Web roller press station has a water extraction system with a suction channel aligned at the press blanket to pick up extracted water to be passed to a collection vessel for disposal

摘要

At the press station to extract water from a wet paper/cardboard/tissue web (1), where it is pressed in the gap between two rollers (2,3), a water pick-up unit (5) has at least one suction channel (6) extending into the wedge gap between the upper roller (2) and the press blanket (4). The channel (6) extends across the web width, and is connected to an underpressure source. The suction channel (6) has a gap width of 1-50 mm, at least at the leading zone, and pref. 2-7 mm. The underpressure at the leading zone of the suction channel (6) is 50-80000 N/m2> and pref. 10000-30000 N/m2>. The suction channel (6) leads to a collection vessel (7) to hold the extracted water and deliver it away from the press station. The outlet opening (8) from the suction channel (6) is over the max. water level in the collection vessel (7). The underpressure connection (9) is at the collection vessel (7), over the max. water level. The suction channel (6) is defined by an upper (10) and a lower (11) wall, across the web (1) width. The channel walls (10,11) are aligned at an acute angle to the press blanket (4), at least at the leading zone. The leading edge (12) of the lower channel wall (11) is as close as possible to the press blanket (4), with a gap between them pref. =20 mm. The leading edge (12) of the lower channel wall (11) can be in contact with the press blanket (4), and even press into it. The leading edge (12) of the lower channel wall (11) is formed by a wear-resistant bar (13), which forms an included angle of 10-45[deg] with the press blanket (4). The upper wall (10) of the suction channel (6) is a component part of the water trap unit (14) which catches water spray from the upper press roller (2) over the suction channel (6). The position of the leading edge (15) of the upper suction channel wall (10) can be shorter than the lower wall edge (12), in the roller gap, at the same position or deeper into the roller gap. The water collection vessel (7) is divided into chambers, across the web (1) width, each with a connection (9) for the underpressure source.