EP4428297A1 - Verfahren zur gewinnung von vollständig oxidierter weisslauge zur verwendung in der faserlinie eines kraftzellstoffverfahrens - Google Patents
Verfahren zur gewinnung von vollständig oxidierter weisslauge zur verwendung in der faserlinie eines kraftzellstoffverfahrens Download PDFInfo
- Publication number
- EP4428297A1 EP4428297A1 EP23160197.2A EP23160197A EP4428297A1 EP 4428297 A1 EP4428297 A1 EP 4428297A1 EP 23160197 A EP23160197 A EP 23160197A EP 4428297 A1 EP4428297 A1 EP 4428297A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- stages
- white liquor
- kraft pulp
- oxygen
- fully oxidized
- 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.)
- Pending
Links
- 238000000034 method Methods 0.000 title claims abstract description 92
- 239000002655 kraft paper Substances 0.000 title claims abstract description 39
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims abstract description 99
- 239000000706 filtrate Substances 0.000 claims abstract description 19
- 238000010926 purge Methods 0.000 claims abstract description 17
- 238000004065 wastewater treatment Methods 0.000 claims abstract description 7
- 238000004061 bleaching Methods 0.000 claims description 28
- 238000011084 recovery Methods 0.000 claims description 23
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 20
- 229910052760 oxygen Inorganic materials 0.000 claims description 20
- 239000001301 oxygen Substances 0.000 claims description 20
- 238000000605 extraction Methods 0.000 claims description 18
- 238000005406 washing Methods 0.000 claims description 13
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 10
- 230000003647 oxidation Effects 0.000 claims description 10
- 238000007254 oxidation reaction Methods 0.000 claims description 10
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 claims description 9
- 238000001704 evaporation Methods 0.000 claims description 9
- 230000008020 evaporation Effects 0.000 claims description 9
- 230000001590 oxidative effect Effects 0.000 claims description 9
- 229910052938 sodium sulfate Inorganic materials 0.000 claims description 9
- AKHNMLFCWUSKQB-UHFFFAOYSA-L sodium thiosulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=S AKHNMLFCWUSKQB-UHFFFAOYSA-L 0.000 claims description 9
- 239000007832 Na2SO4 Substances 0.000 claims description 8
- 239000007789 gas Substances 0.000 claims description 8
- 239000000126 substance Substances 0.000 claims description 8
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 claims description 5
- 239000000203 mixture Substances 0.000 claims description 5
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 5
- 239000011734 sodium Substances 0.000 description 8
- 229910052708 sodium Inorganic materials 0.000 description 8
- 241000196324 Embryophyta Species 0.000 description 7
- 229910052717 sulfur Inorganic materials 0.000 description 7
- 238000006243 chemical reaction Methods 0.000 description 6
- 239000007788 liquid Substances 0.000 description 5
- 239000000243 solution Substances 0.000 description 5
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 4
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 3
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 239000002023 wood Substances 0.000 description 3
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 2
- 238000013459 approach Methods 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 238000004587 chromatography analysis Methods 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- -1 sulfide ions Chemical class 0.000 description 2
- 239000011593 sulfur Substances 0.000 description 2
- 229920003043 Cellulose fiber Polymers 0.000 description 1
- 229920001131 Pulp (paper) Polymers 0.000 description 1
- 241000220317 Rosa Species 0.000 description 1
- 239000005864 Sulphur Substances 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 230000000740 bleeding effect Effects 0.000 description 1
- 229920002678 cellulose Polymers 0.000 description 1
- 239000001913 cellulose Substances 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 230000029087 digestion Effects 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- VDQVEACBQKUUSU-UHFFFAOYSA-M disodium;sulfanide Chemical compound [Na+].[Na+].[SH-] VDQVEACBQKUUSU-UHFFFAOYSA-M 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 210000003734 kidney Anatomy 0.000 description 1
- 238000002386 leaching Methods 0.000 description 1
- 229920005610 lignin Polymers 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000006385 ozonation reaction Methods 0.000 description 1
- 238000004537 pulping Methods 0.000 description 1
- 235000011152 sodium sulphate Nutrition 0.000 description 1
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
- D21C11/00—Regeneration of pulp liquors or effluent waste waters
- D21C11/0064—Aspects concerning the production and the treatment of green and white liquors, e.g. causticizing green liquor
- D21C11/0071—Treatment of green or white liquors with gases, e.g. with carbon dioxide for carbonation; Expulsion of gaseous compounds, e.g. hydrogen sulfide, from these liquors by this treatment (stripping); Optional separation of solid compounds formed in the liquors by this treatment
-
- 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
- D21C3/022—Pulping cellulose-containing materials with inorganic bases or alkaline reacting compounds, e.g. sulfate processes in presence of S-containing compounds
-
- 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
- D21C11/12—Combustion of pulp liquors
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/10—Bleaching ; Apparatus therefor
Definitions
- This application relates to a process to obtain fully oxidized white liquor comprising NaOH, Na 2 SO 4 , NaCO 3 , and traces of Na 2 S 2 O 3 for use in the fiberline of a Kraft pulp process.
