Steam Turbine

Abstract

A steam turbine ( 10 ), especially in the form of a double-flow low-pressure steam turbine, includes a rotor ( 11 ) which is rotatably mounted around an axis ( 21 ) and which is concentrically enclosed with a spacing by an inner casing ( 13 ), forming annular steam passages ( 28, 29 ), and which has a multiplicity of rotor blades ( 12 ) which project into the steam passages ( 28, 29 ), wherein the inner casing ( 13 ) supports a multiplicity of stator blades ( 12 ) which project into the steam passages ( 28, 29 ) and which, for feeding steam to the steam passages ( 28, 29 ), has an inlet duct ( 15 ) which is directed around the axis ( 21 ) and tapers in the flow cross section. With such a steam turbine, the production is simplified by the inner casing ( 13 ) being formed as a welded construction, in which blade carriers ( 14 ), which delimit the steam passages ( 28, 29 ) and are produced as cast parts, are welded to additional forged or rolled steel elements ( 20 ) for fastening the stator blades ( 12′ ).

1 . A steam turbine comprising:
 a rotor rotatably mounted around an axis;   an inner casing which concentrically encloses the rotor with a spacing, the spacing forming annular steam passages;   a multiplicity of rotor blades projecting into the steam passages; and   a multiplicity of stator blades supported by the inner casing and projecting into the steam passages;   wherein the inner casing includes an inlet duct for feeding steam to the steam passages directed around the axis and tapers in the flow cross section;   wherein the inner casing is a welded construction and comprises cast blade carriers which delimit the steam passages, and additional forged or rolled steel elements supporting the blade carriers, for fastening the stator blades.   
   
   
       2 . The steam turbine as claimed in  claim 1 , wherein the inlet duct, which tapers in the flow cross section, comprises an inlet scroll. 
   
   
       3 . The steam turbine as claimed in  claim 1 , further comprising:
 a plurality of steam extraction chambers formed in the inner casing, and wherein the steam extraction chambers are formed or delimited by the blade carriers and the steel elements which are connected to them.   
   
   
       4 . The steam turbine as claimed in  claim 1 , further comprising:
 support rings arranged concentrically to the axis with axial spacing and supporting the blade carriers on their rear side, the support rings stiffening the inner casing;   tie rods between the support rings configured and arranged to absorb transverse forces; and   wherein the steel elements are welded to the support rings.   
   
   
       5 . The steam turbine as claimed in  claim 4 , wherein the tie rods are welded or screwed to the support rings. 
   
   
       6 . The steam turbine as claimed in  claim 1 , further comprising:
 at least one radial guide vane arranged in the inlet duct.   
   
   
       7 . The steam turbine as claimed in  claim 1 , wherein the blade carriers are formed of nodular cast iron or cast steel. 
   
   
       8 . The steam turbine as claimed in  claim 1 , wherein the steam turbine is a double-flow low-pressure steam turbine.