EP0157279B1 - Pompage et traitement de sciure de bois - Google Patents

Pompage et traitement de sciure de bois Download PDF

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Publication number
EP0157279B1
EP0157279B1 EP85103154A EP85103154A EP0157279B1 EP 0157279 B1 EP0157279 B1 EP 0157279B1 EP 85103154 A EP85103154 A EP 85103154A EP 85103154 A EP85103154 A EP 85103154A EP 0157279 B1 EP0157279 B1 EP 0157279B1
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EP
European Patent Office
Prior art keywords
slurry
vessel
digester
sawdust
pump
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP85103154A
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German (de)
English (en)
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EP0157279A1 (fr
Inventor
Michael Ignacy Sherman
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Kamyr Inc
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Kamyr Inc
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Filing date
Publication date
Application filed by Kamyr Inc filed Critical Kamyr Inc
Publication of EP0157279A1 publication Critical patent/EP0157279A1/fr
Application granted granted Critical
Publication of EP0157279B1 publication Critical patent/EP0157279B1/fr
Expired 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
    • D21C7/00—Digesters
    • D21C7/06—Feeding devices

Definitions

  • US-A-3 586 600 teaches a digesting apparatus for handling sawdust wherein a thick stock pump is utilized to feed liquid mixed with the sawdust prior to pumping to an upflow impregnation vessel, through conventional horizontal steamer, and then downwardly into a pressurized cooking vessel.
  • sawdust may be treated in an upflow digester, or may be treated in a hydraulically filled downflow digester, or may be treated in a downflow digester having a superatmospheric vapor phase. This provides for greater thermal stability, which may be very desirable in many situations.
  • sawdust as used in the present specification and claims means sawdust and like cellulosic materials, including wood residues, which are fine enough to react like small particles during handling. This may be contrasted with the way that large comminuted cellulosic particles - such as wood chips - react during handling.
  • a key to the sawdust treatment process according to the present invention is the unexpected discovery that it is possible to pump sawdust slurries having a consistency high enough to effect practical chemical treatment thereof. That is, according to the present invention it has been found that it is possible to pump sawdust slurries having a solids consistency of between about 10-25%, and more desirably between about 15-22%.
  • Pumping can be accomplished utilizing commercially available fluidizing, high speed, degassing, centrifugal pumps and related systems such as shown in US-A-4 435 193 and 4 410 337, and sold commercially by Kamyr, Inc. of Glens Falls, New York, and Kamyr AB of Karlstad, Sweden, under the trademark MC @ pump.
  • sawdust is treated by: mixing the sawdust with a liquid to produce a slurry having a solids consistency of between about 10-25% (preferably about 15-22%); and pumping the slurry, without dilution, to a treatment stage to ultimately produce pulp.
  • the slurry is heated (either indirectly, or by direct mixing of high pressure steam with the slurry - as by utilizing a fluidizing mixer), the slurry is introduced into the vertical vessel, chemical treatment of the slurry within the vessel is practiced, and the slurry is discharged from the vessel.
  • the vessel is an upflow vessel and the slurry is pumped, without dilution, and under the influence of the fluidizing, high speed, centrifugal pump, up through the vessel.
  • the vessel may be a downflow vessel, either a hydraulically filled vessel or one having a superatmospheric vapor phase.
  • the chemical treatment in the vessel facilitates breaking down, or effects breaking down, of the lignin in the sawdust.
  • a sulfite treatment can be provided in the vessel, with the slurry discharged from the vessel then being passed to a refiner to produce a mechanical pulp.
  • the slurry may be subjected to Kraft processing in the vessel, resulting in the production of Kraft pulp.
