US20040011483A1 - Method and apparatus and screen for screening mechanical fiber pulp - Google Patents

Method and apparatus and screen for screening mechanical fiber pulp Download PDF

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Publication number
US20040011483A1
US20040011483A1 US10/414,816 US41481603A US2004011483A1 US 20040011483 A1 US20040011483 A1 US 20040011483A1 US 41481603 A US41481603 A US 41481603A US 2004011483 A1 US2004011483 A1 US 2004011483A1
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US
United States
Prior art keywords
pulp mixture
fiber pulp
screen
gap
output port
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.)
Abandoned
Application number
US10/414,816
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English (en)
Inventor
Jouko Hautala
Vesa Juutinen
Erkka Nieminen
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.)
Valmet Technologies Oy
Original Assignee
Metso Paper Oy
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 Oy filed Critical Metso Paper Oy
Assigned to METSO PAPER INC. reassignment METSO PAPER INC. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: HAUTALA, JOUKO, JUUTINEN, VESA, NIEMINEN, ERKKA
Publication of US20040011483A1 publication Critical patent/US20040011483A1/en
Assigned to VALMET TECHNOLOGIES, INC. reassignment VALMET TECHNOLOGIES, INC. CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). Assignors: METSO PAPER, INC.
Abandoned legal-status Critical Current

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    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21D—TREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKING MACHINE
    • D21D5/00—Purification of the pulp suspension by mechanical means; Apparatus therefor
    • D21D5/02—Straining or screening the pulp

