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WO2005003448A1 - Procede et laveuse pour le lavage et l'essorage de fibres en suspension - Google Patents

Procede et laveuse pour le lavage et l'essorage de fibres en suspension Download PDF

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Publication number
WO2005003448A1
WO2005003448A1 PCT/SE2004/001045 SE2004001045W WO2005003448A1 WO 2005003448 A1 WO2005003448 A1 WO 2005003448A1 SE 2004001045 W SE2004001045 W SE 2004001045W WO 2005003448 A1 WO2005003448 A1 WO 2005003448A1
Authority
WO
WIPO (PCT)
Prior art keywords
press
fibre
wash
fibre web
roll
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/SE2004/001045
Other languages
English (en)
Inventor
Jörgen Lundberg
Rickard Andersson
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
Publication of WO2005003448A1 publication Critical patent/WO2005003448A1/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
    • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
    • D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
    • D21C9/02—Washing ; Displacing cooking or pulp-treating liquors contained in the pulp by fluids, e.g. wash water or other pulp-treating agents
    • D21C9/06—Washing ; Displacing cooking or pulp-treating liquors contained in the pulp by fluids, e.g. wash water or other pulp-treating agents in filters ; Washing of concentrated pulp, e.g. pulp mats, on filtering surfaces
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
    • D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
    • D21C9/18—De-watering; Elimination of cooking or pulp-treating liquors from the pulp

