US20040144513A1 - Method and process arrangement in the short circulation of a paper machine - Google Patents

Method and process arrangement in the short circulation of a paper machine Download PDF

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Publication number
US20040144513A1
US20040144513A1 US10/475,504 US47550404A US2004144513A1 US 20040144513 A1 US20040144513 A1 US 20040144513A1 US 47550404 A US47550404 A US 47550404A US 2004144513 A1 US2004144513 A1 US 2004144513A1
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US
United States
Prior art keywords
stock
headbox
flow
fan pump
dilution
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.)
Abandoned
Application number
US10/475,504
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English (en)
Inventor
Matti Hietaniemi
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.)
Valmet Technologies Oy
Original Assignee
Metso Paper Oy
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 Metso Paper Oy filed Critical Metso Paper Oy
Assigned to METSO PAPER, INC. reassignment METSO PAPER, INC. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: HIETANIEMI, MATTI
Publication of US20040144513A1 publication Critical patent/US20040144513A1/en
Assigned to VALMET TECHNOLOGIES, INC. reassignment VALMET TECHNOLOGIES, INC. CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). Assignors: METSO PAPER, INC.
Abandoned legal-status Critical Current

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Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F1/00—Wet end of machines for making continuous webs of paper
    • D21F1/66—Pulp catching, de-watering, or recovering; Re-use of pulp-water

