EP1330572A1 - Procede de cuisson au moyen de liqueur noire chaude - Google Patents

Procede de cuisson au moyen de liqueur noire chaude

Info

Publication number
EP1330572A1
EP1330572A1 EP01983617A EP01983617A EP1330572A1 EP 1330572 A1 EP1330572 A1 EP 1330572A1 EP 01983617 A EP01983617 A EP 01983617A EP 01983617 A EP01983617 A EP 01983617A EP 1330572 A1 EP1330572 A1 EP 1330572A1
Authority
EP
European Patent Office
Prior art keywords
liquor
displaced
cooking
solids content
dry solids
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.)
Withdrawn
Application number
EP01983617A
Other languages
German (de)
English (en)
Inventor
Hannu Di Haaslahti
Olavi Katajisto
Osmo Keitaaniemi
Mikael Svedman
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 EP1330572A1 publication Critical patent/EP1330572A1/fr
Withdrawn legal-status Critical Current

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
    • D21C3/00—Pulping cellulose-containing materials
    • D21C3/02—Pulping cellulose-containing materials with inorganic bases or alkaline reacting compounds, e.g. sulfate 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
    • D21C11/00—Regeneration of pulp liquors or effluent waste waters
    • D21C11/0021—Introduction of various effluents, e.g. waste waters, into the pulping, recovery and regeneration cycle (closed-cycle)
    • 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
    • D21C11/00—Regeneration of pulp liquors or effluent waste waters
    • D21C11/04—Regeneration of pulp liquors or effluent waste waters of alkali lye

