WO2009136000A1 - Procédé au sulfate avec préhydrolyse - Google Patents

Procédé au sulfate avec préhydrolyse Download PDF

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Publication number
WO2009136000A1
WO2009136000A1 PCT/FI2009/050364 FI2009050364W WO2009136000A1 WO 2009136000 A1 WO2009136000 A1 WO 2009136000A1 FI 2009050364 W FI2009050364 W FI 2009050364W WO 2009136000 A1 WO2009136000 A1 WO 2009136000A1
Authority
WO
WIPO (PCT)
Prior art keywords
pressure
digester
bar
prehydrolyzed
cellulosic material
Prior art date
Application number
PCT/FI2009/050364
Other languages
English (en)
Inventor
Olavi Katajisto
Lari Lammi
Antti Viro
Original Assignee
Metso Paper, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Metso Paper, Inc. filed Critical Metso Paper, Inc.
Priority to CN2009801162710A priority Critical patent/CN102016162A/zh
Priority to US12/991,554 priority patent/US20110056637A1/en
Priority to EP09742200A priority patent/EP2286022A1/fr
Publication of WO2009136000A1 publication Critical patent/WO2009136000A1/fr

Links

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
    • D21C1/00—Pretreatment of the finely-divided materials before digesting
    • D21C1/02—Pretreatment of the finely-divided materials before digesting with water or steam
    • 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
    • D21C1/10—Physical methods for facilitating impregnation
    • 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
    • D21C3/02—Pulping cellulose-containing materials with inorganic bases or alkaline reacting compounds, e.g. sulfate processes

