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WO2002097191A1 - Ensemble d'apport de pate a papier dans une machine a papier ou a carton - Google Patents

Ensemble d'apport de pate a papier dans une machine a papier ou a carton Download PDF

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Publication number
WO2002097191A1
WO2002097191A1 PCT/FI2002/000360 FI0200360W WO02097191A1 WO 2002097191 A1 WO2002097191 A1 WO 2002097191A1 FI 0200360 W FI0200360 W FI 0200360W WO 02097191 A1 WO02097191 A1 WO 02097191A1
Authority
WO
WIPO (PCT)
Prior art keywords
stock
delay loop
feed arrangement
attenuation device
chest
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.)
Ceased
Application number
PCT/FI2002/000360
Other languages
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
Publication of WO2002097191A1 publication Critical patent/WO2002097191A1/fr
Anticipated expiration legal-status Critical
Ceased 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
    • 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
    • D21F1/08—Regulating consistency
    • 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 stock feed arrangement for a paper or board machine according to the preamble of claim 1.
  • the conventional stock feed arrangement of the paper or board machine comprises a storage chest for each component stock, from which storage chest the component stock is fed by a pump to a proportioning chest of the component stock in question or directly to a blend chest of the component stocks. From the proportioning chest, the component stock is fed by a pump and metered by a valve to a common duct leading to the blend chest of the component stocks. The stock is fed by a pump from the blend chest to a machine chest. From the machine chest, the stock is fed by a pump through operating speed control or basis weight valve control to the short circulation. The machine chest is generally provided with an overflow back to the blend chest. The dilution of the stock takes place in several stages.
  • the stock is diluted in the bottom part of the storage chest to a consistency of about 4-5 % if it is at a consistency of about 10-14 % in the upper part of the storage chest.
  • the stock is diluted in a duct between the storage chest and the proportioning chest such that the consistency in the proportioning chest is about 3.5 %.
  • the proportioning chest there is additionally heavy agitation for equalizing consistency.
  • the stock is diluted in a duct between the blend chest and the machine chest such that the consistency in the machine chest is about 3 %.
  • the thick stock is then fed to the short circulation, i.e. to a wire pit placed in the short circulation.
  • the thick stock is diluted in the wire pit to a headbox consistency of about 1 %.
  • the blend chest and the machine chest form an equalizing unit for the stocks and the stock is diluted in them to the final metering consistency. In addition, they ensure even metering of the machine stock. Attempts are made to maintain a constant liquid level in the blend chest all the time.
  • FI patent 103676 describes one newer process arrangement for the short circulation of a paper or board machine.
  • this process arrangement marketed under the trademark OptiFeedTM
  • Thick component stocks are metered from a proportioning chest into a closed mixing volume, in which the component stocks are mixed and diluted in a dilution water flow to a consistency of about 1.5 %.
  • the stock is fed in a closed space through cleaning stages and, when needed, through deaeration to a headbox.
  • the stock is diluted further to a headbox consistency of about 1.0 %.
  • FI patent 104384 describes an apparatus and a method for mixing fresh stock and wire water passed from a wire pit.
  • the apparatus comprises a first pipe which leads from a machine chest through a return water chest and extends to the bottom part of the wire pit.
  • the apparatus additionally comprises a second pipe extending from the return water chest to the bottom part of the wire pit.
  • the first pipe is passed from the return water chest onwards centrally inside the second pipe.
  • the first pipe extends a little farther into the wire pit than the second pipe.
  • a mixing point is formed in connection with the ends of the pipes.
  • the circumferential line of at least the inner and/or the outer surface of the wall of the first pipe is wave- shaped at the mixing point. This kind of arrangement provides efficient mixing of fresh stock, return water and wire water.
  • disturbances which occur in the stock flow in the range of 2 s to 2 min.
  • These disturbances can be consistency disturbances which are due, for example, to the arching of the storage tower of a component stock.
  • Stock pieces of high consistency separating from the inner surface of the storage tower cause peaks in the consistency of the storage tower.
  • consistency variations which cause consistency variations in the storage tower.
  • the disturbances may also be variations in refining, which are due to variations in the refining degree of the pulp fed into the storage tower.
  • disturbances may be caused by variations in the filler content of the broke which is removed from the process and recovered for use.
  • This broke recovered from the process is passed to a storage tower from which it is fed again to the process. Variations of the filler content also occur in the stock recovered in the disc filter. The stock recovered in the disc filter is also passed to a storage tower, from which it is fed again to the process.
  • thick stock feed arrangements are meant the stock feed arrangements between the storage towers of component stocks and the short circulation. On entering the short circulation, the consistency of the stock is generally over 2 %.
  • the aim of the invention is to provide a thick stock feed arrangement for a paper or board machine in which the disturbances occurring in the stock flow in the range of 2 s to 2 min are attenuated before the stock is fed to the short circulation.
  • the disturbances in the thick stock flow in said range have been attenuated, the basis weight variations of the machine stock arising from the consistency variations of the machine stock are also reduced.
