ith the increased demand for natural gas, liq-uefied natural gas (LNG) is getting a second

look as a fuel option in the United States, Europeand South America. As LNG development and oper-

ational costs continue to decline, the need remains forreliable gas turbines to drive LNG production compressors. Nowthe choice has broadened with GE’s LM6000 aeroderivative gas tur-bine, an ideal driver for refrigerant compressors.

LNG Production: A Brief LookWhen natural gas deregulation took hold in the mid-1970s,

sparking the availability of natural gas reserves, LNG productiongreatly decreased. However, with the current heightened interest inenergy matters, LNG production is increasing.

For example, LNG accounts for about 1 percent of the U.S. nat-ural gas supply. The 220 Bcf of LNG imported into the U.S. in 2000is small compared to the more than 21 Tcf of gas that was consumedin the U.S. in 2000.1

Currently only two LNG import terminals are in operation inthe U.S.: the Distrigas facility in Everett, MA and the Trunklinefacility in Lake Charles, LA. Maximum sustainable LNG importcapacity at these two facilities in 1999 was assumed to be 352Bcf. Two additional facilities, one at Cove Point, MD and theother at Elba Island, GA (currently idled), are expected to reopenin 2003, adding 529 Bcf of sustainable capacity. According toannounced plans, it is further assumed that Elba Island willreceive one to two shipments (less than 5 Bcf) to test the facilityprior to it being fully reactivated.2

The cost to produce LNG has dropped about 30 percent in thepast 10 years, making this fuel a viable and economic choice. LNGis also attractive in countries that lack pipeline infrastructures. InIndonesia, Malaysia and Australia, for example, LNG is processed inliquefaction plants and shipped by tanker to regasification andpower generation facilities primarily in Japan, South Korea andTaiwan. LNG is also available throughout the Caribbean, SouthAmerica and Euro-pean countries such as Spain and France.3

LM6000 Aeroderivative Gas TurbineLNG production is an extremely demanding environment that

relies on the regular delivery of fuel in order for the process to beprofitable. In the past, frame gas turbines or steam turbines were thepower choice for many LNG production facilities. However, GE’sLM6000 gas turbine for mechanical drive service offers numerousbenefits to LNG producers.

With output greater than 50,000 shaft horsepower (shp),aeroderivative gas turbines such as the LM6000 are capable ofhandling variable speeds at varied loads. This flexibility is demon-

Ideal Driver

Aeroderivative Gas Turbine Provides Efficient Power For LNG Processing

by Tayo Montgomery, GE IndustrialAeroDerivative Gas Turbines,

Evendale, OH

Table 1GE LM6000 Gas Turbine Mechanical Drive Specifications*

Power output (shp) 60,000

Heat rate-LHV (Btu/shp-hr) 5980

Exhaust gas temperature (oF) 853

Exhaust gas flow (lb/s) 280

Number of shafts 2

Pressure ratio 28.5

Shaft speed (rpm) 3600

Base plate enclosure dimensions 30' 6" L x 13' 9" W x 14' 6" H

* 59oF, 60% relative humidity, sea level, no inlet/exhaust losses on gas fuel with no NOx - media

Figure 2

54 Pipeline & Gas Journal/October 2001/pipelineandgasjournalonline.com

begin rotation of the high-pressure rotor. Once the combustion sys-tem has ignited, this rotor can generate significant starting torque tobegin rotation of the low-pressure rotor as well as the driven equip-ment, whether a generator rotor or compressor train, without theneed for additional helper motors (see Figures 3a and 3b).

The BenefitsThe LM6000 is one of the world’s most efficient simple cycle

gas turbine. It remains a popular favorite with a wide variety ofindustrial and power generation customers throughout the world.As of June 2001, 454 LM6000 engines had been shipped, with 283of those in operation (152 are LM6000PC/PD engines with a totalof 1.24 million operating hours).

The gas turbine offers users high reliability and availability. Forinstance, the LM6000 fleet will accumulate 5 million hours in serv-ice by the end of 2001, with the high-time engine logging morethan 70,000 hours. The high-time LM6000PC/ PD engine has accu-mulated in excess of 33,000 hours in operation.

With the overall high efficiency in excess of 40 percent comes a

Figure 1: Results from GE’s LM6000 Variable Speed Tests.

Figure: 3a

Figure: 3b

Circle #14256 Pipeline & Gas Journal/October 2001/pipelineandgasjournalonline.com

strated on every flight by the engines aboard commercial andmilitary aircraft from which aeroderivative gas turbines arederived.

The LM6000 was first introduced as the PA model inDecember 1992, using a single annular combustion system withfew changes from the world’s most successful aircraft enginefor wide-body airframes—the CF6-80C2. At the same time, GEbegan development of Dry Low Emissions (DLE) technologies,culminating in the LM6000PB model introduced in December1994. As the LM6000 fleet approached the one million-hourmark, with an installed base of over 100 engines, GE consis-tently obtained availability above 97 percent. The next stepwas to increase power by 6.5 percent to 43.5 megawatts andefficiency by 2 to 42 percent.

The launch of GE’s LM6000PC/PD aeroderivative gas turbinewas announced in 1996 and the first unit went into commercialoperation in a power generation application in late 1997. Themechanical drive version of this gas turbine has been availablesince early 1998.

The LM6000 opens an entirely new business opportunity,with interest being paced by applications requiring variablespeed drivers with outputs greater than 50,000 shp. Table 1 pro-vides an overview of LM6000 performance specifications.

Although some exploratory interest was generated when theLM6000 mechanical drive version was first announced, signifi-cantly greater interest within both gas compression and marineapplications has been expressed since June 2000—especiallywith increasing energy prices.

Typical applications for the LM6000 are new designs of largeoil and gas production facilities, for gas reinjection, transmis-sion, processing and liquefaction. GE is supporting severalongoing application studies using the LM6000 as the driver.

GE Oil & Gas in Florence, Italy is currently developing anLM6000 mechanical drive package to serve these expandedmarket requirements. This GE Power Systems business offersextensive experience designing, manufacturing and testing reli-able mechanical drive packages for GE’s complete line of LMgas turbines.

As a world leader in compression and turbogenerators prod-ucts and services, GE Oil & Gas serves the oil and gas, LNG,pipeline, refinery and petrochemical industries.

Thorough TestingGE conducted thorough testing on the LM6000 PC/PD

model. Phase 1 tested the power generation (constant speed)operation, with engine performance and mechanical integritybeing the primary focuses. Phase 2 commenced in June 1997and addressed the mechanical drive operation, with the focus-es being on low pressure turbine aerodynamics, variable speedoperation, and confirmation of speed-load characteristics. Phase3 focused on gas and liquid fuel DLE operation, including emis-sions characteristics and variable load operation.

A test sequence was then conducted on the LM6000PC engine.The test engines used more than 1,300 instruments, includingtemperature rakes, accelerometers, strain gauges, thermocouples,and pressure transducers. Both static and rotating instrumentationwas used.

This machine completed all development testing in 1997.Operation up to 53 megawatts output was evaluated, and no fail-ures, unexpected results or limitations were encountered at anypoint in the test program. Performance, margins, and all other testresults were as predicted. Detailed component design studieswere carried out including confirmation that blade frequenciesand modes were well within established design practices of GE’scomplete line of aeroderivative gas turbines. Figure 1 shows theresults of the LM6000 mechanical drive testing.

There are no hardware differences on an LM6000PC gas tur-bine for power generation or the mechanical drive applications,with the exception of variable inlet guide vanes. These compo-nents are identical to those used in the DLE version and arerequired to allow for variable speed operation (see Figure 2).

A primary advantage of the LM6000 is its starting torque capa-bility. As a two-rotor machine, the LM6000 uses a 200 hp starter to

reduction in CO2 emissions. That meansLNG producers will see one-third less CO2emissions per horsepower generated withan aeroderivative gas turbine versus aframe unit.

Other advantages of the LM6000include:

� Variable speed from 50 to 105 per-cent of design speed;

� Compact, lightweight, modular design; � Rapid maintenance and repair turn-

around offered through GE’s experi-enced service technicians; and

� DLE capability for emissions reductionto 25 ppm NOx and 25 ppm CO.

ConclusionGE continues to support several appli-

cation studies in the LNG industry whereits LM6000 aeroderivative gas turbine canbe a cost-effective driver. P&GJ

Tayo Montgomery is the LM6000Technical Sales Manager with GEIndustrial AeroDerivative Gas Turbines inEvendale, OH.

REFERENCES 1 “Terminal Fever,” Power Engineering, May 20012 “Assumptions to the Annual Energy Outlook, Oil& Gas Energy Module”,www.eia.doe.gov/oiaf/aeo/assumption/oil_gas.html 3 “Infrastructure needed for global gas delivery,”Power, May/June 2001