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WO1999066122A1 - Machine a secher la pate a papier et technique correspondante - Google Patents

Machine a secher la pate a papier et technique correspondante Download PDF

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Publication number
WO1999066122A1
WO1999066122A1 PCT/FI1999/000490 FI9900490W WO9966122A1 WO 1999066122 A1 WO1999066122 A1 WO 1999066122A1 FI 9900490 W FI9900490 W FI 9900490W WO 9966122 A1 WO9966122 A1 WO 9966122A1
Authority
WO
WIPO (PCT)
Prior art keywords
pulp
long
wire
nip
roll
Prior art date
Application number
PCT/FI1999/000490
Other languages
English (en)
Inventor
Jorma Koskinen
Leo LUNDÉN
Original Assignee
Valmet Corporation
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Valmet Corporation filed Critical Valmet Corporation
Priority to AU46206/99A priority Critical patent/AU4620699A/en
Publication of WO1999066122A1 publication Critical patent/WO1999066122A1/fr

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Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F3/00—Press section of machines for making continuous webs of paper
    • D21F3/02—Wet presses
    • D21F3/04—Arrangements thereof
    • D21F3/045—Arrangements thereof including at least one extended press nip
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F3/00—Press section of machines for making continuous webs of paper
    • D21F3/02—Wet presses
    • D21F3/04—Arrangements thereof
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F9/00—Complete machines for making continuous webs of paper
    • D21F9/02—Complete machines for making continuous webs of paper of the Fourdrinier type