Definitions

  • the present invention relates to a method and an apparatus at dewatering of a fibre suspension and a wash press for carrying out the method.
  • washing of fibre suspensions, such as pulp is an important process in inter alia chemical pulp production, where the purpose with the washing is to purify the pulp form cooking liquid and make use of the chemicals of the cooking liquid for recovery. If the washing is not sufficiently effective, problems will arise in the operation after the wash, such as high chemical consumption in the bleachery, contaminated mill discharges and foaming. Furthermore, an ineffective washing results in a deteriorated economy regarding the chemical recovery, since valuable cooking liquid chemicals will be lost. The efficiency of the washing is therefore of great importance for the whole economy of the pulp production.
  • washing apparatuses for washing of fibre suspensions at pulp production is inter alia wash diffusers, wash filters of different kind, wash wires and wash presses.
  • washing with wash presses also a major part of the liquid that is bound in the fibres in the fibre suspension is squeezed due to the high pressure that is applied, which is an advantage compared to other washing methods.
  • State of the art at use of wash presses is that the pulp is pressed to a high pulp consistency, usually between 20-50%, in the respective wash press. Between the wash presses the pulp is diluted, usually to a pulp consistency below 10%, by adding wash liquid that is forced into the pulp during mixing with the pulp in a mixing screw.
  • the present invention aims to achieve a more effective and improved washing by a combination of displacement and dewatering of a fibre suspension compared to prior art.
  • This object is obtained with the method for washing and dewatering of a fibre suspension according to the present invention, comprising the steps: a) dewatering the fibre suspension such that a continuous fibre web is formed, b) dewatering the fibre web further to a fibre concentration in the range of about 20% to about 40%, c) adding wash liquid subsequently to the fibre web such that the fibre web is allowed to swell with a continuously increasing volume during absorption of at least a part of the wash liquid and without essentially any dewatering by displacement of liquid in the fibre web, and d) dewatering the fibre web again with added wash liquid to a fibre concentration in the range of about 20% to about 40%.
  • the method facilitates that the number of wash apparatuses/presses can be reduced, which results in that washing and thereto also the pulp production operation economy can be considerably improved. Approximately, the method facilitates that only two wash apparatuses in accordance with the present invention can provide the desired wash result, compared to where it traditionally requires three washing apparatuses.
  • An important principle according to the present invention is that the wash liquid is added to the pulp at high concentration such that a favourable wash ratio is obtained simultaneous as the output pulp concentration can be kept high.
  • the wash liquid addition is too small in comparison to the filtrate content in the pulp since the pulp concentration at wash liquid addition is low, usually between 8-15%.
  • the wash liquid addition becomes larger in comparison to the filtrate content, i.e. an improved wash ratio is obtained.
  • the high concentration implies that no dewatering is carried out by displacement in the dilution zone, on the contrary the fibre web is allowed to swell with continuously increasing volume .
  • wash liquid in this description is meant liquid that is more pure than the liquid that is in the fibre suspension.
  • dilution zone in this description is meant the space between two pressure nips where addition of wash liquid is made. No dewatering by displacement of liquid in the fibre web takes place in the dilution zone.
  • Said "dewatering" according to the present method can be achieved in a number of ways, inter alia as is evident in the following description with rolls and press nips.
  • the dewatering can for example also be achieved by using vacuum chambers on a flat wire.
  • the fibre suspension is distributed on a flat wire and is allowed to pass vacuum chambers in step b) and d) where the dewatering to concentration range about 20% to about 40% is done.
  • the wash liquid is added between these steps such that the fibre web is allowed to swell during absorption of at least a part of the wash liquid.
  • a concentration gradient of contaminations occurring in the fibre web is achieved, such as cooking liquid.
  • the wash liquid that applied to the fibre web in step c) exceeds preferably a amount of liquid that remains in the fibre web after the dewatering in step b) .
  • the present invention also relates to a wash press for carrying out the method, for dewatering of a fibre suspension, which wash press comprises a liquid permeable rotating main roll on which periphery the fibre suspension is fed, forming a continuous fibre web.
  • a first press roll forms with the main roll a first press nip for dewatering of the fibre web.
  • the wash press comprises a second press roll that forms a second press nip with the main roll for dewatering of the fibre web.
  • a trough, that extends between the first and second press nips, defines a dilution zone where the fibre web is allowed to swell.
  • Supply elements is arranged to add wash liquid to the fibre web in the dilution zone. The dilution zone diverges in the direction from the first press nip to the second press nip.
  • fig. 1 schematically shows a wash press for carrying out the method of the present invention
  • fig. 2 shows outlined an embodiment of the wash press according to fig. 1
  • fig. 3A-D illustrates alternative embodiments of the wash press
  • fig. 4 schematically shows additionally one alternative embodiment of the wash press.
  • Fig. 1 shows a wash press 2 for carrying out the method of the present invention, for dewatering of a fibre suspension (not shown) .
  • the wash press 2 comprises a liquid permeable rotating main roll 4 on which periphery 6 the fibre suspension is fed, by applying the fibre suspension on the main roll at an inlet zone 7, for forming a continuous fibre web (not shown) on the main roll.
  • a first rotating press roll 8 forms with the main roll 4 a first press nip 10 for dewatering of the fibre web. Displacement of liquid occurs essentially through the liquid permeable surface of the main roll, such as a perforated casing surface, into the main roll in a way known by the person skilled in the art (see arrows 11) .
  • the washing press 2 comprises a second rotating press roll 12 that forms a second press nip 14 with the main roll 4 for dewatering (see arrows 11) of the fibre web.
  • a trough 16, that extends between the first and second press nips 10, 14, define a dilution zone 18 where the fibre web is allowed to swell.
