EP0502852B1 - Displacement heating in continuous digesters - Google Patents

Displacement heating in continuous digesters Download PDF

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Publication number
EP0502852B1
EP0502852B1 EP90914988A EP90914988A EP0502852B1 EP 0502852 B1 EP0502852 B1 EP 0502852B1 EP 90914988 A EP90914988 A EP 90914988A EP 90914988 A EP90914988 A EP 90914988A EP 0502852 B1 EP0502852 B1 EP 0502852B1
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EP
European Patent Office
Prior art keywords
liquor
chips
chamber
temperature
digester
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 - Lifetime
Application number
EP90914988A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0502852A1 (en
Inventor
Bertil K. E. Fagerlund
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.)
Beloit Technologies Inc
Original Assignee
Beloit Technologies Inc
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Filing date
Publication date
Application filed by Beloit Technologies Inc filed Critical Beloit Technologies Inc
Publication of EP0502852A1 publication Critical patent/EP0502852A1/en
Application granted granted Critical
Publication of EP0502852B1 publication Critical patent/EP0502852B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • D21C7/14—Means for circulating the lye
    • 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

Definitions

  • the present invention relates to improvements in apparatus and methods for the fiber liberating digestion of continuously fed comminuted cellulosic fiber material by cooking liquor and subsequent washing of the liberated fiber material. More particularly, the invention relates to an improved apparatus and process utilizing spent black liquor for heating the chips to effect savings in thermal energy, and for accomplishing high sulfidity cooking without changes to the overall sulfide balance of the system to accomplish a pulp having improved mechanical characteristics, to improve pulp yield, and to achieve extended delignification.
  • the first is batch cooking in which the chips are placed in a digester, liquor is added, the temperature and pressure are raised and the "batch" is maintained at the elevated temperature and pressure to reach the desired stage of delignification.
  • the digester is then emptied, and a subsequent fill is started for another batch.
  • a chip column continuously moves through the digester with hot liquor circulating therethrough. Process conditions are controlled such that the desired stage of delignification has occurred when the chips flow out of the digester.
  • the spent liquor is allowed to flash and steam is generated.
  • the steam is normally utilized to pre-steam the chips and to generate hot water.
  • the heat and cooking chemicals could be utilized more efficiently if the spent liquors were used to preheat and precondition the chips and to preheat the cooking chemicals such as white liquor in kraft processes which enters the process.
  • a further object of the invention is to provide a continuous digestion process wherein the used black cooking liquors and the white liquors are utilized in a unique manner in the process so as to obtain a saving in thermal energy, and to effect an improvement in the resultant qualities of the pulp which is produced.
  • Yet another object of the present invention is to provide a process for achieving high sulfidity cooking without significant changes to the overall sulfide balance of the cooking system, and for achieving extended delignification in a continuous digesting system while improving pulp yield over existing continuous digesting systems.
  • a feature of the invention is the provision of a continuous digestion process wherein a plurality of containers are used in sequence, with the first container receiving preconditioned chips and the chips being preimpregnated and heated in the first container with a low temperature black liquor. Further heating of the chips is accomplished with higher temperature liquors in the second and subsequent containers, and after the chips are brought up to the desired elevated temperature, a white liquor is circulated through the chips at the digestion temperature and pressure.
  • the chips are continuously fed from the last of the preimpregnation containers to the digester for cooking.
  • the cooked delignified chips are removed as pulp from the bottom of the digester and circulated to final washing.
  • the wash liquor from the washer is utilized in two or more stages to displace from the digester the free liquor and liquor within the chips.
