US3532594A - Method of digesting cellulosic material in steam phase - Google Patents

Method of digesting cellulosic material in steam phase Download PDF

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Publication number
US3532594A
US3532594A US666737A US3532594DA US3532594A US 3532594 A US3532594 A US 3532594A US 666737 A US666737 A US 666737A US 3532594D A US3532594D A US 3532594DA US 3532594 A US3532594 A US 3532594A
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liquor
chips
steam
digester
digesting
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US666737A
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Johan C F C Richter
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Metso Fiber Karlstad AB
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Kamyr AB
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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
    • D21C1/00—Pretreatment of the finely-divided materials before digesting
    • D21C1/10—Physical methods for facilitating impregnation

Definitions

  • the present invention concerns a method of continuous digestion of cellulosic fiber material, such as wood chips.
  • the chips are first impregnated with digesting liquor in an impregnation vessel under a reduced pressure and then transferred to a digester, in the upper part of which the fiber-liberating digestion takes place in gas phase.
  • the chips are heated and the digester is held under a high pressure by means of high-pressure steam supplied to the top of digester. Only a part of the liquor quantity required for the digestion of the chips is absorbed by the chips while immersed in digesting liquor in the impregnation vessel.
  • the remainder of the liquor is supplied as a spray or mist of minute drops to the upper end of the digester where it will settle upon the surfaces of the chips particles together with the steam ,thus maintaining proper liquor strength in the surface layers and preventing leaching by the steam condensate.
  • the steam used for heating the digester also serves for atomizing the liquor supplied to the digester.
  • the lower part of digester is filled with liquid driven in counter-current flow to chips for washing out the black liquor thereof.
  • the present invention relates to the digestion in steam phase of finely comminuted fiber material, such as wood chips, which has been impregnated in advance with digesting liquor by immersion of the fiber material into digesting liquor in a separate impregnation vessel from which the fiber material is transferred, after draining of digesting liquor not absorbed, to the steam space of a digester in which fiber-liberating digestion is performed.
  • the chips absorb a sufficiently great quantity of the digesting chemicals, such as alkali, required for the digestion.
  • the chips have a high moisture content in their raw condition and that often the moisture content is further increased by their steaming, being a usual preparatory measure to the digestion.
  • the used digesting liquor usually is of a quite moderate strength, this applying particularly to the case when the liquor is taken from a recovery plant where the causticising reaction of the liquor limits its concentration. Therefore, it has been necessary to take measures for removing water from the chips or the liquor, such as drying of the chips, removal of steam by flashing in the impregnation vessel or preevaporation of the digesting liquor.
  • the invention has for its object to eliminate said difficulties, so that the measures just mentioned become wholly or partly superfluous. According to the main feature of the invention said object is reached thereby that a portion of the total liquor quantity required for the digesting reaction is supplied separately to the steam space of the digester as a spray of minute drops. Then it can be accepted that the impregnation of the chips with digesting liquor performed in the impregnation vessel is incomplete, i.e.
  • the liquor quantity absorbed by the chips and accompanying the same into the digester is insufiicient for the digestion, because by the addition of an extra quantity of liquor to the steam space of the digester said deficiency is compensated so that the quantity of liquor required for a complete dissolution of the lignin from the fiber material is present in the digester.
  • the liquor portion separately supplied to the digester is atomized and distributed in the digester preferably by means of such high-pressure steam as is supplied to the steam space of the digester for the purpose of heating the fiber material to digesting temperature.
  • 11 designates an upright cylindrical steaming and low-pressure impregnation vessel, to the upper end of which the finely comminuted fiber material, e.g. wood chips, that should be digested, is supplied via a rotary valve 13 with a pocketed rotor serving as a pressure lock. Steaming of the chips is performed in the upper part of said vessel by means of low-pressure steam supplied through the conduit 15 in a quantity controlled by the valve 17, which steam is spread from the lower end of a vertical tube 19 suspended in the vessel 11. Such air as is displaced by the steam is discharged through the conduit 12 connected to the top of the digester.
