Emissions of polycyclic aromatic hydrocarbons from a domestic pellets-fired boiler

•Emissions of PAHs from a domestic pellets-fired boiler were evaluated.•Boiler fired with pellets of pine sawdust, cork residues and kiwi residues.•Pine sawdust and cork residues yield lower total PAH emissions than kiwi residues.•PAH emissions increase with thermal input for pine sawdust and cork residues.•PAH emissions decrease with thermal input for kiwi residues. This work evaluates the emissions of polycyclic aromatic hydrocarbons (PAH) from a domestic pellets-fired boiler. Three biomass residues, pine sawdust, cork residues and kiwi residues, were used in this work. The experiments were carried out at three boiler thermal inputs (10, 14 and 17 kW). The PAHs were collected from the flue gas using a resin (XAD-2) placed inside a narrow tube, located after a quartz microfiber filter that collected the particulate matter, including soot, present in the boiler combustion products. Subsequently, the PAHs were analyzed and quantified combining Soxhlet extraction and gas chromatograph-mass spectrometry. In addition, for each test condition, flue gas concentrations of O2, CO2, CO, hydrocarbons and NOx were also measured to monitor the boiler operation. The results showed that pine sawdust and cork residues firing yielded lower total PAH emissions than kiwi residues firing, and that PAH emissions increase with the increase of the boiler thermal input for pine sawdust and cork residues firing, but decrease for kiwi residues firing. The present PAH emission data are in line with the limited data reported in the literature, and emphasize the need to extend the current data base to encompass other biomass residues, including non-woody residues.