Definitions

  • the present invention relates to an apparatus for drying pulp, said apparatus comprising at least a wire section, which receives the pulp to be dried from a head box, as well as a press assembly, comprising at least one press nip, the wire section's wet wire being adapted to pass therethrough.
  • the invention relates also to a method for increasing the dry content of pulp by means of a pulp-drying machine, said drying machine comprising at least a wire section and a press section, by which method the dry content of pulp is increased through dewatering in the wire section at least to about 13-20%, the dry content being subsequently increased further by pressing the web.
  • pulp i.e. a chemical stock, e.g. for reinforcing a web or providing it with desired qualities.
  • Pulp is typically mixed in with e.g. a stock matter in a given desired amount.
  • pulp is only used in paper making for a part of the entire amount of paper to be produced.
  • the pulp can be received along pipelines from a pulp mill connected to the actual paper mill.
  • a large portion of the produced pulp is used in paper mills far away from the pulp mill itself, i.e. the pulp is manufactured as so- called market pulp.
  • Fig. 1 depicts schematically one prior art basic type for the wet end of pulp- drying machines, comprising a fourd nier-wire forming section 2, wherein the stock to be delivered by means of a head box 1 onto a fourdrinier wire 7 is first subjected to dewatering, the dry content following the wire section being typically about 20%.
  • a web W is carried to a press section, which includes e.g. a so-called combi-press, wherein the web travels in a supported manner through two press nips N2-N3.
  • a press section which includes e.g. a so-called combi-press, wherein the web travels in a supported manner through two press nips N2-N3.
  • the wire section can be provided with a separate nip N1 , a so-called lump breaker, whose main purpose is to break up pulp lumps which are formed too early and/or are excessively large, as suggested even by its name.
  • a lump breaker, rolls 3, 16, is provided with normal press rolls.
  • the lump breaker is linked with the top felt run of a combi-press, which is not necessary.
  • the web is sufficiently dry (dry content more than about 40%) and, thus, durable to be advanced to a fourth press/separate press, e.g. to a SymBeltTM-shoe press, rolls 18, 19, from whose press nip N4 the web is carried further to evaporation drying at a dry content of about 50%.
  • this type of wet end in a pulp-drying machine involves a number of problems.
  • One drawback can be said to be a large number of rolls in the combi- press.
  • rolls 4, 15, 17, the combi-press requires a plurality of guide rolls for a felt 5, 8, as well as felt conditioners.
  • the combi-press includes a centre roll 15 which is a suction roll, which means high investment costs.
  • the lump breaker used in this mechanism is highly sensitive in terms of the adjustment of a nip pressure. If the line pressure is increased too much, the web becomes useless, in other words, its fabric structure breaks up and carrying the web forward in the machine becomes impossible.
  • an object of the invention is to introduce a pulp-drying method intended for minimizing the above drawbacks.
  • the principal objective of a drying machine used for drying pulp is to bring the pulp to a desired dryness as cost-efficiently as possible, and it must be remembered that the material to be dried is pulp rather than a mixture of various fiber materials and additives (possibly just one component being pulp), which is the case in paper making. This involves e.g. the fact that mechanical dewatering of the stock should be as effective as possible, yet such that the actual pulp fibers do not suffer.
  • Differences between pulp drying and paper making include e.g. substantially different quadratic weights, which in the case of pulp are in the order of 600- 1000 g/m 2 , while cardboard has a maximum quadratic weight of about 550 g/m 2 and for paper it is maxiamally about 150 g/m 2 .
  • the speed of a pulp- drying machine is typically less than 200 m/min, while the speeds of a paper making machine can be in the order of more than 1600 m/min.
  • the stock emerging from the head box has a temperature which in old machines is at least 55°C and in new ones typically more than 60°C, preferably about 70°C, while in paper making machines the respective temperatures are typically less than about 45°C.
  • paper board is always an end product which must meet requirements that are totally different from those set on dried pulp, which is a raw material.
  • the requirements set on dried pulp concern primarily its handling during a drying process, requirements set by the handling of dried pulp, shipping, and pulping in a paper mill.
  • the purpose of a pulp-drying machine is not to significantly influence the qualities of a pulp sheet itself.
  • the process is determined by qualities that the end product must have, such as smoothness, gloss, opacity, printing quality, etc.
  • an apparatus of the invention for drying pulp comprising at least a wire section, which receives the pulp to be dried from a head box, as well as a press assembly, comprising at least one press nip, the fourdrinier wire section's wet wire being adapted to run therethrough, is principally characterized in that the wire section's wet wire is adapted to travel through a nip of at least one long-nip press, and that the long-nip press is provided with means for two-way dewatering.
  • a method of the invention for increasing the dry content of pulp by means of a pulp-drying machine, said drying machine comprising at least a wire section and a press section, by which method the dry content of pulp is increased through dewatering in the wire section at least to about 15-20%, the dry content of a pulp web being subsequently increased further by pressing the pulp web, is principally characterized in that the dry content of pulp is increased after dewatering in the wire section by delivering the pulp web together with at least the wire section's wire through a pressing element, in which pressing element the dry content of the pulp web is increased to a value of more than about 40%, whereafter the pulp web is carried forward from the wire section to a next stage of increasing the dry content.