Definitions

  • the present invention concerns a method for producing pulp in an alkaline digesting process comprising the following steps: charging lignocellulosic material to a digester system; pre-treating said lignocellulosic material initially with an impregnation liquor and subsequently with at least a hotter liquor containing substantially black liquor, spent liquor being displaced from the digester during said treatment; heating and cooking said lignocellulosic material at a cooking temperature producing cooked lignocellulosic material and cooking liquor, said cooking liquor being at said cooking temperature and having an initial dry solids content; displacing a portion of said system cooking liquor at said cooking temperature from said digester to a first section by supplying a washing liquid to said digester in order to obtain a first portion of displaced cooking liquor having a first temperature and a first dry solids content; - further displacing a second portion of displaced liquor from said digester to at least a second section by supplying further washing liquid until the temperature of said second portion of displaced liquor drops to a
  • the object of the invention is to increase washing efficiency in the digester and to decrease the dry solids content of the cooking liquor in the digester when using hot black liquor treatments prior to cooking.
  • This is achieved with a method according to the preamble, characterized by the features that substantial parts of said second portion of displaced liquor is heated by the heat of the first portion of displaced liquor, whereby said first portion having a high solids content is prevented from being reused in the digester, and said heated second portion is further used as hot liquor in the pre-treatment and heating of said lignocellulosic material. Due to these features the dry solids content in the cooking liquor, and subsequent process stages, such as washing and bleaching will decrease significantly. This will result in easier washing and higher washing efficiency in the whole plant, in improved operation, improved pulp quality and bleachability without essentially affecting production capability or steam economy.
  • Fig. 1 shows a prior art embodiment according to a so called twin tank process, i.e. including two hot black liquor tanks;
  • Fig. 2 shows another prior art embodiment provided for handling calcium- rich raw materials;
  • Fig. 3 shows an embodiment according to the present invention also including the process for handling calcium-rich raw materials
  • Fig. 4 shows an embodiment according to the invention comprising only one HBL tank divided into two sections, thus different from the system of Fig. 3, and
  • lignocellulosic material such as wood chips is charged into the digester system.
  • the lignocellulosic material is pre- treated with an impregnation liquor A, having a temperature of below 120°C, preferably below the boiling point of said impregnation liquor from an atmospheric tank.
  • an impregnation liquor A having a temperature of below 120°C, preferably below the boiling point of said impregnation liquor from an atmospheric tank.
  • said impregnation liquor A is fed from a wash filtrate tank 6.
  • a smaller amount of white liquor can be added to said impregnation liquor A in order to adjust the alkali content.
  • the impregnation liquor A is fed from an impregnation liquor tank 5, preferably atmospheric, receiving cooled black liquor from a hot black liquor tank 2. Soap is removed from wash filtrate tank 6, impregnation liquor tank 5 and black liquor tank 4 and the soap is further conducted to recovery.
  • the lignocellulosic material is pre-treated with at least a hotter liquor B, having a temperature of about 120 to 180°C, and containing substantially black liquor from hot black liquor tank 1.
  • the pre-treatment is preferably carried out for a time and temperature corresponding to an H- l o factor of below 300.
  • the lignocellulosic material is then heated and cooked at a cooking temperature of 140 to 185°C, preferably 150 to 180°C, whereby cooked lignocellulosic material and cooking liquor is produced.
  • the cooking liquor is at said cooking temperature and it has an initial dry solids content.
  • a first portion D1 of the cooking liquor at said cooking temperature is displaced from the digester to a first section, i.e. to the hot black liquor tank 2 at point D, according to the invention , as shown in Fig. 3-4, by supplying a washing liquor E from the wash filtrate tank 6, in the process shown in Fig 5.
  • a washing liquor E from the wash filtrate tank 6, in the process shown in Fig 5.
  • the displacement is first carried out with a liquor E from the black liquor tank 4. Further displacement is carried out by supplying washing liquor F from the wash filtrate tank 6 to the digester whereby a second portion of displaced liquor B1 is displaced to a second section, i.e. to black liquor tank 1 , at point B. The displacement is carried out until the temperature of said second portion B1 of displaced liquor drops to a temperature of at least about the boiling point of said cooking liquor at atmospheric pressure. Said second portion B1 of displaced liquor will have a dry solids content substantially lower than said initial dry solids content of the cooking liquor and substantially lower than said first portion D1 of displaced liquor.
  • substantial parts of the second portion B1 of the discharged liquor in the hot black liquor tank 1 is heated by the heat of the first portion D1 of displaced liquor in the black liquor tank 2.
  • Said second portion B1 of displaced liquor is then used as hot liquor B in the pre-treatment and heating of lignocellulosic material charged to the digester.
  • the temperature of the hot liquor B is preferably adjusted with steam before entering the digester.
  • Fresh liquor, i.e. white liquor may be added to the pre-treatment stage and/or to the heating/cooking stage in order to adjust the alkalinity of the liquor in the digester.
  • the dry solids content and the temperature of displaced liquor B1 , D1 are monitored and the received results are utilized in controlling the process.
  • the prior art processes shown in Fig. 1 and 2 displaces from the digester after completed cooking, a first portion B1 of cooking liquor at said cooking temperature to a first section, i.e. to the hot black liquor tank 1 at point B, by supplying a washing liquor E from the wash filtrate tank 6, in the process shown in Fig. 1.
  • the displacement is first carried out with a liquor E from the black liquor tank 4.
  • further displacement is carried out by supplying more washing liquor E or F from the wash filtrate tank 6 to the digester, whereby a second portion of displaced liquor D1 is displaced to a second section, i.e. to black liquor tank 2, at point D.
  • the displacement is carried out until the temperature of said second portion D1 of displaced liquor drops to a temperature of at least about the boiling point of said cooking liquor at atmospheric pressure.
