Application of optical fluorescence spectroscopy to paper production

• Fluorescence light emitted from paper following the absorption of either ultraviolet or visible light has a wavelength distribution determined by the chemical composition of the paper. This can be used both for laboratory measurements of paper characteristics and for on-line monitoring of the paper during production. Such measurements can be performed non-intrusively at sampling rates high enough to give a sub-millimetre resolution in the machine direction in a paper machine or rerewinder. In this project two types of fluorescence monitors have been constructed. They are operating at different wavelengths and thereby they monitor different substances in the paper. The monitors have been tested at newsprint producing paper mills together with an optical speedometer. The measurements in the production environment have shown that the equipment is capable of indirectly monitoring paper quality parameters which affect the local abundance of lignin. Examples of such parameters are the number of shives in the paper and wire marks. A fluorescence based method for scanning cross-directional newsprint profiles in the laboratory has been developed. From these measurements the relative shrinkage of the paper during drying can be calculated using time-frequency analysis.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Materialteknik -- Pappers-, massa- och fiberteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering -- Paper, Pulp and Fiber Technology (hsv//eng)

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