Definitions

  • the invention relates to a process arrangement in the short circulation of a paper machine comprising devices for dilution of thick stock, centrifugal cleaners, and a headbox fan pump, as well as a pipe system connecting these.
  • the invention also relates to a method in the short circulation of a paper machine for keeping the pressure constant on the suction side of a headbox fan pump, in which method the stock is diluted to headbox consistency, cleaned by centrifugal cleaners and pumped through a headbox to a wire section of the paper machine.
  • the deaeration tank is generally provided with an overflow or with liquid-level control, in which connection its function is not only to remove air from the system but also to ensure that the pressure is even on the suction side of the headbox fan pump.
  • Arrangements are also known in which there is no deaeration tank in the main line.
  • the arrangement has generally comprised a double-diluted system. In that connection, the thick stock is diluted first to a consistency required by centrifugal cleaning and the final dilution to headbox consistency is carried out only after centrifugal cleaners.
  • the dilutions are accomplished by passing the thick stock into a wire water flow which is at a back-pressure which has been made constant. By this means it can be assured at the same time that the pressure on the suction side of the headbox fan pump remains constant.
  • double-dilution cannot be used when paper grades requiring a high headbox consistency are manufactured, such as SC paper, LWC paper, and newsprint.
  • An object of the invention is to solve in a new way the problem of keeping the pressure constant on the suction side of the headbox fan pump.
  • the aim is to find an alternative arrangement for the double-dilution of the stock and for the deaeration tank of the main line which have been traditionally used for this purpose.
  • a pipeline is arranged which leads direct to the headbox fan pump without any deaeration and/or dilution stages usually provided in between.
  • a secondary line is connected to this pipeline between centrifugal cleaners and the fan pump for passing through it part of the stock flow coming from the accept side of the centrifugal cleaners as a return flow back to dilution devices of the thick stock such that the return flow enters the suction side of a mixing pump centrally and parallel to a dilution flow.
  • the return location has been selected so to avoid disturbances.
  • the purpose of the secondary line is to reduce flow and pressure variations of the accept side of the centrifugal cleaning.
  • valve can be used in the secondary flow.
  • the valve is, however, not absolutely necessary.
  • the process arrangement in accordance with the invention is simple and the number of tanks and devices needed in it is smaller than that of conventional arrangements.
  • the arrangement also reduces in neutral processes the precipitation of calcium compounds in the headbox approach pipe system, which results from the fact that, when calcium carbonate used as a filler is passed into a deaerator, part of the carbon dioxide contained in the carbonate is released.
  • the distance to the approach pipe system is longer and the filler flow through the deaerator is smaller.
  • FIG. 1 is a schematic view of part of the conventional short circulation of a paper machine.
  • FIG. 2 is a schematic view of the process arrangement in accordance with the invention.
  • FIG. 3 shows a variant of the process arrangement of FIG. 2.
  • FIG. 1 is a simplified illustration of part of the short circulation of a paper machine and, in particular, a conventional headbox approach system.
  • Thick fresh stock M is passed to a mixing area 11 of a wire pit 10 , where it is diluted with wire water to a consistency required by centrifugal cleaning, which consistency in this case is almost the same as the consistency of the stock to be fed to the headbox.
  • a diluted stock flow F 1 is passed through a mixing pump 12 to centrifugal cleaners 14 , in which heavy debris like sand is removed from the stock.
  • a cleaned stock flow F 2 is passed to a deaeration tank 15 , in which there is an air space with underpressure above the free surface of the stock.
  • a stock flow F 3 is passed from the lower part of the deaeration tank 15 to the suction side of a headbox fan pump 16 and therefrom further to machine screens 18 .
  • a stock flow F 4 is passed from the accept side of the machine screens 18 to a headbox 20 , which supplies the stock to a wire section of the paper machine (not shown).
  • Wire water F 10 recovered from the wire section is passed to the wire pit 10 for use in the dilution of the thick stock M.
  • the liquid level in the deaeration tank 15 is kept constant by means of an overflow 15 a, which is passed as a return flow F 5 into connection with the wire pit 10 for use in the dilution of the thick stock M.
  • the wire pit 10 also comprises an overflow 10 a
  • the wire pit 10 provided with the liquid-level control 10 a keeps the pressure constant on the suction side of the mixing pump 12 and, similarly, the deaeration tank 15 provided with the liquid-level control 15 a keeps the pressure constant on the suction side of the fan pump 16 .
  • FIG. 2 shows the short circulation of a paper machine in accordance with the invention, which short circulation is provided with centrifugal cleaning and single dilution and does not comprise any deaeration tank at all in the main line.
  • Thick stock M is diluted in the lower part of a wire pit 10 and a diluted stock flow F 1 is pumped by a mixing pump 12 to centrifugal cleaners 14 .
  • the bulk of the accept from the first stage of the centrifugal cleaners 14 is passed as a stock flow F 6 along a pipeline 30 direct to a headbox fan pump 16 , which pumps it further to machine screens 18 .
  • An accept flow F 4 from the first stage of the machine screens 18 is passed after that to a headbox 20 and further to a wire section of the paper machine.
  • a secondary line 32 is arranged in the pipeline 30 leading from the accept side of the centrifugal cleaners 14 to the fan pump 16 , through which secondary line part of the accept stock is passed as a return flow F 7 into connection with the wire pit 10 for use in the dilution of the thick stock M. Because of the free by-pass circulation, the pressure remains constant in the pipeline 30 on the suction side of the fan pump 16 . It is also possible to introduce other process flows smaller than that of the main line into the secondary line 32 (not shown in the figure).
  • FIG. 3 The arrangement of FIG. 3 is mainly similar to that of FIG. 2, for also in it a diluted stock flow F 1 is pumped through centrifugal cleaners 14 to a fan pump 16 , which pumps a stock flow F 6 further through machine screens 18 to a headbox 20 , and part of the centrifugally cleaned stock is passed as a return flow F 7 through a secondary line 32 back for the dilution of the stock.
  • the arrangement differs from that of FIG. 2 in that the thick stock M is diluted without a wire pit in a closed mixing volume 13 as so-called pipe dilution.
  • the thick stock M, wire water F 10 and the return flow F 7 of the centrifugally cleaned stock are passed to the mixing volume 13 situated on the suction side of the fan pump 12 as parallel flows such that the incoming thick stock flow M is surrounded by the return flow F 7 of diluted stock and the wire water flow F 10 is farthest outside.
  • the use of pipe dilution reduces further the tank and flow volume needed in the short circulation.
  • the process arrangement in accordance with the invention is particularly suitable for paper or board machines of the kind in which centrifugal cleaning is needed but double dilution cannot be used because of a high headbox consistency and, for reasons of process technology and economy, it is not desirable to use deaeration of the stock.
  • the method is also suitable for use in multi-layer web forming, in which stock suspensions intended for different stock layers are treated separately before forming a multi-layer web.

