EP0106460A1 - Verfahren und Vorrichtung zur Sauerstoffdelignifizierung - Google Patents

Verfahren und Vorrichtung zur Sauerstoffdelignifizierung Download PDF

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Publication number
EP0106460A1
EP0106460A1 EP83304894A EP83304894A EP0106460A1 EP 0106460 A1 EP0106460 A1 EP 0106460A1 EP 83304894 A EP83304894 A EP 83304894A EP 83304894 A EP83304894 A EP 83304894A EP 0106460 A1 EP0106460 A1 EP 0106460A1
Authority
EP
European Patent Office
Prior art keywords
oxygen
conduit
fibrous materials
materials
reaction zone
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.)
Ceased
Application number
EP83304894A
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English (en)
French (fr)
Inventor
Vincent Louis Magnotta
Larry Derwood Markham
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.)
Air Products and Chemicals Inc
Black Clawson Co
Original Assignee
Air Products and Chemicals Inc
Black Clawson Co
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 Air Products and Chemicals Inc, Black Clawson Co filed Critical Air Products and Chemicals Inc
Publication of EP0106460A1 publication Critical patent/EP0106460A1/de
Ceased legal-status Critical Current

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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
    • 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
    • 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
    • D21C9/1068—Bleaching ; Apparatus therefor with O2

