EP1528149A1 - Verfahren zur Niederkonsistenz-Sauerstoffdelignifizierung - Google Patents

Verfahren zur Niederkonsistenz-Sauerstoffdelignifizierung Download PDF

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Publication number
EP1528149A1
EP1528149A1 EP04256503A EP04256503A EP1528149A1 EP 1528149 A1 EP1528149 A1 EP 1528149A1 EP 04256503 A EP04256503 A EP 04256503A EP 04256503 A EP04256503 A EP 04256503A EP 1528149 A1 EP1528149 A1 EP 1528149A1
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EP
European Patent Office
Prior art keywords
pulp
slurry
oxygen
delignification
black liquor
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.)
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Application number
EP04256503A
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English (en)
French (fr)
Inventor
Joseph Richard Donovan
George Adusei
Neeraj Saxena
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.)
Messer LLC
Original Assignee
BOC Group Inc
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Filing date
Publication date
Application filed by BOC Group Inc filed Critical BOC Group Inc
Publication of EP1528149A1 publication Critical patent/EP1528149A1/de
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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
    • 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
    • D21C9/147—Bleaching ; Apparatus therefor with oxygen or its allotropic modifications

Definitions

  • the present invention relates to a method for delignifying softwood or hardwood pulp in a slurry at low consistency using a reaction device and oxygen.
  • Oxygen delignification of cellulosic material is generally practised at a region of medium consistency (8 to 16%).
  • partially delignified pulp is reacted with oxygen in the presence of alkali ( pH > 11) using high shear mixers and pressurized upflow reactors with retention times of 20 to 60 minutes at pressure in excess of 90 psi (6 bar) and temperatures as high as 110° C.
  • the high shear mixers facilitate the contacting of the pulp slurry with the oxygen containing gas in a very turbulent state lasting a few seconds prior to entering the pressurized vessels.
  • a method of delignifying pulp in a slurry from a fiber line of a papermaking system comprising drawing said slurry from said papermaking system, adding oxygen to said slurry and mixing said slurry under conditions of temperature and pressure whereby said oxygen reacts with the lignin present in said pulp, characterised in that the pulp is delignified at a consistency of less than 8% by weight of cellulosic material.
  • the pulp may be a softwood or hard wood pulp
  • reaction system comprising an efficient mixer and contact tank.
  • pulp is removed from the brownstock processing section between the blow tank and the bleach section of the papermaking system.
  • the reaction system is preferably physically located after (downstream of) the knotters and before (upstream of) the brown stock washers to make effective use of the residual alkali and heat content in the incoming black liquor.
  • the physical location of the reaction system can be at a convenient position along the papermaking system.
  • the location from which the low consistency pulp is taken for delignification may be one at which the pulp has an elevated temperature and an alkaline pH, thereby enabling the consumption of external energy and alkali to be kept down.
  • low consistency is defined as that pulp containing less than 8% by weight of cellulosic material.
  • the reaction system may also be physically located and the pulp slurry drawn from the section of the fiber line after (downstream of) the digester and before (upstream of) the brown stock washers , or in between any two stages of a multi-stage brownstock washing step.
  • the hot pulp slurry may be taken from the knotters with black liquor still present.
  • the black liquor results from cooking pulpwood in an aqueous solution.
  • Steam may be added to heat the slurry as well as caustic which can be used to adjust the pH.
  • oxygen is injected into the mixture which is then sent to the gas-liquid mixer.
  • the pulp slurry containing the oxygen is mixed at conditions of temperature and pressure whereby the oxygen begins to react with the lignin to effect delignification.
  • This reaction mixture is then sent from the mixer to a retention tank which is also capable of being kept at pressure, where the delignification reaction will continue further.
  • the reaction products are then sent into a blow tank or a gas-liquid separator where reaction gases and unused oxygen gas is disengaged or removed from the liquid product and scrubbed and either vented to the atmosphere or recycled.
  • the method according to the invention may be implemented as a retrofit in existing mills as well as new ones at relatively low capital cost.
  • the method according to the invention can take advantage of the residual caustic and heat that will be present in the slurry as it leaves the knotters. Furthermore a low consistency oxygen delignification reaction is easier to control compared to operations at medium and high consistencies of pulp. Accordingly low consistency oxygen delignification before the brown stock washers of a fiber line can be achieved.
  • the reactor assembly typically consists of a controlled cavitation device or other efficient mixing device, coupled with a residence tank.
  • the heat and alkali requirements for the delignification reaction are typically obtained primarily from the residual alkali and heat content in the incoming black liquor and oxygen containing gas.
