EP0662169B1 - Procede de lessivage continu de materiau en fibre cellulosique - Google Patents

Procede de lessivage continu de materiau en fibre cellulosique Download PDF

Info

Publication number
EP0662169B1
EP0662169B1 EP92918282A EP92918282A EP0662169B1 EP 0662169 B1 EP0662169 B1 EP 0662169B1 EP 92918282 A EP92918282 A EP 92918282A EP 92918282 A EP92918282 A EP 92918282A EP 0662169 B1 EP0662169 B1 EP 0662169B1
Authority
EP
European Patent Office
Prior art keywords
liquid
impregnating
fibre material
withdrawn
digester
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.)
Expired - Lifetime
Application number
EP92918282A
Other languages
German (de)
English (en)
Other versions
EP0662169A1 (fr
Inventor
Ake Backlund
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.)
Metso Fiber Karlstad AB
Original Assignee
Kamyr AB
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 Kamyr AB filed Critical Kamyr AB
Publication of EP0662169A1 publication Critical patent/EP0662169A1/fr
Application granted granted Critical
Publication of EP0662169B1 publication Critical patent/EP0662169B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

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
    • D21C3/00—Pulping cellulose-containing materials
    • D21C3/22—Other features of pulping processes
    • D21C3/24—Continuous processes
    • 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
    • D21C1/00—Pretreatment of the finely-divided materials before digesting