- the Kraft process is a process for the conversion of wood into wood pulp consisting of almost pure cellulose fibers. It entails treatment of wood chips with a mixture of sodium hydroxide (NaOH) and sodium sulfide (Na 2 S), known as white liquor, which breaks the bonds that link lignin to the cellulose.
- NaOH sodium hydroxide
- Na 2 S sodium sulfide
- EP1345684B1 discloses a method for oxidizing a liquid contained in a reactor (1) that comprises means for introducing gas into the reactor and means for introducing liquid into the reactor, at least liquid evacuating means, at least gas evacuating means.
- the liquid contains compounds to be oxidized and the oxidizing gas contains oxygen, where gas roof bleeding provides a predetermined partial pressure of the oxygen in the gaseous roof, the value of said partial pressure corresponding to a desired oxidizing rate for said compounds.
- EP1345680B1 discloses an oxidizing method by wet process oxidation or ozonization of a liquid contained in a reactor.
- the method is more particularly suitable for all oxidizing processes using large amounts of oxygen or ozone. It is in particular used for oxidizing paper-mill liquors.
- the present application relates to a process to obtain fully oxidized white liquor for use in the fiberline of a Kraft pulp process comprising the following steps:
- the white liquor is oxidized with 20 to 60 kg of O 2 /m 3 of white liquor.
- the oxygen is used as pure oxygen or as a gas mixture comprising oxygen.
- oxygen is used with a purity degree above 70% v/v.
- the fully oxidized white liquor substitutes up to 100% of the amount of purchased NaOH used in the bleaching stages and/or alkaline extraction stages and/or delignification stages of the Kraft pulp process.
- the oxidation step occurs at a temperature above 100°C, pressure above 1 barg, and the total Hydraulic Residence Time is at least 30 minutes.
- up to 100% of the filtrates from washing steps after the bleaching stages and/or alkaline extraction stages are sent to the Wastewater Treatment Plant.
- Companies in this technical field can benefit from a reduction of the high cost related to purchased NaOH by reusing process streams currently present in the Kraft pulp process to produce a solution comprising NaOH which can be used as a substitute for the pure product.
- the present application relates to a process to obtain said solution, known as fully oxidized white liquor (FOWL), which comprises NaOH, Na 2 SO 4 , NaCO 3 and traces of Na 2 S 2 O 3 .
- FOWL fully oxidized white liquor
- the FOWL is obtained from the white liquor used in a Kraft pulp process.
- the aim of this process is to produce a solution suitable to substitute purchased NaOH used in the alkaline steps of certain stages in the fiberline, such as the delignification stages and/or alkaline extraction stages and/or bleaching stages that use NaOH in certain steps, as well as purge non-process elements from the recovery circuit of the kraft pulp process by purging alkaline wash filtrates to a Wastewater Treatment Plant (WWTP).
- WWTP Wastewater Treatment Plant
- the FOWL produced by the presently disclosed process is also suitable to be used in bleaching stages that use hydrogen peroxide.
- the oxygen used in the present process can be not only pure oxygen but also impure oxygen with purity > 70% O 2 v/v.
- This impure oxygen can be produced in a PSA or VSA unit, but also can be the off-gas of an Ozone bleaching stage, which normally is above 700 O 2 v/v.
- reaction (I) as well as reaction (II) proceed to their full extent and the presence of sulfide ions is undetectable by Ionic Chromatography. In this case the extent of conversion of total sulfur to sulfate ions expressed as sulphur should be above 900.
- the product of this process can be called "Fully Oxidised White Liquor" and the quality is so good that it can be used as a substitute for the purchased NaOH used in the fiberline, including the stages using hydrogen peroxide, without any detectable difference from using the pure NaOH product.