Definitions

  • the invention relates to a method for screening a mechanically manufactured fibre pulp mixture containing fibres of varying lengths, in which method the fibre pulp mixture obtained by mechanically defibering wood in the presence of water is screened into at least two fractions containing fibres of mainly varying lengths.
  • the invention also relates to an apparatus for screening a mechanically manufactured fibre pulp mixture containing fibres of varying lengths, the apparatus comprising screening means for screening the fibre pulp mixture obtained by mechanically defibering wood in the presence of water into at least two fractions containing fibres of mainly varying lengths.
  • the invention further relates to a screen for screening a mechanically manufactured fibre pulp mixture containing fibres of varying lengths into two fractions containing fibres of substantially varying lengths, the screen comprising at least one screening surface through which water is removed from the fibre pulp mixture and some of the shorter fibres with the water and the remaining fibre pulp mixture is removed from the screen from the same side of the screening surface to which the fibre pulp mixture was fed.
  • the fibre material is screened in the prior art methods using screens comprising various screening surfaces so that fibres, which are smaller than a particular size and which have passed through a screening surface, are directed for use, and the coarser fibres are removed from the process and returned again to the process through reject refining.
  • the final result is a fibre pulp mixture, where the lengths of the fibres and thus their freeness values vary widely, and the structure of the fibre pulp mixture and the properties thereof do not correspond with the desired ones.
  • the method of the invention is characterized in that in at least one screening phase the fibre pulp mixture or a part thereof is screened to separate short fibres from the fibre pulp mixture or from a part thereof using a gap screen comprising a convergent gap and at least one wire restricting said gap, whereby the fibre pulp mixture to be screened or a part thereof is fed into said convergent gap so that it flows in the same direction as the wire towards an output port at the convergent end of the gap, and the short fibres and some of the water fed into the gap exit through the openings in the wire whereas the water and some of the remaining fibre pulp mixture exit through the output port of the gap.
  • the apparatus of the invention is characterized in that the apparatus comprises a gap screen to separate short fibres comprising a convergent gap and at least one wire restricting said convergent gap, whereby the fibre pulp mixture to be screened or a part thereof is fed into said convergent gap so that it flows through the gap screen in the same direction as the wire towards the convergent end of the gap so that the short fibres and some of the water exit through the openings in the wire and the remaining part of the fibre pulp mixture exits from the gap screen through the output port at the convergent end of the gap.
  • the screen of the invention is characterized in that the screen is a gap screen comprising a convergent gap restricted by a wire and into which the fibre pulp mixture is fed to move in the same direction as the wire, whereby water and shorter fibres exit through the openings in the wire and the remaining fibre pulp mixture exits from the output port at the convergent end of the gap.
  • An essential idea of the invention is that an extremely fine and short-fibered fibre pulp material is separated from the fibre pulp mixture using a gap screen, preferably one formed by means of twin wires, whereby a very short-fibred material having a high freeness value is obtained that cannot be so distinctly distinguished as a specific pulp by means of other screening methods.
  • a part of a fibre pulp mixture containing medium-length and shorter fibre materials preferably already screened by separating long fibres therefrom is screened anew using said gap screen formed by means of twin wires.
  • the medium-sized fibre material containing some fine fibres separated from the gap screen is directed further to be refined. As a result a fraction containing medium-sized and short fibres with the desired properties is obtained.
  • the invention provides such an advantage that a fibre fraction that is shorter than a fraction representing a particular length can be very accurately separated from the fibre pulp mixture containing fibres of varying lengths.
  • An advantage provided by a preferred embodiment of the invention is that as the long-fibred fibre material is at first screened and thereafter a very short fibre material having a high freeness value is separated using the gap screen from the remaining fraction containing medium-sized and short-fibred material, then the final result obtained is three fibre pulp fractions with different properties that can be mixed with one another or with other fibre materials in order to achieve a desired fibre web quality.
  • long fibres can be combined with very short fibres in order to obtain a particular paper quality, which is not possible when medium-sized fibres are included in the fibre pulp.
  • fibre pulp fractions of varying properties and lengths can be obtained as desired from the mechanically manufactured fibre pulp, and thereby the desired fractions can easily be combined with the manufacturing of fibre web, and only the fibre pulp fractions required can be used to produce a particular type of fibre web.
  • a fibre web that contains only long or short fibres can be manufactured and the medium-sized fibre obtained can be used to produce another type of fibre web.
  • FIG. 1 schematically shows the method and apparatus of the invention
  • FIG. 2 schematically shows a gap screen to be used in the application of the method of the invention
  • FIG. 3 schematically shows a screening result obtained using the gap screen of the invention.
  • FIG. 1 schematically shows the method and apparatus of the invention, in which freeness values of a particular fibre pulp are provided by way of example, on the basis of which values the division into different fibre pulp fractions can be carried out.
  • FIG. 1 schematically shows how a material 1 to be defibered is directed to a defibrator 2 , which may be a grinder known per se or a refiner, typically a thermomechanical pulp refiner.
  • the fibre pulp mixture obtained from defibration is directed to screening means, or at first to a first screen 3 , where the mixture can be divided for example in accordance with freeness value “16” so that the fraction containing long fibres and has passed through the first screen 3 proceeds to be further processed and the fraction containing even longer fibres and shives and has not passed through said screen is directed to be refined to a first recirculation refiner 4 , from where the fraction is returned to the first screen 3 for screening.
  • the first refiner may either be a separate refiner, or the fraction to be returned can also be returned to the actual defibrator 2 as indicted by the dashed line.
  • the fibre pulp fraction containing long fibres and has passed through the first screen is directed forward to a second screen 5 , where the fraction is screened again according to length on the basis of the fibre length provided by way of example with freeness value “28”.
  • the fibre pulp fraction that has passed through the second screen 5 continues forward to be further processed and the longer fibre pulp fraction that is unable to pass through said screen is directed to a second refiner 6 , which is preferably a refiner known per se.
  • the fibre pulp obtained from the second refiner 6 is directed to a third screen 7 , from where the fibre that is shorter than a particular length and that has passed through said screen, for example a fibre provided with freeness value “40” is directed forward for use, and correspondingly the fibre that is unable to pass through the screen 7 is returned again to the second refiner 6 to be refined.
  • the long fibre circulates the same loop until it is shortened to a desired size in such a manner that it passes through the third screen 7 and is then ready for use.
  • the fibre pulp fraction that has passed through the second screen 5 is directed in accordance with the invention to a fine screening 8 , where a fine fibre pulp fraction is separated from the fibre pulp using a separate gap screen, for example fibres provided with a freeness value of at least “200” and correspondingly fibres that are longer than that are directed to a third refiner 9 , which preferably is a refiner known per se.
