12.4 Gas fuels
When the engine operates in gas mode, the primary fuel is natural gas. The gas fuel is injected
at low pressure. The ECS controls electronically the injection timing and the gas fuel quantity.
Usually, the gas fuel is stored as Liquefied Natural Gas (LNG). There are different designs of
the external gas supply system and the LNG storage. The gas supply system supplies natural
gas at the correct temperature and pressure to the engine. For more data, refer to the
documentation of the related manufacturer.
The gas fuel has to obey the WinGD specifications, refer to Table 12-1 - Specifications for gas
fuel.
Tab 12-1 Specifications for gas fuel
Parameter
Value
1
Lower heating value (LHV)
≥ 28 MJ/Nm
3
Methane content ≥ 70% volume
Hydrogen sulphide (H
2
S) ≤ 0.05% volume
Hydrogen (H
2
) ≤ 3% volume
Ammonia
≤ 25 mg/Nm
3
Chlorine and fluorine
≤ 50 mg/Nm
3
Dew point of water ≤ -20°C
Oil (aerosol liquid and vapour)
≤ 1 mg/Nm
3
Gas cleanliness
Gas is thought as sufficiently clean
2
Gas temperature at engine inlet, if ambient tem-
perature is ≥ 20°C
20°C to 60°C
Gas temperature at engine inlet, if ambient tem-
perature is < 20°C
≥ ambient temperature, but always ≥ 0°C
3
1
Values given in Nm
3
are at 0°C and 101.3 kPa.
2
Prevent contamination from the gas system. For this, flush the gas pipes correctly, make
sure of the cleanliness of the bunkering connections etc.
3
The cause of this value is to prevent condensation in the annular spaces of the gas
pipes. If necessary, you can do one of the two procedures that follow:
•
Increase the temperature of the gas to more than the dew point temperature of
the ambient air.
•
Decrease the water content of the ambient air.
X92DF
AA00-0000-00AAA-030J-A
Operation Manual Gas fuels
Winterthur Gas & Diesel Ltd.
- 602 - Issue 002 2020-08
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