CA2308139C - Method and arrangement for drying a fiber web - Google Patents
Method and arrangement for drying a fiber web Download PDFInfo
- Publication number
- CA2308139C CA2308139C CA002308139A CA2308139A CA2308139C CA 2308139 C CA2308139 C CA 2308139C CA 002308139 A CA002308139 A CA 002308139A CA 2308139 A CA2308139 A CA 2308139A CA 2308139 C CA2308139 C CA 2308139C
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- Prior art keywords
- band
- fiber web
- wire
- drying
- turning rolls
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- 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
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- 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
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- 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)
- Multicomponent Fibers (AREA)
- Stringed Musical Instruments (AREA)
- Orthopedics, Nursing, And Contraception (AREA)
- Paper (AREA)
Abstract
The invention relates to a method and an arrangement for drying a fiber web, whereby the fiber web (5) is dried between two tight bands (1, 2) moving parallelly in the same direction and coming around turni ng rolls (6a, 6b, 7a, 7b). The first band (1) is heated by means of a pressure chamber (9) and the second band (2) is cooled by means of a water chamber (10). The fiber web (5) is led together with at least one felt or wire (3, 4) through a drying zone formed by the bands (1, 2) in such a way that the fiber web is in contact with the surface of the heated first band (1) and the felt or wire (3, 4) is between the fibe r web (5) and the cooled second band (2). The fiber web (5) is spread in its transverse direction before it is led into the drying apparatu s. A desired transverse tension on the fiber web (5) and a suitable stretched structure are then provided, which can be fixed to remain in the drying apparatus.
Description
METHOD AND ARRANGEMENT FOR DRYING A FIBER WEB
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.
The invention relates further to an arrangement for drying a fiber web, which arrangement comprises a drying apparatus comprising two end-less 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 be tween the bands in such a way that the fiber web is in contact with the heated frst band and the felt or wire, respectively, is between the fiber web and the cooled second band.
Drying a fiber web between two parallel metal bands moving in the same direction in such a way that the fiber web is in contact with the heated metal band and there is a wire between the fiber web and the second cooled metal band, so that the steam separated from the fiber web on account of heating condenses to the wire by the effect of the cold metal band, is known from several patent publications, of which can be mentioned e.g. Finnish Pat-ent Application 944 775 and U.S. Patent 4 461 095. The operation is based on that two endless metal bands are arranged to run around turning rolls and that pressure chambers containing hot steam and wafer, respectively, are provided against the inside surface of the loops formed by the bands so that the pres-sure produced presses the hot and the cold band, and respectively, the fiber web and the wire between them towards each other. The bands located be-tween 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.
In a conventional drying apparatus, where a fiber web is dried by means of several drying cylinders, the fiber web shrinks quite much in the transverse direction, which again weakens the transverse properties of the fi-ber web, such as compression resistance of a product to be manufactured.
Further in a conventional drying apparatus, the fiber web is subjected to a ma-chine direction tension, which is necessary for transporting the web. On ac-count of Poisson effect, this machine direction tE;nsion tends to make the web narrower still, which weakens the transverse properties of the web additionally.
In the drying apparatus described in the foregoing paragraph, where the fiber web is dried between two parallel metal bands moving in the same direction, it is possible to prevent the fiber web from shrinking during drying completely, both in the machine and transverse direction. The structure of the fiber web can then be fixed to remain such as it was when entering the drying appara-tus. In connection with some products, however, the transverse properties should be better still. As regards 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 present invention is directed towards the provision of a method and an arrangement, which can be utilized for improving the transverse properties of a fiber web.
In accordance with one aspect of the present invention, there is provided 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 2a heated first band and the felt or wire, respectively, is between the fiber web and the cooled second band, wherein the fiber web is spread in its transverse direction before it is led into the drying apparatus.
In accordance with a further aspect of the invention, there is provided 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, wherein 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 I 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 possi ble to improve the coefficient of elasticity, the tensile strength and the com pression 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 oppo-site to the spreader means without support at the spreader means or by sup-porting the fiber web with a veil-like wire stretching in the transverse direction, it is possible to spread the fiber web efficiently and easily.
The invention is described in greater detail in the attached draw-ings, where Figure 1 shows schematically a sectional side view taken in the travel direction of the web, illustrating an arrangement according to the inven-tion, Figure 2 shows schematically a sectional side view taken in the travel direction of the web, illustrating a second arrangement according to the invention, and Figure 3 shows schematically a detail of a third arrangement ac-cording to the invention at spreader rolls.
