Transferring St. Mary's GW System to Meet the Challenges of Producing High Quality Printing Papers in New Millenium, 1999 Pulping Conference Proceedings

Lassi Halonen

Ahlstrom Machinery

Gunnar Kristiansen

St. Marys Paper Ltd.

St Marys Paper has done a major GW system rebuild. The screen room was updated from centrifugal screening technology to 0.12 mm (0.05”) slotted screening. The shive count after the screen room was reduced by 85% compared to their old system. The GW freeness was reduced as well. The centrifugal cleaners after the screen room were removed and replaced with a small cleaner system handling only about 10% of the flow. This resulted in major energy savings. The reject refining system was expanded to handle more rejects and refine more shives to usable fibers. A post refining system was installed to further reduce the shive count and freeness. Understanding of the whole GW system was increased significantly with the installation of an automated pulp quality analyzer. The analyzer has allowed for optimization of the system for better quality and lower production cost.

The rebuilt system has significantly improved the paper quality and decreased the production cost. The major quality items improved were pressroom breaks, smoothness and printability. The major production cost savings are coming from fewer papermachine breaks, energy cost and less kraft usage.