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Proceedings Paper

Pulsed laser photoacoustic monitoring of paper pulp consistency
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Paper Abstract

This study involves measurements of pulp consistency in cuvette and by an online apparatus, by innovatively scattering photoacoustic (SPA) method. The theoretical aspects were described at first. Then, a few kinds of wood fiber suspensions with consistencies from 0.5% to 5% were studied in cuvette. After that, a pilot of online apparatus was built to measure suspensions with fiber consistency lower than 1% and filler content up to 3%. The results showed that although there were many fiber flocks in cuvette which strongly affected the measurement accuracy of samples consistencies, the apparatus can sense fiber types with different optical and acoustic properties. The measurement accuracy can be greatly improved in the online style apparatus, by pumping suspension fluids in a circulating system to improve the suspension homogeneity. The results demonstrated that wood fibers cause larger attenuation of acoustic waves but fillers do not. On the other hand, fillers cause stronger scattering of incident light. Therefore, our SPA apparatus has a potential ability to simultaneously determine fiber and filler fractions in pulp suspensions with consistency up to 5%.

Paper Details

Date Published: 5 June 2008
PDF: 8 pages
Proc. SPIE 7022, Advanced Laser Technologies 2007, 70220D (5 June 2008); doi: 10.1117/12.803917
Show Author Affiliations
Zuomin Zhao, Univ. of Oulu (Finland)
Matti Törmänen, Univ. of Oulu (Finland)
Risto Myllylä, Univ. of Oulu (Finland)


Published in SPIE Proceedings Vol. 7022:
Advanced Laser Technologies 2007

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