US20040079498A1 - Cooking process using hot black liquor - Google Patents

Cooking process using hot black liquor Download PDF

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Publication number
US20040079498A1
US20040079498A1 US10/415,771 US41577103A US2004079498A1 US 20040079498 A1 US20040079498 A1 US 20040079498A1 US 41577103 A US41577103 A US 41577103A US 2004079498 A1 US2004079498 A1 US 2004079498A1
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US
United States
Prior art keywords
liquor
displaced
cooking
solids content
dry solids
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Abandoned
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US10/415,771
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English (en)
Inventor
Hannu Haaslahti
Olavi Katajisto
Osmo Keitaaniemi
Mikael Svedman
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Valmet Technologies Oy
Victoria University of Manchester
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Individual
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Assigned to METSO PAPER, INC. reassignment METSO PAPER, INC. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: HAASLAHTI, HANNU, SVEDMAN, MIKAEL, KATAJISTO, OLAVI, KEITAANIEMI, OSMO
Publication of US20040079498A1 publication Critical patent/US20040079498A1/en
Assigned to VICTORIA UNIVERSITY OF MANCHESTER, THE reassignment VICTORIA UNIVERSITY OF MANCHESTER, THE ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: BRITTAIN, LOUISE, MATRIX THERAPEUTICS, LTD., TATE, ANDREW
Assigned to VALMET TECHNOLOGIES, INC. reassignment VALMET TECHNOLOGIES, INC. CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). Assignors: METSO PAPER, INC.
Abandoned legal-status Critical Current

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    • 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:
  • 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-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 D 1 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 FIGS. 3 - 4 , by supplying 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 B 1 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 B 1 of displaced liquor drops to a temperature of at least about the boiling point of said cooking liquor at atmospheric pressure.
  • Said second portion B 1 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 D 1 of displaced liquor.
  • substantial parts of the second portion B 1 of the discharged liquor in the hot black liquor tank 1 is heated by the heat of the first portion D 1 of displaced liquor in the black liquor tank 2 .
  • Said second portion B 1 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 prior art processes shown in FIGS. 1 and 2 displaces from the digester after completed cooking, a first portion B 1 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 D 1 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 D 1 of displaced liquor drops to a temperature of at least about the boiling point of said cooking liquor at atmospheric pressure.
  • said first portion B 1 of displaced liquor will have a dry solids content close to said initial dry solids content of cooking liquor.
  • Said second portion D 1 will have a dry solids content substantially lower than said initial dry solids content and substantially lower than said first portion D 1 of displaced liquor.
  • displacement of cooking liquor D 1 from the digester to black liquor tank 2 is preferably continued until the dry solids content of said displaced cooking liquor D 1 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 D 1 , D 2 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 B 1 , B 2 , 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 B 3 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 B 3 is above about 100° C. and the dry solids content of said liquor B 3 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 B 3 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 sub-sections 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.
  • 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. TABLE 1 Example 1 2 3 4 5 6 7 9 Steam consumption in cooking LP (kg/adt) 210 210 210 210 210 210 210 MP (kg/adt) 664 665 676 676 676 676 683 1134 Dry solids contents of cooking liquors Impregnation liquor (A) (%) 17.3 17.3 10.8 10.9 10.3 10.3 11.7 10.9 Hot black liquor (B) (%) 21.2 21.2 14.1 14.1 13.7 13.7 14.8 14.2 End-of-cook (%) 23.4 23.4 19.1 19.1 18.8 18.8 19.4 19.2 Wash filtrate (F) (%) 12.7 12.7 10.7 10.9 10.3 10.3 11.7 10.9 Evaporation black liquor (%) 16.5 16.5 16.5 16.5 16.5 17.2 16.6 Washing E10-values (washing prior 11.5 14.9 11.5 11.5 1

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  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Paper (AREA)
US10/415,771 2000-11-03 2001-10-26 Cooking process using hot black liquor Abandoned US20040079498A1 (en)

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

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US20040079498A1 true US20040079498A1 (en) 2004-04-29

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US10/415,771 Abandoned US20040079498A1 (en) 2000-11-03 2001-10-26 Cooking process using hot black liquor

