Catalytic Fines (Catfines – Al & Si)
Catalytic fines (also known as catfines) are aluminium and silicon oxides used during refinery catalytic cracking. Catfines are extremely hard and abrasive particles which can cause excessive wear to vital components in the combustion chamber such as the piston grooves, piston rings, cylinder liners and fuel injection equipment.
It is stated in ISO 8217:2005 Table 2, with regards to fuel specifications, that the maximum amount of catfines allowed per kilogram of fuel should be limited to 80 milligrams. The sample used to test for catfines concentration should be collected at the point of custody transfer during bunkering. The catfines limit for RME 180 fuels was reduced to 50 ppm in ISO 8217:2010, ISO 8217:2012 and ISO 8217:2017. The catfines limit for RMG and RMK fuel grades, on the other hand, has been reduced to 60 ppm.
Vessels ideally should have fuel treatment system installation on board (Tank Design/Centrifuges/Filters) operating at optimum efficiency to counteract fuel quality that is supplied closer to the upper limits of ISO standards, reducing the catfines concentration of the received fuel.
There have been cases where overwhelming levels of catfines have been allowed to accumulate in fuel oil tanks which have a very real possibility of mixing back into the fuel service system. It only requires a sudden increase in catfines content within a small time frame to cause extensive damages to vessels engines leading to breakdowns.
Engine builders recommend that after the onboard treatment, fuels entering the engine should have a catfines concentration of less than 10-15 ppm..
Fuel System Check
Operators should be more concerned with the level of catfines in the fuel entering the engine than the level of catfines in the fuel from the bunkering sample, as accumulated catfines in the fuel oil system is usually unknown without testing.
When the vessel receives fuels with a catfines concentration of more than 30 ppm, a Fuel System Efficiency Check should be carried out to ensure that the separation efficiency is up to standard. This will help the engineers in ascertaining that the fuel treatment systems onboard are capable of reducing the catfines content to a safe level
Catalytic fines are hydrophilic. Therefore, regular draining of the service and settling tanks will reduce the volume of catfines, which are drained with the water.
Using 10-micron final hot filters instead of 50micron filters will also help to reduce the amount of catfines reaching the engine.
The vessel crew should check the fuel separation and treatment systems by periodically sending onboard samples, which are to be obtained from the following locations, for testing.
Limiting the catfines concentration entering the engine will increase mean time between overhauls and improve the service life of engine components
Maritec Pte Ltd, A member of CTI Group, was incorporated in 1999 as a marine fuel laboratory providing analysis results and technical advice to a portfolio of international shipping companies.
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