Advanced Use of Slotted Screens for Protection of the Paper Machine, 2000 Papermakers Conference Proceedings

May Fursey--Within the production of fine paper grades, contamination continues to be a major problem. Our society continues to use more and more plastic for packaging and wrapping of products. This plastic inevitably finds its way into the paper mill and eventually into the pulp stream. The introduction of recovered paper (recycle) presents further product quality and paper machine runnability problems. This paper discusses the options for protecting against contamination which can cause such problems as coating streaks and scratches, pinholes, sheet breaks and other runnability issues on the paper machine. These defects lead to loss of production due to customer complaints as well as direct losses at the producing mill due to excessive waste and down time. There are basically two options for protecting the paper machine from contamination. They include: 1) slotted screens being installed in the thick stock system prior to the machine chest, and 2) slotted screens installed directly in the paper machine approach flow system.