  • the stock feed arrangement for a paper or board machine according to the invention is mainly characterized by the disclosure in the characterizing part of claim 1.
  • At least one attenuation device is placed in the stock feed portion between a storage tower and the short circulation.
  • the stock feed arrangement of a paper or board machine in accordance with the invention can be applied in all kinds of paper or board machines.
  • Figure 1 is a schematic view of one stock feed arrangement for a paper or board machine in accordance with the invention, in which arrangement an attenuation device is placed between the storage tower of each component stock and the proportioning chest of the component stock and/or between the machine chest and the wire pit.
  • Figure 2 is a schematic view of a second stock feed arrangement for a paper or board machine in accordance with the invention, in which arrangement an attenuation device replaces the blend and machine chests.
  • Figure 3 is a schematic view of a third stock feed arrangement for a paper or board machine in accordance with the invention, in which arrangement an attenuation device is placed between a proportioning chest and a closed mixing volume.
  • Figure 4 is a schematic view of one attenuation device, seen from above, suitable for the arrangement in accordance with the invention.
  • Figure 5 is a cross-sectional view of the mixing point of the attenuation device shown in Fig. 4.
  • Figure 6 is a schematic view of one alternative attenuation device, seen from above, suitable for the arrangement in accordance with the invention.
  • Figure 7 is a view of principle of how a short-period disturbance occurring in the stock flow is attenuated by means of the attenuation device in accordance with the invention.
  • Fig. 1 is a schematic view of a conventional stock feed arrangement of a paper or board machine provided with a blend chest 12 and a machine chest 14 as well as with a wire pit 120.
  • Each component stock is fed from its own storage tower 8 A, 8B, 8C by means of storage tower feed pumps 9A, 9B, 9C to a proportioning chest 10 A, 10B, 10C of the component stocks.
  • a proportioning chest 10A, 10B, 10C From the proportioning chest 10A, 10B, 10C, each component stock is fed by means of metering pumps 11 A, 11B, 1 IC to the blend chest 12.
  • the stock is fed from the blend chest 12 by means of a mixing pump 13 to the machine chest 14.
  • fresh stock Mj is fed by means of a machine chest pump 15 to the bottom part of the wire pit 120.
  • the stock is fed by means of a wire pit pump 121 through a centrifugal cleaner 122 to a deaeration tank 111.
  • the stock is fed from the deaeration tank 111 by means of a headbox feed pump 109 through a machine screen 110 to a headbox 106.
  • the stock is fed to a forming section 107.
  • the fibre-containing wire water removed from the web in the fo ⁇ ning section is recovered and fed to the wire pit 120, and there is an overflow from the deaeration tank 111 to the bottom part of the wire pit 120.
  • the fresh stock M T and the overflow from the deaeration tank 111 are mixed together and diluted with wire water to the headbox consistency (about 1 %).
  • the mixing principle described in the above-mentioned FI patent 104384 can be applied.
  • Sand and other possible heavy and large-sized (over 20 ⁇ m) contaminations are removed from the stock in the centrifugal cleaner 122.
  • the air carried with the wire water and the stock is removed from the stock by means of vacuum.
  • the machine screen 110 forms the last cleaning stage before the stock is supplied into the headbox 106.
  • An attenuation device 20A, 20B, 20C in accordance with the invention is placed after the feed pump 9A, 9B, 9C of the storage tower 8a; 8B, 8C of each component stock before the proportioning chest 10A, 10B, 10C of each component stock.
  • a corresponding attenuation device 20 is also placed after the pump 15 of the machine chest.
  • the portion of the stock feed arrangement associated with the short circulation LK is indicated with a broken line.
  • the stock feed arrangement leading from the storage towers 8 A, 8B, 8C to the wire pit 120 is called here a thick stock feed arrangement.
  • Fig. 2 shows a second stock feed arrangement in accordance with the invention, which arrangement differs from the feed arrangement shown in Fig. 1 in respect of the blend chest and the machine chest.
  • Fig. 2 does not show the stock feed portion between storage towers 8A, 8B, 8C (Fig. 1) and proportioning chests 10A, 10B, 10C, which portion can be similar to that of Fig. 1.
  • the blend chest and the machine chest have been replaced with an attenuation device 20.
  • Each component stock is fed from its own proportioning chest 10A, 10B, IOC by means of metering pumps 11 A, 11B, 11C to the attenuation device 20, in which the component stocks are mixed and the flow is stabilized.
  • the fresh stock is fed to the bottom part of a wire pit 120, as in the embodiment shown in Fig. 1.
  • the short circulation LK corresponds to that shown in Fig. 1 and it is also here indicated by a broken line.
  • Fig. 3 shows a stock feed arrangement which is marketed under the trademark OptiFeed TM and in which the blend and machine chests as well as the wire pit have been eliminated. Fig. 3 also does not show the stock feed portion between storage towers 8A, 8B, 8C (Fig. 1) and proportioning chests 10A, 10B, 10C, which portion may be like the one shown in Fig. 1.
  • component stocks are fed from the proportioning chests 10A, 10B, 10C by means of metering pumps 11 A, 11B, 11C into a closed mixing volume 100, in which the component stocks are mixed in a dilution water flow that is passed from a deaeration tank 111.
  • the stock is fed by means of a first feed pump 101 of the main line through a screen 102 and centrifugal cleaning 103 to the suction side of a second feed pump 104 of the main line, where the stock is diluted to the headbox consistency by a dilution water flow passed from the deaeration tank 111.
  • the stock diluted to the headbox consistency is fed by the second feed pump 104 of the main line through a machine screen 105 to a headbox 106.
  • a dilution headbox 106 is used and a dilution water flow is fed from the deaeration tank 111 by means of a dilution water pump 130 through a screen 131.
