Combined cycle power plant having serial heat exchangers

A combined cycle power plant (CCPP) comprising:

• a gas turbine system, a steam turbine, and a heat recovery steam generator (HRSG), the HRSG including a high-pressure economizer (HPECON), wherein a first feed water supply line extends from an outlet of the HPECON and out of the HRSG, and wherein the gas turbine system comprises:
• a gas turbine having a compressor section, a turbine section, and a combustor section disposed downstream from the compressor section and upstream from the turbine section, the combustor section in fluid communication with a fuel supply via a fuel supply line;
• a water circuit fluidly coupled and extending between the first feed water supply line and a return water line, the water circuit comprising a first water line extending between the first feed water supply line and the return water line;
• an extraction-air line extending between an inlet port on the compressor section and an outlet port on the turbine section;
• a first heat exchanger thermally coupling the first water line to the extraction-air line transferring heat from a flow of extraction-air within the extraction-air line to a flow of water within the water circuit;
• and
• a second heat exchanger thermally coupling the first water line to the fuel supply line for transferring heat from the flow of water within the water circuit to a flow of fuel within the fuel supply line, wherein the second heat exchanger is disposed immediately downstream from the first heat exchanger such that all water from the first heat exchanger enters the second heat exchanger.