  • An excess of oxygen over that required for delignification purposes can be supplied so as to react with some of the organic acids in the black liquor to reduce the heat value of the black liquor, and to react with sulfur compounds in the black liquor to reduce or eliminate the potential for total reduced sulfur (TRS) emissions.
  • TRS total reduced sulfur
  • a further advantage of the present invention is that un-oxidized white liquor can be employed as the source of needed alkali. Additionally the excess oxygen can be employed to oxidize some of the sulfur compounds in the white liquor.
  • the pulp slurry preferably has a consistency of between 2 to 8% by weight.
  • a small amount of caustic is preferably added to bring the slurry pH to at least 11 to 12.
  • steam is preferably addedto bring slurry temperature to between 85° C to 120° C.
  • the reaction mixture is preferably sent to a disengagement tank where the reaction gases are separated from the slurry and sent for treatment and disposal.
  • the delignified slurry is preferably sent to the next stage in the bleach line of the papermaking process, which could be the screens or brown stock washers.
  • pulp slurry taken from the knotters (not shown) of a papermaking plant is contacted with oxygen in the presence of caustic, under conditions of temperature and residence time (normally short) in a retention tank that enable the oxygen to react with and delignify the pulp.
  • the oxygen also reacts with the organic solid in the black liquor resulting in a reduction of the heat value of the black liquor going to the recovery boiler. Additional reactions take place between the oxygen and sulfur compounds in the liquor, thus reducing or eliminating potential sources of total reduced sulfur (TRS) emissions by the pulp mill.
  • TRS total reduced sulfur
  • Pulp slurry from the knotters (with the black liquor still present) at a consistency of between 2 to 8% is transferred by a pump 30 through pipelines 10 and 40 to a steam mixer 50.
  • Caustic if needed, may be added to the pulp slurry through side pipe 20 to maintain the pH of the pulp slurry between 11 and 12.
  • steam is added to the pulp slurry through pipe line 130 to bring the temperature of the slurry to between 90 and 110° C before it flows into the efficient mixing device which can be a cavitation type reactor 70 through line 60.
  • Oxygen containing gas is introduced through a side inlet 140 and enters the efficient mixing device with the pulp slurry stream.
  • the pulp slurry and the oxygen containing gas are brought into intimate contact by the shearing and cavitation and mechanical forces generated as the rotor rotates at a high speed in the mixing device 70.
  • the contacting is performed under suitable conditions of temperature and pressure whereby the oxygen begins to react with the lignin under caustic conditions to effect delignification.
  • the reaction mixture proceeds through pipe line 80 into a retention tank 90 where under conditions of temperature, pressure and time the delignification reaction is continued further.
  • an oxygen containing gas is used.
  • oxygen with a minimum purity of 93% is employed.
  • the preferred total reaction pressure should be not less than 80 psig and more preferably above 90 psig.
  • the preferred minimum reaction temperature is 90° C but the temperautre can typically be as high as 110° C.
  • the residence time of the reaction mixture in the retention tank is not less than 10 minutes but preferably up to 30 minutes.
  • the reaction mixture is withdrawn through outlet 100 into a blow tank or gas-liquid separator 110 where reaction gases and unused oxygen gas disengages from the liquid product and is scrubbed and vented.
  • the pulp slurry is withdrawn through line 120 and sent to the washing stage of the bleach line of the pulp and papermaking process.
  • bleaching can be done with much less capital, specifically by not having to build, own, operate and maintain separate pressure towers for traditional oxygen delignification.
  • Unoxidized white liquor can be used as the source of caustic as the oxidation of the white liquor also takes place in the mixer.
  • the exothermic heat of reaction of oxidation of white liquor raises the temperature of the pulp resulting in steam savings for oxygen delignification and most of the oxygen delignification reactions can be done at the existing pulp temperature.
  • Oxygen delignification before the brown stock washers lowers the BTU value of the black liquor allowing for increased capacity of steam limited recovery boilers. Additionally, less oxidized white liquor will be needed in this sequence than traditional two stage oxygen delignification thus taking the load off the lime kiln and other white liquor systems.
  • the black liquor produced will have a lower viscosity because of the reaction of the oxygen with the Na 2 S and a portion of the dissolved lignin allowing for a higher percentage solids firing in the recovery boiler.
  • Methanol and other alcohols present in the black liquor upstream of the brown stock washers will react to form a reducing environment in the pulp.
  • pulp strength may increase.
  • Pure oxygen was added to the slurry through a side pipe 140 at a rate of 60 pounds per hour before it entered a high efficiency gas-liquid mixer, in this case a controlled cavitation reactor 70.
  • the slurry and gas were mixed for a few seconds at about 90 pounds per square inch (psi) in the reactor 70, the stock was transferred into a retention tank 90 and kept for 10 minutes and was finally returned to the bleach line just before the first BS washer.
  • the pulp Kappa # is the amount of lignin in the pulp sample. Samples were taken from the exit slurry stream for analysis.