  • the wire water recovered from a forming section 107 is fed by means of a wire water pump 108 to the deaeration tank 111.
  • An attenuation device 20A, 20B, 20C in accordance with the invention is placed after each metering pump 11 A, 11B, 11C, which device enables the disturbances in each component stock flow in the period range of 2 seconds to 2 minutes to be attenuated.
  • the component stocks can also be passed to a single attenuation device, but in that case the volume of the attenuation device must be tliree times larger. In that connection, all component stocks are passed to this common attenuation device, in which the component stocks are mixed together. After that, the stock is passed to the closed mixing volume 100, in which the stock is mixed and diluted in the dilution water flow.
  • the attenuation device 20A, 20B, 20C is described in greater detail in connection with Figs. 4-6.
  • Fig. 3 the portion of the stock feed arrangement belonging to the short circulation LK is indicated by a broken line.
  • Fig. 4 is a schematic view of an attenuation device 20, 20A, 20B, 20C, seen from above, used in the stock feed arrangement in accordance with the invention
  • Fig. 5 shows a cross section of the mixing point of the attenuation device shown in Fig. 3.
  • the attenuation device is formed of an inlet duct 21, a delay loop duct 22 and an outlet duct 23.
  • the stock is introduced into the attenuation device from the inlet duct 21, after which the stock is arranged to flow around the delay loop duct 22.
  • the stock exits from the delay loop duct 22 through the outlet duct 23.
  • the inlet duct 21 opens centrally into the delay loop duct 22 such that the flow direction of the stock flowing from the discharge opening of the inlet duct 21 into the delay loop duct 22 is substantially tangential to the wall of the delay loop duct 22.
  • the outlet duct 23 is formed of two branches
  • the opening locations of the branches 23a, 23b are situated opposite each other such that the line segment connecting the centres of the cross sections of the opening locations passes through the centre of the cross section of the delay loop duct 22.
  • the branches 23a, 23b of the outlet duct 23 join after some distance forming a single outlet duct 23.
  • the first branch 23a of the outlet duct 23 is here longer than the second branch 23b. The stock flow moving in the longer branch
  • the delay loop duct 22 shown in Fig. 4 is circular.
  • Fig. 6 is a schematic view of an alternative attenuation device 20, seen from above, used in the stock feed arrangement in accordance with the invention, which device differs form the attenuation device shown in Fig. 3 in respect of the shape of the delay loop duct 22.
  • the delay loop duct 22 forms here a rectangle provided with rounded corners.
  • the inner wall of the inlet duct 21 is additionally provided with fluidization members 24 for fluidizing the incoming flow of the stock.
  • a mixing valve 25 In the discharge opening of the inlet duct 21 there is a mixing valve 25 by which the mixing of the stock fed from the inlet duct 21 with the stock flowing in the delay loop duct 22 can be enhanced.
  • the inner wall of the delay loop duct 22 is in turn provided with mixing members 26 spaced from the discharge opening of the inlet duct 21, by which members the mixing in the delay loop duct 22 is further enhanced.
  • an active mixing device needing external energy for example, a mixing device of the propeller type, can be placed in the delay loop duct 22.
  • a mixing device of the propeller type By the propeller-type mixing device, pumping energy is also introduced into the stock flow.
  • the cross section of the delay loop duct 22 is substantially round, so that its flow properties are good. From the standpoint of the invention, this is, however, not essential, but the cross section of the delay loop duct 22 can be of any shape.
  • the mixing principle described in the above-mentioned FI patent 104384 can be applied in the portion of the inlet duct 21 extending into the delay loop 22.
  • the circumferential line of the inner and/or the outer surface of the inlet duct 21 or at least part of it is wave-shaped.
  • the inner surface of the delay loop duct 22 can also be formed to be wave-shaped at the discharge opening of the inlet duct 22 and in the flow direction some distance onwards from it.
  • Fig. 7 is a view of principle of how a short-period disturbance occurring in the stock flow is attenuated by means of the attenuation device in accordance with the invention.
  • the curve 1) represents a short-period disturbance occurring in the stock flow
  • the curve 2) represents the attenuation of this disturbance as a function of time by means of the attenuation device in accordance with the invention.
  • the curve 3) in turn represents the attenuation of the disturbance in a situation in which the outlet duct 23 is formed of two branches 23 a, 23b of different lengths .
  • an attenuation device in accordance with the invention is placed in the feed line of each component stock before 20A, 20B, 20C the proportioning chests 10A, 10B, IOC of the component stocks and in the feed line of the machine stock before 20 the wire pit 120.
  • the thick stock feed arrangement in accordance with the invention there is at least one of these attenuation devices 20, 20A, 20B, 20C between the storage tower 8A, 8B, 8C and the short circulation LK, but it is also possible to place them at several locations, as is the case in Fig. 1.
  • the attenuation device 20 used in the stock feed arrangement in accordance with the invention is dimensioned such that the cross-sectional area of the delay loop duct 22 is at least 5 times larger than the cross-sectional area of the inlet duct 21.
  • the cross-sectional area of the outlet duct 23 is in turn equal to the cross-sectional area of the inlet duct 21.
  • the combined cross-sectional area of these branches is equal to the cross-sectional area of the inlet duct 21. Shorter delays can be achieved by the delay loop 22 than by the chest because the chest requires a certain minimum volume for control of the liquid level.
  • the volume of the delay loop 22 will be 18 m 3 .
  • the volume of the delay loop 22 can be dropped on average to one third, i.e. to the value of 6 m 3 .

