Inlet air heating systems for combined cycle power plants

A combined cycle power plant, comprising:

• a gas turbine system including an inlet housing for receiving ambient air;
• a heat recovery steam generator (HRSG) in fluid communication with the gas turbine system, the HRSG receiving exhaust gas from the gas turbine system;
• a steam turbine in fluid communication with the HRSG, the steam turbine receiving steam generated by the HRSG using the exhaust gas from the gas turbine system;
• a condenser in fluid communication with the steam turbine, the condenser receiving exhaust steam from the steam turbine;
• and
• an inlet air heating system in communication with the inlet housing of the gas turbine system and in communication with the condenser, the inlet air heating system including:
• a plurality of heating coil assemblies at least partially positioned within the inlet housing of the gas turbine system;
• a vent valve in fluid communication with each of the plurality of heating coil assemblies, the vent valve allowing air to flow into and out of the plurality of heating coil assemblies when in an open position;
• a supply line in fluid communication with the plurality of heating coil assemblies, the supply line providing water to the plurality of heating coil assemblies;
• a hot water line in fluid communication with the supply line and one of the HRSG or a conduit positioned downstream of a condenser, the hot water line providing hot water to the supply line;
• and
• a drain line in fluid communication with the plurality of heating coil assemblies and the condenser, the drain line providing the water from the plurality of heating coil assemblies to the condenser, further comprising:
• a condensate pump in fluid communication with the condenser, the condensate pump removing the water included in the condenser;
• a deaerator in fluid communication with the condensate pump, the deaerator receiving the water from the condensate pump and removing at least one gas from the water;
• and
• a forwarding pump in fluid communication with the deaerator and the HRSG, the forwarding pump providing the water from the deaerator to the HRSG, wherein the inlet air heating system further comprises:
• a discharge line in fluid communication with the plurality of heating coil assemblies, the discharge line receiving the water directly from the plurality of heating coil assemblies;
• a control valve fluidly coupling the discharge line and the drain line to provide the water from the discharge line to the drain line;
• and
• a return line fluidly coupled to the control valve, the return line receiving the water from the discharge line via the control valve, and providing the water to one of:
• a first conduit fluidly coupling the condenser and the condensate pump, or
• a second conduit fluidly coupling the deaerator and the forwarding pump.