  • said first portion B1 of displaced liquor will have a dry solids content close to said initial dry solids content of cooking liquor.
  • Said second portion D1 will have a dry solids content substantially lower than said initial dry solids content and substantially lower than said first portion D1 of displaced liquor.
  • displacement of cooking liquor D1 from the digester to black liquor tank 2 is preferably continued until the dry solids content of said displaced cooking liquor D1 drops below said initial dry solids content of cooking liquor, resulting in a first portion of displaced liquor having a temperature of at least over about 85 % of the cooking temperature value in Celsius degrees and a dry solids content substantially corresponding to at least over about 85 % of the dry solids content of said cooking liquor.
  • the first portion of displaced liquor D1 , D2, having a high dry solids content is prevented from being reused in the digester. Instead the displaced liquor D in the hot liquor tank 2, having a high dry solids content, will be conducted through heat recovery equipments to a chemical recovery plant, i.e. an evaporation plant.
  • a chemical recovery plant i.e. an evaporation plant.
  • said first portion of displaced liquor D is used to heat the second portion of displaced liquor B1 , B2, i.e. B fed to the hot black liquor tank 1.
  • the liquor D having high dry solids content is used to heat white liquor from recovery of cooking chemicals. Further said liquor D is used to heat water.
  • the temperature of the second portion of displaced liquor B, which has preliminary been heated by the first portion of displaced liquor D, will still be adjusted by steam before said liquor B is introduced into the digester. Further the alkalinity of said second portion of displaced liquor, i.e. liquor B is adjusted by fresh alkali, i.e. white liquor C, before said liquor B is introduced into the digester. Said adjustment of alkalinity is preferably carried out in a line from the hot black liquid tank 1 to the digester.
  • the gas space of the first section, i.e. section 2 of the hot black liquor tank communicates with the second section, i.e. section 1 of said hot black liquor tank. Due to this released steam from said first section 2 heats the liquor in said second section 1 and simultaneously the liquor B will be diluted while the dry solids content of the liquor D in said first section 2 will be increased, decreasing energy consumption in a subsequent evaporation plant. Sulphur compounds released from liquor D in the first section 2 will absorb into the liquor B in the second section 1 increasing the alkalinity of said liquor B.
  • Liquor B3 displaced from the digester during the pre-treatment is led to the second section, i.e. hot liquor tank 1 as soon as the temperature of said liquor B3 is above about 100°C and the dry solids content of said liquor B3 is at about the same level as that of the second portion of displaced liquor B and/or the dry solids content of said liquor B3 is below that of the first portion of displaced liquor D.
  • said second section 1 is divided into a plurality of subsections (not shown) containing liquors of various dry solids content. Substantial parts of the liquors in said subsections of second section are used as hot liquor B in the pre-treatment, such that the order of addition to the digester system is from highest to lowest dry solids content.
  • the second section 1 and its subsections are preferably provided with mixing or other similar arrangement resulting in uniform composition and properties of the liquor B.
  • the dry solids content of the wash filtrate F is lower than that of the initial cooking liquor, said first portion of displaced liquor D and said second portion of displaced liquor B.
  • the idea is that the dry solids content of the liquors added to the digester during a digesting sequence is gradually lowered in each subsequent charge of liquor to the digester in order to keep the total dry solids content in the digester substantially constant, and especially to prevent build up of dry solids in the digester system.
  • the temperature of the washing filtrate F is below the boiling point of said washing liquid, preferably about 85 to 50°C.
  • the Examples show how the new process according to the invention will decrease the dry solids content in the liquors using alkaline cooking with a yield of 46 % and oxygen delignification with a yield of 97 %, as well as during washing with dilution factor (DF) with water and different washing efficiency values according to the E10-factor.
  • DF dilution factor
  • the dry solids content in the liquor is decreased from 23.4 % to 19.1 - 18.8 % when a method according to the invention is used.
  • hot black liquor B the dry solids content will decrease from 21.2 % to 14.1 - 13.7 % and in the wash filtrate from 12.7 % to 10.9 - 10.3.
  • the dry solids content of the impregnation liquor will decrease from 17.3 % to 10.9 - 10.3 %.
  • the dry solids content of all liquors will decrease considerably by using a method according to the present invention. This can be achieved without significantly affecting the steam consumption.
  • the advantage of the invention is, that the pulp washing efficiency is improved considerably because the amount of dissolved substances in the pulp leaving the digester is considerably lower. This is clearly indicated by the fact that the dry solids content of the wash filtrate is considerably lower. This decrease of dry solids content leads for instance to considerably easier soaking of released material from the cooked ships and the fibres. For instance in cooking extractive containing wood this enables a considerably increased solubility of difficultly soluble extractive matters. This decrease in dry solids content makes the dewatering and washing of the pulp considerably easier, and the amount of required anti foaming agent to be used will decrease remarkably.
  • the share of unwished unoxidized material from the cooking in the inlet to the oxygen delignification stage is also considerably smaller, especially using a pulp washing equipment with lower E10-values, cf. for instance Example 1 and Example 3. Further it may be assumed that the average E10-value will be improved by a specific pulp washing equipment in using a method according to the invention. This will further decrease wash loss of unoxzidized COD in the inlet to the oxygen delignificaton stage, cf. for instance Example 1 (prior art ) and Example 5.
  • the decreased dry solids content of the spent liquors in the cooking will improve and simplify bleaching of the cooked pulp, which has been experienced especially in pilot plant cooking of hardwood.
  • This decreased dry solids content may also be used as a means to decrease the amount of fresh white liquor in the digesting room.
  • Example 9 is an example of a method without using liquid/liquid heat exchangers. As will be seen from the table the steam consumption for such a process is considerably higher.
  • Impregnation liguor (A) ⁇ %-L 17,3 17,3 10,8 10,9 10,3 10,3 11 ,7 10,9

