Patent Publication Number: US-11035256-B2

Title: Steam turbine system

Description:
TECHNICAL FIELD 
     The present invention relates to a steam turbine system. 
     This application claims priority based on JP 2017-137198 filed in Japan on Jul. 13, 2017, of which the contents are incorporated herein by reference. 
     BACKGROUND ART 
     In a power generation plant, a steam turbine system including a steam turbine is used. The steam turbine is provided with a turbine rotor configured to rotate, an inner casing, and an outer casing. 
     The inner casing includes, in an upper portion thereof, a steam introduction port into which steam is introduced. The inner casing houses the turbine rotor. The outer casing houses the inner casing. The outer casing guides the steam that worked in the inner casing to the outside. The outer casing is in a vacuum state. 
     Among steam turbines, there is known a steam turbine system of a side condenser type in which a condenser is disposed on a first side in a lateral direction of the outer casing (refer to Patent Document 1, for example). 
     The outer casing disclosed in Patent Document 1 includes a bottom plate, a ceiling plate, a curved plate, a pair of end plates, and an exhaust port. 
     The ceiling plate is disposed above the bottom plate, facing the bottom plate. The curved plate is disposed facing the exhaust port. The curved plate is integrally formed with one end of the ceiling plate and one end of the base plate. 
     The pair of end plates are disposed sandwiching the curved plate, the ceiling plate, and the bottom plate from an axial line direction of the turbine rotor. An opening for inserting the turbine rotor is formed in each of the pair of end plates. 
     In the steam turbine system disclosed in Patent Document 1, the steam that worked in the steam turbine is supplied to the condenser via the exhaust port formed on the first side in the lateral direction of the outer casing. 
     In a steam turbine system configured in this manner, it is possible to lower the height of a building and a level of a foundation and reduce cost compared to a steam turbine that discharges steam in the downward direction. 
     CITATION LIST 
     Patent Document 
     Patent Document 1: JP 2015-124634 A 
     SUMMARY OF INVENTION 
     Technical Problem 
     However, in the steam turbine system disclosed in Patent Document 1, as described above, an interior of the outer casing is in a vacuum state and may therefore become recessed due to the effect of external pressure. 
     Additionally, when a portion of the outer casing deforms in a direction toward the exhaust port by the steam in the outer casing being discharged from the exhaust port, there is a possibility of displacement of the outer casing and the inner casing in the lateral direction toward the exhaust port. 
     Therefore, an object of the present invention is to provide a steam turbine system capable of suppressing deformation of an outer casing and suppressing displacement of the outer casing and an inner casing in a lateral direction toward an exhaust port. 
     Solution to Problem 
     In order to solve the above-described problems, a steam turbine system according to an aspect of the present invention includes a steam turbine provided with a rotor that rotates about an axial line and extends in a horizontal direction, an inner casing that houses the rotor and allows steam to be introduced therein, and an outer casing that houses the inner casing, is provided with an exhaust port on a first side in a lateral direction, and is in a vacuum state in an interior thereof; a condenser disposed on the first side in the lateral direction of the outer casing and supplied with the steam via the exhaust port; and a first support rod provided inside the outer casing and extending in one direction. The outer casing includes an end plate facing the inner casing in an axial line direction serving as an extending direction of the axial line of the rotor, a ceiling plate disposed above the inner casing, extending along a horizontal plane, and connected to the end plate, a bottom plate disposed below the ceiling plate, extending along the horizontal plane, and connected to the end plate, and a curved plate facing the exhaust port in a direction intersecting the axial line, protruding in a direction separating from the exhaust port, and connected to an end of the ceiling plate and an end of the bottom plate disposed on a second side in the lateral direction of the outer casing, as well as the end plate. The first support rod includes a first end connected to a surface, of an inner surface of an upper half of the end plate, positioned on the first side in the lateral direction of the axial line, and a second end connected to an inner surface of the ceiling plate disposed further on the second side in the lateral direction of the outer casing than the first end. 
     According to the present invention, with provision of the first support rod having the configuration described above, the first support rod functions as a brace (support bar) between the inner surface of the end plate and the inner surface of the ceiling plate, making it possible to suppress deformation of the outer casing (specifically, the end plate and the ceiling plate) in which the interior is in a vacuum state. 
     Further, with provision of the first support rod having the configuration described above, when deformation occurs in which the end plate becomes recessed due to a pressure on an outer side of the outer casing being higher than a pressure inside the outer casing, a force resulting from the deformation of the end plate can be transmitted to the ceiling plate connected to the second end of the first support rod via the first end of the first support rod. 
     At this time, because the second end of the first support rod is disposed further on the second side in the lateral direction of the outer casing than the first end of the first support rod, the force transmitted to the ceiling plate includes a lateral component that acts in a direction from the first side in the lateral direction toward the second side in the lateral direction of the outer casing, and an upward component that acts in a direction that pushes the curved plate upward. 
     Thus, with the upward component of the force transmitted to the ceiling plate, it is possible to suppress deformation in which the ceiling plate becomes recessed due to the pressure on the outer side of the outer casing. 
     Further, a force generated when the steam inside the outer casing is discharged via the exhaust port (specifically, the force that attempts to move the outer casing and the inner casing in a direction from the second side in the lateral direction toward the first side in the lateral direction of the outer casing) can be weakened by the lateral component of the force transmitted to the ceiling plate. 
     That is, with provision of the first support rod having the configuration described above, deformation of the outer casing is suppressed, making it possible to suppress displacement of the outer casing and the inner casing in the lateral direction toward the exhaust port. 
     Further, the steam turbine system according to an aspect of the present invention described above may further include a second support rod provided inside the outer casing, extending in one direction, and including a first end connected to a surface, of the inner surface of the upper half of the end plate, positioned on the second side in the lateral direction of the axial line, and a second end connected to an inner surface of the curved plate positioned above the first end of the second support rod such that the second support rod is parallel with a vertical direction of the outer casing when viewed in an axial line direction. 
     Thus, with provision of the second support rod having the configuration described above, the second support rod functions as a brace between the inner surface of the end plate and the inner surface of the curved plate, making it possible to suppress deformation of the outer casing (specifically, the end plate and the curved plate) in which the interior is in a vacuum state. 
     Further, with provision of the second support rod having the configuration described above, when deformation occurs in which the end plate becomes recessed due to the pressure on the outer side of the outer casing being higher than the pressure inside the outer casing, a force resulting from the deformation of the end plate can be transmitted to an upper portion of the curved plate via the second support rod. 
     At this time, because the second support rod is disposed parallel with the vertical direction of the outer casing when viewed in the axial line direction, the force transmitted to the curved plate includes a lateral component that acts in a direction parallel with the axial line direction, and an upward component that acts in a direction that pushes the curved plate upward. 
     Accordingly, the force transmitted by the second support rod to the curved plate does not include a component that acts in the direction from the second side in the lateral direction toward the first side in the lateral direction (a component that moves the outer casing and the inner casing to the exhaust port side). As a result, displacement (displacement in the lateral direction) of the outer casing and the inner casing to the exhaust port side caused by provision of the second support rod can be suppressed. 
     Further, the steam turbine system according to an aspect of the present invention may further include a third support rod provided inside the outer casing and extending in one direction. The outer casing may face the curved plate in a direction intersecting the axial line, and further include a side plate connected to an end of the ceiling plate and an end of the bottom plate disposed on the first side in the lateral direction, as well as the end plate. The third support rod may include a first end connected to an inner surface of the side plate, and a second end connected to an inner surface of the ceiling plate positioned on the second side in the lateral direction of the first end of the third support rod. 
     With provision of the third support rod having the configuration described above, the third support rod functions as a brace between the inner surface of the side plate and the inner surface of the ceiling plate, making it possible to suppress deformation of the outer casing (specifically, the side plate and the ceiling plate) in which the interior is in a vacuum state. 
     Further, with provision of the third support rod having the configuration described above, when deformation occurs in which the side plate becomes recessed toward the curved plate side due to the pressure on the outer side of the outer casing being higher than the pressure inside the outer casing, a force resulting from the deformation of the side plate can be transmitted to the ceiling plate connected to the second end of the third support rod via the first end of the third support rod. 
     At this time, the force transmitted to the ceiling plate includes a lateral component that acts in a direction from the first side in the lateral direction toward the second side in the lateral direction of the outer casing, and an upward component that acts in a direction that pushes the ceiling plate upward. 
     Thus, with the upward component of the force transmitted to the ceiling plate, it is possible to suppress deformation in which the ceiling plate becomes recessed due to the pressure on the outer side of the outer casing. 