Definitions

  • the present invention relates to oxygen delignification of fibrous materials, and more particularly to the oxygen delignification of medium consistency bleachable grade pulp and other fibrous materials utilizing substantially horizontal tubular reaction zones.
  • medium consistency that is 8-20% consistency.
  • Such a delignification system would be compatible with much existing mill equipment, including pulp washing and thickening equipment, since that equipment is designed to operate in a medium consistency range.
  • Delignification systems utilizing medium consistency pulp are desirable over delignification systems utilizing low consistency pulp (i.e., 1-5% consistency), since the latter require a large reactor volume to maintain an acceptable retention time for the pulp and have large power demands for pumping large volumes of pulp and for steam to heat the pulp in the reactor.
  • Delignification systems utilizing high consistency pulp i.e., 20-30% consistency
  • An efficient and relatively low-cost apparatus for performing oxygen delignification on medium consistency pulp consists of at least one but preferably two or more substantially horizontal tubular reaction zones, each having an agitating and conveying means such as a screw extending along at least a portion of its length which is driven by a motor.
  • the reaction zones have an inlet through which the pulp enters, an outlet through which the delignified pulp exits the reaction zone; and preferably include a plurality of orifices through which alkaline liquor, steam, and oxygen enter the reaction zone.
  • the screw may have a number of different configurations, but a commonly utilized screw consists of a central shaft about which extends a helical flight which acts both to agitate and convey the pulp.
  • the first horizontal reaction zone of such an apparatus typically receives the stock in a somewhat compacted form from a thick stock pump which pumps the stock through a conduit that is substantially full of the stock during the pumping operation. This is in contrast to the reaction zone which typically is operated to provide a space at the top of the zone for gas to collect along its length. As a result, a portion of the horizontal reaction zone is needed to break up the compacted pulp to expose the mass of the pulp to the oxygen so that the delignification process may be initiated. Thus, the delignification reaction is not initiated until the pulp stock has traveled a portion of the length of the reaction zone, and the screw has had an opportunity to agitate and break up the mass of pulp. Consequently, longer reaction times are required to delignify the pulp. These longer reaction times result in the need for larger, and hence more costly, reactor equipment.
  • an apparatus and process for the continuous oxygen delignification of fibrous materials including at least one substantially horizontal tubular reaction zone having an inlet and an outlet, means for agitating and transporting fibrous materials through the reaction zone to the outlet thereof, a pump for pumping fibrous materials to the reaction zone, and a conduit for conveying fibrous-materials from the pump to the inlet of the reaction zone, the conduit having means for introducing oxygen therein to initiate the delignification reaction and a motionless mixer located in the conduit for mixing the oxygen and fibrous materials.
  • the present invention provides an improved apparatus for the continuous oxygen delignification of fibrous materials such as medium consistency pulp, which utilizes one or more reaction zones, but in which the pulp stock enters the reaction zones after having been mixed with oxygen and alkaline chemicals so that the delignification process has already been initiated and the compacted state of the pulp has been diminuted.
  • This improves the rate of oxygen delignification within the reaction zones and thereby increases the efficiency of, and reduces the size and capital cost of the equipment required.
  • Another advantage of the delignification system of the present invention is that oxygen is added to the pulp mass at a point immediately adjacent-the thick stock pump, rather than in the reaction zones only, where the operating pressure is substantially greater than the operating pressure within the reaction zones.
  • the present invention will be defined and is best suited for oxygen delignification of medium consistency pulp, i.e., 8-20% consistency, it is to be understood that the apparatus may also be used for the delignification of fibrous materials of low consistency, i.e., between about 3-8%. Additionally, although the invention will be defined for use in conjunction with one or more substantially horizontal tubular reaction zones, it will be understood that other reaction vessels such as vertical towers may be utilized.
  • the present invention provides an apparatus for the continuous oxygen delignification of fibrous materials of the type having at least a first substantially horizontal tubular reaction zone having an inlet and outlet, a screw for agitating and transporting the fibrous materials through the reaction zone to the outlet, a thick stock pump for pumping the fibrous materials to the first reaction zone, and a connecting conduit for conveying the materials from the pump to the inlet of the first reaction zone.
  • the improvement consists of an oxygen supply conduit communicating with the connecting conduit for introducing oxygen into the connecting conduit and an in-line mixer mounted within the connecting conduit downstream of the oxygen supply conduit for mixing the oxygen introduced into the connecting conduit with the fibrous materials flowing to the reaction zone.
  • alkaline chemicals and/or steam are introduced into the connecting conduit to maintain an optimum pH value of the pulp solution as well as to heat it to a desirable temperature.
  • the in-line mixer that is utilized in the connecting conduit is a motionless mixer so that the energy imparted to the pulp suspension by the thick stock pump itself is used to perform the mixing operation.
