US3144381A - Continuously operable vertical digester for cooking pre-impregnated fibrous raw materials - Google Patents

Continuously operable vertical digester for cooking pre-impregnated fibrous raw materials Download PDF

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Publication number
US3144381A
US3144381A US123162A US12316261A US3144381A US 3144381 A US3144381 A US 3144381A US 123162 A US123162 A US 123162A US 12316261 A US12316261 A US 12316261A US 3144381 A US3144381 A US 3144381A
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United States
Prior art keywords
digester
shaft
raw materials
fibrous raw
cooking
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Expired - Lifetime
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US123162A
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English (en)
Inventor
Simon Ludwig
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JM Voith AG
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JM Voith AG
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Publication date
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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
    • D21C7/00—Digesters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01B—BOILING; BOILING APPARATUS ; EVAPORATION; EVAPORATION APPARATUS
    • B01B1/00—Boiling; Boiling apparatus for physical or chemical purposes ; Evaporation in general

Definitions

  • This invention relates to a continuously operable vertical digester for cooking pro-impregnated fibrous raw materials for the manufacture of chemical or semi-chemical pulp at temperatures over 100 C. and under pressure.
  • the invention relates to a continuously operable vertical digester for cooking pro-impregnated fibrous raw materials for the manufacture of chemical or semi-chemical woodpulp at temperatures above 100 C. and under pressure, which digester comprises a centrically mounted, driven vertical shaft, a digester bottom having one or more discharge openings which are suitably connected to one or more cylindrical or conical screw-type extruders or the like and/ or a disintegrator, which digester is characterized in that the shaft extends throughout the digester vessel Patented Aug; 11, 1964 from top to bottom and is mounted in known manner in an axial bearing on the cover of the vessel and guided in a radial bearing below the bottom of the vessel, and that a discharge device carrying the entire pulp column is supported by the shaft next to the digester bottom.
  • the diameter of the shaft may be larger at the top end than at the bottom end of the digester.
  • the shaft may be hollow and formed with holes, through which the steam introduced into the shaft enter
  • FIG. 1 is a longitudinal sectional view showing one embodiment of a digester according to the invention.
  • FIG. 2 is a sectional view taken on line ab of FIG. 1.
  • FIGS. 3, 4 and 5 are diagrammatic views showing modifications.
  • the vertical cylindrical digester 1 operates continuously in the vapor phase and serves for cooking pre-impregnated fibrous raw materials for manufacturing chemical or semi-chemical pulp at temperatures over C. and under pressure.
  • the digester may also be used for pretreating any fibrous raw material.
  • the material to be cooked is introduced into the digester 1 from a hopper 35.
  • the Weight of the material 3 to be cooked in the digester loads the rotating outlet device 4, which is secured to a continuous, vertical shaft 5 having a controllable speed.
  • the shaft 5 is supported by an axial bearing (step bearing) 6 carried on the cover of the digester 1.
  • a lower bearing 7 also disposed outside the digester serves as a guide bearing for the shaft. Owing to this arrangement the continuous vertical shaft 5 is stressed only in tension and torsion rather than in fiexion because the load of the discharge device 4 is uniformly divided by the material 3 to be boiled. For this reason the volume of the digester may be large without involving structural difficulties because the digester having a given height may be given an appropriate diameter.
  • the material 3 to be boiled must slowly descend in the digester 1. This descent must be uniform in order to ensure a uniform cooking.
  • the discharge device 4 must continuously and uniformly remove the cooked material from the digester.
  • the chips of raw material descend in the digest 1 under the action of the force of gravity, which can act on the material 3 being cooked without hindrance in all cross-sections unless the chips form bridges.
  • the available cross-section of the digest 1 must be downwardly enlarged in known manner to provide for a progressive relief of the chips of raw material.
  • the digester is provided with a device 8 of any known type for indicating the level of the material to be cooked. It is also suitable to provide the continuous vertical shaft 5 at its top end with stirring arms 9 for leveling the material 3 to be cooked.
  • a steam pipe 11 is connected to the digester approximately in the middle and also below the outlet device 4, e.g. by means of a ring conduit provided with a plurality of supply connections, in order to equalize the steam pressure in the digester.
  • automatic device 12 is provided to eliminate air and gasses from the digester 1.
  • the shaft is hollow and provided with holes, steam can be supplied also from the top by means of the conduit indicated with dash-and-dot lines.
  • the rotating outlet device 4 driven by the shaft 5 at, e.g. 20-30 revolutions per minute, consists of a disc 13 having approximately the same diameter as the bottom of the digester, and two or more stirring arms 14 which are disposed below the disc 13 and curved opposite to the direction of rotation 15.
  • the stirring arms 14 are rigidly secured to the underside of the disc 13.
  • Pegs or pins 16 in the form of pyramids, cones, prisms, cylinders or the like are secured to the top face of the disc 13.
  • the disc 13 is also formed with through holes 17. During the rotation of the outlet device 4, the pins mix the cooked chips of the raw material.
