Valmet Paper Machinery Inc.

Valmet Corporation

Valmet Oy

Mikko Karvinen

Jorma Laapotti

Juhani Pajula

Reima Kerttula

Pekka Taskinen

Antti I Ilmarinen

Antti Kuhasalo

Heikki Ilvespaa

Pertti Heikkila

Jouko Yli-Kauppila

Juha Kivimaa

Matti Korpela

Dick Parker

Henrik Petterson

Vaino Sailas

Martti Hirsimaki

Ilkka Jokioinen

Va/ Ino/ Sailas

Iikka Jokioinen

Martti Hipsimaki

Jorma Lapotti

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 closed press section in a paper machine including a compact combination of press rolls, some of which define press nips with each other between which the web has a closed draw supported by the face of a fabric. The press section has a center roll in connection with which at least one press nip is formed. A closed loop of a transfer band is passed around the center roll. The web is transferred on an outer face of the transfer band after the last press nip in the compact combination of rolls as a closed and constantly supported draw onto a drying wire in a drying section following after the press section. The transfer band loop is preferably made of a fabric that substantially does not receive water and does not rewet the web. The web-adhesion properties of the outer face of the transfer band are chosen so that, after the last nip, the web follows the transfer band, and so that the web can be transferred as a fully closed draw onto the drying wire. In connection with the loop of the transfer band, means for conditioning/cleaning the band and/or safety devices are provided, by whose means an adequate operation of the transfer band is maintained.

Compact press section in a paper machine

Method and device in the manufacture of paper or board for dewatering of a paper web that is being manufactured. The paper web is transferred from a forming wire onto a wire in the drying section while constantly on support of a fabric that receives water, a transfer fabric, or of any other, corresponding transfer surface as a closed draw, at a particularly high speed, which is higher than about 25-30 m/s. Dewatering of the paper web is carried out by means of at least two subsequent press nips, of which nips at least one press nip is a so-called extended-nip zone, whose length in a machine direction is larger than about 100 mm. The extended-nip zone is formed in connection with a mobile flexible press-band loop. The distribution of the compression pressure employed within said extended-nip press zone is regulated and/or selected both in the transverse direction of the web and in the machine direction so as to set or to control the different profiles of properties of the web.

Device for dewatering of a paper web including prepressing with extended

The invention relates to a closed press section in a paper machine and comprises a compact combination of press rolls. Several of the rolls define press nips with each other, between which nips the web has a closed draw supported by the face of a fabric. The press section has a center roll in connection with which a press nip or press nips are provided. A closed loop of a transfer band is passed around the center roll. The web is transferred on an outer face of the transfer band after the last press nip in the compact combination of rolls as a closed and constantly supported draw onto a drying wire in a drying section following after the press section. The transfer band loop is made of a transfer band fabric that substantially does not receive water and does not rewet the web. The web-adhesion properties of the outer face of the transfer band fabric are chosen so that, after the last nip, the web follows the transfer band fabric, and so that the web can be transferred as a fully closed draw onto the drying wire. In connection with the loop of the transfer band fabric, means for conditioning of the band and/or safety devices are provided, by whose means an adequate operation of the transfer band fabric is maintained.

Compact press section with closed draw of the web in a paper machine

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

Method for dewatering of a paper web by pressing using an extended nip

Closed press section in a paper machine, comprising a compact combination of press rolls. Certain of rolls define press nips with each other, between which nips the web has a closed draw supported by the face of a fabric. The press section has a center roll in connection with which a press nip or press nips are provided. A closed loop of a transfer band is passed around the center roll. The web is transferred on an outer face of the transfer band after the last press nip in the compact combination of rolls as a closed and constantly supported draw onto a drying wire in a drying section following after the press section. The transfer band loop is made of a transfer band fabric that substantially does not receive water and does not rewet the web. The web-adhesion properties of the outer face of the transfer band fabric are chosen so that, after the last nip, the web follows the transfer band fabric, and so that the web can be transferred as a fully closed draw onto the drying wire. In connection with the loop of the transfer band fabric, means for conditioning of the band and/or safety devices are provided, by whose means an adequate operation of the transfer band fabric is maintained.

A press section of a paper machine includes, in the direction of web run, at least three successive, separate press nips for dewatering a web, the web passing between the nips in a closed draw. The web is dewatered in the first nip through both of its faces. The press section includes at least one upper fabric and lower fabrics, the first fabrics in the direction of web run being water-receiving fabrics arranged such that one of the first fabrics acts as a press fabric in the first nip while the other of the first fabrics acts as a press fabric both in the first as well as in the second nip. Of the second fabrics in the direction of web run, the upper fabric is a water-receiving press fabric while the second lower fabric is a substantially non-water receiving transfer fabric or belt on which the web is transferred from the third press nip to the following drying section as a closed draw. The third separate press nip comprises an extended-nip press, the length of the nip zone thereof being substantially larger than the lengths of the zones of the preceding roll nips. The web runs through the nip zone of the extended-nip press supported on its bottom side by the substantially non-water receiving transfer fabric, the upper water-receiving fabric being pressed against the other side of the web.

Press section with separate press nips in a paper machine

A press section of a paper machine comprises, in the direction of web run, at least three separate press nips for removing water from a web, the web passing between two fabrics in each of the three nips. Dewatering of the web takes place through both faces of the web at least in the first press nip which is formed between two open-faced press rolls. The second and third press nips are formed between an open-faced roll and one of an open-faced roll and a smooth-faced roll. According to the invention, the press section includes two upper fabrics and two lower fabrics, the first upper and lower fabrics in the direction of web run being water-receiving press fabrics, one of which constitutes a press fabric only in the first press nip, the other fabric constituting a press fabric both in the first and second press nips. One of the second upper and lower fabrics is a water-receiving press fabric, the other being a water-non-receiving transfer fabric adapted to receive minimal amounts of water, if any. The web is transferred on the transfer fabric after the third press nip as a closed draw into the drying section which follows the press section.

A dewatering press section for a paper or cardboard web includes a press roll having a wide pressing zone over which a belt is provided to run guided by guide rollers with the web being arranged to run in the pressing zone in compression between the press roll and the belt. At least one fabric runs in the pressing zone and acts on a respective face of the web. A pressure transmitting device has a surface which overlies the belt substantially in the pressing zone. According to the invention, ultrasonic field generators are provided in association with the pressure transmitting device surface for applying an ultrasonic field substantially in the pressing zone such that the friction between the surface of the pressure transmitting device and the belt is substantially reduced. The ultrasonic field generators can operate at a single frequency, at a plurality of discrete frequencies or may emit a continuous spectrum of frequencies and the intensity of the ultrasonic field is selected such that in addition to reducing the friction between the belt and the surface of the pressure transmitting device, the ultrasonic field will also substantially promote the removal of water from the web within the pressing zone as well as the transfer of water removed from the web into the press fabric or fabrics.

Paper machine press with a wide pressing zone

Growing community of inventors

Vihtavuori, Finland

Mikko Karvinen