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

- A new X-ray method for measuring moisture-, ash content and heating value of biofuels is proposed.
- The method is a combination of X-ray transmission and fluorescence-qDXA-XRF.
- The qDXA-XRF measures 0.5-1.5 kg samples with an analysis time of 1 min.
- The qDXA-XRF can be generalized to on-line measurements on e.g. conveyor belts.

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.