Definitions

  • the present invention relates to a process for the continuous digestion of cellulosic fiber material, comprising impregnation with impregnating liquid consisting of at least one fresh digesting liquor, in a closed impregnating system and subsequent digestion with digesting liquid in a closed digester system, said impregnating liquid being added through a supply system, together with steamed fibre material, to an inlet end of the impregnating system, liquid being withdrawn from the impregnating system at a point located at a predetermined distance from said inlet end.
  • the liquid to wood ratio at the inlet to a continuous digester is normally 3.0 - 3.5 m 3 per ton dry chips.
  • conventional sulphate cooking 70-100% of the white liquor required is normally added to the supply system for the impregnating vessel via a high-pressure pump.
  • the amount of liquid at the inlet to the impregnating vessel may then be within an interval of about 2.4 - 2.8 m 3 per ton dry chips, distributed as follows: A Chips moisture (moisture content 50 %) 1.0 m 3 B+C Steam condensate 0.3 m 3 E White liquor (70-100%) 1.1-1.5 m 3
  • black liquor can be added to the impregnating vessel through the supply system in order to increase the liquid to wood ratio, for instance to 3.0 m 3 or above.
  • the temperature of the black liquor should not exceed 100 C°. If too little liquid is added to the impregnating vessel, disturbances will result in the supply system due to the formation of steam in the down pipe located before the high pressure valve. The temperature of the liquid exceeds the temperature corresponding to the steam pressure in the pressure steaming vessel located upstream. Sinking of the chips in the impregnating vessel is also impeded. The quantity of free liquid, i.e. the portion of liquid which is not absorbed by the chips, becomes too low and the flow rate of the liquid is correspondingly reduced.
  • the flow rate of the free liquid exerts a driving force on the column of chips. It is important that this driving force is great in the upper part of the impregnating vessel where the chips are still not saturated with liquid but have a tendency to float. This requirement is of less importance in the lower part of the impregnating vessel since by this stage the chips are substantially saturated with liquid and therefore tend to sink due to their own weight.
  • the process or operating economy requires that the digesting liquid of the first step has to be added in a limited quantity, in which case it may be difficult to achieve a sufficiently high liquid to wood ratio.
  • the liquid flow at the entrance to the digester must be controlled so that it does not become too great since this results in too great a consumtion of high-pressure steam in heat exchanger present in the transfer system and of direct steam to the top of the digester.
  • the withdrawal strainer in the upper part of the countercurrent flow washing zone of the digester becomes overloaded.
  • the object of the present invention is to eliminate said problems and provide a simple and reliable method of maintaining a sufficiently high flow of liquid in at least the initial part of the impregnating vessel without the liquid flow in the digester becoming too high.
  • the invention aims to solve the problems existing when black liquor cannot be used in order to provide a sufficiently high liquid to wood ratio in the impregnating vessel without such ratio being too high in the digester.
  • the process according to the invention is characterised in that such a first quantity of liquid (F) is whithdrawn at said withdrawal point and recirculated directly to the supply system that a predetermined minimum ratio between liquid and fibre material is continuously maintained in the impregnating system prior to said withdrawal point, the liquid in said liquid to fibre material ratio being derived from original moisture (A) in the fibre material, condensates (B, C) from an initial steaming of the fibre material, and added fresh digesting liquor(s) (D and/or E) besides said withdrawn and recirculated quantity of liquid (F).
  • the term "directly” as used herein means that the liquid is recirculated as such to the supply system, i.e. without being mixed with black liquor.
  • the plant shown in the drawing comprises a vertical steaming vessel 1, a horizontal steaming vessel 2, a vertical impregnating vessel 3 and a vertical digester 4. Chips are fed through a pipe 5 to the vertical steaming vessel 1, to which low pressure steam is supplied through a pipe 6 in order to heat the chips and reduce their air content. This pre-steaming process is performed at atmospheric pressure.
  • the heated chips are dosed by a chip meter disposed in a connection 7 between the two steaming vessels, said connection 7 also containing a lower-pressure valve 8 which locks through the chips into the horizontal steaming vessel 2.
  • Low-pressure steam is added through a pipe 9.
  • the pressure in this second steam vessel 2 is 1-1.5 bar over-pressure.
  • the chips fall into a down pipe 10 with a high pressure valve 11 disposed at the lower end thereof.
  • a liquid level is maintained in the down pipe 10.