  • the finely comminuted fiber material e.g. wood chips
  • the steam condenses upon the chips and heats the same to approximately C.
  • the pressure in the vessel 11 may be of the order of 1 to 2 atmospheres overpressure.
  • the chips are impregnated with digesting liquor, such as sulphate liquor, which is supplied through the conduit 21 and is driven by the pump 23 through a heat exchanger 25 and into the vessel through the conduit 27 suspended therein.
  • digesting liquor such as sulphate liquor
  • diluting liquor preferably black liquor, which is more or less chemically inactive and which is taken from the conduit 29.
  • the quantity thereof is controlled by a valve 31 controlled by a level control device by means of which the surface of the liquid filling of the vessel can be maintained at a desired level 33, preferably being adjustable.
  • a conduit leading from a screen girdle 35 inserted in the shell of the vessel is also connected to the inlet side of the pump 23 , the pump thus maintaining a circulation of digesting liquor in a circuit through 35, 23, 25, 27.
  • Said circulating liquor as well as newly supplied white liquor from the conduit 21 and possibly black liquor from the conduit 29 are heated indirectly in the heat exchanger 25 by means of low-pressure steam taken from the conduit 15.
  • the valve 37 in the steam conduit controls the temperature of the circulating liquor, so that the same is maintained at a desired value, e.g., C. Due to said indirect heating of the digesting liquor the steam quantity required for direct heating and supplied through the conduit 19 is decreased. Thus it is possible to reduce and within certain limits to control the dilution of the digesting liquor with steam condensate. If desired, the steam supplied through the conduit 19 may be shut off and the indirect heating made so great that water in the vessel 11 is evaporated, the steam formed departing through the conduit 12.
  • a suspension of the steamed and impregnated fiber material in digesting liquor is discharged at the bottom of the vessel 11 'by means of a rotary discharging device 39 preferably being of the kind shown in the U.S. Pat. No.
  • the motor driving said discharging device is controlled by a level control means 41, whereby the discharge takes place at such a rate that the level of the chips at the upper end of the vessel is maintained constant.
  • the mixture of chips and digesting liquor is pumped to the top of a digester 43 by means of a circulation system held under the digesting pressure and which includes a high-pressure valve 45 and a screening device 47 in open communication with the digester top.
  • the valve 54 comprises a rotary plug having a pocket which, in the shown vertical position, is filled with chips with the aid of liquor circulated by means of the pump 49 in a closed loop on the low-pressure side of the valve.
  • Such liquor as penetrates the cylindrical screen 57 is returned through the conduit 53, whereas the chips retained by said screen are fed by means of a motor-driven conveyor screw 59 through the inclined housing of the screening device up to its uppermost end where the chips drop into the digester 43 due to the gravity.
  • a predetermined liquor level 61 is maintained in the screening device by means of a valve 63 controlled by impulses derived from said level, and a pump 65 which returns to the high-pressure circulation loop such liquid as, due to the operation of the valve 45, has been let out into low-pressure circulation loop.
  • the chips are digested in the gas phase after having been heated by highpressure steam supplied through the conduit 67 in such a quantity controlled by the valve 69 that a pressure of the order of 10 atmospheres and a corresponding temperature, e.g. approximately 170 C., are maintained in the digester.
  • the digested fiber material is washed by means of wash liquid supplied through the conduit 71 and pumped by means of the pump 73 into the lower end of the digester in such a quantity controlled by the valve 75 that the digester is maintained filled with liquid to the desired level 77.
  • the wash liquid is heated indirectly with steam in a loop comprising screen girdle 79, pump 81, heat exchanger 83 and the central tube 85.
  • the wash liquid thus heated is driven upwardly and in counter-current flow to the slowly descending chips column, displacing its content of spent liquor which departs through the screen girdle 87 and is carried off to the blow tank 89.
  • the pressure of the liquor is lowered, steam being released which may be supplied through the conduit 91 to the vessel 11 for the purpose of steaming the chips.
