ES341517A1 - Method and Apparatus for Drying Wet Paper Webs and Product Obtained with such Method. - Google Patents

Abstract

In apparatus for drying a wet web of paper fibres issuing at high speed from a papermaking machine, the web 35 is advanced by a roll 44 into contact with a foraminous surface, e.g. a flexible web 40, passing about a rotatably mounted foraminous shell 38 and advanced beneath a pressure hood 47 from which a heated gasseous fluid under pressure flows through the web into the interior of the shell in which a zone of reduced pressure is maintained as by an exhaust 53 connected to a vacuum source by a duct 54, the pressure drop pressing the web into contact with the foraminous surface. The pressure drop also forces the cellulosic fibres in portions of the web through aperture arranged in a predetermined pattern in the foraminous surface so as to shape the wet web either prior to or during the drying process, or the foraminous surface may have upstanding projections arranged thereon in a predetermined pattern and the fluid pressure is adapted to force the fibres, in portions of the web covering the projections out of the plane of the web and the plane of the foraminous surface. The pressure hood 47 may be subdivided by a partition 62 so that the fluid entering therein from ducts 51, 52 may be at different pressures. In other embodiments, (none shown): i) seal means formed by chambers in which air is maintained at the same pressure as the interior of the shell are positioned at the ends of the shell, Fig. 3. ii) the zone of reduced pressure is created by connection of the interior of the shell with a vacuum source through a hollow journal, Fig. 6, or apertures in one end wall of the shell aligning with a stationary duct. Fig. 7. iii) the flexible web 40 is not utilised, Fig. 8. iv) the rotary shell 38 is replaced by a single endless flexible web passing in a horizontal or inclined path between an upper pressure hood and a lower suction box or boxes, Figs. 9 and 10.