  • the mixing of the sawdust with liquid is preferably practiced by mixing the sawdust with low pressure steam and a treatment liquid, and then feeding it into a vertical chute, and pumping the slurry from the bottom of the chute.
  • the slurry maintains substantially the same consistency (i.e. a consistency between about 10-25%) without phase separation (solid/liquid) throughout all the treatment procedures.
  • the apparatus comprises: a means for entraining the sawdust in a liquid; a fluidizing, high speed, centrifugal pump such as disclosed in US-A-4435 193 and 4410337; a vertical digester; a conduit between the pump and the digester; and a direct or indirect heating means for heating the slurry before introduction into the digester.
  • the interconnection between the pump and the digester consists of the conduit, a valve means in the conduit, and the heating means, the force provided by the pump ultimately effecting passage of the slurry through the digester.
  • FIGURE 1 illustrates a component for a preferred embodiment of an apparatus according to the present invention, for effecting the production of Kraft pulp.
  • the apparatus in this embodiment comprises a conventional low pressure feeder 10 mounted atop a conventional horizontal steaming vessel 12 (also known as a steam mixer, having a horizontal axis mixing screw therein), having a steam relief pressure controlled vent 14.
  • Sawdust is fed from a source to the feeder 10, and is introduced into the vessel 12 wherein it is entrained in liquid to produce a slurry.
  • the liquid may comprise white liquor from a Kraft process, and additionally low pressure steam is introduced into the vessel 12.
  • the slurry discharged from the vessel 12 is preferably discharged into a vertical chute 16, although it may instead be fed to a conduit connected directly to the pump to be hereinafter described.
  • a liquid level is maintained utilizing a conventional gamma level indicator 18, which controls a valve means 20 in a conduit 21 leading from the bottom of the chute 16.
  • a liquid, such as white liquor, is preferably introduced into the chute
  • the structures 10, 12, 14 and 16 comprise means for entraining the sawdust in liquid, to produce a slurry having a solids consistency of between about 10-25% (and preferably between about 15-22%).
  • the slurry has that consistency at the bottom of the chute 16, where the pump 22 is located.
  • the pump 22 is shown only schematically in FIGURE 1, but in addition to pumping components thereof it will have degassing components, as shown in US-A-4 435 193 and 4 410 337.
  • the pump 22 comprises a fluidizing, high speed, degassing, centrifugal pump. Typically, the impeller thereof is rotated at 2000-3400 rpm in order to effect fluidization of the slurry.
  • Such a pump 22 is commercially available from Kamyr, Inc. of Glens Falls, New York and Kamyr AB of Karlstad, Sweden, under the trademark MC @ pump.
  • the heating means 24 in the embodiment illustrated in FIGURE 1 comprises a mixer for directly mixing high pressure steam into the slurry.
  • Various forms such a mixer may take are shown in CA-A-1 102 604, such a mixer comprising a fluidizing mixer.
  • a typical mixer that may be utilized for the heating means 24 is sold by Kamyr, Inc. and Kamyr AB under the trademark MC @ mixer.
  • the vessel 26 comprises a continuous digester, and in the embodiment illustrated in FIGURE 1 is an upflow vessel having a conventional discharge mechanism 28 at the top thereof.
  • chemical treatment of the slurry may be practiced.
  • a Kraft delignification process is practiced in the vessel 26, white liquid - introduced during slurrying of the sawdust - providing an active alkali charge which conventionally will be in the range of 9-24% Na 2 0 on bone dry raw material.
  • the heating means 24 brings the slurry up to optimum cooking temperature normally in the range of 140-175°C.
  • the pump 22 brings the slurry up to normal treatment pressure, which is typically 600-1200 kPa, and the slurry is maintained at that pressure, and is maintained in the digester 26 for a time period of about 30-130 minutes.
  • normal treatment pressure typically 600-1200 kPa
  • These values are merely exemplary values, and they may vary somewhat depending upon the nature of the sawdust and the particular subsequent treatment steps to be applied to the pulp, and the ultimate pulp to be produced.
