Sealing of nozzles in a steam turbine

Abstract

Nozzle segments mounting vanes are received in circumferentially extending, generally dovetail-shaped grooves in an outer casing of a steam turbine, the nozzle segments forming part of a stage with rotating buckets of the steam turbine. The inclined slashfaces of the adjoining bases of the nozzle segments are provided with circumferentially opening slots to receive spline seals. The spline seals preclude or minimize steam leakage flow past the gap between the adjoining nozzle segments thereby enhancing the steam flow through the partitions of the nozzles.

1 . A steam turbine comprising: 
 a steam turbine stage including a plurality of circumferentially spaced buckets carried by a steam turbine rotor in a steam path through the steam turbine stage;    a support surrounding the rotor including a plurality of nozzle segments carrying a plurality of nozzles and forming another part of the stage of the steam turbine, each said nozzle segment including a dovetail-shaped base carrying at least one stator vane forming at least part of said nozzle;    said support having a circumferentially extending, radially inwardly opening, dovetail-shaped groove and receiving the dovetail-shaped bases of said nozzle segments, each said stator vane extending from said base in a radially inward direction;    each of said segment bases having endfaces respectively in circumferential registry with opposed endfaces of circumferentially adjacent segment bases, said endfaces including slots opening generally circumferentially and generally in registration with one another; and    a spline seal extending between each of said opposed endfaces of circumferentially adjacent segment bases and in said slots for minimizing or precluding steam leakage flow from the steam path past said registering endfaces.    
   
   
       2 . A turbine according to  claim 1  wherein each said spline seal extends generally in generally axial and generally circumferential directions for sealing against steam leakage flows in generally radial directions.  
   
   
       3 . A turbine according to  claim 1  wherein each said spline seal extends in a generally inclined radial outward downstream direction for sealing against steam leakage flows in a generally axial direction.  
   
   
       4 . A turbine according to  claim 1  wherein each spline seal extends generally in axial and circumferential directions for sealing against steam leakage flows in generally radial directions and a second spline seal extending between each of said opposed endfaces of circumferentially adjacent segments, said second spline seals extending generally in inclined radial outward downstream directions for sealing against steam leakage flows in a generally axial direction.  
   
   
       5 . A turbine according to  claim 1  wherein said support has a circumferentially extending groove having an axially extending hook, each said segment having a hook for radially overlying the segment hook, said spline seals extending generally in axial and circumferential directions for sealing against steam leakage flows in generally radial directions.  
   
   
       6 . A turbine according to  claim 1  wherein said support has a circumferentially extending groove having an axially extending hook, said spline seals extending generally in inclined radial outward downstream directions for sealing against steam leakage flows in a generally axial direction.  
   
   
       7 . A turbine according to  claim 1  wherein said spline seals include a cloth surrounding each said spline seal along opposite sides thereof and about at least a pair of opposite edges thereof.  
   
   
       8 . A turbine according to  claim 1  wherein each said spline seal comprises a seal body having an enlargement along opposite edges and received in said slots with the enlargements adjacent bases of said slots, respectively.  
   
   
       9 . A turbine according to  claim 8  wherein said seal body is formed of sheet metal, said enlargements comprising integral bent margins of said sheet metal spline seal having edges facing central portions of said sheet metal spline.