WO2001065004A1 - Procede et agencement de regulation de la consistance de la pate a papier - Google Patents

Procede et agencement de regulation de la consistance de la pate a papier Download PDF

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Publication number
WO2001065004A1
WO2001065004A1 PCT/FI2001/000209 FI0100209W WO0165004A1 WO 2001065004 A1 WO2001065004 A1 WO 2001065004A1 FI 0100209 W FI0100209 W FI 0100209W WO 0165004 A1 WO0165004 A1 WO 0165004A1
Authority
WO
WIPO (PCT)
Prior art keywords
consistency
pulp mixture
flow rate
white water
pulp
Prior art date
Application number
PCT/FI2001/000209
Other languages
English (en)
Inventor
Pasi Virtanen
Jussi Ahola
Elina Pohjala
Sakari Soini
Veli-Matti Rajala
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
Priority to AU2001239336A priority Critical patent/AU2001239336A1/en
Publication of WO2001065004A1 publication Critical patent/WO2001065004A1/fr

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Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F1/00—Wet end of machines for making continuous webs of paper
    • D21F1/08—Regulating consistency

Definitions

  • the invention relates to a method for adjusting the properties of pulp mixture fed into the headbox of a paper machine, in which method at least one high-consistency pulp mixture and white water containing fibres and obtained from the paper machine cycle are mixed together to produce a pulp mixture of required quality for the purpose of feeding it into the headbox in such a manner that the flow rate of the pulp mixture obtained as a result of the mixing and fed into the headbox is substantially constant, whereby the consistency of the high-consistency pulp mixture is measured before mixing it with white water and the flow rate of the high-consistency pulp mixture is adjusted on the basis of the measured consistency so that the consistency of the pulp mixture made up of white water and high-consistency pulp mixture and fed into the headbox is substantially as required.
  • the invention further relates to an arrangement for adjusting the properties of pulp fed into the headbox of a paper machine when mixing together at least one high-consistency pulp mixture and white water containing fibres and obtained from the paper machine cycle to produce a pulp mixture of required quality for the purpose of feeding it into the headbox in such a manner that the flow rate of the pulp mixture obtained as a result of the mixing and fed into the headbox is substantially constant, which arrangement comprises measuring means for measuring the consistency of the high- consistency pulp mixture before mixing it with white water, and means for adjusting the flow rate of the high-consistency pulp mixture on the basis of the measured consistency so that the consistency of the pulp mixture made up of white water and pulp mixture and fed into the headbox is substantially as required.
  • pulp components are mixed together to form a pulp mixture of required quality for the headbox of a paper machine.
  • Typical pulp components are the actual high-consistency pulp mixture and different water-fibre mixtures containing less fibre than the actual high-consistency pulp mixture, i.e. white waters, such as filtrate waters, dilution waters and the like.
  • the dosage and mixing together of the pulp components is typically done by directing these substantially liquid mixtures into a container in which they are mixed together by mechanical mixers.
  • solutions are to some extent used, in which different pulp components are mixed in a conical pipe in such a manner that the pulps fed in at different rates mix together as a result of the turbulence caused by the differences in rate.
  • high-consistency pulp mixture refers to a pulp mixture having a higher consistency than that suitable for feeding into the headbox of a paper machine, which means that the high-consistency pulp mixture needs to be diluted to obtain a consistency suitable for the headbox.
  • the method of the invention is characterized in that before mixing a high-consistency pulp mixture and white water, the consistency of the white water is measured, and that the flow rate of the high-consistency pulp mixture is adjusted on the basis of the measured consistency values in such a manner that the consistency of the pulp mixture fed into the headbox is as required.
  • the arrangement of the invention is characterized in that the arrangement comprises means for measuring the consistency of white water, and that means for adjusting the flow rate of the high-consistency pulp mixture are set to adjust the flow rate on the basis of the measured consistency values.
  • the essential idea of the invention is that the consistency of the white water fed into the headbox is measured and it is taken into account together with the consistency of the high-consistency pulp mixture when adjusting the flow rate of the high-consistency pulp mixture in such a manner that the consistency of the pulp mixture fed into the headbox and thus the pulp flow and also the consistency of the pulp mixture fed into the headbox remain as required, i.e. substantially constant during constant production.
  • the essential idea of a preferred embodiment of the invention is that because the flow rate of the pulp mixture fed into the headbox is substantially constant, the consistency of both the tail water and the high-consistency pulp mixture is taken into account in the adjustment, and the flow rate of the high-consistency pulp mixture is adjusted so that the final result is a substantially constant pulp flow.
  • the essential idea of a second preferred embodiment of the invention is that if the ratio of the flow rates of the high-consistency pulp mixture and white water tries to decrease below a suitable mixing ratio according to a predefined limit value, the consistency of the high-consistency pulp mixture is adjusted by feeding separately into it, before mixing the high-consistency pulp mixture and the white water, a dilution liquid having a lower consistency than the high- consistency pulp mixture so that the consistency of the pulp mixture fed into the headbox, and thus also the pulp flow, remains substantially constant.
  • the invention is based on the fact that because the flow rate of the pulp mixture exiting the slice of the headbox is substantially constant, the sum flow rate of the pulp mixture fed into the headbox is formed in such a manner that when the flow rate of the high-consistency pulp mixture to be mixed has been adjusted, the part of the total flow rate remains for the white water to be mixed, which is formed of the difference between the flow rate exiting the headbox and the flow rate of the high-consistency pulp mixture to be added to the mixture.
  • the ratio of the pulp mixture and white water is adjusted at the same time, and consequently also the consistency of the pulp mixture obtained as a result of the mixing, fed into the headbox and having a constant flow rate, and correspondingly the pulp flow entering the headbox.
  • the invention provides the advantage that quality variations of a fibre web made in this manner decrease considerably, because the consistency of the pulp mixture exiting the headbox remains substantially constant regardless of the consistency variations of the high-consistency pulp mixture and white water being fed into the headbox. Because the adjustment is also easily made by adjusting mainly only the flow rate of the high- consistency pulp mixture on the basis of the measured consistencies of the white water and high-consistency pulp mixture, the adjustment is reliable and easy to implement. [0008] The invention is described in greater detail in the attached drawings in which
  • Figure 1 is a schematic of an apparatus suited for implementing the method of the invention
  • Figure 2 is a schematic of a second apparatus suited for implementing the method of the invention.
  • Figure 1 shows a schematic of the structure of the so-called wet end of a paper machine and the related liquid circulation.
  • the figure shows a headbox, marked by number 1 , from which pulp mixture is fed to a former, marked by arrow 2.
  • a former water is drained from the pulp mixture in a manner known per se between wires, the wires being shown here schematically only and marked by numbers 3 and 4.
  • Water drains from the pulp mixture between the wires and later in the section of the former, after which the fibre web moves as shown by arrow 5 onward in a manner known per se in the paper machine and the drained water, i.e.
  • the white water is returned back to the cycle as shown by arrow 6.
  • the white water can be tail water or other typical water containing fibre to some extent, separated at a suitable stage from the paper machine and suited for reuse in the cycle of the paper machine.
  • When feeding a high-consistency pulp mixture into the headbox 1 it is diluted with said white water so as to make the consistency c of the pulp mixture entering the headbox as required.
  • the flow rate Q of the pulp mixture remains substantially constant, because it is entirely proportional to the pulp spray exiting the slice of the headbox 1 , the spray being kept substantially constant by headbox adjustments in a manner known per se.
  • the purpose of this invention is to produce a result, in which the pulp flow m' of the pulp mixture entering the headbox 1 also remains constant and the consistency variations of both the high-consistency pulp mixture and the white water are taken into account in the adjustment.
  • Figure 1 also shows a pulp container 7 with a pulp channel 8 leading to a pump 9.
  • the pump 9 is controlled by a control unit 10 which measures the flow rate and consistency of the high-consistency pulp mixture in the forward-leading pulp channel 8 after the pump 9 and adjusts the pump 9 on the basis of pre-set values.
  • the pulp channel 8 continues to a mixing unit 11 , in which the pulp components are mixed in a closed space.
  • the mixing unit 11 the high-consistency pulp mixture from the pulp container 7 and the white water from the paper machine mix so that their sum flow rate is constant. This is due to the flow rate Q, of the high- consistency pulp mixture being adjusted, whereby the difference between the flow rate Q of the mixed pulp mixture going from the pump 12 to the headbox and the flow rate Q, of the pulp mixture exiting from the pulp container 7 remains as the flow rate Q 0 of the white water.
  • the flow rate of the high-consistency pulp mixture exiting the pulp container 7 can be adjusted so that the pulp flow m' 0 of the white water and the pulp flow m'., of the pulp mixture are, when summed, the required pulp flow m' of the pulp mixture, which is needed to make the required homogeneous- quality fibre web.
  • the pulp flow m' is constant and the flow rate of the pulp mixture entering the headbox is constant, the consistency is constant.
  • the unit 13 is most preferably connected to the pulp channel 8 before the pump 9, in which case the fed dilution liquid and the high-consistency pulp mixture mix well by means of the pump.
  • the flow rate of the high-consistency pulp mixture exiting the pump 9 is kept constant and the consistency of the high-consistency pulp mixture is adjusted by adjusting the flow of the dilution liquid to the pulp channel 8.
  • the dilution liquid is water which contains fibre, it has, when being mixed, a certain flow rate Q 2 , consistency c 2 , and as a result thereof a pulp flow m' 2> on the basis of which the properties of the resulting diluted high-consistency pulp mixture can be calculated.
  • Figure 2 shows a solution similar to Figure 1 except that in it, the invention has been applied to a situation in which two pulp mixtures having different consistencies are mixed before the pulp mixture is mixed with the white water.
  • an additional definition 'first' is used for components corresponding to those in Figure 1 to distinguish them from the corresponding components shown a second time in Figure 2.
  • Figure 2 has a second pulp container 14, from which a second pulp channel 15 runs to a pump 16, which corresponding to the pump 9 is controlled by a control unit 17 which measures from the second pulp channel 15 leading from the pump 16 onward, the flow rate Q 3 and consistency c 3 , by means of which the pulp flow m' 3 of the second high- consistency pulp mixture exiting the second pulp container can be correspondingly calculated and the pump 16 correspondingly adjusted on the basis of these measurements and the given control values.
  • the second pulp channel 15 continues to a mixing unit 18, where the first high-consistency pulp mixture from the first pulp channel 8 is mixed with the second high-consistency pulp mixture from the second pulp channel 15, and the resulting mixture flows on along a transport channel 19.
  • the flow rate of the high- consistency pulp mixtures exiting the containers 7 and 14 is most preferably adjusted independent of each other.
  • the flow rate of the sum flow in the transport channel 19 is the sum of the flow rates from the pulp channels 8 and 15, and a change in the flow rate of one of the pulp channels causes a corresponding change in the sum flow rate in the same direction without changing the quantitative proportion of the second high-consistency pulp mixture of the sum flow rate.
  • increasing the flow rate of the first pulp channel 8 increases the sum flow rate by an equal amount and decreasing it correspondingly decreases the sum flow rate by an equal amount.
  • a change in the flow rate of the second pulp channel 15 changes the sum flow rate by a corresponding amount.
  • the adjustment can be made in such a manner that when the consistency tries to decrease, the flow rate is reduced in a pulp channel which has a high-consistency pulp mixture having a lower than the required consistency, and the flow rate of a pulp channel which has a high-consistency pulp mixture having a higher than the required consistency is increased by a corresponding amount, whereby the changes in flow compensate each other and the consistency is kept as required.
  • the amounts of the lower-consistency and higher-consistency pulp mixture flow rates are correspondingly changed to the same extent in opposing directions so that the consistency changes on a required level.
  • the flow rates are increased or decreased when the consistency of the pulps in the containers 7 and 14 change, so that the consistency of the resulting sum flow rate of the high-consistency pulp mixtures remains the same.
  • the method of the invention can adjust the pulp flow m' of the pulp mixture entering the headbox and thus also the consistency c so that the quality of the formed fibre web remains as good as possible.
  • the second high-consistency pulp mixture can be adjusted by feeding into the second pulp channel 15 through a unit 20 dilution liquid, which can be water or a water mixture containing fibres.
  • a unit 20 dilution liquid which can be water or a water mixture containing fibres.
  • arrow 21 in Figure 2 indicates the connection of the adjustment system to an external computer or a network for the purpose of controlling the adjustments as required.
  • the essential thing in the invention is that the consistency of both the white water and the high-consistency pulp mixture to be mixed are measured and the pulp flow rate of at least one high-consistency pulp mixture to be mixed with the white water is adjusted so that the pulp flow, and at the same time, consistency, of the pulp mixture entering the headbox remain substantially constant in spite of the consistency variations in the high-consistency pulp mixture and/or white water.
  • the figure only shows schematically the mixing and dosage of two different high-consistency pulp mixtures, the same principle applies to mixing several pulp mixtures into the same sum channel. This is most preferably done by combining the pulp channels of each pulp mixture in a common mixing unit, whereby the mixing is easy.
  • An essential advantage of an embodiment of the invention is also that because both the flow rate and consistency are measured from each pulp channel coming in for mixing, the flow rate amount and consistency of the sum flow of the pulp mixture can be calculated directly without having to measure it separately from the transport channel of the sum flow.
  • the adjustment can be made directly on the basis of the measurement results of each pulp channel and, when making the adjustment, it is also possible to take into account the effect of a pulp mixture from possible mixings at other later paper-making process stages, if required.

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  • Paper (AREA)

Abstract

L"invention concerne un procédé et un agencement de régulation des propriétés d"une pâte à papier à introduire dans la caisse de tête d"une machine à papier. Dans cette invention, la consistance de l"eau blanche à déverser dans la caisse de tête est mesurée et prise en compte avec la consistance d"un mélange de pâte à papier de consistance élevée, lors de la régulation du débit du mélange de pâte de haute consistance, de sorte que la consistance du mélange de pâte à papier introduit dans la caisse de tête, donc le flux et la consistance du mélange de pâte introduit dans la caisse de tête restent conformes aux exigences, c"est-à-dire sensiblement constants au cours de la production en continu.
PCT/FI2001/000209 2000-03-02 2001-03-02 Procede et agencement de regulation de la consistance de la pate a papier WO2001065004A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2001239336A AU2001239336A1 (en) 2000-03-02 2001-03-02 Method and arrangement for adjusting pulp consistency

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI20000486 2000-03-02
FI20000486A FI114224B (fi) 2000-03-02 2000-03-02 Menetelmä ja sovitelma syötettävän kuitumassaseoksen sakeuden säätämiseksi paperikoneen perälaatikolle

Publications (1)

Publication Number Publication Date
WO2001065004A1 true WO2001065004A1 (fr) 2001-09-07

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Application Number Title Priority Date Filing Date
PCT/FI2001/000209 WO2001065004A1 (fr) 2000-03-02 2001-03-02 Procede et agencement de regulation de la consistance de la pate a papier

Country Status (3)

Country Link
AU (1) AU2001239336A1 (fr)
FI (1) FI114224B (fr)
WO (1) WO2001065004A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003034170A1 (fr) * 2001-10-19 2003-04-24 Metso Automation Oy Procede et appareil pour commander le fonctionnement de l'unite de preparation de la pate dans une machine a papier
CN110468619A (zh) * 2019-09-24 2019-11-19 广西贺州市红星纸业有限公司 一种基于中高浓制浆造纸技术的浓度调节方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998030751A1 (fr) * 1997-01-07 1998-07-16 Ecopump Oy Procede servant a regler la consistance d'une pate a papier
WO1998032916A1 (fr) * 1997-01-24 1998-07-30 Valmet Corporation Procede et appareil de regulation de la caisse de tete d'une machine a papier

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998030751A1 (fr) * 1997-01-07 1998-07-16 Ecopump Oy Procede servant a regler la consistance d'une pate a papier
WO1998032916A1 (fr) * 1997-01-24 1998-07-30 Valmet Corporation Procede et appareil de regulation de la caisse de tete d'une machine a papier

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003034170A1 (fr) * 2001-10-19 2003-04-24 Metso Automation Oy Procede et appareil pour commander le fonctionnement de l'unite de preparation de la pate dans une machine a papier
CN100354783C (zh) * 2001-10-19 2007-12-12 麦特自动有限公司 控制造纸机的备料作业的方法和装置
CN110468619A (zh) * 2019-09-24 2019-11-19 广西贺州市红星纸业有限公司 一种基于中高浓制浆造纸技术的浓度调节方法

Also Published As

Publication number Publication date
FI114224B (fi) 2004-09-15
FI20000486A0 (fi) 2000-03-02
AU2001239336A1 (en) 2001-09-12
FI20000486A (fi) 2001-09-03

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