Press unit to extract water from a wet web, at a press section, has a unit to remove water from a press roller surface and a wetting unit for the roller to set the lateral moisture content profile of the web

摘要

The press unit at a press section to extract water from a wet web (1), of paper or cardboard or tissue and the like, has a press gap between two rollers (4,5) where the web is carried through with at least one continuous blanket (2,3). A water removal unit (6) is at least at one roller surface, after the press gap, to detach clinging water, followed by a wetting unit (7) to affect the lateral moisture content profile of the web. The web press section has a wetting unit for the press roller surface, where the volume of water is controlled in separate zones across the web width according to any deviation between the measured web lateral moisture content profile and the required profile. The roller wetting unit has a number of spray jets (8), across the web width, to spray steam and/or water at the roller surface as close to the roller press gap as possible. The press roller with the surface wetting unit has a continuous blanket passing over it, and its mantle surface is profiled, preferably by blind drillings and/or ridges. The unit to detach water from the roller surface has at least one scraper (9), together with a suction unit (10) to extract the removed water. Both press rollers each have a continuous blanket at them, and each has a unit to detach water from the roller surface and a unit to wet the surface. The press gap between the rollers is extended, with a flexible roller mantle (11) at least at one press roller and preferably the roller over the moving web.