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Wood Science & Technology (AREA)
  • Paper (AREA)
EP04256503A 2003-10-28 2004-10-22 Verfahren zur Niederkonsistenz-Sauerstoffdelignifizierung Withdrawn EP1528149A1 (de)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US898101 2001-07-03
US51494603P 2003-10-28 2003-10-28
US514946P 2003-10-28
US10/898,101 US20050087315A1 (en) 2003-10-28 2004-07-23 Low consistency oxygen delignification process

Publications (1)

Publication Number Publication Date
EP1528149A1 true EP1528149A1 (de) 2005-05-04

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EP04256503A Withdrawn EP1528149A1 (de) 2003-10-28 2004-10-22 Verfahren zur Niederkonsistenz-Sauerstoffdelignifizierung

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US (1) US20050087315A1 (de)
EP (1) EP1528149A1 (de)
AU (1) AU2004222766A1 (de)
CA (1) CA2484557A1 (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016001755A1 (en) * 2014-07-03 2016-01-07 Linde Aktiengesellschaft Methods for the oxygen-based delignification of pulp
DE102020002445A1 (de) 2020-04-23 2021-10-28 Messer Austria Gmbh Verfahren und Vorrichtung zur Herstellung von gebleichtem Zellstoff
US12410557B2 (en) 2020-04-23 2025-09-09 Messer Austria Gmbh Process and apparatus for white liquor oxidation

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050150618A1 (en) * 2000-05-17 2005-07-14 Bijan Kazem Methods of processing lignocellulosic pulp with cavitation
US20050067122A1 (en) * 2000-05-17 2005-03-31 Bijan Kazem Methods of processing lignocellulosic pulp with cavitation
US7507014B1 (en) 2005-08-05 2009-03-24 Hydro Dynamics, Inc. Controlled cavitation device with easy disassembly and cleaning
US20080167204A1 (en) * 2007-01-09 2008-07-10 Billy Ray Slabaugh Process for Enhancing Fluid Hydration
WO2008089321A2 (en) * 2007-01-17 2008-07-24 Joe Mccall Apparatus and methods for production of biodiesel
US20080268302A1 (en) * 2007-01-17 2008-10-30 Mccall Joe Energy production systems and methods
AU2021264520B2 (en) 2020-04-30 2025-05-22 Hydro Dynamics, Inc. System and method for treatment of plants for synthesis of compounds therefrom

Citations (9)

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US4248662A (en) 1979-01-22 1981-02-03 The Black Clawson Company Oxygen pulping with recycled liquor
US4294654A (en) 1980-03-21 1981-10-13 International Paper Company Delignification and bleaching of lignocellulosic pulp via photo-oxygenation
CA1186106A (en) * 1981-11-02 1985-04-30 Edward F. Elton Process and apparatus for the oxygen delignification of pulp
US4626319A (en) 1984-08-01 1986-12-02 Degussa Aktiengesellschaft Process for the delignification and acid bleaching of cellulose with oxygen and hydrogen peroxide
WO1988006201A1 (en) * 1987-02-12 1988-08-25 Sigurd Fongen Process for production of cellulose pulp and/or delignification of secondary fibers
US4834837A (en) 1984-06-27 1989-05-30 Waagner-Biro Aktiengessellschaft Method for delignification of cellulose with oxygen
WO1989012716A1 (en) * 1988-06-24 1989-12-28 Sigurd Fongen Process and apparatus for the manufacture of pulp for paper, board, fiberboard and similar products
US5352332A (en) * 1991-01-28 1994-10-04 Maples Gerald E Process for recycling bleach plant filtrate
EP0641883A2 (de) * 1993-08-12 1995-03-08 The Boc Group, Inc. Verfahren zur Delignifizierung mittels Sauerstoff

