Patent ID: 6128833
Filing Date: 2000-10-10
Classification: D21F

Abstract:
In a dryer section of one of a paper and board machine comprising a plurality of drying groups through which a web is passed, said plurality of drying groups including at least one single wire draw drying group, said at least one single wire draw drying group including suction cylinders, heated drying cylinders, a drying wire on which the web is carried and guide means for guiding said drying wire while the web is carried thereon between said suction cylinders and said drying cylinders, the drying wire being guided from one of said suction cylinders to one of said drying cylinders, from said one of said drying cylinders to another one of said suction cylinders and from said another suction cylinder to another one of said drying cylinders and such that the web is interposed between a face of each of said drying cylinders and said drying wire while running over said drying cylinder and said drying wire is interposed between the web and said suction cylinders while running over said suction cylinders, the improvement comprising:impingement units each arranged in opposed relationship to a respective one of said drying cylinders and including means for directing a heated medium through said drying wire at the web to produce a two-sided drying effect about said respective drying cylinder to prevent the curling of the web,said drying wire having an air permeability value higher than 1500 m.sup.3 /m.sup.2 /hour;said respective drying cylinder being one of said drying cylinders in said at least one single wire draw drying group which enables said impingement unit arranged in opposed relationship thereto to effect an increase in the drying capacity of said at least one single wire draw drying group.