Figure 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. Corre-spondingly, 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 8b. 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 pre-venting liquid or gas from moving out of the space between the bands 1 and 2 sidewards, or vice versa. To effect vapor heating required by the drying, 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. At the edges of the water chamber 10, there are seals 10a, with which the second band 2 is sealed to the body 10b of the water chamber 10.
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. On account of the temperature of the first web 1, 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, in turn, is continuously cooled with water located below it, whereby the steam produced on the surface thereof con-denses 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. In connection with this application, 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. In addition to the spreader roll 11, 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. By using the drying appa-ratus 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 mat-ter content, because spreading a fiber web that is too dry may cause tearing of the fiber web 5.
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.
The invention relates further to an arrangement for drying a fiber web, which arrangement comprises a drying apparatus comprising two end-less 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 be tween the bands in such a way that the fiber web is in contact with the heated frst band and the felt or wire, respectively, is between the fiber web and the cooled second band.
Drying a fiber web between two parallel metal bands moving in the same direction in such a way that the fiber web is in contact with the heated metal band and there is a wire between the fiber web and the second cooled metal band, so that the steam separated from the fiber web on account of heating condenses to the wire by the effect of the cold metal band, is known from several patent publications, of which can be mentioned e.g. Finnish Pat-ent Application 944 775 and U.S. Patent 4 461 095. The operation is based on that two endless metal bands are arranged to run around turning rolls and that pressure chambers containing hot steam and wafer, respectively, are provided against the inside surface of the loops formed by the bands so that the pres-sure produced presses the hot and the cold band, and respectively, the fiber web and the wire between them towards each other. The bands located be-tween 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.
In a conventional drying apparatus, where a fiber web is dried by means of several drying cylinders, the fiber web shrinks quite much in the transverse direction, which again weakens the transverse properties of the fi-ber web, such as compression resistance of a product to be manufactured.
Further in a conventional drying apparatus, the fiber web is subjected to a ma-chine direction tension, which is necessary for transporting the web. On ac-count of Poisson effect, this machine direction tE;nsion tends to make the web narrower still, which weakens the transverse properties of the web additionally.
In the drying apparatus described in the foregoing paragraph, where the fiber web is dried between two parallel metal bands moving in the same direction, it is possible to prevent the fiber web from shrinking during drying completely, both in the machine and transverse direction. The structure of the fiber web can then be fixed to remain such as it was when entering the drying appara-tus. In connection with some products, however, the transverse properties should be better still. As regards 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 present invention is directed towards the provision of a method and an arrangement, which can be utilized for improving the transverse properties of a fiber web.
In accordance with one aspect of the present invention, there is provided 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 2a heated first band and the felt or wire, respectively, is between the fiber web and the cooled second band, wherein the fiber web is spread in its transverse direction before it is led into the drying apparatus.
In accordance with a further aspect of the invention, there is provided 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, wherein 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 I 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 possi ble to improve the coefficient of elasticity, the tensile strength and the com pression 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 oppo-site to the spreader means without support at the spreader means or by sup-porting the fiber web with a veil-like wire stretching in the transverse direction, it is possible to spread the fiber web efficiently and easily.
The invention is described in greater detail in the attached draw-ings, where Figure 1 shows schematically a sectional side view taken in the travel direction of the web, illustrating an arrangement according to the inven-tion, Figure 2 shows schematically a sectional side view taken in the travel direction of the web, illustrating a second arrangement according to the invention, and Figure 3 shows schematically a detail of a third arrangement ac-cording to the invention at spreader rolls.
Figure 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. Corre-spondingly, 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 8b. 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 pre-venting liquid or gas from moving out of the space between the bands 1 and 2 sidewards, or vice versa. To effect vapor heating required by the drying, 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. At the edges of the water chamber 10, there are seals 10a, with which the second band 2 is sealed to the body 10b of the water chamber 10.
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. On account of the temperature of the first web 1, 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, in turn, is continuously cooled with water located below it, whereby the steam produced on the surface thereof con-denses 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. In connection with this application, 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. In addition to the spreader roll 11, 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. By using the drying appa-ratus 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 mat-ter content, because spreading a fiber web that is too dry may cause tearing of the fiber web 5.
