Press section for the extraction of water from a wet web, or paper or tissue or cardboard, sets the dry content at a raised level at the edges in and/or before the press section to increase the web stability

摘要

At the press section of a papermaking or tissue or cardboard production machine, the dry content is raised at the edges of the web (1) in comparison with the remainder of the web, in and/or before the press section, to increase the web stability. To increase the web stability at the press section of the machine, the dry content of the web is increased steadily towards the edges. After the press section, the dry content of the web edges is reduced and/or the dry content is increased at the center of the web. An even moisture content profile is set at the web after the press section, and preferably at a following drying station. The residual moisture profile is measured at the web at the end of the press section or at the start of the following drying station, to set the adjustments to the dry content of the web at the edges and/or the center. An Independent claim is included for the press section of a web production machine, where the dry content at the web edges is increased in and/or in front of it by a heater (3) at the edges of the web or the blanket (2). A conditioning station (4) for the blanket gives blanket edges which are dryer than the center of the blanket. At the press section, an increased pressure is applied by the press cylinders at the edge zones of the web. At the following drying station, the center of the web is heated more strongly than the edges. A monitor (13) measures the web residual moisture profile at the end of the press section, or at the start of the drying station, linked to a wetting unit (5) and/or a drying unit (7) to adjust the moisture content level.