Definitions

  • the present invention relates to an improved prehydrolysis sulfate (Kraft) cooking process. It is disclosed an improved method for terminating the hydrolysis stage of the prehydrolysis sulfate cooking process. More precisely the invention relates to the termination of the hydrolysis stage operating in the steam phase, wherein the termination of said stage is also performed in the steam phase.
  • the prehydrolysis-sulfate (Kraft) cooking for the production of special pulps having a high content of alpha cellulose was developed in the 1930's, see e.g. Rydholm, S. E., Pulping Processes, pp. 649 to 672, Interscience Publishers, New York, 1968.
  • the basic idea is to remove as much hemicellulose as possible from cellulose fibers in connection with delignification, so as to obtain a high content of alpha cellulose. This is essential because the various end uses of such pulps, dissolving pulp for instance, do not tolerate short-chained hemicellulose molecules with a randomly grafted molecular structure.
  • a separate prehydrolysis step permits the desired adjustment of the hydrolysis of hemicelluloses by varying the hydrolysis conditions.
  • the prehydrolysis is carried out either as a water or steam phase prehydrolysis, or in the presence of a catalyst.
  • organic acids liberated from wood during the process perform a major part of the hydrolysis
  • small amounts of mineral acid or sulfur dioxide are added to "assist" the prehydrolysis.
  • direct steam is introduced to the chip column in the digester.
  • the prehydrolyzed material is conventionally neutralized with alkali containing liquid either by displacement or circulation.
  • Neutralization is achieved by selecting an appropriate neutralizing alkali charge, which results in clearly alkaline neutralization end point.
  • Suitable neutralizing agents to be used contain caustic soda, and the preferred agent is alkaline Kraft cooking liquor, i.e., white liquor.
  • the displacement process can be performed for example by filling up the digester with white liquor so that the leading edge of the white liquor neutralizes the hydrolysate.
  • alkali- containing liquid is pumped into the digester so as to displace the hydrolysate from outside the chips.
  • the neutralization is completed by circulating the liquid in the digester and thus mixing the contents therewith.
  • the neutralization step also serves as an alkaline hemicellulose-dissolving step.
  • the strong alkali and the high temperature directly dissolve and, on the other hand, degrade hemicellulose by the so-called end- wise peeling reaction.
  • the pulp is thus further purified, which leads to higher pulp viscosity and higher alpha cellulose content.
  • the neutralization step also becomes, in part, an alkaline extraction stage prior to the cooking step. Therefore the liquor-to- wood ratio in this step is preferably relatively low, such as between about 2.5 and 3.5.
  • the neutralized prehydrolyzed cellulosic material is delignified with alkaline cooking liquor (containing sodium sulfide and sodium hydroxide).
  • alkaline cooking liquor containing sodium sulfide and sodium hydroxide.
  • the delignification step has been a conventional Kraft cooking method, where white liquor has been added to the digester and the cooking has been carried out as a single step.
  • the acidic hydrolysis stage of the prehydrolysis sulfate (Kraft) cooking of the prior art is terminated (i.e. neutralized) e.g. by filling up the digester with white liquour or with some other alkali-containing liquid to effect the pH change and to be able to transfer from the acidic hemicellulose-splitting condition/state to an alkaline lignin-dissolving sulfate cooking state.
  • the neutralization i.e. termination of the hydrolysis stage is performed in the same way independent whether the prehydrolysis is operated in liquid or in steam phase. Both of the above-mentioned neutralization methods i.e. circulation and displacement are time-consuming, which makes the uniformity of the neutralization poorer.
  • the main object of the present invention is to provide an improved process for the preparation of pulp from lignin-containing cellulosic material, wherein the prehydrolysis is carried out in a steam phase and the termination (i.e. the neutralization of the contents of the digester) of the prehydrolysis stage is also carried out in a steam phase in order to overcome the problems associated with the prior art.
  • the steam phase termination is carried out by adding alkaline liquid in a prevailing pressure into the digester and then temporarily reducing the pressure of the digester. As a result of the pressure reduction the added alkaline liquid evaporates to the gas space of the digester thus neutralizing the prehydrolyzed material in the digester.
  • the present invention is directed to a process for the preparation of prehydrolyzed pulp in a digester from lignin-containing cellulosic material comprising a) prehydrolyzing said cellulosic material in a first steam phase at a first pressure to obtain prehydrolyzed cellulosic material b) terminating the prehydrolyzing operation in a termination stage c) delignifying the prehydrolyzed cellulosic material in a cooking stage, wherein the termination stage comprises at least one addition of an alkaline liquid at the first pressure followed by at least one pressure reduction.
  • the prehydrolysis stage is carried out in a steam phase, by introducing direct steam to the chip column in the digester at a temperature of about 150-180 0 C, preferably at a temperature of 160-170 0 C.
  • the steaming is normally started with a low-pressure steam (LP; appr. 3,5 bar, 150 0 C) and then continued with a medium pressure steam (MP; appr. 10,5 bar, 200 0 C) until the desired temperature in the venting line of the digester is obtained, i.e. the temperature of the digester contents is about 150- 180 0 C.
  • the temperature inside the digester is measured from the temperature of the venting gas in the venting line.
  • the pressure inside the digester can vary between 4,8 bar and 10,0 bar, preferably it is in the range of about 6 to about 9 bar.
  • a suitable prehydrolyzing time is from about 10 to 200 minutes, preferably from about 20 to 120 minutes.
  • the contents of the digester are neutralized, i.e. the prehydrolysis stage is terminated by a termination stage, which stage comprises at least one addition of an alkaline liquid at a prevailing pressure (i.e. at a first pressure) followed by at least one pressure reduction to a second pressure.
  • a termination stage which stage comprises at least one addition of an alkaline liquid at a prevailing pressure (i.e. at a first pressure) followed by at least one pressure reduction to a second pressure.
  • the first pressure is always higher than the second pressure.
  • the pressure difference between the first pressure and the second pressure i.e. the magnitude of the pressure drop, depends on several process variables, e.g. strength of the alkali, degree of packing and pressure of the digester.
  • the pressure of the digester is reduced so that the alkali charged/introduced evaporates and thus neutralizes the prehydrolyzed material in the digester.
  • This termination stage can also be called as a neutralization stage, as the acidic prehydrolyzed material is neutralized during this step.
  • the amount of alkali charged is determined so that all the liquid (free liquid outside the chips and liquid trapped and immobilized inside the chips) in the digester is neutralized and alkaline conditions are obtained that is pH is 7 or more.
  • suitable alkaline liquid for example alkalized black liquor, preferably white liquor.
  • the first pressure being the pressure of the end of the prehydrolysis stage i.e. between 4,8 bar and 10,0 bar, preferably being in the range of about 6 to about 9 bar.
  • the pH of the digester contents cannot be directly measured, thus, normally, the alkaline conditions are ensured by feeding some extra amount of alkaline liquid into the digester.
  • the pressure of the digester is momentarily reduced from the first pressure to a second pressure, which is about 2-7 bar, preferably about 3-5 bar.
  • the pressure is reduced for a period of about 1 second to 10 minutes, preferably for a period of 30 seconds to 5 minutes.
  • an alkaline delignifying step In the delignifying step the digester is filled up with the cooking chemicals, the temperature is increased to the cooking temperature, which is maintained until the desired degree of delignification is obtained.
  • the pressure reduction of the termination stage is performed gradually.
  • suitable alkaline liquid for example alkalized black liquor, preferably white liquor
  • the pressure is reduced gradually step-by-step, for example 0.5-2 bar at a time, to obtain the end pressure, which is about 2-7 bar, preferably 3-5 bar.
  • the digester is filled up with the cooking chemicals and thus the preparation of the pulp is continued by an alkaline delignifying step.
  • the total amount of the needed (2-15 % as NaOH on wood) suitable alkaline liquid for example alkalized black liquor preferably white liquor, is gradually added into the digester and after each addition the pressure is reduced from the previous pressure.
  • suitable alkaline liquid for example alkalized black liquor preferably white liquor
  • the pressure is reduced for a suitable period of time i.e. for a period of about 1 second to 10 minutes, preferably for a period of 30 seconds to 5 minutes.
  • rest of the alkaline liquid is added into the digester followed by a second pressure drop.
  • the amount of alkaline liquid needed can also be added in more than two batches. Each addition of alkaline liquid is followed by a pressure reduction.
  • the pressure can be reduced e.g. gradually so that after the addition of alkaline liquid the reduction of the pressure is 0,5-1 bar, preferably 0,5-0,7 bar from the previous pressure.
  • the neutralizing liquid is preferably introduced into the digester through the bottom of the digester, but other possible ways are also within the scope of the invention.
  • the prehydrolyzed cellulosic material is delignified by a conventional sulfate cooking method.
  • the cooking chemicals e.g. white liquor and spent black liquor
  • the digester contents are then heated by direct steam or via indirect heating of the recirculating pulping liquor in a heat exchanger.
  • a suitable cooking temperature is from about 150 0 C to 180 0 C, preferably from about 150 0 C to 165 0 C for hardwoods, and from about 155 0 C to 170 0 C for softwoods.
  • the digester contents are blown to a blow tank.
  • the contents of the digester were neutralized, in other words the prehydrolysis stage was completed, by a liquid phase neutralization process, i.e. circulation or displacement, which are very time-consuming and therefore the process conditions in the upper part of the digester are totally different compared to the process conditions in the lower part of the digester in the end of the neutralizing step.
  • the termination or the neutralization of the prehydrolysis stage is carried out very quickly compared to the prior art processes.

