User's Request to Marine Fuel Oil
Haruo MIYANO *
Although it is difficult to figure out the fuel oil quality, it is apparent that fuel oil, which contain more than 20% of MCR, more than 0.1% of TSE, so called dumb-bell fuel oil, can be direct cause of engine troubles. Changes of the fuel oil quality through the pre-treatment system was investigated and found;
1) Al+Si, water, sediments etc. can be removed somewhat well by purifiers,
2) manufacturer's recommendation for purifier's capacity is workable for the normal fuel oil (around 20 mg/kg of Al+Si), and is insufficient for 80 mg/kg of Al+Si (ISO RM).
Author hopes for:
1) active control over the degrading of fuel oil and stabilization of the quality,
2) higher reliability of engines and designation of the fuel oil's qualities,
3) introduction of common testing methods for pre-treatment system
4) introduction of the safety concept into ISO 8217 and CIMAC recommendation.
Key Words: Problem by fuel oil, TG-DTA, Dumb-bell fuel, purifier, separation efficiency, ISO 8217
Marine engine system is quite different from the others by reason that the users must participate with the system much more than any other system.
This paper aims to introduce a part of problems related to fuel oil and the investigated results on the on-board pre-treatment system. Then, the user's concerns with marine fuel oil will be described.
2. PROBLEMS CAUSED BY FUEL OIL
Troubles related to fuel oil can be divided into two categories, which are the ones of pre-treatment system and of combustion system. It is not so difficult to mention about the former, such as choking of filters, abnormal sludge generation, etc. Because these troubles occur without time delay and the phenomenon can be seen directly.
On the other hand, although we have been analyzing marine fuel oil for many years to protect engine system form troubles, it is very difficult to identify the cause(s) of the trouble in combustion system. Because fuel quality, engine types and load, degree of maintenance, cylinder oil characteristics, etc. influence the troubles, and sometimes they occur with time delay, and phenomenon is unable to see directly.
This paper aims to outline the characteristics of fuel oil, which have potential problems to marine engines.
2.1 PROBLEMS OF COMBUSTION SYSTEM
The correlations between CCAI and MCR (Micro Carbon Residue) of fuel oil are shown in Fig.1 and 2. The former indicates a distribution of normal fuel oil and the latter for fuel oil that caused combustion troubles.