Steam turbine rotor with mechanically coupled high and low temperature sections using different materials

Abstract

A turbine rotor including an elongated shaft having at least an HP region, the HP region having a first section supporting a stage 1 rotor wheel and a second section supporting a stage 2 rotor wheel, the first section formed of a relatively higher-temperature-capability material and the second section formed of a relatively lower-temperature-capability material. Various mechanical couplings and described for securing the first and second sections.

1 . A turbine rotor comprising:
 an elongated shaft including at least an HP region, the HP region having a first axial section supporting a stage 1 rotor wheel and a second axial section supporting a stage 2 rotor wheel, said first axial section formed of a relatively higher-temperature-capability material and said second axial section formed of a relatively lower-temperature-capability material; and   means for mechanically coupling said first axial section and said second axial section.   
     
     
         2 . The turbine rotor of  claim 1  wherein said relatively higher-temperature-capability material comprises a 12% Cr material. 
     
     
         3 . The turbine rotor of  claim 1  wherein said relatively lower-temperature-capability material comprises a CrMoV material. 
     
     
         4 . The turbine rotor of  claim 2  wherein said relatively lower-temperature-capability material comprises a CrMoV material. 
     
     
         5 . The turbine rotor of  claim 1  wherein said first axial section and said second axial section are coupled between said stage 1 and stage 2 rotor wheels. 
     
     
         6 . A turbine rotor comprising: an elongated shaft including at least HP and IP regions, a combined HP region having a first section supporting a stage 1 rotor wheel and a second section supporting a stage 2 rotor wheel, said first section formed of a relatively higher-temperature-capability material and said second section formed of a relatively lower-temperature-capability material; and
 wherein said first and second sections are joined by a mechanical coupling.   
     
     
         7 . The turbine rotor of  claim 7  wherein said mechanical coupling comprises abutting flanges on said first and second sections and plural bolts passing through said abutting flanges. 
     
     
         8 . The turbine rotor of  claim 7  wherein said mechanical coupling comprises a flange on said first section engaged with a hub of said stage 2 rotor wheel, and plural bolts passing through said flange and said hub. 
     
     
         9 . The turbine rotor of  claim 7  wherein said mechanical coupling comprises a reduced diameter end of one of said first and second sections received in a blind bore in the other of said first and second sections. 
     
     
         10 . The turbine rotor of  claim 7  wherein said mechanical coupling comprises a first bore through said first section and a second blind bore on said second section, with a stud extending between said first bore and said second blind bore. 
     
     
         11 . The turbine rotor of  claim 10  wherein said stud is threaded into said blind bore. 
     
     
         12 . The turbine rotor of  claim 6  wherein said mechanical coupling comprises a male spline extending from said second section and received in a female spline in said first section. 
     
     
         13 . The turbine rotor of  claim 12  wherein said male spline is formed with at least six radially projecting teeth that extend axially along said male spline. 
     
     
         14 . The turbine rotor of  claim 12  wherein said mail spline is formed with four radially projecting teeth, spaced substantially 90° apart about an axis of rotation of said turbine rotor. 
     
     
         15 . The turbine rotor of  claim 7  wherein said relatively higher temperature capability material comprises a 12% Cr material. 
     
     
         16 . The turbine rotor of  claim 7  wherein said relatively lower temperature capability material comprises a CrMoV material. 
     
     
         17 . The turbine rotor of  claim 15  wherein said relatively lower temperature capability material comprises a CrMoV material.