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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)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050115691A1 (en) * 2002-01-24 2005-06-02 Lindstroem Mikael Cooking of cellulose pulp in a cooking liquor containing preevaporated black liquor
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
US10450701B2 (en) * 2014-10-15 2019-10-22 Licella Pty Ltd Pulping liquors and uses thereof

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7604711B2 (en) * 2005-03-08 2009-10-20 Bianchini Craig A Method to optimize temperature profiles displacement batch cooking
KR20110123184A (ko) 2010-05-06 2011-11-14 바히아 스페셜티 셀룰로스 에스에이 높은 알파 용해 펄프 제조를 위한 방법 및 시스템
PT2567022E (pt) * 2010-05-04 2014-12-23 Bahia Specialty Cellulose Sa Método e sistema para processamento de pasta utilizando extracção cáustica a frio com reutilização de filtrado alcalino
AU2010202496B2 (en) * 2010-05-04 2015-04-16 Bahia Specialty Cellulose Sa Method and system for high alpha dissolving pulp production
SE538454C2 (en) * 2014-11-27 2016-07-12 Valmet Oy Method for displacement in batch digesters

Citations (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
US5405502A (en) * 1992-07-10 1995-04-11 A. Ahlstrom Corporation Apparatus for treating black liquor
US5522958A (en) * 1994-07-18 1996-06-04 Pulp And Paper Research Institute Of Canada Two-stage kraft cooking
US5643410A (en) * 1991-06-28 1997-07-01 Sunds Defibrator Rauma Oy Batch process for preparing kraft pulp in a batch digesting process
US6350348B1 (en) * 1997-01-22 2002-02-26 Andritz-Ahlstrom Oy Batch cooking with black liquor pretreatment

Patent Citations (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
US5643410A (en) * 1991-06-28 1997-07-01 Sunds Defibrator Rauma Oy Batch process for preparing kraft pulp in a batch digesting process
US5405502A (en) * 1992-07-10 1995-04-11 A. Ahlstrom Corporation Apparatus for treating black liquor
US5522958A (en) * 1994-07-18 1996-06-04 Pulp And Paper Research Institute Of Canada Two-stage kraft cooking
US6350348B1 (en) * 1997-01-22 2002-02-26 Andritz-Ahlstrom Oy Batch cooking with black liquor pretreatment

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050115691A1 (en) * 2002-01-24 2005-06-02 Lindstroem Mikael Cooking of cellulose pulp in a cooking liquor containing preevaporated black liquor
US7351306B2 (en) * 2002-01-24 2008-04-01 Metso Fiber Karlstad Ab Cooking of cellulose pulp in a cooking liquor containing pre-evaporated black liquor
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
US10450701B2 (en) * 2014-10-15 2019-10-22 Licella Pty Ltd Pulping liquors and uses thereof
US11306435B2 (en) 2014-10-15 2022-04-19 Licella Pty Ltd. Integrated Kraft pulp mill and thermochemical conversion system
US11834783B2 (en) 2014-10-15 2023-12-05 Canfor Pulp Ltd. Integrated kraft pulp mill and thermochemical conversion system

Also Published As

Publication number Publication date
WO2002036876A1 (fr) 2002-05-10
EP1330572A1 (fr) 2003-07-30
CA2425381A1 (fr) 2002-05-10
FI115640B (fi) 2005-06-15
FI20002421A0 (fi) 2000-11-03
AU2002215062A1 (en) 2002-05-15
BR0115122A (pt) 2003-09-30
FI20002421A (fi) 2002-05-04

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AS Assignment

Owner name: METSO PAPER, INC., FINLAND

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:HAASLAHTI, HANNU;KATAJISTO, OLAVI;KEITAANIEMI, OSMO;AND OTHERS;REEL/FRAME:014620/0979;SIGNING DATES FROM 20030619 TO 20030715

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Owner name: VICTORIA UNIVERSITY OF MANCHESTER, THE, GREAT BRIT

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Effective date: 20040524

STCB Information on status: application discontinuation

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Owner name: VALMET TECHNOLOGIES, INC., FINLAND

Free format text: CHANGE OF NAME;ASSIGNOR:METSO PAPER, INC.;REEL/FRAME:032551/0426

Effective date: 20131212