WinGD X72DF, Руководство по установке

Страница: 111 / 237

Marine Installation Manual 2021-08 4-36
4 Ancillary Systems
4.4 Fuel gas system
X72DF
4.4.3 Gas specifications
As a dual-fuel engine, the X-DF engine is designed for continuous service in gas
or in diesel operating mode. For continuous operation without reduction in rated
output, the gas which is used as the main fuel in gas operating mode must fulfil
the quality requirements provided in
Table 4 - 7 . The gas properties are defined at
the engine inlet (for the iGPR, see section 4.4.6,

4-52 ) and the inlet of the gas
valve unit (for the GVU, see section 4.4.7,  4-54 ).
Table 4 - 7 Gas specifications
Property
Value
(values given in Nm
3
are at 0°C and 101.3kPa)
Lower Heating Value (LHV) ≥ 28MJ/Nm
3
Minimum methane number 65 for 100% engine power
60 for 85% engine power
Influence of methane number on the
maximum engine output
See Figure 4 - 18,

4-37 .
Methane content ≥ 70% volume
Hydrogen sulphide (H
2
S) ≤ 0.05% volume
Hydrogen (H
2
)
a)
a) Hydrogen content higher than 3% volume must be considered on a project-specific basis.
≤ 3% volume
Ammonia ≤ 25mg/Nm
3
Chlorine and fluorine ≤ 50mg/Nm
3
Dew point of water ≤ -20°C
Oil (aerosol liquid and vapour) ≤ 1mg/Nm
3
Gas cleanliness Gas is considered as sufficiently clean.
b)
b) Contamination from the fuel gas supply system must be avoided, e.g. by correct pipe flushing, en -
suring cleanliness of bunkering connections, etc.
Gas temperature at relative inlet
c)
c) The gas properties are defined at the engine inlet (for iGPR, see section 4.4.6,

4-52 ) and the inlet
of the gas valve unit (for GVU, see section 4.4.7,

4-54 )
0-60°C. Note that no condensate is allowed in the
annular space of the main engine gas piping.
d)
d) If the gas temperature falls below the ambient air temperature (or the ambient air dew point, if de -
termined), a dedicated dry air supply must be used from one of the following methods:
— from control air supply (ISO 8573-1, class x-4-x to be fulfilled, i.e. dew point ≤ 3°C)
— from air dryer (ISO 8573-1, class x-4-x to be fulfilled, i.e. dew point ≤ 3°C)
— from working air supply (as long as gas temperature is > 20°C)
Gas feed pressure
e)
e) The required gas feed pressure depends on the LHV as well as on the specific engine rating and ac -
tual engine load (specified in GTD ). Details regarding feed pressure layout can be found in section
4.4.5,

4-47 .
According to GTD
Permissible gas pressure fluctuation ± 0.6bar (across all frequencies)