In connection with the standardization of marine-use fuel oil (International Standard ISO 8217) into JIS standard, inquiries on the selection of oil purifiers and also on the separating efficiency of FCC catalyst fines are increasing. From the viewpoint of purifier manufacturer, important points in selection and operation of purifiers for low grade heavy fuel oil are explained here. Also Westfalia Separator's treatment system for low grade heavy fuel oil etc. are introduced.

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In recent years failures of marine diesel engine shows a tendency to increase. Especially abnormal wear of piston ring and cylinder liner is serious problem.
Therefore role of fuel oil treatment system for marine diesel engine is becoming important every year.
Ability of fuel oil treatment system is affected by fuel oil properties, construction of system, ability of individuality, condition, and operation method.
So we investigated actual ability of fuel oil treatment systems by analyzing fuel oil that collected from each tereatment devices.
The result of investigation is be shown as follows.
The main item of properties that bring engine failures are water, sulfur, Carbon Residue, FCC catalyst, Asphaltene, Dry Sludge, Vanadium, Sodium, etc.
Then Water, FCC catalyst, and Dry Sludgein are removed by Fuel oil Treatment System.
Average ratio that purifier removed FCC catalyst was 43.2%. Average flow ratio was 50.1%. And this was affected flow ratio of fuel oil.
Fuel oil treatment devices do not always give enough ability. And ability of treatment is given influence by method of operation.

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The latest heavy based oil for marine fuel oil tends to become heavier and inferior quality, for catalytic cracker or thermal cracker operates owing to increase of demand of gasoline and gas oil.
On the other hand, still there are reports regarding with engine troubles which are caused by inferiority of ignition, combustibility and stability of the marine fuel oil.
With regard to ignition and combustibility of marine fuel oil, it is difficult to judge from the results of standard analysis; consequently reports of special analysis of every kind are published.
Under such a condition, we found out the knowledge to make sure of combustibility and stability of marine fuel oil by measuring the absorption value on methyl and methylene group which are included in the fuel oil.

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Experimental research was performed to determine the combustion performance of marine fuels using thermogravimetry-differential thermal Analysis (TG-DTA) and the fuel droplet combustion method. The results made it possible to distinguish between normal fuels and fuels which used combustion problems. It was found that the probability of combustion failure was high when the fuel has the following characteristics:
(1) Large asphaltene content
(2) Small ratio of carbon residue to asphaltene
The structures and combustion characteristics of carbon residues generated from the components of several kinds of residual fuels were analyzed using X-ray diffraction, elemental analysis, and thermal analysis. The resuls showed that the carbon residue generated from the asphaltene component had the worst combustion characteristics.

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I have worked for S.E.M.T.Pielstick Engines with plesure since more than 30 years ago but had various engine trouble and made the possible efforts to investigate their causes and to take measure to improve such a situation for a long time.
I have found that the big troubles were caused by deterioration of lublcant due to less capacity of lube oil purifiers and then it seems to be most important for the medium speed engines to keep the good characteristic of lubricant by increasing the capacity of lube oil purifiers. I am pleased to explain the good results by increasing the capacity of lube oil purifiers hereafter.
On the other hand, the fuel oil quality has much influenced the engine performance and then the enough fuel oil purification must be considered with the good lubricant condition by adoption of large capacity of lube oil purifiers in expectation of the deterioration of fuel oil quality in near future.

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This paper describes the fundamental study about the evaporation and combustion characteristics of heavy fuel oil. Firstly, the difference of thermogravimetric curves between heavy fuel oil and marine diesel oil was examined using a thermobalance. Secondly, the combustion characteristics of a single droplet of both fuels were observed in detail using a high-speed video camera. Furhermore, the four types of hydrocarbons, saturated hydrocarbons“Sa”, aromatic hydrocarbons“Ar”, resin“Re”and asphaltene“Asp”were extracted from the fuels and evaporation and single droplet combustion characteristics of each were examined. The results obtained from the examinations are as follows: (1) Ar are surely one origin of soot formation. In case of marine diesel oil combustion, it is possible that combustion of Sa improves the combustion of Ar. Howevver, for heavy fuel oil which includes much heavier components, further investigation in combustion characteristics of Ar, Re and Asp is necessary.; (2) Asp is the heaviest component to evaporate and easy to form cinder after the single droplet combustion. Further, in one experiment all Asp was extracted from heavy fuel oil. This fuel then showed better evaporation and combustion characteristics (i.e. less cinder formation) than normal heavy fuel oil.

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It is important to know the characteristics (kinematic viscosity, water, Total Base Number, insolubles in pentane) of the system oil for the marine diesel engine operation. However, the conventional analysis for the system oil depending on the standard (such as ASTM, JIS, IP, etc) takes plenty of time, labor and cost. It doesn't always follow that the conventional analysis is the best. In order to keep a good engine operation and trouble-free, more quick analysis is required.
This paper examines the correlation between the characteristics of the 4-cycle marine diesel engine system oil in use and its infrared spectra. As the result, it is realized that we can quickly estimate the characteristics of the system oil by infrared spectra. We visualize the necessary care to be taken and problems encountered on estimating the characteristics.
And, this paper shows the feature of infrared spectra of the system oil during engine trouble (Blow-by) . We consider it from the view point of the diameter of soot particle.
Furthermore, we apply this method to the 2-cycle marine diesel engine system oil which has the increase of TBN and kinematic viscosity. These results suggest a lot of important information for engine operation, and this method is effective for estimating conditions of the system oil in a 2-cycle engine as well as a 4-cycle engine.

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