EP0471154A2 - Modifizierter und kontinuierlicher Sulfitaufschluss - Google Patents

Modifizierter und kontinuierlicher Sulfitaufschluss Download PDF

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Publication number
EP0471154A2
EP0471154A2 EP91108240A EP91108240A EP0471154A2 EP 0471154 A2 EP0471154 A2 EP 0471154A2 EP 91108240 A EP91108240 A EP 91108240A EP 91108240 A EP91108240 A EP 91108240A EP 0471154 A2 EP0471154 A2 EP 0471154A2
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EP
European Patent Office
Prior art keywords
vessel
sulfite
liquor
cooking liquor
sulfite cooking
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.)
Granted
Application number
EP91108240A
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English (en)
French (fr)
Other versions
EP0471154A3 (en
EP0471154B1 (de
Inventor
Bertil Stromberg
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.)
Kamyr Inc
Original Assignee
Kamyr Inc
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Filing date
Publication date
Application filed by Kamyr Inc filed Critical Kamyr Inc
Publication of EP0471154A2 publication Critical patent/EP0471154A2/de
Publication of EP0471154A3 publication Critical patent/EP0471154A3/en
Application granted granted Critical
Publication of EP0471154B1 publication Critical patent/EP0471154B1/de
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Classifications

    • 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
    • D21C3/00—Pulping cellulose-containing materials
    • D21C3/04—Pulping cellulose-containing materials with acids, acid salts or acid anhydrides
    • D21C3/06—Pulping cellulose-containing materials with acids, acid salts or acid anhydrides sulfur dioxide; sulfurous acid; bisulfites sulfites

Definitions

  • an improved continuous sulfite pulping process is practiced in which conventional sulfite cooking liquor is utilized, which liquor may be formed in a number of different ways and have a number of different compositions, but typically includes sulfur dioxide as the active ingredient, and also may include -- at one point or another -- calcium sulfite or bisulfite, magnesium sulfite or bisulfite, sodium sulfite or bisulfite, and/or ammonium sulfite or bisulifte.
  • the most common acid continuous sulfite pulping is typically in the pH range of 1.5-2.0, and a bisulfite pulping modification thereof is in the pH range of 4.5-5.0, with the highest temperature usually in the range of 140°-160°C.
  • various additives must be provided, such as anthraquinone (AQ), as is conventional.
  • a method and apparatus which overcome the problem associated with extraction screen plugging -- as set forth above -- and additionally have the totally unexpected effects of reducing the sulfite cooking chemical consumption by a significant amount (e.g. about 10%), and making the digester run better in general.
  • the temperature can be lowered by at least about 5°F compared to if the invention is not practiced. For example, if the typical cooking temperature for a continuous sulfite pulping process is 310-315°F, according to the invention the temperature is reduced to about 305°F.
  • the wash temperature is raised from about 250-280°F to about 300°F, however there is a net energy savings.
  • a method of producing cellulosic pulp by sulfite pulping, utilizing comminuted cellulosic fibrous material, and an upright digesting vessel having a top, bottom, and central portion comprises the steps of continuously: (a) Feeding comminuted cellulosic fibrous material entrained in sulfite cooking liquor into the top of the vessel under pressure. (b) Flowing the material and sulfite cooking liquor co-currently into the central portion of the vessel. (c) Introducing an effective amount of the sulfite cooking liquor utilized for producing pulp into the vessel adjacent the bottom thereof to flow countercurrently to the material moving downwardly in the vessel.
  • step (d) Extracting waste (red) liquor from the central portion of the vessel. And, (e) withdrawing sulfite pulp from the bottom of the vessel.
  • step (c) about 5-20% of the sulfite cooking liquor is introduced, e.g. about 10%.
  • the sulfite cooking liquor is introduced, here, preferably in a wash recirculation loop, prior to heating of the recirculated liquor, and the temperature at the wash zone may be maintained at least 5°F lower than it would conventionally be maintained for the same material, K-No. and other parameters if sulfite cooking without step (c) were practiced.
  • Steps (a)-(e) are preferably practiced to produce a pulp with a final K-No. preferably about 20 or below. However they are also practiced so that the K-No. at the withdrawal screens at the central portion of the digester is high enough, so that plugging of the screens does not occur (e.g. about 24 or above).
  • the waste liquor withdrawn from the central portion of the digester is flashed in flash tanks. Prior to introduction of the material and sulfite cooking liquor into the top of the digester, it is steamed, and introduced to a high pressure feeder. An impregnation vessel may optionally be utilized too.
  • apparatus for practicing sulfite pulping.
  • the apparatus comprises: An upright digesting vessel having a top, bottom, and central portion. Means for introducing material entrained in sulfite cooking liquor into the top of the vessel. Withdrawal screens at the central portion of the vessel for withdrawing waste liquor and feeding the waste to flash tanks or the like. An extraction screen located between the central portion of the vessel and the bottom thereof and operatively connected to an extraction loop, for withdrawing and recirculating liquor from the vessel so that the liquor passes upwardly in the vessel countercurrent to the flow of material downwardly in the vessel, to the central extraction screens.
  • This method modification may comprise the steps of: (a) Causing comminuted cellulosic fibrous material entrained in sulfite cooking liquor to flow in a first direction through a cooking zone. (b) Passing an effective amount of the sulfite cooking liquor countercurrent to the flow of material in the cooking zone. And, (c) withdrawing waste liquor from the cooking zone at the point where the countercurrent flow of sulfite cooking liquor terminates. Step (b) is preferably practiced with from 5% up to almost 100%, e.g. 20% or more, of the sulfite cooking liquor to be utilized.
  • the sulfite pulping is preferably acid or bisulfite pulping, and the reduction in consumption of cooking liquor is approximately 10%.
  • FIGURE 1 is a side schematic view showing an exemplary sulfite pulping apparatus according to the invention.
  • FIGURE 1 An exemplary system for sulfite pulping according to the invention is illustrated in FIGURE 1.
  • Entirely standard components include a chips bin 10 for receiving a feed of chips 11 or like cellulosic comminuted fibrous material. From the chips bin 10, the material goes to a horizontal steaming vessel 12, and a vertical conduit 13, sulfite cooking liquor being added to the material in the conduit 13 from source 14 to slurry the material as it is fed to high pressure feeder 15. From high pressure feeder 15 the material entrained in sulfite cooking liquor may pass to an optional impregnation vessel 16, and then in line 17 to the top 18 of a continuous digester 19.
  • the digester 19 At the top of the digester 19 there is a liquid/material separation device 20, which may comprise a screw within a cylinder, a plurality of bull screens with switching withdrawal from the screens, or the like. It is preferred that the digester 19 be a steam digester rather than hydraulic digester, although a functioning hydraulic digester can be constructed.
  • means for extracting waste liquor At the central portion 21 of the digester 19, approximately mid way between the top 18 and the bottom 22 thereof, means are provided for extracting waste liquor.
  • Such means include one or more screens 23 and a conduit 24 extending from the screens.
  • the waste liquor typically is flashed to form steam and more concentrated waste liquor by passing it to a series of flash tanks 25, as is conventional.
  • an extraction and recirculation loop 26 Between the central portion 21 and the top 18 of the digester there also is an extraction and recirculation loop 26, wherein some liquor is withdrawn through screens 27 under the influence of pump 28, passes through a heater 29 where it is indirectly heated with steam or the like, and then is returned to the interior of the digester as indicated at 30, preferably above the withdrawal point from screens 27.
  • the sulfite cooking liquor and the cellulosic material flow co-currently.
  • an outlet scraper 32 or the like At the bottom 22 of the digester 19 is an outlet scraper 32 or the like, and a discharge conduit 33 for sulfite pulp. Wash liquid from source 34 is added at 35 to the bottom 22. Also a wash circulation loop 36 is provided, including a screen 37, pump 38, and indirect heater 39, the recirculated liquid being returned to point 40 just above the screen 37.
  • the most significant aspect of the present invention is the introduction of an effective amount of sulfite cooking liquor from source 14 into the digester 19 to flow countercurrently to the material (chips) flow, as indicated by arrow 42. This is most easily accomplished by feeding sulfite cooking liquor from source 14 in line 44 so that it enters the wash circulation loop 36, just before pump 38 and heater 39.
  • the amount of sulfite cooking liquor added in line 44 will depend upon the particular material being handled, and other parameters, but normally is at least about 5% of the total amount of sulfite cooking liquor utilized for producing sulfite pulp. About 5 to 20% is a desirable range, with about 10% preferred.
  • sulfite cooking liquor is intended to encompass all conventional sulfite cooking liquors, whether for bisulfite pulping, acid sulfite pulping, neutral sulfite pulping, or alkaline sulfite pulping, and regardless of the exact chemical source of the active or inactive components.
  • the effect of adding the sulfite cooking liquor into the bottom portion of the digester 19 so that it flows countercurrently as indicated at 42 up to the screens 23, is to effectively extend the cooking time.
  • the cooking time may be three hours, but by the practice of the invention the same vessel 19 can be used in practicing a five hour cook.
  • the temperature in the cooking zone can be lowered, and thus an energy savings can be realized.
  • the temperature in the cooking zone between screens 23 and 27 was about 310-315°F. That temperature was reduced at least 5°F, e.g. an entirely workable temperature in the practice of the invention was 305°F in that zone.
  • the wash zone temperature was raised from the conventional level of about 250-280°F to about 300°F, since the downflow volume is larger than the upflow volume, and net energy savings ensues.
  • Another benefit from the practice of the invention is the solving of the problem of plugging of the extraction screens 23.
  • the K-No. at the extraction screens can be much larger than at the discharge, so that the chance of plugging is minimized.
  • a K-No. as low as 8 has been achieved according to the invention, which was never possible in conventional sulfite pulping using that same equipment.
  • the chance of plugging of the screens 23 is minimized since the K-No. at the screens 23 is about 24 or above (e.g. 30).
  • While the digester 19 illustrated in FIGURE 1 is the most feasible apparatus for the practice of the invention, and allows ready retrofitting of existing installations, according to the invention it is possible to produce sulfite pulp by running an entire vessel countercurrently. That is in an entire vessel the material may move downwardly while the sulfite cooking liquor moves upwardly, with extraction near the top of the vessel (that is at the end of the countercurrent flow of cooking liquor). In such a situation, from 5% up to close to 100% of the sulfite cooking liquor utilized can flow countercurrently, e.g. over about 20%.

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  • Polysaccharides And Polysaccharide Derivatives (AREA)
  • Paper (AREA)
  • Micro-Organisms Or Cultivation Processes Thereof (AREA)
  • Packages (AREA)
  • Materials For Medical Uses (AREA)
EP91108240A 1990-08-17 1991-05-22 Modifizierter und kontinuierlicher Sulfitaufschluss Expired - Lifetime EP0471154B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US56914290A 1990-08-17 1990-08-17
US569142 1990-08-17

Publications (3)

Publication Number Publication Date
EP0471154A2 true EP0471154A2 (de) 1992-02-19
EP0471154A3 EP0471154A3 (en) 1993-06-09
EP0471154B1 EP0471154B1 (de) 1997-11-26

Family

ID=24274268

Family Applications (1)

Application Number Title Priority Date Filing Date
EP91108240A Expired - Lifetime EP0471154B1 (de) 1990-08-17 1991-05-22 Modifizierter und kontinuierlicher Sulfitaufschluss

Country Status (10)

Country Link
EP (1) EP0471154B1 (de)
JP (1) JPH04240282A (de)
AT (1) ATE160601T1 (de)
AU (1) AU639109B2 (de)
BR (1) BR9103492A (de)
CA (1) CA2030090A1 (de)
DE (1) DE69128267T2 (de)
FI (1) FI913823A (de)
NO (1) NO913209L (de)
ZA (1) ZA909259B (de)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102009057208A1 (de) 2009-11-27 2011-06-01 Technische Universität Dresden Verfahren zur Herstellung von lignozellulosen Papierfaserstoffen sowie daraus gewonnene Papiere, Kartone und Pappen

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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
EP0407370A2 (de) * 1989-06-28 1991-01-09 Kamyr Ab Zellstoffkochen mit hoher Sulfidität, durch Sulfonierung von gedämpften Holzspänen mit Schwarzlauge

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FI44514B (de) * 1963-12-13 1971-08-02 Kamyr Ab
SE359331B (de) * 1970-03-17 1973-08-27 Kamyr Ab

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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
EP0407370A2 (de) * 1989-06-28 1991-01-09 Kamyr Ab Zellstoffkochen mit hoher Sulfidität, durch Sulfonierung von gedämpften Holzspänen mit Schwarzlauge

Also Published As

Publication number Publication date
FI913823A0 (fi) 1991-08-13
ZA909259B (en) 1991-11-27
NO913209L (no) 1992-02-18
AU639109B2 (en) 1993-07-15
NO913209D0 (no) 1991-08-16
DE69128267D1 (de) 1998-01-08
BR9103492A (pt) 1992-05-12
DE69128267T2 (de) 1998-06-18
JPH04240282A (ja) 1992-08-27
FI913823A (fi) 1992-02-18
EP0471154A3 (en) 1993-06-09
AU7829691A (en) 1992-02-20
ATE160601T1 (de) 1997-12-15
CA2030090A1 (en) 1992-02-18
EP0471154B1 (de) 1997-11-26

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