Modular turbomachine inner and outer casings with multi-stage steam extraction sites

Abstract

Various embodiments include methods and apparatuses of forming turbomachine casing intermediate structures. In some embodiments apparatuses include a steam turbomachine casing intermediate structure including an inner shell having an external surface and inner shell cavity, and defining an opening for allowing fluid entry to the cavity and an outer shell having an internal surface, these surfaces defining at least one closed, axial-extending chamber, the inner shell and outer shells each having access regions adjacent the closed chamber, each of the access regions including a plurality of locations, selectable to be machined to create an exhaust slot or an exhaust opening in the inner casing or the outer casing, respectively, and wherein a structural integrity of the casing is uniform regardless of which of the axial locations are selected to be machined, where the exhaust opening is fluidly connected with the at least one closed chamber through the outer shell.

What is claimed is: 
     
         1 . A steam turbomachine casing intermediate structure comprising:
 an inner shell having an external surface, wherein a material of the inner shell defines an inner shell cavity, and wherein the material of the inner shell defines an opening for allowing fluid from a steam path of the turbomachine to enter the inner shell cavity; and   an outer shell having an internal surface, the internal surface of the outer shell and the external surface of the inner shell defining at least one closed chamber extending in an axial direction of the steam turbomachine,   the inner shell having a first access region adjacent the at least one closed chamber, the first access region including a plurality of inner shell axial locations, wherein at least one of the plurality of inner shell axial locations is selectable to be machined to create an exhaust slot for allowing fluid to exit the inner shell cavity and enter the at least one closed chamber, and wherein a structural integrity of the casing is uniform regardless of which of the inner shell axial locations is selected to be machined,   the outer shell having a second access region adjacent the at least one closed chamber, the second access region including a plurality of outer shell axial locations, wherein at least one of the plurality of outer shell axial location is selectable to be machined to create an exhaust opening fluidly connected with the at least one closed chamber through the outer shell and wherein the structural integrity of the casing is uniform regardless of which of the outer shell axial locations is selected to be machined.   
     
     
         2 . The steam turbomachine casing of  claim 1 , wherein the inner shell includes a first axial section and a second axial section separate from and complementary to the first axial section. 
     
     
         3 . The steam turbomachine casing of  claim 1 , wherein the exhaust slot allows extraction of a high pressure fluid from the inner shell at a location proximate a selected stage of the turbomachine, the location being related to a fluid characteristic. 
     
     
         4 . The steam turbomachine casing of  claim 1 , wherein the exhaust opening allows extraction of a high pressure fluid from the at least one closed chamber proximate a selected stage of the turbomachine. 
     
     
         5 . The steam turbomachine casing of  claim 1 , wherein the first and second access regions each have a uniform thickness, different from a thickness of the inner shell adjacent the first access region and different from a thickness of the outer shell adjacent the second access region. 
     
     
         6 . The steam turbomachine casing of  claim 5 , wherein the first access region has a thickness that is less than half a thickness of a remainder of the inner shell. 
     
     
         7 . The steam turbomachine casing of  claim 5 , wherein the second access region has a thickness that is less than half a thickness of a remainder of the outer shell. 
     
     
         8 . The steam turbomachine of  claim 1 , wherein the internal surface of the outer shell and the external surface of the inner shell define at least two closed chambers extending in an axial direction of the steam turbomachine. 
     
     
         9 . A steam turbomachine casing intermediate structure comprising:
 at least one shell casing defining at least one cavity and having a plurality of pre-formed extraction opening sites selectable for use, wherein a structural integrity of the at least one shell casing is uniform regardless of which of the plurality of pre-formed extraction opening sites is selected for use.   
     
     
         10 . The steam turbomachine casing intermediate structure of  claim 9 , wherein the at least one shell casing includes an inner shell casing and an outer shell casing, wherein the at least one cavity is defined by a material of the inner shell. 
     
     
         11 . The steam turbomachine casing intermediate structure of  claim 10 , wherein the inner shell casing includes a first axial section and a second axial section. 
     
     
         12 . The steam turbomachine casing intermediate structure of  claim 9 , wherein the pre-formed extraction opening site is selected for use based on a fluid characteristic of a fluid within the steam turbomachine during operation adjacent the selected opening site. 
     
     
         13 . A method of fabricating a steam turbomachine casing structure for a steam turbomachine, the method comprising:
 forming a casing inner shell having an external surface, wherein a material of the casing inner shell defines an inner shell cavity and a fluid opening for allowing fluid from a turbomachine steam path to enter the inner shell cavity; and   forming a casing outer shell having an internal surface such that the internal surface of the outer shell and the external surface of the inner shell define at least one closed chamber extending in an axial direction of the steam turbomachine;   forming, in the casing inner shell, a first access region adjacent the at least one closed chamber, the first access region including a plurality of inner shell axial locations, wherein at least one of the plurality of inner shell axial locations is selectable to be machined to create an exhaust slot for allowing fluid to exit the inner shell cavity and enter the at least one closed chamber, and wherein a structural integrity of the casing is uniform regardless of which of the inner shell axial locations is selected to be machined; and   forming, in the casing outer shell, a second access region adjacent the at least one closed chamber, the second access region including a plurality of outer shell axial locations, wherein at least one of the plurality of outer shell axial location is selectable to be machined to create an exhaust opening fluidly connected with the at least one closed chamber through the outer shell and wherein the structural integrity of the casing is uniform regardless of which of the outer shell axial locations is selected to be machined.   
     
     
         14 . The method of  claim 13 , wherein the forming of the casing inner shell includes:
 forming a first axial section; and   forming a second axial section, the second axial section being separate from and complementary to the first axial section.   
     
     
         15 . The method of  claim 13 , further comprising:
 machining a first slot through the first access region, wherein a location of the first slot is based upon a performance characteristics of the turbomachine; and   machining a first opening in the second access region, the first opening extending through the outer shell.   
     
     
         16 . The method of  claim 13 , wherein the forming of the casing inner shell and the forming of the casing outer shell are performed such that the outer surface of the casing inner shell and the inner surface of the casing outer shell define at least two closed chambers extending in an axial direction of the steam turbomachine. 
     
     
         17 . The method of  claim 16 , further comprising:
 machining a second slot through the first access region into a second of the at least two closed chambers while maintaining the structural integrity of the casing, a location of the second slot being based upon a performance characteristics of the turbomachine; and   machining a second opening in the second access region adjacent the second of the at least two closed chambers while maintaining the structural integrity of the casing, the second opening extending through the outer shell.   
     
     
         18 . The method of  claim 13 , wherein the forming of the first access region includes forming the first access region to have a uniform thickness, different from a thickness of the inner shell adjacent the first access region. 
     
     
         19 . The method of  claim 13 , wherein the forming of the second access region includes forming the second access region to have a uniform thickness, different from a thickness of the outer shell adjacent the second access region. 
     
     
         20 . The method of  claim 13 , wherein the forming of the first access region includes forming the first access region to have a thickness less than half a thickness of the remainder of the inner shell; and
 wherein the forming of the second access region includes forming the second access region to have a thickness less than half a thickness of a remainder of the outer shell.