Size distribution of particulate emitted by a 6 MW industrial plant fueled with heavy oil and emulsion

The combustion of heavy fuel oil for power generation is a great source of carbonaceous and inorganic particle emissions, even though the combustion technologies and their efficiency are improving. The information about the size distribution function of the particles originated by trace metals present into the fuels is not adequate. In this paper, we focused our attention on the larger distribution mode of both the carbonaceous and metallic particles. Isokinetic sampling was performed at the exhausts of two heavy oil and heavy oil-water emulsion flames obtained in a 6 MWt pilot boiler. The samples were size-segregated by mean of an Andersen impactor. Further investigation performed on the samples using electronic microscopy coupled with X-ray analysis evidenced the presence of plerospheres, with typical dimensions ranging between 200 nm and 2-3 micron, whose atomic composition contains a large amount of the trace metals (Fe, V, Ni, etc). EDX analyses revealed that the metal concentration increases as the plerosphere dimension decreases. We also observed that the emulsion allow a drastic reduction of fine particles under certain combustion conditions.