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  • Accessories For Mixers (AREA)
  • Paper (AREA)

Abstract

L'invention concerne un ensemble d'apport de pâte à papier, qui comprend un ensemble d'apport de pâte à papier épaisse et une circulation courte (LK). Cet ensemble d'apport de pâte à papier épaisse comprend au moins un dispositif d'atténuation (20, 20A, 20B, 20C) placé dans la partie d'apport de pâte à papier située entre les tours de stockage (8A, 8B, 8C) des constituants de pâte à papier et la circulation courte (LK), cette pâte à papier épaisse étant mise en circulation dans une boucle de retard (22) du dispositif d'atténuation afin d'atténuer les perturbations ayant lieu dans le débit de pâte à papier dans la plage de temps comprise entre 2 secondes et 2 minutes avant que la pâte à papier épaisse ne soit amenée à la circulation courte (LK).
PCT/FI2002/000360 2001-05-29 2002-04-26 Ensemble d'apport de pate a papier dans une machine a papier ou a carton Ceased WO2002097191A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI20011122A FI109300B (fi) 2001-05-29 2001-05-29 Paperi- tai kartonkikoneen massan syöttöjärjestely
FI20011122 2001-05-29

Publications (1)

Publication Number Publication Date
WO2002097191A1 true WO2002097191A1 (fr) 2002-12-05

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/FI2002/000360 Ceased WO2002097191A1 (fr) 2001-05-29 2002-04-26 Ensemble d'apport de pate a papier dans une machine a papier ou a carton

Country Status (2)

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FI (1) FI109300B (fr)
WO (1) WO2002097191A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009021804A1 (fr) * 2007-08-11 2009-02-19 Voith Patent Gmbh Partie constante pour une machine à papier

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999064668A1 (fr) * 1998-06-10 1999-12-16 Valmet Corporation Processus de la circulation courte d'une machine a papier ou a carton
WO1999064666A1 (fr) * 1998-06-05 1999-12-16 Valmet Corporation Procede et equipement d'une machine de fabrication du papier ou du carton pour melanger la pate de papier fraiche et de l'eau utilisee pour diluer la pate

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999064666A1 (fr) * 1998-06-05 1999-12-16 Valmet Corporation Procede et equipement d'une machine de fabrication du papier ou du carton pour melanger la pate de papier fraiche et de l'eau utilisee pour diluer la pate
WO1999064668A1 (fr) * 1998-06-10 1999-12-16 Valmet Corporation Processus de la circulation courte d'une machine a papier ou a carton

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009021804A1 (fr) * 2007-08-11 2009-02-19 Voith Patent Gmbh Partie constante pour une machine à papier

Also Published As

Publication number Publication date
FI109300B (fi) 2002-06-28
FI20011122A0 (fi) 2001-05-29

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