  • the output fibre web is removed, teared and diluted with a doctor/shredder screw 20 with dilution.
  • the first press roll 8 in the first press nip 10 can be a liquid permeable roll.
  • the first press roll 8 is a smooth roll.
  • the second press roll 12 in the second press nip 14 is suitably a smooth roll. The use of preferably smooth rolls guarantees that dewatering of wash liquid only occurs in a direction in towards the liquid permeable main roll 4.
  • the trough 16 can be arranged such that the dilution zone 18 defines a continuous cross section for the fibre web from the first 10 to the second press nip 14.
  • the through 16 is arranged such that the dilution zone 18 diverge in the direction from the first press nip to the second press nip 14, which allows a continuous increasing, diverging cross section of the fibre web along the dilution zone 18.
  • the fibre web is allowed to swell with a continuously increasing volume during absorption of wash liquid in the dilution zone 18, without essentially any displacement of wash liquid.
  • Fig. 2 shows an embodiment of the wash press of fig. 1, which illustrates supply elements 22 arranged to add wash liquid to the fibre web in the dilution zone 18.
  • Said supply elements 22 for to adding wash liquid is arranged on one side of the fibre web, suitably on the outer side 23 of the fibre web in relation to the main roll 4, at the trough 16 and suitably arranged on the outside 24 of the trough opposite the fibre web.
  • Said supply elements 22 are arranged to add wash liquid in direction against the main roll 4, at the outside of the fibre web.
  • the wash liquid can form a layer on the outside of the fibre web that completely or partly is absorbed by the fibre web in the dilution zone 18 before the second press nip 14. Thanks to at least a partly absorption of wash liquid of the fibre web, a concentration gradient of contaminations is achieved in the fibre web where the degree of contamination in the fibre web increases in direction against the main roll 4.
  • the second press roll 12 in the second press nip 14 is suitably a smooth roll.
  • Fig. 2 also shows liquid supply elements 26 arranged at the inlet zone 7 for wetting ("lubrication") of the contact surface between the fibre web and a wall section 28 of the inlet zone 7, which facilitates the feeding in the first press nip.
  • Figs. 3A-D illustrates alternative embodiments ((that in principal corresponds to embodiments in fig. 1) of the wash press 2 according to present invention, in which figs, the length LI of the inlet zone respective the length L2 of the dilution zone are varied.
  • the length L2 of the dilution zone is adapted such that a sufficient absorption and swelling of the fibre web can be guaranteed.
  • Fig. 3A shows an embodiment where the inlet zone LI for the feeding on of the fibre suspension on the main roll 4 extends along less than 1/4 of the circumference of the main roll 4 and where the dilution zone L2 extends along about 3/4 of the circumference of the main roll 4.
  • FIG. 3B shows additionally an embodiment where the inlet zone LI extends along 1/4 of the circumference of the main roll 4 and where the dilution zone L2 extends along about 1/2 of the circumference of the main roll 4.
  • Fig. 3C shows a similar extension of inlet zone Ll and dilution zone L2, respectively, as in fig. 3B, but where doctor 20' and shredder screw 20' ' , respectively, have an alternative placement.
  • Fig. 3D shows a similar extension of inlet zone Ll and dilution zone L2, respectively, as in fig. 3A, but where doctor 20' and shredder screw 20'', respectively, have an alternative placement.
  • the dilution zone 18 has a length L2 that extends between 1/4 and 3/4 of the circumference of the main roll 4.
  • the length L2 of the dilution zone 18 extends along about 1/2 of the circumference of the main roll 4.
  • the inlet zone 7 for the feeding on of the fibre suspension on the main roll has a length Ll that suitably extends less than about 3/4 of the circumference of the main roll 4 and preferably less than about 1/2 of the circumference of the main roll 4.
  • the method for washing and dewatering of a fibre suspension in a wash press 2 is as follows:
  • the fibre suspension is fed on a periphery 6 of a liquid permeable rotating main roll 4, such that the fibre suspension is dewatered and forms a continuous fibre web.
  • the fibre concentration of the fibre suspension can be about 3-8% and can suitably be increased to at least 10% at the feeding on the main roll.
  • the fibre web is dewatered additionally in a first press nip 10 formed by a first press roll 8 and the main roll 4, to a fibre concentration in the range of about 20% to about 40%, and preferably in the range about 22% to about 28%.
  • Wash liquid is applied to the fibre web after the first press nip 10, such that the fibre web is allowed to swell with a continuously increasing volume during absorption of at least a part of the wash liquid and without essentially any dewatering by displacement of liquid in the fibre web.
  • the fibre web in the dilution zone is allowed to absorb wash liquid and swell such that the fibre concentration of the fibre web is in the range of about 8% to about 17%, and preferably in the range 9-13%.
  • the fibre web with added wash liquid is dewatered in a second press nip 14 formed by a second press roll 12 and the main roll 4 such that the fibre concentration is in the range of about 20% to about 40%, and preferably in the range about 22% to about 28%.
  • Fig. 4 shows schematically yet an alternative embodiment of the wash press 2 according to the present invention.
  • the second press roll according to this embodiment is composed of a second liquid permeable main roll 4', which above mentioned main roll 4 (see description with reference to figs. 1-3), in the following named first main roll 4, together with the second main roll 4' forms the second press nip 14.
  • This embodiment makes it possible, simultaneously as a fibre suspension is dewatered on the first main roll 4, to also apply a second fibre suspension for dewatering to form a second fibre web on the second main roll 4' in corresponding way as described above with reference to figs. 1-3.
  • a second fibre suspension is fed on at the second main roll 4' via an inlet zone 7' .
  • the second main roll forms a first press nip 10' with a third press roll 30 at the second main roll 4', through which press nip the second fibre web is conveyed, whereupon wash liquid is applied to the second fibre web in a second dilution zone 18', defined by a second trough 16' that extends between the first 10' and second press nip 14 (in corresponding way as described above with reference to figs. 1-3) at the second main roll 4'.
  • the fibre webs, respectively are brought together, side by side, whereupon dewatering of the fibre web brought together simultaneous is done in two opposite directions (see arrows 11' ) , in a direction in against the first 4 respectively the second main roll 4' .