5 Figure 2 shows a schematic sectional side view taken in the travel direction of the web, illustrating a second arrangement according to the inven-tion. 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 ac-cording to the invention at spreader rolls 11. Reference numerals of Figure 3 correspond to those of the Figures 1 and 2. By means of guiding rolls 8, 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. On the other hand, such an unsupported section may be inconvenient in some cases, and there-fore, a veil-like auxiliary wire 12 elastic in the transverse direction, but essen-tially inextensible in the machine direction, may be arranged for supporting the fiber web 5. Using such an auxiliary wire 12 also facilitates the spreading, but the auxiliary wire 12 simultaneously supports the fiber web 5 in the machine direction. Naturally, the wire 3 may also be a veil-like wire, elastic in the trans-verse 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.
More spreading force may be required of the spreading means for a fiber web 5 of thicker paper and board qualities, in particular. Accordingly, Fig ure 3 shows that three spreader rolls 11 are used as spreading means. If de sired, the number of the spreader rolls 11 may be even higher. In case of Fig ure 3, the spreader rolls 11 are arranged at the same level in the height direc tion, 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. In case of Figure 3, the height level of the midmost spreader roll 11 is preferably adjustable. By ad-justing the height level of said spreader roll 11, it is possible to adjust the en-folding of the web 5 and the auxiliary wire 12 around the spreader rolls 11.
When the process of threading the fiber web 5 is started, the midmost spreader roll 11 may be lifted above the normal upper edge of the fcber web 5, which makes the threading of the fiber web 5 easy.
The drawings and the description relating to them are only intended to illustrate the idea of the invention. As to the details, the invention may vary within the scope of the claims. So, it is not essential which pressure medium is used in the pressure chamber 9 and the water chamber 10. The medium of the pressure chamber 9 may thus be steam, air or hot combustion gases of fuel, or, for instance, water. In addition to water, e.g. air can also be used as pressure medium in the water chamber 10.
In addition to the heating caused by the pressure chamber 9, 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 pres-sure chamber 9 or drying the fiber web 5 may take place even without a pres-sure chamber 9.
Moreover, 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.
Figure 3 shows a side view of a detail of a third arrangement ac-cording to the invention at spreader rolls 11. Reference numerals of Figure 3 correspond to those of the Figures 1 and 2. By means of guiding rolls 8, 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. On the other hand, such an unsupported section may be inconvenient in some cases, and there-fore, a veil-like auxiliary wire 12 elastic in the transverse direction, but essen-tially inextensible in the machine direction, may be arranged for supporting the fiber web 5. Using such an auxiliary wire 12 also facilitates the spreading, but the auxiliary wire 12 simultaneously supports the fiber web 5 in the machine direction. Naturally, the wire 3 may also be a veil-like wire, elastic in the trans-verse 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.
More spreading force may be required of the spreading means for a fiber web 5 of thicker paper and board qualities, in particular. Accordingly, Fig ure 3 shows that three spreader rolls 11 are used as spreading means. If de sired, the number of the spreader rolls 11 may be even higher. In case of Fig ure 3, the spreader rolls 11 are arranged at the same level in the height direc tion, 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. In case of Figure 3, the height level of the midmost spreader roll 11 is preferably adjustable. By ad-justing the height level of said spreader roll 11, it is possible to adjust the en-folding of the web 5 and the auxiliary wire 12 around the spreader rolls 11.
When the process of threading the fiber web 5 is started, the midmost spreader roll 11 may be lifted above the normal upper edge of the fcber web 5, which makes the threading of the fiber web 5 easy.
The drawings and the description relating to them are only intended to illustrate the idea of the invention. As to the details, the invention may vary within the scope of the claims. So, it is not essential which pressure medium is used in the pressure chamber 9 and the water chamber 10. The medium of the pressure chamber 9 may thus be steam, air or hot combustion gases of fuel, or, for instance, water. In addition to water, e.g. air can also be used as pressure medium in the water chamber 10.
In addition to the heating caused by the pressure chamber 9, 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 pres-sure chamber 9 or drying the fiber web 5 may take place even without a pres-sure chamber 9.
Moreover, 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.
Claims (12)
1. 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, wherein the fiber web is spread in its transverse direction before it is led into the drying apparatus.
2. A method according to claim 1, wherein during spreading, the fiber web is essentially unsupported by the wires.
3. A method according to claim 1 or 2, wherein during spreading, the fiber web is supported in the transverse direction by an elastic wire.
