Page 354 - Subyek Teknik Mesin - Forsthoffers Best Practice Handbook for Rotating Machinery by William E Forsthoffer

Gas Turbine Best Practices Be st Practice 6.2

Since gas turbine performance varies as a function of fuel and
inlet conditions, a set of standardized conditions has been
established by ISO (International Standards Organization) to
rate all gas turbines.
ISO standard conditions are:
T inlet = 15°C (59°F) Relative humidity = 0%
P inlet = sea level Design speed of rotors
Inlet and exhaust Power losses = 0
losses = 0" H 2 O Compressor bleed air = 0
Based on stated fuel
heating value

Fig 6.2.4 Gas turbine performance ISO conditions

Fig 6.2.5 Gas turbine performance ISO and site performance (Reprinted with permission of Turbomachinery International Handbook 1993, Vol. 34, No. 3)

A given engine design limits air volume flow capacity.
Produced power is a function of actual energy extracted per
pound of vapor and mass flow of vapor.
For a given engine therefore, produced power varies directly
with inlet air density.
Produced power does become limited by low volume (stall and
surge) flow.

Fig 6.2.6 The effect of inlet air density on produced power and heat
rate

Care must be taken when selecting gas turbines to ensure
sufficient shaft power is available at:
High temperature conditions
Fouled inlet conditions
Gas turbine applications tend to be ‘fully loaded’ since gas
turbines (unlike steam turbines) are not custom designed.

Fig 6.2.7 Gas turbine performance effect of inlet conditions on Fig 6.2.8 Typical gas turbine output power and heat rate vs.
performance ambient temperature

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