Bringing headboxes up to their potential, Solutions!, Online Exclusives, March 2005, Vol. 88(3)
Many Valmet and Beloit single layer headboxes around the world are operating without any vanes installed. The reasons can be various. Some were supplied with flexible sheets, which have been removed by the mill; others never had any vanes installed from the beginning, due to old design standards.
In many of these headboxes the flow is not as stable as it potentially could be. A typical sign of this can be formation defects such as lower weight areas "moving" uncontrolled over the paper width.
Early on, both Beloit and Valmet (today both part of Metso Paper) realized the need for flow stabilizing elements in the headboxes. Beloit added the flexible Lexan sheets and Metso Paper developed the Turbo vane for its SymFloTis headbox. The result was remarkable, and now flow stabilizing members (with various names such as sheets, vanes, or wings) now are a typical part of new headboxes. Still, the improvement potential for existing, older headboxes is not quite realized by all their owners.
Concept III formation without sheets 
Concept III formation with sheets |
The SCA Ortmann difference
This is however not the case for SCA Hygiene Products’ Ortmann mill, Pernitz, Austria, where recently a set of carbon fiber sheets, the DuraSheets, were installed into the mill’s PM4, Europe’s widest tissue machine. DuraSheets are known for their durability and excellent performance.
Mr. Berger, Production Manager, PM4 comments, "installation of the Metso DuraSheets was very easy. It took only a few minutes. Because of the now stable micro turbulence in the nozzle area, a significantly improved formation, in MD and CD direction, has been achieved. The running time efficiency of the paper machine is still on a high level."
As for the HTB classic Valmet Headbox, several upgrades with installation of Turbo-vanes have been successfully executed both in Europe and in North America through the years. In all cases, mills have seen clear improvements. The latest one was supplied to SCA Kostheim, PM 4 and installed in November, 2004. Martin Klenk, the Kostheim mill’s production manager, confirms that the formation quality has improved.
The DuraSheet needs no special design change to the headbox. If the headbox was designed to accept sheets, DuraSheets can be built to fit and will slide into the existing slots without any problems. The HTB headbox needs an adapter piece built into it; however, this operation is still quite easy and fast. Formation improvement is immediate. Metso has more than 40 years experience with headbox vanes.
For further information please contact:
Bringing headboxes up to their potential, Solutions!, Online Exclusives, March 2005, Vol. 88(3)
