Performance of a household boiler fed with agropellets blended from olive mill solid waste and pine sawdust

The main purpose of this present work is to study the combustion characteristics of a domestic boiler (12 kW) when fired with biofuels prepared by blending an industrial by-product (pine sawdust, PS) and an agro-industrial by-product (Olive Mill Solid Waste, OMSW). The boiler and combustion efficiencies as well as gaseous emissions were determined and compared to EU normalization standards (EN 303-5). It was found that the main exhaust gases (CO, CO2 CxHy and NOx) are emitted in acceptable concentrations comparing to other biofuels in the literature. The analysis of bottom ash compositions shows the presence of three oxides, namely CaO, K2O and SiO2 as well as a significant amount of unburned carbon. Hence, the boiler control through the primary and secondary air injections should be adapted to the different pellets properties. Additionally, both combustion efficiency and boiler efficiency results are encouraging for considerations of prepared agropellets as alternatives to woody biofuels.