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The
continuously increasing fuel costs of these recent years made fuel
management not just a normal cost item in the yearly company budget but one of the most strategical issues to be planned beforehand in order
to be competitive on the market.
Shipping
world is a typical
example. Medium sized merchant ships (e.g. a 150000 tonn tanker or bulk
carrier, a 3500TEU container carrier, or a 2500m lanes Ro-Ro/pax ferry) are
normally powered with engines which are rated 10-15MW. Not to speak about
cruise vessels which have a much larger installed power.
Typical
specific fuel consumption is about 180gr/kWh for low speed two stroke
diesels and for four stroke medium speed ones, and about 220gr/kWh for
gas turbines.
It must be noted that specific fuel consumption varies according to engine speed
and torque
and is also influenced by external factors such as actual fuel composition,
cleanliness of engine fuel system and of fuel treatment modules, engine
room temperature, atmospheric pressure, humidity and sea state.
With
LTM2214 the engine speed at which specific fuel consumption is minimum can
be determined continuously and an alarm can be set if the desired
threshold is exceeded.
Examples of fuel costs reduction achievable with LTM2214 system usage
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Using the LTM2214 system
interfaced to a fuel meter (not supplied by Advanced Measurement Solutions)
it is possible to optimize specific fuel consumption and to run the engine
at its optimal performance.
-
If
warning and alarm thresholds are set properly it is possible to alert the
operator that the working parameters of the engine drifted and that
specific fuel consumption is increased.
Introductory note:
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Specific fuel consumption values used in the following
examples are the ones given by the most important manufacturers obtained
during test bed measurements and are the best figures theoretically
obtainable. Usually the bigger the size of the engine, the lower
the specific fuel consumption and viceversa.
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But in real working conditions specific fuel consumption can
be much higher due to the fact that the actual engine working parameters are different
from testbed ones. In fact temperature,
pressure, humidity, RPM, load, sea state, propeller and shaftline hull
induced effects influence specific fuel consumption greatly.
-
In the following examples a specific fuel consumption close
to testbed figures was selected as this is the worst case (money saving is minimum).
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Moreover fuel prices used in the examples (january-march 2009)
are the minimum of the last years (e.g.
in august 2008, and during years 2011-2012, fuel prices were more than two times these figures).
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Consequently the calculated saving figures (in USD) are
underestimated.
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For up to date fuel
quotations
click here.
In the following examples a specific fuel consumption
improvement of 1.5% was assumed.
In normal conditions, using the LTM2214 system properly, the
achievable saving can be much higher!
A) Two stroke slow speed / four
stroke medium speed diesel engines
The specific fuel consumption of these two engine typologies
are within the following ranges:
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1)
160-180g/kWh
for two stroke slow speed diesels
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2)
175-190g/kWh
for four stroke medium speed diesels
Typical implemetations of this category range from small
merchant vessels (two stroke slow speed from 5MW to 15MW), to large
container ships of 10000TEU (two stroke slow speed from 50MW to 80MW), to Ro-Ro
ferries for which, due to the limited engine room height, four stroke
medium speed engines are used from
20MW to 50MW fractioned on several units (typically two for each shaft).
To simplify the calculation an intermediate value of the
specific fuel consumption was assumed valid for both two stroke slow speed and
four stroke medium speed ones.
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Typical specific fuel consumption: 0.180kg/kWh
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Intermediate fuel oil price (IFO 380 jan-mar
2009): 0.250 USD/kg (year min) (year max: 0.76USD/kg)
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Marine diesel oil price (MDO jan-mar 2009):
0.400 USD/kg (year min) (year max: 1.32USD/kg)
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Estimated specific fuel consumption improvement using the LTM2214
system: 0.0027kg/kWh (1.5% improvement)
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Achieved specific fuel consumption: 0.1773kg/kWh
-
-
Engine power: 10MW
|
|
Fuel consumption at
0,180kg/kWh |
Fuel consumption at 0,1773kg/kWh |
Fuel consumption
reduction |
Cost reduction with
IFO380 |
Cost reduction with MDO |
|
|
(tonn) |
(tonn) |
(tonn) |
(USD) |
(USD) |
|
1
month |
1296,0 |
1276,6 |
19,4 |
4860 |
7776 |
|
6
months |
7884,0 |
7765,7 |
118,3 |
29565 |
47304 |
|
1
year |
15768,0 |
15531,5 |
236,5 |
59130 |
94608 |
Engine power: 25MW
|
|
Fuel consumption at 0,180kg/kWh |
Fuel consumption at 0,1773kg/kWh |
Fuel consumption
reduction |
Cost reduction with
IFO380 |
Cost reduction with MDO |
|
|
(tonn) |
(tonn) |
(tonn) |
(USD) |
(USD) |
|
1
month |
3240,0 |
3191,4 |
48,6 |
12150 |
19440 |
|
6
months |
19710,0 |
19414,4 |
295,7 |
73913 |
118260 |
|
1
year |
39420,0 |
38828,7 |
591,3 |
147825 |
236520 |
Engine power: 50MW
|
|
Fuel consumption at 0,180kg/kWh |
Fuel consumption at 0,1773kg/kWh |
Fuel consumption
reduction |
Cost reduction with
IFO380 |
Cost reduction with MDO |
|
|
(tonn) |
(tonn) |
(tonn) |
(USD) |
(USD) |
|
1
month |
6480,0 |
6382,8 |
97,2 |
24300 |
38880 |
|
6
months |
39420,0 |
38828,7 |
591,3 |
147825 |
236520 |
|
1
year |
78840,0 |
77657,4 |
1182,6 |
295650 |
473040 |
Engine power: 75MW
|
|
Fuel consumption at 0,180kg/kWh |
Fuel consumption at 0,1773kg/kWh |
Fuel consumption
reduction |
Cost reduction with
IFO380 |
Cost reduction with MDO |
|
|
(tonn) |
(tonn) |
(tonn) |
(USD) |
(USD) |
|
1
month |
9720,0 |
9574,2 |
145,8 |
36450 |
58320 |
|
6
months |
59130,0 |
58243,1 |
887,0 |
221738 |
354780 |
|
1
year |
118260,0 |
116486,1 |
1773,9 |
443475 |
709560 |
B) Aeroderivative gas turbine (GT)
The specific fuel consumption of this typology of engines ranges
from 210g/kWh to 230g/kWh.