     Further, a force generated when the steam inside the outer casing is discharged via the exhaust port (specifically, the force that attempts to move the outer casing and the inner casing in a direction from the second side in the lateral direction toward the first side in the lateral direction of the outer casing) can be weakened by the lateral component of the force transmitted to the ceiling plate. 
     That is, with provision of the third support rod having the configuration described above, deformation of the outer casing is suppressed, making it possible to suppress displacement of the outer casing and the inner casing in the lateral direction toward the exhaust port. 
     Further, the steam turbine system according to an aspect of the present invention described above may further include a turbine frame disposed below the outer casing and configured to fix the bottom plate, and a fourth support rod provided inside the outer casing, extending in one direction, and including a first end connected to a surface, of an inner surface of a lower half of the end plate, positioned on the second side in the lateral direction of the axial line of the rotor, and a second end disposed further on the second side in the lateral direction of the outer casing than the first end of the fourth support rod and connected to an inner surface of the curved plate positioned below the first end of the fourth support rod. 
     However, in a state in which the bottom plate of the outer casing is fixed to the turbine frame, a fixed portion of the bottom plate of the outer casing and the turbine frame is a constraint point. Then, moments centered on the constraint point are generated in the outer casing in this state. 
     Specifically, a moment is generated in a direction from bottom to top on the curved plate side, a moment is generated in a direction from top to bottom on the exhaust port side, and a moment is generated in a direction from the second end in the lateral direction toward the first end in the lateral direction on the ceiling plate side. 
     With provision of the fourth support rod having the configuration described above, when deformation occurs in which the end plate becomes recessed in the axial line direction of the rotor due to the pressure on the outer side of the outer casing being higher than the pressure inside the outer casing, a force resulting from the deformation of the end plate can be transmitted to the lower portion of the curved plate connected to the second end of the fourth support rod via the first end of the fourth support rod. 
     At this time, the force transmitted to the lower end of the curved plate includes a lateral component that acts in a direction from the first side in the lateral direction toward the second side in the lateral direction, and a downward component that acts in a direction that pushes the curved plate downward. 
     Thus, with the downward component of the force transmitted to the lower portion of the curved plate, it is possible to suppress deformation in which the lower portion of the curved plate becomes recessed, and offset a portion of the moment in the direction from bottom to top generated on the curved plate side. 
     Further, a force generated when the steam inside the outer casing is discharged via the exhaust port (specifically, the force that attempts to move the outer casing and the inner casing in a direction from the second side in the lateral direction toward the first side in the lateral direction of the outer casing) can be weakened by the lateral component of the force transmitted to the lower portion of the curved plate. 
     That is, with provision of the fourth support rod having the configuration described above, deformation of the outer casing is suppressed, making it possible to suppress displacement of the outer casing and the inner casing in the lateral direction toward the exhaust port. 
     Further, the steam turbine system according to an aspect of the present invention described above may further include a turbine frame disposed below the outer casing and configured to fix the bottom plate, and a fifth support rod provided inside the outer casing and extending in one direction. The outer casing may include a reinforcement rib that protrudes upward from the bottom plate and includes an opposing surface facing an inner surface of the end plate. The fifth support rod may include a first end connected to a surface, of an inner surface of a lower half of the end plate, on the first side in the lateral direction of the axial line, and a second end connected to the opposing surface of the reinforcement rib positioned further on the second end side in the lateral direction of the outer casing than the first end of the fifth support rod, and above the first end of the fifth support rod. 
     With provision of the fifth support rod having the configuration described above, the fifth support rod functions as a brace between the inner surface of the end plate and the opposing surface of the reinforcement rib, making it possible to suppress deformation of the outer casing (specifically, the end plate) in which the interior is in a vacuum state. 
     Further, with provision of the fifth support rod having the configuration described above, when the end plate is deformed, becoming recessed toward the rotor, due to the pressure on the outer side of the outer casing being higher than the pressure inside the outer casing, a force resulting from the deformation of the end plate can be transmitted to the reinforcement rib connected to the second end of the fifth support rod via the first end of the fifth support rod. 
     At this time, the force transmitted to the reinforcement rib includes a lateral component that acts in a direction from the first side in the lateral direction toward the second side in the lateral direction, and an upward component that acts in a direction that pushes the reinforcement rib upward. 
     Thus, it is possible to reduce the moment in the direction from the top to the bottom that occurs on the exhaust port side by the upward component of the force transmitted to the reinforcement rib. 
     Further, a force generated when the steam inside the outer casing is discharged via the exhaust port (specifically, the force that attempts to move the outer casing and the inner casing in a direction from the second side in the lateral direction toward the first side in the lateral direction of the outer casing) can be weakened by the lateral component of the force transmitted to the reinforcement rib. 
     That is, with provision of the fifth support rod having the configuration described above, deformation of the outer casing is suppressed, making it possible to suppress displacement of the outer casing and the inner casing in the lateral direction toward the exhaust port. 
     Further, in the steam turbine system according to an aspect of the present invention described above, the fifth support rod may be inclined more gently than an inclination of the fourth support rod when viewed in the axial line direction. 
     Thus, by making the inclination of the fifth support rod more gentle than the inclination of the fourth support rod, it is possible to efficiently reduce the moments generated on the curved plate side and the exhaust port side. 
     In order to solve the above-described problems, a steam turbine system according to an aspect of the present invention includes a steam turbine provided with a rotor that rotates about an axial line and extends in a horizontal direction, an inner casing that houses the rotor and allows steam to be introduced therein, and an outer casing that houses the inner casing, is provided with an exhaust port on a first side in a lateral direction, and is in a vacuum state in an interior thereof; a condenser disposed on the first side in the lateral direction of the outer casing and supplied with the steam via the exhaust port; a turbine frame that supports the outer casing; and a first support rod provided inside the outer casing and extending in one direction. The outer casing includes an end plate facing the inner casing in an axial line direction serving as an extending direction of the axial line of the rotor, a ceiling plate disposed above the inner casing, extending along a horizontal plane, and connected to the end plate, a bottom plate disposed below the ceiling plate, extending along the horizontal plane, and connected to the end plate, and a curved plate facing the exhaust port in a direction intersecting the axial line of the rotor, protruding in a direction separating from the exhaust port, and connected to an end of the ceiling plate and an end of the bottom plate disposed on a second side in the lateral direction of the outer casing, as well as the end plate. The first support rod includes a first end connected to a surface, of an inner surface of a lower half of the end plate, positioned on the second side in the lateral direction of the axial line of the rotor, and a second end disposed further on the second side in the lateral direction of the outer casing than the first end of the first support rod, and connected to an inner surface of the curved plate positioned below the first end of the first support rod. 
     According to the present invention, with provision of the first support rod having the configuration described above, the first support rod functions as a brace (support bar) between the inner surface of the end plate and the inner surface of the curved plate, making it possible to suppress deformation of the outer casing (specifically, the end plate and the lower portion of the curved plate) in which the interior is in a vacuum state. 
     However, in a state in which the bottom plate of the outer casing is fixed to the turbine frame, a fixed portion of the bottom plate of the outer casing and the turbine frame is a constraint point. Then, moments centered on the constraint point are generated in the outer casing in this state. 
     Specifically, a moment is generated in a direction from bottom to top on the curved plate side, a moment is generated in a direction from top to bottom on the exhaust port side, and a moment is generated in a direction from the second end in the lateral direction toward the first end in the lateral direction on the ceiling plate side. 
     With provision of the first support rod having the configuration described above, when the end plate is deformed recessed due to the pressure on the outer side of the outer casing being higher than the pressure inside the outer casing, a force resulting from the deformation of the end plate can be transmitted to the lower portion of the curved plate connected to the second end of the first support rod via the first end of the first support rod. 
     At this time, the force transmitted to the lower end of the curved plate includes a lateral component that acts in a direction from the first side in the lateral direction toward the second side in the lateral direction, and a downward component that acts in a direction that pushes the curved plate downward. 
     Thus, with the downward component of the force transmitted to the lower portion of the curved plate, it is possible to suppress deformation in which the lower portion of the curved plate becomes recessed, and offset a portion of the moment in the direction from bottom to top generated on the curved plate side. 
     Further, a force generated when the steam inside the outer casing is discharged via the exhaust port (specifically, the force that attempts to move the outer casing and the inner casing in a direction from the second side in the lateral direction toward the first side in the lateral direction of the outer casing) can be weakened by the lateral component of the force transmitted to the lower portion of the curved plate. 
     That is, with provision of the first support rod having the configuration described above, deformation of the outer casing is suppressed, making it possible to suppress displacement of the outer casing and the inner casing in the lateral direction toward the exhaust port. 
