Patent ID: 6412192
Filing Date: 2002-07-02
Classification: D21F

Abstract:
A method for ventilating an offset pocket space located in a drying section of a papermaking machine, the offset pocket space being situated between three axially parallel drying cylinders over which consecutively runs a paper web, a first and a third of these cylinders being vertically spaced from a second of the cylinders, the paper web being pressed against the first and the third cylinder by a felt which further runs over a felt roll having a rotation axis parallel to that of the cylinders, the felt roll being disposed between the three cylinders in an offset position which is closer to the first cylinder than the third cylinder, the offset pocket space being delimited by a first cleft defined where the felt and the paper web separate, a first draw of the paper web from the first cleft to the second cylinder, a free portion of the second cylinder, a second draw of the paper web from the second cylinder to a second cleft defined where the felt and the paper web rejoin, and the felt between the first cleft and the second cleft, the method comprising the steps of:directing a first air stream from a first outlet into a third cleft defined where the felt and the felt roll join, the first air stream flowing through the felt and lifting the paper web away from the felt to reach the offset pocket space; directing a second air stream from a second outlet in close proximity of the felt, the second air stream being supplied at a location which is upstream the third cleft and in a direction which is substantially opposite the running direction of the felt so as to create an air curtain which lowers the pressure in a zone between the first and the second outlet, thereby maintaining the paper web on the felt as long as possible; and restricting air flow through the felt between a fourth cleft defined where the felt and the felt roll separate, and the second cleft.