alcor30 (Mechanical) (OP)
28 Dec 07 13:48
my colleagues and myself are working on the design of a combined cycle powerplant. It is a repowering project. The gas turbine is a state-of-the-art model but the bottoming cycle will re-utilize existing equipments inherited from an older thermal power station from the 70's (steam turbine, pumps, etc...)
Gas module of the combustion turbine will include a so-called gas performance heater.
Function of this gas heater is to raise gas temperature upstream of the injection in the combustor nozzles, basically to optimise Combined Cycle overall efficiency. The gas heater is a heat exchanger fed by hot water bleeded from the HRSG.
Design of the gas performance heater appears to be a challenging issue because, in some situations, the pressure of the hot IP water available from our HRSG may exceed the "design pressure" of the gas performance heater currently proposed by the turbine manufacturer.
Hot IP water available from the HRSG may reach up to 200 bar(g) = 2901 psi ... which is significantly higher than the design pressure of the gas heater (currently 110 barg = 1015 psi).
According to the gas turbine manufacturer, the gas performance heater may be redesigned to withstand high pressure conditions imposed by our project. But, in any case, the GT manufacturer warns that a such a project specific re-design would have a significant cost impact...
I would really appreciate to have advises/recommandations to best handle this design issue...
especially if you have already been facing similar problems with gas heaters on previous projects.
What is the typical cost augmentation we should expect if we were to redesign the gas performance heater to withstand high pressure up to 200 barg (2900 psi) ?
Best wishes to you all.