     Further, the steam turbine system according to an aspect of the present invention described above may further include a second support rod provided inside the outer casing, and extending in one direction. The outer casing may further include a reinforcement rib protruding upward from the bottom plate and including an opposing surface facing the inner surface of the end plate. The second support rod may include a first end connected to a surface, of an inner surface of a lower half of the end plate, on the first side in the lateral direction of the axial line, and a second end connected to the opposing surface of the reinforcement rib positioned further on the second side in the lateral direction of the outer casing than the first end of the second support rod, and above the first end of the second support rod. 
     With provision of the second support rod having the configuration described above, the second support rod functions as a brace between an inner surface of the lower half of the end plate and the opposing surface of the reinforcement rib, making it possible to suppress deformation of the outer casing (specifically, the end plate) in which the interior is in a vacuum state. 
     Further, with provision of the second support rod having the configuration described above, when the end plate is deformed recessed due to the pressure on the outer side of the outer casing being higher than the pressure inside the outer casing, a force resulting from the deformation of the end plate can be transmitted to the reinforcement rib connected to the second end of the second support rod via the first end of the second support rod. 
     At this time, the force transmitted to the reinforcement rib includes a lateral component that acts in a direction from the first side in the lateral direction toward the second side in the lateral direction, and an upward component that acts in a direction that pushes the reinforcement rib upward. 
     Thus, it is possible to reduce the moment in the direction from the top to the bottom that occurs on the exhaust port side by the upward component of the force transmitted to the reinforcement rib. 
     Further, a force generated when the steam inside the outer casing is discharged via the exhaust port (specifically, the force that attempts to move the outer casing and the inner casing in a direction from the second side in the lateral direction toward the first side in the lateral direction of the outer casing) can be weakened by the lateral component of the force transmitted to the reinforcement rib. 
     That is, with provision of the second support rod having the configuration described above, deformation of the outer casing is suppressed, making it possible to suppress displacement of the outer casing and the inner casing in the lateral direction toward the exhaust port. 
     Further, in the steam turbine system according to an aspect of the present invention described above, the second support rod may be inclined more gently than an inclination of the first support rod when viewed in the axial line direction. 
     Thus, by making the inclination of the second support rod including the first end connected to the inner surface of the end plate more gentle than the inclination of the first support rod including the first end connected to the inner surface of the lower half of the curved plate, it is possible to efficiently reduce the moments generated on the curved plate side and the exhaust port side. 
     Further, the steam turbine system according to an aspect of the present invention described above may further include a third support rod provided inside the outer casing, extending in one direction, and including a first end connected to a surface, of an inner surface of an upper half of the end plate, on the first side in the lateral direction of the axial line of the rotor, and a second end connected to an inner surface of the ceiling plate disposed further on the second side in the lateral direction of the outer casing than the first end. 
     Thus, with provision of the third support rod having the configuration described above, the third support rod functions as a brace (support rod) between the inner surface of the end plate and the inner surface of the ceiling plate, making it possible to suppress deformation of the outer casing (specifically, the end plate and the ceiling plate) in which the interior is in a vacuum state. 
     Further, with provision of the third support rod having the configuration described above, when deformation occurs in which the end plate becomes recessed due to the pressure on the outer side of the outer casing being higher than the pressure inside the outer casing, a force resulting from the deformation of the end plate can be transmitted to the ceiling plate connected to the second end of the third support rod via the first end of the third support rod. 
     At this time, because the second end of the third support rod is disposed further on the second side in the lateral direction of the outer casing than the first end of the third support rod, the force transmitted to the ceiling plate includes a lateral component that acts in a direction from the first side in the lateral direction toward the second side in the lateral direction of the outer casing, and an upward component that acts in a direction that pushes the curved plate upward. 
     Thus, with the upward component of the force transmitted to the ceiling plate, it is possible to suppress deformation in which the ceiling plate becomes recessed due to the pressure on the outer side of the outer casing. 
     Further, a force generated when the steam inside the outer casing is discharged via the exhaust port (specifically, the force that attempts to move the outer casing and the inner casing in a direction from the second side in the lateral direction toward the first side in the lateral direction of the outer casing) can be weakened by the lateral component of the force transmitted to the ceiling plate. 
     That is, with provision of the third support rod having the configuration described above, deformation of the outer casing is suppressed, making it possible to suppress displacement of the outer casing and the inner casing in the lateral direction toward the exhaust port. 
     Further, the steam turbine system according to an aspect of the present invention described above may further include a fourth support rod provided inside the outer casing, extending in one direction, and including a first end connected to a surface, of an inner surface of an upper half of the end plate, on the second side in the lateral direction of the axial line, and a second end connected to an inner surface of a lower half of the curved plate such that the fourth support rod is parallel with the vertical direction of the outer casing when viewed in the axial line direction. 
     Thus, with provision of the fourth support rod having the configuration described above, the fourth support rod functions as a brace between the inner surface of the end plate and the inner surface of the curved plate, making it possible to suppress deformation of the outer casing (specifically, the end plate and the curved plate) in which the interior is in a vacuum state. 
     Further, with provision of the fourth support rod having the configuration described above, when deformation occurs in which the end plate becomes recessed due to the pressure on the outer side of the outer casing being higher than the pressure inside the outer casing, a force resulting from the deformation of the end plate can be transmitted to an upper portion of the curved plate via the fourth support rod. 
     At this time, because the fourth support rod is disposed parallel with the vertical direction of the outer casing when viewed in the axial line direction, the force transmitted to the curved plate includes a lateral component that acts in a direction parallel with the axial line direction, and an upward component that acts in a direction that pushes the curved plate upward. 
     Accordingly, the force transmitted by the fourth support rod to the curved plate does not include a component that acts in the direction from the second side in the lateral direction toward the first side in the lateral direction (a component that moves the outer casing and the inner casing to the exhaust port side). As a result, displacement (displacement in the lateral direction) of the outer casing and the inner casing to the exhaust port side caused by the provision of the fourth support rod can be suppressed. 
     Further, the steam turbine system according to an aspect of the present invention may further include a fifth support rod provided inside the outer casing and extending in one direction. The outer casing may further include a side plate facing the curved plate and connected to an end of the ceiling plate disposed on the first side in the lateral direction, an end of the bottom plate disposed on the first side in the lateral direction, and the end plate. The fifth support rod may include a first end connected to an inner surface of the side plate, and a second end connected to an inner surface of the ceiling plate positioned on the second side in the lateral direction of the first end of the fifth support rod. 
     Thus, with provision of the fifth support rod having the configuration described above, the fifth support rod functions as a brace between the inner surface of the side plate and the inner surface of the ceiling plate, making it possible to suppress deformation of the outer casing (specifically, the side plate and the ceiling plate) in which the interior is in a vacuum state. 
     Further, with provision of the fifth support rod having the configuration described above, when deformation occurs in which the side plate becomes recessed on the curved plate side due to the pressure on the outer side of the outer casing being higher than the pressure inside the outer casing, a force resulting from the deformation of the side plate can be transmitted to the ceiling plate connected to the second end of the fifth support rod via the first end of the fifth support rod. 
     At this time, the force transmitted to the ceiling plate includes a lateral component that acts in a direction from the first side in the lateral direction toward the second side in the lateral direction of the outer casing, and an upward component that acts in a direction that pushes the ceiling plate upward. 
     Thus, with the upward component of the force transmitted to the ceiling plate, it is possible to suppress deformation in which the ceiling plate becomes recessed due to the pressure on the outer side of the outer casing. 
     Further, a force generated when the steam inside the outer casing is discharged via the exhaust port (specifically, the force that attempts to move the outer casing and the inner casing in a direction from the second side in the lateral direction toward the first side in the lateral direction of the outer casing) can be weakened by the lateral component of the force transmitted to the ceiling plate. 
     That is, with provision of the fifth support rod having the configuration described above, deformation of the outer casing is suppressed, making it possible to suppress displacement of the outer casing and the inner casing in the lateral direction toward the exhaust port. 
     Further, in the steam turbine system according to an aspect of the present invention, the outer casing may include a side plate facing the exhaust port in a direction intersecting the axial line, two of the exhaust ports may be provided in the axial line direction, and the side plate may be disposed between the two exhaust ports. 
     Thus, the two end plates may be disposed facing each other in the axial line direction across the inner casing. 
     Further, in the steam turbine system according to an aspect of the present invention, two of the exhaust ports may be provided in the axial line direction, and the side plate may be disposed between the two exhaust ports. 
     Thus, the two exhaust ports may be provided in the axial line direction of the rotor, and the side plate may be disposed between the two exhaust ports. 
     Advantageous Effect of Invention 
     According to the present invention, it is possible to suppress deformation of the outer casing, and suppress displacement of the outer casing and the inner casing in the lateral direction toward the exhaust port. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a diagram illustrating a schematic configuration of a steam turbine system according to a first embodiment of the present invention. 
