Stationary bunker fuel blending for seagoing vessels

Blending heavy fuel oil (HFO), also known as marine fuel oil (MFO), with diesel fuel to make intermediate fuel oil (IFO) in stationary bunker stations

Process

Today's seagoing vessels often use IFO as fuel. IFO is a blend of cheap heavy fuel oil (HFO) and expensive diesel oil. The fuel is classified using the grades IFO 180, 380 or 580 with higher numbers signifying higher viscosities. At 15°C, IFO has a consistency similar to that of bitumen and is barely pumpable so it must be heated to approx. 50 to 60°C.

The required viscosity is determined by the technical conditions on the ship (storage and preheating temperature, injection nozzle viscosity, and maximum pump viscosity). IFO 380 has a viscosity of 380 cSt @ 50°C.

The diesel oil is admixed directly in the heavy oil pipeline where there is a static mixer. This pipeline leads to the bunker bridge or directly to the ship.

According to MARPOL regulations, a representative sample of each fuel delivery must be taken throughout the bunkering process. The ViscoScope® viscometer measures the viscosity of the bunker fuel continuously during bunkering to ensure the correct amount of diesel oil is added. Furthermore, it documents changes in viscosity throughout the process to a level far in excess of the requirements of MARPOL regulations. The ViscoScope® viscometer measures the dynamic viscosity x density. The operator can enter a fixed density value on the ViscoScope® transmitter or connect a densitometer to display the kinematic viscosity.

The nominal diameter of the bunker oil pipes leading to the bridge or ship is 8”. A 3” socket is welded into a 90° pipe bend to retain the ViscoScope® sensor which is aligned axially to the flow direction. Alternatively, it can be installed in the manifold to the bunker bridge – enabling several bunker stations to be regulated using one ViscoScope® viscometer. In both cases, the ViscoScope® sensors are equipped with a non-active extension (NAE) which positions the probe in thecenter of the flow.

Benefits for Marimex Costumers

• Continuous monitoring and regulation of diesel oil addition
• Complete documentation of the bunkering process, far in excess of the requirements of MARPOL regulations.