- FIG. 1 shows a general schematic representation of a Kraft pulp process including one embodiment of the process disclosed in the present application.
- the present application relates to a process to obtain fully oxidized white liquor from the white liquor used in a Kraft pulp process.
- the FOWL is suitable to be used in the alkaline stages of the fiberline of said Kraft pulp process, such as the bleaching stages, and/or alkaline extraction stages and/or the delignification stages that comprise alkaline steps.
- FIG. 1 shows a general schematic representation of a Kraft pulp process comprising the process of the present application.
- (A) represents the fiberline and
- (B) represents the recovery line.
- a fraction of the white liquor (2) is fed to at least one oxidation reactor (K) to produce FOWL (5) which is used in the delignification stages (H) and/or the bleaching stages (I) and/or alkaline extraction stages to partly or totally substitute purchased NaOH used in alkaline steps of these stages.
- the resulting alkaline wash filtrate (6.1, 6.2) of the delignification stages (H) and/or bleaching stages (I) are fed back to an evaporation plant (E) in the recovery line (B) to return to the Kraft chemical recovery process (C).
- the non-process elements (7.1) will be totally or partly purged to the WWTP through the wash step after the alkaline bleaching stages (I).
- purchased NaOH is also known as fresh NaOH.
- the process to obtain fully oxidized white liquor for use in the fiberline of a Kraft pulp process comprises the following steps:
- white liquor is oxidized with 20 to 60 kg of O 2 /m 3 of white liquor.
- the amount of alkaline filtrate (6.2) obtained in the bleaching stages (I) and/or alkaline extraction stages that is fed to the evaporation plant (E) varies according to the concentration of non-process elements.
- the amount of alkaline filtrate (6.1) obtained in the delignification stages (H) that is fed to the evaporation plant (E) is 100% due to the high concentration of chemical oxygen demand (COD).
- up to 100% of the fully oxidized white liquor (5) is fed to the bleaching stages (I) and/or alkaline extraction stages and/or the delignification stages (H).
- oxygen is used in the process as pure oxygen or as a gas mixture comprising oxygen.
- pure oxygen is considered an oxygen stream with a purity degree above 700 O 2 v/v.
- the FOWL totally or partially substitutes up to 100% of the amount of purchased NaOH used in the delignification stages of the Kraft pulp process.
- the FOWL substitutes up to 100% of the amount of purchased NaOH used in the bleaching stages and/or alkaline extraction stages of the Kraft pulp process.
- the oxidation step of the process makes use of at least one oxidation reactor (K) .
- a plurality of reactors can be used for the purpose of the present invention.
- the FOWL produced is an aqueous solution comprising NaOH, Na 2 SO 4 , NaCO 3 and less than 5 g of Na 2 S 2 O 3 per liter of FOWL, in which the presence of sulfide ions is undetectable by Ionic Chromatography and the extent of conversion of total sulfur to sulfate ions is above 900.
- the temperature is above 100°C
- the pressure is above 1 barg
- the total Hydraulic Residence Time (HRT) is at least 30 minutes.
- the sodium makeup of the recovery line of the Kraft pulp process is done - solely or in part, i.e., up to 1000, - in the delignification stages (H) by using purchased NaOH.
- the sodium makeup of the recovery line of the Kraft pulp process is done - solely or in part - in the recovery boiler (F) as Na 2 CO 3 and/or Na 2 SO 4 .
- the non-process elements such as K + or Cl - but not exclusively, are purged from the recovery line through the use of the FOWL.
- the totality or a fraction, i.e., up to 100% of the filtrates from washing steps after the bleaching stages and/or alkaline extraction stages are sent to the WWTP - thus discharging the recovery line from non-process elements.
