Power generation system exhaust cooling

A turbomachine system, comprising:

• a gas turbine system including a compressor component, a combustor component, and a turbine component;
• a shaft driven by the turbine component;
• a fan coupled to the shaft upstream of the gas turbine system for drawing in an excess flow of air through an air intake section;
• a mixing area for receiving an exhaust gas stream produced by the gas turbine system;
• an air extraction system for:
• extracting at least a portion of the excess flow of air generated by the fan to provide bypass air;
• and diverting the bypass air into the mixing area to reduce a temperature of the exhaust gas stream;
• the air extraction system including an air splitting system comprising:
• an outer bypass duct for diverting the bypass air around the gas turbine system into the mixing area to reduce the temperature of the exhaust gas stream in the mixing area, wherein the outer bypass duct comprises an arrangement of axially extending ducts, the axially extending ducts arrayed circumferentially around the gas turbine system to surround the gas turbine system;
• and
• an inner passage for directing any non-extracted portion of the excess flow of air into the compressor component of the gas turbine system to supercharge the gas turbine system;
• an airflow controller for controlling the air extraction system to maintain the reduced temperature exhaust gas stream at a temperature of less than about 900° F.;
• and
• a selective catalytic reduction (SCR) system for processing the reduced temperature exhaust gas stream from the mixing area.

A power generation system, comprising:

• a gas turbine system including a compressor component, a combustor component, and a turbine component;
• a shaft driven by the turbine component;
• an electrical generator coupled to the shaft for generating electricity;
• a fan coupled to the shaft upstream of the gas turbine system for drawing in an excess flow of air through an air intake section;
• a mixing area for receiving an exhaust gas stream produced by the gas turbine system;
• an air extraction system for:
• extracting at least a portion of the excess flow of air generated by the can to provide bypass air;
• and diverting the bypass air into the mixing area to reduce a temperature of the exhaust gas stream;
• the air extraction system including an air splitting system comprising:
• an outer bypass duct for diverting the bypass air around the gas turbine system into the mixing area to reduce the temperature of the exhaust gas stream in the mixing area, wherein the outer bypass duct comprises an arrangement of axially extending ducts, the axially extending ducts arrayed circumferentially around the gas turbine system to surround the gas turbine system;
• and
• an inner passage for directing any non-extracted portion of the excess flow of air into the compressor component of the gas turbine system to supercharge the gas turbine system;
• an airflow controller for controlling the air extraction system to maintain the reduced temperature exhaust gas stream at a temperature of less than about 900° F.;
• and
• a selective catalytic reduction (SCR) system for processing the reduced temperature exhaust gas stream.