Landscapes

  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Paper (AREA)

Abstract

L'invention concerne un procédé de production de pâte dans un processus de digestion alcaline, comprenant les étapes suivantes consistant : à charger de la matière lignocellulosique dans un système de lessiveur ; à pré-traiter ladite matière lignocellulosique au moyen d'une liqueur d'imprégnation et ultérieurement au moyen d'une liqueur plus chaude contenant de la liqueur noire, déplaçant simultanément la liqueur résiduaire ; à chauffer et à cuire ladite matière lignocellulosique de sorte à produire de la matière lignocellulosique cuite et de la liqueur de cuisson ; à déplacer une partie de ladite liqueur de cuisson à température de cuisson, à partir dudit lessiveur jusqu'à une première section, par fourniture d'un liquide de lavage ; à déplacer également une deuxième partie de la liqueur déplacée à partir dudit système de lessiveur jusqu'à au moins une deuxième section, également par fourniture de liquide de lavage jusqu'à ce que la température de ladite deuxième partie de la liqueur déplacée tombe à une température d'au moins environ le point d'ébullition de ladite liqueur de cuisson, à pression atmosphérique, ladite deuxième partie de liqueur déplacée ayant une teneur en solides sensiblement inférieure à la teneur en solides initiale de la liqueur de cuisson et sensiblement inférieure à celle de ladite première partie de liqueur déplacée. Le procédé se caractérise en ce que des parties substantielles de ladite deuxième partie de liqueur déplacée sont chauffées par la chaleur de la première partie de liqueur déplacée. Ladite première partie ayant une teneur élevée en solides ne peut pas être réutilisée dans un lessiveur et ladite deuxième partie chauffée est également utilisée comme liqueur chaude dans le pré-traitement et le chauffage de ladite matière lignocellulosique.
EP01983617A 2000-11-03 2001-10-26 Procede de cuisson au moyen de liqueur noire chaude Withdrawn EP1330572A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
FI20002421 2000-11-03
FI20002421A FI115640B (fi) 2000-11-03 2000-11-03 Kuumaa mustalipeää käyttävä keittoprosessi
PCT/FI2001/000927 WO2002036876A1 (fr) 2000-11-03 2001-10-26 Procede de cuisson au moyen de liqueur noire chaude

Publications (1)

Publication Number Publication Date
EP1330572A1 true EP1330572A1 (fr) 2003-07-30

Family

ID=8559430

Family Applications (1)

Application Number Title Priority Date Filing Date
EP01983617A Withdrawn EP1330572A1 (fr) 2000-11-03 2001-10-26 Procede de cuisson au moyen de liqueur noire chaude

Country Status (7)

Country Link
US (1) US20040079498A1 (fr)
EP (1) EP1330572A1 (fr)
AU (1) AU2002215062A1 (fr)
BR (1) BR0115122A (fr)
CA (1) CA2425381A1 (fr)
FI (1) FI115640B (fr)
WO (1) WO2002036876A1 (fr)

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE518993E (sv) * 2002-01-24 2013-04-23 Metso Paper Sweden Ab Framställning av cellulosamassa genom kokning med en kokvätska innehållande förindunstad svartlut
US7604711B2 (en) * 2005-03-08 2009-10-20 Bianchini Craig A Method to optimize temperature profiles displacement batch cooking
CN103003487B (zh) * 2010-05-04 2016-04-27 巴伊亚特种纤维素公司 高α溶解浆生产的方法和系统
AU2010202496B2 (en) * 2010-05-04 2015-04-16 Bahia Specialty Cellulose Sa Method and system for high alpha dissolving pulp production
KR20110123184A (ko) 2010-05-06 2011-11-14 바히아 스페셜티 셀룰로스 에스에이 높은 알파 용해 펄프 제조를 위한 방법 및 시스템
US8709204B1 (en) * 2013-03-14 2014-04-29 Veolia Water Solutions & Technologies North America Inc. System and process for recovering heat from weak black liquor in a wood pulping process
WO2016058098A1 (fr) 2014-10-15 2016-04-21 Canfor Pulp Ltd Usine de pâte kraft intégrée et système de conversion thermochimique
SE538454C2 (en) * 2014-11-27 2016-07-12 Valmet Oy Method for displacement in batch digesters

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4578149A (en) * 1981-03-05 1986-03-25 Fagerlund Bertil K E Process for digesting cellulosic material with heat recovery
FI92224C (fi) * 1991-06-28 1994-10-10 Sunds Defibrator Rauma Oy Eräprosessi kraftmassan valmistamiseksi
FI94445C (fi) * 1992-07-10 1995-09-11 Ahlstroem Oy Menetelmä ja laite mustalipeän käsittelemiseksi
US5522958A (en) * 1994-07-18 1996-06-04 Pulp And Paper Research Institute Of Canada Two-stage kraft cooking
FI970254A (fi) * 1997-01-22 1998-07-23 Ahlstrom Machinery Oy Menetelmä ja laitteisto massan keittämiseksi

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO0236876A1 *

Also Published As

Publication number Publication date
FI20002421A0 (fi) 2000-11-03
BR0115122A (pt) 2003-09-30
FI20002421A (fi) 2002-05-04
CA2425381A1 (fr) 2002-05-10
US20040079498A1 (en) 2004-04-29
FI115640B (fi) 2005-06-15
AU2002215062A1 (en) 2002-05-15
WO2002036876A1 (fr) 2002-05-10

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