Particulate matter (PM) emitted from medium and large marine diesel engines contains a high quantity of soluble organic fraction (SOF) and sulfate compared with PM emitted from small high-speed diesel engines used in cars. For this reason the diesel particulate filter (DPF) used in cars are unsuitable for use in ships, because sulfate deteriorates the catalyst used in DPFs. In this study, the following experiments and analysis were carried out for the purpose of decreasing PM emissions from marine diesel engines that use heavy fuel oil and marine diesel oil. (1) The difference in the quantity (g/kWh) and composition (soot, SOF, sulfate) of PM emissions between small high-speed diesel engines and large low-speed marine diesel engines was examined. Using these results, the formation mechanism of PM for each engine was clarified. (2) To clarify the effect of DPF on PM reduction, the filter material used in DPF was installed between PM sampling probes set in the exhaust lines of test engines and dilution tunnels. The components of the PM with and without the filter material were compared. (3) Finally, guidelines for PM reduction were discussed based on this analysis, and their effectiveness was verified in actual engines and ships.
