Regenerative fuel heating system

A combined cycle cogeneration power plant comprising:

• a source of combustion fuel;
• a combustion turbine including:
• a fuel inlet for receiving combustion fuel,
• an air inlet for receiving air,
• a combustor for burning said combustion fuel and said air, and
• an outlet through which hot gaseous combustion product can be released;
• a regenerative fuel heating system coupled to said source of combustion fuel, and including:
• at least one heat exchanger for transferring heat to said combustion fuel for heating said combustion fuel prior to receipt of said combustion fuel at said fuel inlet, and
• at least one modulating control valve at said at least one heat exchanger for controlling temperature of said combustion fuel;
• a heat recovery steam generator (HRSG) connected to said outlet of said combustion turbine for receiving said hot gaseous combustion product, said HRSG including:
• at least one heat exchanger including at least one steam/water drum having at least one surface blowdown connection, at least one evaporator connected to the at least one steam/water drum, and at least one economizer,
• a water inlet connected with the at least one heat exchanger of the HRSG,
• a steam outlet, and
• a stack for releasing said hot gaseous combustion product;
• a steam turbine having a steam inlet for receiving steam from the steam outlet of the HRSG, and an exhaust steam outlet from the said steam turbine;
• a condenser connected to said exhaust steam outlet of said steam turbine for condensing steam to a liquid condensate;
• and
• at least one pump for supplying water to said HRSG;
• wherein said at least one heat exchanger in the regenerative fuel heating system includes:
• at least one high pressure high temperature (HPHT) shell-and-tube heat exchanger with an inlet and an outlet, at least one intermediate pressure intermediate temperature (IPIT) shell-and-tube heat exchanger with an inlet and an outlet,
• at least one low pressure low temperature (LPLT) shell-and-tube heat exchanger with an inlet and an outlet;
• and
• said at least one modulating control valve is arranged to control flow of said saturated liquid from said at least one surface blowdown connection, and is positioned at an outlet of said at least one heat exchanger of said regenerative fuel heating system, and wherein said at least one modulating control valve maintains said saturated liquid close to liquid phase.

A combined cycle cogeneration power plant comprising:

• a source of combustion fuel;
• a combustion turbine including:
• a fuel inlet for receiving combustion fuel,
• an air inlet for receiving air,
• a combustor for burning said combustion fuel and said air, and
• an outlet through which hot gaseous combustion product can be released;
• a regenerative fuel heating system coupled to said source of combustion fuel, and including:
• at least one heat exchanger for transferring heat to said combustion fuel for heating said combustion fuel prior to receipt of said combustion fuel at said fuel inlet, and
• at least one modulating control valve at said at least one heat exchanger for controlling temperature of said combustion fuel;
• a heat recovery steam generator (HRSG) connected to said outlet of said combustion turbine for receiving said hot gaseous combustion product, said HRSG including:
• at least one heat exchanger including at least one steam/water drum having at least one surface blowdown connection, at least one evaporator connected to the at least one steam/water drum, and at least one economizer,
• a water inlet connected with the at least one heat exchanger of the HRSG,
• a steam outlet, and
• a stack for releasing said hot gaseous combustion product;
• a steam turbine having a steam inlet for receiving steam from the steam outlet of the HRSG, and an exhaust steam outlet from the said steam turbine;
• a condenser connected to said exhaust steam outlet of said steam turbine for condensing steam to a liquid condensate;
• and
• at least one pump for supplying water to said HRSG;
• wherein said at least one surface blowdown connection discharges saturated liquid from said at least one steam/water drum and is connected to said at least one heat exchanger of said regenerative fuel heating system;
• and
• wherein said at least one surface blowdown connection further includes a bypass line connected directly to a flash tank for bypassing said at least one heat exchanger of said regenerative fuel heating system in an emergency operating mode.