METHOD FOR COOLING A GAS TURBINE AND GAS TURBINE FOR CONDUCTING SAID METHOD

The Invention relates to a method for cooling a gas turbine (10), which comprises a turbine (15), wherein a rotor (11), which rotates about a machine axis, carries a plurality of rotating blades (17), which are mounted on said rotor (11) by means of blade roots and extend with their airfoils into a hot gas path of said gas turbine (10), wherein said rotor (11) is concentrically surrounded by a turbine vane carrier (13) carrying a plurality of stationary vanes (16), whereby said rotating blades (17) and said stationary vanes (16) are arranged in alternating rows in axial direction. An extended lifetime with external cooling is achieved by providing first and second cooling systems (A, B) for said turbine (15), whereby said first cooling system (A) uses cooling air of a first pressure and first temperature and said second cooling system (B) uses cooling air of a second pressure and second temperature substantially smaller than said first pressure and first temperature, and whereby said first cooling system (A) is used to cool the airfoils of said rotating blades (17) and said turbine vane carrier (13) and said stationary vanes (16), and whereby said second cooling system (B) is used to cool said rotor (11) and said blade roots of said rotating blades (17) in at least one row of said rotating blades (17).