New Suction Press Roll Improves Dryness, Runnability on Norske Skog Bruck PM 4

Norske Skog, Norway, after installing a Voith (Germany) EvoFlow P suction press roll on PM 4 at its Bruck mill in Styria, Austria, reports that it has been able to increase dryness by 0.5%. Additionally, web draw after the third press as well as startup behavior of the felts were considerably enhanced and overall runnability has improved significantly. The Bruck mill, which Norske Skog acquired in January 1996, produces both lightweight coated (LWC) papers and newsprint.

The project began after Norse Skog Bruck commissioned Voith to examine whether dryness could be increased on its PM 4 by at least 0.5% after the fourth press. A stock analysis performed by Voith revealed that this could be achieved by increasing the line load in the first and second press. Since specifications of the existing suction press roll did not meet new requirements resulting from the increased line load, Norske Skog Bruck ordered the installation of a new EvoFlow P suction press roll with a SolarFlow high-capacity roll cover from Voith. This polyurethane roll cover features a modified groove dimension, helping to increase drainage significantly.

The new roll dimensions were designed for a nip load of 120 kN/m. The existing bearing housings were re-used. In addition, a mechanical deckle adjusting unit was installed in the low-vacuum zone.

PM 4 produces 275,000 metric tpy of LWC paper in a basis weight range of 34 to 54 gsm, with an operating speed of 1,400 m/min.

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