  • the high pressure valve 11 is provided with a rotor having pockets. One pocket is always in low pressure position to be in open communication with the pre-steaming vessel 1, and another pocket is always simultaneously in high pressure position to be in open communication with the impregnating vessel 3 via a supply pipe 12 connected to the top of the impregnating vessel 3.
  • Liquid in a circulation loop 13 provided with a pump 20 feeds the chips from the down pipe 10 into the high pressure valve 11 and fills one of the rotor pockets.
  • a screen is mounted in the housing of the high pressure valve 11 to prevent chips from accompanying the circulation liquid in the circulation loop 13.
  • the liquid displaced by the chips in the high pressure valve 11 is withdrawn from the circulation loop 13 by means of a screen 14 disposed therein, from which the liquid withdrawn is conducted to a level tank 15 via a pipe 16.
  • the level tank 15 is connected to the top of the impregnating vessel 3 by a pipe 17 containing a high-pressure pump 18 to pump the liquid withdrawn into the impregnating vessel 3.
  • the high pressure valve 11 and impregnating vessel 3 are connected by means of a circulation loop comprising said supply pipe 12 which is connected to the top of the impregnating vessel 3, and a return pipe 21 which connects the top of the impregnating vessel to the high pressure valve 11 to return liquid separated off by a top separator disposed in the impregnating vessel 3.
  • the liquid is caused to circulate by means of a pump 22 located in the return pipe 21.
  • a pump 22 located in the return pipe 21.
  • the flow rate of the return liquid is so high that it flushes the chips from the rotor pocket with it into the impregnating vessel 3.
  • the pressure in the impregnating vessel 3 is normally 8-15 bar over-pressure. However, for certain processes it may be as high as 15-45 bar over-pressure.
  • Fresh digesting liquor D from a first storage tank is fed to the top of the impregnating vessel 3 via a pipe 23.
  • the pipe 23 is suitably connected to the pipe 17 from the level tank 15 so that the high-pressure pump 18 is utilized for pumping both the liquid withdrawn from the first circulation loop 13, and the digesting liquor D which thus constitutes fresh impregnating liquid.
  • Fresh digesting liquor E is fed to the digester from a second storage tank via a pipe 24 containing a high-pressure pump 25.
  • Some of the digesting liquor E may be used as impregnating liquid and be fed to the top of the impregnating vessel 3 via a branch pipe 26 provided with a valve.
  • This branch pipe 26 is suitably connected to the pipe 17 from the level tank 15.
  • the impregnated chips are transferred from the bottom of the impregnating vessel 3 to the top of the digester 4 via a pipe 27.
  • a strainer is mounted at the top of the digester 4 to separate off a certain amount of liquid which is then returned to the bottom of the impregnating vessel 3 via a return pipe 28 containing a pump 29 to pump the chips to the digester 4 with the aid of the separated liquid.
  • the return pipe 28 passes a heat exchanger 30 to heat the liquid passing it by the supply of high-pressure steam via a pipe 31.
  • the supply pipe 27 and return pipe 28 form a transfer circulation for the suspension of impregnated chips and boiling liquid.
  • a larger quantity of digesting liquor E is added to said transfer circulation in that the pipe 24 for the digesting liquor is connected to the return pipe 28 before pump 29.
  • a smaller quantity of the digesting liquor may be added to a circulation pipe 33 of the digester, via a pipe 19 provided with a valve.
  • the digester is provided with a strainer 32 for circulation of liquid through pipe 33 with the aid of a pump 34, the liquid being heated in a heat exchanger 35.
  • the pipe 33 comprises a central tube disposed in the centre of the digester with its orifice at the strainer 32.
  • the digested chips are washed in countercurrent flow in the lower part of the digester, using washing liquid supplied through a pipe 36 and pumped by a high-pressure pump 37 into the lower part of the digester in an amount which is regulated to ensure that the digester is kept filled with liquid.
  • the washing liquid is heated indirectly by steam which is supplied to a heat exchanger 38 disposed in a pipe 39 for circulation of washing liquid by means of a pump 40.
  • the washing liquid is removed through a strainer 41 and returned through a central pipe extending from the bottom of the digester and having its orifice at a strainer 41.
  • the washing liquid heated in this manner is forced to flow in countercurrent up through the chips column as it moves slowly downwards, thereby displacing its content of spent digesting liquor which is withdrawn through a strainer 42 and conducted via a pipe 43 to a flash cyclone (not shown) and a recovery plant (not shown).
  • the digested chips are fed out at the bottom of the digester using suitable scrapers, and is conducted through a pipe 44 for continued processing.
  • indirect heating of digesting liquid and wood in said transfer circulation 27, 28 is also performed with steam supplied to the top of the digester through a pipe 45.
  • the impregnating vessel is provided with a strainer 46 disposed at a predetermined distance from the top of the impregnating vessel as seen from the point where the chips are supplied, i.e. the inlet end.