  • a motionless mixer also does not create the high shear forces which are detrimental to pulp strength. Surprisingly, it has been found that adequate mixing of pulp with oxygen can be achieved using a motionless mixer rather than the high intensity mixers taught by the prior art.
  • oxygen is introduced into the pulp within the connecting conduit upstream of a single in-line mixer.
  • a conduit downstream of the in-line mixer a conduit is positioned for introducing an alkaline solution to the mixture and downstream from that is a second in-line mixer for mixing the alkaline solution with the pulp and oxygen.
  • Steam may be introduced through a conduit downstream of the alkaline mixer and a third in-line mixer may be utilized to mix the steam with the alkaline liquor, oxygen, and pulp mixture.
  • a single supply conduit is joined to the connecting conduit through which a combination of oxygen, alkaline chemicals, and steam is introduced upstream of a single in-line mixer.
  • some or all of the oxygen can be predispersed in the alkaline liquor prior to the introduction of the alkaline liquor into the pulp.
  • the oxygen may be predispersed in a liquid prior to the introduction of the oxygen into the pulp upstream of the mixing elements.
  • the liquid may be water, oxygen bleaching filtrate, or an alkaline solution.
  • the thick stock pump be located below the level of the reactor tube and that the connecting conduit be inclined upwardly from the pump to the reactor tube.
  • the connecting conduit can be joined to the tube either at the underside of the tube or through the top of the tube. This difference in elevation is necessary to prevent the reverse flow of oxygen gas through the connecting conduit to the thick stock pump where it could collect and present a hazard.
  • the oxygen is mixed with the pulp at a location in which the pressure is substantially greater than the operating pressure within the horizontal reactor tube because of the hydrostatic head and the friction losses within the connecting conduit leading to the reactor tube. Since the pressure is greater, the solubility of the oxygen is higher and the oxygen delignification reaction which is initiated at the location adjacent the pump occurs at an increased rate.
  • pulp at from 8-20% consistency and preferably 10-15% is contained within a pulp source 10 which communicates with a thick stock pump 12.
  • Pump 12 may be a Moyno progressing cavity pump available from Robbins & Myers, Inc., Springfield, Ohio.
  • pump 12 may be a Cloverotor thick stock pump manufactured by the Ingersoll Rand Company in Nashua, New Hampshire, a thick stock pump manufactured by Warren Pumps, Inc., Warren, Massachusetts, or any other type of thick stock or high density pump known in the industry.
  • a connecting conduit 14 extends from the pump 12 to an inlet 16 of a first or primary reactor tube 18.
  • the primary reactor tube 18 includes an outlet 20 communicating with a substantially vertical conduit 22 which communicates with the inlet 24 of a second reactor tube 26.
  • the second reactor tube 26 may be joined to subsequent reactor tubes 28,30, if desired, which ultimately are joined to a blow chamber 32.
  • the primary reactor tube 18 and the subsequent reactor tubes 26,28,30 each include a screw 34 with drive means 36, preferably an electric motor.
  • the screw 34 preferably has a helical flight design.
  • Each reactor tube 18,26,28,30 also includes an alkaline liquor supply line 38, which is optional, and a steam supply line 40.
  • the total alkaline material charge will be from 1-20% by weight calculated as Na 2 0 of the oven dry weight of the raw fibrous material.
  • alkaline materials suitable for use with this invention include sodium hydroxide, sodium carbonate, sodium borate compounds, ammonia, kraft white liquor, oxidized kraft white liquor and mixtures thereof, although other known alkaline pulping liquors may also be used.
  • the steam introduced through the steam supply lines preferably is sufficient to maintain the temperature within the reactor tubes 18,26,28,30 within the preferred temperature range of 80°-160°C.
  • the oxygen delignification system described to this point is of known design and is disclosed and discussed in greater detail in European application Serial No. 80304340.5, filed December 2, 1980.
  • the improvement in the system consists of adding an oxygen supply line 42 communicating with a source of oxygen under pressure and further communicating with the connecting conduit 14 at a location adjacent the thick stock pump 12. Downstream of the thick stock pump is located a means for mixing the oxygen with the stock which preferably is an in-line, motionless mixer 44.
  • An example of such a motionless mixer is a Komax triple action motionless mixer manufactured by Komax Systems, Inc., Long Beach, California.
  • the oxygen supplied through the line 42 may be in a gaseous form or predispersed in a liquid such as water, oxygen bleaching filtrate, or an alkaline solution, and is preferably supplied at a point adjacent the inlet of mixer 44.
  • the thick stock pump typically is of a type having a horizontal discharge. Since the pump 12 must be positioned at an elevation below that of the primary reactor tube 18, the connecting conduit 14 must include an upwardly inclined portion 46 in addition to a substantially horizontal portion 48. The difference in elevation is necessary to prevent oxygen gas, which is present above the stock within the primary reactor tube 18, from travelling backwardly from the reactor tube toward the thick stock pump 12.
  • the in-line mixer 44 although shown mounted along the horizontal portion 48 of the connecting conduit 14, alternatively may be positioned along the inclined portion 46 of the connecting conduit.
