US3429773A - Continuous cellulose digester with charging device - Google Patents

Continuous cellulose digester with charging device Download PDF

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Publication number
US3429773A
US3429773A US447179A US3429773DA US3429773A US 3429773 A US3429773 A US 3429773A US 447179 A US447179 A US 447179A US 3429773D A US3429773D A US 3429773DA US 3429773 A US3429773 A US 3429773A
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United States
Prior art keywords
digester
casing
screen
liquid
chips
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Expired - Lifetime
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US447179A
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English (en)
Inventor
Johan C F C Richter
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Metso Fiber Karlstad AB
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Kamyr AB
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Publication of US3429773A publication Critical patent/US3429773A/en
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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
    • 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
    • D21C7/06—Feeding devices

Definitions

  • An upright continuous cellulose digester charging device wherein a conduit loop connects a cellulose feeder to a casing containing a screen and a rotary screw conveyor.
  • the casing opens into the area of the top of the digester, and the screen and the conduit loop connections in the casing are located at a level below the level of the casing opening into the area of the top of the digester. The device prevents excessive heat transfer from the digester back to the cellulose feeder.
  • the invention relates to an upright continuous cellulose digester with a charging device comprising a feeder operating against the digester pressure and a screening device located at a distance therefrom and consisting of a closed pressure-resistant casing, one end of which is steadily in open communication with the top of the digester and which casing encloses a rotary conveyor screw and a screen located along the latter, wherein the ends of a circulation conduit to which the feeder transfers comminuted cellulosic fiber material, such as wood chips, are connected to the casing of the screening device on opposite sides of the screen therein and in which conduit there is inserted a pump for returning to the feeder such liquid as is drawn off through said screen and for pumping a suspension of said fiber material to the screening device.
  • a drawback which under certain conditions may be present in previously known charging devices of said kind consists in that an excessive amount of heat is transferred from the digester to the circulating liquid and therefore to the feeder.
  • the object of the present invention is to counteract said inconvenient heat transfer. Said object is realized essentially by the characterising feature that the two ends of the circulation conduit are connected to the casing of the screening device at a level located below the lowermost point of the fiber material outlet of the casing directly communicating with the digester top.
  • the drawing shows an upright cylindrical digester 11, the upper end of which is adapted for being charged continuously with a comminuted cellulosic material, such as wood chips, which during its motion downwardly through the digester is treated in different ways and which is discharged at the lower end of the digester through a conduit 13.
  • a comminuted cellulosic material such as wood chips
  • a conduit 13 Inserted in the shell of the digester is a number of screen girdles through which various liquids can be drained oif the chips column.
  • Various conduits for supply of e.g. steam, digesting liquors, wash water etc. are also connected to the digester.
  • the invention is not restricted to any specific combination of treatments in the digester, but in the shown embodiment there is performed in the uppermost part of the digester a prehydrolyzing digestion in steam phase which at the liquid surface level 15 changes into a prehydrolyzing digestion in liquid phase. Below the level 15 there follows a delignifying digestion by means of liquor flowing in counter-current through the middle part of the digester, and in the lowermost part of the digester there takes place a partial washing-out of the digesting liquor by means of wash water supplied to the lower end of the vessel and driven counter-currently up through the chips column. In the middle delignifying zone a temperature of the order of 170 C. should be maintained and therefore the digester is held under a correspondingly high pressure, e.g. of the order of 150 pounds per square inch.
  • the objects of the charging device is to charge chips etc. continuously into the upper end of the digester against the action of said high pressure.
