[go: up one dir, main page]

WO1996017996A1 - Lavage de la pate a papier dans un systeme de lavage avec fractionnement - Google Patents

Lavage de la pate a papier dans un systeme de lavage avec fractionnement Download PDF

Info

Publication number
WO1996017996A1
WO1996017996A1 PCT/FI1995/000668 FI9500668W WO9617996A1 WO 1996017996 A1 WO1996017996 A1 WO 1996017996A1 FI 9500668 W FI9500668 W FI 9500668W WO 9617996 A1 WO9617996 A1 WO 9617996A1
Authority
WO
WIPO (PCT)
Prior art keywords
washing
pulp
stage
stages
filtrate
Prior art date
Application number
PCT/FI1995/000668
Other languages
English (en)
Inventor
Kari Ala-Kaila
Kaj Henricson
Pekka Tervola
Original Assignee
Ahlstrom Machinery 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 Ahlstrom Machinery Oy filed Critical Ahlstrom Machinery Oy
Publication of WO1996017996A1 publication Critical patent/WO1996017996A1/fr

Links

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
    • D21D1/20—Methods of refining
    • D21D1/40—Washing the fibres
    • 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
    • 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
    • D21C9/04—Washing ; Displacing cooking or pulp-treating liquors contained in the pulp by fluids, e.g. wash water or other pulp-treating agents in diffusers ; Washing of pulp of fluid consistency without substantially thickening

