Environmental Engineering Reference
In-Depth Information
Table 15.6 Marine engine's specific fuel consumption (SFC)
Energy supply
Engine work kW
(BTU
s
-1
)
SFC
B5,000
(B4,739)
5,000-15, 000
(4,739-14,218)
C15,000
(C14,218)
g kWh
-1
(oz BTU
-1
)
195-185
((20-19) 9 10
-4
)
185-175
((19-18) 9 10
-4
)
175-150
((18-16) 9 10
-4
)
Table 15.7 Auxiliary engine fuel consumption
Energy supply
Auxiliary engine work kW
(BTU s
-1
)
SFC
C800
(C758)
\800
(\758)
g kWh
-1
(oz BTU
-1
)
200-210
((21-22) 9 10
-4
)
210-220
((22-23) 9 10
-4
)
• SFC values are given also with ±5% tolerance because of engine wear, ageing
and sub-optimal maintenance of fuel injectors and injection pumps, deterioration
of the propeller, defects in the turbocharger, increased filter resistances and wear
and tear of the heat exchanger.
The SFC of the main engine depends on the performance of the engine; see
Table
15.6
[
38
].
The fuel consumption depends on a number of parameters including average
load, number of speed variations, chosen route, wind and rain, waves, degradation
of the hull and drag of the ship.
15.5.2 Average Auxiliary Engines
All ships use residual fuel and need it to power different engines and equipment
on-board. When the ship is at sea, the heat is taken from the exhaust gas through
the steam boilers and hence no additional fuel is consumed. In port, the main
engine does not run and the ships need auxiliary engines and boilers using extra
fuel to generate heat.
The SFC of auxiliary engines primarily depends on the power they need; see
Table
15.7
[
39
].
The average calculation of a ship's economy includes the auxiliary engine's
fuel consumption although the load and operating hours of auxiliary engines
greatly varies between types of ships. This is especially true in tankers, where heat
is required for cargo heating, pumping, and the energy supply of auxiliary
equipment. Fuel consumption of auxiliary equipment in tankers can be 20-25% of
the whole consumption.
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