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WO2004076739A1 - Procede de commande d'un processus permettant de produire de la pate mecanique raffinee - Google Patents

Procede de commande d'un processus permettant de produire de la pate mecanique raffinee Download PDF

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Publication number
WO2004076739A1
WO2004076739A1 PCT/FI2003/000136 FI0300136W WO2004076739A1 WO 2004076739 A1 WO2004076739 A1 WO 2004076739A1 FI 0300136 W FI0300136 W FI 0300136W WO 2004076739 A1 WO2004076739 A1 WO 2004076739A1
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WO
WIPO (PCT)
Prior art keywords
control
refining
speed
wood
refiner
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.)
Ceased
Application number
PCT/FI2003/000136
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English (en)
Inventor
Tom Forsman
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.)
Individual
Original Assignee
Individual
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 Individual filed Critical Individual
Priority to PCT/FI2003/000136 priority Critical patent/WO2004076739A1/fr
Priority to AU2003206986A priority patent/AU2003206986A1/en
Publication of WO2004076739A1 publication Critical patent/WO2004076739A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21D—TREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKING MACHINE
    • D21D1/00—Methods of beating or refining; Beaters of the Hollander type
    • D21D1/002—Control devices
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21D—TREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKING MACHINE
    • D21D1/00—Methods of beating or refining; Beaters of the Hollander type
    • D21D1/20—Methods of refining
    • D21D1/30—Disc mills

Definitions

  • the present invention relates to a method for controlling refining process, in order to reach an optimal value for the quality of the pulp characteristics and for the energy consumption of the process.
  • the construction of a refiner is well known.
  • the grinding of wood in the refiner is normally done between two discs of which the first one (the rotor) rotates while the second (the stator) stays still. It is also possible that both the discs are rotated.
  • a refining zone is formed between the two discs. So-called refining segments are fastened on the walls against each other of the refining discs.
  • the refiner is fed with wood chips near the midpoint of the refining discs.
  • the wood is transported between the discs from the near midpoint to the periphery of the discs, while the wood is fibrillated at the same time. Ready refining pulp is taken from the periphery of the discs.
  • the split between the refiner discs where the wood is refined and transported is called refining split.
  • the distance between the discs i.e. the width of the refining split is normally adjustable.
  • the refining process has a long time been fairly unknown.
  • First in 1985 knowledge on its base phenomenon was gained by filming the events in the refining split with a special camera.
  • the chips turn into fibres immediately after their feeding in the refining split.
  • the fibrillation takes place just before the outer periphery of the refining segments.
  • thermo mechanical pulp (TMP) has been thought to be a very stochastic process. Reliable measurements are difficult to carry out and the control of the process has up to now been more like art than science.
  • a refining process has active variables, which can be changed, and passive variables, which have their optimal values, which always are kept constant. According to traditional control philosophies the active variables, which affect the refining, are, for example - production or mass stream wood through the refiner discs,
  • the specific energy requirement SER (calculated as total refining effect in MW divided with the production in ton/h) has for a long time been an important control variable, because the energy consumption is relative high in comparison with the grinding process.
  • Passive variables are for example:
  • the quality criterion is freeness (CFS).
  • SER and the refining consistence are the best control variables.
  • SER affects at the same time the long fibre fraction in the pulp and the peak content at a constant SER.
  • the refining consistence is controlled with mass- and energy balances.
  • the quality criteria are CFS, long fibre fraction and peak content.
  • CFS is measured on-line with a commercial meter. To reduce the quality variations by half, there has to be done at least three control steps in an hour.
  • Alsip 141 has similar strategy with the aforementioned one, but control of the refiner effects is done in a different way.
  • the aim of this invention is to get a method for controlling the refining process where the aforementioned problems have been minimized.
  • a special aim for this invention is to accomplish a method for controlling the refining process with which an optimal pulp quality is reached, i.e. in such a way that an optimal value is reached for characteristics of the pulp quality.
  • One aim is also to optimise the energy consumption for the refining process.
  • control variable In practice the speed of revolutions of the feeding screw, which feeds the wood to the refiner, is used as control variable.
  • the control variables affect the quality i.e. measuring variables: CFS and possible fibre distribution, tear and tensile, to some extent because the impact of the control variables on the measuring variables can be coupled.
  • the present invention it is consequently for example possible to control with the new multivariable method CFS and fibre distribution with the mass flow at the same time when the fibre strength properties (tear, tensile) are controlled with the refiner split.
  • the refiner is controlled with two input signals and two output signals.
  • a third degree of freedom can be used in the multivariable controlling. As such can function the rotation speed of the rotor or the rotation force of the motor, which rotates the rotor. With these it is possible also to control the quality (for example tear). By varying the rotation speed or rotation force of the motor it is also possible to better optimise the energy requirement (SER). In other words it is possible to reduce the energy consumption if so desired.
  • SER energy requirement
  • Figure 1 shows schematically a usual refiner
  • Figure 2 shows a typical structure of a refining disc
  • Figure 3 is an enlargement from one part of Figure 2.
  • FIG. 1 shows the refiner 1 in which only one of the refining discs, with other words the rotor 5 is rotated. It is of course possible to arrange the refiner 1 of the invention so that both refining discs 4 and 5 are rotated.
  • the rotor 5 is rotated with axle 6, which is rotated with a motor, which is not shown in the figures.
  • the rotation force and/or the rotation speed of the motor are advantageously controllable.
  • u is the input vector and y is the output vector
  • ⁇ e(t) ⁇ is a sequence of independent evenly distributed random vectors with a mean value of zero and the covariance
  • the dimension of all vectors u, y and e is p, and the dimension of all matrices A ir B and Cj . is pxp .
  • the matrix B 0 is non-singular.
  • B B((zz)) B B 00 ++ BBiizz ++ ... + + BB nn ..iZ
  • the adaptive algorithm performs an identification based on the least squares method according to the model presented below.
  • the algorithm estimates the parameters for the model
  • k is selected as the dead time for the process (2), and A(z) and B(z) are pxp polynomial matrices according to
  • A(z) A 0 + A iZ + ... + - A ZI1A
  • B 0 is a matrix in the constant term of B(z) for the process ( 2 ) .
  • ⁇ (t-k-l) [-y ⁇ (t-k-l) ... -y T (t-k-l-n A )
  • the i c row in model (3) can be written as
  • the criterion (6) can be written as
  • the parameters for the controller are the same as the estimated parameters .
  • the estimated parameter vector ⁇ L in (8) can be recursively calculated from
  • K(t-l) P(t-l) ⁇ ⁇ (t-k-l) [l+ ⁇ (t-k-l)P(t-l) ⁇ ⁇ (t-k-l) ] _1 (13)
  • P(t) is a normalised covariance matrix of the estimated
  • the covariance matrix P(t) is supplemented by adding to it a matrix R x instead of the division by ⁇ .
  • P(t) P(t-1)-K(t-1) [l+ ⁇ (t-k-l)P(t-l) ⁇ T(t-k-1) ]
  • the algorithm can be construed as a union of a plurality (here 2) of simple self-adjusting controllers.
  • the controller 2 controls the output signal y ( t ) by using the control variable u 2 ( t ) .
  • y t (t-i) and u ⁇ t-l-i) (i > 0) can be used as feedforward signals.
  • the two simple self-adjusting controllers can operate in a cascade mode.
  • Another possibility is an exclusively multivariable minimum variance control algorithm, which is not adaptive. It is eventually possible to use another type of controlling than stochastic control.