Definitions

  • the present invention relates to a method of Intensifying washing, especially in connection with oxygen delignification.
  • the invention especially relates to the utilization of fractionating wash in connection with oxygen delignification.
  • Fractionating wash generally means that the filtrate is discharged from a washing stage at least in two fractions having different dry-solids contents.
  • the filtrate divided in this way may be used in a suitable way in previous washing stages.
  • the theory of fractionating wash has been described in a publication "A mathematical model of fractional pulp washing and applications in a bleach plant" by Tervola, Henricson, Gullichsen; Tappi Pulping
  • CONFIRMA ⁇ ON COPY washing system so as to take advantage of both the benefits provided by the fractionating washing arrangement and the influence of the displacement time reduces the washing loss further by 20 - 30 %.
  • washing loss describes in pulp production the volume of dry-solids ending up from the fibers to the effluent treatment. In other words, the reduction of the washing loss by 20 - 30 % results in a similar percentage in the reduction of environmental stress.
  • a suitable thickness is 70 - 400 mm, preferably 100 - 250 mm.
  • Apparatus having conventionally this kind of pulp layer thicknesses are e.g. a continuous atmospheric diffuser employing a pulp layer thickness of 200 - 250 mm, and a pressure diffuser having a pulp layer thickness of 80 - 150 nun.
  • the invention may thus be well applied to these washers but also to other washer types having an adequate pulp layer thickness. It should be noted that the above mentioned article discussing fractionating wash does not mention the use of extraction. An obvious reason for this is that the thickness of the pulp layer in a DRUM DISPLACER* washer is approx. 40 - 50 mm, which does not give a treatment time long enough for extracting dry-solids from the fibers.
  • a characteristic feature of the method of the invention is that the pulp layer to be washed is arranged thick enough for the extraction process.
  • a characteristic feature of a preferred embodiment of the invention is that a) oxygen bleached pulp is conveyed to a washing system comprising at least two washing stages, at least two stages in the system having been divided into two zones; b) pulp is washed in the first stage of said system by supplying different washing liquids to the zones of said stage and by extracting dry-solids from the pulp; c) two washing filtrates are separated from the zones of said first stage; d) pulp is washed in the second stage of said system by supplying washing liquids to the zones of said second stage and by extracting dry-solids from the pulp; e) two washing filtrates are separated from the zones of said second stage, the filtrates being supplied as the washing liquids to stage b) ; and f) the pulp is discharged from the washing system.
  • Fig. 1 illustrates schematically the method of the invention applied to an atmospheric diffuser
  • Fig. 2 illustrates schematically the method of the invention applied to a wash following an oxygen delignification process
  • Fig. 5 illustrates a preferred way of using the fractionating diffuser of the invention.
  • Fig. 1 illustrates an atmospheric diffuser 10, including two exemplary washing stages 12 and 22.
  • the pulp to be washed is supplied to the bottom of the diffuser 10 via a conduit 14 and the washed pulp is discharged via a conduit 16 from the top of the vessel.
  • the pulp When flowing upwards in the vessel the pulp is subjected to the first washing stage 12 and after that to the second washing stage 22; subsequently the washed pulp flows to the discharge conduit 16.
  • Washing water is supplied via conduit l ⁇ at the top of the vessel to the second washing stage 22 from which at least two filtrates, SI and S2, are obtained by so-called fractionation, by dividing the washing stage into at least two zones 221 and 222, of which filtrates S2 is the first one (with regard to the flow direction of the pulp) and thus the more contaminated one while washing the more contaminated pulp.
  • the filtrates SI and S2 are taken to the first washing stage 12 as washing liquids so that the more contaminated first (in the flow direction of the pulp) washing liquid S2 is used in the first washing zone 121 and the cleaner washing liquid SI is used in the second washing zone 122.
  • Two "fresh" filtrates, S3 and S4 are obtained from the washing zones 121 and 122.
  • the filtrates are conveyed from one washing stage to another by using the technical solutions disclosed in EP patent applications 92890090 and 92890253, where applicable.
  • pulp is prewashed in a washer 30, which preferably is a filter washer giving a discharged consistency of 10 - 18 %. After this the content of organic material dissolved from the fibers in the pulp is 140 - 160 kg/ton expressed as COD, preferably 100 - 80 kg COD/ton.
  • a washing system in Fig.
  • FIG. 2 an exemplary washing device similar to the one illustrated in Fig. 1 by reference number 10) comprising at least two washing stages utilizing f actionating wash and having a thickness of the pulp layer to be washed of 70 - 400 mm in order to ensure an adequate extraction time.
