Measuring Tangential Forces in a Pulp Refiner: A Novel Approach
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To get some insight into the processes that are active during the refining of wood, the tangential force distribution in the plate gap is of interest. Over the years several designs of force sensors have been developed for this purpose. One drawback with these designs is that each sensormeasures forces over quite a small area such that in order to cover the whole disc with a reasonably good resolution, many sensors have to be used. Also, there are problems to protect the active parts of the sensors from the harsh environment in the plate gap. In this paper a different concept is presented, in that the sensor is continuous and consists of a hollow radial bar equipped with strain gages on the inside. The force sensor was calibrated before mounting by loading it with a known load in the tangential direction and in different positions while measuring the strains in the points where the gages are located. This makes it possible to determine the so-called influence (or Green) functions. Knowing these it is possible to determine the tangential force distribution from strain values measured during operation of the refiner. Guidelines for doing this are presented together with a detailed description of the load sensor and some experimental results.
KeywordsPulp Refining Plate Gap Force Sensor Refiner Disc Strain Gages
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This work is part of the research project Filling the Gap and the authors acknowledge the financial support from the Swedish Energy Agency and VINNOVA. In addition, the authors are thankful for the support from project partners.
Lisbeth Hellström, PhD, is greatly acknowledged for reading through the manuscript and giving valuable comments.
- 1.Gradin, P.A., Johansson, O., Berg, J.-E., and Nyström, S.K., “Measurement of the Power Distribution in a Single Disc Refiner,” Journal of Pulp and Paper Science 25(11): 384–387 (1999).Google Scholar
- 2.Backlund, H.-O., Höglund, H., and Gradin, P., “Study of Tangential Forces and Temperature Profiles in Commercial Refiners,” Proceedings International Mechanical Pulping Conference, Quebec, Canada, pp. 379–386 (2003).Google Scholar
- 3.Senger, J.J., Siadat, A., Ouellet, D., and Wild, P., “Measurement of Normal and Shear Forces during Refining using a Piezoelectric Force Sensor,” Journal of Pulp and Paper Science 30(9): 247–251 (2004).Google Scholar
- 4.Olender, D.J., Forces on Bars in High-Consistency Mill-Scale Refiners, Ph.D. Thesis, University of Victoria, Canada (2008).Google Scholar