  • the quantity of steam supplied through the conduit 15 can be lowered in a corresponding degree or may possibly be wholly shut off by means of the valve 17.
  • a forced horizontal and radial flow of liquid is maintained at the level of the screen girdle 87 by means of the pump 93 and the central conduit 95, thereby improving the washing effect.
  • the departing total quantity of liquid and thus the quantity of wash liquid mixed into the spent liquor can be controlled by the adjustable valve 97.
  • the digested fiber material is discharged at the lower end of the digester by means of a rotary scraper 99 and a throttling device 101.
  • a valve 103 inserted in the pulp discharge conduit and a level sensing device 105 the discharge is controlled in such a manner that the digester is maintained filled with chips to the desired level.
  • the digesting liquor is divided up into two portions, the main portion of which being introduced in the above-described manner by means of the pump 23 into the impregnation vessel 11, whereas the remaining smaller portion is supplied by means of the pump 107 and the conduit 109 to the steam space of the digester.
  • Said latter liquor portion is preferably introduced into the high-pressure steam supplied to the upper end of the digester for the purpose of heating the chips to digesting temperature, the steam being utilized to atomize the liquor.
  • the liquor from the conduit 109 may be supplied to an ejector or spreader device 111 inserted in the steam conduit 67, so that the liquor is introduced into the digester in the shape of minute drops together with the steam.
  • the total quantity of the supplied white liquor is controlled by a valve 117 in the conduit 21, which is adjusted so as to admit white liquor in a quantity which corresponds to the quantity of chips fed into the vessel 11 by the valve 13 and which is suitable for a proper digestion of the fiber material in the digester.
  • the difference between the white liquor quantities admitted by the valves 117 and 113 goes to the impregnation vessel 11 wherein it is absorbed by the chips.
  • the course of absorption in the impregnation vessel may be modified in various manners in order to bring about that the chips carry with them exactly the white liquor portion remaining when the quantity supplied directly to the digester has been deducted from the totally required white liquor quantity.
  • the duration of impregnation may be varied by raising or lowering the liquor level 33.
  • the digesting liquor in the impregnation vessel may be diluted, e.g. by replacing at least part of the black liquor supplied through conduit 29, by water.
  • the addition of liquor to the steam used for heating the chips in the digester also has the favorable eifect that the condensate formed by said steam and deposited upon the surfaces of the chips, will not dilute the liquor whereby the surface layers of the chips have been impregnated in the vessel 11, but the liquor deposited upon the surfaces of the chips together with the steam serves to maintain approximately the same liquor strength therein as in the interior of the chips, thus favoring an even digestion of the fiber material.
  • the method of fiber-liberating digestion of comminuted fibrous material which comprises the steps of impregnating said fibrous material by immersing it in digesting liquor in an impregnation vessel, wherein said fibrous material absorbs a portion of the digesting liquor, draining from the impregnated fibrous material the digesting liquor not therein absorbed, transferring the drained fibrous material to the steam space of a digester, and supplying to said steam space of the digester steam and as an atomized spray or mist of minute drops, the remaining portion of the digesting liquor required to maintain sufficient liquor strength in the surface layers of said comminuted fibrous material to complete dissolution of lignin therefrom and to prevent leaching of the digesting liquor by the steam condensate.
  • Method according to claim 1 which further includes the steps of supplying said remaining portion of the digesting liquor to the steam space by injection with high pressure steam and atomizing said remaining portion of the digesting liquor by means of high-pressure steam supplied to the steam space of the digester for heating the fiber material to digesting temperature.
  • Method according to claim 1 which further includes the steps of supplying said remaining portion of the digesting liquor to the steam space by injection with high pressure steam, and distributing said remaining portion of the atomized digesting liquor upon the fiber material particles during their transfer by gravity drop into the digester.
  • Method according to claim 1 which further includes the step of controlling the time of impregnation by varying the liquor level in the impregnation vessel.
  • Method according to claim 1 which further includes the step of controlling the evaporation of the liquid content of the digesting liquor in the impregnation vessel.

