WO1992008003A1 - Procede de chauffage d'une bande de papier sur un cylindre exprimeur - Google Patents

Procede de chauffage d'une bande de papier sur un cylindre exprimeur Download PDF

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Publication number
WO1992008003A1
WO1992008003A1 PCT/US1991/007403 US9107403W WO9208003A1 WO 1992008003 A1 WO1992008003 A1 WO 1992008003A1 US 9107403 W US9107403 W US 9107403W WO 9208003 A1 WO9208003 A1 WO 9208003A1
Authority
WO
WIPO (PCT)
Prior art keywords
nip
roll
web
press
paper web
Prior art date
Application number
PCT/US1991/007403
Other languages
English (en)
Inventor
Jere W. Crouse
Original Assignee
Beloit 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 Beloit Corporation filed Critical Beloit Corporation
Publication of WO1992008003A1 publication Critical patent/WO1992008003A1/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
    • D21F3/0209—Wet presses with extended press nip
    • D21F3/0218—Shoe presses
    • 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
    • D21F3/0281—Wet presses in combination with a dryer roll
    • 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
    • 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

Definitions

  • the present invention relates to improvements in paperma ing machines, and more particularly to an improved press for dewatering a traveling paper web.
  • the web In a papermaking machine, the web is typically made from fibers in the former and passes immediately to the press section where a series of press nips are formed which mechanically press water from the web into traveling felts and thereafter passes to the dryer section where remaining water is evaporated from the web and the web thereafter having been formed and dried is wound on large rolls. It is well known that very substantial savings in the costs of manufacture of a web can be effected if more water is extracted in the press section by mechanical pressing in that the energy required for mechanical pressing for the removal of water is much less expensive than if the water is to be removed thermally.
  • the press nip In the pressing operation, it is essential that the press nip maintain uniform pressure across its width so that the paper web is dewatered uniformly.
  • One means of controlling the nip pressure is to use a controlled deflection roll which has a roll shell with a supporting shaft therein and lubricating or pressure means between the stationary shaft and the roll shell which is controllable to control the deflection and hence the nip pressure along the width of the nip. It has been discovered that by heating the lubricating or pressure fluid, the roll shell can be similarly heated to heat the roll shell and improve the dewatering operation in the press nip.
  • a still further object of the invention is to utilize the effect of heat of the moisture in a paper web to improve the mechanical dewatering in a press nip.
  • a still further object of the invention is to provide improved means for the transfer of heat to a traveling paper web in a press section to improve the dewatering effect and permit higher pressing speeds to be achieved.
  • a press nip is provided either formed between two press rolls or between a press roll and opposed pressing means such as a hydrodynamic shoe.
  • the press roll is heated to higher temperatures than heretofore thought possible by improving the heating effect of lubricating fluid directed into the interior of the- roll shell at higher temperatures than heretofore used.
  • the effective transfer of heat to the web is enhanced by longer residence time of contact between the wet web and the press roll shell. This is accomplished by a longer contact between the roll shell and web.
  • an extended nip press is used wherein the web is not merely passed between two rolls in a roll shell but between a roll and an extended nip press of the type having a hydrodynamic shoe.
  • the web is brought into contact with the press roll a substantial distance prior to the nip so that the web approaches the desired temperature even before entering the nip.
  • This feature is utilized in one form where two nips are used and the web is maintained in contact with the press roll between the first and second nip so that the temperature of the web is increased over that of the first nip when it reaches the second nip.
  • improved heat transfer can be accomplished by directing steam through the web prior to its entry into the nip.
  • the addition of steam directed against the web not only increases the temperature of the web but provides sufficient moisture at the location of contact between the surface of the web and the heated roll shell so that a more rapid temperature increase is experienced in the web from the heat of the roll shell.
  • FIG. 1 is a fragmentary side elevational view, taken partially in section, through a roll shell constructed and operating in accordance with the features of the present invention