  • a wire section of the invention for a pulp-drying machine comprising at least a bottom wire loop, above which a pulp stock can be delivered for dewatering the stock, is principally characterized in that the bottom wire loop is adapted to travel through a long-nip press, constituted by a long-nip roll external of the wire loop and a counter-roll internal of the wire loop, together with a felt adapted to run around the long-nip roll, the dewatering of a pulp web being adapted to occur in said long-nip press in two directions.
  • a method of the invention for increasing the dry content of pulp by means of a pulp-drying machine, the dry content of pulp being increased by said method through dewatering in a wire section, which is adapted to occur preferably at least partially in two directions, at least to about 15-20%, is principally characterized in that, after dewatering in the wire section, the dry content of pulp is increased by guiding the pulp web, together with the wire section's wet wire and an overhead felt, through a first long-nip press for dewatering the pulp web in two directions, in which long-nip press the dry content of pulp is increased in one nip to a value of more than about 40%, whereafter the pulp web is delivered even through a second long-nip press between the felts for dewatering the pulp web in two directions, in which second long-nip press the dry content of pulp is increased to a value which is preferably more than about 55%.
  • fig. 1 shows one press assembly according to the prior art
  • fig. 2 shows a press assembly of the invention in one preferred embodiment
  • fig. 3 shows a press assembly of the invention in another preferred embodiment
  • fig. 4 shows a third solution of the invention.
  • the pulp-drying machine shown schematically in fig. 1 includes a head box 1 for supplying stock onto a fourdrinier wire included in a fourdrinier wire section 2, said wire 7 running around a reversing roll 3 at the downstream end of the wire section, and around a drawing roll 4 as well as a number of guide rolls.
  • the fourdrinier wire section 2 includes typically e.g. foil strips, foil vacuum boxes, and suction boxes, not shown in the figure and used for eliminating water from a stock carried on top of the fourdrinier wire, such that the pulp web will have a dry content of about 13-20% downstream of the fourdrinier wire section.
  • a web W is delivered to a first press nip N1 of a combi-press, which is a so-called lump breaker, described earlier and constituted by rolls 3 and 16, and thence further to nips N2 and N3, whose centre roll comprises a suction roll 15 and counter-rolls comprise e.g. smooth rolls 4 and 17, respectively.
  • a top felt 5 and around the roll 17 and various guide rolls a bottom felt 8.
  • the web W is carried to a nip N4 constituted by rolls 18 and 19, around which runs a top felt 6 and, respectively, a bottom felt 9.
  • the web is carried to evaporation drying. Downstream of the nip N4 the web has a dry content which is typically about 50%, and in presently available machines the maximum dry content is about 53%.
  • the combi- press of fig. 1 constituted by two nips N2-N3 has been replaced with a long-nip press, comprising a long-nip roll 10 external of the wire 7 and a drawing roll 4 internal of the wire, with a long nip PN1 formed therebetween.
  • the length of such a long nip is selected such that the dwell time of a pulp web is preferably more than 40 ms, more preferably more than 50 ms. It can be roughly said that, in a solution of the invention, the dwell time is about quintuple with respect to the dwell time achieved by a combi-press.
  • the pulp web is typically very thick and, thus, a long active press time of the invention is particularly beneficial, especially at a dry content suggested by the invention, i.e. by the time the fabric of a pulp web is already sufficiently bonded, yet the web contains plenty of water to be pressed out.
  • the dry content of the pulp web W can be increased with a single nip press from a value of about 20% downstream of the fourdrinier wire to a value of more than about 40%, which matches the dry content of a pulp web downstream of the prior art combi-press of fig. 1 after two separate nips N2-N3.
  • the pulp web is drawn into a further nip press constituted by rolls 11 and 12, the bottom roll 11 of which is preferably a long nip roll, said web W running through two consecutive long nips PN1 and PN2 prior to being guided to a drying apparatus 14.
  • the web has a dry content which is more than about 50%, preferably more than about 55%, and most preferably more than about 60%.
  • the embodiment of fig. 3 differs from that of fig. 2 in that the wire section has its wire 7 adapted to run around a reversing roll 3 and a drawing roll 4 as in the prior art solution of fig. 1 , the first long nip PN1 being formed between a long nip roll 10 and the reversing roll 3.
  • the overhead felt loops 5 and 6 depicted in the solution of fig. 2 are in fig. 3 combined as a single felt loop 13, extending around the long nip roll 10 of the first long nip and a counter-roll 12 of the second long nip, as well as around necessary guide rolls.
  • the pulp stock is delivered from a head box 1 onto a wire section 2 into a narrowing space between two wire loops, wherein the increase of a dry content in the pulp web occurs essentially immediately in two directions.
  • the area constituted by two wires is preferably provided with a so-called lump breaker N1 ⁇ and then the bottom wire is provided with a fourdrinier vacuum box assembly. Thereafter, the pulp web, supported by the bottom wire, is carried according to the invention along with at least the wire section's wet wire through a long nip press PN1.
  • the solution of fig. 4 can be used e.g. for reducing substantially the machine length, whereby, for example in connection with machine renovations, it will be possible to increase the size of an evaporation drying cabinet in view of increasing production over the entire line.
  • a smooth counter-roll it is conceivable to use, e.g. a suction roll, a grooved roll or a through-drilled jacketed roll as a counter-roll of the long-nip press.
  • a through-drilled jacketed roll is used as a counter-roll the area of the bores of the through-drilled roll is preferably at least about 20 % of the total area of the roll's jacket in order to achieve sufficient open area for a pulp-drying machine's dewatering capability.