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US666737A 1966-09-12 1967-09-11 Method of digesting cellulosic material in steam phase Expired - Lifetime US3532594A (en)

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SE12221/66A SE330819B (enrdf_load_stackoverflow) 1966-09-12 1966-09-12

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Cited By (34)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4057461A (en) * 1975-06-02 1977-11-08 Kamyr Aktiebolag Method and apparatus for impregnation of fiber material by pressure pulsation
US4096027A (en) * 1976-02-19 1978-06-20 Kamyr Inc. System for presteaming wood chips at or near atmospheric pressure with minimum displacement of air
US4155805A (en) * 1978-01-19 1979-05-22 Kamyr Aktiebolag Method for continuously digesting cellulosic fiber by evenly spreading the fiber material over the digestion vessel with steam
US4190490A (en) * 1974-04-03 1980-02-26 Domtar Inc. Impregnation and digestion of wood chips
US5080755A (en) * 1988-12-20 1992-01-14 Kamyr Ab Process for the continuous digestion of cellulosic fiber material
US5192396A (en) * 1988-12-20 1993-03-09 Kamyr Ab Process for the continuous digestion of cellulosic fiber material
US5424417A (en) * 1993-09-24 1995-06-13 Midwest Research Institute Prehydrolysis of lignocellulose
EP0746650A4 (en) * 1992-01-29 1998-01-07 Alcell Tech Inc REDUCTION OF FIBROUS PLANT MATERIALS AND RECOVERY OF RESULTING BY-PRODUCTS
US5766418A (en) * 1996-09-13 1998-06-16 Ahlstrom Machinery Inc. Handling fibrous material used to produce cellulose pulp
US5788812A (en) * 1985-11-05 1998-08-04 Agar; Richard C. Method of recovering furfural from organic pulping liquor
WO1998035092A1 (en) * 1997-02-10 1998-08-13 Kvaerner Pulping Ab Method and device for the continuous cooking of chemical pulp
US5795438A (en) * 1996-11-04 1998-08-18 Ahlstrom Machinery Inc. Method and apparatus for feeding multiple digesters
US5876505A (en) * 1998-01-13 1999-03-02 Thermo Fibergen, Inc. Method of producing glucose from papermaking sludge using concentrated or dilute acid hydrolysis
US5882477A (en) * 1997-02-10 1999-03-16 Ahlstrom Machinery, Inc. Continuous digester with a low temperature gas-phase
US5985096A (en) * 1997-09-23 1999-11-16 Ahlstrom Machinery Inc. Vertical pulping digester having substantially constant diameter
US6123808A (en) * 1997-12-09 2000-09-26 Ahlstrom Machinery Inc. Distribution of dilution liquor to the discharge of a cellulose pulp digester
US6361649B1 (en) * 1997-02-10 2002-03-26 Kvaerner Pulping Ab Method for the continuous cooking of chemical pulp
US20020129911A1 (en) * 2000-10-16 2002-09-19 Marcoccia Bruno S. Process and configuration for providing external upflow/internal downflow in a continuous digester
US20030145963A1 (en) * 2002-02-04 2003-08-07 Stromberg C. Bertil Gas phase continuous digester having an inverted top separator with liquor injection
WO2006001758A1 (en) * 2004-06-23 2006-01-05 Kvaerner Pulping Ab Method and arrangement for impregnation of chips
WO2006006934A1 (en) * 2004-07-15 2006-01-19 Kvaerner Pulping Ab Method and arrangement for impregnating chips
US20060070709A1 (en) * 2002-05-21 2006-04-06 Vidar Snekkenes Method for the continuous cooking of wood raw material for cellulose pulp
US20100051222A1 (en) * 2008-08-27 2010-03-04 Andre Turqueti Continuous digester system
CN101235605B (zh) * 2008-02-28 2010-07-21 中国石油化工股份有限公司 一种包含酸回收的木质纤维素预处理的方法及其系统
WO2011021968A1 (en) 2009-08-19 2011-02-24 Metso Fiber Karlstad Ab Method and arrangement for adding treatment liquors to cellulose raw material in a continuous process using down flow vessels
US20110056642A1 (en) * 2008-03-20 2011-03-10 Anders Samuelsson Feeding system comprising pumps in parallel for a continuous digester
US20110067833A1 (en) * 2008-03-20 2011-03-24 Anders Samuelsson Feeding system comprising parallel pumps and individual flows for a digester
US20110073266A1 (en) * 2008-03-20 2011-03-31 Anders Samuelsson Feeding system comprising pumps in parallel for a continuous digester
US20110083822A1 (en) * 2008-03-20 2011-04-14 Anders Samuelsson Feeding system comprising parallel pumps for a continuous digester
US20110108223A1 (en) * 2008-03-24 2011-05-12 Theodora Retsina Method For Vapor Phase Pulping With Alcohol and Sulfur Dioxide
US20110259539A1 (en) * 2008-03-20 2011-10-27 Anders Samuelsson Feeding system comprising parallel pumps for a continuous digester
US20140246158A1 (en) * 2007-05-23 2014-09-04 Andritz Inc. Two vessel reactor system and method for hydrolysis and digestion of wood chips with chemical enhanced wash method
US9644317B2 (en) 2014-11-26 2017-05-09 International Paper Company Continuous digester and feeding system
US10648008B2 (en) 2008-12-17 2020-05-12 Borregaard Industries, Limited, Norge Lignocellulosic biomass conversion

