US2474862A - Process and apparatus for continuous digestion of fibrous materials - Google Patents

Process and apparatus for continuous digestion of fibrous materials Download PDF

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Publication number
US2474862A
US2474862A US512978A US51297843A US2474862A US 2474862 A US2474862 A US 2474862A US 512978 A US512978 A US 512978A US 51297843 A US51297843 A US 51297843A US 2474862 A US2474862 A US 2474862A
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Prior art keywords
digester
liquor
temperature
pressure
digestion
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Expired - Lifetime
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US512978A
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English (en)
Inventor
Richter John Christoffer Carl
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Metso Fiber Karlstad AB
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Kamyr AB
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Application filed by Kamyr AB filed Critical Kamyr AB
Priority to US607694A priority Critical patent/US2459180A/en
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Publication of US2474862A publication Critical patent/US2474862A/en
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Expired - Lifetime legal-status Critical Current

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    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
    • D21C3/00—Pulping cellulose-containing materials
    • D21C3/22—Other features of pulping processes
    • D21C3/24—Continuous processes
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
    • D21C3/00—Pulping cellulose-containing materials
    • D21C3/22—Other features of pulping processes

Definitions

  • Digestion of wood or similar fibrous materials to cellulose, or for converting wood into sugar is effected at an increased pressure and at an elevated temperature, 130 to 180 C. or higher, according as the digestion is carried out according to the bisulphite process, the sulphate process, the sulphurous acid process, or some other process.
  • processes of digestion of this kind are exclusively carried out periodically, that is to say, the digestion is effected batch-wise, a digester being filled with the raw material, such as wood chips, after which the filling opening is closed and the digester liquor is admitted, and the temperature and pressure are then run up" in accordance with curves gained from experience, the pressure being determined by the pressure of the steam plus the partial pressure of the gases developed.
  • the cock is usually "gassed oil,” either in order to keep the pressure down, by discharge of air and $02, or in order to recover certain by-products, such as turpentine.
  • the abovementioned diiliculty can be avoided by feeding the wood chips into the bottom of the digester and discharging the digested pulp and the liquor over a discharge lip at the top of the digester, so that the digester always remains filled up to its top.
  • the digester should be vertical with its inlet at the top and the discharge at the bottom. In the first place, the material or mass which is specifically heavier, is most easily fed downwards. In the second place, the feeding apparatus when placed at the top of the digester, is more easily accessible for inspection and repair, than if it is placed at the bottom of the digester. In the third place, the digester is most easily emptied if the discharge is eilected from the bottom of the same.
  • the material should pass through zones having diflerent temperatures, substantially in such manner that the material first passes through a comparatively cold zone for the purpose of impregnation, and then through the digestion zone proper at full digestion temperature, and finally through a somewhat colder discharge zone.
  • the digester must be maintained under compression, that is to say, the liquor therein must be under a pressure which exceeds the steam pressure of the digester liquor at the maximum digestion temperature reached.
  • This pressure of the liquor may conveniently be identical to a pump pressure which is determined by the aid of a pressure regulator.
  • .4 comes automatically equal'to the difference between the quantity of the entire discharge and the sum of the quantities charged into the digester of raw material, liquor, including chemicals, and steam possibly introduced.
  • compression liquid itself, the only possibility that presents itself in practice is to use waste liquor, or so-called black liquor, in order not to lower the content of chemicals and dissolved substance in the liquor that is conducted to the liquor recovery. For economical reasons it is not possible to use water as compression liquid.
  • the process according to the present invention mainly consists in maintaining the material and the treating liquor during their movement through the digester at a pressure which is higher than the vapor pressure of the treating liquor at the maximum temperature prevailing in the digester, by pumping a compression liquid into the digester independently of the charging of raw material and treating liquor into said digester.
  • a compression liquid waste liquor or so-called black liquor may preferably be used. It is suitable to introduce the compression liquid at the discharge end of the digester, so that said liquid simultaneously serves to dilute and to effect discharge of the digested product.
  • Raw material is continuously supplied to the vertical digester 'I from the chip receptacle 2 which is provided with a vibration device 3 for producing a uniform supply of chips to a measuring apparatus 4, for instance in the form of a conveyer screw having a controllable speed, a blade wheel, a shaking apparatus, or some similar wellknown apparatus. Since the digester is assumed to be under a pressure which is higher than the vapor pressure of the digester liquor at the digestion temperature used, the digester must be completely filled with liquor.
