Impacts on X-ray fluorescence measurements for rapid determination of the chemical composition of renewable solid biofuels

Abstract

Rapid determination of quality parameters in solid biofuels enables transparent fuel trading and optimised plant operation, e.g. due to lower plant operating costs and lower air pollutant emissions. The present study investigates the impact of interferences caused by the chemical composition, particle size, water content, and measuring time on the rapid measurement technique X-ray fluorescence analysis for solid biofuels. The elements investigated are the minor elements Na, Mg, Si, P, S, Cl, K, Ca and the trace elements Al, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, As Cd, Pb as described in ISO 17225-1. The results provided new insights into the cause of measurement errors and also similarities with findings from other fields. Specifically, we found that grain size <1 mm in sample preparation and water content ≤10 % had a clear benefit on the measurement. In the case of samples with high mineral content, interferences between the elements Si and P occur. Furthermore, the results show that the measurement time for the actual measurement can be significantly reduced to 60 s compared to the factory setting (i.e. from 750 s). The findings of the study contribute to reducing or preventing the indicated measurement errors in future XRF analysis.