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
  • D21F5/004—Drying webs by contact with heated surfaces or materials
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F26—DRYING
  • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
  • F26B13/00—Machines and apparatus for drying fabrics, fibres, yarns, or other materials in long lengths, with progressive movement
  • F26B13/10—Arrangements for feeding, heating or supporting materials; Controlling movement, tension or position of materials
  • F26B13/105—Drying webs by contact with heated surfaces other than rollers or drums

Definitions

• the invention relates to a method for drying a fiber web, in which method the fiber web is dried with a drying apparatus comprising two endless air-impermeable bands, first turning rolls, the first band being arranged to turn around the first turning rolls, and second turning rolls, the second band being arranged to turn around the second turning rolls, whereby the first band and the second band are arranged to run part of the way parallel with each other in such a way that they form a drying zone between them, the first band being heated and the second band being cooled, and whereby the fiber web and at least one felt or wire are led between the bands in such a way that the fiber web is in contact with the heated first band and the felt or wire, respectively, is between the fiber web and the cooled second band.
• a drying apparatus comprising two endless air-impermeable bands, first turning rolls, the first band being arranged to turn around the first turning rolls, and second turning rolls, the second band being arranged to turn around the second turning rolls, whereby the first band and the second band are arranged to run part of the
• the invention relates further to an arrangement for drying a fiber web, which arrangement comprises a drying apparatus comprising two endless air-impermeable bands, first turning rolls, the first band being arranged to turn around the first turning rolls, and second turning rolls, the second band being arranged to turn around the second turning rolls, whereby the first band and the second band are arranged to run part of the way parallel with each other in such a way that they form a drying zone between them, the first band being heated by heating means and the second band being cooled by cooling means, and whereby the fiber web and at least one felt or wire are led between the bands in such a way that the fiber web is in contact with the heated first band and the felt or wire, respectively, is between the fiber web and the cooled second band.
• a drying apparatus comprising two endless air-impermeable bands, first turning rolls, the first band being arranged to turn around the first turning rolls, and second turning rolls, the second band being arranged to turn around the second turning rolls, whereby the first band and the second band are arranged to run part of the
• the bands located between the pressure chambers constitute by means of seals one side of the pressure chambers so that the steam and water can affect the bands directly.
• the operation of the apparatus is fully known per se and disclosed e.g. in the above patent applications, which are incorporated herein by reference.
• the structure of the fiber web can then be fixed to remain such as it was when entering the drying apparatus.
• the transverse properties should be better still.
• packing boards in particular, where the transverse direction usually is the vertical direction of a board package as well, the transverse properties of the fiber web shall also be very good. Especially when packages are piled on each other, the vertical compression strength of the packages will be critical.
• the object of the present invention is to provide a method and an arrangement, which can be utilized for improving the transverse properties of a fiber web.
• the method of the invention is characterized in that the fiber web is spread in its transverse direction before it is led into the drying apparatus. Further, the arrangement of the invention is characterized in that the arrangement comprises means for spreading the fiber web in its transverse direction before it is led into the drying apparatus.
• the essential idea of the invention is that a fiber web is spread in its transverse direction before it is led into a drying apparatus. Moreover, it is es- sential that, after spreading, the fiber web is dried between two parallel bands moving in the same direction in such a way that the fiber web is in contact with the heated band and there is a wire between the fiber web and the second cooled band, so that the steam separated from the fiber web on account of heating condenses to the wire by the effect of the cold band. Further, the idea of a preferred embodiment is that the fiber web is spread by means of at least one spreader roll. The idea of still another preferred embodiment is that, while the fiber web is spread, the side of the fiber web which is opposite to the spreader means is not supported or as a support is used a veil-like wire elastic in the transverse direction.
• An advantage of the invention is that by spreading the fiber web in the transverse direction before leading it into the drying apparatus, it is possible to improve the coefficient of elasticity, the tensile strength and the compression resistance of the fiber web in the transverse direction. Further, by using a heated and a cooled band moving in the same direction for drying after the spreading, it is possible to fix the structure provided by a spreader means to remain in the fiber web. By leaving that side of the fiber web which is opposite to the spreader means without support at the spreader means or by supporting the fiber web with a veil-like wire stretching in the transverse direction, it is possible to spread the fiber web efficiently and easily.
• Figure 1 shows schematically a sectional side view taken in the travel direction of the web, illustrating an arrangement according to the invention
• Figure 2 shows schematically a sectional side view taken in the travel direction of the web, illustrating a second arrangement according to the invention
• Figure 3 shows schematically a detail of a third arrangement according to the invention at spreader rolls.
• FIG. 1 is a schematic sectional side view taken in the travel direc- tion of the a web, illustrating an arrangement according to the invention.
• the arrangement comprises a drying apparatus comprising endless air- impermeable bands that conduct heat well and are preferably made of metal: viz. a first band 1 , i.e. the upper band, and a second band 2, i.e. the lower band, a fine wire or felt 3, a coarse wire 4 and fiber web 5 running between those surfaces of the bands that face each other.
• the fiber web 5 moves in the direction indicated by arrow A.
• the first band 1 is arranged to turn around first turning rolls 6a and 6b located at the ends of the drying apparatus.
• the second band 2 is arranged to turn around second turning rolls 7a and 7b also located at the ends of the drying apparatus, below the first turning rolls 6a and 6b.
• the wires 3 and 4 are supported and guided by means of guide rolls 8. Since the pressure prevailing in the drying zone in the space between the bands 1 and 2 is usually different from the pressure prevailing outside or on the sides of the bands 1 and 2, seals are provided on both sides of the apparatus between or at the edges of the bands 1 and 2, the seals preventing liquid or gas from moving out of the space between the bands 1 and 2 sidewards, or vice versa.
• the drying apparatus comprises a pressure chamber 9, which is located above the first band 1.
• the first band 1 is sealed with seals 9a to the body 9b of the pressure chamber so that the steam in the pressure chamber 9 is maintained at a suitable pressure.
• Below the second band 2 there is a water chamber 10 containing water that cools the second band 2.
• the operation of the drying apparatus is based on heating the first band 1 being in contact with the web 5 by hot steam contained in the pressure chamber 9.
• the water in the web 5 is then vaporized and transferred through the wires 3 and 4 toward the second band 2.
• the second band is continuously cooled with water located below it, whereby the steam produced on the surface thereof condenses into water and is removed with the band 2 and the wire 4.
• the arrangement comprises further a spreader roll 11 , by which the fiber web 5 is spread in its transverse direction before it is led into the drying apparatus.
• the term 'transverse' signifies a direction of the fiber web 5 essentially vertical to the machine direction.
• the spreader roll 11 is a rotating curved roll, by which the fiber web 5 can be spread in its transverse direction.
• the spreading means may be a curved slide rod or mechanical spreading means at the edge of the fiber web 5 or some other spreading means known per se, for instance.
• the spreading means is preferably positioned as close to the drying apparatus as possible, whereby the transverse stretching of the fiber web 5 can be preserved as efficiently as possible.
• the drying apparatus of Figure 1 it is possible to fix a desired transverse tension and a suit- able stretched structure to remain in the fiber web 5.
• the spreading of the fiber web 5 is preferably subjected to a fiber web having a lowest possible dry matter content, because spreading a fiber web that is too dry may cause tearing of the fiber web 5.
• Figure 2 shows a schematic sectional side view taken in the travel direction of the web, illustrating a second arrangement according to the invention.
• the arrangement of Figure 2 corresponds to the arrangement of Figure 1 , except that the arrangement of Figure 2 comprises a spreader roll 11 arranged below the wire 3.
• Figure 3 shows a side view of a detail of a third arrangement according to the invention at spreader rolls 11. Reference numerals of Figure 3 correspond to those of the Figures 1 and 2.
• the wire 3 is led away from supporting the fiber web 5 at the spreader rolls 11. The fiber web 5 can then be spread very easily and efficiently.
• a veil-like auxiliary wire 12 elastic in the transverse direction, but essentially inextensible in the machine direction may be arranged for supporting the fiber web 5.
• auxiliary wire 12 also facilitates the spreading, but the auxiliary wire 12 simultaneously supports the fiber web 5 in the machine direction.
• the wire 3 may also be a veil-like wire, elastic in the transverse direction, but essentially inextensible in the machine direction, in which case it is not necessary to lead the wire away from supporting the fiber web at the spreader rolls 11 like in Figure 3.
• FIG. 3 shows that three spreader rolls 11 are used as spreading means. If desired, the number of the spreader rolls 11 may be even higher.
• the spreader rolls 11 are arranged at the same level in the height direction, whereby enfolding the fiber web 5 and the auxiliary wire 12 around each spreader roll 11 can be made relatively long. It is preferable to provide at least one spreader roll 11 with adjustable height level.
• the height level of the midmost spreader roll 11 is preferably adjustable. By adjusting the height level of said spreader roll 11 , it is possible to adjust the enfolding of the web 5 and the auxiliary wire 12 around the spreader rolls 11.
• the midmost spreader roll 11 may be lifted above the normal upper edge of the fiber web 5, which makes the threading of the fiber web 5 easy.
• the medium of the pressure chamber 9 may thus be steam, air or hot combustion gases of fuel, or, for instance, water.
• water e.g. air can also be used as pressure medium in the water chamber 10.
• the first band 1 can also be heated at other places in manners fully known per se. Further, heating the first band 1 may take place also entirely outside the pressure chamber 9 or drying the fiber web 5 may take place even without a pressure chamber 9.
• the second band 2 can be cooled also outside the water chamber 10 or the cooling can even be performed without a water chamber 10 in manners fully known per se.

