Håkon B. Thoresen 24 September 2009 Fuel changeover considerations HFO-MGO INTERTANKO Bunker...

Håkon B. Thoresen 24 September 2009

Fuel changeover considerations HFO-MGO

INTERTANKO Bunker Sub-committee, Nafplia, Greece

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24 September 2009

2

Fuel Change-over challenges (HFO MGO)?

Fuel Pumps

Thermal damages due to inadequate engine cool-down.

Damages due to insufficient lubricity of the fuel

Damages due to gasing of MGO

Fuel Preheaters

MGO should by-pass the fuel preheaters during operation

Fuel Tank

Fuel in the return/recirculation pipes returned to correct fuel tank?

MGO tank capacity/availability?



24 September 2009

3

Fuel Change-over challenges (HFO MGO)?

Burners (Boilers)

Fuel pumps should be changed or modified to accommodate the lower viscosity fuel.

Post-purge of the furnace after MGO use is recommended.

Pressure jet burner

A lower viscosity may cause an increase in the fuel input through the nozzle (increase risk of smoke emission)

Rotary cup burner

The fuel amount (pressure) should be checked/adjusted in order to obtain a reasonably smokefree combustion

Gassing of MGO if a suitable heat shield is not fitted

Steam atomising burner

MGO may cause overfiring if the pressure alone controls the oil amount of the burner.



24 September 2009

4

Change-over from HFO to MGO/MDOWhen switching from residual to distillate fuel, changing the fuel temperature

too quickly or uneven temerature changes may cause thermal shock causing uncontrolled clearance adaptation which can result in sticking/scuffing of the fuel valves, fuel pump plungers, and suction valves.

The temperature increase/decrease rate should be less than 2°C/min* to protect the fuel equipment from thermal shock

Courtesy Man B&W

*Wartsila allow up to 15°C/min temperature increase/decrease according to service letter RT-82



24 September 2009

5

Change-over from HFO to MGO/MDO There is a possible risk of incompatibility when the

two fuels are mixed together. In particular, the addition of a paraffinic-type distillate fuel to a thermally cracked heavy fuel often correlates with poor solubility of asphaltenes

The mixed fuel could result in some of the asphaltenes coming out of solution and forming sludge. This may cause clogging of filters and separators, sticking of fuel injection pumps (deposits on plunger and barrel), and plugged fuel nozzels.

The mixture is not expected to be homogeneous immediately and some temperature/viscosity fluctuations are to be expected. The process therefore needs careful monitoring of temperature and viscosity.



24 September 2009

6

Change-over from HFO to MGO/MDO

Man Diesel recommend that the compatibility of the two fuels is checked – preferably at the bunkering stage.

ASTM D 4740 - This test method covers the determination of the compatibility between a residual fuel and a blend stock (MDO or MGO).

This procedure is used to identify fuels that, if mixed, could result in excessive centrifuge loading, strainer plugging, tank sludge formation, or similar operating problems.

Compatible Incompatible



24 September 2009

7

Change-over from HFO to MGO/MDO

0%

20%

40%

60%

80%

100%B

razi

l

Japa

n

Kor

ea

Gib

ralta

r

Pan

ama

US

A

UK

Chi

na

Spa

in

Rus

sia

Ger

man

y

Italy

The

Net

herla

nds

Bel

gium

Den

mar

k

Sin

gapo

re

Gre

ece

Sou

th A

fric

a

Comp. 5

Comp. 4

Comp. 3

Comp. 2

Comp. 1

NOT compatible

Compatible

Mixing HFO with MGO/MDO from the same port



24 September 2009

8

MGO Quality Lubricity may be poor in ultra low sulphur fuels (<0.05%)

The use of MGO/MDO with a sulphur content close to zero and, at the same time, a low viscosity might cause fuel pump and fuel valve wear and, consequently, the risk of sticking.

During service on low viscosity fuel, internal leakages in the fuel equipment will increase and there might be a risk of starting difficulties

ISO 8217 DMA (MGO) spec has a minimum viscosity @ 40°C of 1.40 mm2/s

MAN Diesel limits the viscosity at the engine inlet to min. 2 cSt.



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MGO/MDO 2009 – Sulphur ≤0.10

Visc 3.0-3.536%

Visc 3.5-4.012%

Visc ≥4.011%Visc 2.0-2.5

8%

Visc 2.5-3.033%

***Viscosity at 40˚C (mm²/s)***

***Percentage of MGO/MDO samples tested: Jan – June 2009***



24 September 2009

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MGO/MDO 2009 – Sulphur ≤0.05

Visc 3.0-3.530%

Visc 3.5-4.011%

Visc ≥4.08%

Visc 2.0-2.515%

Visc 2.5-3.036%

***Viscosity at 40˚C (mm²/s)***

***Percentage of MGO/MDO samples tested: Jan – June 2009***



24 September 2009

11

MGO/MDO 2009 – Sulphur ≤0.10 and Flash Point

6.4 5.7

50.5

34.8

22.5

8.3

37.8

34.7

29.3

22.5

12.3

5.3

24.8

46.3

69.283.2

0.40.01.94.1

0%

20%

40%

60%

80%

100%

2.0-2.5 2.5-3.0 3.0-3.5 3.5-4.0 ≥4.0Viscosity at 40°C (mm2/s)

<60°C FP 60-65°C FP 65-70°C FP ≥70°C FP



24 September 2009

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Safeguarding life, property and the environment

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