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  • Paper (AREA)

Abstract

L'invention concerne un procédé permettant de commander un processus servant à produire de la pâte raffinée. Le procédé selon l'invention est commandé au moyen d'un algorithme de commande multivariable, au moins deux des paramètres figurant ci-après étant simultanément utilisés en tant que variables de commande : a) le débit massique de bois ou la vitesse de rotation de la vis d'alimentation ; b) la largeur de l'interstice de raffinage ; c) la vitesse de rotation du rotor ou sa vitesse périphérique ; d) la force de rotation du moteur. Dans ce système, au moins deux variables de mesure sont utilisées. Une de ces variables est la déchirure et est couplée à au moins une desdites variables de commande a), b), c) ou d).
PCT/FI2003/000136 2003-02-27 2003-02-27 Procede de commande d'un processus permettant de produire de la pate mecanique raffinee Ceased WO2004076739A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
PCT/FI2003/000136 WO2004076739A1 (fr) 2003-02-27 2003-02-27 Procede de commande d'un processus permettant de produire de la pate mecanique raffinee
AU2003206986A AU2003206986A1 (en) 2003-02-27 2003-02-27 Control method of a process for producing refiner mechanical pulp

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/FI2003/000136 WO2004076739A1 (fr) 2003-02-27 2003-02-27 Procede de commande d'un processus permettant de produire de la pate mecanique raffinee

Publications (1)

Publication Number Publication Date
WO2004076739A1 true WO2004076739A1 (fr) 2004-09-10

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/FI2003/000136 Ceased WO2004076739A1 (fr) 2003-02-27 2003-02-27 Procede de commande d'un processus permettant de produire de la pate mecanique raffinee

Country Status (2)

Country Link
AU (1) AU2003206986A1 (fr)
WO (1) WO2004076739A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2045057A1 (fr) * 2007-10-03 2009-04-08 T.P.F. Management Procédé de fabrication de biocarburant
WO2011045090A1 (fr) * 2009-10-14 2011-04-21 Abb Research Ltd Technique et système pour broyer un matériau fibreux avec rendement d'énergie et qualité de pâte améliorés

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997049857A1 (fr) * 1996-06-25 1997-12-31 Tom Forsman Procede de commande d'une operation de reduction de bois en pate mecanique

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997049857A1 (fr) * 1996-06-25 1997-12-31 Tom Forsman Procede de commande d'une operation de reduction de bois en pate mecanique

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2045057A1 (fr) * 2007-10-03 2009-04-08 T.P.F. Management Procédé de fabrication de biocarburant
WO2009043932A1 (fr) * 2007-10-03 2009-04-09 T.P.F. Management Processus de production pour un biocarburant
WO2011045090A1 (fr) * 2009-10-14 2011-04-21 Abb Research Ltd Technique et système pour broyer un matériau fibreux avec rendement d'énergie et qualité de pâte améliorés
CN102666977A (zh) * 2009-10-14 2012-09-12 Abb研究有限公司 具有改进的能量效率和纸浆质量的用于磨制纤维材料的过程和系统
CN102666977B (zh) * 2009-10-14 2016-02-24 Abb研究有限公司 具有改进的能量效率和纸浆质量的用于磨制纤维材料的过程和系统

Also Published As

Publication number Publication date
AU2003206986A1 (en) 2004-09-17

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