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WO2005078189A2 - Procede et systeme de commande permettant de regler l'epaisseur d'une bande continue de matiere fibreuse dans le sens machine - Google Patents

Procede et systeme de commande permettant de regler l'epaisseur d'une bande continue de matiere fibreuse dans le sens machine Download PDF

Info

Publication number
WO2005078189A2
WO2005078189A2 PCT/FI2005/000079 FI2005000079W WO2005078189A2 WO 2005078189 A2 WO2005078189 A2 WO 2005078189A2 FI 2005000079 W FI2005000079 W FI 2005000079W WO 2005078189 A2 WO2005078189 A2 WO 2005078189A2
Authority
WO
WIPO (PCT)
Prior art keywords
thickness
model
fibre web
calender
nip
Prior art date
Application number
PCT/FI2005/000079
Other languages
English (en)
Other versions
WO2005078189A3 (fr
Inventor
Tapio MÄENPÄÄ
Original Assignee
Metso Paper, Inc.
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 Metso Paper, Inc. filed Critical Metso Paper, Inc.
Publication of WO2005078189A2 publication Critical patent/WO2005078189A2/fr
Publication of WO2005078189A3 publication Critical patent/WO2005078189A3/fr

Links

Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21G—CALENDERS; ACCESSORIES FOR PAPER-MAKING MACHINES
    • D21G1/00—Calenders; Smoothing apparatus
    • 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
    • D21G1/00—Calenders; Smoothing apparatus
    • D21G1/002—Opening or closing mechanisms; Regulating the pressure
    • D21G1/004—Regulating the pressure
    • D21G1/0046—Regulating the pressure depending on the measured properties of the calendered web

