Practical Application of Transfer Belts for Closed Draw Sheet Transfer at High Speeds, 2001 Papermakers Conference Proceedings

The closed draw concept for paper machines has been discussed over the years and patents exist describing this concept dating from 1982. Much development work has been completed by Albany International and Valmet and has been reported previously [1]. Modern high speed paper machines today reach speeds of around 1800m/min on a regular basis, and at these speeds, high stresses are placed on the wet web with higher strength being required today in these modern press sections. The open draw between the press section and the dryer section was the limiting factor before in consistently achieving these speeds or higher. Using a belt to transfer the sheet between sections has closed this gap, the sheet can now be supported all the way from the wire section to the calender. The transfer belt has unique properties regarding runnability, quality aspects and economics when handling a paper web through a press nip and transferring the paper web to a dryer fabric. This paper will cover the practical experience seen to date in running these belts.