Valmet Corporation

Valmet Paper Machinery Inc.

Seppo Rantanen

Raimo Virta

Vesa Vuorinen

Pekka Eskelinen

A method for causing adherence of a web to a drying wire so as to prevent the effects of centrifugal forces and of other air-flow phenomena, which effects attempt to separate the web from the drying wire in dryer groups having a single-wire draw and arranged in a multi-cylinder dryer of a paper machine. The dryer groups include heated drying cylinders, a drying wire for pressing the web against outer cylinder faces of the drying cylinders, and guide cylinders or rolls on which the web runs on the outside face of the drying wire. The guide cylinders have perforations which pass through the cylinder mantle and open into an inside space in the interior of the guide cylinders which is subjected to a vacuum. The vacuum in the guide cylinders is transferred to the outside face through the perforations. The guide cylinders have shafts on which the guide cylinders are mounted revolving. The vacuum level in the guide cylinders is regulated by means of the air quantity in compliance with the threading/running stage and/or running speed and/or with any other process or running parameter of the dryer section of the paper machine so that the effect of the vacuum is sufficient to keep the web in reliable contact with the drying wire.

Method and arrangement in a multi-cylinder dryer of a paper machine

The present invention concerns a device for generating negative pressure inside a cylindrical roll mantle of a revolving roll. The roll has a roll mantle provided with through-holes, grooves or equivalent apertures and confining a suction chamber in the interior thereof, in which a negative pressure can be generated by suctioning air out of the suction chamber. A suction flow directed towards the suction chamber thereby prevails in the holes, grooves or equivalent apertures of the roll mantle. At least one rotor blower or equivalent is attached to the roll to revolve along with the roll, with an intake side of the rotor being connected to the suction chamber of the roll. The movement of rotation of the roll thereby produces rotary movement of the rotor or equivalent, which in turn generates negative pressure in the suction chamber. Thus, in the arrangement in accordance with the present invention, external equipment of negative pressure or a separate piping system is not needed.

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Merimasku, Finland

Seppo Rantanen