Valmet Corporation

Valmet Paper Machinery Inc.

Lauri Verkasalo

Ari Linsuri

Erkki Partanen

Michael H Odell

Jyrki Jaakkola

Jouko Hautala

Antti Poikolainen

Heikki Ilvespaa

Antti Suonper&auml;

Mauri Koivuranta

Timo Pekkarinen

Mari Silanter&auml;

Juha Kinnunen

Pasi Turpeinen

Heikki Ilvesp Aa

A process arrangement for the short circulation in a paper or board machine including stock chests for component stocks, metering pumps for component stocks, cleaning devices, pumps, a headbox and a wire section as well as a system of pipes connecting these elements, together with regulation devices. After the metering pumps, the component stock flows are passed into a closed mixing volume in which the component stocks are mixed and diluted with a first dilution water flow. From this closed mixing volume, the stock is passed in a closed space by a first feed pump of the main line of the process through a screen and a centrifugal cleaner to the suction side of a second feed pump of the main line, where a second dilution water flow is passed to the stock. The second feed pump feeds the stock through a machine screen to the inlet header in the headbox.

Process arrangement for the short circulation in a paper or board machine

A roll and blade gap former for a paper machine having first and second wires guided in a respective loop and defining a twin-wire forming zone, a forming gap in which the first and second wires converge before the twin-wire zone, a headbox including a slice channel having a slice opening through which a stock suspension jet is fed into the forming gap to form a web between the wires, and drainage and forming elements arranged in the twin-wire zone for removing water from the web. To provide an improvement in the control of the Z-direction properties of the web, the former includes turbulence generating vanes arranged in the slice channel in the headbox to cause turbulence in the stock suspension jet upon its discharge from the slice opening into the forming gap and a first forming roll arranged in the twin-wire zone and which constitutes the first drainage and forming elements in the twin-wire zone after the forming gap. A run of the twin-wire zone after the forming gap is curved over a wrap angle sector of the first forming roll which is less than about 25.degree.. The forming and draining elements produce a pulsating pressure effect on the web after the curved run of the twin-wire zone over the wrap angle sector of the first forming roll. A method for controlling the anisotropy of web formed in a roll and blade former is also described.

Controlling web anistropy in a roll and blade twin-wire gap former

A twin-wire gap former in a paper machine in which an outer wire and an inner wire are guided by guide rolls and by web forming members. The wires form a twin-wire zone which starts from a forming gap into which a slice part of a headbox feeds a stock suspension jet. The forming gap is followed by a curved portion of the twin-wire zone which is guided by a first forming roll placed inside the loop of one of the wires. The forming-gap arrangement includes two opposite tip plates which define a slice channel between them. The lip plates extend deep into the forming gap so that the free ends of the lip plates are placed in direct vicinity of the forming wires or in contact with the wires. On the curve sector of the twin-wire zone, which starts after the forming gap and which is guided by the first forming roll, inside the loop of one of the wires, a water drainage box is provided, at which box the edges of the sides that are placed against the inner face to the wire are substantially sealed. The water drainage box is connected to devices which regulate the pressure/pressures in the space or spaces placed in the interior of the box and are filled with water. Then, the drainage of water is controlled both in the forming gap and on the curve sector following after the forming gap.

Twin-wire gap former in a paper machine

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

A method, device, and arrangement in a paper machine for regulating the control of the transverse profile or profiles of properties of a paper web produced therein. Water is removed from the paper web under compression between two forming wires by making use of dewatering and/or forming ribs. The deflection of the dewatering and/or forming ribs in the transverse direction of the web is regulated thereby affecting the retention profile of the paper web in the cross direction. By regulating the deflection of the dewatering and/or forming ribs, the transverse fiber-orientation profile and/or the filler profile of the paper web is influenced through the control of the transverse retention profile of the web.

Method, device and arrangement for regulating the control of a

A twin-wire web former in a paper machine includes a covering wire and a carrying wire defining a forming zone, at the beginning of which zone there is a forming gap into which the discharge opening of a headbox feeds a pulp suspension jet. A first forming roll is located on the twin-wire zone, in the area of the forming gap, on which the twin-wire zone is curved within a certain sector, followed by a dewatering unit(s), which is in turn followed by a second forming roll(s) in the twin-wire zone. Thereafter, the web is detached from the covering wire and passed on the carrying wire to a pick-up point. Between the first forming roll and the second forming roll(s), a dewatering unit(s) is provided which comprises a press-support unit which guides the wire that enters into contact with the unit as a straight run. The dewatering unit(s) also includes a dewatering equipment facing the press-support unit and provided with suction and foil equipment for removing a substantial amount of water out of the web. The magnitude of the twin-wire turning sector placed in connection with the first forming roll is within the range of from about 35.degree. to about 120.degree..

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Jyvaskyla, Finland

Lauri Verkasalo