  • the feeding of the raw material, such as wood chips, into this liquorfilled space under pressure is illustrated in the drawing as effected by means of a combination of a rotating cell wheel 5, a sieve 6 in a sieve housing provided at the top of the digester and surrounding a feeding screw I, a circulation pump 8, and conduits connecting the cell wheel, the sieve housing, and the pump.
  • the feeding is effected in the following manner: An empty cell in the cell wheel is partly filled with chips at ii and continues to rotate in the direction of the arrow, more liquor entering the cell at i2, for instance by leakage from It. At It the chips are emptied from the cell by the circulating liquor which is pumped by the pump 8 from the sieve 6 through the connection 8 to the cell in question, and is returned from said cell to the inner side of the sieve 6 wherethe chips brought along are fed downward into the digester by the screws '1, while the liquor is separated through the sieve and is returned in circulation to the cell wheel. The cell continues to rotate after the for gassing off air, for instance, in a well known manner.
  • the impregnation or digester liquor may be supplied, in a manner previously known in itself, either directly to the digester at 28, or at 28a through the receptacle l6 and the pump Ii.
  • Fresh liquor, S: or other chemicals may also be supplied wholly or partially at a later stage, for instance at 28b or at 28c, suitably in connection with a local circulation of the liquor and heating of the same by means of steam, as indicated at H.
  • the impregnation of the material takes place at a comparatively low temperature, 60 to 120 C., after which heatis supplied at I] either directly in the'form of steam or indirectly by local circulation of the liquor through a heat exchanger in a manner previously known in itself, for which reason such supply of heat has not been illustrated in the drawing.
  • the digestion temperature may for pressure actuated valve 21, so that the desired temperature of 120 C. is maintained at the bottom of the digester. If, on the other hand, the
  • instance be 140 to 180 C., or even higher.
  • the completely digested mass that is, the mixture of fibres and waste liquor
  • the discharge may be effected, for instance, by the aid of a scraper device 22 and a sluicing device 23 the capacity of which may be controlled by the aid of an automatic relay 2i.
  • a portion of the liquor separated at 20 is returned by means of the pump 25 and at a sumcient pressure for being introduced at 26 into the bottom of the digester to serve the purpose of diluting the stock or pulp in connection with the discharge of the same.
  • a valve 21 which is inserted in the pump conduit, and which is actuated by the pressure in the digester, the quantity of the compression liquid introduced at 26 is regulated in such manner that the desired compression is maintained in the digester, and consequently, during continuous operation the quantity of liquid pumped in at 26 becomes equal to the difference between the discharge quantity at 23 and the quantities of raw material, digester liquor, and steam introduced at I3, 28, 28b, 28c, l1 and Na, the discharge quantity at 23 being, of course, greater than the sum of the last mentioned quantities.
  • the discharge may be caused to take place at a desired predetermined temperature. For instance, if the relay 24 is adjusted for the temperature 120 0., then discharge will take place as long as, owing to the supply at 26 of compression liquid having a temperature of, say, 80 C., the temperature in the digester is decreased from, say, 170 C. to 120 C. at the discharge, and during all this time the supplied quantity of compression liquid is of for instance, to the temperature of the compression liquid increasing, then the relay 24 will increase the discharge rate at 23, and as a result hereof the relay 21 will also admit more compressionliquid at 26, so that the desired temperature of C. is maintained at the bottom of the digester.
  • the temperature relay 24 is adjusted for this temperature, and in such case a temperature of 30 C. will be maintained at the bottom of the digester.
  • the capacity of the sluicing device 23 shall of course be so large that said device is always capable of discharging not only the quantities of raw material, digester liquor, and steam introduced at I3, 28, 28b, 280, l1, and I la, but also the compression liquid introduced at", irrespective of the quantity thereof, and the temperature of this compression liquid must, of course, always be lower than the discharge temperature.
  • the entire course of digestion may thus be automatically controlled and regulated.
  • Apparatus for continuous digestion of iibrous materials comprising in combination a vertical digester, means for continuously introducing raw material into said digester at the top end thereof, means for continuously introducing digester liquor into said digester at the top end thereof, means for heating the fibrous material and digester liquor in said digester intermediate the top and bottom ends thereof, means for continuously discharging digested product from the bottom end 01' said digester, a conduit connected to said digester in the vicinity of the bottom end thereof for introducing a compression liquid in the digester at the bottom end, means in said conduit actuated by the pressure in said digester for controlling the flow of compression liquid through said conduit so as to maintain a predetermined pressure in said digester, a discharging apparatus having a variable capacity associated with the bottom end of digeeter ior continuously discharging digested product thereirom,
  • an adjustable temperature relay actuated by the temperature at the bottom end or the digester and operatively connected to said discharge apperatus so as to control the operation oi said apparatus in response to the temperature at the bottom end of the digester.