Landscapes

• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Treatment Of Fiber Materials (AREA)
• Drying Of Solid Materials (AREA)
• Paper (AREA)
• Multicomponent Fibers (AREA)
• Stringed Musical Instruments (AREA)
• Orthopedics, Nursing, And Contraception (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=8548443

Family Applications (1)

Country Status (9)

Families Citing this family (1)

Family Cites Families (1)

• 1997
  • 1997-03-21 FI FI971210A patent/FI101897B1/fi not_active IP Right Cessation
• 1998
  • 1998-03-19 AT AT98910753T patent/ATE226268T1/de not_active IP Right Cessation
  • 1998-03-19 EP EP98910753A patent/EP1009875B1/fr not_active Expired - Lifetime
  • 1998-03-19 DE DE69808786T patent/DE69808786T2/de not_active Expired - Fee Related
  • 1998-03-19 CA CA002308139A patent/CA2308139C/fr not_active Expired - Fee Related
  • 1998-03-19 AU AU65010/98A patent/AU6501098A/en not_active Abandoned
  • 1998-03-19 JP JP54092498A patent/JP2001516405A/ja active Pending
  • 1998-03-19 KR KR1019997008591A patent/KR20010005532A/ko not_active Application Discontinuation
  • 1998-03-19 WO PCT/FI1998/000240 patent/WO1998042913A1/fr not_active Application Discontinuation

Non-Patent Citations (1)

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