GB776847A - Gas-cooled gas turbine - Google Patents

Abstract

776,847. Turbines. SULZER FRERES SOC. ANON. May 13, 1955 [May 20, 1954], No. 13847/55. Class 110 (3). A multi-stage axial flow turbine in which a protective cooling gas is introduced into a labyrinth packing in the gap between the shroud ring or the equivalent of a stator blade ring and the walls of the rotor to prevent working fluid passing through the gap and to cool the surface of the rotor and in which the radial distance of the gap from the axis of the rotor is approximately the same as that of the inner ends of adjacent rotor blades has the part of the labyrinth packing lying upstream of the point of entry of the protective cooling gas arranged with a smaller resistance to flow of the cooling gas than the part downstream thereof. The hot working medium is supplied to the turbine through an annular space 1 to an annular flow channel 2. The stator guide blades 3, 4 fixed in a casing 5 have shroud rings 9 provided with labyrinth sealing rings 10 to form gaps 11, 12. Protective cooling gas which may be taken from the compressor of the gas turbine unit is led into a space 13 formed between the stator casing 5 and housing 14. A part of this gas is led to the roots of the guide blades 3 by bores 17, 18 in the casing 5. Bores 21, 22 supply another part of this air into the labyrinth gap 12. The bore 21 also constitutes a metering orifice which is so dimensioned that in normal operation a part of the protective gas issues from the gap 12 upstream of the blades 4. To maintain these conditions, the number of labyrinth rings downstream of the bore 22 is greater than the number upstream. Another part of the gas passes through a metering channel 23 into a collecting chamber 24 whence it is led through channel 25 into the labyrinth gap 11. Some of this gas passes into the working fluid upstream of the blades 3. The channels 22 and bores 23 should be distributed around the circumference of the casing.