Typical implementations of this category range from naval
ships (from 20MW to 100MW), to cruise ships (from 15MW to
50MW), to special vessels (record breakers or megayachts) for which the GT
is used essentially for its low weight/power ratio (from 5MW to 100MW). To
simplify the calculation an intermediate value of the specific fuel
consumption was assumed. The MDO cost reduction is calculated only to
allow the comparison with the MGO.
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Typical specific fuel consumption: 0.220kg/kWh
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Intermediate fuel oil price (MDO jan-mar 2009):
0.400 USD/kg (year min) (year max: 1.32USD/kg)
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Marine diesel oil price (MGO al jan-mar 2009):
0.460 USD/kg (year min)
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Estimated specific fuel consumption improvement using the LTM2214
system: 0.0033kg/kWh (1.5% improvement)
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Achieved specific fuel consumption: 0.2167kg/kWh
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-
Engine power: 10MW
|
|
Fuel consumption at 0,220kg/kWh |
Fuel consumption at 0,2167kg/kWh |
Fuel consumption
reduction |
Cost reduction with MDO |
Cost reduction with MGO |
|
|
(tonn) |
(tonn) |
(tonn) |
(USD) |
(USD) |
|
1
month |
1584,0 |
1560,2 |
23,8 |
9504 |
10930 |
|
6
months |
9636,0 |
9491,5 |
144,5 |
57816 |
66488 |
|
1
year |
19272,0 |
18982,9 |
289,1 |
115632 |
132977 |
Engine
power: 25MW
|
|
Fuel consumption at 0,220kg/kWh |
Fuel consumption at
0,2167kg/kWh |
Fuel consumption
reduction |
Cost reduction with MDO |
Cost reduction with MGO |
|
|
(tonn) |
(tonn) |
(tonn) |
(USD) |
(USD) |
|
1
month |
3960,0 |
3900,6 |
59,4 |
23760 |
27324 |
|
6
months |
24090,0 |
23728,7 |
361,3 |
144540 |
166221 |
|
1
year |
48180,0 |
47457,3 |
722,7 |
289080 |
332442 |
Engine
power: 50MW
|
|
Fuel consumption at 0,220kg/kWh |
Fuel consumption at 0,2167kg/kWh |
Fuel consumption
reduction |
Cost reduction with MDO |
Cost reduction with MGO |
|
|
(tonn) |
(tonn) |
(tonn) |
(USD) |
(USD) |
|
1
month |
7920,0 |
7801,2 |
118,8 |
47520 |
54648 |
|
6
months |
48180,0 |
47457,3 |
722,7 |
289080 |
332442 |
|
1
year |
96360,0 |
94914,6 |
1445,4 |
578160 |
664884 |
Engine
power: 75MW
|
|
Fuel consumption at 0,220kg/kWh |
Fuel consumption at 0,2167kg/kWh |
Fuel consumption
reduction |
Cost reduction with MDO |
Cost reduction with MGO |
|
|
(tonn) |
(tonn) |
(tonn) |
(USD) |
(USD) |
|
1
month |
11880,0 |
11701,8 |
178,2 |
71280 |
81972 |
|
6
months |
72270,0 |
71186,0 |
1084,0 |
433620 |
498663 |
|
1
year |
144540,0 |
142371,9 |
2168,1 |
867240 |
997326 |
C) Diesel electric propulsion
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Diesel electric propulsion is based on an electric power
plant fractioned on several medium speed diesel generators (usually from
four to six units) in order to be able to distribute the load between
the generators and to make each generator work at the lowest specific
fuel consumption value. The generated voltage is fed to the
propulsion static converters which generate a voltage variable in
frequency and amplitude which is then fed to the electric propulsion motors.
The propulsion converters allow the control of the RPM and of the torque
applied to the propeller.
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The specific fuel
consumption value of this configuration is similar to the one of medium
speed diesel direct propulsion
which ranges from 175g/kWh to 190g/kWh. The mechanic-electric-mechanic
energy conversion worsen the overall theoretical propulsion system
efficiency adding a 6% loss (propulsion transformers, cyclo/synchro/PWM
conveters, propulsion electric motors (PEM) windings and excitation give
their contribution to losses). But diesel generators fractioned power permits
to obtain a good specific fuel consumption value for each sailing
configuration (e.g. during manoeuvring only 2 diesel generators loaded at
85% MCR are used, while sailing at the maximum speed 4 or 5 diesel generators
still loaded at 85% MCR are used. In this way a more flexible system is
obtained if compared to engine-propeller direct coupling, and the above
mentioned 6% efficiency loss is easily recovered.
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The overall system efficiency can be further improved
installing an LTM2214 system on each shaftline in order to obtain a more
accurate reading of the power delivered to each shaft. In fact the power
value given by static propulsion converters usually is not very
accurate.
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Moreover if a signal corresponding to the the electrical
power absorbed by each PEM propulsion system is sent to the LTM2214 fuel
consumption input, the efficiency of the electric propulsion system can
be displayed (typical values range from 0.92 to 0.95).
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