The role of evaporative dewatering in impulse pressing
2003 (English)In: TAPPI Journal, ISSN 0734-1415, Vol. 2, no 3, 26-32 p.Article in journal (Refereed) Published
The objective was to link heat transfer to water removal mechanisms, specifically evaporative dewatering, in impulse pressing experiments. Two independent laboratory devices-a platen press and a shoe press-were used to impulse press fiber webs made from softwood bleached kraft (SBK) over a range of basis weights (20 200 g/m(2)). In the platen press experiments, evaporative dewatering was evaluated by comparing the measured heat input to the amount of heat theoretically required to vaporize the water in excess of unheated wet pressing. Evaporative dewatering was found to be most pronounced for lightweight sheets, and enhanced dewatering can be attributed to this mechanism and other high-temperature mechanisms for basis weights above 60 g/m(2). In the shoe press experiments, a composite sheet of five 30-g/m(2) webs was used to evaluate profiles for resulting dryness, density, and water retention value (WRV) in the thickness direction. Evaporative effects were confined principally to the layer directly in contact with the heated surface.
Place, publisher, year, edition, pages
2003. Vol. 2, no 3, 26-32 p.
water removal, heat-transfer, paper webs, unit
IdentifiersURN: urn:nbn:se:kth:diva-22517ISI: 000183008400006OAI: oai:DiVA.org:kth-22517DiVA: diva2:341215
QC 201005252010-08-102010-08-10Bibliographically approved