         FIG. 2  is a side view of a low-pressure steam turbine and a condenser illustrated in  FIG. 1 , and an intermediate shell (not illustrated in  FIG. 1 ), as viewed from A. 
         FIG. 3  is a perspective view illustrating a schematic configuration of the low-pressure steam turbine illustrated in  FIG. 2 . 
         FIG. 4  is a cross-sectional view in the A 1 -A 2  line direction of the low-pressure steam turbine illustrated in  FIG. 3 . 
         FIG. 5  is a perspective view of a cross section in the B 1 -B 2  line direction of the low-pressure steam turbine illustrated in  FIG. 3 . 
         FIG. 6  is a diagram of a structural body illustrated in  FIG. 5  as viewed in an axial line direction. 
         FIG. 7  is a cross-sectional view in the C 1 -C 2  line direction of the low-pressure steam turbine illustrated in  FIG. 3 . 
         FIG. 8  is a perspective view schematically illustrating the low-pressure steam turbine illustrated in  FIG. 2  and an intermediate shell in a separated state. 
         FIG. 9  is a diagram (diagram  1 ) for explaining a first support rod included in the steam turbine system according to a second embodiment of the present invention, and is a cross-sectional perspective view of an outer casing schematically illustrating a state in which the first support rod is provided to a first end plate. 
         FIG. 10  is a diagram (diagram  2 ) for explaining the first support rod included in the steam turbine system according to the second embodiment of the present invention, and is a cross-sectional perspective view of the outer casing schematically illustrating the first support rod provided to a second end plate. 
         FIG. 11  is a diagram illustrating a second support rod included in the steam turbine system according to the second embodiment of the present invention, and is an enlarged view of a lower portion of an exhaust port and a lower portion of a side plate of the outer casing. 
         FIG. 12  is an enlarged perspective view of a region D of the structural body illustrated in  FIG. 11 . 
         FIG. 13  is a diagram schematically illustrating the first and second support rods as viewed in the axial line direction. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Embodiments in which the present invention is applied will be described in detail below with reference to the drawings. 
     First Embodiment 
     A steam turbine system  10  of the first embodiment will be described with reference to  FIG. 1  and  FIG. 2 . In  FIG. 1 , a condenser  23  (on the front side of the paper surface) of a low-pressure steam turbine  16  illustrated in  FIG. 1  is illustrated by a dotted line. Further, in  FIG. 1 , an intermediate shell  21  illustrated in  FIG. 2  and an exhaust port  56  illustrated in  FIG. 3  are not illustrated. In  FIG. 1 , an X direction indicates an axial line direction (direction of an axial line Ax) of a turbine rotor  18  (rotor), and a Z direction indicates a vertical direction. 
     In  FIG. 2 , a Y direction indicates a direction orthogonal to the X direction and the Z direction (a direction orthogonal to the axial line direction). In  FIG. 2 , common numerals are assigned to similar components to the structural bodies illustrated in  FIG. 1 . 
     The steam turbine system  10  of the first embodiment includes a steam generator  11 , a steam supply line  12 , a diverging line  12 A, a high-pressure steam turbine  13 , and a moisture separation heater  14 , lines  15 A,  15 B, the low-pressure steam turbine  16 , the turbine rotor  18 , a generator  19 , the intermediate shell  21 , an expandable member  22 , the condenser  23 , and a turbine frame  25 . 
     The steam generator  11  is connected to a first end of the steam supply line  12 . The steam generator  11  generates high-pressure steam. The steam generator  11  supplies the high-pressure steam to the high-pressure steam turbine  13  via the steam supply line  12 , and the moisture separation heater  14 . 
     The steam supply line  12  is connected to the high-pressure steam turbine  13  at a second end. The steam supply line  12  supplies the high-pressure steam generated by the steam generator  11  to the high-pressure steam turbine  13 . 
     The diverging line  12 A diverges from the steam supply line  12 . A leading end of the diverging line  12 A is connected to a steam introduction port  31 A of the low-pressure steam turbine  16 . 
     The high-pressure steam turbine  13  is fixed on the turbine frame  25 . The high-pressure steam turbine  13  houses a portion of the turbine rotor  18  extending in the X direction. 
     The moisture separation heater  14  separates and heats the moisture of the steam from the steam generator  11  and the high-pressure steam turbine  13 . 
     The line  15 A includes a first end connected to the high-pressure steam turbine  13 , and a second end connected to the moisture separation heater  14 . The line  15 A supplies the moisture of the steam from the high-pressure steam turbine  13  to the moisture separation heater  14 . 
     The line  15 B includes a first end connected to the moisture separation heater  14 , and a second end connected to the steam introduction port  31 A of the low-pressure steam turbine  16 . The line  15 B supplies the heated steam to the steam introduction port  31 A of the low-pressure steam turbine  16 . 
     The low-pressure steam turbine  16  will be described with reference to  FIG. 1  to  FIG. 7 . For the structural bodies illustrated in  FIG. 1  to  FIG. 7 , common reference signs are assigned to similar components. In  FIG. 3 , the turbine rotor  18  (refer to  FIG. 1 ) included in the low-pressure steam turbine  16  is not illustrated. In  FIG. 4 , a first support rod  41 , a second support rod  42 , and a third support rod  43  illustrated in  FIG. 5  to  FIG. 7  are not illustrated. In FIG.  4 , for convenience of explanation, the line  15 B that is not a constituent component of the low-pressure steam turbine  16  is illustrated. 
     In  FIGS. 4, 6, and 7 , Ax denotes an axial line of the turbine rotor  18  extending in the X direction illustrated in  FIG. 1  (hereinafter referred to as “axial line Ax”). The axial line Ax is parallel with the X direction. Furthermore, in the following description, the direction in which the axial line Ax extends is referred to as an axial line Ax direction. In  FIG. 5  to  FIG. 7 , for convenience of explanation, an inner casing  31  illustrated in  FIG. 4  is not illustrated. Further,  FIG. 6  and  FIG. 7 , for convenience of explanation, illustrate the turbine rotor  18  not illustrated in  FIG. 3 . 
     Note that, in the first embodiment, an example is given of a case in which the low-pressure steam turbine  16  is a double-flow type (multi-flow type) steam turbine. 
     Further, in the present invention, a “first side in the lateral direction” refers to the side in which the exhaust port  56  is formed in an outer casing  33 . Further, a “second side in the lateral direction” refers to the side in which a curved plate  51  is disposed in the outer casing  33 . 
     The low-pressure steam turbine  16  is disposed between the high-pressure steam turbine  13  and the generator  19  in the X direction. The low-pressure steam turbine  16  is fixed on the turbine frame  25 . 
     The low-pressure steam turbine  16  includes the turbine rotor  18 , the inner casing  31 , the outer casing  33 , the first support rod  41 , the second support rod  42 , and the third support rod  43 . 
     The turbine rotor  18  extends in the X direction and rotates about the axial line Ax. Note that the turbine rotor  18  needs only extend in a horizontal direction parallel with the X direction or the Y direction, and thus an extending direction of the turbine rotor  18  is not limited to the X direction. In the first embodiment, description is given using a case in which the turbine rotor  18  extends in the X direction as an example. 
     The turbine rotor  18  passes through the inner casing  31  and the outer casing  33  in the X direction. A first end side of the turbine rotor  18  disposed on the high-pressure steam turbine  13  side is disposed inside the high-pressure steam turbine  13 , and a second end side disposed on the generator  19  side is disposed inside the generator  19 . 
     Multistage blade rows (not illustrated) disposed in the X direction are respectively provided to a portion of the turbine rotor  18  disposed inside the high-pressure steam turbine  13  and a portion of the turbine rotor  18  disposed inside the low-pressure steam turbine  16 . 
     The turbine rotor  18  is supported in a state rotatable about the axial line by a rotor bearing (not illustrated) disposed on an outer side of the outer casing  33 . 
     The inner casing  31  is fixed to the outer casing  33  in a state of being housed inside the outer casing  33 . The inner casing  31  partitions a space  31 B in the interior thereof. The inner casing  31  includes the steam introduction port  31 A connected to the second end of the line  15 B at an upper end. 
     The steam introduction port  31 A introduces heated steam into the space  31 B via the line  15 B. After the steam introduced into the space  31 B has passed through a gap between the inner casing  31  and the turbine rotor  18  and worked, the steam is discharged in the X direction (specifically, in the direction from the inner casing  31  toward the high-pressure steam turbine  13  and in the direction from the inner casing  31  toward the generator  19 ) inside the outer casing  33 . 
     The outer casing  33  partitions a space  33 A in the interior thereof. The space  33 A is in a vacuum state. A pressure on the outer side of the outer casing  33  is higher than a pressure in the space  33 A in the vacuum state. 