  • the charging device consists of two units connected to each other by means of tube conduits, one unit consisting of a screening device located close to the digester top and in its entirety designated by the numeral 17, and the other unit consisting of a feeder designated in its entirety by 19 and usually located at a lower level than the screening device.
  • the feeder 19 which may be of any known type, is shown as a rotary feeder essentially consisting of a cylindrical or conical rotor 21 and a casing 23 therefor, having four connections 25, 27, 29 and 31 distributed around the circumference.
  • the rotor is provided with a diametrically through-going pocket 33 which from the shown vertical filling position can be turned into an inclined position in which its two ends are shut off by the casing 23 and from there on into a horizontal emptying position.
  • Attached to the upper connection 25 is a chute 35 having a perforated wall enclosed by a container 37 which is held partly filled with liquid. Through the chute there pass chips emanating from the chips bin 39 and having been fed by the charging device 411 into the steaming vessel 43 which is held under a low pressure, e.g.
  • the pocket forms apart of a circulation loop held under digester pressure and formed by two conduit branches 51, 53 and the screening device 17 at the top of the digester.
  • a pump 55 inserted in the return conduit 53 (which only carries liquid) the chips-liquid-mixture in the pocket 33 is pumped up through the conduit 51 to the screening device 17 where the chips are delivered, whereas the liquid is recirculated.
  • the liquid content of the container 37 around the chute increases.
  • the level therein is maintained constant by liquid being discharged into a collecting tank 57 under control of a valve 59 and a level feeling means.
  • the screening device 17 at the digester top comprises a pressure-resistant casing 61 which encloses a cylindrical screen 63.
  • the casing is composed of a cylindrical part 65 having the same diameter as the screen 63 and forming an axial extension thereof, and a part 67 of a greater diameter surrounding the screen 63 in such a manner that an isolated space is formed on the outside of the screen 63.
  • the part 67 preferably forms a spherically widened part which is joined to the lower end of the cylindrical part 65 of the casing.
  • a motor-driven feed screw 69 Arranged inside the screen 61 and the casing part 65 and concentric thereto is a motor-driven feed screw 69, the shaft 71 of which extends through the plane or bulging ends of the casing 61 and is sealed thereto.
  • the conduit 51 through which the chips-liquid-mixture is supplied opens out in the casing 61 at the lower end and thereof and on the inner side of the screen 63, whereas the conduit 53 is connected to the widened part 67 surrounding the screen 63 and therefore is capable of returning to the feeder 19 merely such liquid as has drained through the screen 63.
  • the chips are advanced by the feed screw 69 in the axial direction thereof at first along and past the screen 63 and then through the cylindrical casing part 65 on to a lateral outlet 73 positioned at or near the upper end of the casing and connected by a flange connection to the tapering top part of the digester.
  • the screening device is inverted in comparison to a previously commonly used design, i.e. the feed direction of the chips therein is not downward as in the digester, but is upward, and the screening device has its communication with the digester located at a high level, whereas the chips are supplied to the screening device at a low level.
  • the screen and the conveyor screw are inclined to the horizontal plane by an angle of between 30 and 60 degrees.
  • the chips outlet 73 at the upper end of the casing 61 may be placed substantially straight above the centre of the digester, as shown in the drawing, so that the chips drop down directly into the digester in the shortest possible path.
  • conduits connected to the lower end of the casing of the screening device are situated on a level which is lower than the lowermost point of the chips outlet 73, and the screen 63 is also situated in its entirety distant from and on a level lower than said lowermost point of the chips outlet 73.
  • the distance between said outlet 73 and said screen 63 is of the order of the axial length of the screen 63 or at least a third of the axial length of the feed screw 69.
  • the screening device should preferably be so designed that the length and the inclination of its casing areso chosen relatively to the width measured at right angles to the axis of the feed screw that a free liquid surface can form at a level which is located below the level of the chips outlet of the casing but above the screen 63 and also above the two connection points of the circulation conduit 51, 53 upon the casing.
