Sizing and characterization of particulate emissions from heavy fuel oil spray combustion

Chemical and spectroscopic characterization of fine particles fraction (< 1micron) collected in the last stage (backup filter) of an Andersen impactor has been performed in flame and at the exhaust of a 100 kW spray burner burning heavy fuel oils having a different content of asphaltenes and aromatics. The fine particulate was extracted in dichloromethane (DCM) for the analysis of soluble organic material by gas-chromatography-mass spectrometry (GC-MS), size exclusion chromatography (SEC) and UV-visible absorption and fluorescence. The residual particulate material insoluble in DCM was treated in a very polar and powerful solvent as N-methyl-pyrrolidone (NMP) that is able to dissolve and/or to get stable suspensions of soot, allowing their analysis by means of techniques generally applied only on liquid samples, as SEC and UV-visible absorption and fluorescence spectroscopy. SEC technique has allowed to evaluate a distribution of molecular masses and UV-visible absorption and fluorescence spectroscopy applied on DCM and NMP solutions of samples allowed to investigate similarities and differences in the chemical structure and in particular on the aromaticity of the particulate materials collected in the smallest dimensional ranges (< 1micron).