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<p><b><font face="Arial" size="5">MPT Consultancy, Marine Gas Turbine Application
Consultant</font></b></p>
<p><font face="Arial" size="4">More information on marine gas turbine types, configurations
and applications can be obtained from MPT Consultancy. Please contact:</font></p>
<p><font size="4" face="Arial">Alexander Harsema-Mensonides<br>
General Manager<br>
tel mobile +46 70 587 5796<br>
e-mail <a href="mailto:gasturbines@mptconsult.com"><font face="Arial" size="4">gasturbines@mptconsult.com</font></a></font></p>
<p><font face="Arial" size="4">MPT Consultancy<br>
Droskvägen 8<br>
S-246 57 Barsebäck<br>
Sweden</font></p>
<p><font face="Arial" size="4">tel +46 46 704 440<br>
fax +46 46 704 441<br>
e-mail <a href="mailto:info@mptconsult.com">info@mptconsult.com</a><br>
website <a href="http://www.mptconsult.com">http://www.mptconsult.com</a></font></p>
<p><b></b></p>
<p><b><font face="Arial" size="5">Marine Aero-derivative Gas Turbines</font></b></p>
<p><font face="Arial" size="4">What makes a gas turbine suitable or even ideal
for marine propulsion applications?</font></p>
<ul>
<li><font face="Arial" size="4">High output;</font></li>
<li><font face="Arial" size="4">Compact dimensions;</font></li>
<li><font face="Arial" size="4">Low weight;</font></li>
<li><font face="Arial" size="4">High torque;</font></li>
<li><font face="Arial" size="4">Low noise and vibrations;</font></li>
<li><font face="Arial" size="4">Low emission;</font></li>
<li><font face="Arial" size="4">Low lube oil consumption;</font></li>
<li><font face="Arial" size="4">Low maintenance;</font></li>
<li><font face="Arial" size="4">Rapid on-site engine module change-out;</font></li>
<li><font face="Arial" size="4">Rapid engine exchange.</font></li>
</ul>
<p><b><font face="Arial" size="5">Advantages of Marine Aero-derivative Gas Turbines</font></b></p>
<p><font face="Arial" size="4">Operation:</font></p>
<ul>
<li><font face="Arial" size="4">Gas turbines do not emit black smoke during
transient loads;</font></li>
<li><font face="Arial" size="4">Gas turbines pick up load very rapidly, at a
rate of about 1 MW per second;</font></li>
<li><font face="Arial" size="4">Turbines are "hands-off" machines,
if the control system does not indicate any problems, it does not need any
maintenance activity. During start-up, operation and shut-down, the gas turbine
is operated through the turbine control system, which controls fuel management,
but also monitors turbine condition. If any parameter exceeds pre-set limits,
the turbine control system will give and alarm and reduce turbine load to
avoid damage. In case of serious problems, the control system will shut down
the engine.</font></li>
</ul>
<p><font face="Arial" size="4">Maintenance:</font></p>
<ul>
<li><font face="Arial" size="4">Gas turbine control system monitors engine performance
and condition "on-line";</font></li>
<li><font face="Arial" size="4">"On-condition" maintenance avoids
unnecessary scheduled maintenance, replace what needs to be replaced;</font></li>
<li><font face="Arial" size="4">Modular gas turbine construction allows for
rapid exchange of engine modules, avoiding lengthy on-site repairs;</font></li>
<li><font face="Arial" size="4">Gas turbine size and weight allows for a complete
engine change-out on-site within hours, without dry-docking or extended stays
in port;</font></li>
<li><font face="Arial" size="4">Gas turbine and spares can be air freighted
worldwide.</font></li>
</ul>
<p><font face="Arial" size="4">Reliability and availability:</font><font face="Arial" size="4"><br>
</font></p>
<ul>
<li><font face="Arial" size="4">Aero-derivative gas turbines provide the very