  • a return pipe 47 provided with a valve is connected between this strainer 46 and the top of the impregnating vessel in order to return a predetermined quantity of liquid to the start of the impregnating zone.
  • the return pipe 47 contains a high-pressure pump 48 and passes through a heat exchanger 49, the other fluid side of which is connected to the pipe 24 for fresh digesting liquor E via branch pipes 50, 51.
  • the flow to the heat exchanger 49 is regulated by a valve 52 in the pipe 24 for fresh digesting liquor E.
  • the return pipe 47 is connected to the pipe 17 from the level tank 15 at a point located before the high-pressure pump 18.
  • the impregnating liquid D is added in an amount of about 0.7 m 3 per ton dry wood.
  • the quantity of liquid A from chips moisture is about 1.0 m 3 and from the steam condensates B and C about 0.3 m 3 per ton dry wood. These three sources of liquid thus supply about 2.0 m 3 per ton dry wood to the top of the impregnating vessel 3.
  • Liquid F is withdrawn from the strainer 46 in the impregnating vessel in an amount of about 1.0 m 3 per ton dry wood. The liquid F withdrawn is cooled to a suitable temperature in the cooler 49 in order to avoid disturbances in the supply system.
  • the total amount of the liquids A, B, C, D and F is thus about 3.0 m 3 per ton dry wood.
  • This quantity of liquid is sufficient to provide a constant downward movement of the chips column in the impregnating vessel 3.
  • the amount of liquid F may be varied within wide limits, depending on the other liquid flows to the impregnating vessel and on other operating conditions.
  • Digesting liquor E in the form of white liquor is supplied to the digester 4 via pipes 24, 28, 27 and 19 in an amount of about 1.5 m 3 per ton dry chips. All together about 3.5 m 3 liquid per ton dry chips is thus transferred to the digester, i.e. the sum of the liquid quantities A, B, C, D and E. This gives an acceptable flow of liquid in the digester 4 with respect to heat economy and operating reliability.
  • the temperature at the top of the impregnating vessel is generally about 110-120 C° and at the bottom, i.e. in the transfer circulation 27, 28, about 130-160 C°.
  • the liquid withdrawn through the strainer 46 has a temperature of about 120-130 C°, while the black liquor withdrawn from the digester through the strainer 42 has a temperature of about 150-170 C°.
  • the method according to the invention for maintaining a sufficiently high flow of liquid in the upper part of the impregnating vessel can be utilized for various embodiments of the digesting process.
  • the fresh digesting liquor D may consist of an alkaline solution with a high sodium sulphide content or of only sodium sulphide. Sodium sulphide is consumed to a relatively small extent during impregnation conditions and a sufficiently high sodium sulphide content can therefore be maintained even if impregnating liquid F is withdrawn and returned to the inlet of the impregnating vessel.
  • the fresh digesting liquor E may consist of ordinary white liquor, i.e. a mixture of substantially sodium sulphide and sodium hydroxide, or a white liquor containing substantially sodium hydroxide.
  • the liquid F withdrawn from the initial concurrent flow impregnating zone may be large enough to correspond to all the free liquid.
  • the liquid bound by the chips is about 1.8 m 3 per ton dry wood in the case of softwood and about 1.0-1.5 m 3 per ton dry wood in the case of hardwood, depending on the density of the chips.
  • Withdrawing additional liquid through strainer 46 will cause liquid to flow upwardly from the bottom of the impregnating vessel towards the strainer 46. In such an operation some of the digesting liqour E which has been added to the transfer circulation will meet the chips in countercurrent flow, thereby resulting in improved impregnation.
  • the additional liquid withdrawn from the lower countercurrent flow impregnating zone via the strainer 46 can be returned to the transfer circulation 27, 28 or be used in som other way. It is thus not included when calculating the amount of liquid F which is withdrawn and returned to the supply system.
  • the temperature in the impregnating vessel 3 can advantageously be regulated to a suitable level by cooling the withdrawn impregnating liquid F in the cooler 49.
  • the fresh digesting liquor D may also consist of an organic substance, such as methanol or ethanol, to impregnate the steamed chips, possibly in the presence of a small quantity of fresh digesting liquor E, e.g. white liquor.
  • the rest of the fresh digesting liquor E is then added to the transfer circulation 27, 28 and/or one of the liquid circulations, e.g. 33, of the digester.
  • the process according to the invention is also applicable to sulphite digestion in several steps, for instance acid sulphite digestion. Neither is it limited to a continuous digester with separate impregnating vessel, but may be used in a digester vessel for the continuous digesting with initial impregnating zone, such as a one-vessel hydraulic digester.
  • the impregnating liquid F withdrawn may alternatively be returned to the supply system at a point in the pipe 17 located after the high-pressure pump 18. This reduces the need of pump energy.
  • liquid F withdrawn is enriched with gas, which may cause operating disturbance, it may be suitable to flash the liquid to a low pressure for degassing before feeding it to the sypply system.