  • the hot spent liquor is utilized to heat the incoming materials for the continuous digester.
  • the spent liquor having been extracted from the digester, is accumulated in pressure vessels substantially at digester temperature. Lower temperature liquors from final displacement stages are also accumulated.
  • the incoming chips are first exposed to the lower temperature liquors and then the higher temperature liquors.
  • the white liquor is preheated in a heat exchanger, utilizing a portion of hot spent liquor.
  • the white liquor can be stored in a hot white liquor accumulator whereas the hot spent liquor, after having given energy to the white liquor, goes to the low temperature accumulator.
  • the process can be accomplished wherein a first initial chamber or vessel is utilized, being fed by a screw conveyor feeder to press the chips downwardly.
  • the vessel may be employed with an extraction screen at the top and with a recirculation screen further down the vessel, with the recycled liquor flowing through a central pipe ending at the screen level.
  • Low temperature liquor is fed from a low temperature tank to a circulation pump, and the liquor is evenly spread over the vessel area.
  • the amount of liquor extracted from the top screen is an amount that generally corresponds to the white liquor charge, wood moisture and the dilution factor.
  • the extracted liquor goes to the evaporators.
  • the remaining part of the liquor goes with the chips downwardly in the chamber.
  • the treatment with hot spent liquor takes place in a vessel at principally digester pressure.
  • this high pressure vessel is located underneath the first vessel, and the transfer of material takes place in utilizing a high pressure feeder.
  • the arrangement for heat exchange is, in principal, essentially the same as in the first lower temperature vessel.
  • the hot spent liquor is introduced in a recirculation circuit, and a portion of the liquor flows countercurrent to the chips, being extracted from a top screen.
  • the low temperature liquor is being displaced and substituted by a hot spent liquor.
  • the low temperature liquor which leaves the top screen is conveyed back to the low temperature tank.
  • a portion of the hot spent liquor is utilized to preheat the white liquor that is introduced in the bottom of the high pressure vessel.
  • white liquor should be added after that mechanical device to avoid pulp deterioration. This can be done by utilizing a vessel which forms part of the continuous digester and is integrated into the digester apparatus itself.
  • Figure 1 is a schematic drawing of a process for operating in accordance with the principles of the present invention.
  • Figure 2 is a schematic drawing of a modification of the process shown in Figure 1, wherein the high pressure preimpregnation vessel forms a part of the continuous digester.
  • wood chips are delivered to a first chamber or container 10 through a screw delivery mechanism 11.
  • the chips may be preconditioned, such as by being heated by steam, in a supply container 12.
  • the preheating occurs by a supply of low temperature black liquor supplied from a low temperature black liquor tank 13 through a supply line 14.
  • the black liquor is circulated through the chips through a recirculating mechanism including a recirculating line 15 and a recirculating pump 16.
  • preheated wood chips are forcibly conveyed downwardly to a second container 21, which is a hot liquor preimpregnator in which the wood chips are subjected to liquor for a predetermined time at a higher temperature and high pressure than in the first container.
  • a mechanism such as a rotary delivery valve 20 is employed.
  • Such valves are well-known to those skilled in the art and will not be described further herein.
  • hot black liquor is delivered to the second container by line 23, which receives hot black liquor from a hot black liquor tank 22 delivered by a pressure pump 22a.
  • the hot black liquor is recirculated through the moving chips by recirculation line 24, with the liquor being circulated by a pump 24a.
  • a portion of the liquor is removed through a line 24b, controlled by a valve 24c, to be delivered back to the low temperature black liquor tank 13, preferably upstream of a delivery pump 13a which pumps the low temperature black liquor to the first container 10.