  • FIG. 2 is an enlarged fragmentary vertical sectional view taken substantially along line II-II of Fig. 1;
  • FIG. 3 is an enlarged fragmentary sectional view illustrating a seal for a controlled deflection shoe for a press roll;
  • FIG. 4 is a schematic end elevational view of a press roll assembly constructed and operating in accordance with the features of the present invention
  • FIG. 5 is a schematic end elevational view of a modified form of the arrangement of Fig. 4;
  • FIG. 6 is another schematic end elevational view illustrating another form of practice of the invention.
  • FIG. 7 is a schematic end elevational view illustrating still another form of the invention.
  • Figs. 1, 2 and 3 illustrate features of construction of a press roll (8) of the type having a roll shell with a shoe controlled by pressurized liquid for controlling the pressure in the nip and for controlling the deflection of the roll.
  • a roll shell is shown with a support shoe 11 therein.
  • the shoe 11 is provided with pressure pockets 12 to be supplied hydraulic lubricating oil for lubricating the surface between the shoe 11 and the roll shell 10 and for applying a nip control force to the roll shell.
  • pressurized oil is delivered to a chamber 13 beneath a piston 14 supporting the shoe. Passages to the piston allow hydraulic oil to flow up to the pockets 12.
  • the piston is supported on a central shaft 9 which extends through the roll shell and is supported on framework.
  • Fig. 3 illustrates a modified form of seal for a piston 15 supported on a shaft 18.
  • a chamber 16 beneath the piston is supplied with pressurized oil, and the side of the piston is sealed by a sliding block 17 supported on a coil spring 17a which seals the block against the piston and thereby seals the pressure space 16 beneath the piston.
  • the lubricating oil which is delivered to support the piston and to feed oil to the pockets 12 and lubricate the shoe is heated to a relatively high temperature.
  • the press is intended to be operated at a temperature on the order of 400°F, that is, the web will be at 400°F in the press nip.
  • the lubricating fluid should be heated to a temperature at least 450°F to heat the roll shell and thereby heat the traveling paper web. It is contemplated that in certain runs, the lubricating oil may be heated substantially higher on the order of 750°F to 800°F.
  • An important concept of the invention is the improved heat transfer to the moisture of the web to improve press drying.
  • One concept is illustrated in Fig. 4 wherein an extended nip press is employed increasing the time of contact between the press roll and the web to increase the heat transfer between the roll shell and the web.
  • a web W is shown delivered to a press section which has a press roll shell 21 with an opposing press member 22.
  • the press member 22 has an extended hydrodynamic shoe 30 shaped to build a hydrodynamic layer of liquid in the nip.
  • Means (not shown) are employed to deliver a lubricating layer of hydrodynamic liquid to the nip.
  • a rubber belt 31 is driven through the nip supporting a web supporting felt 23.
  • the roll shell is internally supported by a stationary shaft 24 supported by a framework at its ends.
  • the shaft is provided with a hydraulic liquid supported piston 27 in a well 28 in the shaft.
  • the piston supports a shoe 25 having lubricating pockets 26 therein facing the inner surface of the roll shell.
  • the pockets are supplied with pressurized oil either through separate passages or through passages extending up through the piston 27 in a manner described in connection with Fig. 2.
  • An important feature of the invention is the delivery of a high temperature heated lubricant from a heated lubricant supply means 29.
  • the lubricant will be delivered to the internal of the roll shell in a temperature sufficient to reach 400°F of the web in the nip N.
  • the lubricant should be heated at least to 450° and higher temperatures are contemplated on the order of 700°F to 800°F.
  • a steam applicator 33 is positioned to receive the web as it enters the press.
  • the web at this point is supported by the felt 23 which is supported opposite the steam chamber 33 by a support 34.
  • Steam is directed down into the web to increase the temperature and increase the moisture at the surface.
  • the web is then carried on the felt 23 looped over felt roll 6 and around a roll 32 which brings the web into contact with the roll shell 21 and lays the web on the surface at a location substantially in advance of the nip end.
  • the web should be placed on the roll at least 30° in advance of the nip but a greater amount is possible depending on the type of paper being processed.
  • the contact between the web and the heated roll shell 21 for the amount of travel before it reaches the nip N substantially increases the temperature of the moisture in the web to enhance the pressing process.
  • an extended nip press such as shown in Fig. 4