  • FIGURE 2 is substantially identical to that illustrated in FIGURE 1 except that heating of the slurry to optimum cooking temperature is accomplished utilizing an indirect heating means, and the digester 40 comprises a downflow digester.
  • the vertical vessel 30 connected to the pump 22 by the conduit 21 preferably comprises an indirect heating vessel with a movable screen, such as shown in US-A-4 368 628.
  • an indirect heating vessel with a movable screen the slurry is maintained, without dilution, at substantially the same pressure as it had when discharged from the pump 22.
  • Liquid is withdrawn from the vessel 30 by the pump 32, passes through steam heater 34, and is recirculated back to the vessel to be introduced at inlet 35.
  • the slurry is indirectly heated as it passes through the vessel 30 and the amount of liquid withdrawn at outlet 31 is substantially the same as the amount of liquid introduced at 35, so that the consistency of the slurry is not significantly changed during heating utilizing vessel 30.
  • the slurry is discharged from conventional discharge mechanism 36 and passes through conduit 37 to be introduced at the top 38 of the downflow digester 40. Pulp as it is produced is discharged from the bottom of the digester 40 utilizing a conventional discharge mechanism 42.
  • the downflow digester 40 will be hydraulically filled. Alternatively, it may have a superatmospheric vapor phase at the top thereof, and noncondensable gases may be vented - in this instance - utilizing vent 43. In either case, the thermal stability of the process is greatly enhanced compared to the substantially atmospheric digester utilized in commercial prior art practices.
  • the apparatus utilized in FIGURES 1 and 2 is primarily useful for the production of chemical pulp.
  • the apparatus of FIGURE 3 is utilized for the production of mechanical pulp, particularly chemimechanical pulp (CMP), or chemithermo- mechanical (CTMP) pulp.
  • CMP chemimechanical pulp
  • CTMP chemithermo- mechanical
  • the chemical treatment vessel 46 is much smaller than the vessels 26, 40, since complete delignification does not take place in the vessel.
  • sulfite is added to the slurry in the vessel 46 (for example by entraining the sawdust with sulfite in the mixing means), and the slurry when discharged from the vessel 46 in discharge line 47 passes to a conventional refiner 48.
  • the mechanical pulp produced is discharged into line 49.
  • sodium sulfite at pH 9-10 is the mild pretreatment liquid in the vessel 46, and the temperature therein is at about 130-170°C.
  • the temperature therein is at about 130-170°C.
  • no chemical need be added at all but rather merely by heating of the slurry with high pressure steam (as in fluidizing mixer 24) to about 110-150°C, fibrilization in refiner 48 will be facilitated, producing thermomechanical pulp (TMP).
  • sawdust is treated by mixing the sawdust with a liquid (in steam mixer 12 and chute 16) to produce a slurry having a solids consistency of between about 10-25%, and preferably between about 15-22%; and pumping the slurry, utilizing fluidizing, high speed, centrifugal pump 22, without dilution, to a treatment stage to ultimately produce pulp.
  • the slurry is heated to optimum temperature, and introduced into a treatment vessel. Heating may be accomplished directly - as by mixing high pressure steam directly into the slurry utilizing steam mixer 24- or indirectly, as by utilizing pressure diffuser 30.
  • the chemical treatment In the treatment vessel, some chemical treatment of the slurry is practiced.
  • the chemical treatment merely facilitates breaking down of the lignin in the sawdust where a mechanical pulp is ultimately to be produced. If a Kraft pulp is ultimately to be produced, in the vessel the chemical treatment breaks down the lignin in the sawdust.
  • the pulp is ultimately discharged from the vessel, whether it be vessel 26, 40 or 46.
  • the chemical treatment takes place during upflow, or hydraulically filled downflow.
  • Treatment in the vessel 46 may be a sulfite treatment, with the discharge pulp ultimately be refined in refiner 48.
  • Treatment in the vessels 26, 40 is a Kraft treatment, with the Kraft pulp ultimately being produced.