  • the fibre pulp fraction obtained from the output of the third refiner 9 contains high-quality fines and medium-sized fraction.
  • the gap screen is either a single wire or twin wire structured screen. Such a screen can be used to efficiently remove a desired amount of fibre pulp of a particular length or shorter than that from the fibre pulp mixture, thus making the division between the fractions drastic and providing a desired ratio.
  • the other screens are screens known as such either so that each screen represents a separate individual screen or that two or more screens form one multi-phase screen. Then again it is necessary to use a gap screen to separate short fibres.
  • FIG. 2 schematically shows gap a twin wire structured screen 10 .
  • the gap screen preferably allows to screen the fibre pulp into two fractions in accordance with the invention.
  • the gap screen comprises two movable wires 11 and 12 forming opposing screening surfaces that move through the gap screen and return as closed loops so as to form a convergent gap 13 within the gap screen in the direction of movement thereof.
  • Supporting structures 14 and 15 are placed at the back of the wires 11 and 12 , i.e. on the opposite side of the gap 13 .
  • the wires 11 and 12 are supported against the supporting structures 14 and 15 , which naturally include openings for receiving water and the fine fibre material removed through the openings of the wires 11 and 12 and removing the same from the gap screen as schematically shown by arrows A.
  • the wires 11 and 12 circulate around rollers 16 and 17 shown by way of example, which as such is known in the art.
  • the sides of the gap 13 at the edges of the wires 11 and 12 are naturally closed, so that the fibre pulp mixture can be fed from a feeding channel 18 to the gap screen appropriately under pressure so as to remove the water and fine fibre material as desired.
  • engines 19 and 20 which are connected to rotate one of the rollers 16 , and 17 respectively, although in a normal situation the engines can be used to circulate each roller separately or a required amount of the rollers in a manner known as such in the art.
  • the engines 19 and 20 are, in turn, connected to a control unit 21 included in the control means that allows to adjust, for example, the rotational speed of the engines so as to make the wires 11 and 12 move at a desired pace, which may deviate from the flowing rate of the fibre pulp through the screen and most preferably exceeds the flowing rate of the fibre pulp mixture.
  • the fibre pulp mixture is fed from the feeding channel 18 to the gap screen, and the mixture thus flows through the gap 13 of the screen and exits from a narrower output port 22 of the gap 13 , i.e. the smaller output port in cross section as regards the feeding opening, from the same side of the screen surfaces or the wires, to which the fibre pulp mixture was originally fed.
  • a narrower output port 22 of the gap 13 i.e. the smaller output port in cross section as regards the feeding opening
  • the speed of motion in the wires can be adjusted in relation to the feeding rate of the fibre pulp mixture fed into the screen until the desired screening result is obtained.
  • the output port 22 refers to the part in the screen, where water and fibres are no longer removed through the wire or wires and the remaining fibre pulp mixture is transferred from the screening phase to the following possible processing phases either directly or controlled by various conveyor means and control means such as wires and the like.
  • one of the wires 11 and 12 can be replaced with a fixed wall surface for example, and a combination can preferably be employed in which the wire 11 moves towards an arched supporting structure 14 and the specific wall surface replaces the wire 12 moving directly within the area of the gap.
  • the adjustment of the screening is mainly based on the fact that the gap screen adjusts the basis weight of the fibre pulp mixture including the long-fibred fibre material that flows through said gap screen.
  • This can be implemented either by adjusting the consistency of the fibre pulp mixture to be fed into the screening or the velocity of the wires in relation to the feeding rate of the fibre pulp mixture.
  • a diluted fibre pulp mixture is fed into the gap screen, more short fibres can be removed from the fibre pulp mixture than if a more consistent fibre pulp mixture is fed under similar circumstances.
  • the velocity of the wires is increased in relation to the feeding rate of the fibre pulp mixture, then more short fibres can correspondingly be removed from the fibre pulp mixture.
  • the separation value of the short fibres can be set at a desired level by adjusting the consistency of the feed and/or the velocity of the wires, so that the result obtained is distinctly different fibre pulp fractions, where the fraction that passes through the wires contains only very short fibres and correspondingly the fraction that flows through the gap of the gap screen contains longer fibres but very few short fibres.
  • the velocity of the wires can be adjusted in various ways, so that it remains below the feeding rate of the fibre pulp, exceeds the feeding rate of the fibre pulp or equals the feeding rate of the fibre pulp. The choice of velocity is based on the properties of the fibre pulp mixture to be screened and on the desired screening result.
  • FIG. 3 schematically shows the result of the screening obtained by means of a gap screen shown in FIG. 1 in accordance with the method of the invention.
  • FIG. 3 shows the screening result, or the portion of the fibres having different freeness values, in the fibre pulp mixture fed and correspondingly in the fraction that passes through the gap and exits through the output end of the gap screen.
  • the portion of the fibres having different freeness values is presented in such a manner that the portion of different fibres in the fibre pulp mixture fed of the entire fibre pulp mixture is indicated by the black column and correspondingly the portion of fibres having a corresponding freeness value included in the fibre pulp fraction that exits through the output end is indicated by the white column.
  • the fibre pulp that has completed the screening shows that the portion of coarse fibres has risen proportionally by nearly 50%, the portion of the following fibres approximately 25%, whereas the portion of the shorter fibres has increased only slightly.
  • the extremely short fibres have, in turn, been removed to a great extent through the wires with the water, and the portion of the short fibres has therefore decreased proportionally by 60%.
  • the extremely short fibre can efficiently be removed from the fibre pulp mixture to be screened and thus obtain a specific fibre pulp fraction that can be used for various purposes by mixing a desired amount thereof to the long fibres for example, in order to manufacture a particular type of fibre web provided with specific properties.
  • the average freeness value of the fibre pulp mixture that passes through the gap screen has increased.
  • FIG. 3 shows that the amount of long fibres in the fraction that passes through the wires is substantially 0 and correspondingly the amount of short fibres in the long-fibred fraction that passes through the gap screen is very low. This indicates that the gap screen operates fairly efficiently and divides the fibre pulp mixture drastically into two fractions of distinctly varying lengths.
  • An appropriate selection of wire structures in the gap screen allows to determine the applicable screening conditions for the fibres of varying lengths in accordance with use and to adjust the efficiency of the screening by controlling the velocity and/or the consistency of the fibre pulp mixture.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Paper (AREA)
  • Separation Of Solids By Using Liquids Or Pneumatic Power (AREA)
  • Preliminary Treatment Of Fibers (AREA)
  • Chemical And Physical Treatments For Wood And The Like (AREA)
US10/414,816 2000-10-16 2003-04-16 Method and apparatus and screen for screening mechanical fiber pulp Abandoned US20040011483A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
FI20002283A FI110619B (fi) 2000-10-16 2000-10-16 Menetelmä ja laitteisto sekä lajitin mekaanisen kuitumassan lajittelemiseksi
FI20002283 2000-10-16
PCT/FI2001/000896 WO2002033165A1 (en) 2000-10-16 2001-10-16 Method and apparatus and screen for screening mechanical fibre pulp