  • the moisture in the web continues to be increased in temperature throughout the pressing operation thereby further enhancing the pressing of the water from the web into the felt 23.
  • the object is to bring the web being pressed up to at least 400°F temperature. Problems have been experienced in heating the web to lower temperatures between 200°F and 300°F. A number of web materials tend to soften and stick solidly to the roll shell at these lower temperatures so that the temperature of the web is a very critical problem. 400°F has been found to be a good starting range for high temperature pressing in that this temperature is above the softening type temperatures.
  • the prewrapping will bring the sheet temperature up past the 300°F mark, on the order of 350°F as the web enters the nip and heats further to reach the 400°F or over 400°F temperature.
  • Fig. 5 illustrates a press arrangement where a press roll shell 35 is employed and the opposing press member in this case is another press roll 36.
  • the web is presteamed by a steaming chamber 38 and the web is carried on a felt beneath the steaming shoe.
  • a roll 38a applies the web to the roll shell 35 prewrapping it so that heat transfer begins immediately and the web reaches the desired temperature by the time it reaches the nip N.
  • the roll shell is heated by an internal lubricating fluid supplied by a heater 39.
  • the internal support for the roll shell 35 is similar to that as shown in Fig. 4 and need not be described in detail.
  • Figs. 6 and 7 illustrate a modified form wherein increased heat transfer to the web is achieved by keeping the web wrapped on a press roll in a travel from a first nip N-l to a second nip N-2.
  • the first press N-l is a light pressure press which removes water but also insures that the web is in solid contact with the press roll shell
  • Nip pressures for the nip N-l on the order of 100 pli are acceptable, although a range of 100 to 200 pli may be employed.
  • a web W is formed on a forming wire 40 and transferred at the transfer roll 45 onto a felt 46.
  • the felt carries the web into the first nip N-l where it is pasted onto the outer surface of the heated roll shell.
  • the roll shell is internally supported on a stationary shaft 42. Controlled deflection of the roll shell for the first nip N-l is achieved by a shoe 44 within the roll shell and the shoe is supplied with heated pressurized oil from a heater 43.
  • the roll shell is supported opposite the second nip N-2 by a hydraulic shoe 44a which is supplied with heated pressurized oil from a heater 43a.
  • the heated oil will heat the roll shell on the order of 450°F.
  • the web is separated from the roll shell and passes down onto the first drum 49 of a dryer.
  • the water pressed from the web in the second nip is transferred to a felt 47 supported on a press roll 48.
  • the web is similarly carried on a roll shell 50 between two nips N-l and N-2.
  • a single felt lies outside of the web in its travel on the roll shell.
  • a web W is formed on a forming wire 57 and picked off the wire by the felt 55 with the felt being carried on a press roll 54.
  • the web travels from the first nip to the second nip N-2 where it is pressed by a press roll 55a transferring water to the felt 55.
  • the web is separated to pass down into the first roll 56 of a dryer section.
  • the web With the web traveling in contact with the roll shell for the distance between the two press nips, the web will approach the temperature of the roll shell by the time it hits the second nip. With the longer contact with the roll shell, the roll can be carried at 400°F to bring the web to that temperature.
  • Figs. 7 do not have the presteaming arrangement but that could be employed in this arrangement as well.
  • the presteaming By the presteaming, the speed of getting the sheet up to temperature is increased and steam is penetrated into the paper sheet as soon as possible. While moisture is added, it provides a deep penetration of the sheet.
  • the presteaming principally may be used without the prewrapping and in other arrangements, the prewrapping used without the presteaming. Depending upon the type of paper being used and the speed of operation, it is preferred that both be used to insure the desired temperature of the web in the press nip.
  • the typical dryness of the web coming into the press is on the order of 20% to 40%.
  • the dryness can approach in the range of 60% and sometimes as high as 75%.
  • the dryness decreases and with heavier weight paper, it becomes desirable to utilize a larger degree of prewrap to get the temperature of the sheet to the desired degree by the time the sheet enters the press nip. All of this is accomplished by heating the lubricant within the roll shell to maintain the roll shell at a good heat transfer temperature. There, of course, will be some heat loss going through the shell since there is a substantial heat transfer to the moisture of the web.