  • screens 21a, 21b, and 21c Arranged in the second container 21 are screens 21a, 21b, and 21c, which allow for the removal of the liquor, with the screen 21a facilitating the removal of the excess black liquor through the line 24b, and the screens 21b and 21c facilitating the recirculation of the high temperature black liquor in two recirculation paths.
  • white liquor is delivered to the second container 21 through a line 25.
  • the white liquor can be supplied through a line 25a, shown by dotted line in Figure 1, as the chips leave the second container.
  • the white liquor is obtained from a high temperature white liquor tank 27, being delivered therefrom by a pump 27a.
  • the white liquor is preheated before delivery to the second container 21 in a heat exchanger 28, with the white liquor being supplied to the heat exchanger from a supply source not shown and a supply line 29.
  • the heat exchanger is heated by hot black liquor supplied through a line 30 leading from the high temperature black liquor tank 22, and, after passing through the heat exchanger, the black liquor flows through a line 31 to the low temperature black liquor tank 13.
  • Cooking liquor is recirculated at the top of the digester through a circuit 34 having a recirculation pump 34a and extraction screen 34b therein. Temperature adjustment of the cooking liquor may be achieved with a trim heat exchanger 34c heated by steam from a steam source 34d.
  • a portion of the cooking liquor is removed from the digester through a line 38 by a pump 38a, and is delivered through a line 39 to the location where the chips exit the second container. This recirculated cooking liquor further dilutes the chips and liquor exiting the second container to facilitate transport of the chips to the digester.
  • the chips move continuously downward, and are cooked to the desired level of delignification.
  • Recirculation takes place through an extraction line 35, an extraction screen 35a, a recirculation line 36, and a pump 36a.
  • a portion of the recirculated liquor is directed to the hot liquor tank 22, controlled by a valve 36b.
  • washer filtrate from a line 50 is recirculated through a circuit 52 by a pump 54, to eliminate temperature and spent liquor concentration gradients.
  • the filtrate is added between an extraction screen 56 and the pump 54, so that the extracted liquor volume is less than the flow into the digester through circuit 52, causing an upward flow of filtrate in the bottom of the digester.
  • a second recirculation circuit 60 including a pump 62, is provided to extract a portion of the upward flowing filtrate at an extraction screen 64, together with remaining hot spent black liquor.
  • a portion of the extracted filtrate and liquor is directed to the low temperature tank 13, through line 66 controlled by a valve 68.
  • a blow line 80 is provided for removing pulp from the digester to a washer.
  • the manner in which the pulp is moved from the digester, including any secondary dilution, is well-known in the art of continuous digesters and will not be described further herein.
  • preconditioned pulp is delivered via a screw conveyor 11 into a first chip preheating container 10 where it is heated by low temperature black liquor obtained from a low temperature black liquor tank 13.
  • the preheated chips pass downwardly through a rotary delivery valve 20 to a second chamber 21, where the chips are further preheated by high temperature black liquor received from a high temperature black liquor tank 22.
  • the high temperature and low temperature black liquors are obtained from the pulp washer with the high temperature liquor also being utilized for heating the white liquor through the heat exchanger 28.
  • White liquor delivered through the screen 21c from a white liquor supply line 25, is added to the chips before the chips enter digester 33.
  • the region of the countercurrent flow between screen 64 and screen 35a should be sufficiently long that the filtrate is heated by the chips substantially to cooking temperature, and the liquor and filtrate removed through line 35a are at or near cooking temperature.
  • Figure 2 illustrates, in schematic format, a process in which the second chamber 21 is continguous with the digester. Corresponding parts of the process depicted in Figure 2 have been numbered similarly to Figure 1.
  • the various extraction screens, recirculation circuits, pumps, and the like for both the high pressure preimpregnation process and the final digestion process are contained in the combined preimpregnation and digester vessel.