Related Parent Applications (1)

Application Number Title Priority Date Filing Date
PCT/FI2001/000896 Continuation WO2002033165A1 (en) 2000-10-16 2001-10-16 Method and apparatus and screen for screening mechanical fibre pulp

Publications (1)

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US20040011483A1 true US20040011483A1 (en) 2004-01-22

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US10/414,816 Abandoned US20040011483A1 (en) 2000-10-16 2003-04-16 Method and apparatus and screen for screening mechanical fiber pulp

Country Status (14)

Country Link
US (1) US20040011483A1 (zh)
EP (1) EP1334230B1 (zh)
JP (1) JP2004511676A (zh)
CN (1) CN1280477C (zh)
AT (1) ATE338159T1 (zh)
AU (2) AU1059602A (zh)
BR (1) BR0114591A (zh)
CA (1) CA2425511A1 (zh)
DE (1) DE60122766T2 (zh)
ES (1) ES2269473T3 (zh)
FI (1) FI110619B (zh)
NO (1) NO20031662L (zh)
NZ (1) NZ524942A (zh)
WO (1) WO2002033165A1 (zh)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005121447A1 (en) * 2004-06-11 2005-12-22 Imerys Minerals Limited Treatment of pulp
US20120000619A1 (en) * 2009-03-19 2012-01-05 Metso Paper, Inc. Arrangement, system and method for treatment of cellulose pulp
US10041209B1 (en) 2015-08-21 2018-08-07 Pulmac Systems International, Inc. System for engineering fibers to improve paper production
US10941520B2 (en) 2015-08-21 2021-03-09 Pulmac Systems International, Inc. Fractionating and refining system for engineering fibers to improve paper production
US11214925B2 (en) 2015-08-21 2022-01-04 Pulmac Systems International, Inc. Method of preparing recycled cellulosic fibers to improve paper production

