Browse Publications Technical Papers 2004-01-1887

Impact of Oil-derived Ash on Continuous Regeneration-type Diesel Particulate Filter - JCAPII Oil WG Report 2004-01-1887

Impact of oil-derived ash on the pressure drop of continuous regeneration-type diesel particulate filter (CR-DPF) was investigated through 600hrs running test at maximum power point on a 6.9L diesel engine, which meets the Japanese long-term emission regulations enacted in 1998, using approximately 50ppm sulfur content fuel. Sulfated ash content of test oils were varied as 0.96, 1.31, and 1.70 mass%, respectively. During the running test, the exhaust pressure drop through CR-DPF was measured. And after the test, the ventilation resistance through CR-DPF was also evaluated before and after the baking process, which was applied to eliminate the effect of soot accumulated in CR-DPF.
The results revealed that the less sulfated ash in oil gave rise to lower pressure drop across CR-DPF. According to microscope examination of the baked DPF, ash was mainly accumulated on the wall surface of CR-DPF, and that seemed to be related to the magnitude of pressure drop caused by ash. The main component of ash on CR-DPF was CaSO4, of which Ca is derived from oil.
Metal content in exhaust gas was also analyzed at the engine out. It was found that Ca content at the engine out had increased proportionally with Ca content in oil. Furthermore, when compared at engine out and behind CR-DPF, it was found that over 95% of oil-derived metal in exhaust gas could be trapped by CR-DPF, irrespective of exhaust gas condition (flow rate and temperature) and oil additive formulation.
The oil with less sulfated ash can reduce the accumulation of oil-derived ash on DPF, and thus the pressure drop through DPF. Therefore, it will contribute to prolong the maintenance interval of the DPF.


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