Rewetting after high vacuum suction boxes in a pilot paper machine
2015 (English)In: Nordic Pulp and Paper Research Journal, ISSN 0283-2631 (print), Vol. 30, no 4, 667-672 p.Article in journal (Refereed) Published
Increased energy efficiency is a major concern for all companies today. Not only does the cost efficiency follow energy efficiency but also environmental and sustainability aspects motivate more energy efficient production lines. A study has been made on a pilot paper machine with the purpose to show the magnitude and time of rewetting after high vacuum suction box dewatering. The grammages used in this study were 20 and 100 g/m2 to cover both tissue and printing paper grades. Machine speed was varied from 400 to 1600 m/min and the maximum pressure drop in the suction box was 32 kPa. The pulp used was unbeaten, chemical, fully bleached softwood from Sweden.
Rewetting is observed when the dewatering in the suction box is sufficiently high. No rewetting takes place when the dewatering in the suction box is limited due to insufficient pressure drop and dwell time. The time for the rewetting is in the range of 10-50 ms and in this study the maximum rewetting observed is 180 g/m2, or 6.1% decrease in dryness. The mechanisms behind the phenomenon are believed to be capillary forces caused by sufficiently low sheet moisture and expansion of the network.
This study shows that rewetting is so fast that it would be difficult to prevent it without changing major machine parameters.
Place, publisher, year, edition, pages
2015. Vol. 30, no 4, 667-672 p.
Rewetting, Suction box dewatering, Forming fabric, High vacuum, Pilot study, Energy efficiency, Paper forming
Research subject Chemical Engineering
IdentifiersURN: urn:nbn:se:kau:diva-47565OAI: oai:DiVA.org:kau-47565DiVA: diva2:1062838