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2492047A (en) * 1946-03-30 1949-12-20 Du Pont Bleaching wood pulp
US2858213A (en) * 1956-04-20 1958-10-28 Condi Engineering Corp Wood chip digestion
US3258390A (en) * 1962-10-20 1966-06-28 Domtar Ltd Method and apparatus for maintaining a water balance during impregnation and digestion of cellulosic material

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2492047A (en) * 1946-03-30 1949-12-20 Du Pont Bleaching wood pulp
US2858213A (en) * 1956-04-20 1958-10-28 Condi Engineering Corp Wood chip digestion
US3258390A (en) * 1962-10-20 1966-06-28 Domtar Ltd Method and apparatus for maintaining a water balance during impregnation and digestion of cellulosic material

Cited By (52)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4190490A (en) * 1974-04-03 1980-02-26 Domtar Inc. Impregnation and digestion of wood chips
US4057461A (en) * 1975-06-02 1977-11-08 Kamyr Aktiebolag Method and apparatus for impregnation of fiber material by pressure pulsation
US4096027A (en) * 1976-02-19 1978-06-20 Kamyr Inc. System for presteaming wood chips at or near atmospheric pressure with minimum displacement of air
US4155805A (en) * 1978-01-19 1979-05-22 Kamyr Aktiebolag Method for continuously digesting cellulosic fiber by evenly spreading the fiber material over the digestion vessel with steam
US5788812A (en) * 1985-11-05 1998-08-04 Agar; Richard C. Method of recovering furfural from organic pulping liquor
US5192396A (en) * 1988-12-20 1993-03-09 Kamyr Ab Process for the continuous digestion of cellulosic fiber material
US5080755A (en) * 1988-12-20 1992-01-14 Kamyr Ab Process for the continuous digestion of cellulosic fiber material
EP0746650A4 (en) * 1992-01-29 1998-01-07 Alcell Tech Inc REDUCTION OF FIBROUS PLANT MATERIALS AND RECOVERY OF RESULTING BY-PRODUCTS
US5424417A (en) * 1993-09-24 1995-06-13 Midwest Research Institute Prehydrolysis of lignocellulose
US5766418A (en) * 1996-09-13 1998-06-16 Ahlstrom Machinery Inc. Handling fibrous material used to produce cellulose pulp
US5795438A (en) * 1996-11-04 1998-08-18 Ahlstrom Machinery Inc. Method and apparatus for feeding multiple digesters
US6024837A (en) * 1997-02-10 2000-02-15 Ahlstrom Machinery Inc. Low temperature gas phase continuous digester
WO1998035092A1 (en) * 1997-02-10 1998-08-13 Kvaerner Pulping Ab Method and device for the continuous cooking of chemical pulp
US5882477A (en) * 1997-02-10 1999-03-16 Ahlstrom Machinery, Inc. Continuous digester with a low temperature gas-phase
US6361649B1 (en) * 1997-02-10 2002-03-26 Kvaerner Pulping Ab Method for the continuous cooking of chemical pulp
US5985096A (en) * 1997-09-23 1999-11-16 Ahlstrom Machinery Inc. Vertical pulping digester having substantially constant diameter
US6123808A (en) * 1997-12-09 2000-09-26 Ahlstrom Machinery Inc. Distribution of dilution liquor to the discharge of a cellulose pulp digester
US5876505A (en) * 1998-01-13 1999-03-02 Thermo Fibergen, Inc. Method of producing glucose from papermaking sludge using concentrated or dilute acid hydrolysis
US20020129911A1 (en) * 2000-10-16 2002-09-19 Marcoccia Bruno S. Process and configuration for providing external upflow/internal downflow in a continuous digester
US20030145963A1 (en) * 2002-02-04 2003-08-07 Stromberg C. Bertil Gas phase continuous digester having an inverted top separator with liquor injection
US7105076B2 (en) 2002-02-04 2006-09-12 Andritz Inc. Gas phase continuous digester having an inverted top separator with liquor injection
US20070000626A1 (en) * 2002-02-04 2007-01-04 Andritz, Inc. Gas phase continuous digester having an inverted top separator with liquor injection
US7455749B2 (en) 2002-02-04 2008-11-25 Andritz Inc. Gas phase continuous digester having an inverted top separator with liquor injection