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  • Paper (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)
US10/475,504 2001-04-23 2002-04-12 Method and process arrangement in the short circulation of a paper machine Abandoned US20040144513A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
FI20010830 2001-04-23
FI20010830A FI111391B (fi) 2001-04-23 2001-04-23 Menetelmä ja prosessijärjestely paperikoneen lyhyessä kierrossa
PCT/FI2002/000311 WO2002086233A1 (en) 2001-04-23 2002-04-12 Method and process arrangement in the short circulation of a paper machine

Publications (1)

Publication Number Publication Date
US20040144513A1 true US20040144513A1 (en) 2004-07-29

Family

ID=8561032

Family Applications (1)

Application Number Title Priority Date Filing Date
US10/475,504 Abandoned US20040144513A1 (en) 2001-04-23 2002-04-12 Method and process arrangement in the short circulation of a paper machine

Country Status (7)

Country Link
US (1) US20040144513A1 (fi)
EP (1) EP1399621B1 (fi)
CN (1) CN1243880C (fi)
AT (1) ATE338845T1 (fi)
DE (1) DE60214546T2 (fi)
FI (1) FI111391B (fi)
WO (1) WO2002086233A1 (fi)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FI113971B (fi) * 2003-02-11 2004-07-15 Metso Paper Inc Laitteisto ja menetelmä paperikoneen tai vastaavan perälaatikolle johdetun massan käsittelyssä
FI115234B (fi) * 2003-09-24 2005-03-31 Metso Paper Inc Menetelmä kerrostetun paperi- tai kartonkirainan valmistamiseksi
DE102004054236B4 (de) * 2004-11-10 2007-06-06 Voith Patent Gmbh Verfahren zum Mischen von Suspensionen mit unterschiedlichen Zusammensetzungen
FI123392B (fi) * 2008-02-22 2013-03-28 Upm Kymmene Oyj Menetelmä kalsiumkarbonaatin saostamiseksi kuiturainaprosessin yhteydessä ja kuiturainakoneen lähestymisjärjestelmä
DE102010038694A1 (de) * 2010-07-30 2012-02-02 Voith Patent Gmbh Konstantteil

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6200417B1 (en) * 1998-06-29 2001-03-13 Voith Sulzer Papiertechnik Patent Gmbh Process and device for mixing stock suspensions
US6210529B1 (en) * 1998-06-10 2001-04-03 Valmet Corporation Method for regulating the surface level and consistency in a tank for metering component stock
US6267845B1 (en) * 1998-06-10 2001-07-31 Valmet Corporation Process arrangement for the short circulation in a paper or board machine

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6210529B1 (en) * 1998-06-10 2001-04-03 Valmet Corporation Method for regulating the surface level and consistency in a tank for metering component stock
US6267845B1 (en) * 1998-06-10 2001-07-31 Valmet Corporation Process arrangement for the short circulation in a paper or board machine
US6200417B1 (en) * 1998-06-29 2001-03-13 Voith Sulzer Papiertechnik Patent Gmbh Process and device for mixing stock suspensions

Also Published As

Publication number Publication date
FI111391B (fi) 2003-07-15
ATE338845T1 (de) 2006-09-15
EP1399621A1 (en) 2004-03-24
WO2002086233A1 (en) 2002-10-31
CN1503865A (zh) 2004-06-09
DE60214546T2 (de) 2007-08-30
FI20010830A (fi) 2002-10-24
CN1243880C (zh) 2006-03-01
DE60214546D1 (de) 2006-10-19
EP1399621B1 (en) 2006-09-06
FI20010830A0 (fi) 2001-04-23

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Legal Events

Date Code Title Description
AS Assignment

Owner name: METSO PAPER, INC., FINLAND

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:HIETANIEMI, MATTI;REEL/FRAME:014431/0347

Effective date: 20040308

STCB Information on status: application discontinuation

Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION

AS Assignment

Owner name: VALMET TECHNOLOGIES, INC., FINLAND

Free format text: CHANGE OF NAME;ASSIGNOR:METSO PAPER, INC.;REEL/FRAME:032551/0426

Effective date: 20131212