Definitions

  • the present invention concerns a fibre web machines.
  • the present invention in more detail relates to a control method and a control system to be utilized for adjusting thickness of paper or of similar web material when the web to be calendered goes through a set of rollers of a calender of the fibre web machine, which set of rollers comprises one or more roller nips.
  • the method according to the present invention covers both controls required by normal production situations and controls in the situations, whereby there is taking place transition to a production state or vice versa.
  • the normal production situation refers to a mode, in which case a machine speed does not meet essential changes or the changes in the machine speed do not affect quality.
  • the change situations of the machine speed and machine up-run / machine shut-down represent situations, in which case it is moved to the production mode, out of the production mode or change modes and transition modes of the production state.
  • the calendering is in principal a simple processing phase of the fibre web.
  • the web is repeatedly pressed in the calender by rollers that pressed against each other and form there between a roller nip/-s so that the web will become thinner and more even.
  • Problematic is however, to anticipate, how much thimier and more even the a web may become as the consequence of the processing like this, because the result of the processing is dependent on very many variables and properties of the web itself.
  • the publication 151 describes a method of the smallest square metre sum or the Kalman filter to formulate a model describing a thickness change of paper such that the model will be linear in regard to unknown parameters.
  • the goal is to eliminate or to reduce at least essentially weaknesses and uncertainties that are related to the traditional calendering process.
  • the goal is to accomplish a new and ingenious method for adjusting thickness of the fibre web in the machine direct.
  • the goal is to accomplish a new and ingenious system to adjust thickness of the fibre web in the machine direct.
  • it is striven for an exact total control of the thickness of the fibre web, advantageously paper, in the machine direct in all production situations and/or when it is switched to the production state from the up-run state on the calender or vice versa.
  • the goal is to adjust the thickness of the paper wanted using nip-specific controls.
  • a prognosis value of thickness which is achieved by the model, is verified at least by a value of a thickness measuring after the roller nip or the calender in order to certify correctness thereof. Then it is also further advantageous that the prognosis value is verified by a value of a thickness measuring preceding the calender or by a laboratory definition of thickness.
  • the compressibility model of the fibre web is used in a chaining manner for describing a total process of a calender.
  • the method is adapted both in a normal production state and in connection with the changes in the machine speed. It is also specific to the present control and adjusting method according to the invention, that the parameters of the mathematical model equation are updated on a type basis and on an operation point basis by an on-line algorithm and that the updated parameters are recorded in the type-specific tables.
  • the adjustment is carried out as an anticipating adjustment, which is based on the model.
  • the control system when the web to be calendered goes through a set of rollers of a calender of a fibre web machine, which contains one or more roller nips, that in the calculation of the set values of the line load of the roller nip and the surface temperatures of chill roller the system adapts the compression model of the fibre web to control and adjusting the compressibility.
  • control system verifies the prognosis value of the thickness, which has been received with the model, to secure its validity, by at least the value of the thickness measuring subsequent to a roller nip or to a calender.
  • control system verifies the prognosis value with the value of the laboratory definition of a thickness or with the value of the thickness measuring, which precedes the roller nip or the calender.
  • the system adapts the compression model of the fibre web in a chaining manner for the control and for the adjustment of the roller nips in order to control and adjust the total process of the calender.
  • the system is a control system both for the normal production state and for the state of change of the machine speed. It is specific to the present control system according to the invention also an online algorithm, which updates the parameters of the mathematical model equation on a type basis and on an operation point basis, and that the updated parameters are recorded in the type-specific tables.
  • the novelty and the inventiveness relate to the used way of approach to form in the roller nip the mathematical model, which is utilised, when there are calculated nip-specifically controls to the line loads and to the surface temperatures of chill roller to be warmed.
  • the method is applicable both to calenders having one, two or more roller nips and to multi-roller calenders.
  • the compression model of the fibre web determines thickness changes, which take place in each roller nip, and by connecting the thickness changes, which are in accordance with the model, in different roller nips to each other, a chained model of the total system of the calender is formed. So the output data from the preceding roller nip is the calculated thickness change and then the same will be the input data of the thickness value to the following roller nip.
  • the adjustment of the thickness of the fibre web is a back fed adjustment, which utilises the estimated nip-specific prognosis of the line load and of the surface temperature given by the model, to reach the desired thickness
  • the adjustment of the thickness of the fibre web is an anticipating adjustment, which is based on the model.
  • FIG.l presents a finishing part, which is provided with covering unit, of the paper machine generally starting from the covering unit and ending to the reel-up unit, to which there is implemented the control and adjustment according to the invention are implemented,
  • FIG.2 presents the adjustment of the thickness of the paper web in a calender having two roller nips
  • FIG.3 presents the adjustment of the thickness of the paper in an OptiLoad calender, when a) an even distribution of a line load dominates and b) a change concerning the line loads takes place c) a parallel transfer of the distribution of the line load takes place and d) a discontinuous distribution of the line load dominates,