  • the washing system comprises a two-stage (12, 22) diffuser 10; naturally also a diffuser comprising more stages, or some other washing system meeting the basic requirements may be used.
  • the filtrate connections of the diffuser 10 are similar to the ones in Fig. 1.
  • the washing loss after a washing system described above is 7 - 4 kg COD/ton whereas with conventional methods it would have been 10 - 6 kg COD/ton of pulp.
  • fractionating wash is employed also in the washer 30 preceding the oxygen stage, which further improves the result.
  • a thickener or a press 40 is provided after the diffuser 10 to increase the consistency to a range of 12 - 35 %, preferably to 15 - 25 %. This is done because, since the washer 10 treats a thick layer of pulp, the discharge consistency is low, i.e. 8 - 12 %, which is often too low for the final bleaching.
  • An advantageous temperature is 70 - 120°C, preferably 80 - 100°C.
  • the clean washing liquid W is directed to serve as the washing liquid in the second zone 222 of the washing stage 22.
  • the filtrate F which has been separated in the thickener 40 from the washed pulp having been discharged from the two- or multi-stage diffuser 10 following the oxygen stage, is used at least as a part of the washing liquid supplied to the first zone 221 of the second washing stage 22, while the rest of the liquid to the zone 221 may optionally but not necessarily be for example clean washing liquid W, as illustrated in the figure by a broken line.
  • the two different filtrates SI and S2 obtained from the washing stage 22 are directed to the first washing stage 12 so that the cleaner filtrate SI flows to serve as the washing liquid in the second zone 122 of the first stage 12, and the more contaminated filtrate S2 to serve as the washing liquid in the first zone 121 of the washing stage 12.
  • Separate filtrates, S3 which is the cleaner filtrate, and S4 which is the more contaminated one are discharged from both the zones of the first washing stage 12, and conveyed to the washer 30 preceding the oxygen stage 32 to serve as the washing liquids.
  • the washer 30 is preferably a multi-stage filter-type washer, the filtrates/washing liquids produced by fractionation may be used also in this washer to wash the pulp to be supplied to the oxygen stage cleaner.
  • FIG. 3 a horizontal and schematical cross-section of a conventional diffuser structure is shown.
  • the diffuser 50 normally consists of a series of screen rings 52, 54 and 56 connected to arms 58.
  • the washing liquid is introduced into the pulp from the top of the diffuser as shown in Fig 1.
  • the washing liquid flows downwardly and flows further as a filtrate through the filter surfaces into the interior screen rings 52, 54, 56 and to the arms 58 via which it is, then, taken out of the system.
  • Figs. 4a and b illustrate a diffuser screen package in accordance with a preferred embodiment of the invention.
  • the diffuser screen package 60 consisting of only one screen ring 62 is shown.
  • a diffuser screen packace includes a number of coaxially arranged screen rings.
  • the screen package 60 can be constructed for fractionating the filtrate flow by means of arranging a horizontal intermediate wall 64 into the interior volume of the screen ring 62 and fastened to the opposite filter surfaces 66 and 68.
  • the intermediate wall 64 divides, preferably, the interior volume of the screen ring 62 into two equal volumes 70 and 72.
  • softwoo total loss was reduced by 17 %, concentration in free liquid around fibers was reduced by about 29 %; hardwood: total loss was reduced by 10 %, and concentration in free liquid around fibers was reduced by about 23 %.
  • the thickness of the fiber mat in the diffuser was 250 mm.
  • the temperature was 90°C.
  • Another way of using a fractionating diffuser 80 is its use in brown stock washing after a digester 82 (Fig. 5).
  • the operational efficiency of the digester-diffuser combination may be improved by 10 - 20 % by taking the cleaner fraction 84 from the diffuser 80 to the bottom of the digester 82 and the more contaminated fraction 86 to a circulation in the digester 82, preferably to the wash circulation or the lowest circulation in the digester 82.
  • the thickness of the fiber mat is 200 - 300 mm, the temperature being high, about 95°C.
  • Figure 5 shows yet another preferred embodiment of the present invention a system called "Extended cold blow system" for improving the washing performance.
  • Strong wash liquid 86 is taken via a central pipe 88 to a point above the bottom of the digester 82.
  • Weaker wash liquid 84 from the fractionating diffuser 80 is taken, possibly after cooling 90, to the bottom of the digester.
  • Two liquids, 92 and 94 are extracted from the digester 82; namely, a strong liquid 92, strong in OH and S, suitable for chip pretreatment, and a weak liquid 94 for other purposes, like for example to evaporation or liquid fill.
  • a strong liquid 92, strong in OH and S suitable for chip pretreatment
  • a weak liquid 94 for other purposes, like for example to evaporation or liquid fill.
  • the pulp thickness in the diffuser is 250 mm and in the digester bottom section 3 - 5 meters.
  • the temperature in the diffuser is 95°C and in the digester bottom section 100 - 150°C.

Landscapes

  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Wood Science & Technology (AREA)
  • Paper (AREA)

Abstract

Cette invention se rapporte à un procédé qui permet d'intensifier le lavage de la pâte à papier, en particulier en relation avec une opération de délignification à l'oxygène. Cette invention se rapporte plus particulièrement à l'utilisation d'une technique de lavage avec fractionnement dans l'opération de délignification à l'oxygène. A cet effet, la pâte à papier est lavée dans au moins deux phases de lavage à déplacement avec fractionnement (12, 22). Deux fractions de filtrat différentes (S1, S2) sont retirées de la seconde phase de lavage. Ces filtrats sont utilisés comme liquides de lavage dans la première phase de lavage (12). La température dans le système de lavage est maintenue au-dessus de 90 °C et l'épaisseur de la couche de pâte à laver est supérieure à 70 mm.
PCT/FI1995/000668 1994-12-08 1995-12-05 Lavage de la pate a papier dans un systeme de lavage avec fractionnement WO1996017996A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI945783 1994-12-08
FI945783A FI945783L (fi) 1994-12-08 1994-12-08 Menetelmä pesun tehostamiseksi

Publications (1)

Publication Number Publication Date
WO1996017996A1 true WO1996017996A1 (fr) 1996-06-13

Family

ID=8541944

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/FI1995/000668 WO1996017996A1 (fr) 1994-12-08 1995-12-05 Lavage de la pate a papier dans un systeme de lavage avec fractionnement

Country Status (2)

Country Link
FI (1) FI945783L (fr)
WO (1) WO1996017996A1 (fr)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001009432A1 (fr) * 1999-07-21 2001-02-08 Metso Chemical Pulping Oy Procede et installation de lavage de pate
WO2002033164A3 (fr) * 2000-10-17 2002-07-04 James Hardie Res Pty Ltd Procede et appareil permettant de reduire les impuretes presentes dans des fibres de cellulose destinees a la fabrication de materiaux composites de ciment renforce de fibres
EP1574614A2 (fr) 2000-10-17 2005-09-14 James Hardie International Finance B.V. Procédé pour réduire des impuretés dans des fibres cellulosiques pour la production des matériaux de ciment composites renforcés par des fibres
US7344593B2 (en) 2001-03-09 2008-03-18 James Hardie International Finance B.V. Fiber reinforced cement composite materials using chemically treated fibers with improved dispersibility
EP1435409A3 (fr) * 2002-12-26 2008-10-08 Weyerhaeuser Company Pâte à papier non blanchie à très faible demande chimique en oxygène
EP2473670A4 (fr) * 2009-09-01 2014-01-08 Andritz Oy Procédé et ensemble pour le traitement de pâte cellulosique issue de l'industrie de transformation du bois
US8993462B2 (en) 2006-04-12 2015-03-31 James Hardie Technology Limited Surface sealed reinforced building element
US20210040688A1 (en) * 2018-03-07 2021-02-11 Andritz Oy Method of producing dissolving pulp
US20240167224A1 (en) * 2021-03-25 2024-05-23 Matias TITOFF Method and apparatus for treating mixtures of liquids and solids

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4971658A (en) * 1986-12-17 1990-11-20 A. Ahlstrom Corporation Method of intensifying the washing of a fiber suspension
EP0509981A1 (fr) * 1991-04-16 1992-10-21 Kamyr, Inc. Diffuseur sous pression à deux étapes

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4971658A (en) * 1986-12-17 1990-11-20 A. Ahlstrom Corporation Method of intensifying the washing of a fiber suspension
EP0509981A1 (fr) * 1991-04-16 1992-10-21 Kamyr, Inc. Diffuseur sous pression à deux étapes

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
TAPPI PULPING CONFERENCE, Book 1, 1993, Atlanta, Georgia, TAPPI PRESS, P. TERVOLA et al., "A Mathematical Model of Fractional Pulp Washing and Applications in a Bleach Plant", pages 151-154. *
TVATTNING AV MASSA, Y-206 1- 2000.1974-07, ISBN 91-7322-014-0, SVERIGES SKOGSINDUSTRIFORBUND, 1974, pages 10, 26, 30, 32, 33. *