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US512978A 1942-10-15 1943-12-04 Process and apparatus for continuous digestion of fibrous materials Expired - Lifetime US2474862A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US607694A US2459180A (en) 1943-12-04 1945-07-30 Apparatus for charging fibrous material into a digester

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NO2474862X 1942-10-15

Publications (1)

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US2474862A true US2474862A (en) 1949-07-05

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US (1) US2474862A (de)
CH (1) CH243348A (de)
FR (1) FR905821A (de)

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2695232A (en) * 1950-07-08 1954-11-23 Kamyr Ab Apparatus for heating and controlling the temperature of a continuously operating cellulose digester
US2769710A (en) * 1954-01-12 1956-11-06 Cellulose Dev Corp Ltd Process for the continuous treatment of vegetable fibers
US2858212A (en) * 1956-02-13 1958-10-28 Condi Engineering Corp Wood chip feeders
US2858211A (en) * 1956-02-13 1958-10-28 Condi Engineering Corp Apparatus for wood chip digestion
US2872314A (en) * 1954-07-12 1959-02-03 Waldorf Paper Products Co Method of making pulp
US2905240A (en) * 1954-12-10 1959-09-22 Waldorf Paper Prod Co Apparatus for impregnating wood chips
US2938824A (en) * 1957-01-22 1960-05-31 Kamyr Ab Digestion apparatus and method
US2938825A (en) * 1953-01-30 1960-05-31 Babcock & Wilcox Co Method of resisting digester corrosion
US3041232A (en) * 1957-02-06 1962-06-26 Kamyr Ab Method of continuous cellulose digestion and digester apparatus for practicing said method
US3215588A (en) * 1963-08-15 1965-11-02 Lummus Co Continuous impregnation, cooking, and washing of fibrous material
US3313677A (en) * 1962-03-30 1967-04-11 Black Clawson Co Two-stage continuous digestion with removal of liquor in first stage and recirculation of liquor in second stage
US3313678A (en) * 1962-02-14 1967-04-11 Svenska Cellulose Aktiebolaget Bleaching of cellulose pulp in towers in completely filled and closed system
US3427218A (en) * 1964-07-10 1969-02-11 Kamyr Ab Method of performing counter-current continuous cellulose digestion
US3434920A (en) * 1965-10-07 1969-03-25 Frank B K Green Apparatus for continuous digesting
US4057461A (en) * 1975-06-02 1977-11-08 Kamyr Aktiebolag Method and apparatus for impregnation of fiber material by pressure pulsation
US5766418A (en) * 1996-09-13 1998-06-16 Ahlstrom Machinery Inc. Handling fibrous material used to produce cellulose pulp
US6336573B1 (en) 1998-04-06 2002-01-08 Andritz-Ahlstrom Inc. Hopper, or bin, screw feeder construction controlling discharge velocity profile
US20020129911A1 (en) * 2000-10-16 2002-09-19 Marcoccia Bruno S. Process and configuration for providing external upflow/internal downflow in a continuous digester
US10087578B2 (en) 2013-08-09 2018-10-02 Inbicon A/S Device for discharging pretreated biomass from higher to lower pressure regions

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE966918C (de) * 1952-05-29 1957-09-19 Kamyr Ab Vorrichtung zur Entnahme von Zellulosematerial aus Druckbehaeltern

Citations (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1186655A (en) * 1913-11-25 1916-06-13 Hydrolose Process Corp Process for obtaining fiber from wood and other substances.
GB150782A (en) * 1919-06-04 1920-09-06 Samuel Milne Improvements in and relating to stationary digesters and the like used in paper making and the like
FR519793A (fr) * 1916-10-19 1921-06-15 Waldhof Zellstoff Fab Procédé pour le traitement du bois et d'autres matières à teneur de cellulose
US1478614A (en) * 1919-03-04 1923-12-25 Cellulosepatenter As Process for digesting wood pulp
US1505934A (en) * 1921-12-01 1924-08-19 Olier Sa Ets A Device for the continuous treatment of ligneous materials for their transformation in cellulose
US1679336A (en) * 1926-10-25 1928-07-31 Chemipulp Process Inc Method and apparatus for continuous cooking of fibrous material
US1776761A (en) * 1928-04-02 1930-09-23 Morterud Einar Method for blowing out pulp digesters
US1856453A (en) * 1930-09-23 1932-05-03 Hercules Powder Co Ltd Method of treating fibrous materials
US1903962A (en) * 1930-11-08 1933-04-18 Dreyfus Henry Manufacture of cellulose or cellulosic products
US1918181A (en) * 1932-12-31 1933-07-11 Maine Seaboard Paper Company Digestion of fibrous material
US1933017A (en) * 1931-01-19 1933-10-31 Jansa Oscar Victor Emanuel Production of cellulose pulp
US1954012A (en) * 1930-02-17 1934-04-10 Lemberger Antonin Manufacture of cellulose and the like
US1980390A (en) * 1930-11-24 1934-11-13 Celanese Corp Apparatus for digesting cellulose material
US2008635A (en) * 1932-05-05 1935-07-16 Brubacher William Process of and apparatus for producing pulp
US2200034A (en) * 1935-08-08 1940-05-07 Albert D Merrill Method and apparatus for digesting cellulosic materials

