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Using miniature diode array NIR spectrometers for analysing wood chips and bark samples in motion

2000; Wiley; Volume: 14; Issue: 5-6 Linguagem: Inglês

10.1002/1099-128x(200009/12)14

1099-128X

Lars Axrup, Karin E. Markides, Torsten Nilsson,

Mineral Processing and Grinding

The chemical and physical properties of the wood chips entering the Kraft pulping process are of high interest for many different reasons. The most important one is the possibility to establish an effective and dynamic forward process control. The same is valid for one of the by-products, bark, which is burned in a solid fuel furnace for energy recovery. In the present study, NIR (near-infrared) reflectance measurements with an inexpensive silicon diode array spectrometer operating in the 800–1100 nm range are evaluated as a tool for on-line analysis of wood chips and bark transported on a conveyor belt moving at 1 m s−1. The objective of this work was to investigate the determination of water content, extractive content, Klason lignin, carbohydrate monomers and size distribution of wood chips together with water content, wood content and coarseness of bark. All these parameters could be measured with the exception of the carbohydrates, for which it was only possible to satisfactorily measure the sum of pentoses (arabinose + xylose) and the sum of hexoses (glucose + galactose + mannose). FWEFA (fixed window evolving factor analysis) was used for automatic identification of outliers. Copyright © 2000 John Wiley & Sons, Ltd.