  • FIG.4 describes a modified OptiLoad calender, in which an upper set of rollers and a lower set of rollers are separately from each other so that a turn roller nip is open and in which the upper set of rollers and the lower set of rollers have the different distributions of the line loads, in which case it has been increased the opportunity to the control and to an one-sided gloss adjustment of the web,
  • FIG.5 presents a process state in the calender when the machine speed changes for the anticipating control and adjustment of the calender
  • FIG.6 presents the process state of the calender that is an up run, in which the machine speed is increased step by step.
  • the present invention can be adapted for both to so-called off-line calender constructions and to so called on-line calender constructions.
  • the finishing part includes furthermore i. dryers, advantageously infrared dryer 2 and float-up dryer 3, ii. cylinder dryer unit 4, iii. calender 5, which is in the example of figure 1 a multi-roller calender, which comprises soft surface polymer rollers 11 and/or paper rollers or other soft surface rollers as well as chill roller 10, one of which or more can be, typically, a hard thermo roller to be warmed.
  • dryers advantageously infrared dryer 2 and float-up dryer 3, ii. cylinder dryer unit 4, iii. calender 5, which is in the example of figure 1 a multi-roller calender, which comprises soft surface polymer rollers 11 and/or paper rollers or other soft surface rollers as well as chill roller 10, one of which or more can be, typically, a hard thermo roller to be warmed.
  • the present invention utilizes in this way, thickness and square weight measurements, which can be obtained from the quality measurement system.
  • the measuring stations of the quality measurement system for controlling the thickness of the fibre web in the calender 5, can locate before and after the calender 5, whereby there is one measuring station 9a of the thickness of the web before the calender and another measuring station 7 of the thickness of the web is after the calender.
  • the arrangement of the measuring station 7 can be arranged also so that only one measuring station 7, which in that case is located after the calender 5, will be used to adjust and to control the thickness of the fibre web W.
  • there is a reason to use the thickness values of the fibre web which are accomplished by the laboratory definitions instead of the values that are accomplished by the measuring station 9b, which precedes the calender 5.
  • a change in the thickness of the paper-taking place in each roller nip N can be determined by means of the model of the compressibility of the fibre web, such as.
  • the model equations of different roller nips By connecting the model equations of different roller nips to each other paper, the chained/linked model of the total system is obtained, hi that case, the change of the thickness of the paper, which was calculated in the previous roller nip, will be the output data that will be used as the input data of the thickness of the paper in the following roller nip .
  • the thickness of the fibre web is adjusted at the reel-up unit 6 is or adjusted a calender by utilising the paper, describing the compressibility model.
  • the model tries to pay attention to the effects of all the significant variables on the compressibility of the paper.
  • the unknown parameters which are included in a mathematical model, are determined with a recursive algorithm. Applying the recursive one has been known as such, which is why it has been brought out here only as a mention. Kalman filter method and the smallest square meter method sum can be mentioned as examples of the recursive algorithm.
  • Kalman filter method and the smallest square meter method sum can be mentioned as examples of the recursive algorithm.
  • With the help of the model is calculated to each roller nip N, such set values of the control and adjustment variables in order that the desired thickness of the paper will be reached.
  • a back fed adjustment is used for the adjustment of the thickness of the paper.
  • the adjustment will utilise nip-specific prognoses of the line load and of the surface temperature given by the model that have been estimated so that the desired thickness of the paper will be reached, h connections with the states of changes the machine speed either increases or decreases, an adjustment is carried out as an anticipating adjustment, which is based on the model.
  • Essential is that with the help of the model the validity of the prognosis values is verified at least on the thickness measuring 7 following the roller nip N or the calender 5. It is advantageous in that case to utilise thickness measuring 9a or the laboratory definition 9b of the thickness 5, which precedes the calender 5.
  • the compressibility model of the fibre web such as paper and the recursive updating of the parameters of the model are calculated either in an automation system or in a separate charge unit here in an immediate connection.
  • the compressibility model pays attention by binding the nip event to each other:
  • the model contains a group of parameters which depend only and only on the properties of the paper to be calendered. Coefficients of the model one can determine for example experimentally to each separate paper quality, where after the model can be applied to any calender 5 comprising a soft nip or a hard nip. Because a term, which would pay attention to the 10 flexibilities of the soft roller, is not included in the model equation, the model parameters are depending also from a calender to be used. However, the model can be applied when its coefficients are determined to each calender 5, separately. The most significant controlled variables by which have their effects traditionally to the thickness change, are the line load and the temperature of the chill roller 10.
  • Track speed and the radiuses of the rollers 10, 11 have an influence on the delay time in the roller nip N or the nip time, but in general the machine speed is tried to keep constant, except during the controlled speed changes.
  • the number of the unknown parameters of the model equation can be reduced in a controlled way.
  • the model describing the thickness change of the fibre web has been formulated according to the invention so that it is linear in regard to unknown parameters. So it is possible to apply directly different kind of off-line or on-line identification methods for the determination of the unknown parameters of the model. For example recursive method of the smallest square metre sum or of the Kalman filter is suitable for a task.
