PAPER PHYSICS. The web structure in relation to the furnish composition and shoe press pulse profiles during wet pressing

Abstract

This study shows that wet-pressing TMP and DIP with a shoe press pulse may yield similar afterpress solids, provided that an adequate shoe pulse length with similar pressure profile is applied. A wet web with more porous structure in the sheet dewatering (felt) layer seems to contribute to the increased dewatering during wet pressing. In addition, a shoe press pulse with high peak pressure at the end yields higher solids content after wet-pressing and higher bulk compared to a pulse with a peak pressure in the beginning. The increased dewatering during wet-pressing implies a reduction of steam consumption in the dryer.

Prospects for Maintaining Strength of Paper and Paperboard Products While Using Less Forest Resources: A Review

“…Increased production rates when using extended nip presses have motivated developmental efforts, as well as some key publications (Pikulik 1999;Schlegel and Kaipila 2002;Lange and Meitner 2006;Hii et al 2012). Danielsson (2002), among others, has reported that the structure of the press felt can have a major impact on the results achieved in an extended nip press.…”

“…Danielsson (2002), among others, has reported that the structure of the press felt can have a major impact on the results achieved in an extended nip press. Hii et al (2012) showed that there can be an advantage achieved by designing a press nip such that the sheet experiences increasing pressure almost to the point of exit. Such a profile of applied pressure was found to achieve not only higher solids of the emerging web, but also higher bulk in the resulting paper.…”

Energy efficiency challenges in pulp and paper manufacturing: A tutorial review

“…Not only does the longer nip help to overcome the constraints of flow (Hubbe et al 2020), but it also can permit optimization of the pressure profile. Thus, the pressure can be "ramped up" even within a single nip (Hii et al 2012). This is in keeping with a time-testing strategy of gradually increasing the intensity of water-removal measures throughout the paper machine system.…”