  • the operation of the oxygen delignification system shown in Fig. 1 is as follows. Pulp from the pulp source 10 is pumped by the thick stock pump 12 through the connecting conduit 14 to the primary reactor tube 18. Oxygen is introduced into the connecting conduit 14 through the supply line 42 at a point downstream of thick stock pump 12 and immediately upstream of the inlet to mixer 44. The oxygen and the stock are mixed as the stock flows through the in-line motionless mixer 44 at which time the oxygen delignification process is initiated. Consequently, the stock delivered to the primary reactor tube 18 through the inlet 16 contains dissolved oxygen and oxygen gas intimately dispersed within the stock slurry and is not delivered in a somewhat compacted mass devoid of oxygen. Accordingly, the length of primary reactor tube 18 can be shorter than that required for a system not having oxygen mixing occurring in the connecting conduit.
  • alkaline liquor is introduced to the pulp through supply line 38 and steam is introduced to the pulp through supply line 40.
  • some or all of the stream or alkaline chemicals may be added to the pulp prior to the thick stock pump.
  • additional oxygen may be introduced into the primary reactor tube 18 through a supply line 50.
  • the pulp As the pulp travels along the length of the primary reactor tube 18 driven by screw 34, it further reacts with the oxygen present in the tube and the alkaline solution. Temperature is maintained by the steam so that the delignification process continues at an adequate rate.
  • the pulp exits the primary reactor tube 18 through the outlet 20 and falls through the vertical conduit 22 to the second reactor tube through the inlet 24.
  • the delignification process continues in the same manner until the delignified pulp is deposited into the blow region 32. In some instances, only a single reaction tube is required to achieve the desired degree of delignification.
  • FIG. 2 A second embodiment of the invention is shown in Fig. 2 in which the primary reactor tube 18 receives ,stock from the pump (not shown) through a connecting conduit 14'.
  • Connecting conduit 14' communicates with a source of oxygen through an oxygen supply line 42'.
  • the conduit 14' communicates with a source of alkaline liquor through an alkaline supply line 52, and communicates with a source of steam through a steam supply line 54.
  • Downstream of each of the supply lines 42',52,54, are positioned in-line, motionless mixer elements 44A,44B,44C. These elements may be three separate mixers or may comprise elements in a single mixer.
  • an alternate inlet 16' may be provided for the reactor tube 18 which permits the stock to be pumped into the reactor tube from the underside.
  • the oxygen supply line 42' preferably is upstream of the alkaline liquor supply line 52 and the steam supply line 54. Should the alkaline liquor or the steam be added prior to the addition of the oxygen, loss in pulp yield or loss in pulp strength or viscosity may result. Furthermore, it is preferable to maintain the location at which the oxygen line 42' is positioned adjacent the thick stock pump (not shown) and immediately upstream of the inlet of mixer element 44A so that the oxygen enters the stock at a point where a relatively high pressure exists. It is desirable to add alkaline liquor and steam to the connecting conduit 14' to increase the pH and temperature to optimum levels which improves the rate of oxygen delignification within the connecting conduit.
  • the conduit 14' conveys pulp from the thick stock pump and the pulp receives oxygen from line 42', which is mixed with the pulp in mixer 44A to initiate the delignification reaction.
  • the pH level and temperature of the mixture is maintained by injections of alkaline chemicals and steam into the stock from lines 52,54. After each injection, the mixture is mixed by mixers 44B,44C to maintain the homogeneity of the mixture.
  • the pulp mass entering reactor 18 is more readily accessible to the oxygen gas in the reactor than it would be without the improvement of the present invention.
  • FIG. 2 A modification of the second embodiment of the invention is also illustrated in Fig. 2 in which some or all of the oxygen may be supplied via line 60 to alkaline solution 52.
  • the oxygen is dispersed into the alkaline solution using a venturi-type system, injector, diffuser, or small motionless mixer, as well as other known methods.
  • a third embodiment of the invention is shown in Fig. 3 and is similar to the preceding embodiments except-that a connecting conduit 14" suppling the primary reactor tube (not shown) with stock from the pump (not shown) includes a single supply line 56 which communicates with sources of oxygen, alkaline liquor, and steam.
  • the supply line 56 preferably terminates in a distribution ring 58, or other suitable gas dispersion apparatus, having nozzles arranged about its inner periphery to distribute the oxygen, alkaline liquor, and steam evenly about the stock.
  • the supply line 56 and distribution ring 58 preferably are located adjacent the thick stock pump and upstream of an in-line, motionless mixer 44.
  • stock flowing from the pump receives a mixed stream of oxygen, steam, and alkaline solution through line 56 and ring 58.
  • the charge is immediately mixed with the stock by mixer 44 to initiate the delignification reaction throughout the pulp flowing downstream of the ring 58.
  • the pulp entering the reactor tube is already partially delignified and is at the optimum pH level and temperature.
  • a system such as that disclosed in Fig. 3 would provide the lowest cost form of the invention and would provide a hot gas-liquid mixture to be injected into the connecting conduit 14".
  • oxygen gas is used as the source of oxygen, the gas could be well dispersed in the alkaline liquid using a venturi-type system, injector, diffuser, or a small motionless mixer, as well as other known methods.
  • An additional advantage of the invention is that, when white liquor is used as the alkaline chemical, the sodium sulfide in the white liquor reacts with the oxygen and is somewhat oxidized before it is added to the pulp. In some cases, this can result in an improved pulp viscosity and strength.
EP83304894A 1982-09-30 1983-08-24 Verfahren und Vorrichtung zur Sauerstoffdelignifizierung Ceased EP0106460A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US43148682A 1982-09-30 1982-09-30
US431486 1982-09-30

