Partitioning of K, Cl, S and P during combustion of poplar and brassica energy crops

K-, Cl-, S- and P-release from a herbaceous (brassica) and a short rotation coppice (poplar) cultivated in the Mediterranean region, have been investigated under combustion conditions 1500-1100 degrees C]. Contrary to brassica, Cl- and S-release from poplar were substantial for all temperatures tested. Low-temperature 1500-700 degrees C] Cl-release from the high-Cl brassica appeared to be primarily limited by the fuel chemical composition and secondarily by interactions of the ash-forming elements with the fuel organic matrix. Below 700 degrees C, Cl-release was nearly 50%, whereas complete dechlorination resulted around 800 degrees C. S-release from brassica was up to 40% at low temperature. Above 1000 degrees C, additional S-release was observed presumably by sulfate dissociation. K-release was linked to Cl-release around 700 degrees C and, gradually increased afterwards. At 1100 degrees C, nearly 60% of K in poplar was retained, whereas around 40% of K and S remained in brassica ash. P-release was not significant for both energy crops at tested conditions. (C) 2014 Elsevier Ltd. All rights reserved.