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Wood Science & Technology (AREA)
  • Paper (AREA)
  • Treatment Of Fiber Materials (AREA)

Abstract

La présente invention concerne un procédé de lavage et d'essorage de fibres en suspension. Ce procédé comporte plusieurs opérations: essorage des fibres en suspension de façon à former une bande continue de fibres; continuer l'essorage jusqu'à une concentration en fibres comprise entre environ 20 % et environ 40 %; adjonction à la bande de fibres d'un liquide de lavage de façon à la faire gonfler d'un volume augmentant en continu pendant l'absorption d'au moins une partie du liquide de lavage, et sensiblement sans essorage par déplacement de liquide dans la bande de fibres; enfin, nouvel essorage de la bande de fibres avec le liquide de lavage ajouté jusqu'à une concentration en fibres entre environ 20 % et environ 40 %. L'invention concerne également une laveuse permettant la mise en oeuvre du procédé.
PCT/SE2004/001045 2003-07-01 2004-06-28 Procede et laveuse pour le lavage et l'essorage de fibres en suspension Ceased WO2005003448A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE0301941A SE525565C2 (sv) 2003-07-01 2003-07-01 Förfarande och tvättpress för tvättning och avvattning av en fibersuspension
SE0301941-1 2003-07-01

Publications (1)

Publication Number Publication Date
WO2005003448A1 true WO2005003448A1 (fr) 2005-01-13

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE2004/001045 Ceased WO2005003448A1 (fr) 2003-07-01 2004-06-28 Procede et laveuse pour le lavage et l'essorage de fibres en suspension

Country Status (2)

Country Link
SE (1) SE525565C2 (fr)
WO (1) WO2005003448A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2079872A4 (fr) * 2006-10-27 2012-07-04 Metso Paper Inc Presse de lavage à séparation de filtrats
US8828189B2 (en) 2012-01-30 2014-09-09 Andritz Inc. Washer press with multiple nips and multiple displacement wash zones
WO2019061010A1 (fr) * 2017-09-26 2019-04-04 深圳德为智造科技有限公司 Dispositif de lavage de pâte a papier
WO2019062764A1 (fr) * 2017-09-26 2019-04-04 深圳德为纤维环保科技有限公司 Machine à laver ou à broyer la pâte à papier perfectionnée

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3564631A (en) * 1968-05-16 1971-02-23 Improved Machinery Inc Pulp treating apparatus and method
US4481118A (en) * 1982-03-01 1984-11-06 Maschinenfabrik Andritz Actiengesellschaft Method and apparatus for rinsing filter cake
WO1997013026A1 (fr) * 1995-10-02 1997-04-10 Alfa Laval Celleco Ab Appareil d'essorage, de pressurage et de lavage de la pate a papier
US5901585A (en) * 1995-06-12 1999-05-11 Kvaerner Pulping Ab Drum supported by support rollers for washing fibre material

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3564631A (en) * 1968-05-16 1971-02-23 Improved Machinery Inc Pulp treating apparatus and method
US4481118A (en) * 1982-03-01 1984-11-06 Maschinenfabrik Andritz Actiengesellschaft Method and apparatus for rinsing filter cake
US5901585A (en) * 1995-06-12 1999-05-11 Kvaerner Pulping Ab Drum supported by support rollers for washing fibre material
WO1997013026A1 (fr) * 1995-10-02 1997-04-10 Alfa Laval Celleco Ab Appareil d'essorage, de pressurage et de lavage de la pate a papier

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
SANDBERG U. ET AL.: "Tvattning av massa", SKOGSINDUSTRINS UTBILDNING I MARKARYD AB, 1994, pages 13-14,46 *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2079872A4 (fr) * 2006-10-27 2012-07-04 Metso Paper Inc Presse de lavage à séparation de filtrats
US8828189B2 (en) 2012-01-30 2014-09-09 Andritz Inc. Washer press with multiple nips and multiple displacement wash zones
US8926795B2 (en) 2012-01-30 2015-01-06 Andritz Inc. Method for using washer press with multiple nips and multiple displacement wash zones
WO2019061010A1 (fr) * 2017-09-26 2019-04-04 深圳德为智造科技有限公司 Dispositif de lavage de pâte a papier
WO2019062764A1 (fr) * 2017-09-26 2019-04-04 深圳德为纤维环保科技有限公司 Machine à laver ou à broyer la pâte à papier perfectionnée

Also Published As

Publication number Publication date
SE0301941L (sv) 2005-01-02
SE525565C2 (sv) 2005-03-08
SE0301941D0 (sv) 2003-07-01

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