  • these chips are comminuted to some extent at the cooking temperature because the weight of the material 3 being cooked presses the cooked material onto the disc 13. Owing to the friction between the chips and between the chips and the digester wall the material being cooked cannot rotate in synchronism with the disc 13. Owing to the pressure exerted by the material 3 being cooked on the top face of the disc 13 and owing to the force of gravity, the cooked and comminuted raw material falls through the holes 17 into the space between the disc and the digester bottom, in which space the stirrer arms 14 rotate in the direction 15. They are preferably curved opposite to the direction of rotation.
  • the material is urged outwardly towards the discharge opening 19 in the direction of the arrow 18 and flows through a discharge conduit 20 into a conical or cylindrical screw-type extruder 21, which is radially or tangentially disposed.
  • the rotating screw 22 which is driven, e.g. by an electric motor having a controllable speed, compresses the material and feeds it to the adjustable discharge opening 23, through which it is extruded from the extruder 21.
  • the material is blown out in the direction of the arrow 24 by means of steam.
  • the shaft 5 is connected by a clutch 27 to a stub shaft of the transmission 28, which is driven by an additional electric motor.
  • FIG. 3 shows another design of the digester providing for a relief of the chips of the raw material in the digester.
  • the digester 1a is assembled from a plurality of relatively short cylindrical parts. The diameter of each part is larger than that of the part preceding in the direction of flow. This digester provides for a stepwise enlargement of the free cross-section of the digester.
  • FIG. 4 shows another form of the digester 1b, which has the shape of an upright cone providing for a continuous increase of the free cross-section of the digester from top to bottom to afford a progressive relief of the chips of the raw material.
  • FIG. 5 shows a digester in which features of the digesters of FIGS. 3 and 4 are combined.
  • This digester 10 consists of a plurality of conical parts and the top diameter of each part is larger than the bottom diameter of the part preceding in the direction of flow. This provides for an increase of the free cross-section of the digester in the downward direction and for a stepwise and continuous relief of the raw material.
  • the digester may have a conical shaft 5 (FIG. 1) or a cylindrical shaft 5a (FIG. 3), 5b (FIG. 4) or 5c (FIG. 5).
  • This conical or cylindrical shaft is desirably provided with a plurality of projections, pins or the like, which extend substantially at right angles to the shaft and prevent a formation of bridges by the material being cooked.
  • the invention provides an arrangement of the shaft and of the discharge device carried thereby in which the shaft is stressed only in tension and possibly in torsion and the bearings disposed outside the digester are exposed only to the environmental temperature and are easily accessible for maintenance.
  • the features of the invention enable the construction of reliable digesters having a large volume without involving design difficulties.
  • V/hat is claimed is:
  • a vertical digester for the continuous cooking of preimpregnated fibrous raw materials in the manufacture of pulp at temperatures above C. and under pressure, comprising a digester vessel adapted to contain a pulp column and having a top and a bottom, said bottom having at least one outlet, a vertical shaft coaxially disposed in and extending throughout said digester vessel and through the top and bottom thereof, an axial thrust bearing for said shaft located above said top, a radial bearing for said shaft disposed below said bottom, drive means for rotating said shaft in said axial and radial bearings, a discharge device fixed to and carried by said shaft above and adjacent to said bottom, said discharge device comprising a disc secured to said shaft having perforations as well as projections provided on its top face and having approximately the same diameter as the digester bottom, and at least two stirrer arms rigidly secured to said disc on the underside thereof and serving for pushing the digested chips collected at the bottom of the vessel radially outwards.
  • a vertical digester for the continuous cooking of preimpregnated fibrous raw materials in the manufacture of pulp at temperatures above 100 C. and under pressure, comprising a digester vessel adapted to contain a pulp column and having a top and a bottom, said bottom having at least one outlet, a vertical shaft coaxially disposed in and extending throughout said digester vessel and through the top and bottom thereof, an axial thrust bearing for said shaft located above said top, a radial bearing for said shaft disposed below said bottom, drive means for rotating said shaft in said axial and radial bearings, a discharge device fixed to and carried by said shaft above and adjacent to said bottom and the diameter of said shaft being larger at the top than at the bottom of said digester vessel.
  • a vertical digester for the continuous cooking of preimpregnated fibrous raw materials in the manufacture of pulp at temperatures above 100 C. and under pressure, comprising a digester vessel adapted to contain a pulp column and having a top and a bottom, said bottom having at least one outlet, a vertical shaft coaxially disposed in and extending throughout said digester vessel and through the top and bottom thereof, an axial thrust bearing for said shaft located above said top, a radial bearing for said shaft disposed below said bottom, drive means for rotating said shaft in said axial and radial bearings, a discharge device fixed to and carried by said shaft above and adjacent to said bottom, said shaft being hollow and provided with holes so that steam can pass through said holes into the interior of said digester vessel.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Paper (AREA)
US123162A 1960-07-20 1961-07-11 Continuously operable vertical digester for cooking pre-impregnated fibrous raw materials Expired - Lifetime US3144381A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
AT558360A AT221929B (de) 1960-07-20 1960-07-20 Lotrechtstehender, kontinuierlich arbeitender Kocher zum Aufschließen vorimprägnierter, faserhaltiger Rohmaterialien

