Dual orifice bypass system for dual-fuel gas turbine

Apparatus for controlling the temperature of compressor discharge air supplied in a purge mode during gas fuel operation and in an atomizing air mode during liquid fuel operation in a dual-fuel gas turbine, comprising:

• a heat exchanger for placing the compressor discharge air in heat exchange relation with a cooling medium at an inlet temperature to the heat exchanger lower than a temperature of the compressor discharge air for extracting heat from the compressor discharge air;
• a valve for controlling the flow of the cooling medium through the heat exchanger;
• first and second bypass flow passages connected in parallel on opposite sides of said flow control valve, each bypass flow passage having an orifice enabling a predetermined flow therethrough;
• a bypass valve in said second flow passage;
• said bypass valve being open in said atomizing air mode, enabling flow of the cooling medium through said first and second bypass flow passages and orifices and being closed in said purge mode, preventing flow through said second bypass passage.