Page 118 - Advanced Gas Turbine Cycles

90 Advanced gas turbine cycles

6.2.2. The recuperative STIG plant

Consider next a recuperative STIG plant (Fig. 6.5, again after Lloyd [2]). Heat is again
recovered from the gas turbine exhaust: but firstly in a recuperator to heat the compressed
air, to state 2A before combustion; and secondly in an HRSG, to raise steam S for injection
into the combustion chamber.
Again we analyse the open cycle version of this plant, but with a fuel inputf' (per unit
air flow) at ambient temperature To, i.e. a fuel enthalpy flux off'hfo. For the combustion
chamber we may now write
ha2A +fhfO + Shlih = (1 +f)hg.l + Sh3, (6.10)
and for the parallel calorific value experiment, at temperature To = T,,

ha0 +fho = f[CVI" + (1 +f)h,, (6.1 I)
Subtracting Eq. (6. I 1) from Eq. (6.10) yields
ha2A - ha0 +frcvlo = (1 +fMg3 - hgo) + S(k3 - hsfA (6.12)

(6.13)

6 4
I1
AIR 7
RECUPERATOR
2

STEAM
HRSG

EXHAUST

Fig. 6.5. STIG plant with additional gadair recuperator.