The vessel bunkered RMG 380 grade fuel at Vlissingen – Netherlands. The regular full spec analysis indicated the density to be off-spec which was marginally higher than 991 Kg/m3.
The newly bunkered fuel was put in use upon exhausting the old bunkers. The transfer pump suction filters started to get clogged at first, after which the purifier feed pump suction filters. The filters were getting clogged every 20 minutes.
After couple of hours, purifiers started to get clogged and the engineers observed heavy sludge formation, which completely clogged the sludge discharge pipe.
Now, a question for all who has sailed on board ships!
Given this scenario, don’t you think it is an unsafe situation with a potential for the vessel to suffer propulsion failure or loss of power?
If the fuel supplied is of a good quality, how can a fuel cause such heavy sludge generation and frequent clogging of filters?
I will leave it to you to think beyond!
Image 1: Clogged Sludge Discharge Pipe
Image 2: Heavy Sludge Generation In the Purifiers
Image 3: Could a Good Fuel Cause such Sludge Formation?
The ship Management approached Viswa Lab to find out the root cause of the problems being faced on board. Certain additional tests were done on the fuel and below where the abnormalities found.
A GCMS test was done on the fuel sample, which revealed significant chemical contamination as quantified in the below table:
Image 5: Both Purifiers Severely Clogged
Image 6: How Can This be a good fuel – though with in ISO 8217 specifications?
These chemicals are usually not present in the marine fuels and Viswa Lab has witnessed that when these chemical contaminants are present more than 100 ppm, problems are likely to occur.
After identifying the root cause, Viswa Lab suggested actions to mitigate and safely use the fuel.
Special Information for your Understanding:
- Phenols may come from low cost shale oil used as cutter stock. Phenols produce instability, add to the acidity of the fuel and have a negative effect on the ignition and combustion properties.
- Pyrolysis gasoline is a benzene rich byproduct of the ethylene manufacturing plants.
- Traditionally pyrolysis gasoline is blended with motor gasoline because of its high octane number. Only small portions are blended owing to unacceptable odour and its gum forming tendencies. When this pyrolysis gasoline is dimerised and distilled, first the lighter hydrocarbons, then Benzene, Toulene, o-Xylene and Styrene, then DCPD and finally heavier hydrocarbons (like Indene) are separated. Styrene and DCPD have gum forming tendencies at high temperatures. Usually, presence of Styrene and DCPD indicates possible presence of other gum forming compounds in any form (monomers, dimers, trimers, tetramers etc). CPD is a monomer and DCPD is a dimer.
Source: Viswa Lab
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