Method and apparatus for mitigating out of roundness effects at a turbine

Abstract

A turbine and a method of mitigating out-of-roundness effects at a turbine is disclosed. An inner turbine shell and an outer turbine shell of the turbine is provided. The inner turbine shell is coupled to the outer turbine shell using a ring insert. The ring insert is segmented into a plurality of ring insert segments that reduce a transfer of load from the outer turbine shell to the inner turbine shell to mitigate out-of-roundness of the inner turbine shell.

1 . A method of mitigating out-of-roundness effects at a turbine, comprising:
 disposing an inner turbine shell of the turbine within an outer turbine shell of the turbine; and   coupling the inner turbine shell to the outer turbine shell using a ring insert that is segmented into a plurality of ring insert segments that reduce a transfer of load from the outer turbine shell to the inner turbine shell to mitigate out-of-roundness of the inner turbine shell.   
     
     
         2 . The method of  claim 1 , wherein the plurality of ring insert segments further comprises four ring insert segments. 
     
     
         3 . The method of  claim 2 , wherein at least one of the ring insert segments subtends an angle measured from a longitudinal axis of the inner turbine shell selected from the group consisting of: (i) less than 90 degrees; (ii) between about 15 degrees and about 85 degrees; and (iii) between about 30 degrees and about 70 degrees. 
     
     
         4 . The method of  claim 1 , further comprising using a processor to determine a length of the ring insert segments at which an out-of-roundness of the inner turbine shell meets a selected criterion. 
     
     
         5 . The method of  claim 1 , wherein a length of a ring insert segment is selected to reduce a load path between the outer turbine shell and the inner turbine shell. 
     
     
         6 . The method of  claim 1 , wherein the load is a result of a thermal stress at the outer turbine shell. 
     
     
         7 . The method of  claim 1 , wherein the ring insert segments are disposed at a thrust collar of the inner turbine shell at equidistant locations around a circumference of the inner turbine shell. 
     
     
         8 . The method of  claim 1 , wherein the inner turbine shell is formed of at least two azimuthal shell sectors. 
     
     
         9 . A turbine, comprising:
 an outer turbine shell;   an inner turbine shell; and   a ring insert configured to couple the inner turbine shell to the outer turbine shell and segmented into a plurality of ring insert segments to reduce a load transfer from the outer turbine shell to the inner turbine shell.   
     
     
         10 . The turbine of  claim 9 , wherein the ring insert is segmented into four ring insert segments. 
     
     
         11 . The turbine  claim 10 , wherein an angle subtended by at least one of the ring insert segments is selected from the group consisting of: (i) less than 90 degrees; (ii) between about 15 degrees and 85 degrees; and (iii) between about 30 degrees and about 70 degrees. 
     
     
         12 . The turbine  claim 9 , wherein a length of the ring insert segments is determined using a processor running a program of a model of the turbine. 
     
     
         13 . The turbine  claim 9 , wherein a length of the ring insert segments is selected to reduce a load path between the outer turbine shell and the inner turbine shell. 
     
     
         14 . The turbine of  claim 9 , wherein the load is related to thermal stress at the outer turbine shell. 
     
     
         15 . The turbine of  claim 9 , wherein the ring insert segments are evenly spaced around a circumference of the inner turbine shell. 
     
     
         16 . The turbine of  claim 9 , wherein the inner turbine shell is formed of at least two shell sectors extending over a selected azimuthal angle.