     The outer casing  33  includes a pair of end plates  45 ,  46  (two end plates), a bottom plate  47 , a ceiling plate  48 , the curved plate  51 , a side plate  53 , a reinforcement rib  54 , an opening  55 , and two of the exhaust ports  56 . 
     The pair of end plates  45 ,  46  are disposed facing each other in the X direction across the inner casing  31 . The pair of end plates  45 ,  46  each include an opening  61  for inserting the turbine rotor  18 , and a cone portion  62 . The openings  61  formed in the end plates  45 ,  46  are disposed facing each other in the X direction. 
     The cone portion  62  is a portion having a conical shape recessed toward the space  33 A side. A rotor bearing (not illustrated) that rotatably supports the turbine rotor  18  is disposed adjacent to the cone portion  62 . 
     The bottom plate  47  is disposed below the ceiling plate  48  and extends along a horizontal plane (a plane parallel with the X and Y directions). The bottom plate  47  is connected to lower ends of the pair of end plates  45 ,  46  and a lower end of the side plate  53 . 
     The bottom plate  47  includes an inner surface  47   a  orthogonal to the Z direction. The inner surface  47   a  constitutes a portion of an inner surface of the outer casing  33 . The bottom plate  47  is fixed to the turbine frame  25 . A portion where the bottom plate  47  and the turbine frame  25  are connected serves as a constraint point. 
     The ceiling plate  48  is disposed above the inner casing  31  and extends along a horizontal plane (a plane parallel with the X and Y directions). The ceiling plate  48  is connected to upper ends of the pair of end plates  45 ,  46  and an upper end of the side plate  53 . The ceiling plate  48  includes an inner surface  48   a  (lower surface) that faces the inner surface  47   a  of the bottom plate  47  and is parallel with the inner surface  47   a . The inner surface  48   a  constitutes a portion of the inner surface of the outer casing  33 . 
     The curved plate  51  is connected to an end of the ceiling plate  48  disposed on the second side in the lateral direction, an end of the bottom plate  47  disposed on the second side in the lateral direction, and the pair of end plates  45 ,  46  disposed on the second side in the lateral direction. 
     The curved plate  51  faces the exhaust ports  56  in the Y direction (the direction orthogonal to the axial line Ax of the turbine rotor  18 ). The curved plate  51  includes an inner surface  51   a  that faces the exhaust ports  56 . The inner surface  51   a  is a curved surface. 
     Note that, in the first embodiment, an example is given of a case in which the curved plate  51  and the exhaust ports  56  face each other in a direction orthogonal to the axial line Ax, but the curved plate  51  and the exhaust ports  56  may be disposed facing each other in a direction intersecting the axial line Ax. 
     The curved plate  51  protrudes in a direction separating from the exhaust ports  56 . When viewed in the direction of the axial line Ax, the curved plate  51  can have a semi-circular shape about the axial line Ax of the turbine rotor  18 , for example. 
     Note that, in the first embodiment, a description is given using a case in which the shape of the curved plate  51  is semi-circular about the axial line Ax of the turbine rotor  18  as an example. 
     The side plate  53  is connected to an end of the ceiling plate  48  disposed on the first side in the lateral direction, an end of the bottom plate  47  disposed on the first side in the lateral direction, and the pair of end plates  45 ,  46  disposed on the first side in the lateral direction. 
     The side plate  53  includes an upper portion  53 A, a lower portion  53 B, and an insertion portion  53 C. The upper portion  53 A is disposed above the lower portion  53 B and is connected to the ceiling plate  48 . The upper portion  53 A is disposed on the first side in the lateral direction of the lower portion  53 B. In this way, the insertion portion  53 C is formed below the upper portion  53 A. 
     A support portion  25 B of the turbine frame  25  is inserted into the insertion portion  53 C. With the support portion  25 B inserted into the insertion portion  53 C, a lower surface of the upper portion  53 A and an outer surface of the lower portion  53 B come into contact with the support portion  25 B. 
     A plurality of the reinforcement ribs  54  are provided on the inner surface  47   a  of the bottom plate  47 . The plurality of reinforcement ribs  54  are arranged in the X direction spaced apart from each other. The reinforcement rib  54  is a plate member extending in the Y direction. 
     A plurality of the reinforcement ribs  54  are also provided on the inner surface  47   a  of the bottom plate  47  in correspondence with the exhaust ports  56 . The reinforcement ribs  54  face a portion of the end plates  45 ,  46 . The reinforcement ribs  54  provided to the exhaust ports  56  each include an opposing surface  54   a  that faces the inner surface (inner surface  45   a  or inner surface  46   a ) of one end plate (end plate  45  or end plate  46 ) of the end plates  45 ,  46  disposed adjacent to the reinforcement rib  54 . 
     The opening  55  is provided at a boundary portion between the ceiling plate  48  and the curved plate  51 . The steam introduction port  31 A of the inner casing  31  is disposed in the opening  55 . 
     One of the exhaust ports  56  is provided on each side of the side plate  53  sandwiching the side plate  53  in the X direction. The two exhaust ports  56  protrude to the first side in the lateral direction of the upper portion  53 A of the side plate  53 . The exhaust ports  56  discharge the steam guided from the inner casing  31  into the outer casing  33  to outside the outer casing  33 . 
     The exhaust ports  56  are connected to the intermediate shell  21  via the expandable member  22 . The exhaust ports  56  supply steam to the condenser  23  via the intermediate shell  21 . The shape of the exhaust ports  56  can be, for example, a quadrangle. 
     The first support rod  41  is a support rod extending in one direction, and four first support rods  41  are provided inside the outer casing  33  (refer to  FIGS. 6 and 7 ). Of the first support rods  41 , first ends  41 A of two first support rods  41  are connected to a surface, of the inner surface  45   a  of an upper half of the end plate  45 , on the first side in the lateral direction of the axial line Ax of the turbine rotor  18  (refer to  FIG. 6 ). 
     Second ends  41 B of the two first support rods  41  are connected to the inner surface  48   a  of the ceiling plate  48  disposed further on the second side in the lateral direction of the outer casing  33  than the first ends  41 A. The two first support rods  41  are arranged spaced apart in the Y direction. 
     The first ends  41 A of the remaining two first support rods  41  are connected to a surface, of the inner surface  46   a  of an upper half of the end plate  46 , on the first side in the lateral direction of the axial line Ax of the turbine rotor  18  (refer to  FIG. 7 ). The second ends  41 B of these remaining two first support rods  41  are connected to the inner surface  48   a  of the ceiling plate  48  disposed further on the second side in the lateral direction of the outer casing  33  than the first ends  41 A. The remaining two first support rods  41  are arranged spaced apart. 
     With provision of the first support rods  41  having such a configuration, the first support rods  41  function as braces (support rods) between the inner surfaces  45   a ,  46   a  of the end plates  45 ,  46  and the inner surface  48   a  of the ceiling plate  48 , making it possible to suppress deformation of the outer casing  33  (specifically, the end plates  45 ,  46  and the ceiling plate  48 ) in which the interior is in a vacuum state. 
     Further, with provision of the first support rods  41  having the configuration described above, when deformation occurs in which the end plates  45 ,  46  become recessed due to the pressure on the outer side of the outer casing  33  being higher than the pressure inside the outer casing  33 , a force resulting from the deformation of the end plates  45 ,  46  can be transmitted to the ceiling plate  48  connected to the second ends  41 B of the first support rods  41  via the first ends  41 A of the first support rods  41 . 
     At this time, because the second ends  41 B of the first support rods  41  are disposed further on the second side in the lateral direction of the outer casing  33  than the first ends  41 A of the first support rods  41 , the force transmitted to the ceiling plate  48  includes a lateral component (hereinafter referred to as “lateral component S 1 ”) that acts in a direction from the first side in the lateral direction toward the second side in the lateral direction of the outer casing  33 , and an upward component (hereinafter referred to as “upward component U 1 ”) that acts in a direction that pushes the curved plate  51  upward. 
     Thus, with the upward component U 1  of the force transmitted to the ceiling plate  48 , it is possible to suppress deformation in which the ceiling plate  48  becomes recessed due to the pressure on the outer side of the outer casing  33 . 
     Further, a force generated when the steam inside the outer casing  33  is discharged via the exhaust ports  56  (specifically, the force that attempts to move the outer casing  33  and the inner casing  31  in a direction from the second side in the lateral direction toward the first side in the lateral direction of the outer casing  33 ) can be weakened by the lateral component S 1  of the force transmitted to the ceiling plate  48 . 
     That is, with provision of the first support rods  41  having the configuration described above, deformation of the outer casing  33  is suppressed, making it possible to suppress displacement of the outer casing  33  and the inner casing  31  in the lateral direction toward the exhaust ports  56 . 
