US3388038A - Apparatus for charging a continuous digester - Google Patents

Apparatus for charging a continuous digester Download PDF

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Publication number
US3388038A
US3388038A US416398A US41639864A US3388038A US 3388038 A US3388038 A US 3388038A US 416398 A US416398 A US 416398A US 41639864 A US41639864 A US 41639864A US 3388038 A US3388038 A US 3388038A
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United States
Prior art keywords
charging
liquid
container
digester
conduit
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Expired - Lifetime
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US416398A
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English (en)
Inventor
Hander Nils
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.)
Nordiska Armaturfabrikerna AB
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Nordiska Armaturfabrikerna AB
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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
    • D21C7/06—Feeding devices

Definitions

  • the present invention relates to methods and apparatus for charging a lignin-containing fibrous material, such as wood chips, into a continuously operating digester, with the possibility of pretreating this material under conditions which both physically and chemically are different from the process conditions in the digester.
  • pretreatment or impregnation of the fibrous material can be carried out independently of the conditions in the digester, including the possibility of varying the physical conditions (pressure, temperature, time) as well as the chemical conditions (chemical composition and con centration)
  • hitherto used charging devices rotating valves, metering rums etc.
  • the lignin-containing raw material and a pretreating liquid are introduced into a charging container which is brought to the desired pressure and prior to introduction of the material into the digester is brought to the same pressure as the digester by means of a cooking liquid circulation system, whereupon the pretreated material is introduced into the digester by the cooking liquid circulating in the circulation system.
  • a charging container which is brought to the desired pressure and prior to introduction of the material into the digester is brought to the same pressure as the digester by means of a cooking liquid circulation system, whereupon the pretreated material is introduced into the digester by the cooking liquid circulating in the circulation system.
  • a feeding device of known type e.g. a screw, which feeds the material toward a portion States Patent 0 3,388,@38 Patented June 11, 1868 "ice of the charging container through which the circulating digesting liquid flows.
  • the outlet of the feeding device is preferably so formed that no substantial admixture of the p-retreating liquid and the flowing digesting liquid occurs.
  • the raw material is passed by the feeding device from the pretreating liquid temperature region to the digesting liquid temperature region at a rate such that heat transfer in a direction opposite to that of the feed of the container contents cannot take place.
  • pretreating liquid is continuously introduced into the container.
  • the temperature in the charging container is independent of the temperature of the digesting liquid.
  • the time of pretreating under pressure in the liquid phase can be predetermined as desired.
  • the pretreating liquid may be of a composition different from that of the digesting liquid.
  • the digester 1 comprises an elongate vertical tube which at its lower end has means 2 for withdrawing the pulped material to the outlet conduit 3.
  • a screen 4 digesting liquid is withdrawn via the conduit system 5 with valves 6 by a circulating pump 7 to the heat exchanger 8 where the digesting liquid is heated by steam suplied through the conduit 9 with valve 10, the resulting steam condensate being withdrawn through conduit 11.
  • the heated digesting liquid is returned to the digester top through conduit 12, three-way valve 13, conduits 14, or conduits 16, 17, three-way valve 18 and conduit 19.
  • Charging of wood-chips and pretreatment thereof are carried out by the aid of two charging containers 20, 21 which have each an outlet portion 22 and 23, respectively, interposed between the conduits 14, 15 and 16, 17, respectively, so that the circulating digesting liquid flows through the outlet portion 22 or 23 depending on the setting of the three-way-valves 13, 18.
  • the valves 13, 18 are set so that the digesting liquid flows from the valve 13 through conduit 14. outlet portion 23 of container 21 and conduit 15 to valve 18.
  • Each charging container is also connected to a chip conduit 24 and 25, respectively, having a suitable valve means 26, 27, preferably a ball valve.
  • the ball valve 26 of the container is open so that wood chips can enter this container which as mentioned is disconnected from the digesting liquid circulation.
  • the ball valve 27 of container 21, however, is closed, and this container is operating to feed chips into the digester through the digesting liquid circulation conduit.
  • the container 21 is provided with a screw feeder 28 in its bottom portion above a screen bottom 29.
  • the screw feeder 28 extends partly into the outlet portion 23 but not up to the mouths of the conduits 16, 17 so that a free space is formed in front of the screw end.
  • the container 20 has a similar screw 30 and screen bottom 31. The screws are driven by motors which are not shown.
  • one container is filled with chips while the other serves to charge chips into the digester, the screw 28 feeding the chips into the outlet portion 23 where they are entrained by the flowing digesting liquid to the conduit 19 and thus enter the digester 1 together with the liquid.
  • valves 39, 45, 46 are closed, While valve 40 is open, so that impregnating liquid can be introduced into the container 20 from a tank (not shown) through conduits 37, 38 while charging container 21) is being filled with chips.
  • valve 49 is set so that the pump 51 and conduit 51 communicate with the container 21 through conduit 47, so that impregnating liquid is pumped to this charging container at a rate corresponding to the amount of material charged to the digester.
  • the feed of the impregnated cellulosic material by means of feed screw 28 prevents equalization of tempera ture between the impregnating liquid and the digesting liquid.
  • valves 13, 18 are set so that the digesting liquid flows through the outlet portion 22 of the container 28, whereby this container is brought to the digester pressure.
  • the feed screw 30 is started to start the charging of chips.
  • the valve 49 is set to introduce liquid into the container 20 at a rate corresponding to the rate of removal of the material.
  • the charging container 21 is filled with impregnating liquid under digester pressure.
  • the liquid is removed by opening valve 46, whereby the pressure is also lowered.
  • the ball valve 27 and the valve 40 can now be opened and the charging container 21 is filled with chips, which is simultaneously impregnated therein.
  • Fresh digesting liquid is supplied to the digester through the conduit 57 with valve 58.
  • the arrangement according to this invention provides a possibility of carrying out, with mechanically simple means, a completely continuous charging of chips to a continuously operating digester and at the same time it enables a pretreatment of the chips to be carried out in a simple manner With an impregnating liquid of a composition different from that of the digesting liquid and under conditions diflering from those prevailing in the digester.
  • the invention is not limited to the embodiment illustrated and described.
  • more than two charging containers may be used, which are arranged to be connected one or more at a time to the circulation system. It is also pointed out that in some cases it may be suitable to leave a certain amount of pretreated chips in a charging container before the next chip filling step, in order to be able to start the charging of chips at an earlier time from this container and yet obtain sutlicient time for impregnating the freshly supplied chips under pressure.
  • a system for charging cellulosic material to a continuously operating digester comprising a charging container, a screw feeder horizontally positioned in the bottom of the charging container, a digester liquid recirculation conduit, means for introducing cellulosic material into the charging container, means for feeding treating liquid into the first-mentioned means, and means clefining an outlet for the screw feeder connected to the digester liquid recirculation conduit so that the impregnated cellulosic material is admixed with the digesting liquid in said conduit without substantial admixture of the treating liquid in the charging container and said digesting liquid.