  • the embodiment shown in the drawing possesses said feature, and as seen therein the liquid surface 75 forms a border surface which prevents the steam present thereabove and supplied to the digester top through the conduit 77, from penetrating down to the screen 63 and heating the liquid flowing in the conduit 53 back to the feeder 19.
  • the surface level 75 is maintained substantially constant in a position coincident with a middle part of the feed screw 69 and the cylindrical casing part 65.
  • the device used therefor consists of a level feeding means designated by the symbol 79, which means acts upon a control valve 81 inserted in a conduit 83 through which liquid from the collecting tank 57 is returned by means of a pump 85 to the screening device 17.
  • the quantity of liquid carried with the chips When rising above the liquid surface level 75 of the screening device is replaced by liquid from the conduit 87, which liquid is supplied to the tank 57 in such a quantity that the level therein is maintained constant.
  • Said liquid may be either water or some treating liquid, such as digesting liquor, agreeing with the treatment to which the chips are to be subjected immediately after their introduction into the digester.
  • the thread of the feed screw 69 is left out, so that the chips are lifted up and out of the liquid by the action of the rising lower part of the chips column. Somewhat above the liquid surface 75 the screw feeder 69 again acts directly upon the chips in order to feed them towards the outlet 73.
  • the charging device shown may also be used for a digester having no gas or steam filling and the overpressure of which is maintained by hydraulic compression. Then a free liquid surface 75 is not formed and the valve 81 should be controlled otherwise, e.g. by the pressure of the digester.
  • a digester provided with the new charging device can be operated either with or without a gas phase at the top, and conversion from one to the other kind of operation may easily take place.
  • the steaming vessel 43 may be replaced by an upright container in which steaming as well as impregnation of the chips with digesting liquor take place.
  • the feeder may be of the reciprocating or plunger type.
  • An upright continuous cellulose digester charging device comprising a feeder operating against the digester pressure and a screening device located at a distance from said feeder, said screening device comprising a closed pressure-resistant casing, one end of which is in steadily open communication with the top of the digester said casing enclosing a rotary conveyor screw and a screen completely surrounding part of said screw, a circulation conduit to which said feeder transfers comminuted cellulosic fiber material, such as wood chips, being connected to said casing on opposite sides of said screen therein, a pump in said circulation conduit for returning to said feeder such liquid as is drawn off through said screen and for pumping a suspension of said fiber material to the screening device, the said circulation conduit being connected to said casing of said screening device at a level located below the lowermost point of the end of said casing directly communicating with the digester top.
  • a digester charging device controls or maintains constant said liquid surface level in a position coincident with a middle part of said conveyor screw.
  • a digester charging device in which the thread of said conveyor screw is left out along a comparatively small portion of the same in the area where said free liquid surface is maintained.
  • a digester charging device in which the part of said casing located next to said casing end is cylindrical, in which said screen enclosing said conveyor screw and located next to said fiber material inlet is cylindrical, lies in the extension of and has the same diameter as said first-mentioned cylindrical casing part, and in which said casing has a part of greater diameter enclosing said screen.
  • An upright continuous cellulose digester charging device comprising a feeder, a screening device comprising a closed pressure-resistant casing, one end of which opens into the top of said digester, a screen, a rotary screw conveyor located within said casing and enclosed at its lower end by said screen, and conduit connections opening into said casing, said screen and said conduit connections located at a level below the lowermost point of said end of said casing opening into the top of said digester, and a conduit loop consisting of a feed conduit and a liquid return conduit and a pump inserted in said return conduit, said conduit loop connecting said conduit connections of said screening device to said feeder.

