Valmet Paper Machinery Inc.

Valmet Corporation

Heikki Ilvespaa

Antti Kuhasalo

Reima Kerttula

Allan Liedes

Olavi Viitanen

Seppo Elijoki

Antti I Ilmarinen

Pertti Heikkila

Jouko Yli-Kauppila

Mikko Karvinen

Pekka Taskinen

Matti Korpela

Dick Parker

Henrik Petterson

Jorma Laapotti

Kari Holopainen

Juha Kaihovirta

Petri Nyberg

Jyrki Jaakkola

Vaino Sailas

Ari Linsuri

Lauri Verkasalo

Ilkka Jokioinen

Erkki Partanen

Va/ Ino/ Sailas

Iikka Jokioinen

A method for producing surface-treated paper, in particular of fine paper, and a dry end of a paper machine that makes use of the method. A paper web that has been dewatered by pressing is dried in the forward dryer section, in which drying energy is applied to the paper web over the entire length of the forward dryer section asymmetrically in the z-direction from the side of the bottom face of the web. This step is carried out by a number of successive groups with single-wire draw that are open downward. In this manner, shrinkage of the web both in the machine direction and in the cross direction is reduced or at least partially prevented, which shrinkage tends to take place when the dry solids content becomes higher. Paper broke is removed from underneath the drying groups that are open downward substantially by the force of gravity onto the broke conveyor placed underneath. The paper web which has a tendency of curling because of the asymmetric forward-drying is passed to the finishing section where it is finished while it is moistened and/or worked plastically so that the tendencies of curling that arose in the web in the forward drying stage are substantially reduced.

Method for producing surface-treated paper

Dry end of a paper machine

A method and device for enhancing the run of a web in a paper machine in which water is removed from the web by pressing the web in at least one press nip and after pressing, the web is dried in at least one dryer group applying impingement drying. The web is guided along a substantially linear path or by using a large curve radius in the dryer group applying impingement drying. In the drying stage, after the impingement drying, the web is dried in at least one dryer group having normal single-wire draw. The web is passed from the pressing stage to the drying stage as a closed draw and more particularly, from the pressing stage to the area with single-wire draw in the drying stage so that the web is constantly supported against at least one support face.

Method and device for enhancing the run of a paper web in a paper machine

A device for threading a paper web from a dryer section to a finishing device situated after the dryer section in the running direction of the web including a rope threading arrangement. A leader strip is separated from the edge of the paper web in the dryer section and the leader strip is directed between a pair of ropes included in the rope threading arrangement. The leader strip is carried to the finishing device on support of the ropes. To effect the transfer of the leader strip from the drying wire to the rope, at the inlet side of the last drying cylinder in the dryer section, a rope gap is formed out of the ropes and the leader strip, which is supported by the drying wire thereat, is transferred by an air blowing into the rope gap. The leader strip is passed by the ropes over the last drying cylinder to the finishing device.

Device for threading a paper web

Method for producing surface-treated paper and dry end of a paper machine

A method and device for drying a paper web wherein the paper web is supported on a drying wire without long open draws of the web. The paper web is contact-dried by pressing it with the drying wire onto a face of a contact-drying cylinder whose diameter is greater than about 1.5 m on a sector b whose magnitude is greater than about 180.degree.. The web is evaporation-dried as blowing-on drying and/or as through-drying by means of high-velocity drying-gas jets applied to the web on the drying wire on the face of the following large-diameter cylinder whose diameter is greater than about 2 m on a sector a having a magnitude greater than about 180.degree. while the web is on the side of the outside curve. The web to be dried is passed over a sector c of the suction roll which is subjected to negative pressure while the web is supported on the drying wire at the side of the outside curve. The magnitude of the sector of the suction roll has a magnitude greater than about 160.degree. and the diameter of the suction roll is less than the diameter of the contact-drying cylinder.

Drying method and drying module as well as dryer sections that make use

A hybrid former in a paper machine including a lower-wire loop in which there is an initial single-wire portion of a forming zone. In this initial portion, there are draining elements inside the lower-wire loop and thereafter wire-guide and draining elements. The former includes an upper-wire unit in which an upper wire is guided by guide rolls and by a breast roll onto a pulp layer formed on the single-wire portion of the lower wire. In a subsequent twin-wire portion following the single-wire portion, there is a draining and forming unit which includes at least one pressure-loaded press unit and at least one draining-chamber and support unit, which units are arranged inside opposite wire loops. In the units, there are sets of ribs which are pressure-loaded against each other. At the beginning of the twin-wire portion, inside the lower-wire loop, there is a revolving guide and forming roll which is in tangential contact with the lower wire or curves the twin-wire portion at a small angle which is in a range from about 0.degree. to about 5.degree.. The guide and forming roll is substantially immediately followed by the draining and forming unit which includes the sets of ribs. In the area of the draining and forming unit, water is drained primarily through the upper wire while aided by the negative pressures in the draining chamber or chambers in the unit.