Patent Citations (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1186655A (en) * 1913-11-25 1916-06-13 Hydrolose Process Corp Process for obtaining fiber from wood and other substances.
FR519793A (fr) * 1916-10-19 1921-06-15 Waldhof Zellstoff Fab Procédé pour le traitement du bois et d'autres matières à teneur de cellulose
US1478614A (en) * 1919-03-04 1923-12-25 Cellulosepatenter As Process for digesting wood pulp
GB150782A (en) * 1919-06-04 1920-09-06 Samuel Milne Improvements in and relating to stationary digesters and the like used in paper making and the like
US1505934A (en) * 1921-12-01 1924-08-19 Olier Sa Ets A Device for the continuous treatment of ligneous materials for their transformation in cellulose
US1679336A (en) * 1926-10-25 1928-07-31 Chemipulp Process Inc Method and apparatus for continuous cooking of fibrous material
US1776761A (en) * 1928-04-02 1930-09-23 Morterud Einar Method for blowing out pulp digesters
US1954012A (en) * 1930-02-17 1934-04-10 Lemberger Antonin Manufacture of cellulose and the like
US1856453A (en) * 1930-09-23 1932-05-03 Hercules Powder Co Ltd Method of treating fibrous materials
US1903962A (en) * 1930-11-08 1933-04-18 Dreyfus Henry Manufacture of cellulose or cellulosic products
US1980390A (en) * 1930-11-24 1934-11-13 Celanese Corp Apparatus for digesting cellulose material
US1933017A (en) * 1931-01-19 1933-10-31 Jansa Oscar Victor Emanuel Production of cellulose pulp
US2008635A (en) * 1932-05-05 1935-07-16 Brubacher William Process of and apparatus for producing pulp
US1918181A (en) * 1932-12-31 1933-07-11 Maine Seaboard Paper Company Digestion of fibrous material
US2200034A (en) * 1935-08-08 1940-05-07 Albert D Merrill Method and apparatus for digesting cellulosic materials

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2695232A (en) * 1950-07-08 1954-11-23 Kamyr Ab Apparatus for heating and controlling the temperature of a continuously operating cellulose digester
US2938825A (en) * 1953-01-30 1960-05-31 Babcock & Wilcox Co Method of resisting digester corrosion
US2769710A (en) * 1954-01-12 1956-11-06 Cellulose Dev Corp Ltd Process for the continuous treatment of vegetable fibers
US2872314A (en) * 1954-07-12 1959-02-03 Waldorf Paper Products Co Method of making pulp
US2905240A (en) * 1954-12-10 1959-09-22 Waldorf Paper Prod Co Apparatus for impregnating wood chips
US2858212A (en) * 1956-02-13 1958-10-28 Condi Engineering Corp Wood chip feeders
US2858211A (en) * 1956-02-13 1958-10-28 Condi Engineering Corp Apparatus for wood chip digestion
US2938824A (en) * 1957-01-22 1960-05-31 Kamyr Ab Digestion apparatus and method
US3041232A (en) * 1957-02-06 1962-06-26 Kamyr Ab Method of continuous cellulose digestion and digester apparatus for practicing said method
US3313678A (en) * 1962-02-14 1967-04-11 Svenska Cellulose Aktiebolaget Bleaching of cellulose pulp in towers in completely filled and closed system
US3313677A (en) * 1962-03-30 1967-04-11 Black Clawson Co Two-stage continuous digestion with removal of liquor in first stage and recirculation of liquor in second stage
US3215588A (en) * 1963-08-15 1965-11-02 Lummus Co Continuous impregnation, cooking, and washing of fibrous material
US3427218A (en) * 1964-07-10 1969-02-11 Kamyr Ab Method of performing counter-current continuous cellulose digestion
US3434920A (en) * 1965-10-07 1969-03-25 Frank B K Green Apparatus for continuous digesting
US4057461A (en) * 1975-06-02 1977-11-08 Kamyr Aktiebolag Method and apparatus for impregnation of fiber material by pressure pulsation
US5766418A (en) * 1996-09-13 1998-06-16 Ahlstrom Machinery Inc. Handling fibrous material used to produce cellulose pulp
US6336573B1 (en) 1998-04-06 2002-01-08 Andritz-Ahlstrom Inc. Hopper, or bin, screw feeder construction controlling discharge velocity profile
US20020129911A1 (en) * 2000-10-16 2002-09-19 Marcoccia Bruno S. Process and configuration for providing external upflow/internal downflow in a continuous digester
US10087578B2 (en) 2013-08-09 2018-10-02 Inbicon A/S Device for discharging pretreated biomass from higher to lower pressure regions

Also Published As

Publication number Publication date
FR905821A (fr) 1945-12-14
CH243348A (de) 1946-07-15

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