     Note that, in  FIGS. 5 to 7 , description has been made using an example in which four first support rods  41  are provided inside the outer casing  33 . The number of the first support rods  41  provided inside the outer casing  33 , however, may be one or more, and is not limited to four. That is, the first support rod  41  may be provided on only one end plate of the pair of end plates  45 ,  46 . 
     The second support rod  42  is a support rod that extends in one direction. Two of the second support rods  42  are provided inside the outer casing  33  with both ends connected to the inner surface of the outer casing  33 . 
     A first end  42 A of one of the second support rods  42  is connected to a surface, of the inner surface  45   a  of the upper half of the end plate  45 , on the second side in the lateral direction of the axial line Ax of the turbine rotor  18 . 
     A second end  42 B of one of the second support rods  42  is connected to the inner surface  51   a  of the curved plate  51  positioned above the first end  42 A of the second support rod  42  such that the second support rod  42  is parallel with the Z direction (vertical direction) of the outer casing  33  when viewed in the axial line Ax direction (the state illustrated in  FIG. 6 ). 
     The first end  42 A of other of the second support rods  42  is connected to a surface, of the inner surface  45   a  of the upper half of the end plate  46 , on the second side in the lateral direction of the axial line Ax of the turbine rotor  18 . 
     The second end  42 B of the other second support rod  42  is connected to the inner surface  51   a  of the curved plate  51  positioned above the first end  42 A of the second support rod  42  such that the second support rod  42  is parallel with the Z direction (vertical direction) of the outer casing  33  when viewed in the axial line Ax direction (the state illustrated in  FIG. 7 ). 
     With provision of the second support rods  42  having such a configuration, the second support rods  42  function as braces (support rods) between the inner surfaces  45   a ,  46   a  of the end plates  45 ,  46  and the inner surface  51   a  of the curved plate  51 , making it possible to suppress deformation of the outer casing  33  (specifically, the end plates  45 ,  46  and the curved plate  51 ) in which the interior is in a vacuum state. 
     Further, with provision of the second support rods  42  having the configuration described above, when deformation occurs in which the end plates  45 ,  46  become recessed due to the pressure on the outer side of the outer casing  33  being higher than the pressure inside the outer casing  33 , a force resulting from the deformation of the end plates  45 ,  46  can be transmitted to an upper portion of the curved plate  51  via the second support rods  42 . 
     At this time, because the second support rods  42  are disposed parallel with the Z direction (vertical direction) of the outer casing  33  when viewed in the axial line Ax direction (refer to  FIG. 6  and  FIG. 7 ), the force transmitted to the curved plate  51  includes a lateral component (hereinafter referred to as “lateral component S 2 ”) that acts in a direction parallel with the axial line Ax direction, and an upward component (hereinafter referred to as “upward component U 2 ”) that acts in a direction that pushes the upper portion of the curved plate  51  upward. 
     Accordingly, the force transmitted from the second support rods  42  to the curved plate  51  does not include a component that acts in the direction from the second side in the lateral direction toward the first side in the lateral direction (a component that moves the outer casing  33  and the inner casing  31  to the exhaust port  56  side). As a result, displacement (displacement in the lateral direction) of the outer casing  33  and the inner casing  31  to the exhaust port  56  side caused by the provision of the second support rods  42  can be suppressed. 
     Note that, in  FIGS. 5 to 7 , description has been made using an example in which two second support rods  42  are provided inside the outer casing  33 . The number of the second support rods  42  provided inside the outer casing  33 , however, may be one or more, and is not limited to two. That is, the second support rod  42  may be provided on only one end plate of the pair of end plates  45 ,  46 . 
     The third support rod  43  is a support rod that extends in one direction. Two of the third support rods  43  are provided inside the outer casing  33  with both ends connected to the inner surface of the outer casing  33 . 
     First ends  43 A of the two third support rods  43  are connected to an inner surface  53 Aa of the upper portion  53 A of the side plate  53 . Second ends  43 B of the two third support rods  43  are connected to the inner surface  48   a  of the ceiling plate  48  positioned on the second side in the lateral direction of the first end  43 A of the third support rod  43 . The two third support rods  43  are arranged in the X direction. 
     With provision of the third support rods  43  having the configuration described above, the third support rods  43  function as braces between the inner surface  53 Aa of the upper portion  53 A of the side plate  53  and the inner surface  48   a  of the ceiling plate  48 , making it possible to suppress deformation of the outer casing  33  (specifically, the side plate  53  and the ceiling plate  48 ) in which the interior is in a vacuum state. 
     Further, with provision of the third support rods  43  having the configuration described above, when the upper portion  53 A of the side plate  53  deforms recessed toward the curved plate  51  side due to the pressure on the outer side of the outer casing  33  being higher than the pressure inside the outer casing  33 , a force resulting from the deformation of the upper portion  53 A of the side plate  53  can be transmitted to the ceiling plate  48  connected to the second ends  43 B of the third support rods  43  via the first ends  43 A of the third support rods  43 . 
     At this time, the force transmitted to the ceiling plate  48  includes a lateral component (hereinafter referred to as “lateral component S 3 ”) that acts in a direction from the first side in the lateral direction toward the second side in the lateral direction of the outer casing  33 , and an upward component (hereinafter referred to as “upward component U 3 ”) that acts in a direction that pushes the ceiling plate  48  upward. 
     Thus, with the upward component U 3  of the force transmitted to the ceiling plate  48 , it is possible to suppress deformation in which the ceiling plate  48  becomes recessed due to the pressure on the outer side of the outer casing  33 . 
     Further, a force generated when the steam inside the outer casing  33  is discharged via the exhaust ports  56  (specifically, the force that attempts to move the outer casing  33  and the inner casing  31  in a direction from the second side in the lateral direction toward the first side in the lateral direction of the outer casing  33 ) can be weakened by the lateral component S 3  of the force transmitted to the ceiling plate  48 . 
     That is, with provision of the third support rods  43  having the configuration described above, deformation of the outer casing  33  is suppressed, making it possible to suppress displacement of the outer casing  33  and the inner casing  31  in the lateral direction toward the exhaust port  56 . 
     Note that, in  FIGS. 5 to 7 , description has been made using an example in which two third support rods  43  are provided inside the outer casing  33 . The number of the third support rods  43  provided inside the outer casing  33 , however, may be one or more, and is not limited to two. 
     As the first to third support rods  41  to  43  described above, for example, a rod made of a metal (carbon steel, for example) can be used. Further, as a method for connecting both ends (the first ends  41 A to  43 A and the second ends  41 B to  43 B) of the first to third support rods  41  to  43  to the inner surface of the outer casing  33 , welding can be used, for example. Note that, instead of welding, a rod with a flange may be fixed by bolts. 
     Next, with reference to  FIG. 1 , description is made of the generator  19 . The generator  19  is fixed on the turbine frame  25 . The generator  19  houses a portion of the turbine rotor  18 . The generator  19  generates power by a rotational energy of the turbine rotor  18 . 
     Next, the intermediate shell  21  will be described with reference to  FIG. 2  and  FIG. 8 . In  FIG. 8 , common reference signs are assigned to similar components to the structural bodies illustrated in  FIG. 2 . Further, in  FIG. 8 , the expandable member  22  illustrated in  FIG. 2  is not illustrated. 
     The intermediate shell  21  is provided between the low-pressure steam turbine  16  and the condenser  23 . The intermediate shell  21  is a member extending in the Y direction. The intermediate shell  21  includes an inflow port  21 A, an outflow port  21 B, and a flow channel  21 C. 
     Two of the inflow ports  21 A are provided on the side facing the low-pressure steam turbine  16 . The two inflow ports  21 A are arranged in the X direction. The two inflow ports  21 A each face one exhaust port  56  in the Y direction. The inflow port  21 A is connected to the exhaust port  56  of the outer casing  33  via the expandable member  22  having a frame shape. The steam guided from the inner casing  31  into the outer casing  33  is discharged into the inflow port  21 A. 
     The outflow port  21 B is provided on the side facing the condenser  23 . The outflow port  21 B is in communication with the inflow port  21 A via the flow channel  21 C. The outflow port  21 B is connected with the condenser  23 . Steam that has passed through the outflow port  21 B is supplied into the condenser  23 . 
     The flow channel  21 C is disposed inside the intermediate shell  21 . The flow channel  21 C connects the inflow port  21 A and the outflow port  21 B, and is a channel for allowing the steam to flow therethrough. 
     The condenser  23  is disposed on the first side in the lateral direction of the outer casing  33  of the low-pressure steam turbine  16 . The condenser  23  is mounted on a support surface  1 . 
