Re-Visiting PM Efficiency: Practical Applications of the Impact of Web Instability at the Open Draw in Mill Case Studies

摘要

Paper machine efficiency is mostly affected by machine down time, resulting from maintenance work and paper breaks. One of the main factors affecting paper breaks is web instability at open draws. Web instability can originate from different sources, from paper properties variations to paper machine equipment to pulp quality. Often, the root cause of the instability can be difficult to identify because of the lack of information or tools that could help in understanding the relationship between web instability at open draws and paper breaks. In order to explore this, a set of tools was developed to quantify the variability of some of the key parameters at open draw, such as release point, moisture and draw. Case studies are presented to show how these innovative tools were used in mills to assess variability of these key parameters, before and after changes on paper machines such as a new press cover, drive modifications or steam box installation. More importantly, links could be made between reduced variability at open draws and the amount of breaks following these changes.