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US3144381A true US3144381A (en) 1964-08-11

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US (1) US3144381A (de)
AT (1) AT221929B (de)
FR (1) FR1295266A (de)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1415433A (en) * 1919-12-16 1922-05-09 Engel Henri Apparatus for the extraction of oils and the like
US2027131A (en) * 1931-07-28 1936-01-07 Charles B Upton Cooker
US2516447A (en) * 1947-02-24 1950-07-25 Elmer R Burling Method and apparatus for chemical treatment
US2540706A (en) * 1947-05-22 1951-02-06 Texas Co Process and apparatus for effecting catalytic reactions
US2858211A (en) * 1956-02-13 1958-10-28 Condi Engineering Corp Apparatus for wood chip digestion
US2960161A (en) * 1957-05-16 1960-11-15 John C F C Richter Device for discharging materials from vessels

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1415433A (en) * 1919-12-16 1922-05-09 Engel Henri Apparatus for the extraction of oils and the like
US2027131A (en) * 1931-07-28 1936-01-07 Charles B Upton Cooker
US2516447A (en) * 1947-02-24 1950-07-25 Elmer R Burling Method and apparatus for chemical treatment
US2540706A (en) * 1947-05-22 1951-02-06 Texas Co Process and apparatus for effecting catalytic reactions
US2858211A (en) * 1956-02-13 1958-10-28 Condi Engineering Corp Apparatus for wood chip digestion
US2960161A (en) * 1957-05-16 1960-11-15 John C F C Richter Device for discharging materials from vessels

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Publication number Publication date
AT221929B (de) 1962-06-25
FR1295266A (fr) 1962-06-01

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