     The condenser  23  draws heat from the steam supplied from the low-pressure steam turbine  16  via the intermediate shell  21 , thereby liquefying the steam and generating water. The water produced by the condenser  23  is returned to the steam generator  11  and reused. 
     Note that, in the first embodiment, a case has been described in which the condenser  23  is disposed on the first side in the lateral direction of the outer casing  33  of the low-pressure steam turbine  16 , but the condenser  23  may be disposed on both sides in the lateral direction of the outer casing  33 . 
     Next, the turbine frame  25  will be described with reference to  FIGS. 1 to 3 . The turbine frame  25  is fixed on the support surface  1  (on a floor surface of a building, for example). 
     The turbine frame  25  supports the high-pressure steam turbine  13 , the low-pressure steam turbine  16 , and the generator  19 , and regulates the positions thereof. A recess  25 A for housing a portion of a lower portion of the outer casing  33  is formed in a central portion of the turbine frame  25 . The recess  25 A includes a bottom surface  25 Aa that faces the bottom plate  47  of the outer casing  33 . 
     The turbine frame  25  includes the support portion  25 B that extends upward from the bottom surface  25 Aa and is inserted into the insertion portion  53 C of the outer casing  33 . The support portion  25 B functions to support the outer casing  33  housed in the recess  25 A. 
     Examples of a material of the turbine frame  25  include concrete and reinforced concrete. Further, the turbine frame  25  may be at least partially made of steel. 
     According to the steam turbine system  10  of the first embodiment, the first support rods  41  described above are provided, making it possible to cause the first support rods  41  to function as braces between the inner surfaces  45   a ,  46   a  of the end plates  45 ,  46  and the inner surface  48   a  of the ceiling plate  48 . 
     As a result, deformation of the outer casing  33  (specifically, the end plates  45 ,  46  and the ceiling plate  48 ) in which the interior is in a vacuum state can be suppressed. 
     Further, with provision of the first support rods  41  having the configuration described above, when deformation occurs in which the end plates  45 ,  46  become recessed due to the pressure on the outer side of the outer casing  33  being higher than the pressure inside the outer casing  33 , a force resulting from the deformation of the end plates  45 ,  46  can be transmitted to the ceiling plate  48  connected to the second ends  41 B of the first support rods  41  via the first ends  41 A of the first support rods  41 . 
     At this time, because the second ends  41 B of the first support rods  41  are disposed on the second side in the lateral direction of the outer casing  33  than the first ends  41 A of the first support rods  41 , the force transmitted to the ceiling plate  48  includes the lateral component S 1  that acts in a direction from the first side in the lateral direction toward the second side in the lateral direction of the outer casing  33 , and the upward component U 1  that acts in a direction that pushes the curved plate  51  upward. 
     Thus, with the upward component U 1  of the force transmitted to the ceiling plate  48 , it is possible to suppress deformation in which the ceiling plate  48  becomes recessed due to the pressure on the outer side of the outer casing  33 . 
     Further, a force generated when the steam inside the outer casing  33  is discharged via the exhaust ports  56  (specifically, the force that attempts to move the outer casing  33  and the inner casing  31  in a direction from the second side in the lateral direction toward the first side in the lateral direction of the outer casing  33 ) can be weakened by the lateral component S 1  of the force transmitted to the ceiling plate  48 . 
     That is, according to the steam turbine system  10  of the first embodiment, with provision of the first support rods  41  having the configuration described above, deformation of the outer casing  33  is suppressed, making it possible to suppress displacement of the outer casing  33  and the inner casing  31  in the lateral direction toward the exhaust ports  56 . 
     Note that, in the first embodiment, an example has been given of a case in which the first to third support rods  41  to  43  are provided as support rods connected to the inner surface of the outer casing  33 , but the second and third support rods  42 ,  43  need only be provided as necessary, and are not required. 
     Further, inside the outer casing  33 , the first support rods  41  and the second support rods  42  may be disposed in combination, or the first support rods  41  and the third support rods  43  may be disposed in combination. 
     Further, a plurality of ribs may be provided on the outer surface of the outer casing  33  from the perspective of reinforcing the outer casing  33 . 
     In this case, preferably the first ends  41 A,  42 A of the first and second support rods  41 ,  42  are connected to the inner surfaces  45   a ,  46   a  of the end plates  45 ,  46  corresponding to the intersection of the ribs. 
     Second Embodiment 
     A steam turbine system  70  of a second embodiment will be described with reference to  FIG. 9  to  FIG. 13 .  FIG. 9  to  FIG. 11  illustrate only some of the constituent components included in the steam turbine system  70 . In  FIG. 9  to  FIG. 13 , common reference signs are assigned to similar components to the structural bodies illustrated in  FIG. 1  to  FIG. 8  previously described. Further, in  FIG. 9  to  FIG. 13 , the same reference signs are used for the constituent components that are the same. 
     The steam turbine system  70  of the second embodiment has the same configuration as the steam turbine system  10  except that the steam turbine system  70  includes first and second support rods  71 ,  72  instead of the first to third support rods  41  to  43  included in the steam turbine system  10  of the first embodiment. 
     The first support rod  71  extends in one direction, and four first support rods  71  are provided inside the outer casing  33 . First ends  71 A of the two first support rods  71  are connected to a surface, of the inner surface  45   a  of a lower half of the end plate  45 , on the second side in the lateral direction of the axial line Ax of the turbine rotor  18  (refer to  FIG. 9 ). 
     Second ends  71 B of these two first support rods  71  are disposed further on the second side in the lateral direction of the outer casing  33  than the first ends  71 A of the first support rods  71 , and connected to the inner surface  51   a  of the curved plate  51  positioned below the first ends  71 A of the first support rods  71 . 
     The first ends  71 A of the remaining two first support rods  71  are connected to a surface, of the inner surface  46   a  of a lower half of the end plate  46 , on the second side in the lateral direction of the axial line Ax of the turbine rotor  18  (refer to  FIG. 10 ). 
     The second ends  71 B of these remaining two first support rods  71  are connected to the inner surface  51   a  of the curved plate  51  disposed further on the second side in the lateral direction of the outer casing  33  than the first ends  71 A of the first support rods  71 , and positioned below the first ends  71 A of the first support rods  71  (refer to  FIG. 10 ). 
     However, in a state in which the bottom plate  47  of the outer casing  33  is fixed to the turbine frame  25  illustrated in  FIG. 1 , a fixed portion of the bottom plate  47  and the turbine frame  25  is a constraint point. Then, moments centered on the constraint point are generated in the outer casing  33  in this state. 
     Specifically, a moment is generated in a direction from bottom to top on the curved plate  51  side, a moment is generated in a direction from top to bottom on the exhaust port  56  side, and a moment is generated in a direction from the second end in the lateral direction toward the first end in the lateral direction on the ceiling plate  48  side. 
     With provision of the first support rods  71  having the configuration described above, when the end plates  45 ,  46  are deformed recessed due to the pressure on the outer side of the outer casing  33  being higher than the pressure inside the outer casing  33 , a force resulting from the deformation of the end plates  45 ,  46  can be transmitted to the lower portion of the curved plate  51  connected to the second ends  71 B of the first support rods  71  via the first ends  71 A of the first support rods  71 . 
     At this time, the force transmitted to the lower end of the curved plate  51  includes a lateral component (hereinafter referred to as “lateral component S 4 ”) that acts in a direction from the first side in the lateral direction toward the second side in the lateral direction, and a downward component (hereinafter referred to as “downward component D 1 ”) that acts in a direction that pushes the curved plate  51  downward. 
     Thus, with the downward component D 1  of the force transmitted to the lower portion of the curved plate  51 , it is possible to suppress deformation in which the lower portion of the curved plate  51  becomes recessed, and offset a portion of the moment in the direction from bottom to top generated on the curved plate  51  side. 
     Further, a force generated when the steam inside the outer casing  33  is discharged via the exhaust ports  56  (specifically, the force that attempts to move the outer casing  33  and the inner casing  31  (refer to  FIG. 4 ) in a direction from the second side in the lateral direction toward the first side in the lateral direction of the outer casing  33 ) can be weakened by the lateral component S 4  of the force transmitted to the lower portion of the curved plate  51 . 
     That is, with provision of the first support rods  71  having the configuration described above, deformation of the outer casing  33  is suppressed, making it possible to suppress displacement of the outer casing  33  and the inner casing  31  in the lateral direction toward the exhaust ports  56 . 
     Note that, in the second embodiment, description has been made using an example in which four first support rods  71  are provided inside the outer casing  33 . The number of the first support rods  71  provided inside the outer casing  33 , however, may be one or more, and is not limited to four. That is, the first support rod  71  may be provided on only one end plate of the pair of end plates  45 ,  46 . 