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  • Paper (AREA)

Claims (10)

1. Appareil destiné à produire de la pâte à partir de sciure de bois comprenant: des moyens pour entrainer (10,12,14,16) la sciure de bois dans un liquide pour produire une bouillie ou suspension pâteuse; une pompe (22); un lessiveur de pâte (26; 40; 46); une conduite (21) reliant entre eux la pompe et le lessiveur de pâte, la conduite comportant des moyens de vanne (20) disposés dans celle-ci; et des moyens (24, 30) disposés dans la conduite pour chauffer la bouillie pompée à partir de la pompe à destination du lessiveur de pâte; caractérisé en ce que: la pompe (22) comprend une pompe centrifuge fluidisante, de dégazage, à vitesse élevée, reliée de façon fonctionnelle aux moyens destinés à l'entrainement de la sciure de bois dans le liquide; et la pompe (22) est reliée par l'intermédiaire de la conduite (21) et les moyens de chauffage (24, 30) au lessiveur de pâte (26; 40; 46) de sorte que la pompe fournit la force motrice pour déplacer la bouillie à travers le lessiveur, et la liaison entre la pompe (22) et le lessiveur (26; 40; 46) est uniquement constituée par la conduite (21), les moyens de vanne (20) et de chauffage (24, 30).
2. Appareil selon la revendication 1, caractérisé en ce que le lessiveur est constitué par un lessiveur à courant ascendant (26, 46) comportant une entrée au fond de celui-ci et une évacuation (28) sur le dessus de celui-ci et dans lequel la conduite (21) et la pompe (22) sont reliées à l'entrée au fond du lessiveur.
3. Appareil selon la revendication 1, caractérisé en ce que le lessiveur (40) comprend un récipient à courant descendant rempli hydrauliquement, comportant une entrée sur le dessus de celui-ci et une évacuation (42) au fond de celui-ci, et dans lequel la conduite (21, 37) et la pompe (22) sont reliées à l'entrée (38) sur le dessus du lessiveur (40).
4. Appareil selon la revendication 1, caractérisé en ce que le lessiveur (46) comprend un lessiveur au sulfite, et dans lequel l'appareil comprend de plus un raffineur (48) relié de façon fonctionnelle à l'évacuation à partir du lessiveur (46).
5. Appareil selon la revendication 1, caractérisé en ce que les moyens destinés à entrainer la sciure de bois dans le liquide sont constitués par: un mélangeur de vapeur horizontal (12); un système d'alimentation basse pression (10) à travers lequel la sciure de bois est amenée au mélangeur de vapeur horizontal (12); des moyens pour introduire le liquide et la vapeur basse pression dans le mélangeur à vapeur horizontal (12); une goulotte s'étendant verticalement (16) et vers le bas depuis l'évacuation à partir du mélangeur de vapeur (12); et des moyens pour introduire le liquide dans la goulotte verticale (16); et caractérisé en ce que la pompe centrifuge fluidisante, de dégazage, à vitesse élevée, (22) est reliée fonctionnellement à une portion de fond de ladite goulotte (16).
6. Procédé destiné au traitement de la sciure de bois en mélangeant la sciure de bois avec un liquide pour produire une bouillie ayant un consistance en matières solides située entre environ 10 et 25%, caractérisé par les opérations consistant à:
-pomper de façon centrifuge la bouillie sans dilution importante jusqu'à une étape de traitement pour effectuer finalement la production de pâte;
-dégazer lors du pompage;
-chauffer la bouillie; et
- introduire la bouillie chauffée dans un récipient de traitement à la suite dudit pompage.
7. Procédé selon la revendication 6, caractérisé en ce que lors de l'étape de traitement, on effectue les opérations suivantes: (i) chauffage de la bouillie jusqu'à une température de traitement optimale; (ii) introduction de la bouillie chauffée dans un récipient de traitement continu à la suite du pompage; (iii) exécution du traitement chimique de la bouillie dans le récipient pour faciliter la décomposition ou pour effectuer la décomposition de la lignine dans la sciure de bois; et (iv) évacuer la bouillie traitée du récipient.
8. Procédé selon la revendication 7, caractérisé en ce que l'étape (ii) est réalisée en introduisant la bouillie dans le fond d'un récipient à courant ascendant, la bouillie s'écoulant vers le haut dans le récipient sous l'influence dudit pompage; et l'étape (iv) est réalisée en évacuant la bouillie traitée à partir du dessus du récipient; et l'étape (i) est réalisée en acheminant le liquide traité sous pression à l'intérieur du récipient de chauffage indirect; en évacuant du récipient un volume de liquide généralement proportionnel au volume du liquide chauffé introduit, et en chauffant le liquide évacué et en le recyclant pour fournir un liquide d'introduction chauffé; et l'étape (ii) est réalisée en faisant passer la bouillie chauffée en provenance de l'évacuation du récipient de chauffage indirect sur l'entrée du récipient de traitement.
9. Procédé selon la revendication 7, caractérisé en ce que le récipient est un récipient à courant descendant vertical, présentant une pression de vapeur maintenue sur le dessus, laquelle est sensiblement supérieure à la pression atmosphérique; et caractérisé en ce que l'étape (ii) est réalisée en amenant la bouillie directement sur le dessus du récipient sous l'influence du pompage, et l'étape (iv) est réalisée en évacuant à partir du fond du récipient.
10. Procédé selon la revendication 9, caractérisé en ce que l'étape (iii) est réalisée en effectuant un traitement au sulfite, et le procédé est caractérisé par l'étape (iv) consistant à faire passer la bouillie évacuée depuis le récipient à un stade de raffinage et d'effectuer le raffinage de la bouillie de sciure de bois pour produire une pâte mécanique.
EP85103154A 1984-04-02 1985-03-19 Pompage et traitement de sciure de bois Expired EP0157279B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US59611184A 1984-04-02 1984-04-02
US596111 1984-04-02

Publications (2)

