Papermaking machine based on double sieve conveyors and balanced, constant pressure de-watering, includes additive supply unit with controller varying volumetric flow and pressure

摘要

The additive supply unit (21) has a controller varying the volumetric flow and pressure of the additive. Preferred features: The supply unit has a connection for admixture of e.g. compressed air or steam. It is located near the start or the central region of the dewatering zone. Following the supply unit there is a balanced pressure, reduced-intensity dewatering section, e.g. its plate is non-perforated. The supply unit extends over the band width, divided into several sections, each individually controlled to discharge a fraction of the additive. They have moving cleansing units. Spacing between successive dewatering sections (16A, 16B) is variable. In the double band zone, against one porous band, there is a porous plate dewatering section, opposed to strip formations on the opposite side of the double band. Strip widths and/or their spacing vary. Plate and/or strips are pressed flexibly against the double band.