EP0639667A1 - Vorrichtung für eine Papier- oder Pappemaschine und deren Anwendung - Google Patents

Vorrichtung für eine Papier- oder Pappemaschine und deren Anwendung Download PDF

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Publication number
EP0639667A1
EP0639667A1 EP94850139A EP94850139A EP0639667A1 EP 0639667 A1 EP0639667 A1 EP 0639667A1 EP 94850139 A EP94850139 A EP 94850139A EP 94850139 A EP94850139 A EP 94850139A EP 0639667 A1 EP0639667 A1 EP 0639667A1
Authority
EP
European Patent Office
Prior art keywords
roll
pressure
suction
fabric
shell
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.)
Withdrawn
Application number
EP94850139A
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English (en)
French (fr)
Inventor
Reijo Orava
Seppo Karine
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.)
Stora Enso Oyj
Original Assignee
Enso Gutzeit 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 Enso Gutzeit Oy filed Critical Enso Gutzeit Oy
Publication of EP0639667A1 publication Critical patent/EP0639667A1/de
Withdrawn legal-status Critical Current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
    • D21F1/48—Suction apparatus
    • D21F1/50—Suction boxes with rolls

Definitions

  • the present invention relates to an apparatus in accordance with the preamble of claim 1 for use in a paper/board machine.
  • the functions of the wire section have been characterized by the concomitant increase of the wire section frictional load with the increase of the machine speed as higher vacuum is required due to the need for keeping the solids at a constant level.
  • a major portion of the frictional wire load occurs in the region of the wet suction box, where the wire is sucked against the suction box surface with a high force that is exerted over a large area.
  • the flat suction box has a limited water removal capability. Its effect can be increased by using a higher vacuum, whereby also the friction between the box cover surface and the wire increases, which results in greater wire wear and shorter life.
  • the friction sets the limit to the maximum usable vacuum in the box. If the vacuum is above a certain limit, the wire stops from moving. In paper machines arming the sheet from pulp containing carbonate filler, the elevated friction causes rapid wire wear.
  • Moving vacuum belts made from rubber are capable of eliminating the friction caused by the vacuum, but the high vacuum employed results in sheet marking by the slot pattern of the belt. Rubber belts are extremely costly and difficult to service. Moreover, they are problematic to drive.
  • Felt suction box is a typical felt conditioner. Its operation requires a vacuum of 5-6 mH2O, which must be accomplished using suction pumps.
  • the felt suction box causes rather heavy felt wear on the side supporting the web and results in unnecessarily premature felt changes.
  • the amount of air flow through the suction box is crucial to the conditioning result. In new felts the air is freely sucked through the felt, but with the gradual plugging of the felt, the amount of air passing through the felt is reduced. Then, the water removal capability of the felt conditioner is impaired as the amount of air sucked through the felt is no longer sufficient to remove all water from the felt.
  • a permeable jacket roll is adapted in a pressure-tight chamber, advantageously a suction box.
  • the fabric-jacketed roll supports the running wire during the suction and provides a working time for the suction acting on the sheet between the box sealing strips that is several times longer and uninterrupted with regard to a perforated suction box.
  • the rotary suction box with the fabric-jacketed roll becomes the more effective the larger the fabric roll diameter, that is, the working time of the suction.
  • the suction capacity must be herein increased appropriately.
  • the benefit of the fabric roll over a conventional suction roll is its freedom from causing web marking, which facilitates the use of the present arrangement with extremely fine grades of paper and board.
  • the apparatus according to the invention which advantageously is a rotary fabric-roll suction box, said apparatus incorporating a pressure-tight chamber such as a vacuum or a pressure box, and in conjunction with said pressure-tight chamber is adapted a permeable jacket roll, advantageously a fabric-jacketed roll, is superior over the prior art with the benefits described below.
  • a flatbox, or a suction box wastes a portion of the vacuum energy as friction which at its worst hampers the driving of the wire (making the wire slip).
  • the rotary fabric-roll suction box according to the invention resists the running of the wire only by the amount of the friction occurring in its bearings.
  • the friction of a suction box causes the wire to wear from its underside. This effect may cause problems particularly in paper machines using filler-containing stock. Obviously, wear is faster, the higher the vacuum in the box. By contrast, no sliding friction occurs between the rotary fabric-roll suction box and the wire, consequently causing no wire wear due to friction.
  • a suction box is operated at the maximum vacuum still permitting the running of the wire and not yet causing excessive economical problems from wire wear.
