Method and apparatus for achieving power augmentation in gas turbine using wet compression

A process for changing shaft power production from a gas turbine unit that comprises a compressor for compressing a stream of intake air supplied thereto and discharging compressed air, a high-pressure combustion chamber in which fuel is combusted with the compressed air discharged from said compressor, a high-pressure turbine driven by hot combustion air discharged from said high-pressure combustion chamber, a low-pressure combustion chamber in which fuel is combusted with the expanded combustion air discharged from said high-pressure turbine, and a low-pressure turbine driven by the hot combustion air discharged from said low-pressure combustion chamber, the process comprising:

• operating said compressor with a pressure ratio larger than 15 bar;
• injecting liquid droplets into the stream of intake air using at least one liquid droplet injection device disposed on an upstream side of said compressor to increase shaft power generated by the gas turbine unit;
• controlling the at least one liquid droplet injection device so that responsive to a desired increase of shaft power output, the at least one liquid droplet injection device delivers the liquid droplets to reach a discrete rate of mass flow within 60 seconds;
• and
• adjusting the fuel mass flow with a fuel control valve in order to maintain firing temperatures of the gas turbine unit, wherein the at least one liquid droplet injection device is operable with an on/off-control signal, and wherein the fuel control valve is controllable as a function of liquid droplet injection using a single feed forward signal synchronized to the on/off-control signal.