Effects of biomass co-firing with coal on ash properties. Part I: Characterisation and PSD

The alterations of ash quality and utilisation aspects when co-firing coal with biomass were investigated. Co-combustion tests were performed in lab and semi-industrial scale facilities, using several coal–biomass blends. The collected ash samples were analysed for major elements and heavy metals content, loss on ignition (LOI), free CaO content and grain size distribution. Since a variety of co-combustion residues were tested, important implications concerning the ash composition and, consequently, its further use in potential applications came up. Results showed that properties of co-combustion residues are directly connected to the combustion conditions and the individual blend components. Biomass exploitation as secondary fuel in co-combustion processes is technically and economically feasible up to 20% w/w and the produced ash could be further utilised without any major treatment.