high reliability (> 99.5%) and availability (97.5%) associated with aero
engines;</font></li>
</ul>
<p><font face="Arial" size="4">Environment:</font></p>
<ul>
<li><font face="Arial" size="4">Low NOx and SOx emissions;</font></li>
<li><font face="Arial" size="4">Low particulates emission;</font></li>
<li><font face="Arial" size="4">No visible smoke during transient loads;</font></li>
<li><font face="Arial" size="4">No fuel sludge from heavy fuel oils.</font></li>
</ul>
<p><font face="Arial" size="4">Noise and vibration:<br>
</font></p>
<ul>
<li><font face="Arial" size="4">Gas turbines are rotary machines, inherently
low structure borne noise;</font></li>
<li><font face="Arial" size="4">Gas turbines packages feature an acoustic enclosure,
reducing engine room noise levels and improving the quality of the working
environment in the engine room;</font></li>
<li><font face="Arial" size="4">Resilient package mounting reduces structure
borne noise even further;</font></li>
<li><font face="Arial" size="4">High pitched air borne noise is easily attenuated;</font></li>
<li><font face="Arial" size="4">Lower investment in air borne and structure
borne noise insulation.</font></li>
</ul>
<p><font face="Arial" size="4">Vessel design:<br>
</font></p>
<ul>
<li><font face="Arial" size="4">Low weight and compact dimension of gas turbine
and ancillary systems allows design freedom in terms of location of engine
room in the vessel;</font></li>
<li><font face="Arial" size="4">Smaller engine room leaves more space for revenue
making purposes;</font></li>
<li><font face="Arial" size="4">Low weight allows the engine room to be moved
away from the bottom of the vessel;</font></li>
<li><font face="Arial" size="4">Low noise and vibration levels improve crew
and passenger comfort, allowing engine room spaces to be located closer to
accommodation areas;</font></li>
</ul>
<p><font face="Arial" size="4">Propulsion plant design:<br>
</font></p>
<ul>
<li><font face="Arial" size="4">Gas turbines have exhaust gas mass flow and
temperature, which makes exhaust gas heat recovery both technically and economically
feasible.</font></li>
</ul>
<p><font face="Arial" size="4">Installation:<br>
</font></p>
<ul>
<li><font face="Arial" size="4">Gas turbine, control system and ancillaries
are packaged on skids, ready for installation in the building blocks in the
shipyard, speeding up the construction process;</font></li>
<li><font face="Arial" size="4">Gas turbine package with ancillaries are factory
tested, reducing commissioning time in the shipyard;</font></li>
<li><font face="Arial" size="4">Gas turbine packages and ancillaries are assembled
in the factory by specialized personnel, avoiding assembly problems and delays
in the shipyard;</font></li>
<li><font face="Arial" size="4">Gas turbines are air cooled, eliminating the
need for elaborate high and low temperature cooling water systems;</font></li>
<li><font face="Arial" size="4">Gas turbine lube oil is not exposed to the combustion
process, resulting in very low lube oil consumption and eliminating the need
for extensive lube oil conditioning systems;</font></li>
<li><font face="Arial" size="4">Gas turbines operate on MDO, obviating the need
for fuel bunker heating, fuel line tracing and fuel conditioning systems.<br>
</font><font face="Arial"> </font> </li>
</ul>
<p><b><font face="Arial" size="5">Disadvantages of Marine Aero-derivative Gas
Turbines</font></b></p>
<p><font face="Arial" size="4">Thermal efficiency:<br>
</font></p>
<ul>
<li><font face="Arial" size="4">Gas turbine thermal efficiency is lower than
the thermal efficiency of comparable diesel engines. Thermal efficiency of
aero derivative gas turbines in the 20 - 30 MW class ranges from 36.5 to 40%.