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US447179A 1964-04-16 1965-04-12 Continuous cellulose digester with charging device Expired - Lifetime US3429773A (en)

Applications Claiming Priority (1)

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SE4682/64A SE300755B (fi) 1964-04-16 1964-04-16

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US (1) US3429773A (fi)
DE (1) DE1517193C2 (fi)
FI (1) FI45879C (fi)
SE (1) SE300755B (fi)

Cited By (28)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3898124A (en) * 1971-11-18 1975-08-05 Asea Ab Automatic control of a continuous digester, including level, concentration, and flow meters
DE2503400A1 (de) * 1974-01-31 1975-08-14 Kamyr Inc Verfahren zum zufuehren von vergasungsstoffen in einen druckvergaser und vorrichtung zur durchfuehrung dieses verfahrens
DE2535306A1 (de) * 1974-08-08 1976-02-19 Kamyr Inc Verfahren zum zufuehren von kohlenstaub oder aehnlichem zu einer reaktionskammer und vorrichtung zur durchfuehrung dieses verfahrens
US3950146A (en) * 1974-08-08 1976-04-13 Kamyr, Inc. Continuous process for energy conserving cooperative coal feeding and ash removal of continuous, pressurized coal gasifiers and the like, and apparatus for carrying out the same
US3982789A (en) * 1974-07-16 1976-09-28 Kamyr, Inc. Process and apparatus for conveying large particle mined coal, oil shale, ore, etc. from underground mines or from strip mines via a pipeline
US4017270A (en) * 1974-01-31 1977-04-12 Kamyr, Inc. Coal gasification process with improved procedures for continuously feeding lump coal under pressure
US4033811A (en) * 1975-06-09 1977-07-05 Stig Gloersen Method and apparatus for filling of fiber material and liquid to steam phase in treatment vessel
US4061193A (en) * 1975-09-15 1977-12-06 Kamyr, Inc. Method and apparatus for digesting cellulose material without screening digesting liquid withdrawn through the digester top
DE2629209A1 (de) * 1976-06-29 1978-01-12 Kamyr Inc Verfahren und vorrichtung zum foerdern von im bergbau gewonnenem material zu einer von der abbaustelle entfernten stelle
US4073629A (en) * 1974-07-30 1978-02-14 Kamyr Inc. Coal gasification process with improved procedure for continuously discharging ash particles and apparatus therefor
US4078964A (en) * 1973-12-10 1978-03-14 Kamyr Ab Method and apparatus for filling a pressure treatment vessel with a fiber material and liquid mixture
US4125384A (en) * 1977-03-03 1978-11-14 Kamyr Inc. Method and apparatus for continuously feeding solid particles into a pressurized container
DE2758985A1 (de) * 1977-12-30 1979-07-05 Kamyr Inc Verfahren und vorrichtung zum foerdern von im bergbau gewonnenem material zu einer von der abbaustelle entfernten stelle
US4174997A (en) * 1973-09-03 1979-11-20 Kamyr Aktiebolag Method and apparatus for continuous hydrolysis of cellulosic fiber material
US4187043A (en) * 1974-07-23 1980-02-05 Kamyr, Inc. Method and apparatus for boosting pressure in a coal pipeline
US4260225A (en) * 1979-06-18 1981-04-07 The Dow Chemical Company Energy saving radiant insulative device
US4701266A (en) * 1984-04-13 1987-10-20 Hycrude Corporation Solids dewatering apparatus and process
WO1995021287A1 (en) * 1994-02-01 1995-08-10 Kamyr, Inc. Chip bin assembly including a hollow transition with one dimensional convergence and side relief
US5500083A (en) * 1994-02-01 1996-03-19 Kamyr, Inc. Method of feeding cellulosic material to a digester using a chip bin with one dimensional convergence and side relief
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
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
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
US20160145797A1 (en) * 2014-11-26 2016-05-26 International Paper Company Continuous digester and feeding system
US9574302B2 (en) * 2011-04-08 2017-02-21 Rge Pte Ltd Method and system for efficient production of dissolving pulp in a kraft mill producing paper grade pulp with a continuous type digester

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4343730C1 (de) * 1993-12-21 1995-03-02 Deggendorfer Werft Eisenbau Schleuseneinheit für Zellstoffaufschließanlagen und deren Verwendung

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2803540A (en) * 1956-03-06 1957-08-20 Condi Engineering Corp Wood chip digestion
US2872314A (en) * 1954-07-12 1959-02-03 Waldorf Paper Products Co Method of making pulp
US2999784A (en) * 1957-07-10 1961-09-12 Escher Wyss Gmbh Process and apparatus for the treatment of fibrous materials in the production of cellulose or semi-cellulose

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2872314A (en) * 1954-07-12 1959-02-03 Waldorf Paper Products Co Method of making pulp
US2803540A (en) * 1956-03-06 1957-08-20 Condi Engineering Corp Wood chip digestion
US2999784A (en) * 1957-07-10 1961-09-12 Escher Wyss Gmbh Process and apparatus for the treatment of fibrous materials in the production of cellulose or semi-cellulose

