Patent Publication Number: US-11022000-B2

Title: Steam turbine assembling method, steam turbine, and upper half assembly

Description:
TECHNICAL FIELD 
     The present invention relates to a steam turbine assembling method, a steam turbine, and an upper half assembly. 
     BACKGROUND OF THE INVENTION 
     A steam turbine includes: a rotor which rotates about an axis; and a casing which covers the rotor. The rotor includes a plurality of rotor blades which are disposed around a rotor shaft extending in an axial direction about the axis. A partition plate having a plurality of stator blades (nozzles) which are disposed around the rotor on an upstream side of the rotor blade is fixed to the casing. In the steam turbine, from the viewpoint of assembly or the like thereof, a cylindrical casing and an annular partition plate are divided into a plurality in a circumferential direction. 
     For example, Patent Document 1 discloses a steam turbine in which each of a partition plate and a casing is divided into an upper half and a lower half. In the steam turbine, a structure for regulating a vertical movement is provided in each of an upper half portion and a lower half portion. Specifically, a structure is provided, in which a partition plate support piece provided so as to protrude from an inner surface of the casing is inserted into a support groove formed on an outer peripheral surface of the support piece. 
     Meanwhile, in order to insert the partition plate support piece into the support groove, it is necessary to lift the partition plate so as to adjust the partition plate each time positioning adjustment between the casing and the partition plate is performed. Accordingly, as a structure configured to decrease the amount of adjustment needed, Patent Document 1 discloses a structure in which a slit-attached screw is screwed into a screw hole provided in a tangential direction at a boundary between the casing and the partition plate. In this structure, the position of the casing and the partition plate is completely fixed by the screw. 
     DOCUMENTS OF RELATED ART 
     Patent Documents 
     Patent Document 1: Japanese Unexamined Utility Model Application, First Publication No. H2-87905 
     SUMMARY OF THE INVENTION 
     Problems to be Solved by the Invention 
     However, in this way, if the position of the casing and the partition plate is completely fixed, it is difficult to absorb slight deviation generated when an upper half assembly which is the upper half portion and a lower half assembly which is the lower half portion are assembled together. As a result, there is a possibility that a gap is generated between the upper half assembly and the lower half assembly. Accordingly, it is desirable to suppress the occurrence of a gap between the upper half assembly and the lower half assembly while decreasing the amount of adjustment needed in positioning. 
     The present invention provides a steam turbine assembling method, a steam turbine, and an upper half assembly capable of suppressing occurrence of the gap between the upper half assembly and the lower half assembly while decreasing the amount of adjustment needed in positioning. 
     Means to Solve the Problems 
     A steam turbine assembling method according to a first aspect of the present invention includes: an upper half casing preparation step in which an upper half casing is prepared, the upper half casing extending in a circumferential direction of a rotor rotatable about a axis an including upper half casing division surfaces on both ends thereof in the circumferential direction, the upper half casing division surfaces being horizontal surfaces facing downward in a vertical direction; a lower half casing preparation step in which a lower half casing is prepared, the lower half casing extending in the circumferential direction and including lower half casing division surfaces on both ends thereof in the circumferential direction, the lower half casing division surfaces being capable of abutting against the upper half casing division surfaces; an upper half partition plate preparation step in which an upper half partition plate is prepared, the upper half partition plate extending in the circumferential direction to be able to be disposed on an inner peripheral side of the upper half casing and including upper half partition plate division surfaces on both ends thereof in the circumferential direction, the upper half partition plate division surfaces being horizontal surfaces facing downward in the vertical direction; a lower a ion plate preparation step in which a lower half partition plate is prepared, the lower half partition plate extending in the circumferential direction to be able to be disposed on an inner peripheral side of the lower half casing and including lower half partition plate division surfaces on both ends thereof in the circumferential direction, the lower half partition plate division surfaces being capable of abutting against the upper half partition plate division surfaces; an upper half assembling step in which the upper half partition plate is disposed on the inner peripheral side of the upper half casing to form an upper half assembly; a lower half assembling step in which, after disposing the lower half partition plate on the inner peripheral side of the lower half casing, a lower half position defining portion having a lower half abutment surface which is a horizontal surface is fixed to at least one of the lower half casing and the lower half partition plate in a state where the lower half abutment surface abuts against the lower half casing division surface and the lower half partition plate division surface to form a lower half assembly; and a final assembling step in which the upper half casing division surfaces are made to abut against the lower half casing division surfaces so as to install the upper half assembly on the lower half assembly. 
