Page 348 - Subyek Teknik Mesin - Forsthoffers Best Practice Handbook for Rotating Machinery by William E Forsthoffer

Gas Turbine Best Practices Be st Practice 6.1

Fig 6.1.10 Mars gas turbine (Courtesy of Solar Turbines)

Fig 6.1.11 Gas turbine classifications (aero-derivative). Left: used as gas generator only (Courtesy of Dresser Rand). Right: entire engine adapted
(gas generator and power turbine). Note: power turbine is either turbo-prop or bypasss fan drive in aero-engine version (Courtesy of General Electric).

Figure 6.1.13. This produces 45 MW (60,000 ISO horsepower), Figure 6.1.18. Most modern gas turbines are of the triple shaft
has an efficiency of 43% and can drive a load on either or both design. Figure 6.1.19 shows a single shaft gas turbine where the
ends. gas generator and power turbine are mounted on the same shaft.
The advantages and disadvantages of aero-derivative gas tur- This figure also shows a dual shaft gas turbine, where the gas
bines are presented in Figure 6.1.14. generator and power turbine are mounted on different shafts.
Figure 6.1.15 shows a hybrid type gas turbine, which is Single shaft gas turbines are usually limited to generator drive
a combination of an aero-derivative gas generator and an in- applications, since the starting turbine load is significantly lower
dustrial power turbine. This design offers the advantage of for a generator application, because a generator is started under
maintainability on the ‘hot section’ of the gas turbine and high zero load. Dual shaft turbines are used for mechanical drive,
reliability in the power turbine. These facts are presented in pump and compressor applications.
Figure 6.1.16.
Aero-derivative and industrial facts are discussed in Gas turbine drive configurations
Figure 6.1.17.
Gas turbines can be designed as hot end drive, or cold end drive.
Figure 6.1.20 presents these facts. The majority of first and
The number of gas turbine shafts second generation gas turbines were of a hot end drive, but most
Gas turbines are configured as single, dual or triple shaft designs. third generation gas turbines are of the cold and dry type. A cold
The advantages and disadvantages of each type are presented in end drive configuration is more reliable, in my opinion, since the

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