     The second support rod  72  extends in one direction, and two second support rods  72  are provided inside the outer casing  33 . A first end  72 A of one of the second support rods  72  is connected to a surface, of the inner surface  45   a  of the lower half of the end plate  45 , on the first side in the lateral direction of the axial line Ax of the turbine rotor  18 . 
     A second end  72 B of one of the second support rods  72  is connected to the opposing surface  54   a  of the reinforcement rib  54  further on the second side in the lateral direction of the outer casing  33  than the first ends  72 A of the second support rods  72 , and positioned above the first ends  72 A of the second support rods  72 . 
     The first end  72 A of other of the second support rods  72  is connected to a surface, of the inner surface  46   a  of the lower half of the end plate  46 , on the first side in the lateral direction of the axial line Ax of the turbine rotor  18 . 
     The second end  72 B of the other second support rods  72  is connected to the opposing surface  54   a  of the reinforcement rib  54  further on the second side in the lateral direction of the outer casing  33  than the first ends  72 A of the second support rods  72 , and positioned above the first ends  72 A of the second support rods  72 . 
     Thus, with provision of the second support rods  72  having the configuration described above, the second support rods  72  function as braces between the inner surfaces  45   a ,  46   a  of the lower half of the end plates  45 ,  46  and the opposing surface  54   a  of the reinforcement rib  54 , making it possible to suppress deformation of the outer casing  33  (specifically, the end plates  45 ,  46 ) in which the interior is in a vacuum state. 
     Further, with provision of the second support rods  72  having the configuration described above, when the end plates  45 ,  46  are deformed recessed due to the pressure on the outer side of the outer casing  33  being higher than the pressure inside the outer casing  33 , a force resulting from the deformation of the end plates  45 ,  46  can be transmitted to the reinforcement rib  54  connected to the second ends  72 B of the second support rods  72  via the first ends  72 A of the second support rods  72 . 
     At this time, the force transmitted to the reinforcement rib  54  includes a lateral component that acts in a direction from the first side in the lateral direction toward the second side in the lateral direction, and an upward component that acts in a direction that pushes the reinforcement rib  54  upward. 
     Thus, it is possible to reduce the moment in the direction from the top to the bottom that occurs on the exhaust port  56  side by the upward component of the force transmitted to the reinforcement rib  54 . 
     Further, a force generated when the steam inside the outer casing  33  is discharged via the exhaust ports  56  (specifically, the force that attempts to move the outer casing  33  and the inner casing  31  (refer to  FIG. 4 ) in a direction from the second side in the lateral direction toward the first side in the lateral direction of the outer casing  33 ) can be weakened by the lateral component of the force transmitted to the reinforcement rib  54 . 
     That is, with provision of the second support rods  72  having the configuration described above, deformation of the outer casing  33  is suppressed, making it possible to suppress displacement of the outer casing  33  and the inner casing  31  in the lateral direction toward the exhaust ports  56 . 
     Note that, in the second embodiment, description has been made using an example in which two second support rods  72  are provided inside the outer casing  33 . The number of the second support rods  72  provided inside the outer casing  33 , however, may be one or more, and is not limited to two. That is, the second support rod  72  may be provided on only one end plate of the pair of end plates  45 ,  46 . 
     Examples of the first and second support rods  71 ,  72  described above include a rod made of a metal such as carbon steel. Further, to connect both ends (the first ends  71 A,  72 A and the second ends  71 B,  72 B) of the first and second support rods  71 ,  72  and the inner surface of the outer casing  33 , welding can be used, for example. Note that, instead of welding, a rod with a flange may be fixed by bolts. 
     Next, inclinations of the first and second support rods  71 ,  72  will be described with reference to  FIG. 13 . 
       FIG. 13  is a diagram of the first and second support rods  71 ,  72  disposed on the end plate  45  side as viewed in the axial line Ax direction. In  FIG. 13 , common reference signs are assigned to similar components to the structural bodies illustrated in  FIGS. 9 and 11 . 
     As illustrated in  FIG. 13 , the second support rod  72  may be inclined more gently than an inclination of the first support rod  71  when viewed in the axial line Ax direction. Thus, by making the inclinations of the second support rods  72  connected at the first ends  72 A to the inner surfaces  45   a ,  46   a  of the end plates  45 ,  46  more gentle than the inclination of the first support rods  71  connected at the first ends  71 A to the inner surface  51   a  of the lower half of the curved plate  51 , it is possible to efficiently reduce the moments generated on the curved plate side and the exhaust port side. 
     Thus, according to the steam turbine system  70  of the second embodiment, by providing the first support rods  71  described above, it is possible to suppress deformation in which the lower portion of the curved plate  51  becomes recessed, and offset a portion of the moment in the direction from bottom to top generated on the curved plate  51  side by the downward component of the force transmitted to the lower portion of the curved plate  51  via the first support rods  71 . 
     Further, a force generated when the steam inside the outer casing  33  is discharged via the exhaust ports  56  (specifically, the force that attempts to move the outer casing  33  and the inner casing  31  (refer to  FIG. 4 ) in a direction from the second side in the lateral direction toward the first side in the lateral direction of the outer casing  33 ) can be weakened by the lateral component of the force transmitted to the lower portion of the curved plate  51 . 
     That is, with provision of the first support rods  71  having the configuration described above, deformation of the outer casing  33  is suppressed, making it possible to suppress displacement of the outer casing  33  and the inner casing  31  in the lateral direction toward the exhaust ports  56 . 
     Note that, in the second embodiment, description has been made using an example in which the first and the second support rods  71 ,  72  are provided inside the outer casing  33 . The second support rod  72 , however, is not required, and may be provided as necessary. 
     Further, a plurality of ribs may be provided on the outer surface of the outer casing  33  from the perspective of reinforcing the outer casing  33 . 
     In this case, preferably the first ends  71 A of the first support rods  71  and the first ends  72 A of the second support rods  72  are connected to the inner surfaces of the end plates  45 ,  46  corresponding to the intersection of the ribs. 
     Further, the first support rod  41  described in the first embodiment may be applied as the third support rod, and the second support rod  42  described in the first embodiment may be applied as a fourth support rod to the steam turbine system  70  of the second embodiment. Furthermore, the third support rod  43  described in the first embodiment may be applied as a fifth support rod to the steam turbine system  70  of the second embodiment. 
     In this way, by applying at least one of the third support rods  41  to  43  described in the first embodiment to the steam turbine system  70  of the second embodiment, the same effects as those described in the first embodiment can be obtained. 
     Although preferable embodiments of the present invention have been described above in detail, the present invention is not limited to those specific embodiments. Various modifications and changes can be made to the embodiments without departing from the scope and spirit of the present invention described in the claims. 
     For example, the first support rod  71  described in the second embodiment may be applied as the fourth support rod to the steam turbine system  10  of the first embodiment. In this case, the same effects as those of the first support rod  71  described in the second embodiment can be obtained. 
     Further, the second support rod  72  described in the second embodiment may be applied as the fifth support rod to the steam turbine system  10  of the first embodiment. In this case, the same effects as those of the second support rod  72  described in the second embodiment can be obtained. 
     INDUSTRIAL APPLICABILITY 
     The present invention is applicable to a steam turbine system. 
     REFERENCE SIGNS LIST 
     
         
           1  Support surface 
           10 ,  70  Steam turbine system 
           11  Steam generator 
           12  Steam supply line 
           12 A Diverging line 
           13  High-pressure steam turbine 
           14  Moisture separation heater 
           15 A,  15 B Line 
           16  Low-pressure steam turbine 
           18  Turbine rotor 
           19  Generator 
           21  Intermediate shell 
           21 A Inflow port 
           21 B Outflow port 
           21 C Flow channel 
           22  Expandable member 
           23  Condenser 
           25  Turbine frame 
           25 A Recess 
           25 Aa Bottom surface 
           25 B Support portion 
           31  Inner casing 
           31 A Steam introduction port 
           31 B,  33 A Space 
           33  Outer casing 
           41 ,  71  First support rod 
           41 A,  42 A,  43 A,  71 A,  72 A First end 
           41 B,  42 B,  43 B,  71 B,  72 B Second end 
           42 ,  72  Second support rod 
           43  Third support rod 
           45 ,  46  End plate 
           45   a ,  46   a ,  47   a ,  48   a ,  51   a ,  53 Aa Inner surface 
           47  Bottom plate 
           48  Ceiling plate 
           51  Curved plate 
           53  Side plate 
           53 A Upper portion 
           53 B Lower portion 
           53 C Insertion portion 
           54  Reinforcement rib 
           54   a  Opposing surface 
           55 ,  61  Opening 
           56  Exhaust port 
           62  Cone portion 
         Ax Axial line