Evaluation\nand Optimization of an X‑ray Fluorescence\nAnalyzer for Rapid Analysis of Chemical Elements in Solid Biofuels

To optimize wood-fired\nheat (and power) plants, it is\nessential\nto rapidly determine the chemical composition of solid biofuels on-site\nshortly before combustion. However, the standard procedures for chemical\nanalysis [inductively coupled plasma-optical emission spectrometry\n(ICP-OES), inductively coupled plasma-mass spectrometry] are time-consuming,\nexpensive and require highly trained personnel. Thus, they are unsuitable\nfor online fuel analysis. Newly developed, rapid, on-site analysis\nmethods might enhance analysis at the plant. Thereby, X-ray fluorescence\n(XRF) analysis is one of the most promising methods. So far, XRF has\nbeen evaluated in various fields like geology, coal, ash analysis,\nas well as biomass in general, but this method is still insufficiently\ninvestigated for the sector of solid biofuels. The aim of this work\nis to evaluate and optimize an XRF analyzer for the rapid determination\nof chemical elements in wood fuels. The XRF analyzer was calibrated\nusing several wood chip samples. Measurements before and after calibration\nwere compared with the reference method (ICP-OES). Results show that\nXRF can be recommended for analyzing the elements Mg, P, K, Ca, Si,\nAl, Cr, Mn, Fe, Zn and Pb, while S, Cl, Ti and Ni can potentially\nbe determined with element-specific calibrations. Cu, As, and Cd could\nnot be measured satisfactorily, as many measurements were below the\nlimit of detection. Still, XRF might be used for threshold value monitoring\n(e.g., in the scope of the German Waste Wood Ordinance).