Gas Turbine Handbook : Principles and Practices

186 Gas Turbine Handbook: Principles and Practices
where ‘x=3’ is the axial location for the compressor discharge on
single spool gas turbines.
Exhaust Gas Temperature Corrected = EGT/Θ = T 7
/Θ
where ‘x=7’ is the axial location for the turbine exhaust on dual spool
gas turbines.
In the following discussions parameter changes are all measured
at constant power. Correcting all parameters to the ISO Standard
eliminates the variables due to daily and seasonal fluctuations in
ambient temperature and pressure.
In electric power generation applications electric power is easily
determined as follows 2 :
P e =3.6
K h
t w (12-1)
where
K h
= watt-hours/meter disk revolution
t w
= seconds/meter disk revolution
In applications where a process compressor is driven by a single
shaft gas turbine, power is determined by the heat balance on a
driven process compressor (the load).
P = W g
(h i
– h o
) – Q r
– Q m
(12-2)
where
P = power input to the load device, Btu/sec
W g
= weight flow of gas entering the process compressor, lb/sec
h i
= enthalpy of gas entering the process compressor, Btu/lb
h o
= enthalpy of gas exiting the process compressor, Btu/lb
Q r
= radiation and convection heat loss from the process compressor
casing, Btu/sec
Q m
= mechanical bearing losses for the bearings of the process
compressor, Btu/sec
For free power turbine configurations, regardless of the applica-