In the engines with the conventional LO system, the authors have had some experiences that LO sludge went into the back side of the bearing metals and firmly stuck on them and that the bearing metals were pushed up from the back side and damaged by the sticking sludge.
Fig. 9 (a) is an example of a crank pin metal pushed up from back and damaged, and Fig. 9 (b) is the sludge sticking on the back side of the metal. Fig. 10 (a) and (b) are the enlarged views of the damaged part of the above metal and the sludge on the back.
As already shown in Fig. 8, the crank pin metal was very clean and free from any damages or scratches in case of the advanced FO・LO system because LO had been kept clean during the whole running period of the engine.
Fig. 9 Metal damaged by LO sludge on back
Fig. 10 Enlarged view of damage and sludge
5. FLUSHING FOR KIDNEY SYSTEM
The kidney system works only when the engines to be equipped with this system is clean. Therefore, those engines which have been in service for a long time and contaminated in LO itself and LO paths must be throughly cleaned before the kidney system is equipped with.
In our experience, however, the conventional engine flushing system hardly cleans engines. Our experiment made on a ship shows that only about 10% of the accumulated contaminant in engines is cleaned and eliminated by the conventional flushing. The authors, therefore, have deveploped a new flushing system E[4] which enables engines to be throughly cleaned within about two hours.
The outline of the process is as follows. (1) water is prepared which is by 3% volume of the total used LO volume. (2) A chemical called SR-30 is mixed into the Water prepared above. The volume of the chemical is 3% of the prepared water. (3) Then, the water mixed with the chemical is mixed into the used LO in LO tank. The chemical is a solvent for the accumulated contaminant on the LO flow path and in the crank case. (4)The engine is run at no lead for about two hours to circulate the LO and solve the accumulated contaminant into the used LO. (5)Some measurements are made to confirm that almost all the contaminant is washed and solved into the circulating used oil, (6) Finally, the used oil is renewed with fresh oil.
Fig. 11 shows an example. As is shown, n-P insoluble, toluene insoluble and water sharply increased in half an hour. However, n-P and toluene insoluble stopped increasing in half an hour of engine running. This was why almost all the contaminant was solved into the used circulating LO. The increased water of about 2% was due to the water which had been mixed into LO together with the SR chemical.
Our experiences show that used engines can be almost thoroughly cleaned about in half an hour. For the cause of safety, however, the standard flushing time is set to be 2 hours in this system.
Fig. 11 A new flushing