  • the model equation checks the validity of the identified parameters by comparing for example the actual value of the line load and the estimation of the line load that has been calculated with the help of the system model, one can conclude if the estimations reached of parameters are acceptable.
  • the acceptable functions point values of the parameters of the model equation of a paper species and process are saved in a separate database or to species recipes of the automation system, from which they can be brought into use when the paper species in question will come to the production.
  • the model based thickness regulator of the paper forms of the difference of a measured thickness value and of the desired thickness value a control message, which is based on the joined nip-specific compression model of the paper.
  • the model it is calculated to each roller nip N such set values of the control and adjusting variables that the desired final thickness value will be reached.
  • unknown parameters of the model have been determined or loaded from the database in the process conditions in question to paper species in the production, hi connection with the states of change of the machine speed the adjustment algorithm will calculate the need for change of the nip-specific line load and of the surface temperature of chill roller when the track speed changes.
  • the adjustment is carried out by a back fed adjustment, in which case the information about the thickness difference is formed on the basis of the set value and measuring of the thickness of the paper, on the basis of which thickness difference the adjustment algorithm makes the necessary changes in the line loads of roller nips and/or in the surface temperatures of the chill rollers or only in the line loads.
  • all the roller nips can be chosen to a computer adjustment.
  • FIG. 2 in which the adjustment of the thickness of the paper is presented in the calender comprising two roller nips, h that case the actual value of the thickness of the paper, which the adjustment programme compares with a set value, is obtained from the quality-measuring sensor of the measuring station 7 before the reeling-up or after the calender 5.
  • a corresponding total thickness ( ⁇ m) change is calculated on the basis of the thickness difference of the set value and of the measuring, which change the roller nips N were intended to bring about, which roller nips were selected to the computer adjustment.
  • N chosen to the computer adjustment with a relative weighting coefficient (0-100%) so that, however, the sum of weighting coefficients will be 100.
  • the present invention also covers the different ways to divide the thickness difference on the roller nips. In a relative distribution the share of the thickness difference shown by each weighting coefficient is directed to a chosen roller nip Ni.
  • the compressibility model of the paper is used when calculating the required changes in the set values of the controls of each roller nip ( ⁇ SetPoints). The new set values are transmitted after this to the unit control circuit, which will carry out the changes in the set values.
  • Figure 3 is referred to and a multi-roller OptiLoad calender and the different load situations will be next examined in the OptiLoad calender.
  • nip-specific load levels of upper roller nips are changed (figure 3b), in which case the load level of the lower roller nip remains unchanged, or the nip-specific load levels of the lower roller nips are changed (not presented), in which case the load level of the upper roller nip remains unchanged.
  • Figure 4 is referred to.
  • the invention can be adapted also to a modified OptiLoad calender, in which the rollers of the turn nip are fixed and/or can be positioned so that the turn nip can be open to form a separate upper set of rollers and a separate lower set of rollers, whereby the line load distribution can be adjusted in the upper set of rollers and in the lower set of rollers separately. Then the load of the upper set of rollers can be accomplished by the upper roller/rollers the load of the lower set of rollers can be accomplished by the lower roller/rollers.
  • both of the set of rollers can indeed be controlled by a different load distribution depending on the quality criteria.
  • the advantage is that the a one-sidedness of the paper can be better managed by connecting with each other for example the control of the temperature of chill roller and the control of vapour boxes set of roller specifically (the upper set of rollers / the lower set of rollers).
  • a glossy measuring also can be connected to a system. It is also possible to carry out control principles of the line load distribution of the normal OptiLoad calender, which were explained above in the connection of figure 3, in the upper set of rollers and in the lower set of rollers of the modified OptiLoad calender.
  • Figures 5 and 6 are referred to.
  • Figure 6 illustrates transmission of set values incrementally as distinct from figure 5.
  • OptiLoad will be first examined.
  • the set values of line load and/or of surface temperatures, which correspond to the point C, are calculated in the point A by means of the model so that corrections to the controls, which are caused of the change in the machine speed ( ⁇ Speed), are considered.
  • the new set values will be transmitted either immediately the change in the machine speed begins, that is, point A or incrementally during the change in the machine speed (FIG.6).
  • the size of the change in the machine speed and change time ( ⁇ T) affects this choice ( ⁇ L)
  • the set values of the surface temperature, which correspond to the point C can be transmitted already in the point (A '- 1) or to consider the slowness in the incremental distribution. If the up run of the machine will be made by using the phase B ', it is calculated, depending on time ( ⁇ T'), also the set values of the line loads and/or of surface temperatures, which correspond to the point B' and which are used as starting values when moving to the state C ⁇
  • the measure sensor of the quality measuring system can be in the partial profile measuring a so-called point measuring (non-traversing) or the measure sensor traverses only partly for example from a width of 0,5 - 1.0 m. In that case a correction will be always made to the set values on the basis of the model equation or on the basis of another correction calculation after the new reliable measurement data has completed.