Hybrid former with an MB unit in a paper machine

Drying module and dryer sections that make use of same, in particular

The invention is related to a method and a device in the drying section of a paper machine for reducing the tendency of the paper to curl. The paper web is dried on drying cylinders, against whose heated faces the paper web is pressed by means of a drying wire. In the drying section, groups of drying cylinders are used, in which twin-wire draw and/or single-wire draw is/are applied. In the drying section, hot water steam is fed substantially onto the entire width of the paper web, by means of which steam tensions that have been formed or that tend to be formed in the fiber mesh in the paper web are relaxed by means of heat and moisture in the area of their formation or substantially immediately thereafter. Moreover, the transverse curling profile and/or moisture profile of the paper web can be controlled by the steam treatment.

Method and apparatus for reduction of curling of paper in the drying

The present invention relates to a method and device in the draw of a paper web for reduction and equalization of transverse shrinkage of the paper web in the drying section of a paper machine. The lateral areas of the wire running in conjunction with the paper web are provided with a coating adhesion means, whereby, by means of the coating adhesion means, at the drying stage an adhesion force is produced between the lateral areas of the wire and of the paper to prevent transverse shrinkage of the paper web.

Method and device for reduction and equalization of transverse shrinkage

A method in a drying group or groups provided with a single-wire draw in a multi-cylinder dryer of a paper machine in the draw of a web. The multi-cylinder dryer comprises drying cylinders heated by means of steam or equivalent, with the web being pressed by a drying wire against the cylinder faces of these drying cylinders. The multi-cylinder dryer has leading or lower cylinders on which the web runs outside the drying wire which is, for example, a felt. The leading cylinders or rolls are provided with holes passing through a mantle of the leading cylinders or rolls, these holes being fitted to open into an inner space of negative pressure within the leading cylinder or roll and to open, at an opposite end, into grooves provided on a mantle face of the rolls. The negative pressure inside the roll is arranged to be transmitted to the grooves provided on the outer face of the roll mantle, so that an adhesion force is applied to the web through the grooves. In the method, a negative pressure is applied to the entire inside mantle of the roll, and free flow of air is permitted through the holes from an area above the cylinder and into the interior space within the cylinder. The present invention further concerns a device for use in the single-wire draw of the multi-cylinder dryer of the paper machine, and also to a paper-machine cylinder itself.

Method and device for drawing a web through a group of drying cylinders

The invention relates to an apparatus for use in the drying section of a paper machine, which apparatus comprises a drying cylinder group formed by drying cylinders and a roll group formed by rolls, preferably suction rolls located at a different height relative to the drying cylinders. The geometric rotational axis of the roll located in an area between two adjacent drying cylinders in a different height position is spaced away from the center plane between the center axes of the drying cylinders. The surface of the roll, preferably a suction roll, is adapted to be located as close to the surface of the drying cylinder on the web outgoing side of the roll as possible, whereby the free transfer distance of the outgoing side is minimized.

Drying section apparatus for a paper making machine

The invention relates to a suction roll (10) comprising a turbulence suppression element (16) located in the vicinity of the end of an external suction pipe (15). The turbulence suppression element (16) comprises at least one sheet member and is fitted relative to the end of the suction pipe (15) in such a way that turbulence in the intake air during the suction phase is substantially prevented and that a low air pressure is thus maintained at a desired, approximately constant value on the inner surface of the roll shell along the entire roll width and the quantity of suction air is also maintained at a desired, approximately constant value through the perforated sections (14) of the roll shell.

Suction roll with turbulence suppression element

A method in a drying group or groups provided with a single-wire draw in a multi-cylinder dryer of a paper machine in the draw of a web. The multi-cylinder dryer comprises drying cylinders heated by means of steam or equivalent, with the web being pressed by a drying wire against the cylinder faces of these drying cylinders. The multi-cylinder dryer has leading or lower cylinders on which the web runs outside the drying wire which is, for example, a felt. The leading cylinders or rolls are provided with holes passing through a mantle of the leading cylinders or rolls, these holes being fitted to open into an inner space of negative pressure within the leading cylinder or roll and to open, at an opposite end, into grooves provided on a mantle face of the rolls. The negative pressure inside the roll is arranged to be transmitted to the grooves provided on the outer face of the roll mantle, so that an adhesion force is applied to the web through the grooves. In the method, a negative pressure is applied to the entire inside mantle face of the roll, and free flow of air is permitted through the holes from an area above the cylinder and into the interior space within the cylinder. The present invention further concerns a device for use in the single-wire draw of the multi-cylinder dryer of the paper machine, and also to a paper-machine cylinder itself.

A multi-cylinder dryer for a paper machine having several drying groups situated one after the other, in which drying cylinders are situated one above the other in stacks, preferably in vertical stacks. In subsequent groups, a web is passed from one drying cylinder onto a next drying cylinder by way of a single-wire draw, so that the drying cylinders in the single-wire draw groups are situated outside the loops of their respective drying a wires. The web is passed as a supported draw from one single-wire group to a subsequent single-wire group by using at least two transfer-suction rolls. A first one of the transfer-suction rolls is situated inside a loop of a drying wire of the preceding single-wire draw group. The second or final transfer-suction roll is situated proximate to the first suction roll and inside a loop of a drying wire of the latter or subsequent single-wire draw group, proximate to a first drying cylinder in this subsequent group. Transfer of the web from one wire group to the next wire group takes place with support by a drying wire substantially all the time. At that location, the web is subjected to a difference in pressure that maintains the web in contact with a drying wire, generally a negative pressure being effective from the drying-wire side.

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Jyvaskyla, Finland

Heikki Ilvespaa