"Recent Applications and Future Trends in Marine Gas Turbines"
David L. LUCK*
Recent marine projects have extended the range of applications in both naval and commercial marine markets for GE's LM aeroderivative gas turbines. Future trends will lead to improved power system components, and will advance marine power capability through extension of system concepts.
Gas turbines have become firmly established for marine propulsion applications over the last 20 years, including extensive use in military vessels, and growing application in specific segments of the commercial marine market. The development of aeroderivative gas turbines, i.e. those derived from flying engines, has made efficient engines with a proven track record of operation available for use in a variety of ship classes. Table 1 provides the marine specifications of GE's complete line of LM aeroderivative gas turbines.
Recent applications have expanded the use and range of gas turbines in both the commercial and military marine markets. Currently 27 international navies use 968 engines on 388 ships. In the commercial marine arena, 82 GE LM gas turbines can be found on 45 ships, in various hull configurations and in both mechanical and electric drive propulsion systems
3. COMMERCIAL APPLICATIONS
Gas turbines have only recently been put to serious use in commercial ships, as the compact, low weight characteristics of the engines have satisfied an urgent need. The development of the fast ferry market (generally vessels carrying over 50 passengers at over 25 knot speed) created a growing sector of volume sensitive ships carrying low density cargo, such as passengers and cars, which need compact and light weight propulsion systems. Similarly, cruise ships place a premium on efficient use of internal ship volume, and represent a growing opportunity for gas turbine use. Commercial ship propulsion configurations also include CODAG (Combined Diesel And Gas Turbine), where the diesels and gas turbines independently drive waterjets, allowing simultaneous operation of both prime mover types. Multiple gas turbines are also used in the CODAG configuration. Higher rated gas turbines offer extended capability in both commercial configurations.
3.1 Royal Caribbean/Celebrity Cruise Ships
The cruise industry has embraced gas turbine technology for both main propulsion and on-board power generation. In June 2000, the world's first gas turbine-powered cruise ship began commercial operation.
Over 80% reduction in exhaust emissions is just one benefit to cruise ship owners of a COmbined Gas turbine and steam turbine integrated Electric drive System (COGES) based on GE's environmentally friendly LM2500+ aeroderivative gas turbines. Four Royal Caribbean International and four Celebrity Cruises cruise ships will use the COGES scheme.
A COGES arrangement is a very efficient use of energy: Energy that otherwise would be lost in the exhaust from the gas turbines is captured to produce steam from boilers for the steam turbines (see Figure 1).
The gas turbine-based system powers electric motors that move the ship through the water. The COGES configuration also provides for all on-board power requirements such as ventilation systems, power to light cabins, etc.
Table 2 provides a summary of the benefits of a COGES ship using GE's compact gas turbines.
The LM2500+ COGES ship operates on clean distillate fuel to significantly reduce emissions of most airborne pollutants and other particulates compared to a diesel-electric power system operating on heavy fuel oil, which is customary for most cruise ships. Gas turbines meet all current and expected emission requirements, without the modifications required of large diesel engines.
The high power density of the compact GE aeroderivative LM2500+ gas turbines enables the power plant to be installed in much less space than a diesel-electric system. This arrangement frees space for up to 50 additional passenger cabins on each Royal Caribbean International and Celebrity Cruises ship, plus additional space for crew cabins and public areas.
Cabin revenue from space made available by the smaller COGES power plant more than offsets the cost of clean distillate fuel, making a COGES ship economically and environmentally attractive.
* Manager, Marine Applications and Ship Integration
GE Marine Engines One Neumann Way
MD S156 Cincinnati, Ohio U.S.A. 45215
Tel: (513) 552-5387
Fax: (513) 552-5005