  • a rotary fabric-roll suction box can be operated with a vacuum determined by the local situation or need. The limit of high vacuum is dictated by the structural strength of the roll. A moderate vacuum can be used in the rotary fabric-roll suction box still achieving good suction result (owing to the long working time of the vacuum), and the content of fine solids in the sheet can be kept higher than with the use of a suction box.
  • the vacuum reserve of a suction box is available at the distance of the ceramic box cover from the sheet.
  • the rotary fabric-roll suction box puts the vacuum reserve at the sheet surface by virtue of the open structure of the roll and the wire. Consequently, the efficiency of the suction provided by the fabric roll is better than that of the suction box.
  • the suction working time provided by the rotary fabric-roll suction box is several times (depending on the fabric roll diameter and box geometry) that achievable by the use of a suction box.
  • a suction box the vacuum is cut off after each hole of the perforation. In other words, a portion of the vacuum energy is used at each hole for restarting the suction work.
  • the vacuum prevails over the entire machine-directional width of the suction box opening, whereby energy is lost only once for starting the suction work.
  • the unit price of the rotary fabric-roll suction box is in the same order with suction boxes it replaces.
  • the vacuum arrangement is simpler than that of a suction box, requiring less expenditure in the erection of new installations. Due to the lower energy losses of the rotary fabric-roll suction box, the operating costs are reduced.
  • a suction roll of the paper machine can normally be operated with the maximum vacuum permitted the sheet quality and physical laws (temperature). Analogously to the suction roll, the usable maximum vacuum in the rotary fabric-roll suction box is limited by the roll construction or sheet temperature.
  • the rotary fabric-roll suction box system is free from the sheet marking tendency.
  • the proportion of suction holes drilled on a suction roll shell is normally only approx. 50 % of the suction roll surface, whereby the drilling pattern of the suction roll easily marks the sheet if the solids content of the sheet is too low when reaching the suction roll.
  • the rotary fabric-roll suction box system achieves a significantly longer vacuum zone along the machine-directional travel of the sheet as the vacuum prevails in the box enclosing the fabric roll.
  • the vacuum zone length is limited by the arc covered by suction box adapted to the inside of the suction roll.
  • the vacuum zone of a suction roll in the machine direction covers approx. 100 mm, while in a rotary fabric-roll system the vacuum zone can have a length in excess of 200 mm.
  • the vacuum reserve In a suction roll the vacuum reserve is displaced at a distance (approx. 70-80 mm) of the roll shell thickness from the point of suction. In a rotary fabric-roll system the vacuum reserve is located immediately under the wire. This is because all flow-choking constrictions are eliminated from the system.
  • a suction roll is expensive due to special materials and manufacturing methods required.
  • the fabric-jacketed roll has simpler construction and is accordingly cheaper to manufacture.
  • a suction roll is difficult to clean due to its closed structure. Owing to its opens structure, the fabric roll/suction box system is easy to clean.
  • All servicing points of a suction roll are located to the interior of the roll with the exception of the bearings, requiring the removal of the roll from the machine and dismantling thereof for scheduled maintenance.
  • all essential service-requiring component of the rotary fabric-roll system are located on the outer surface of the apparatus, where they can be serviced or replaced during a shut-down without the need for removal of the apparatus from the paper machine.
  • the only exception is the fabric jacket of the roll (a wire jacket).
  • the fabric roll causes a small bump on the wire travel, but eliminates almost entirely the sliding friction. Hence, the only resistance to the wire travel is comprised by the friction of the support strips and the rotational friction of the bearings.
  • the rotary fabric-roll suction box facilitates the use of demand-controlled pressure gradient for water removal at the outgoing end of the wire section, which in multi-ply sheet formation improves bonding between the plies, and in all sheet formation elevates the solids content. In terms of specific suction energy consumption, the rotary fabric-roll suction box provides higher economy than a set of suction boxes with a corresponding effective area of suction openings.
  • the rotary fabric-roll suction box is capable of replacing 3-5 suction boxes of equal size.
  • the cost of the rotary fabric-roll suction box is only a fraction of the cost of a suction roll and a moving slotted-rubber vacuum belt. It is quieter and can be operated with smaller pressure gradient due to its longer suction working time. Accordingly, the vacuum can be produced using a suction fan which needs less energy than a liquid-ring pump. Reduced wear also means less wire wear and extended wire life. Successful suction action with a reduced pressure gradient helps keeping the fine solids in the sheet, whereby the final product smooothness is improved.
  • the rotary fabric-roll suction box system is easier to keep clean than a suction roll and a suction box as the mixture of suction air and drained water passes through the fabric roll from roll inside radially outward on the opposite side to that facing the wire thus removing particulate matter adhering to the roll surface.
  • the vacuum box into which the fabric roll is adapted must be rigid enough to support the vacuum without dimensional changes.
  • the fabric roll must take the forces imposed by the vacuum prevailing in the vacuum box without any bending or dimensional changes. If the roll shaft is designed to extend through the entire length of the roll, the free space formed between the shaft and the shell of the roll must be at least half the width of the suction opening in order to avoid choking of the suction flow in the suction working area due to obstructions in the roll construction.
  • the proportion of suction openings on the roll shell must be as high as possible to achieve as homogeneous vacuum at each point of the shell surface as possible.
  • the roll shell is jacketed by a shrinkable fabric with a mesh of four yarns per centimeter, for instance.
  • a permeable fabric serves for optimally equalizing the vacuum over the entire area of the suction opening by slightly displacing the running wire from the roll shell surface.
  • a pressure box fed with heated compressed air is adapted at the rotary fabric-roll suction box.
  • a wire section can be constructed by taking the wires of a twin-wire section in a zig-zag fashion for water removal so that a first rotary fabric-roll suction box is adapted to blow, a second is adapted to suck from the opposite side, and a third is again adapted to blow from the same side as the first rotary fabric-roll suction box.
  • the water removal always occurs in the same direction, whereby the best efficiency in water removal is achieved.
  • Under the blowing fabric-roll boxes is adapted a vacuum box similar to the blowing boxes, whereby air passage through the wire is augmented enhancing the drying result.
  • the vacuum level may not be adjusted so high that the vacuum-side wire is detached from the sheet.
  • the invention is further related to the use of the apparatus for a paper/board machine advantageously as a water removal unit, pressure-gradient dryer or felt conditioner.
  • a permeable jacket roll 1 advantageously a fabric-jacketed roll, is adapted to the inside of a pressure-tight chamber 2, advantageously a vacuum box.
  • the upper surface of the roll 1 remains over the top surface of the box 2.
  • the pressure gradient, advantageously a vacuum, provided by the box is exerted via the roll 1 and the wire 5 to a sheet 6 running on the wire. As the sheet 6 rests on the wire 5, the vacuum sucks the wire 5 against the fabric surface of the roll 7, whereby the roll 1 starts to rotate at the speed of the wire 5.
  • the sheet 6 running on the wire 5 is subjected to suction which prevails with a constant pressure gradient all the way from the incoming side sealing strip 3 to the outgoing side sealing strip 4 of the box 2.
  • the long working time of the suction makes the water removal action highly efficient, and the fabric jacket 7 equalizes the suction in a marking-free manner over the entire area of the suction opening.
  • FIGs. 3 and 4 such applications of the apparatus according to the invention are shown in which the pressure-tight chamber 2 is used as a pressure box.
  • the pressure box is advantageous in situations needing detachment of the sheet 6 from the wire 5, or alternatively, water removal from the sheet 6 in a direction opposite to the box.
  • the pressure box may be opposed by a vacuum box, whereby the vacuum may not, however, be adjusted so high as to detach the vacuum-side wire from the sheet.
  • the pressure-tight chamber 2 included in the apparatus is used as a pressure box.
  • the apparatus is advantageously placed at a location where the felt is maximally deflected.
  • a vacuum box for drainage of the water removed from the felt. So much heated air is passed to the pressure box 2 including the roll 1 that a continuous overpressure is established inside the roll 1.
  • the overpressure expels water contained in the felt, which action is further augmented by the centrifugal force generated by the felt travel about the perimeter of the rotating roll 1.
  • the vacuum trough placed on the opposite side of the felt is connected to a suction fan suited to produce a moderate vacuum to said opposite side of the felt.
  • the apparatus described herein is also well suited for use as a conditioner for a wet wire and a drying wire.
  • the apparatus according to the invention When equipped with a pressure box, the apparatus according to the invention is an excellent replacement for a wire guide shoe. Complementing the centrifugal action, the pressure gradient provided by the apparatus enhances water removal. Moreover, the wearing action imposed by the guide shoe on the wire is eliminated resulting in longer wire life.

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  • Paper (AREA)
EP94850139A 1993-08-17 1994-08-17 Vorrichtung für eine Papier- oder Pappemaschine und deren Anwendung Withdrawn EP0639667A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI933624A FI933624A (fi) 1993-08-17 1993-08-17 Paperi- ja kartonkikoneen laite sekä sen käyttö
FI933624 1993-08-17

Publications (1)

Publication Number Publication Date
EP0639667A1 true EP0639667A1 (de) 1995-02-22

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ID=8538429

Family Applications (1)

Application Number Title Priority Date Filing Date
EP94850139A Withdrawn EP0639667A1 (de) 1993-08-17 1994-08-17 Vorrichtung für eine Papier- oder Pappemaschine und deren Anwendung

Country Status (3)

Country Link
EP (1) EP0639667A1 (de)
CA (1) CA2130224A1 (de)
FI (1) FI933624A (de)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19728824A1 (de) * 1997-07-05 1999-01-07 Voith Sulzer Papiermasch Gmbh Saugwalze für eine Papiermaschine
US5968319A (en) * 1997-07-05 1999-10-19 Voith Sulzer Papiermaschinen Dual external suction boxes for suction roll for a paper machine
DE10221755A1 (de) * 2002-05-16 2003-11-27 Voith Paper Patent Gmbh Blattbildungsvorrichtung
WO2006090012A1 (en) * 2005-02-24 2006-08-31 Effcom Oy A device for removing liquid from a moving fabric or web
EP2132379A1 (de) * 2007-02-01 2009-12-16 Effcom Oy Überdruckapparat
WO2013190174A1 (en) 2012-06-21 2013-12-27 Effcom Oy An apparatus for removing liquid from a moving wire or web, and a method

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2270464A (en) * 1939-01-11 1942-01-20 Mary Jones Vacuum roll
FR2364291A1 (fr) * 1976-09-13 1978-04-07 Valmet Oy Procede et dispositif pour soumettre, dans une machine a papier, un feutre, une toile metallique et/ou une couche de suspension de fibres a une action d'aspiration

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2270464A (en) * 1939-01-11 1942-01-20 Mary Jones Vacuum roll
FR2364291A1 (fr) * 1976-09-13 1978-04-07 Valmet Oy Procede et dispositif pour soumettre, dans une machine a papier, un feutre, une toile metallique et/ou une couche de suspension de fibres a une action d'aspiration

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19728824A1 (de) * 1997-07-05 1999-01-07 Voith Sulzer Papiermasch Gmbh Saugwalze für eine Papiermaschine
US5968319A (en) * 1997-07-05 1999-10-19 Voith Sulzer Papiermaschinen Dual external suction boxes for suction roll for a paper machine
DE10221755A1 (de) * 2002-05-16 2003-11-27 Voith Paper Patent Gmbh Blattbildungsvorrichtung
WO2006090012A1 (en) * 2005-02-24 2006-08-31 Effcom Oy A device for removing liquid from a moving fabric or web
US7871495B2 (en) 2005-02-24 2011-01-18 Effcom Oy Device for removing liquid from a moving fabric or web
CN101133207B (zh) * 2005-02-24 2011-03-23 埃弗科姆公司 去除液体的装置及方法，以及该装置的应用
JP4842975B2 (ja) * 2005-02-24 2011-12-21 エフコム オサケユイチア 移動しているファブリック又はウェブから液体を除去するための装置
EP2132379A1 (de) * 2007-02-01 2009-12-16 Effcom Oy Überdruckapparat
EP2132379A4 (de) * 2007-02-01 2013-11-20 Effcom Oy Überdruckapparat
WO2013190174A1 (en) 2012-06-21 2013-12-27 Effcom Oy An apparatus for removing liquid from a moving wire or web, and a method

Also Published As

Publication number Publication date
CA2130224A1 (en) 1995-02-18
FI933624A (fi) 1995-02-18
FI933624A0 (fi) 1993-08-17

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