Page 129 - Advanced Gas Turbine Cycles

Chapter 6. 'Wet' gas turbine plants 101

Fig. 6.14. Recuperated water injection (RWI) plant and humidified air turbine (HAT) plant compared (after
Macchi et al. [9]).

6.4.2.4. The CHATcycle
A modification of the HAT cycle has been proposed by Nakhamkin [l 11, which is
known as the cascaded'humid air turbine (CHAT). The higher pressure ratios required in
humidified cycles led Nakhamkin to propose reheating between the HP and LP turbines.
Splitting the expansion in this way is paralleled by splitting the compression, and enables
the HP shaft to be non-generating, as indicated in Fig. 6.15. This implies that the capital
cost of the plant can be reduced, but the cycle is still complex.

6.4.2.5. The TOPHAT cycle
Another water injection cycle proposed is the TOPHAT cycle [12] (see Fig. 6.16). As
for the HAT cycle, the purpose is to introduce water into the cycle with low exergy loss
and this is achieved by injecting water continuously in the compressor in an attempt to