This makes the single cycle fuel consumption of a gas turbine about 20% higher
than that of a caparable diesel engine;</font></li>
<li><font face="Arial" size="4">Gas turbine thermal efficiency is proportional
to gas turbine output. Thermal efficiency of small gas turbines, in the 2
- 5 MW class, hardly exceeds 30%;</font></li>
</ul>
<p><font face="Arial" size="4">Liquid fuel quality restrictions:</font></p>
<ul>
<li><font face="Arial" size="4">Gas turbines can operate on either gaseous fuel
or liquid fuel or both simultaneously, without any restriction in the ratio
between fuels. However there are some severe restrictions on the quality of
the liquid fuel. Vanadium and sulfur content should be kept within the specified
limits in order to avoid high temperature corrosion of the turbine blades,
which leads to loss of engine performance. In practice, the fuel specification
completely rule out the use of any residual fuel and the cheaper distillates
as well. ISO 8317-1996 Class F Marine Fuels MDO-DMA and DMX are suitable,
but DMA might be a bit high on Sulfur. </font></li>
</ul>
<p><font face="Arial" size="4">Initial investments:<br>
</font></p>
<ul>
<li><font face="Arial" size="4">Initial investment for a gas turbine engine
in the 20 - 30 MW class is approximately 15 - 20% higher than in diesel engines
of comparable output. For smaller gas turbines, especially derivatives of
helicopter engines, the price difference is even higher;</font></li>
</ul>
<p><font face="Arial" size="4">All the above reasons might spell doom for many
a marine gas turbine project. An rightly so, if the advantages do not offset
the disadvantages of the use of gas turbines, the vessel will be an economic
disaster. </font><font face="Arial" size="4">When the first series of gas turbines
for cruise vessels were contracted in the late 1990s, some people temporarily
lost their sense of perspective. All kinds of projects traditionally featuring
diesels as prime movers, were suddenly re-engined with gas turbines of all makes
and sizes. None of them made it through the project phase. Many of these projects
failed because of the low thermal efficiency of smaller gas turbines. Even projects
involving large gas turbines failed, mainly because of the high specific fuel
consumption of the gas turbine and high fuel cost. With residual fuels usually
being between USD. 60 and USD. 100 cheaper per ton than MDO and diesels being
20% more fuel efficient, single cycle gas turbines have a hard time competing.</font></p>
<p></p>
<p><b><font face="Arial" size="5">Gas Turbine Myths and Misunderstandings</font></b></p>
<p><font face="Arial" size="4">In the marine community there are still a lot of
myths and misunderstandings about gas turbines.</font></p>
<p><font face="Arial" size="4">Myth: <br>
Gas turbines have very low torque and cannot be used in mechanical drive applications.</font></p>
<p><font face="Arial" size="4">Fact:<br>
Gas turbines can develop a very high torque, be</font><font face="Arial" size="4">cause
the gas generator is aero-dynamically coupled to the free power turbine. This
allows the gas generator to spin up even when the free power turbine is stationary
because moment of inertia of the propeller. When the gas generator develops
sufficient air flow, the torque of the free power turbines overcomes the inertia
of propeller.<br>
</font></p>
<p><font face="Arial" size="4">Myth:<br>
Gas turbines are unable to take instant load application.</font></p>
<p><font face="Arial" size="4">Fact:<br>
The design of the gas turbine, with the gas generator aero-dynamically coupled
to the free power turbine, lends itself very well to instant application of
heavy loads, which occur when a generator suddenly trips off-line. The speed
of the free power turbine might drop momentarily, but the gas generator will
generate sufficient airflow to correct free power turbine speed almost instantly.
</font></p>
<p><font face="Arial" size="4">Myth:<br>
Gas turbines only run on jet fuel.</font></p>
<p><font face="Arial" size="4">Fact:<br>
Gas turbines are perfectly happy to run on any liquid fuel available, as long
as the combustion properties are all right. Technically it is possible to burn
well seperated residual fuels. However, commonly available residual fuels have
high contents of Sulfur, Vanadium and alkali metals. The marine liquid fuel
specifications of the gas turbine manufacturers have been compiled to ensure
satisfactory hot section replacement intervals. Distillate fuels, such as MDO
DMX and DMA (ISO-8217:1996(E), Category ISO-F) are acceptable, provided the
Sulfur content is below 1.0%. Higher Sulfur and alkali metals content will reduce
hot section lifetime accordingly. Vanadium content is given as 0.5 ppm maximum
to reach a satisfactory lifetime. Higher Vanadium content will accellerate high
temperature corrosion of the turbine blades. The replacement cost of a prematurely
worn hot section will definitely offset the gains of using non-compliant fuels.</font></p>
<p><b><font face="Arial" size="5">Marine Gas Turbine Applications</font></b></p>
<p><font face="Arial" size="4">There are indeed some commercial marine applications
in which gas turbines perform very well:</font></p>
<p><font face="Arial" size="4">Fast ferries: <br>
</font></p>
<ul>
<li><font face="Arial" size="4">Low weight and small size of gas turbines, as
well as simple arrangement of ancillary systems, leave more space for revenue
making purposes;</font></li>
<li><font face="Arial" size="4">High gas turbine output makes it possible to
satisfy high speed required. In some cases one fast ferry can replace two
conventional ferries.</font><font face="Arial" size="4"><br>
</font></li>
</ul>
<p><font face="Arial" size="4">Cruise vessels:<br>
</font></p>
<ul>
<li><font face="Arial" size="4"> Combined cycle operation reduces specific fuel
consumption to more competitive levels. Usually one gas turbine can service
the power requirements of the entire vessel;</font></li>
<li><font face="Arial" size="4">Lower engine room space requirements allow for
an increase in passenger capacity within the same dimensions;</font></li>
<li><font face="Arial" size="4">Low noise and vibration enhance passenger comfort;</font></li>
<li><font face="Arial" size="4">No visible smoke makes operations in Alaskan
water possible;</font></li>
<li><font face="Arial" size="4">Low NOx and SOx emissions allow operations in
environmentally sensitive areas.</font></li>
</ul>
<p><b><font face="Arial" size="5">Future Marine Gas Turbines Applications</font></b></p>
<p><font face="Arial" size="4">Future application of marine gas turbine could
very well be the following types of vessels:</font></p>
<p><font face="Arial" size="4">LNG carriers:<br>
</font></p>
<ul>
<li><font face="Arial" size="4"> The boil-off gas from the cargo tanks is ideal
fuel for gas turbines;</font></li>
<li><font face="Arial" size="4">The thermal efficiency of the gas turbine is
much higher than that of the steam turbines, currently in use;</font></li>
<li><font face="Arial" size="4">Because of its low weight and size, the gas
turbine requires a much smaller engine room. Cargo capacity can be increase
by up to 12% without increasing the dimensions of the vessel;</font></li>
<li><font face="Arial" size="4">The small impact on CG allow the gas turbine
power plant to be located on the main deck instead of on the tank top. This
provides a lot of flexibility in the arrangement of the vessel.<br>
</font></li>
</ul>
<p><font face="Arial" size="4">Seismic vessels:<br>
</font></p>
<ul>
<li><font face="Arial" size="4"> The low structure borne noise characteristics
of the gas turbine reduces noise in hydrophones;</font></li>
<li><font face="Arial" size="4">The high output of the gas allows for larger
streamers to be towed;</font></li>
<li><font face="Arial" size="4">Because of the small dimensions of the gas turbine,
more space onboard the vessel can be used for commercial purposes.</font></li>
</ul>
<p><b><font face="Arial" size="5">New and Overhauled Gas Turbine Parts</font></b></p>
<p><font face="Arial" size="4">MPT Consultancy has access to one of the world's
largest stocks of new and overhauled parts for the following gas turbines. We
offer a large range of parts at prices much below OEM list prices. </font></p>
<ul>
<li><font face="Arial" size="4">GE LM1500;</font></li>
<li><font face="Arial" size="4">GE LM1600;</font></li>
<li><font face="Arial" size="4">GE LM2500;</font></li>
<li><font face="Arial" size="4">GE LM5000;</font></li>
<li><font face="Arial" size="4">GE LM6000;</font></li>
<li><font face="Arial" size="4">RR / Allison K501;</font></li>
<li><font face="Arial" size="4">P&W GG3;</font></li>
<li><font face="Arial" size="4">P&W GG4;</font></li>
<li><font face="Arial" size="4">P&W FT4;</font></li>
<li><font face="Arial" size="4">P&W FT8.</font></li>
</ul>
<p><font face="Arial" size="4">If you have problems finding the right parts for
your engine, please contact us for a very competitive offer. </font></p>
<p><font face="Arial" size="4">We also buy your surplus spares inventory. </font></p>
<p><font face="Arial" size="4">For more information, contact Alexander Harsema-Mensonides,
general manager.<br>
Mobile phone +46 70 587 5796<br>
E-mail <a href="mailto:gtparts@mptconsult.com">gtparts@mptconsult.com</a></font></p>
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