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  • Paper (AREA)

Abstract

Cette invention a trait à une machine à sécher le papier et à la technique correspondante. Cette machine comporte au moins une section table de fabrication (2), recevant la pâte à sécher en provenance d'une caisse supérieure (1) ou analogue, ainsi qu'un ensemble presse comprenant au moins une pince, la table de fabrication humide de la section table de fabrication étant conçue pour traverser cette pince. Dans le cas de l'appareil de l'invention, la section table de fabrication comporte une table humide (7) conçue pour passer par une pince (PN1) d'au moins une presse à longue pince, celle-ci étant dotée de dispositifs (5, 7) exécutant un égouttage à double sens de la bande de pâte. Dans le cadre de la technique de l'invention, le taux de séchage de la pâte est accru après égouttage de la section de table de fabrication du fait du passage de la bande de pâte avec au moins la table humide (7) de la section table de fabrication par un élément de pressage dans lequel le taux de séchage de la bande de pâte augmente de plus de 40 % environ. Après cette opération, la bande de pâte quitte la section table de fabrication pour être dirigée sur une nouvelle opération destinée à accroître le taux de séchage.
PCT/FI1999/000490 1998-06-16 1999-06-07 Machine a secher la pate a papier et technique correspondante WO1999066122A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU46206/99A AU4620699A (en) 1998-06-16 1999-06-07 Apparatus and method for drying pulp

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI981391 1998-06-16
FI981391A FI109815B (fi) 1998-06-16 1998-06-16 Laitteisto ja menetelmä selluloosan kuivaamiseksi

Publications (1)

Publication Number Publication Date
WO1999066122A1 true WO1999066122A1 (fr) 1999-12-23

Family

ID=8552006

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/FI1999/000490 WO1999066122A1 (fr) 1998-06-16 1999-06-07 Machine a secher la pate a papier et technique correspondante

Country Status (3)

Country Link
AU (1) AU4620699A (fr)
FI (1) FI109815B (fr)
WO (1) WO1999066122A1 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001036746A1 (fr) * 1999-11-17 2001-05-25 Andritz Ag Dispositif d'assechement pour bande de matiere fibreuse
DE10137527A1 (de) * 2001-08-01 2003-02-13 Voith Paper Patent Gmbh Pressenanordnung
WO2012054944A1 (fr) 2010-10-27 2012-05-03 Andritz Ag Dispositif et procédé de séchage de matière fibreuse
WO2020211991A1 (fr) * 2019-04-18 2020-10-22 Andritz Ag Dispositif et procédé de transfert d'une section d'une bande
FI131301B1 (fi) * 2022-12-09 2025-01-30 Valmet Technologies Oy Puristinjärjestely sellunkuivauskoneella ja sellunkuivauskoneen märkäpää

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE29623297U1 (de) * 1996-12-23 1998-03-05 Voith Sulzer Papiermaschinen GmbH, 89522 Heidenheim Naßpresse

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE29623297U1 (de) * 1996-12-23 1998-03-05 Voith Sulzer Papiermaschinen GmbH, 89522 Heidenheim Naßpresse

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001036746A1 (fr) * 1999-11-17 2001-05-25 Andritz Ag Dispositif d'assechement pour bande de matiere fibreuse
US6616810B1 (en) * 1999-11-17 2003-09-09 Andritz Ag Device for removing water from a fibrous material strip
DE10083529B4 (de) * 1999-11-17 2007-03-08 Andritz Ag Vorrichtung zur Entwässerung einer Faserstoffbahn
DE10137527A1 (de) * 2001-08-01 2003-02-13 Voith Paper Patent Gmbh Pressenanordnung
WO2012054944A1 (fr) 2010-10-27 2012-05-03 Andritz Ag Dispositif et procédé de séchage de matière fibreuse
CN103189566A (zh) * 2010-10-27 2013-07-03 安德里茨股份有限公司 用于干燥纤维材料的装置和方法
JP2013540912A (ja) * 2010-10-27 2013-11-07 アンリツ アクティエンゲゼルシャフト 乾燥繊維質材料を乾燥するための装置及び方法
CN103189566B (zh) * 2010-10-27 2015-09-16 安德里茨股份有限公司 用于干燥纤维材料的装置和方法
US9506692B2 (en) 2010-10-27 2016-11-29 Andritz Ag Device and method for drying fibrous material
WO2020211991A1 (fr) * 2019-04-18 2020-10-22 Andritz Ag Dispositif et procédé de transfert d'une section d'une bande
US11946203B2 (en) 2019-04-18 2024-04-02 Andritz Ag Device and method for transferring a strip of a web
FI131301B1 (fi) * 2022-12-09 2025-01-30 Valmet Technologies Oy Puristinjärjestely sellunkuivauskoneella ja sellunkuivauskoneen märkäpää

Also Published As

Publication number Publication date
AU4620699A (en) 2000-01-05
FI981391A7 (fi) 1999-12-17
FI981391A0 (fi) 1998-06-16
FI109815B (fi) 2002-10-15

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