Cited By (33)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3898124A (en) * 1971-11-18 1975-08-05 Asea Ab Automatic control of a continuous digester, including level, concentration, and flow meters
US4174997A (en) * 1973-09-03 1979-11-20 Kamyr Aktiebolag Method and apparatus for continuous hydrolysis of cellulosic fiber material
US4078964A (en) * 1973-12-10 1978-03-14 Kamyr Ab Method and apparatus for filling a pressure treatment vessel with a fiber material and liquid mixture
DE2503400A1 (de) * 1974-01-31 1975-08-14 Kamyr Inc Verfahren zum zufuehren von vergasungsstoffen in einen druckvergaser und vorrichtung zur durchfuehrung dieses verfahrens
US4017270A (en) * 1974-01-31 1977-04-12 Kamyr, Inc. Coal gasification process with improved procedures for continuously feeding lump coal under pressure
US4082368A (en) * 1974-07-16 1978-04-04 Kamyr Inc. Method and apparatus for hydraulic transmission of coal, oil shale, mineral ores, etc. from the face to the surface of underground mines
US3982789A (en) * 1974-07-16 1976-09-28 Kamyr, Inc. Process and apparatus for conveying large particle mined coal, oil shale, ore, etc. from underground mines or from strip mines via a pipeline
US4187043A (en) * 1974-07-23 1980-02-05 Kamyr, Inc. Method and apparatus for boosting pressure in a coal pipeline
US4073629A (en) * 1974-07-30 1978-02-14 Kamyr Inc. Coal gasification process with improved procedure for continuously discharging ash particles and apparatus therefor
US3950147A (en) * 1974-08-08 1976-04-13 Kamyr, Inc. Process for feeding coal to a fluidized bed or suspended particle pressurized processing chamber and apparatus for carrying out the same
US3950146A (en) * 1974-08-08 1976-04-13 Kamyr, Inc. Continuous process for energy conserving cooperative coal feeding and ash removal of continuous, pressurized coal gasifiers and the like, and apparatus for carrying out the same
DE2535306A1 (de) * 1974-08-08 1976-02-19 Kamyr Inc Verfahren zum zufuehren von kohlenstaub oder aehnlichem zu einer reaktionskammer und vorrichtung zur durchfuehrung dieses verfahrens
US4033811A (en) * 1975-06-09 1977-07-05 Stig Gloersen Method and apparatus for filling of fiber material and liquid to steam phase in treatment vessel
US4061193A (en) * 1975-09-15 1977-12-06 Kamyr, Inc. Method and apparatus for digesting cellulose material without screening digesting liquid withdrawn through the digester top
DE2629209A1 (de) * 1976-06-29 1978-01-12 Kamyr Inc Verfahren und vorrichtung zum foerdern von im bergbau gewonnenem material zu einer von der abbaustelle entfernten stelle
US4125384A (en) * 1977-03-03 1978-11-14 Kamyr Inc. Method and apparatus for continuously feeding solid particles into a pressurized container
DE2758985A1 (de) * 1977-12-30 1979-07-05 Kamyr Inc Verfahren und vorrichtung zum foerdern von im bergbau gewonnenem material zu einer von der abbaustelle entfernten stelle
US4260225A (en) * 1979-06-18 1981-04-07 The Dow Chemical Company Energy saving radiant insulative device
US4701266A (en) * 1984-04-13 1987-10-20 Hycrude Corporation Solids dewatering apparatus and process
WO1995021287A1 (en) * 1994-02-01 1995-08-10 Kamyr, Inc. Chip bin assembly including a hollow transition with one dimensional convergence and side relief
US5500083A (en) * 1994-02-01 1996-03-19 Kamyr, Inc. Method of feeding cellulosic material to a digester using a chip bin with one dimensional convergence and side relief
US5628873A (en) * 1994-02-01 1997-05-13 Ahlstrom Machinery Inc. Chip bin assembly including a hollow transition with one dimensional convergence and side relief
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
US5882477A (en) * 1997-02-10 1999-03-16 Ahlstrom Machinery, Inc. Continuous digester with a low temperature gas-phase
US6024837A (en) * 1997-02-10 2000-02-15 Ahlstrom Machinery Inc. Low temperature gas phase continuous digester
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
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
US9574302B2 (en) * 2011-04-08 2017-02-21 Rge Pte Ltd Method and system for efficient production of dissolving pulp in a kraft mill producing paper grade pulp with a continuous type digester
US20160145797A1 (en) * 2014-11-26 2016-05-26 International Paper Company Continuous digester and feeding system
US9644317B2 (en) * 2014-11-26 2017-05-09 International Paper Company Continuous digester and feeding system

Also Published As

Publication number Publication date
DE1517193C2 (de) 1974-03-21
DE1517193B1 (de) 1970-10-15
SE300755B (fi) 1968-05-06
FI45879C (fi) 1972-10-10
FI45879B (fi) 1972-06-30

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