Landscapes

  • Paper (AREA)
  • Artificial Filaments (AREA)
  • Treatments For Attaching Organic Compounds To Fibrous Goods (AREA)

Claims (10)

  1. Procédé de lessivage continu de matériau en fibre cellulosique, comprenant l'imprégnation à l'aide d'un liquide imprégnant se composant d'au moins une liqueur de lessivage fraîche, dans un système d'imprégnation clos, et un lessivage subséquent à l'aide d'un liquide de lessivage dans un système lessiveur clos, ledit liquide d'imprégnation étant alimenté à travers un système d'alimentation, conjointement à un matériau en fibre traité à la vapeur, à une extrémité d'entrée du système d'imprégnation, le liquide étant retiré du système d'imprégnation à un point (46) situé à une distance prédéterminée de ladite extrémité d'entrée, caractérisé en ce que l'on retire audit point de retrait (46) et en ce que l'on recycle directement dans le système d'alimentation une première quantité de liquide (F) telle qu'un rapport prédéterminé minimum entre liquide et matériau en fibre est maintenu en continu dans le système d'imprégnation avant ledit point de retrait (46), le liquide dans ledit rapport du liquide au matériau en fibre étant dérivé de l'humidité initiale (A) dans le matériau en fibre, des condensats (B, C) obtenus à partir d'un traitement à la vapeur initial du matériau en fibre, et de ou des liqueur(s) de lessivage fraîche(s) ajoutée(s) (D et/ou E) en plus de ladite quantité retirée et recyclée de liquide (F).
  2. Procédé selon la revendication 1, caractérisé en ce que ledit rapport du liquide au matériau en fibre est au moins de 2,5:1, de préférence au moins de 3,0:1, calculé sur la base du matériau en fibre sec.
  3. Procédé selon la revendication 1 ou 2, caractérisé en ce que la liqueur de lessivage fraîche (E), ajoutée à travers le système d'alimentation, se compose chimiquement de la même liqueur de lessivage fraîche (E), alimentée au système lessiveur.
  4. Procédé selon la revendication 1 ou la revendication 2, caractérisé en ce qu'une liqueur de lessivage fraîche (D) ayant une composition chimique différente de celle de la liqueur de lessivage fraîche (E) ajoutée au système lessiveur, est ajoutée au système d'alimentation.
  5. Procédé selon la revendication 4, caractérisé en ce qu'une partie de la liqueur de lessivage fraîche (E) pour le système lessiveur est également ajoutée au système d'alimentation.
  6. Procédé selon l'une quelconque des revendications 1-5, caractérisé en ce que la température dans le système d'imprégnation est régulée en forçant la première quantité de liquide (F), qui est retirée et recyclée à passer dans une échangeur de chaleur (49) avant d'être introduite dans le système d'alimentation.
  7. Procédé selon la revendication 6, caractérisé en ce que le liquide de lessivage qui est ajouté au système lessiveur ou à l'eau pour la production d'eau chaude, est utilisé en tant que milieu d'échange thermique.
  8. Procédé selon la revendication 4 ou 5, caractérisé en ce qu'une solution neutre ou alcaline de sulfure de sodium, une solution d'un composé organique tel que le méthanol et l'éthanol, une solution de polysulfure ou une solution d'anthraquinone est utilisée en tant que ladite liqueur de lessivage (D) de composition chimique différente.
  9. Procédé selon l'une quelconque des revendications 1-8, caractérisé en ce que la quantité de liquide (F), retirée et recyclée dans le système d'alimentation, est équivalente à la quantité de liquide libre dans le système d'imprégnation avant le point de retrait (46).
  10. Procédé selon la revendication 9, caractérisé en ce qu'un écoulement à contre-courant est maintenu en aval du point de retrait (46), vu du point de vue du mouvement du matériau en fibre, en retirant une deuxième quantité de liquide du système d'imprégnation, en sus dudit liquide libre (F), ladite deuxième quantité de liquide constituant une partie d'un liquide qui est introduit à l'extrémité de sortie du système d'imprégnation pour transférer le matériau en fibre imprégné au système lessiveur.
EP92918282A 1991-08-23 1992-08-11 Procede de lessivage continu de materiau en fibre cellulosique Expired - Lifetime EP0662169B1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
SE9102427 1991-08-23
SE9102427A SE469078B (sv) 1991-08-23 1991-08-23 Saett vid kontinuerlig kokning av cellulosahaltigt fibermaterial
PCT/SE1992/000546 WO1993004232A1 (fr) 1991-08-23 1992-08-11 Procede de lessivage continu de materiau en fibre cellulosique

Publications (2)

Publication Number Publication Date
EP0662169A1 EP0662169A1 (fr) 1995-07-12
EP0662169B1 true EP0662169B1 (fr) 1996-11-06

Family

ID=20383529

Family Applications (1)

Application Number Title Priority Date Filing Date
EP92918282A Expired - Lifetime EP0662169B1 (fr) 1991-08-23 1992-08-11 Procede de lessivage continu de materiau en fibre cellulosique

Country Status (11)