Abstract

La présente invention concerne un procédé de préparation d'une pâte à papier préhydrolysée dans un lessiveur à partir d'un matériau cellulosique contenant de la lignine. Selon la présente invention, le matériau cellulosique est préhydrolysé au cours d'une première étape en phase vapeur et sous une première pression pour obtenir un matériau cellulosique préhydrolysé. L'arrêt de l'opération de préhydrolyse, c'est-à-dire la neutralisation du matériau préhydrolysé, est réalisé par addition dans le lessiveur d'un liquide alcalin toujours à la même première pression, cela étant suivi d'au moins une réduction de la pression.
PCT/FI2009/050364 2008-05-08 2009-05-06 Procédé au sulfate avec préhydrolyse WO2009136000A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
CN2009801162710A CN102016162A (zh) 2008-05-08 2009-05-06 预水解硫酸盐蒸煮方法
US12/991,554 US20110056637A1 (en) 2008-05-08 2009-05-06 Prehydrolysis sulfate cooking process
EP09742200A EP2286022A1 (fr) 2008-05-08 2009-05-06 Procédé au sulfate avec préhydrolyse

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI20085425A FI20085425L (fi) 2008-05-08 2008-05-08 Sulfaattiesihydrolyysikeittomenetelmä
FI20085425 2008-05-08

Publications (1)

Publication Number Publication Date
WO2009136000A1 true WO2009136000A1 (fr) 2009-11-12

Family

ID=39523080

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/FI2009/050364 WO2009136000A1 (fr) 2008-05-08 2009-05-06 Procédé au sulfate avec préhydrolyse

Country Status (5)

Country Link
US (1) US20110056637A1 (fr)
EP (1) EP2286022A1 (fr)
CN (1) CN102016162A (fr)
FI (1) FI20085425L (fr)
WO (1) WO2009136000A1 (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2011138634A1 (fr) * 2010-05-04 2011-11-10 Bahia Specialty Cellulose Sa Procédé et système de production de pâte à papier par dissolution à alpha élevé
WO2012158075A1 (fr) * 2011-05-13 2012-11-22 Metso Paper Sweden Ab Procédé compact d'obtention de pâte préalablement hydrolysée
US8535480B2 (en) 2010-05-06 2013-09-17 Bahia Specialty Cellulose Sa Method and system for pulp processing using cold caustic extraction with alkaline filtrate reuse
AU2010202496B2 (en) * 2010-05-04 2015-04-16 Bahia Specialty Cellulose Sa Method and system for high alpha dissolving pulp production
EP3417102A4 (fr) * 2016-02-16 2019-10-30 Valmet AB Procédé de récupération d'hydrolysat concentré après l'hydrolyse de matière de cellulose
EP3673110A4 (fr) * 2017-08-25 2021-05-12 Valmet AB Procédé compact amélioré pour la production d'une pâte préhydrolysée

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102337693B (zh) * 2011-09-30 2014-01-22 重庆理文造纸有限公司 一种溶解浆的蒸煮及洗涤工艺
CN108252141A (zh) * 2018-01-04 2018-07-06 安徽工程大学 一种蔺草纤维及其湿法非织造织物的制备方法
SE1950606A1 (en) * 2019-05-22 2020-10-13 Valmet Oy A method for extracting hydrolyzate, a batch cooking system and a hydrolyzate extracting arrangement