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- Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Wood Science & Technology (AREA)
- Paper (AREA)
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP23160197.2A EP4428297A1 (de) | 2023-03-06 | 2023-03-06 | Verfahren zur gewinnung von vollständig oxidierter weisslauge zur verwendung in der faserlinie eines kraftzellstoffverfahrens |
| US18/597,787 US20240301622A1 (en) | 2023-03-06 | 2024-03-06 | Process to obtain fully oxidized white liquor for use in the fiberline of a kraft pulp process |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP23160197.2A EP4428297A1 (de) | 2023-03-06 | 2023-03-06 | Verfahren zur gewinnung von vollständig oxidierter weisslauge zur verwendung in der faserlinie eines kraftzellstoffverfahrens |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| EP4428297A1 true EP4428297A1 (de) | 2024-09-11 |
Family
ID=85505523
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP23160197.2A Pending EP4428297A1 (de) | 2023-03-06 | 2023-03-06 | Verfahren zur gewinnung von vollständig oxidierter weisslauge zur verwendung in der faserlinie eines kraftzellstoffverfahrens |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US20240301622A1 (de) |
| EP (1) | EP4428297A1 (de) |
Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA1043516A (en) * | 1973-07-25 | 1978-12-05 | Mo Och Domsjo Aktiebolag | Method for producing oxidized white liquor |
| EP0543135A1 (de) * | 1991-10-18 | 1993-05-26 | Air Products And Chemicals, Inc. | Selektive Oxydation von Weisslauge |
| US5352332A (en) * | 1991-01-28 | 1994-10-04 | Maples Gerald E | Process for recycling bleach plant filtrate |
| EP0643163A2 (de) * | 1993-08-16 | 1995-03-15 | The Boc Group, Inc. | Verfahren zur Herstellung von oxydierter Weisslauge |
| WO2000047812A1 (en) * | 1999-02-15 | 2000-08-17 | Kiram Ab | Process for oxygen pulping of lignocellulosic material and recovery of pulping chemicals |
| EP1345680B1 (de) | 2000-12-20 | 2004-10-27 | L'AIR LIQUIDE, Société Anonyme à Directoire et Conseil de Surveillance pour l'Etude et l'Exploitation des | nassoxydations- oder ozonierungsverfahren |
| EP1345684B1 (de) | 2000-12-20 | 2012-05-09 | L'AIR LIQUIDE, Société Anonyme pour l'Etude et l'Exploitation des Procédés Georges Claude | Verbesserungen bei oxidationsverfahren durch sauerstofftransfer in einem flüssigen medium in einem reaktor unter druck |
| WO2020165504A1 (en) * | 2019-02-13 | 2020-08-20 | Metsä Fibre Oy | A method of replacing sodium losses in a pulp mill, a method of producing bleached cellulosic pulp, and a system |
| WO2021006798A1 (en) * | 2019-07-05 | 2021-01-14 | Kiram Ab | Method for dissolving pulp from recycled textile material |
-
2023
- 2023-03-06 EP EP23160197.2A patent/EP4428297A1/de active Pending
-
2024
- 2024-03-06 US US18/597,787 patent/US20240301622A1/en active Pending
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA1043516A (en) * | 1973-07-25 | 1978-12-05 | Mo Och Domsjo Aktiebolag | Method for producing oxidized white liquor |
| US5352332A (en) * | 1991-01-28 | 1994-10-04 | Maples Gerald E | Process for recycling bleach plant filtrate |
| EP0543135A1 (de) * | 1991-10-18 | 1993-05-26 | Air Products And Chemicals, Inc. | Selektive Oxydation von Weisslauge |
| EP0643163A2 (de) * | 1993-08-16 | 1995-03-15 | The Boc Group, Inc. | Verfahren zur Herstellung von oxydierter Weisslauge |
| WO2000047812A1 (en) * | 1999-02-15 | 2000-08-17 | Kiram Ab | Process for oxygen pulping of lignocellulosic material and recovery of pulping chemicals |
| EP1345680B1 (de) | 2000-12-20 | 2004-10-27 | L'AIR LIQUIDE, Société Anonyme à Directoire et Conseil de Surveillance pour l'Etude et l'Exploitation des | nassoxydations- oder ozonierungsverfahren |
| EP1345684B1 (de) | 2000-12-20 | 2012-05-09 | L'AIR LIQUIDE, Société Anonyme pour l'Etude et l'Exploitation des Procédés Georges Claude | Verbesserungen bei oxidationsverfahren durch sauerstofftransfer in einem flüssigen medium in einem reaktor unter druck |
| WO2020165504A1 (en) * | 2019-02-13 | 2020-08-20 | Metsä Fibre Oy | A method of replacing sodium losses in a pulp mill, a method of producing bleached cellulosic pulp, and a system |
| WO2021006798A1 (en) * | 2019-07-05 | 2021-01-14 | Kiram Ab | Method for dissolving pulp from recycled textile material |
Also Published As
| Publication number | Publication date |
|---|---|
| US20240301622A1 (en) | 2024-09-12 |
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