Country Link
EP (1) EP0662169B1 (fr)
JP (1) JPH06510091A (fr)
AT (1) ATE145025T1 (fr)
AU (1) AU2490392A (fr)
CA (1) CA2115578A1 (fr)
DE (1) DE69215110T2 (fr)
FI (1) FI940826A0 (fr)
ID (1) ID848B (fr)
PT (1) PT100799A (fr)
SE (1) SE469078B (fr)
WO (1) WO1993004232A1 (fr)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5413677A (en) * 1993-04-05 1995-05-09 Kamyr, Inc. Method for producing chemical pulp from hardwood chips
SE506703C2 (sv) 1995-07-12 1998-02-02 Kvaerner Pulping Tech Impregnering av fibermaterial i medström vid kontinuerlig kokning
US7297236B1 (en) 2001-06-30 2007-11-20 Icm, Inc. Ethanol distillation process
SE527058C2 (sv) * 2004-02-09 2005-12-13 Kvaerner Pulping Tech Kontinuerlig kokprocess med förbättrad värmeekonomi
SE0602675L (sv) * 2006-12-13 2007-09-18 Metso Fiber Karlstad Ab Metod för att energieffektivt producera cellulosamassa i ett kontinuerligt kokeri
US9644317B2 (en) 2014-11-26 2017-05-09 International Paper Company Continuous digester and feeding system

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE359331B (fr) * 1970-03-17 1973-08-27 Kamyr Ab
SE468053B (sv) * 1988-12-20 1992-10-26 Kamyr Ab Saett vid kontinuerlig uppslutningskokning av cellulosahaltigt fibermaterial

Also Published As

Publication number Publication date
FI940826A (fi) 1994-02-22
JPH06510091A (ja) 1994-11-10
WO1993004232A1 (fr) 1993-03-04
CA2115578A1 (fr) 1993-03-04
SE9102427L (sv) 1993-02-24
ATE145025T1 (de) 1996-11-15
SE469078B (sv) 1993-05-10
DE69215110T2 (de) 1997-04-03
AU2490392A (en) 1993-03-16
SE9102427D0 (sv) 1991-08-23
PT100799A (pt) 1994-05-31
FI940826A0 (fi) 1994-02-22
DE69215110D1 (de) 1996-12-12
EP0662169A1 (fr) 1995-07-12
ID848B (id) 1996-08-01

Similar Documents

Publication Publication Date Title
US5080755A (en) Process for the continuous digestion of cellulosic fiber material
US5536366A (en) Digester system for implementing low dissolved solids profiling
US7976675B2 (en) Continuous digester system
US3532594A (en) Method of digesting cellulosic material in steam phase
US5779856A (en) Cooking cellulose material using high alkali concentrations and/or high pH near the end of the cook
CA2066181C (fr) Methode de chauffage par deplacement pour lessiveur a cuisson continue
EP1778910B1 (fr) Procede d'impregnation de copeaux
US6123807A (en) Method for the continuous cooking of pulp
EP0662169B1 (fr) Procede de lessivage continu de materiau en fibre cellulosique
US5192396A (en) Process for the continuous digestion of cellulosic fiber material
US5256255A (en) Displacement heating in continuous digesters
EP0670925A1 (fr) Refroidissement de la ligne de circulation superieure pour lessiveur modifie.
US5529661A (en) Process for controlling the flow of cellulosic fiber material through an impregnation vessel
US20060070710A1 (en) Method and a device for preparing cellulose pulp
US5958181A (en) Continuous cooking with a two-stage cool impregnation
US3441475A (en) Continuous pulping apparatus
US6332950B1 (en) Method in connection with the pretreatment of comminuted fibrous material
US20040089430A1 (en) Method for alkaline cooking of fiber material

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 19940217

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AT DE ES FR SE

17Q First examination report despatched

Effective date: 19951005

GRAH Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOS IGRA

GRAH Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOS IGRA

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): AT DE ES FR SE

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: ES

Free format text: THE PATENT HAS BEEN ANNULLED BY A DECISION OF A NATIONAL AUTHORITY

Effective date: 19961106

REF Corresponds to:

Ref document number: 145025

Country of ref document: AT

Date of ref document: 19961115

Kind code of ref document: T

REF Corresponds to:

Ref document number: 69215110

Country of ref document: DE

Date of ref document: 19961212

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SE

Effective date: 19970206

ET Fr: translation filed
PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: AT

Payment date: 19970729

Year of fee payment: 6

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 19970811

Year of fee payment: 6

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 19970818

Year of fee payment: 6

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: AT

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 19980811

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 19990430

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 19990601

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST