New High Efficiency Simple Cycle Gas Turbine LMS100

Abstract
GE has introduced the first modern production gas turbine in the power generation industry to employ off-engine intercooling technology with the use of an external heat exchanger, the LMS100™. This gas turbine provides the highest simple cycle efficiency in the Industry today and comes on the heels of GE’s introduction of the highest combined cycle gas turbine system, the MS9001H. The LMS100™ system combines frame and aeroderivative gas turbine technology for gas fired power generation. This marriage provides customers with cyclic capability without maintenance impact, high simple cycle efficiency, fast starts, high availability and reliability, at low installed cost.

The unique feature of this system is the use of intercooling within the compression section of the gas turbine, leveraging technology that has been used extensively in the gas and air compressor industry. Application of this technology to gas turbines has been evaluated by GE and others extensively over many years although it has never been commercialized for large power generation applications. In the past five years, GE has successfully used the SPRINT® patented spray intercooling, evaporative cooling technology between the low and high pressure compressors of the LM6000™ gas turbine, the most popular aeroderivative gas turbine in the 40 to 50MW range. GE’s development of high pressure ratio aircraft gas turbines, like the GE90®, has provided the needed technology to take intercooling to production. The LMS100™ gas turbine intercooling technology provides outputs above 100MW, reaching simple cycle thermal efficiencies in excess of 46%. This represents a 10% increase over GE’s most efficient simple cycle gas turbine available today, the LM6000™.

Introduction
GE chose the intercooled cycle to meet customers’ need for high simple cycle efficiency. The approach to developing an intercooled gas turbine is the result of years of intercooled cycle evaluation along with knowledge developed with operation of SPRINTâ technology. Matching current technology with customer requirements results in a system approach to achieving a significant improvement in simple cycle efficiency.

The development program requirement was to use existing and proven technology from both GE Transportation (formerly GE Aircraft Engines) and GE Energy (formerly GE Power Systems), and combine them into a system that provides superior simple cycle performance at competitive installed cost. All component designs and materials, including the intercooler system, have been successfully operated in similar or more severe applications. The combination of these components and systems for a production gas turbine is new in the power generation industry.

The GE Transportation CF6-80C2/80E gas turbine provided the best platform from which to develop this new product. With over 100 million hours of operating experience in both aircraft engines and industrial applications, through the LM6000™ gas turbine, the CF6® gas turbine fits the targeted size class. The intercooling process allowed for a significant increase in mass flow compared to the current LM™ product capability. Therefore, GE Energy frame units were investigated for potential Low Pressure Compressors (LPC) due to their higher mass flow designs. The MS6001FA (6FA) gas turbine compressor operates at 460 lbm/sec (209 kg/sec) and provides the best match with the CF6-80C2 High Pressure Compressor (HPC) to meet the cycle needs.

The LMS100™ system includes a 3-spool gas turbine that uses an intercooler between the LPC and the HPC as shown in Fig. 1.

FIG 1: LMS100 GT Configuration
FIG 1: LMS100 GT Configuration

Intercooling provides significant benefits to the Brayton cycle by reducing the work of compression for the HPC, which allows for higher pressure ratios, thus increasing overall efficiency. The cycle pressure ratio is 42:1. The reduced inlet temperature for the HPC allows increased mass flow resulting in higher specific power. The lower resultant compressor discharge temperature provides colder cooling air to the turbines, which in turn allows increased firing temperatures at metal temperatures equivalent to the LM6000™ gas turbine producing increased efficiency. The LMS100™ system is a 2550°F (1380°C) firing temperature class design.

FIG 2: LMS100 Gas Turbine
FIG 2: LMS100 Gas Turbine

This product is particularly attractive for the peaking and mid-range dispatch applications
where cyclic operation is required and efficiency becomes more important with increasing dispatch. With an aeroderivative core the LMS100™ system will operate in cyclic duty without maintenance impact. The extraordinary efficiency also provides unique capability for cogeneration applications due to the very high power-to-thermal energy ratio. Simple cycle baseload applications will benefit from the high efficiency, high availability, maintainability and low first cost. GE, together with its program participants Avio, S.p.A., Volvo Aero Corporation and Sumitomo Corporation, are creating a product that changes the game in power generation.

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