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  • Paper (AREA)
  • Preliminary Treatment Of Fibers (AREA)

Abstract

L'invention concerne un procédé et un système de commande permettant de régler l'épaisseur d'une bande continue de matière fibreuse dans le sens machine, lorsque la feuille continue (W) devant être calandrée passe à travers un ensemble de rouleaux (10, 11) dans la calandre (5) d'une machine de production de bandes de matière fibreuse, cet ensemble de rouleaux comprenant une ou plusieurs lignes de pincement (N) entre les rouleaux. Dans le système et le procédé décrits, les valeurs de réglage des températures de la surface des rouleaux refroidisseurs (10) et les charges spécifiques dans les lignes de pincement entre les rouleaux sont calculées à l'aide d'un modèle de compression de la bande de matière fibreuse, permettant de sélectionner et de régler la compression.
PCT/FI2005/000079 2004-02-13 2005-02-07 Procede et systeme de commande permettant de regler l'epaisseur d'une bande continue de matiere fibreuse dans le sens machine WO2005078189A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI20045038A FI119113B (fi) 2004-02-13 2004-02-13 Säätömenetelmä ja -järjestelmä kuiturainan konesuuntaisen paksuuden säätämiseksi
FI20045038 2004-02-13

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WO2005078189A2 true WO2005078189A2 (fr) 2005-08-25
WO2005078189A3 WO2005078189A3 (fr) 2005-10-06

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PCT/FI2005/000079 WO2005078189A2 (fr) 2004-02-13 2005-02-07 Procede et systeme de commande permettant de regler l'epaisseur d'une bande continue de matiere fibreuse dans le sens machine

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FI (1) FI119113B (fr)
WO (1) WO2005078189A2 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008012735A3 (fr) * 2006-07-21 2008-04-03 Procter & Gamble Procédé de bobinage d'une bande substrat

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4429455A1 (de) * 1994-08-19 1996-02-22 Kleinewefers Gmbh Verfahren zum Verdichten einer Papierbahn und Preßwerk zur Durchführung des Verfahrens
FI116403B (fi) * 2000-09-18 2005-11-15 Metso Paper Inc Menetelmä kalanteroitavan paperirainan ominaisuuden säätämiseksi

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008012735A3 (fr) * 2006-07-21 2008-04-03 Procter & Gamble Procédé de bobinage d'une bande substrat
US7484686B2 (en) 2006-07-21 2009-02-03 The Procter & Gamble Company Process for winding a web substrate

Also Published As

Publication number Publication date
WO2005078189A3 (fr) 2005-10-06
FI20045038L (fi) 2005-08-14
FI119113B (fi) 2008-07-31
FI20045038A0 (fi) 2004-02-13

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