New Hard Nip Sizing Technology started-up by Valmet at Propapier in Germany

 

Valmet(Finland)-delivered, a completely new type of a sizer, OptiSizer Hard, with related chemical systems were successfully started up at Propapier PM1 GmbH Burg mill in Germany a day ahead of schedule on April 19, 2018. The production line PM1 produces liner, fluting and kraft substitutes grades based on 100% waste paper. Thanks to a very good cooperation and a purposeful project work, all the produced containerboards have been saleable from the very start.

A prototype product and a very tight shut-down schedule is a challenging combination. Despite the initial setup, most of the targets were achieved right after the start-up. The web passed through the nip smoothly and runnability was excellent. The new technology shows already a great potential to achieve the goals regarding strength properties and steam consumption.

"I was quite amazed to see the fast start-up of our new sizer. Earlier, high web tension levels were causing quite a bit of challenges to runnability. It looks like this obstacle no longer exists. We have achieved the targeted quality specification and now we can focus on the further benefits we are aiming at e.g. steam savings, higher strength levels or starch savings," says Phillipos Vrizas, Technology Manager at Propapier.

"The very first closing of the nip rolls is a moment telling a lot about any new sizer - especially a prototype sizer. It looked perfect. I couldn't see any web tension induced wrinkling in the web. The schedule was very tight with only a 11-day shutdown time. The fact that we were able to squeeze it into a 10-day break was quite amazing and a proof of an excellent cooperation and preplanning," said Jani Hakola, Development Manager at Valmet's Board and Paper Mills Business Unit.

Valmet's delivery included a new sizer called OptiSizer Hard. Compared to conventional sizer, OptiSizer Hard has a pair of hard cover nip rolls. Starch is sprayed on the rolls which transfer the starch into the nip where it is further transferred into paper web.

Strength is among the most important benefits with OptiSizer Hard. Starch is dosed in the roll nip with higher nip pressure, which increases the density of fibers. This leads into better strength properties. To mention a few other benefits of OptiSizer Hard, the life cycle costs are lower due spray application and runnability is better due to better nip profile control.

The existing and outdated starch preparation system was replaced with Valmet's starch preparation system specially designed for OptiSizer Hard and its spray application method. The properties of produced starch have substantially lower range of variation, which helps to produce liner boards within the targeted quality specifications. The delivered supply system is fully automated and equipped with pressure screens.

To further improve the properties of liner and fluting grades Propapier is producing, a cooperation agreement of 20 weeks was made. The target of the agreement is to find the best practices with the new sizer e.g. by reducing energy consumption, and by further improving liner and fluting properties, such as the lighter basis weight of containerboards without compromising other important properties.