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  • Paper (AREA)

Abstract

Procédé et appareil permettant d'exprimer l'eau d'une bande de papier (B) se déplaçant dans une machine servant à fabriquer du papier, dans lequel la bande (B) passe par un rouleau exprimeur (R) comprenant un bandage de cylindre creux (10, 21, 35) pourvu d'un système de commande de déviation (11, 27) situé à l'intérieur et dans lequel on chauffe le bandage de cylindre en faisant passer un lubrifiant dans ledit bandage de cylindre, en plaçant la bande contre le bandage de cylindre à une certaine distance du rouleau exprimeur et dans une forme d'exécution, en vaporisant de la vapeur (33, 38) sur la bande avant de l'introduire dans le rouleau exprimeur. Dans une autre forme d'exécution, deux rouleaux exprimeurs (N-1, N-2) sont associés au même bandage de cylindre (41, 50) et la bande est maintenue sur le cylindre (8) entre les deux rouleaux exprimeurs devant être chauffés afin de faciliter le transfert d'eau provenant de la bande jusqu'à un feutre de transport (46, 55) situé dans le rouleau exprimeur.
PCT/US1991/007403 1990-10-31 1991-10-07 Procede de chauffage d'une bande de papier sur un cylindre exprimeur WO1992008003A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US60741590A 1990-10-31 1990-10-31
US607,415 1990-10-31

Publications (1)

Publication Number Publication Date
WO1992008003A1 true WO1992008003A1 (fr) 1992-05-14

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1995021962A1 (fr) * 1994-02-14 1995-08-17 Beloit Technologies, Inc. Appareil de pressage a haute temperature et a poids eleve
WO1997016593A1 (fr) * 1995-11-02 1997-05-09 Beloit Technologies, Inc. Train de sechage par pressage force et chauffage pour papier mousseline
WO2014137274A1 (fr) * 2013-03-04 2014-09-12 Valmet Aktiebolag Agencement et procédé pour déshydrater un tissu fibreux en un contenu solide à teneur très sèche

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE681897C (de) * 1937-03-06 1939-10-04 Karl Franz Krenn Presse zum Entwaessern von Zellstoff- und Papierbahnen
US3560333A (en) * 1967-08-15 1971-02-02 Scott Paper Co Method and apparatus for drying paper on a yankee dryer
US3861997A (en) * 1972-12-21 1975-01-21 Beloit Corp Paper machine press arrangement with stacked press rolls
EP0224428A1 (fr) * 1985-11-25 1987-06-03 Beloit Corporation Presse à patin enfermée
EP0289477A2 (fr) * 1987-04-28 1988-11-02 Valmet Paper Machinery Inc. Procédé pour le pressage à chaud d'une bande de papier et dispositif de séchage pour l'application du procédé
WO1989009690A1 (fr) * 1988-04-13 1989-10-19 Miller Ray R Cylindre a flux thermique eleve et presse le mettant en oeuvre
EP0401190A2 (fr) * 1989-05-30 1990-12-05 Valmet Paper Machinery Inc. Section de presse d'une machine à papier ou carton
WO1991008339A1 (fr) * 1989-11-27 1991-06-13 Beloit Corporation Dispositif de presse par section

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE681897C (de) * 1937-03-06 1939-10-04 Karl Franz Krenn Presse zum Entwaessern von Zellstoff- und Papierbahnen
US3560333A (en) * 1967-08-15 1971-02-02 Scott Paper Co Method and apparatus for drying paper on a yankee dryer
US3861997A (en) * 1972-12-21 1975-01-21 Beloit Corp Paper machine press arrangement with stacked press rolls
EP0224428A1 (fr) * 1985-11-25 1987-06-03 Beloit Corporation Presse à patin enfermée
EP0289477A2 (fr) * 1987-04-28 1988-11-02 Valmet Paper Machinery Inc. Procédé pour le pressage à chaud d'une bande de papier et dispositif de séchage pour l'application du procédé
WO1989009690A1 (fr) * 1988-04-13 1989-10-19 Miller Ray R Cylindre a flux thermique eleve et presse le mettant en oeuvre
EP0401190A2 (fr) * 1989-05-30 1990-12-05 Valmet Paper Machinery Inc. Section de presse d'une machine à papier ou carton
WO1991008339A1 (fr) * 1989-11-27 1991-06-13 Beloit Corporation Dispositif de presse par section

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1995021962A1 (fr) * 1994-02-14 1995-08-17 Beloit Technologies, Inc. Appareil de pressage a haute temperature et a poids eleve
WO1997016593A1 (fr) * 1995-11-02 1997-05-09 Beloit Technologies, Inc. Train de sechage par pressage force et chauffage pour papier mousseline
WO2014137274A1 (fr) * 2013-03-04 2014-09-12 Valmet Aktiebolag Agencement et procédé pour déshydrater un tissu fibreux en un contenu solide à teneur très sèche

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