Exam Question
Give an outline sketch of Heavy F.O. settling tank heating system and briefly explain the system. Sketch only the low pressure steam inlet upto condensate collection tank. (16)
Class 4 (4th Engineer)
MEKG
📅 Jul 2025
Reference Answer
### 1. Purpose of HFO Settling Tank Heating
The primary purpose of heating Heavy Fuel Oil (HFO) in a settling tank is to reduce its viscosity. This is crucial for two main reasons:
* **Pumpability**: HFO at ambient temperatures is often too viscous to be pumped effectively. Heating brings it to a suitable viscosity (typically around 15-20 cSt) for transfer by the fuel oil transfer pumps to the service tank and subsequently to the purifiers.
* **Separation (Settling)**: Heating the oil reduces its density and promotes the separation of entrained water and solid particles (sludge) through gravity. The water and sludge, being denser, settle at the bottom of the tank from where they can be drained off.
The primary purpose of heating Heavy Fuel Oil (HFO) in a settling tank is to reduce its viscosity. This is crucial for two main reasons:
* **Pumpability**: HFO at ambient temperatures is often too viscous to be pumped effectively. Heating brings it to a suitable viscosity (typically around 15-20 cSt) for transfer by the fuel oil transfer pumps to the service tank and subsequently to the purifiers.
* **Separation (Settling)**: Heating the oil reduces its density and promotes the separation of entrained water and solid particles (sludge) through gravity. The water and sludge, being denser, settle at the bottom of the tank from where they can be drained off.
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