Tuesday, May 1, 2018

Calculation of F.O Settling Tank


What is the purpose of the settling tank?
This is a deep tank in the engine room used for pre-cleaning of fuel oils by gravity; a liquid mixture in the settling tank clears slowly as a heavier liquid and solids sink to the bottom under influence of gravity.

In the Fuel oil transfer system, FO settling tank received fuel oil from Fuel oil storage tank via Fuel oil Transfer pump. After this, the stage then we called Fuel oil treatment system.
From the settling tanks fuel oil is transferred to the service tanks via FO treatment system. For cleaning of heavy fuel oils (HFO) the two stage process is commonly used. The fuel is heated in a settling tank to about 50-60°C and then is drawn out by the purifier inlet pump.

F.O Settling tank Requirement
Two settling tanks should be installed, in order to obtain thorough pre-cleaning and to allow fuels of different origin to be kept separate. When using RMfuels, recommend two settling tanks for each fuel type (high sulphur HFO, low sulphur HFO).

Pre-cleaning by settling is the more effective the longer the solid material is given time to settle. The storage capacity of the settling tank should be designed to hold at least a 24-hour supply of fuel at full load operation, including sediments and water the fuel contains.

Tanks should be designed to provide the most efficient sludge and water separation. Each settling tank should be provided with baffles to reduce mixing of sludge with the fuel. The bottom of the tank should be with slope toward the sludge drains, and pump suction shall be not in the vicinity of the sludge space. The temerature in fuel settling tanks should be as high as possible to help the dirt to settle. However, the temperature should be below 75°C in order to avoid the formation of asphaltenes, and min 7°C above the pour point of the fuel to ensure pumpability.

The minimum volume (V) to be provided is:

Where :

V [m3] = Minimum volume
P [kW] = Engine Power rating


Hopefully helpfully 😊
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