High temperature radially fed axial steam turbine

A method for operating a high temperature radially fed axial steam turbine having a rotatable rotor with a rotational axis and a circumferential surface;

• a casing enclosing the rotor so as to form an annular space between the rotor and the casing;
• axially distributed blade and vane rows mounted in the annular space on the rotor;
• a hot inlet duct for steam, that circumferentially extends around the rotor axis and has:
• a radial inlet end circumscribing the rotor;
• and an axial outlet end circumscribing the rotor and axially joined to the annular space immediately upstream of the blade and vane rows, the method comprising:
• receiving a cold steam via a cold inlet spiral circumferentially extending around the rotor axis to circumferentially distribute the cold steam, a cold inlet duct for the cold steam being connected at an inlet end to a downstream end of the cold inlet spiral and being axially displaced from the hot inlet duct such that the hot inlet duct is between the cold inlet duct and blade and vane rows, the cold inlet duct having an outlet end, in the hot inlet duct, that circumscribes the rotor and is configured to provide a boundary layer of cold steam over the circumferential surface between the outlet end of the cold inlet duct and the blade and vane rows, wherein the rotor circumferential surface between the cold inlet duct outlet end and the blade and vane rows is configured to promote and maintain the boundary layer;
• and
• simultaneously injecting the cold steam through the hot inlet duct and a hot steam through the cold inlet duct, wherein a temperature of the cold steam is less than a temperature of the hot steam.