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB758766A (en) * 1954-05-10 1956-10-10 Brown And Root Inc Process for the production of pulp from bagasse
US3013933A (en) 1953-01-28 1961-12-19 Rayonier Inc Method for preparation of wood cellulose
US5203963A (en) * 1991-10-21 1993-04-20 A. Ahlstrom Corporation Continuous treatment of small chips
US5676795A (en) * 1992-12-02 1997-10-14 Voest-Alpine Industrieanlagenbau Gmbh Process for the production of viscose pulp
WO2000034568A1 (fr) * 1998-12-08 2000-06-15 Rhodia Acetow Gmbh Procede de preparation de pate a usage chimique a partir de copeaux de bois
WO2003106765A1 (fr) * 2001-12-17 2003-12-24 Kvaerner Pulping Ab Procede et systeme d'impregnation de copeaux
SE523850C2 (sv) * 1997-09-22 2004-05-25 Kvaerner Pulping Tech Förfarande vid förbehandling av flis med basningsånga och impregneringsvätska
WO2006128304A1 (fr) 2005-06-03 2006-12-07 Iogen Energy Corporation Procede de traitement en continu de matieres premieres lignocellulosiques
WO2007090926A1 (fr) * 2006-02-10 2007-08-16 Metso Paper, Inc. Procédé de récupération de produits d'hydrolyse

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5198074A (en) * 1991-11-29 1993-03-30 Companhia Industreas Brasileiras Portela Process to produce a high quality paper product and an ethanol product from bamboo

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3013933A (en) 1953-01-28 1961-12-19 Rayonier Inc Method for preparation of wood cellulose
GB758766A (en) * 1954-05-10 1956-10-10 Brown And Root Inc Process for the production of pulp from bagasse
US5203963A (en) * 1991-10-21 1993-04-20 A. Ahlstrom Corporation Continuous treatment of small chips
US5676795A (en) * 1992-12-02 1997-10-14 Voest-Alpine Industrieanlagenbau Gmbh Process for the production of viscose pulp
SE523850C2 (sv) * 1997-09-22 2004-05-25 Kvaerner Pulping Tech Förfarande vid förbehandling av flis med basningsånga och impregneringsvätska
WO2000034568A1 (fr) * 1998-12-08 2000-06-15 Rhodia Acetow Gmbh Procede de preparation de pate a usage chimique a partir de copeaux de bois
WO2003106765A1 (fr) * 2001-12-17 2003-12-24 Kvaerner Pulping Ab Procede et systeme d'impregnation de copeaux
WO2006128304A1 (fr) 2005-06-03 2006-12-07 Iogen Energy Corporation Procede de traitement en continu de matieres premieres lignocellulosiques
WO2007090926A1 (fr) * 2006-02-10 2007-08-16 Metso Paper, Inc. Procédé de récupération de produits d'hydrolyse

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2011138634A1 (fr) * 2010-05-04 2011-11-10 Bahia Specialty Cellulose Sa Procédé et système de production de pâte à papier par dissolution à alpha élevé
AU2010202496B2 (en) * 2010-05-04 2015-04-16 Bahia Specialty Cellulose Sa Method and system for high alpha dissolving pulp production
US8535480B2 (en) 2010-05-06 2013-09-17 Bahia Specialty Cellulose Sa Method and system for pulp processing using cold caustic extraction with alkaline filtrate reuse
US8734612B2 (en) 2010-05-06 2014-05-27 Bahia Specialty Cellulose Method and system for high alpha dissolving pulp production
WO2012158075A1 (fr) * 2011-05-13 2012-11-22 Metso Paper Sweden Ab Procédé compact d'obtention de pâte préalablement hydrolysée
EP2707539A1 (fr) * 2011-05-13 2014-03-19 Metso Paper Sweden AB Procédé compact d'obtention de pâte préalablement hydrolysée
EP2707539A4 (fr) * 2011-05-13 2014-11-19 Valmet Aktiebolag Procédé compact d'obtention de pâte préalablement hydrolysée
EP3417102A4 (fr) * 2016-02-16 2019-10-30 Valmet AB Procédé de récupération d'hydrolysat concentré après l'hydrolyse de matière de cellulose
EP3673110A4 (fr) * 2017-08-25 2021-05-12 Valmet AB Procédé compact amélioré pour la production d'une pâte préhydrolysée

Also Published As

Publication number Publication date
FI20085425L (fi) 2009-11-09
US20110056637A1 (en) 2011-03-10
CN102016162A (zh) 2011-04-13
EP2286022A1 (fr) 2011-02-23
FI20085425A0 (fi) 2008-05-08

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