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2995325B1 (fr) * 2012-09-11 2015-03-13 Ct Tech De L Ind Des Papiers Cartons Et Celluloses Procede de fabrication d'un support fibreux multicouche par fractionnement et stratification
CN115418878A (zh) * 2022-08-17 2022-12-02 中集竹链科技有限公司 物料筛分系统及筛分方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5228954A (en) * 1991-05-28 1993-07-20 The Procter & Gamble Cellulose Company Cellulose pulps of selected morphology for improved paper strength potential
US5582685A (en) * 1993-06-24 1996-12-10 The Procter & Gamble Company Method for producing a cellulose pulp of selected fiber length and coarseness by a two-stage fractionation
US5916417A (en) * 1997-08-22 1999-06-29 International Paper Company Method of making multi-ply paperboard sheet having layers of different fiber properties

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0958430A1 (en) * 1996-02-28 1999-11-24 Alfa Laval AB Improved recovery of fine fibers from suspensions containing fibers and contaminants
FI108152B (fi) * 1999-07-22 2001-11-30 Metso Paper Inc Menetelmä ja laitteisto kuitumassaseoksen pesemiseksi

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5228954A (en) * 1991-05-28 1993-07-20 The Procter & Gamble Cellulose Company Cellulose pulps of selected morphology for improved paper strength potential
US5582685A (en) * 1993-06-24 1996-12-10 The Procter & Gamble Company Method for producing a cellulose pulp of selected fiber length and coarseness by a two-stage fractionation
US5916417A (en) * 1997-08-22 1999-06-29 International Paper Company Method of making multi-ply paperboard sheet having layers of different fiber properties

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005121447A1 (en) * 2004-06-11 2005-12-22 Imerys Minerals Limited Treatment of pulp
US20080264586A1 (en) * 2004-06-11 2008-10-30 Mikko Henrik Likitalo Treatment of Pulp
US20120000619A1 (en) * 2009-03-19 2012-01-05 Metso Paper, Inc. Arrangement, system and method for treatment of cellulose pulp
US8303769B2 (en) * 2009-03-19 2012-11-06 Metso Paper, Inc. Arrangement, system and method for treatment of cellulose pulp
US10041209B1 (en) 2015-08-21 2018-08-07 Pulmac Systems International, Inc. System for engineering fibers to improve paper production
US10400394B2 (en) 2015-08-21 2019-09-03 Pulmac Systems International, Inc. Method for engineering fibers to improve paper production
US10941520B2 (en) 2015-08-21 2021-03-09 Pulmac Systems International, Inc. Fractionating and refining system for engineering fibers to improve paper production
US11214925B2 (en) 2015-08-21 2022-01-04 Pulmac Systems International, Inc. Method of preparing recycled cellulosic fibers to improve paper production

Also Published As

Publication number Publication date
DE60122766T2 (de) 2007-08-30
WO2002033165A1 (en) 2002-04-25
NO20031662D0 (no) 2003-04-10
AU1059602A (en) 2002-04-29
AU2002210596B2 (en) 2006-05-18
FI20002283A0 (fi) 2000-10-16
EP1334230B1 (en) 2006-08-30
FI20002283A (fi) 2002-04-17
BR0114591A (pt) 2003-10-14
JP2004511676A (ja) 2004-04-15
CN1280477C (zh) 2006-10-18
CN1553979A (zh) 2004-12-08
ES2269473T3 (es) 2007-04-01
DE60122766D1 (de) 2006-10-12
CA2425511A1 (en) 2002-04-25
NO20031662L (no) 2003-04-10
ATE338159T1 (de) 2006-09-15
EP1334230A1 (en) 2003-08-13
NZ524942A (en) 2004-12-24
AU2002210596C1 (en) 2006-09-28
FI110619B (fi) 2003-02-28

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AS Assignment

Owner name: METSO PAPER INC., FINLAND

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:HAUTALA, JOUKO;JUUTINEN, VESA;NIEMINEN, ERKKA;REEL/FRAME:013905/0610

Effective date: 20030811

STCB Information on status: application discontinuation

Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION

AS Assignment

Owner name: VALMET TECHNOLOGIES, INC., FINLAND

Free format text: CHANGE OF NAME;ASSIGNOR:METSO PAPER, INC.;REEL/FRAME:032551/0426

Effective date: 20131212