Oy Tampella Ab

Metso Paper Inc.

Valmet Corporation

Veli-Matti Rajala

Jouko Hautala

Petri Nyberg

Sakari Soini

Kati Lindroos

Juhani Ahonen

Ismo Hourula

Jukka Heimonen

Elina Pohjala

Jussi Ahola

Pentti Saarenrinne

A screen and a method for screening pulp. The screen comprises a body, a screen cylinder arranged inside the body for screening the pulp, and an accept chamber and an accept aggregate connected with it for removing the accepted pulp fraction from the screen. The accept chamber is arranged between the screening surface of the screen cylinder and the screen body and it is arranged to expand in the radial direction of the screen cylinder outwards from the screen cylinder continuously in the longitudinal direction of the screen cylinder towards the line which is parallel to the radius of the screen cylinder and corresponds to the cross-section of the body and on which the accept aggregate is arranged.

Screen and method for screening pulp

The invention relates to a method of mixing pulp components in the manufacture of paper, in which method the pulp components to be mixed are led to a mixing point along tubes arranged inside each other. The pulp component flows are mixed by generating turbulence in them by means of the end of an inner tube, the cross-section of which end is wave-like. This turbulence is guided and its effect is intensified by means of form parts in connection with the mixing point, which form parts are arranged on the inner surface of the outer tube. Further, the invention relates to an arrangement implementing the mixing of pulp components in accordance with the method.

Method and arrangement for mixing pulp components in the manufacture of paper

An apparatus for cleaning a fiber mass suspension, the apparatus comprising a receptacle and an inlet channel and an outlet channel for feeding the suspension into and for discharging it from the receptacle. In addition, the apparatus comprises air feed means for feeding air into the lower portion of the receptacle. The apparatus comprises at least one partition wall dividing the receptacle into spaces in such a way that the suspension may flow between the spaces at the lower portion and the upper portion of the partition wall, respectively. The air feeding means are positioned to feed air into one aeration space, whereby the air separates impurities from the suspension and makes the suspension flow on different sides of the partition wall upwards and downwards, respectively, so that a spiral flow is created around the partition wall from the inlet channel into the outlet channel.

Apparatus for cleaning a suspension, preferably a fiber mass suspension

The invention relates to a method for controlling pressurized screening devices in which fiber pulp is fed to the pressurized screening device and is divided into the accepted portion of the fiber pulp passing through perforations of a cylindrical screenplate and the rejected portion which is removed from the screenplate, the perforated screenplate being treated by a device movable relative thereto and rotatable around the center axis of the screenplate, the fiber pulp being fed parallel with the center axis of the screenplate to baffle blade assembly comprising at least two baffle blades and also being rotatable around the center axis, wherein the speed of rotation of the baffle blade assembly and/or the radial dimension of the baffle blades are adjustable to control the screening. The invention additionally relates to pressurized screening devices for implementing the method.

Method for controlling pressurized screening devices and pressurized

The invention relates to a method and a screening apparatus (1) for screening pulp. In the method, the maximum length of fibres and shives flowing through holes (4a) in a screen drum (4) is adjusted by moving blades (8) with a sharp front edge close to the surface of the screen drum (4) in such a manner that the sharp edge (8a) of the front face moving closest to the drum surface strikes shives or long fibers passing through the hole (4a) and pulls them back. The rate of travel of the blades (8) is so adjusted that the pulp flows in the hole (4a) only over a distance corresponding to the predetermined fiber length during the interval between the front edge of two successive blades (8). The screening apparatus (1) comprises blades (8) moving in parallel with the surface of the screen drum (4). The front edge of the blades defines in cross-section a sharp angle, the point of the angle defined by the front edge moving closest to the surface of the screen drum (4).

Method of screening pulp and a screening apparatus

The invention relates to a device for screening pulp, comprising a screen drum (2) provided with holes for the passage of an accepted pulp fraction therethrough; and a blade (10) for a screening device. The device comprises straight blades (10) wiping the surface of the screen drum (2) and extending in parallel with the axis of the screen drum (2). Reject which does not pass through the screen drum (2) is removed through a reject discharge opening (5) at the other end of the screen drum. For transferring the reject from the surface of the screen drum (2) to the reject discharge end, the surface of the blades (10) is on the screen drum side provided with grooves (11) so inclined that the front end of the groove (11) is closer to the pulp input than the rearmost end of the same groove (11). Thereby each groove (11) in the blades (10) causes the reject to be transferred towards the reject discharge opening (5).

Growing community of inventors

Tampere, Finland

Veli-Matti Rajala