DuoDry CC, a new drying concept from Voith, is for the first time successfully in operation. The DuoDry CC is delivered and installed in the Narew PM 5 at Stora Enso in Ostroleka, Poland. The concept impresses with its reduced curl formation caused by the drying process and lowers energy demand by increased runability of the paper machine.
CC stands for curl control and designates the latest technology for reducing curl in single-tier dryer sections, which have become especially popular on the market since the speeds of paper machines have increased. The advantage of single-tier design when compared to the two-tiered design is that the machine achieves improved runability. However, a disadvantage of the conventional single-tier design is that the paper tends to curl due to the one-sided drying.
DuoDry CC solves this problem with a smart concept that is as effective as it is simple – a vertically inverted single-tier dryer group that serves as the last group. Normally the paper web is sprayed with water on one side to fight curl. The web is dried again afterward through additional energy input. With DuoDry CC, by contrast, the thermal energy already required for drying the paper web is utilized by being fed into the inverted dryer group from the other side. Thus no additional energy is required for reducing curl. Use of this technology reduces the operating costs of the paper machine. The components used, such as web stabilizers and dryer cylinders, are products that have long been proven, which ensures the reliability of the system in operation.
Janne Myllykangas, PM area manager at Stora Enso, confirmed after the project was finalized: “The collaboration with Voith was very good. The trust formed during the negotiations has been confirmed in the execution. The decision in favor of the DuoDry CC drying system has also proved to be the right one. We are very satisfied with the performance of DuoDry CC in operation.”
The Narew PM 5 from Voith is equipped with a SpeedSizer and produces 455,000 metric tons of testliner and corrugating medium per year on a wire width of 8,600 mm.