Publications (1)

Publication Number Publication Date
EP0106460A1 true EP0106460A1 (de) 1984-04-25

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EP83304894A Ceased EP0106460A1 (de) 1982-09-30 1983-08-24 Verfahren und Vorrichtung zur Sauerstoffdelignifizierung

Country Status (9)

Country Link
EP (1) EP0106460A1 (de)
JP (1) JPS5982488A (de)
KR (1) KR840005846A (de)
BR (1) BR8305348A (de)
CA (1) CA1213104A (de)
ES (1) ES8504999A1 (de)
FI (1) FI833514A (de)
NO (1) NO833033L (de)
ZA (1) ZA835925B (de)

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0167060A1 (de) * 1984-06-20 1986-01-08 Union Carbide Corporation Verfahren zum Dispergieren eines Fluidums in ein anderes
EP0226495A1 (de) * 1985-11-15 1987-06-24 Canadian Liquid Air Ltd Air Liquide Canada Ltee Verfahren und Vorrichtung zum Bleichen von Papierpulpe
EP0295180A2 (de) * 1987-06-08 1988-12-14 Canadian Liquid Air Ltd Air Liquide Canada Ltee Verfahren zum Bleichen oder zur Delignifizierung eines Zellstoffs mit Sauerstoff, und Anlage zur Durchführung des Verfahrens
US5085734A (en) * 1989-02-15 1992-02-04 Union Camp Patent Holding, Inc. Methods of high consistency oxygen delignification using a low consistency alkali pretreatment
US5164044A (en) * 1990-05-17 1992-11-17 Union Camp Patent Holding, Inc. Environmentally improved process for bleaching lignocellulosic materials with ozone
US5164043A (en) * 1990-05-17 1992-11-17 Union Camp Patent Holding, Inc. Environmentally improved process for bleaching lignocellulosic materials with ozone
US5173153A (en) * 1991-01-03 1992-12-22 Union Camp Patent Holding, Inc. Process for enhanced oxygen delignification using high consistency and a split alkali addition
US5174861A (en) * 1990-10-26 1992-12-29 Union Camp Patent Holdings, Inc. Method of bleaching high consistency pulp with ozone
US5181989A (en) * 1990-10-26 1993-01-26 Union Camp Patent Holdings, Inc. Reactor for bleaching high consistency pulp with ozone
US5188708A (en) * 1989-02-15 1993-02-23 Union Camp Patent Holding, Inc. Process for high consistency oxygen delignification followed by ozone relignification
WO1993009391A1 (en) * 1991-11-06 1993-05-13 Sunds Defibrator Industries Aktiebolag Heating arrangement
US5211811A (en) * 1989-02-15 1993-05-18 Union Camp Patent Holding, Inc. Process for high consistency oxygen delignification of alkaline treated pulp followed by ozone delignification
US5217574A (en) * 1989-02-15 1993-06-08 Union Camp Patent Holdings Inc. Process for oxygen delignifying high consistency pulp by removing and recycling pressate from alkaline pulp
US5409570A (en) * 1989-02-15 1995-04-25 Union Camp Patent Holding, Inc. Process for ozone bleaching of oxygen delignified pulp while conveying the pulp through a reaction zone
US5451296A (en) * 1991-05-24 1995-09-19 Union Camp Patent Holding, Inc. Two stage pulp bleaching reactor
US5472572A (en) * 1990-10-26 1995-12-05 Union Camp Patent Holding, Inc. Reactor for bleaching high consistency pulp with ozone
US5520783A (en) * 1990-10-26 1996-05-28 Union Camp Patent Holding, Inc. Apparatus for bleaching high consistency pulp with ozone
US5525195A (en) * 1989-02-15 1996-06-11 Union Camp Patent Holding, Inc. Process for high consistency delignification using a low consistency alkali pretreatment
WO2009097877A1 (de) * 2008-02-08 2009-08-13 Voith Patent Gmbh Misch- und verdünnungsanordnung und verfahren
WO2009097878A1 (de) * 2008-02-08 2009-08-13 Voith Patent Gmbh Mischanordnung und verfahren

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61137696U (de) * 1985-02-13 1986-08-27

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2000953A (en) * 1933-10-30 1935-05-14 Hooker Electrochemical Co Means for reacting semifluid materials
US4161421A (en) * 1977-09-13 1979-07-17 Kamyr, Inc. Method and apparatus for continuous oxygen bleaching of cellulosic pulp

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2000953A (en) * 1933-10-30 1935-05-14 Hooker Electrochemical Co Means for reacting semifluid materials
US4161421A (en) * 1977-09-13 1979-07-17 Kamyr, Inc. Method and apparatus for continuous oxygen bleaching of cellulosic pulp