US20060070709A1 (en) * 2002-05-21 2006-04-06 Vidar Snekkenes Method for the continuous cooking of wood raw material for cellulose pulp
US7279070B2 (en) * 2002-05-21 2007-10-09 Metso Fiber Karlstad Ab Method for the continuous cooking of wood raw material for cellulose pulp
US20080277081A1 (en) * 2004-06-23 2008-11-13 Lennart Gustavsson Method and Arrangement For Impregnation of Chips
WO2006001758A1 (en) * 2004-06-23 2006-01-05 Kvaerner Pulping Ab Method and arrangement for impregnation of chips
US7998310B2 (en) 2004-06-23 2011-08-16 Metso Paper Sweden Ab Method for impregnating chips
JP2008506862A (ja) * 2004-07-15 2008-03-06 メッツオ ファイバー カルルスタード アクチボラグ チップを含浸する方法及び装置
WO2006006934A1 (en) * 2004-07-15 2006-01-19 Kvaerner Pulping Ab Method and arrangement for impregnating chips
US20080093041A1 (en) * 2004-07-15 2008-04-24 Vidar Snekkenes Method and Arrangement for Impregnating Chips
US7901541B2 (en) 2004-07-15 2011-03-08 Metso Fiber Karlstad Ab Method and arrangement for impregnating chips
US9194080B2 (en) * 2007-05-23 2015-11-24 Andritz Inc. Two vessel reactor system and method for hydrolysis and digestion of wood chips with chemical enhanced wash method
US20140246158A1 (en) * 2007-05-23 2014-09-04 Andritz Inc. Two vessel reactor system and method for hydrolysis and digestion of wood chips with chemical enhanced wash method
CN101235605B (zh) * 2008-02-28 2010-07-21 中国石油化工股份有限公司 一种包含酸回收的木质纤维素预处理的方法及其系统
US8702909B2 (en) * 2008-03-20 2014-04-22 Valmet Aktiebolag Feeding system having pumps in parallel and individual flows for a digester
US8728278B2 (en) * 2008-03-20 2014-05-20 Valmet Ab Feeding system having pumps in parallel for a continuous digester
US20110073266A1 (en) * 2008-03-20 2011-03-31 Anders Samuelsson Feeding system comprising pumps in parallel for a continuous digester
US20110083822A1 (en) * 2008-03-20 2011-04-14 Anders Samuelsson Feeding system comprising parallel pumps for a continuous digester
US20110056642A1 (en) * 2008-03-20 2011-03-10 Anders Samuelsson Feeding system comprising pumps in parallel for a continuous digester
US20110259539A1 (en) * 2008-03-20 2011-10-27 Anders Samuelsson Feeding system comprising parallel pumps for a continuous digester
US8574402B2 (en) * 2008-03-20 2013-11-05 Metso Paper Sweden Ab Feeding system having pumps in parallel for a continuous digester
US20110067833A1 (en) * 2008-03-20 2011-03-24 Anders Samuelsson Feeding system comprising parallel pumps and individual flows for a digester
US8709211B2 (en) * 2008-03-20 2014-04-29 Valmet Aktiebolag Feeding system having pumps in parallel for a continuous digester
US8709212B2 (en) * 2008-03-20 2014-04-29 Valmet Aktiebolag Feeding system having parallel pumps for a continuous digester
US20110108223A1 (en) * 2008-03-24 2011-05-12 Theodora Retsina Method For Vapor Phase Pulping With Alcohol and Sulfur Dioxide
US8038842B2 (en) 2008-03-24 2011-10-18 American Process, Inc. Method for vapor phase pulping with alcohol, sulfur dioxide and ammonia
US7867363B2 (en) 2008-08-27 2011-01-11 Metso Fiber Karlstad Ab Continuous digester system
US20100051222A1 (en) * 2008-08-27 2010-03-04 Andre Turqueti Continuous digester system
US10648008B2 (en) 2008-12-17 2020-05-12 Borregaard Industries, Limited, Norge Lignocellulosic biomass conversion
WO2011021968A1 (en) 2009-08-19 2011-02-24 Metso Fiber Karlstad Ab Method and arrangement for adding treatment liquors to cellulose raw material in a continuous process using down flow vessels
US9644317B2 (en) 2014-11-26 2017-05-09 International Paper Company Continuous digester and feeding system

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Publication number Publication date
SE330819B (enrdf_load_stackoverflow) 1970-11-30
NO118407B (enrdf_load_stackoverflow) 1969-12-22

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