Chapter 13 Gas Turbine Power Plants

Air In
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Figure 13.7 Gas turbine plant with reheat and power turbine
i.e., a power turbine as shown in Figure 13.7, or both turbines and
the compressor may be connected to a common shaft. In either
case the reheat process is thermodynamically the same; it appears
as process 04'-05 in Figure 13.8.
It is clear from (13.13) that turbine work is directly proportional
to the turbine inlet temperature. For the two turbines in series,
as shown in Figure 13.7, there are two turbine inlet temperatures,
viz., T 03 and T 05 . The reheat combustor raises the temperature
Tos to a very high level, perhaps as high as T03. The result is
an increase in the specific work for the L.P. turbine.
By incorporating reheat and regeneration in the same gasturbine
cycle one can increase power and efficiency at the same
time. A similar improvement can be made in the compressor
work. From (13.12) we observe that the compressor work is directly
proportional to the inlet temperature T 0] . By installing two
stages of compression with intercooling between the stages, we