The success story of Valmet Hirun Web Stabilizer P continues
May 12, 2017
Improved sheet runnability and paper quality at Holmen Paper Braviken Mill.
Paper machine PM 53 at Holmen Paper’s Braviken mill produces grades ranging from newsprint to sophisticated SC papers. The single-tier dryer section of PM 53 includes eight drying groups, all originally equipped with vacuum stabilizers. In a rebuild last fall, two old stabilizers were replaced with new Valmet Hirun Web Stabilizer P's* in the first and second drying groups. While introducing new Hirun technology, the existing vacuum rolls and suction air system were utilized.
Proven improvement in sheet stability from day one
The rebuilt hirun web stabilizer P system was successfully started up in September 2016, and its performance has met all the requirements for a stable sheet run and lower draw. The rebuild enabled a decrease in the press-to-dryer draw of at least 8%, which in turn lead to a 4.4% increase in stretch at break and a boost in tensile strength of 4.7%.
Superintendent Fredrik Rothman is pleased with the results: “This was an interesting rebuild with new technology, resulting in proven enhancements in sheet stability from day one! The long-term results with reduced draw and higher tensile strength have definitely exceeded our expectations.”
The hirun web stabilizer P is an application for perforated roll concepts with proven Hirun technology. The main benefit of this technology is its high vacuum level, which gives excellent sheet runnability and enables draw reduction.
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Braviken PM 53 was commissioned in 1996, and until 2015, it produced newsprint and uncoated magazine paper. After an upgrade in 2015, PM 53 now produces paper in a basis weight range of 34–50 g/m2,with grades ranging from newsprint to sophisticated SC papers, including the recently developed Holmen UNIQ SC paper. PM 53 has a wire width of 9.65 m, a designed speed of 1,700 m/min, and an annual production capacity of 310,000 tonnes. |
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Holmen Paper is a specialty paper producer that uses the properties of virgin fiber to provide cost-effective alternatives to traditional paper choices. At its Braviken mill in Sweden, Holmen Paper operates two paper machines – PM 52 and PM 53 – producing magazine, book and SC paper, as well as newsprint. The mill’s own TMP lines produce the pulp needed for production. |
*earlier known as HiRun P