4. A method according to any one of claims 1 to 3, wherein the first band is heated by means of a pressure chamber and the second band is cooled by means of a chamber containing pressurized medium.
5. 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, wherein the arrangement comprises means for spreading the fiber web in its transverse direction before it is led into the drying apparatus.
6. An arrangement according to claim 5, wherein the means for spreading the fiber web comprise at least one spreader roll.
7. An arrangement according to claim 6, wherein the means for spreading the fiber web comprise at least two spreader rolls.
8. An arrangement according to claim 6 or 7, wherein the height level of at least one spreader roll is adjustable.
9. An arrangement according to any one of claims 5 to 8, wherein the wires are arranged by means of guide rolls in such a way that, at the spreading means, the fiber web is essentially unsupported by the wires.
10. An arrangement according to any one of claims 5 to 9, wherein a wire elastic in the transverse direction is arranged to support the fiber web at the spreading means.
11. An arrangement according to claim 10, wherein the wire elastic in the transverse direction is an auxiliary wire.
12. An arrangement according to any one of claims 5 to 11, wherein the drying apparatus comprises a pressure chamber .arranged to heat the first band and a chamber containing a pressurized medium and arranged to cool the second band.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FI971210 | 1997-03-21 | ||
| FI971210A FI101897B (en) | 1997-03-21 | 1997-03-21 | Method and apparatus for drying a fiber web |
| PCT/FI1998/000240 WO1998042913A1 (en) | 1997-03-21 | 1998-03-19 | Method and arrangement for drying a fiber web |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2308139A1 CA2308139A1 (en) | 1998-10-01 |
| CA2308139C true CA2308139C (en) | 2005-05-24 |
Family
ID=8548443
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002308139A Expired - Fee Related CA2308139C (en) | 1997-03-21 | 1998-03-19 | Method and arrangement for drying a fiber web |
Country Status (9)
| Country | Link |
|---|---|
| EP (1) | EP1009875B1 (en) |
| JP (1) | JP2001516405A (en) |
| KR (1) | KR20010005532A (en) |
| AT (1) | ATE226268T1 (en) |
| AU (1) | AU6501098A (en) |
| CA (1) | CA2308139C (en) |
| DE (1) | DE69808786T2 (en) |
| FI (1) | FI101897B (en) |
| WO (1) | WO1998042913A1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102004017818A1 (en) | 2004-04-13 | 2005-11-03 | Voith Paper Patent Gmbh | dry arrangement |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FI96790C (en) * | 1994-10-11 | 1996-08-26 | Tampella Oy Valmet | Device for drying and smoothing the fibrous web |
-
1997
- 1997-03-21 FI FI971210A patent/FI101897B/en not_active IP Right Cessation
-
1998
- 1998-03-19 KR KR1019997008591A patent/KR20010005532A/en not_active Application Discontinuation
- 1998-03-19 DE DE69808786T patent/DE69808786T2/en not_active Expired - Fee Related
- 1998-03-19 CA CA002308139A patent/CA2308139C/en not_active Expired - Fee Related
- 1998-03-19 EP EP98910753A patent/EP1009875B1/en not_active Expired - Lifetime
- 1998-03-19 AU AU65010/98A patent/AU6501098A/en not_active Abandoned
- 1998-03-19 WO PCT/FI1998/000240 patent/WO1998042913A1/en not_active Application Discontinuation
- 1998-03-19 AT AT98910753T patent/ATE226268T1/en not_active IP Right Cessation
- 1998-03-19 JP JP54092498A patent/JP2001516405A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| JP2001516405A (en) | 2001-09-25 |
| CA2308139A1 (en) | 1998-10-01 |
| FI101897B1 (en) | 1998-09-15 |
| AU6501098A (en) | 1998-10-20 |
| DE69808786D1 (en) | 2002-11-21 |
| EP1009875B1 (en) | 2002-10-16 |
| FI971210A0 (en) | 1997-03-21 |
| KR20010005532A (en) | 2001-01-15 |
| DE69808786T2 (en) | 2003-06-26 |
| EP1009875A1 (en) | 2000-06-21 |
| FI101897B (en) | 1998-09-15 |
| WO1998042913A1 (en) | 1998-10-01 |
| ATE226268T1 (en) | 2002-11-15 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |