EP0321986A2 - Trockenpartie einer Papiermaschine - Google Patents

Trockenpartie einer Papiermaschine Download PDF

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Publication number
EP0321986A2
EP0321986A2 EP88121532A EP88121532A EP0321986A2 EP 0321986 A2 EP0321986 A2 EP 0321986A2 EP 88121532 A EP88121532 A EP 88121532A EP 88121532 A EP88121532 A EP 88121532A EP 0321986 A2 EP0321986 A2 EP 0321986A2
Authority
EP
European Patent Office
Prior art keywords
drying
guide surface
making machine
paper making
drying section
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Withdrawn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
EP88121532A
Other languages
English (en)
French (fr)
Other versions
EP0321986A3 (de
Inventor
Osmo Skyttä
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.)
Tampella Oy AB
Original Assignee
Tampella Oy AB
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 Tampella Oy AB filed Critical Tampella Oy AB
Publication of EP0321986A2 publication Critical patent/EP0321986A2/de
Publication of EP0321986A3 publication Critical patent/EP0321986A3/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Withdrawn legal-status Critical Current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
    • D21F5/00—Dryer section of machines for making continuous webs of paper
    • D21F5/02—Drying on cylinders
    • D21F5/04—Drying on cylinders on two or more drying cylinders
    • D21F5/042—Drying on cylinders on two or more drying cylinders in combination with suction or blowing devices

Definitions

  • the present invention relates to a drying section in a paper making machine as defined in more detail in the preamble of claim 1.
  • the invention is particularly intended for a high-speed paper making machine, whereby a wet and weak web coming from a press is supported in a manner that it remains intact also at rates of production substantially higher than at present.
  • the rate of production in paper making machines has in­creased along with technological development. Its pre­sent level is 20-25 m/s in the manufacture of newsprint or corresponding paper grades. A high rate of product­ion correlates directly with high output, i.e. reduced production costs. A condition for this is of course that a web to be produced remains undamaged. A break leads to interference and lower output. The forward end of the drying section in a modern high-speed paper making machine forms a point at which most breaks seem to occur.
  • a web couched with the wire section of a paper making machine still contains more than 80 % of water. It is removed from the web by compressing in a press section, usually down to a dry mater content of 40-45 %. The rest of the water must be removed by evaporation. This is effected by allowing the web to pass over hot drying cylinders. The web is pressed to the surface of a dry­ing cylinder by means of a draining wire for maximum heat transfer contact. The amount of necessary thermal energy is great and, thus, a plurality of drying cyl­inders are required, in practice appr. 50 drying cyl­ inders. Those are usually provided as several operat­ing arrays, generally 4-7 arrays.
  • An object of this invention is to overcome all the above problems. At the same time it will be unnecess­ary to use a so-called rope system which is required in the prior known solution for re-passing a web through the machine after a break.
  • a drying section of a paper making machine of the invention is mainly characterized by what is set forth in the characterizing clause of claim 1. Further advant­ageous features of the drying section according to the invention are evident from the dependent claims.
  • the drying cylinders are preferably disposed in a single row. A draining wire runs over them in a traditional way.
  • the lower cylinders are left out and replaced with a guide surface which is substantially of the same width as the web and based on coanda-effect.
  • the guide surface is preferably a two-piece U-shape which is mount­ted symmetrically relative to the straight line running through the centre of a roll between the drying cylin­ders and perpendicular to the straight line connecting the centres of the drying cylinders in a manner that both pieces fold the web appr. 90°. Between the pieces remains a gap for allowing the chaff formed in a web break to fall into the basement of a machine.
  • the guide surface is preferably mounted to be carried by movable supporting arms or the like in a manner that its distance from the drying cylinders and a roll there­between can be adjusted as the machine is running. This is necessary for the reason that, due to said stretch­ing tendency of a web, a possible excessive slack in a web loop can be eliminated by drawing the guide surface away from the drying cylinders. Furthermore, when starting a paper making machine or after a break, the edge trimming can be passed quickly and safely through the machine by using the guide surfaces without a risk of damage and unreliable leader ropes with their access­ories.
  • the guide surfaces are technical strictlyly simple and inexpensive to manufacture as they can be made of e.g. thin shaped steel sheet provided with nozzle elements with air distributors. Being static elements, the guide surfaces do not include wheels or wearing components, so the need of maintenance is mini­mal and operating reliability is good.
  • the heat com­pensation air necessary in a drying section is in fact partly blown through the nozzle elements on the guide surface to the surface of a web for more effective dry­ing. It is true that a structure of the invention re­quires operating power since the velocity of air coming from the nozzle elements must be supercritical during the threading of a tail end but a lower air velocity is sufficient during normal running. Also due to the struc­ture, the running of a web is all the time positively driven and thus there is no observable speed limit to restrict the operation or cause breaks.
  • the drying cylinders 1 of a paper making machine are mounted successively in the same plane. Therebetween are mounted rolls 2 which are necessary for the correct running of an endless drying wire 3.
  • the drying wire 3 is tensioned upon drying cylinders 1 and rolls 2 so as to press a web 5 tightly against the face of a drying cylinder.
  • the web running over a drying cylinder tends to stick to its face and to wind itself around the cylinder. This is prevented by using a blade 4 called a doctor blade which removes the web from a cylinder face and deflects the end of the web onto a guide surface OP.
  • the guide surf­ace OP is provided with nozzle elements 7 for blowing air in the running direction (arrow KS) of web 5.
  • the guide surface OP is designed for varying the running direction of a web as desired.
  • the general shape of guide surface OP is a U-shape as viewed from the side of a drying section. This shape can be obtained e.g. by using a profiled piece 6, made of thin steel sheet and comprising a floor portion 6a and side portions 6b joining the floor portion and extending from floor por­tion 6a toward drying cylinders 1.
  • the surface of pro­filed piece 6 facing the roll makes up a guide surface OP.
  • a profiled piece 6 making up said guide surface OP so as to comprise two separate elements 6′, 6 ⁇ whereby, when a break occurs and a web is torn to pieces, the space defined by roll 2 and guide surface OP can be cleaned through a gap 8 between elements 6′, 6 ⁇ .
  • the division of guide surface OP into two elements can be affected by designing the profiled piece so as to comprise elements that are substantially L-shaped as seen from the side of a drying section, said gap 8 between the elements being in alignment with the centre of roll 2 in the direction perpendicular to the straight line connecting the centres of drying cyl­inders 1.
  • Nozzle elements 7 can be transversal slice nozzles to which are connected transversal air distribution pipes 11 fitted outside said profiled piece 6. According to its design and size, said guide surface OP is provided with a necessary number of nozzles 7 having a combined effect so as to achieve the passage of web 5 based on coanda-effect from a drying cylinder preceding roll 2 to the next cylinder, so that the web is always spaced from drying wire 3.
  • One advantage gained by the invention is that a moving drying wire 3 induces air currents passing through dry­ing wire 3 and around roll 2. By taking advantage of these the passage of web 5 can be further stabilized at the guide surface.