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001009432A1 (fr) * 1999-07-21 2001-02-08 Metso Chemical Pulping Oy Procede et installation de lavage de pate
CN100535239C (zh) * 2000-10-17 2009-09-02 詹姆斯哈迪国际财金公司 减少用于制造纤维强化水泥复合材料的纤维素纤维的杂质的制造方法
EP1574614A2 (fr) 2000-10-17 2005-09-14 James Hardie International Finance B.V. Procédé pour réduire des impuretés dans des fibres cellulosiques pour la production des matériaux de ciment composites renforcés par des fibres
EP1574614A3 (fr) * 2000-10-17 2005-11-16 James Hardie International Finance B.V. Procédé pour réduire des impuretés dans des fibres cellulosiques pour la production des matériaux de ciment composites renforcés par des fibres
WO2002033164A3 (fr) * 2000-10-17 2002-07-04 James Hardie Res Pty Ltd Procede et appareil permettant de reduire les impuretes presentes dans des fibres de cellulose destinees a la fabrication de materiaux composites de ciment renforce de fibres
US7344593B2 (en) 2001-03-09 2008-03-18 James Hardie International Finance B.V. Fiber reinforced cement composite materials using chemically treated fibers with improved dispersibility
EP1435409A3 (fr) * 2002-12-26 2008-10-08 Weyerhaeuser Company Pâte à papier non blanchie à très faible demande chimique en oxygène
US8993462B2 (en) 2006-04-12 2015-03-31 James Hardie Technology Limited Surface sealed reinforced building element
EP2473670A4 (fr) * 2009-09-01 2014-01-08 Andritz Oy Procédé et ensemble pour le traitement de pâte cellulosique issue de l'industrie de transformation du bois
US9163358B2 (en) 2009-09-01 2015-10-20 Andritz Oy Method and assembly for processing cellulose pulp of wood processing industry
EP3249098A1 (fr) * 2009-09-01 2017-11-29 Andritz Oy Procédé et ensemble de traitement de la pulpe de cellulose dans l'industrie de transformation du bois
US20210040688A1 (en) * 2018-03-07 2021-02-11 Andritz Oy Method of producing dissolving pulp
US20240167224A1 (en) * 2021-03-25 2024-05-23 Matias TITOFF Method and apparatus for treating mixtures of liquids and solids

Also Published As

Publication number Publication date
FI945783A7 (fi) 1996-06-09
FI945783L (fi) 1996-06-09
FI945783A0 (fi) 1994-12-08

Similar Documents

Publication Publication Date Title
CN1036728C (zh) 连续蒸煮纸浆的蒸煮器和蒸煮方法
US5147504A (en) Apparatus for treating pulp in a pressurized state
WO1996017996A1 (fr) Lavage de la pate a papier dans un systeme de lavage avec fractionnement
CA2231551C (fr) Apport de liquide de lavage dans un dispositif de lavage a fractionnement et a plusieurs etages
JPS61152892A (ja) セルロースパルプの製造法
EP0884415A1 (fr) Procédé pour le lavage de pâte à papier pendant le blanchiment
CA2282065A1 (fr) Methode et dispositif pour reduire en pate, de facon continue, la matiere cellulosique fibreuse
EP0420860B1 (fr) Procede et appareil de fabrication de pulpe pour papier, carton, panneaux de fibres et produits similaires
CA2167922C (fr) Methode d'integration du blanchiment et de la recuperation dans la production de pate
CN1981085A (zh) 降低浸煮器系统中结垢的方法
WO1984004114A1 (fr) Procede de lavage de pulpe
RU2099456C1 (ru) Способ получения волокнистой массы для производства бумаги, картона, древесноволокнистых плит и другой продукции, содержащей древесные и/или другие растительные волокна и устройства для осуществления способа
EP1644574B1 (fr) Procede de traitement de pate relie au blanchiment de pate chimique
US6113742A (en) Digester having screening arrangement for isothermal cooking of fibrous material
US6086713A (en) Method of treating pulp
US5022962A (en) Method for the treatment of spent liquors in pulp production
CA2578004C (fr) Appareil et procede de traitement de pate a papier
WO1995008021A1 (fr) Phase eop pour la blanchiement sans chlorure
CA2089516A1 (fr) Procede de mise en pate et de blanchiment sans chlore
US5267655A (en) Method and apparatus for treating a gas containing aqueous fiber suspension
JPS6141385A (ja) 木材パルプの酸素アルカリ処理方法および装置

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): CA DE JP SE US

DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
ENP Entry into the national phase

Ref country code: US

Ref document number: 1997 849466

Date of ref document: 19970604

Kind code of ref document: A

Format of ref document f/p: F

REG Reference to national code

Ref country code: DE

Ref legal event code: 8642