Wash press upgrade boosts productivity and extends the lifecycle of the fiberline at Sappi’s Gratkorn mill
The long-term relationship between Sappi’s Gratkorn mill and Valmet drives continuous development. Most recently, Valmet supported the mill with two upgrades on its TRP wash press, resulting in improved reliability and increased productivity. In addition, a Roll Agreement secures the availability of skilled resources, enabling lifecycle support and cost predictability.
With over 400 years of paper production experience, Sappi’s Gratkorn Mill in Austria is designed to produce superior-quality paper using the latest technology. The mill has an annual capacity of 990,000 tons of triple-coated fine paper on two paper machines and 250,000 tons of totally-chlorine-free chemical pulp.
The partnership between Gratkorn mill and Valmet goes back many years, always focusing on optimizing the mill’s processes and extending the lifecycle of the equipment. Over time, Valmet has delivered several extensive rebuilds on the mill’s fiberline and two paper production lines. To further improve the performance of their fiberline, Gratkorn recently invested in Valmet ProNip and Valmet Inlet ProFlow solutions.
“The main target of the upgrade was to eliminate plugging challenges we had with the wash press. Valmet, as the original equipment manufacturer, was a natural choice to deliver the upgrade,” says Stefan Hansen, Project Manager, Sappi Gratkorn.
Result: higher inlet consistency and improved washing efficiency
Valmet’s delivery included two tailored solutions designed to improve washing efficiency. Valmet ProNip is a mechanical upgrade that allows the roll nip to be adjusted during operation, ensuring stable outlet consistency. Valmet Inlet ProFlow includes a new inlet box and rotor, increasing reliability by minimizing plugging risk at inlet. Both solutions are easy to install, and their payback time is around 18 months.
The delivery and installation were executed within the agreed timeframe, and the system is now fully operational.
“We had some challenges with optimization, but once the equipment was up and running, the results have been satisfying. There is significantly less cleaning, leading to more reliable and increased production,” Hansen says.
Comparing production data before and after the upgrade shows that consistency increased by two percentage points, and the dilution factor increased to the optimal range (3,0-3,4l/kg), resulting in higher inlet consistency and improved washing efficiency. Chemical Oxygen Demand (COD) decreased by 19%. The press nip has been successfully reduced from an initial 16 mm to approximately 12,4 mm.
In the event of failure under full load, the press can be started without issues such as blockages. It is extremely rare that the VAT requires cleaning. The start-up behavior is excellent, and there are minimal torque fluctuations during operation. Overall, the upgrade improved the washing efficiency and productivity of our fiberline,”
Roll agreement secures performance throughout the equipment lifecycle
In addition to project-based improvements, Sappi Gratkorn know-how on a continuous basis. Next, Valmet is to recondition one of the mill’s Twin Roll Press rolls.
Additionally, with an on-going roll agreement, the mill has easy access to Valmet’s services, supporting the mill’s performance at all stages during the equipment lifecycle.
“The roll agreement secures the availability of various resources with a predictable throughput time. It helps us plan our maintenance costs in advance. We’ve been very satisfied with the professionalism of Valmet’s experts and the work conducted under the roll agreement,” says Markus Reinbacher, Maintenance Manager, Sappi Gratkorn.
Looking ahead, Sappi Gratkorn is eager to learn about new technologies and opportunities to further optimize its processes – and Valmet is always ready to support.
Author: Marianne Valta
