Combined power generation system with feedwater fuel preheating arrangement

A combined power generation system comprising:

• a gas turbine configured to combust fuel to generate a rotational force;
• a heat recovery steam generator (HRSG) configured to heat feedwater using combustion gas discharged from the gas turbine and include a high-pressure section, a medium-pressure section, and a low-pressure section with different pressure levels;
• a fuel preheater configured to heat fuel supplied to the gas turbine and include a primary heating part and a secondary heating part;
• and
• a high-pressure feedwater supply pipe connected to the high-pressure section to supply high-pressure feedwater to the fuel preheater;
• a feedwater transfer pipe connecting the secondary heating part and the primary heating part to supply the feedwater discharged from the secondary heating part to the primary heating part;
• a feedwater temperature control pipe connected to a downstream side of a medium-pressure pump of the medium-pressure section to supply first medium-pressure feedwater to the feedwater transfer pipe;
• and
• a feedwater pressure control pipe connected to the medium-pressure section to supply second medium-pressure feedwater to the feedwater transfer pipe, the second medium-pressure feedwater having a higher temperature than that of the first medium-pressure feedwater,
• wherein the high-pressure feedwater supply pipe is connected to the secondary heating part to supply the high-pressure feedwater to the secondary heating part,
• wherein the medium-pressure section includes the medium-pressure pump pressurizing and supplying the feedwater, a medium-pressure economizer receiving the feedwater from the medium-pressure pump and heating the received feedwater, and a medium-pressure drum storing the feedwater heated in the medium-pressure economizer,
• wherein the feedwater temperature control pipe is connected between the medium-pressure pump and the medium-pressure economizer to receive the feedwater from the medium-pressure pump,
• wherein the feedwater pressure control pipe is connected between the medium-pressure economizer and the medium-pressure drum to receive the feedwater heated in the medium-pressure economizer,
• wherein the feedwater of the feedwater pressure control pipe is configured to flow either in a direction toward the medium-pressure section or in a direction toward the feedwater transfer pipe, such that a pressure of the feedwater transfer pipe and a pressure of the upstream side of the medium-pressure drum are controlled to be equal to each other by the feedwater pressure control pipe.

A combined power generation system comprising:

• a gas turbine configured to combust fuel to generate a rotational force;
• a heat recovery steam generator (HRSG) configured to heat feedwater using combustion gas discharged from the gas turbine and include a high-pressure section, a medium-pressure section, and a low-pressure section with different pressure levels;
• a fuel preheater configured to heat fuel supplied to the gas turbine and include a primary heating part and a secondary heating part;
• and
• a high-pressure feedwater supply pipe connected to the high-pressure section to supply high-pressure feedwater to the fuel preheater,
• wherein the primary heating part and the secondary heating part are disposed in parallel such that fuel in the primary heating part does not flow to the secondary heating part and fuel in the secondary heating part does not flow to the primary heating part,
• wherein the fuel preheater further comprises a preheater connected to a feedwater return pipe to receive the feedwater discharged from the primary heating part and the secondary heating part disposed in parallel, the fuel heated in the preheater being divided and supplied to the primary heating part and the secondary heating part disposed in parallel.