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US4946556A (en) * 1989-04-25 1990-08-07 Kamyr, Inc. Method of oxygen delignifying wood pulp with between stage washing
FI92725C (fi) * 1991-09-09 1994-12-27 Ahlstroem Oy Menetelmä keittolipeän valmistamiseksi
US5690786A (en) * 1991-11-26 1997-11-25 Air Products And Chemicals Inc. Process for the treatment of pulp with oxygen and steam using ejectors
US5439556A (en) * 1993-08-16 1995-08-08 The Boc Group, Inc. Oxidation of white liquor using a packing column
FR2719854B1 (fr) * 1994-05-11 1996-06-21 Atochem Elf Sa Procédé de préparation de pâtes à papier chimiques délignifiées et blanchies.
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SE505141C2 (sv) * 1995-10-23 1997-06-30 Sunds Defibrator Ind Ab Syrgasdelignifiering av massa i två steg med hög satsning av alkali och syrgas och temperatur under 90 C i första steget
US20050067122A1 (en) * 2000-05-17 2005-03-31 Bijan Kazem Methods of processing lignocellulosic pulp with cavitation
US6627784B2 (en) * 2000-05-17 2003-09-30 Hydro Dynamics, Inc. Highly efficient method of mixing dissimilar fluids using mechanically induced cavitation
US20050150618A1 (en) * 2000-05-17 2005-07-14 Bijan Kazem Methods of processing lignocellulosic pulp with cavitation
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Publication number Priority date Publication date Assignee Title
US4248662A (en) 1979-01-22 1981-02-03 The Black Clawson Company Oxygen pulping with recycled liquor
US4294654A (en) 1980-03-21 1981-10-13 International Paper Company Delignification and bleaching of lignocellulosic pulp via photo-oxygenation
CA1186106A (en) * 1981-11-02 1985-04-30 Edward F. Elton Process and apparatus for the oxygen delignification of pulp
US4834837A (en) 1984-06-27 1989-05-30 Waagner-Biro Aktiengessellschaft Method for delignification of cellulose with oxygen
US4626319A (en) 1984-08-01 1986-12-02 Degussa Aktiengesellschaft Process for the delignification and acid bleaching of cellulose with oxygen and hydrogen peroxide
WO1988006201A1 (en) * 1987-02-12 1988-08-25 Sigurd Fongen Process for production of cellulose pulp and/or delignification of secondary fibers
WO1989012716A1 (en) * 1988-06-24 1989-12-28 Sigurd Fongen Process and apparatus for the manufacture of pulp for paper, board, fiberboard and similar products
US5352332A (en) * 1991-01-28 1994-10-04 Maples Gerald E Process for recycling bleach plant filtrate
EP0641883A2 (de) * 1993-08-12 1995-03-08 The Boc Group, Inc. Verfahren zur Delignifizierung mittels Sauerstoff

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016001755A1 (en) * 2014-07-03 2016-01-07 Linde Aktiengesellschaft Methods for the oxygen-based delignification of pulp
DE102020002445A1 (de) 2020-04-23 2021-10-28 Messer Austria Gmbh Verfahren und Vorrichtung zur Herstellung von gebleichtem Zellstoff
WO2021213740A1 (de) 2020-04-23 2021-10-28 Messer Austria Gmbh Verfahren und vorrichtung zur herstellung von gebleichtem zellstoff
US12410557B2 (en) 2020-04-23 2025-09-09 Messer Austria Gmbh Process and apparatus for white liquor oxidation
US12559885B2 (en) 2020-04-23 2026-02-24 Messer Austria Gmbh Process and apparatus for producing bleached cellulose

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Publication number Publication date
US20050087315A1 (en) 2005-04-28
AU2004222766A1 (en) 2005-05-12
CA2484557A1 (en) 2005-04-28

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