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US416398A 1963-12-06 1964-12-07 Apparatus for charging a continuous digester Expired - Lifetime US3388038A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
SE13558/63A SE302882B (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1963-12-06 1963-12-06

Publications (1)

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US3388038A true US3388038A (en) 1968-06-11

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US416398A Expired - Lifetime US3388038A (en) 1963-12-06 1964-12-07 Apparatus for charging a continuous digester

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US (1) US3388038A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
SE (1) SE302882B (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5795438A (en) * 1996-11-04 1998-08-18 Ahlstrom Machinery Inc. Method and apparatus for feeding multiple digesters
US5985096A (en) * 1997-09-23 1999-11-16 Ahlstrom Machinery Inc. Vertical pulping digester having substantially constant diameter
US20060070709A1 (en) * 2002-05-21 2006-04-06 Vidar Snekkenes Method for the continuous cooking of wood raw material for cellulose pulp

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2996422A (en) * 1958-04-23 1961-08-15 Ed Jones Corp Digestion of cellulosic material
US3041232A (en) * 1957-02-06 1962-06-26 Kamyr Ab Method of continuous cellulose digestion and digester apparatus for practicing said method
US3180789A (en) * 1962-07-18 1965-04-27 Hitachi Shipbuilding Eng Co Continuous pressurized impregnator type pulping digester

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3041232A (en) * 1957-02-06 1962-06-26 Kamyr Ab Method of continuous cellulose digestion and digester apparatus for practicing said method
US2996422A (en) * 1958-04-23 1961-08-15 Ed Jones Corp Digestion of cellulosic material
US3180789A (en) * 1962-07-18 1965-04-27 Hitachi Shipbuilding Eng Co Continuous pressurized impregnator type pulping digester

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5795438A (en) * 1996-11-04 1998-08-18 Ahlstrom Machinery Inc. Method and apparatus for feeding multiple digesters
US5985096A (en) * 1997-09-23 1999-11-16 Ahlstrom Machinery Inc. Vertical pulping digester having substantially constant diameter
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

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Publication number Publication date
SE302882B (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1968-08-05

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