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EP0157279A1 EP0157279A1 (fr) 1985-10-09
EP0157279B1 true EP0157279B1 (fr) 1988-08-10

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EP85103154A Expired EP0157279B1 (fr) 1984-04-02 1985-03-19 Pompage et traitement de sciure de bois

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EP (1) EP0157279B1 (fr)
JP (1) JPH0639755B2 (fr)
BR (1) BR8501512A (fr)
CA (1) CA1242055A (fr)
DE (1) DE3564300D1 (fr)
FI (1) FI78745C (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU2008307020B2 (en) * 2007-09-29 2011-10-20 China Aluminum International Engineering Corporation Limited A method and an apparatus for directly heating slurry

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FI79361B (fi) * 1988-01-05 1989-08-31 Ahlstroem Oy Foerfarande och apparatur foer underlaettande av uttoemning av fallroer eller liknande och behandling av massa i sagda utrymme.
US6325888B1 (en) 1995-08-31 2001-12-04 Andritz-Ahlstrom Inc. Method for pulping sawdust
US5753075A (en) * 1996-10-25 1998-05-19 Stromberg; C. Bertil Method and system for feeding comminuted fibrous material
US6106668A (en) * 1996-10-25 2000-08-22 Ahlstrom Machinery Inc. Method for feeding comminuted fibrous material
SE519555C2 (sv) * 2002-05-21 2003-03-11 Kvaerner Pulping Tech Metod för kontinuerlig kokning av vedrådvara till cellulosamassa
CA2455172C (fr) * 2003-01-30 2010-02-23 Andritz Inc. Alimentation de materiau fibreux hache fin au moyen de pompes centrifuges et a vis haute pression
SE532083C2 (sv) 2008-03-20 2009-10-20 Metso Fiber Karlstad Ab Matningssystem innefattande parallella pumpar för en kontinuerlig kokare
SE532060C2 (sv) 2008-03-20 2009-10-13 Metso Fiber Karlstad Ab Matningssystem innefattande parallella pumpar för en kontinuerlig kokare
US8888954B2 (en) 2008-03-20 2014-11-18 Valmet Ab Feeding system having pumps in parallel for a continuous digester

Citations (1)

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Publication number Priority date Publication date Assignee Title
US3001481A (en) * 1958-09-02 1961-09-26 Improved Machinery Inc Pump

Family Cites Families (8)

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Publication number Priority date Publication date Assignee Title
FR569326A (fr) * 1922-04-27 1924-04-10 Cuiseur continu sous pression
FR1226093A (fr) * 1958-06-04 1960-07-08 Buss Ag Procédé pour l'apport et l'enlèvement continu de substances solides dans un appareil se trouvant sous pression ou en dépression et dispositif pour la mise en oeuvre du procédé
US3475271A (en) * 1966-02-07 1969-10-28 Kamyr Ab Cellulose digester with washing apparatus
US3586600A (en) * 1967-07-27 1971-06-22 Improved Machinery Inc Continuous digesting apparatus
JPS489122U (fr) * 1971-06-11 1973-02-01
SE390990B (sv) * 1975-06-02 1977-01-31 Kamyr Ab Sett och anordning for impregnering av fibermaterial fore kokning medelst pulsering av tryck mellan kokartryck och ett legre tryck
US4410337A (en) * 1980-04-07 1983-10-18 A. Ahlstrom Osakeyhtio Method and an apparatus for separating a gas from a fibre suspension
US4370172A (en) * 1981-03-17 1983-01-25 Compagnie De Construction Mecanique Sulzer, French Societe Anonyme Controlled vortex pump feed for supplying cellulose-containing material to reaction vessel

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3001481A (en) * 1958-09-02 1961-09-26 Improved Machinery Inc Pump

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU2008307020B2 (en) * 2007-09-29 2011-10-20 China Aluminum International Engineering Corporation Limited A method and an apparatus for directly heating slurry

Also Published As

Publication number Publication date
JPH0639755B2 (ja) 1994-05-25
JPS60231890A (ja) 1985-11-18
FI78745B (fi) 1989-05-31
CA1242055A (fr) 1988-09-20
DE3564300D1 (en) 1988-09-15
FI851253L (fi) 1985-10-03
FI851253A0 (fi) 1985-03-28
FI78745C (fi) 1989-09-11
BR8501512A (pt) 1985-11-26
EP0157279A1 (fr) 1985-10-09

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