Landscapes

  • Paper (AREA)
  • Drying Of Solid Materials (AREA)
EP19880121532 1987-12-23 1988-12-22 Trockenpartie einer Papiermaschine Withdrawn EP0321986A3 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI875690 1987-12-23
FI875690A FI78331C (fi) 1987-12-23 1987-12-23 Torkparti vid en pappersmaskin.

Publications (2)

Publication Number Publication Date
EP0321986A2 true EP0321986A2 (de) 1989-06-28
EP0321986A3 EP0321986A3 (de) 1991-04-17

Family

ID=8525613

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19880121532 Withdrawn EP0321986A3 (de) 1987-12-23 1988-12-22 Trockenpartie einer Papiermaschine

Country Status (2)

Country Link
EP (1) EP0321986A3 (de)
FI (1) FI78331C (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4012421A1 (de) * 1990-04-19 1991-10-24 Voith Gmbh J M Trockenpartie einer papiermaschine
EP0444316A3 (en) * 1990-02-22 1992-01-02 Valmet Paper Machinery Inc. Method and device in the cutting of the leader of a paper web

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FI130563B (en) * 2022-05-17 2023-11-21 Valmet Technologies Oy Method in a pulp dryer

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB870132A (en) * 1958-08-26 1961-06-14 Spooner Dryer & Eng Co Ltd Improvements in or relating to paper making machinery
DE1295993B (de) * 1965-05-10 1969-05-22 Kleinewefers Soehne J Dampfbefeuchtungseinrichtung fuer Warenbahnen, insbesondere fuer Papierbahnen
US3874997A (en) * 1973-03-21 1975-04-01 Valmet Oy Multiple cylinder drier in a paper machine
DE3132040A1 (de) * 1981-08-13 1983-03-03 J.M. Voith Gmbh, 7920 Heidenheim Trockenzylindergruppe

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0444316A3 (en) * 1990-02-22 1992-01-02 Valmet Paper Machinery Inc. Method and device in the cutting of the leader of a paper web
DE4012421A1 (de) * 1990-04-19 1991-10-24 Voith Gmbh J M Trockenpartie einer papiermaschine

Also Published As

Publication number Publication date
FI875690A0 (fi) 1987-12-23
FI78331C (fi) 1989-07-10
FI78331B (fi) 1989-03-31
EP0321986A3 (de) 1991-04-17

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