Review of factors affecting the release of water from cellulosic fibers during paper manufacture

Abstract

The ease with which water is released from cellulosic fiber material during the manufacturing of paper can affect both the production rate and the consumption of energy during the manufacturing process. Important theoretical contributions to dewatering phenomena have been based on flow through packed beds of uniformly distributed fibers. Such descriptions are able to explain why resistance to dewatering increases as a function of the hydrodynamic surface area of fibers. More recent studies have demonstrated a critical role of finely divided matter. If the fines are unattached to fibers, then they tend to move freely through the fiber mat and plug channels in the paper web during the dewatering process. Dewatering also is affected by the deformability of cellulosic fibers and by whether the fibers easily slide past each other, thereby forming a dense mat. By emphasizing the role of fine matter, colloidal forces, and conformability of cellulosic materials, one can gain a more realistic understanding of strategies that papermakers use to enhance initial drainage and vacuum-induced dewatering.

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

“…In light of that situation, one can understand why a lot of attention has been paid to increasing the rate and extent of wet-end removal of water by the use of chemical additives. The nature of these additives, as well as their mechanisms of action, have been covered in earlier reviews (Lindström 1989;Hubbe 2005;Hubbe and Heitmann 2007;Hubbe and Dölle 2018). Briefly stated, the additives work by combinations of coagulation (related to charge interactions), polymer bridging, and polyelectrolyte complexation.…”

Process simulation-based evaluation of design and operational implications of water-laid paper machine conversion to foam technology

“…Dewatering in conventional papermaking is widely studied and quite well understood (Baldwin 1997;Hubbe and Heitmann 2007;Åslund and Vomhoff 2008). However, the dewatering of foam differs considerably from the dewatering of water.…”

Electroassisted Filtration of Microfibrillated Cellulose: Insights Gained from Experimental and Simulation Studies

“…Electroassisted filtration of cellulose in the form of microcrystalline cellulose (MCC) has been investigated by Wetterling et al, , who showed it to be an efficient method with an energy demand that was not only reasonable but also lower than that of thermal drying. Although MCC and MFC are both cellulosic materials, their inherent characteristics related to particle morphology and flexibility may give rise to different filtration behaviors, for example, in terms of the filter cake structure . MCC has a cylindrical shape and high crystallinity, which make them rather stiff, whereas MFC has a much larger aspect ratio and contains both crystalline and amorphous regions, which make them flexible.…”

“…Although MCC and MFC are both cellulosic materials, their inherent characteristics related to particle morphology and flexibility may give rise to different filtration behaviors, for example, in terms of the filter cake structure. 30 MCC has a cylindrical shape and high crystallinity, which make them rather stiff, whereas MFC has a much larger aspect ratio and contains both crystalline and amorphous regions, which make them flexible. These differences, along with those related to surface charge, confer special properties to the viscosity and stability of the respective suspensions.…”