Rapid X-ray based determination of moisture-, ash content and heating value of three biofuel assortments

Abstract

Here we demonstrate a new hyphenated X–ray method, qDXA–XRF, for the simultaneous determination of moisture–, ash content and heating value (as received) of biofuels. The method is based on the combination of X-ray transmission imaging and X–ray fluorescence spectroscopy.The method performance is demonstrated using three biofuel assortments; logging residues, roundwood chips and sawdust, on approximately 3 L samples (∼500–1500 g) with a total analysis time of one minute per sample.Mean absolute errors for the logging residues, roundwood chips and sawdust determinations respectively were; for moisture content MAE = 0.034, 0.026, 0.011 (wet basis mass fraction), for ash content MAE = 0.0015, 0.0015, 0.0049 (dry basis mass fraction), and for heating value (as received) MAE = 0.55, 0.44, 0.17 MJ kg−1.Furthermore, for the assortment logging residues, the qDXA–XRF determination of heating value decreases the measurement uncertainty from MAE = 1.53 to 0.55 MJ kg−1 (∼60% decrease) compared with traditional oven moisture/equation method.