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Discuss Challenges with traditional fuel purification systems on existing ships with the latest emission control requirements, storage & purification of marine fuel oils on board has become a challenge for CE’s. Against this background,

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  • Discuss Challenges with traditional fuel purification systems on existing ships with the latest emission control requirements, storage & purification of marine fuel oils on board has become a challenge for CE’s. Against this background,

    Discuss Challenges with traditional fuel purification systems on existing ships with the latest emission control requirements, storage & purification of marine fuel oils on board has become a challenge for CE’s. Against this background,
    Last edited by mohit; 12-21-2017, 10:37 AM.

  • #2
    Centrifugal separators are used to separate sludge, water, cat fines, etc. The efficiency of a centrifugal separator is affected by

    i. The composition of the fuel

    ii. The quantity of fuel

    iii. The temperature of fuel

    iv. Cleanliness of the separator and its general working conditions

    - Maximum Aluminium and Silicon (Al+Si) limit: In a complex refinery, HFO is used as a blending component. Mechanically damaged aluminium silicate catalyst particles

    of

    the catalytic cracker are not entirely removed from the HFO stream, and are found in mg/kg amounts in heavy fuel blended with HFO.


    In order to avoid abrasive damage in the fuel system onboard the vessel, it is necessary to limit the amount of Al+Si to a level which can be adequately removed by the

    ship’s fuel cleaning system


    - Maximum total sediment aged limit: The visbreaking process deteriorates the stability of asphaltenes, and instability problems can cause fuel purification and filter-

    blocking difficulties, hence the need for a specification to ensure adequate fuel stability


    For fuel oils with a viscosity above 180 mm2/s at 50°C, it is recommended that the highest possible temperature (98°C) be maintained. The fuel oil has to remain in the

    centrifuge bowl for as long as possible by adjusting the flow rates through the centrifuge so that it corresponds to the amount of fuel required by the engine.


    - To ensure optimal cleaning of a fuel oil, a second separator can be used in the series operation, for example, a purifier followed by a clarifier. The density limit of 991

    kg/m3 is not applicable to clarifier operation, but the combined system of purifier and clarifier in series remains restricted to a maximum density of 991 kg/m3 at 15°C.


    Heavy movements of the vessel can stir up dirt, water and sludge that have accumulated over time on the bottom of the bunker and settling tanks. Efficient purification

    is

    not always possible when separators have been put in a parallel purifying function.


    - In a conventional clarifier, the water outlet is closed off, and the separated water can only be discharged with the sludge through the sludge ports at the bowl

    periphery. A

    sludge discharge causes turbulence in the bowl and leads to less efficient separation.


    Consequently, the water handling capability of a conventional clarifier is insufficient for the cleaning of fuel oil if the fuel oil has a significant amount of water. (The prior

    use

    of a purifier with its continuous water removal is mandatory
    Last edited by deepak; 12-20-2017, 12:57 PM.

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