Valmet Corporation

Valmet Paper Machinery Inc.

Metso Paper Inc.

Antti Kuhasalo

Heikki Ilvespaa

Juha Kaihovirta

Reima Kerttula

Allan Liedes

Seppo Elijoki

Antti I Ilmarinen

Pertti Heikkila

Jouko Yli-Kauppila

Mikko Karvinen

Hans Sundqvist

Matti Korpela

Pekka Taskinen

Dick Parker

Henrik Petterson

Jorma Laapotti

Kari Juppi

Antti Komulainen

Juha Lipponen

Harri Happonen

Olavi Viitanen

Vaino Sailas

Pasi Ahonen

Matti Kurki

Martti Salminen

Ilkka Jokioinen

Juha Ojanen

Kristian Hamstrom

Va/ Ino/ Sailas

J&auml;rkko Nurmi

Iikka Jokioinen

An apparatus for a dryer section of a paper or board machine has a drying group (R) and an impingement drying unit () which is placed above and/or below a row (DSR) of drying cylinders (). A drying fabric () supported paper or board web () is conducted past the impingement drying unit () having at least one impingement surface (IP, IP) the side profile of which is straight, changeably curved in its radius of curvature, in the shape of a broken line or a selectable combination of these, and that the impingement surface or a tangent line to the impingement surface or a line passing via the beginning and the end of the impingement surface or an extension of the line forms on the impingement side an angle with a horizontal plane parallel to the machine level, which angle is &#x2266;120&#xb0;, advantageously 120&#xb0;&#x2013;60&#xb0;, most advantageously about 90&#xb0;.

Impingement drying unit and a dryer section

A method and apparatus effect drying of a paper web using a plurality of heated drying cylinders and at least one air impingement module having a hood. The paper web is brought into operative contact with the heated drying cylinders, and at least one of the final moisture content, quality, and cross-direction profile of the paper web is regulated. The regulation is effected by adjusting the efficiency of air impingement drying of the paper web, by adjusting at least one of the blowing velocity of the medium (typically air) blown against the paper web, the humidity of the blowing medium, and the distance of the hood of the impingement module from the paper web. At least one of the final moisture content of the paper web and its quality may also be regulated by adjusting the steam pressure of one or more drying cylinder groups. Typically the final moisture content of the web is measured after the last drying cylinder group and the efficiency of air impingement drying is regulated on the basis of that measurement.

Method and apparatus for drying a paper web

A method and arrangement for drying a paper to be surface-treated, in particular fine paper, in an after-dryer in a paper machine. The paper web is first dried in a forward dryer section of the paper machine by one or more groups with single-wire draw that are open downward on support of a drying wire, the paper web is then finished in a finishing section, e.g., surface-sized or coated, and thereafter, the paper web is dried by an upwardly open inverted group with single-wire draw. In the inverted group with single-wire draw, the tendency of curling formed in the paper web in the forward dryer section can be substantially eliminated and/or compensated for. In the alternative, to eliminate or compensate for the tendency of curling formed in the paper web in the forward dryer section, hot moist air may be fed into certain locations into connection with the dryer groups in an after-dryer in order to restrain the evaporation, or hot dry air may be fed in order to promote the evaporation from the side of the web that is desirable in view of the control of curling.

After-dryer in a paper machine

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 dryer section of a paper machine including groups with single-wire draw that include a drying wire guided in a loop and reversing cylinders arranged in the drying-wire loop. Contact drying cylinders are arranged in gaps between the reversing cylinder and the drying wire is guided to press a web against heated faces of the contact drying cylinders. In addition to normal, small-diameter contact drying cylinders, one or more large-diameter contact drying cylinders (the diameter being greater than about 2200 mm and usually in a range from 2200 mm to 3600 mm), is/are used in one or more single-wire draw groups. An impingement-drying/ventilation hood is arranged above the large-diameter contact drying cylinders and extends on a large sector above the contact drying cylinder and above the drying wire and the web running over the cylinder. An impingement-drying/ventilation effect is applied to the drying wire through the impingement-drying/ventilation hoods on the large sector. By means of the effect, a moist boundary layer in contact with the drying wire is disintegrated and drying is promoted from a side of a face of the web opposite to the web face that is placed against the contact drying cylinders.

Dryer section in a paper machine in which impingement and/or ventilation

A dryer section of a paper machine which is provided with at least one intermediate calendering nip and includes several successively arranged wire groups. The dryer section primarily or exclusively has groups with single-wire draw in which heated drying cylinders are arranged in an upper row and reversing suction cylinders or reversing suction rolls are arranged in a lower row below the upper row. The groups with single-wire draw also have a drying wire which runs along a meandering path over the drying cylinders and reversing suction cylinders or rolls so that the reversing suction cylinders remain inside the loop of the drying wire. A calender roll is arranged in opposed relationship to a drying cylinder in one or more of the single-wire draw groups in a sector which the first face of the web is exposed to thereby define a calendering nip therewith.

Dryer sections with intermediate calendering in a paper machine

A dryer section of a paper machine which is provided with at least one intermediate calendering nip and includes several successively arranged wire groups. The dryer section primarily or exclusively has groups with single-wire draw in which heated drying cylinders are arranged in an upper row and reversing suction cylinders or reversing suction rolls are arranged in a lower row below the upper row. The groups with single-wire draw also have a drying wire which runs along a meandering path over the drying cylinders and reversing suction cylinders or rolls so that the reversing suction cylinders remain inside the loop of the drying wire. Two calender rolls are arranged to form the calendering nip through which a paper web to be dried is passed, and thus calendered inside the dryer section, immediately preceding or following or within one or more of the dryer groups of the dryer section.

A dryer section of a paper machine which is provided with at least one intermediate calendering nip and includes several successively arranged wire groups. The dryer section primarily or exclusively has groups with single-wire draw in which heated drying cylinders are arranged in an upper row and reversing suction cylinders or reversing suction rolls are arranged in a lower row below the upper row. The groups with single-wire draw also have a drying wire which runs along a meandering path over the drying cylinders and reversing suction cylinders or rolls so that the reversing suction cylinders remain inside the loop of the drying wire. In one representative embodiment, at a drying cylinder situated inside the group with single-wire draw or in connection with the last drying cylinder in the group, a free space is arranged in which a calender roll is arranged to form the calendering nip together with the drying cylinder in the group with single-wire draw through which a paper web to be dried is passed and, thus, calendered inside the dryer section.

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 group with single-wire draw in a dryer section of a paper machine having heated smooth-faced drying cylinders against whose smooth face a paper web to be dried is brought into direct contact, and reversing cylinders. The group with single-wire draw also includes a drying wire which is guided in a loop by guide rolls as well as by the drying cylinders and reversing cylinders so that the drying cylinders are placed outside the wire loop and the reversing cylinders are situated in gaps between the drying cylinders inside the loop of the drying wire. In the group with single-wire draw, the drying cylinders include large cylinders and small cylinders, the diameter of the large cylinders is substantially larger than the diameter of the small cylinders. The small cylinders are placed in gaps between the large cylinders so that their centers of rotation are on a level substantially different than the level of the centers of rotation of the large cylinders. The reversing cylinders are arranged on the runs of the drying wire and the web from a large cylinder to a small cylinder and from a small cylinder to a large cylinder, the centers of the reversing cylinders being placed on a level substantially different than the corresponding levels of the large cylinders and the small cylinders.

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Jyvaskyla, Finland

Antti Kuhasalo