Landscapes

  • Paper (AREA)
  • Chemical And Physical Treatments For Wood And The Like (AREA)
EP90914988A 1989-09-28 1990-09-25 Displacement heating in continuous digesters Expired - Lifetime EP0502852B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US41392089A 1989-09-28 1989-09-28
US413920 1989-09-28

Publications (2)

Publication Number Publication Date
EP0502852A1 EP0502852A1 (en) 1992-09-16
EP0502852B1 true EP0502852B1 (en) 1993-11-03

Family

ID=23639200

Family Applications (1)

Application Number Title Priority Date Filing Date
EP90914988A Expired - Lifetime EP0502852B1 (en) 1989-09-28 1990-09-25 Displacement heating in continuous digesters

Country Status (10)

Country Link
EP (1) EP0502852B1 (zh)
JP (1) JPH0674557B2 (zh)
KR (1) KR0171423B1 (zh)
CN (1) CN1021980C (zh)
CA (1) CA2066181C (zh)
DE (1) DE69004438T2 (zh)
ES (1) ES2045948T3 (zh)
FI (1) FI921373A (zh)
NO (1) NO179016C (zh)
WO (1) WO1991005103A2 (zh)

Families Citing this family (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE69111165T2 (de) * 1990-09-20 1995-11-16 Kvaerner Pulping Tech Tränkung mit Schwarzlauge vor der Zufuhr der Weisslauge.
US5302247A (en) * 1992-11-02 1994-04-12 Kamyr, Inc. Top circulation line cooling for a modified cook digester
CN1071997C (zh) * 1993-06-18 2001-10-03 叶隆清 植物促长剂及制造方法
US5824187A (en) * 1993-12-29 1998-10-20 Kvaerner Pulping Ab Method for the continuous cooking of pulp
SE502039C2 (sv) * 1993-12-29 1995-07-24 Kvaerner Pulping Tech Sätt och anordning för kontinuerlig kokning av massa
US6248208B1 (en) 1995-06-02 2001-06-19 Andritz-Ahlstrom Inc. Pretreatment of chips before cooking
AT403301B (de) 1996-04-04 1998-01-26 Impco Voest Alpine Pulp Tech Kontinuierliche flüssigkeitsführung
US6159336A (en) * 1997-08-07 2000-12-12 Kvaerner Pulping Ab Method and device for the continuous cooking of pulp
SE0104272L (sv) 2001-12-17 2002-11-12 Kvaerner Pulping Tech Förfarande och arrangemang vid impregnering av flis
SE518957C2 (sv) * 2002-01-24 2002-12-10 Kvaerner Pulping Tech Förfarande för att öka värmeekonomin i kokarsystemet vid kontinuerlig kokning
SE527058C2 (sv) * 2004-02-09 2005-12-13 Kvaerner Pulping Tech Kontinuerlig kokprocess med förbättrad värmeekonomi
US9567360B2 (en) * 2010-07-07 2017-02-14 Stora Enso Oyj Process for production of precipitated lignin from black liquor and precipitated lignin produced by the process
CN101906730B (zh) * 2010-07-15 2013-01-23 轻工业杭州机电设计研究院 非木纤维连续蒸煮方法及其装置
CN102154398A (zh) * 2010-12-28 2011-08-17 国润金华（北京）国际能源投资有限公司佛山高明分公司 一种高温高压纤维素转糖工艺
CN103597139B (zh) * 2011-03-25 2016-03-30 S·L·凯斯瓦尼 用于自横管式连续蒸煮器提取黑液的方法和系统
CN102154874B (zh) * 2011-04-29 2012-11-21 白福安 一种置换蒸煮制浆方法
CN102797189A (zh) * 2012-08-11 2012-11-28 李肥生 两段式自加热螺旋结构蒸煮分离器
US9644317B2 (en) * 2014-11-26 2017-05-09 International Paper Company Continuous digester and feeding system
FR3039567A1 (fr) * 2015-07-31 2017-02-03 Commissariat Energie Atomique Dispositif et procede de traitement de la liqueur noire provenant de la preparation de pate a papier par liquefaction hydrothermale
CN108385430A (zh) * 2016-12-20 2018-08-10 常州爱上学教育科技有限公司 强度较高的木、竹原料制成的浆料
KR102295018B1 (ko) 2019-09-11 2021-08-30 한병엽 포장용기 자동 주문발주 장치
KR102490233B1 (ko) 2020-11-24 2023-01-18 한병엽 포스 장치, 포스 장치의 주문 정보 처리방법, 기록매체

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FI63610C (fi) * 1981-12-31 1983-07-11 Ekono Oy Foerfarande foer kontinuerlig uppslutning av finfoerdelat material
SE452482B (sv) * 1982-04-28 1987-11-30 Sunds Defibrator Forfarande for satsvis framstellning av sulfatmassa med hog delignifieringsgrad
JPS6059189A (ja) * 1983-08-24 1985-04-05 ベロイト　コ−ポレ−ション 多段式木材チツプ蒸解法
FI71176C (fi) * 1983-11-30 1991-12-03 Ekono Oy Foerfarande foer framstaellning av cellulosa med satsvis kokning.

Also Published As

Publication number Publication date
NO920630D0 (no) 1992-02-18
WO1991005103A3 (en) 1991-05-16
KR0171423B1 (ko) 1999-05-01
FI921373A0 (fi) 1992-03-27
KR920703920A (ko) 1992-12-18
NO920630L (no) 1992-02-18
NO179016B (no) 1996-04-09
NO179016C (no) 1996-07-17
CN1050579A (zh) 1991-04-10
DE69004438T2 (de) 1994-05-11
WO1991005103A2 (en) 1991-04-18
CA2066181C (en) 1995-09-26
CA2066181A1 (en) 1991-03-29
JPH0674557B2 (ja) 1994-09-21
FI921373A (fi) 1992-03-27
DE69004438D1 (de) 1993-12-09
CN1021980C (zh) 1993-09-01
JPH05503739A (ja) 1993-06-17
ES2045948T3 (es) 1994-01-16
EP0502852A1 (en) 1992-09-16

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