Papiermasch Gmbh Meßsystem

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2009077219A1 *

Also Published As

Publication number Publication date
WO2009077219A1 (fr) 2009-06-25
DE102007055833A1 (de) 2009-06-18

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