Methods for Analysing Paper Machine Efficiency

Calculation of paper machine efficiency is used to analyze and benchmark operational performance of paper machines. It is one of the factors affecting the profitability of the papermaking line. Efficiency can be described as the first-pass retention figure for saleable paper on a paper machine. This figure has a great impact on financial performance, where sales price, fixed and variable costs with sufficiently high efficiency, are optimized. There are several ways to perform efficiency comparability. Due to the variety of existing methods, the main objective of this study was divided to three sub goals: (1.) identify, analyze and understand the discrepancies in line efficiency calculation rules currently in use, (2.) to make recommendations on how to improve and harmonize them and (3.) create more precise calculation methods. The theoretical part of this study focused on understanding of the currently available methods for efficiency calculations. The industrial practices part presents methods and knowledge that have been dominated the industry for decades. Moreover, this part outlines the presentations and internal articles from the companies that have been adopted as daily practice in the industry. The existing methods are mainly tactical, relative and history-based methods. As the tools, have been in tactical use, the industry has learned to reach close to 100% line efficiencies. In the new, novel approach the full efficiency capacity of a paper machine splits the efficiency into three operational horizons: tactical, strategic, and normative and three dimensions of its information: detailed, relative and absolute. This matrix allows the users to identify the method according to the decision need. All the methods were simulated on different types of paper machines, from newsprint to double-coated fine paper due to the modularity of the calculation methods. This study provided the basis for the creation of a new, more focused global guideline. It was created in co-operation with papermakers and machine suppliers from the Zellcheming paper technological committee during 2003-2005. A new Zellcheming Merkblatt III -guideline was published based on this study at the beginning of 2005. This work clearly points out the need for more precise methods to analyze efficiency. The new guideline and this study creates a platform which facilitates more detailed efficiency analyses and calculation of efficiency more precisely from mill to mill. It gives us a more accurate base for benchmarking, for improved target setting, for measuring actions and for making easier decision-making.