Cited By (27)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0167060A1 (de) * 1984-06-20 1986-01-08 Union Carbide Corporation Verfahren zum Dispergieren eines Fluidums in ein anderes
EP0226495A1 (de) * 1985-11-15 1987-06-24 Canadian Liquid Air Ltd Air Liquide Canada Ltee Verfahren und Vorrichtung zum Bleichen von Papierpulpe
EP0295180A2 (de) * 1987-06-08 1988-12-14 Canadian Liquid Air Ltd Air Liquide Canada Ltee Verfahren zum Bleichen oder zur Delignifizierung eines Zellstoffs mit Sauerstoff, und Anlage zur Durchführung des Verfahrens
FR2617877A1 (fr) * 1987-06-08 1989-01-13 Liquid Air Canada Procede de blanchiment ou de delignification d'une pate cellulosique par l'oxygene, et installation pour sa mise en oeuvre
EP0295180A3 (de) * 1987-06-08 1989-10-11 Canadian Liquid Air Ltd Air Liquide Canada Ltee Verfahren zum Bleichen oder zur Delignifizierung eines Zellstoffs mit Sauerstoff, und Anlage zur Durchführung des Verfahrens
AU613952B2 (en) * 1987-06-08 1991-08-15 Canadian Liquid Air Ltd. Method of bleaching or delignification of cellulose pulp with oxygen
US5188708A (en) * 1989-02-15 1993-02-23 Union Camp Patent Holding, Inc. Process for high consistency oxygen delignification followed by ozone relignification
US5211811A (en) * 1989-02-15 1993-05-18 Union Camp Patent Holding, Inc. Process for high consistency oxygen delignification of alkaline treated pulp followed by ozone delignification
US5525195A (en) * 1989-02-15 1996-06-11 Union Camp Patent Holding, Inc. Process for high consistency delignification using a low consistency alkali pretreatment
US5409570A (en) * 1989-02-15 1995-04-25 Union Camp Patent Holding, Inc. Process for ozone bleaching of oxygen delignified pulp while conveying the pulp through a reaction zone
US5085734A (en) * 1989-02-15 1992-02-04 Union Camp Patent Holding, Inc. Methods of high consistency oxygen delignification using a low consistency alkali pretreatment
US5217574A (en) * 1989-02-15 1993-06-08 Union Camp Patent Holdings Inc. Process for oxygen delignifying high consistency pulp by removing and recycling pressate from alkaline pulp
US5164043A (en) * 1990-05-17 1992-11-17 Union Camp Patent Holding, Inc. Environmentally improved process for bleaching lignocellulosic materials with ozone
US5164044A (en) * 1990-05-17 1992-11-17 Union Camp Patent Holding, Inc. Environmentally improved process for bleaching lignocellulosic materials with ozone
US5863389A (en) * 1990-10-26 1999-01-26 Union Camp Patent Holding, Inc. Pulp bleaching reactor for dispersing high consistency pulp into a gaseous bleaching agent containing ozone
US5181989A (en) * 1990-10-26 1993-01-26 Union Camp Patent Holdings, Inc. Reactor for bleaching high consistency pulp with ozone
US5472572A (en) * 1990-10-26 1995-12-05 Union Camp Patent Holding, Inc. Reactor for bleaching high consistency pulp with ozone
US5520783A (en) * 1990-10-26 1996-05-28 Union Camp Patent Holding, Inc. Apparatus for bleaching high consistency pulp with ozone
US5174861A (en) * 1990-10-26 1992-12-29 Union Camp Patent Holdings, Inc. Method of bleaching high consistency pulp with ozone
US5173153A (en) * 1991-01-03 1992-12-22 Union Camp Patent Holding, Inc. Process for enhanced oxygen delignification using high consistency and a split alkali addition
US5451296A (en) * 1991-05-24 1995-09-19 Union Camp Patent Holding, Inc. Two stage pulp bleaching reactor
US5989388A (en) * 1991-05-24 1999-11-23 Union Camp Patent Holding, Inc. Method for ozone bleaching of high consistency pulp in two stages
WO1993009391A1 (en) * 1991-11-06 1993-05-13 Sunds Defibrator Industries Aktiebolag Heating arrangement
US5479792A (en) * 1991-11-06 1996-01-02 Sunds Defibrator Industries Aktiebolag Heating arrangement
WO2009097877A1 (de) * 2008-02-08 2009-08-13 Voith Patent Gmbh Misch- und verdünnungsanordnung und verfahren
WO2009097878A1 (de) * 2008-02-08 2009-08-13 Voith Patent Gmbh Mischanordnung und verfahren
CN101939086A (zh) * 2008-02-08 2011-01-05 沃依特专利有限责任公司 混合装置和方法

Also Published As

Publication number Publication date
ZA835925B (en) 1984-04-25
FI833514A0 (fi) 1983-09-29
BR8305348A (pt) 1984-05-08
FI833514A (fi) 1984-03-31
NO833033L (no) 1984-04-02
JPS5982488A (ja) 1984-05-12
ES526161A0 (es) 1985-05-01
ES8504999A1 (es) 1985-05-01
KR840005846A (ko) 1984-11-19
CA1213104A (en) 1986-10-28

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