     According to this configuration, after the half partition plate is disposed on the inner peripheral side of the lower half casing, the lower half position defining portion is attached. Accordingly, the positions of the lower half casing division surface and the lower half partition plate division surface can be defined in a state where the lower half casing and the lower half partition plate are assembled together. In addition, the lower half casing division surface and the lower half partition plate division surface come into contact with the lower half abutment surface, and thus, the lower half casing division surface and the lower half partition plate division surface are disposed on the same horizontal surface. In this state, the lower half abutment member is fixed to one of the lower half partition plate and the lower half casing, and thus, the state where the lower half casing division surface and the lower half partition plate division surface are disposed on the same horizontal surface as each other is maintained. Accordingly, it is possible to define the positions of the lower half casing and the lower half partition plate in the vertical direction while decreasing the amount of adjustment needed in positioning of the lower half assembly. 
     In the steam turbine assembling method according to a second aspect of the present invention, the lower half assembling step according to the first aspect may include fixing the lower half position defining portion to the lower half partition plate division surface. 
     In the steam turbine assembling method according to a third aspect of the present invention, the upper half casing preparation step according to the first or second aspect may include preparing the upper half casing having an upper half casing recessed portion recessed upward in the vertical direction on an inner peripheral side of the upper half casing division surface so as to form an upper half casing recess surface facing in a direction including the vertical direction, the upper half partition plate preparation step may include preparing the upper half casing having an upper half partition plate recessed portion which is recessed upward in the vertical direction on an outer peripheral side of the upper half partition plate division surface so as to form an upper half partition plate recess surface facing in the direction including the vertical direction and forms an accommodation space communicating with the upper half casing recessed portion when being disposed on the inner peripheral side of the upper half casing, and the lower half assembling step may include disposing the lower half position defining portion at a position at which the lower half position defining portion is accommodated in the accommodation space when the upper half assembly is installed on the lower half assembly. 
     According to this configuration, when the lower half assembly and the upper half assembly are combined with each other, it is possible to prevent the lower half abutment member from being disposed between the lower half partition plate division surface and the upper half partition plate division surface or at an interference position between the lower half partition plate division surface and the upper half partition plate division surface. Therefore, when the lower half assembly and the upper half assembly are combined with each other, it is possible to prevent the lower half abutment member from becoming an obstacle. 
     A steam turbine according to a fourth aspect of the present invention includes: an upper half casing which extends in a circumferential direction of a rotor rotatable about an axis and includes upper half casing division surfaces, which are horizontal surfaces facing downward in a vertical direction, on both ends thereof in the circumferential direction; a lower half casing which extends in the circumferential direction and includes lower half casing division surfaces capable of abutting against the upper half casing division surfaces on both ends thereof in the circumferential direction; an upper half partition plate which extends in the circumferential direction to be able to be disposed on an inner peripheral side of the upper half casing and includes upper half partition plate division surfaces, which are horizontal surfaces facing downward in the vertical direction, on both ends thereof in the circumferential direction; a lower half partition plate which extends in the circumferential direction to be able to be disposed on an inner peripheral side of the lower half casing and includes lower half partition plate division surfaces on both ends thereof in the circumferential direction, the lower half partition plate division surfaces being capable of abutting against the upper half partition plate division surfaces; and a lower half position defining portion which includes a lower half abutment surface which is a horizontal surface and abuts against the lower half casing division surface and the lower half partition plate division surface and is fixed to at least one of the lower half casing and the lower half partition plate. 
     A lower half assembly according to a fifth aspect of the present invention includes: a lower half casing which extends in a circumferential direction of a rotor rotatable about an axis and includes lower half casing division surfaces capable of abutting against upper half casing division surfaces, which are horizontal surface facing downward in a vertical direction, on both ends thereof in the circumferential direction; a lower half partition plate which extends in the circumferential direction to be able to be disposed on an inner peripheral side of the lower half casing and includes lower half partition plate division surfaces capable of abutting against upper half partition plate division surfaces, which are horizontal surface facing downward in the vertical direction, on both ends thereof in the circumferential direction; and a lower half position defining portion which includes a lower half abutment surface which is a horizontal surface and abuts against the lower half casing division surface and the lower half partition plate division surface and is fixed to at least one of the lower half casing and the lower half partition plate. 
     Effects of the Invention 
     According to the present invention, it is possible to suppress occurrence of a gap between the upper half assembly and the lower half assembly while decreasing the amount of adjustment needed in positioning. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a sectional view of a steam turbine according to an embodiment of the present invention. 
         FIG. 2  is a sectional view taken along line II-II in  FIG. 1 . 
         FIG. 3  is a main portion enlarged view showing an upper half vertical position defining member and a lower half vertical position defining member according to the embodiment of the present invention. 
         FIG. 4  is a main portion enlarged view showing the upper half vertical position defining member according to the embodiment of the present invention in a vertical direction. 
         FIG. 5  is a main portion enlarged view showing an upper half horizontal position defining member according to the embodiment of the present invention. 
         FIG. 6  is a main portion enlarged showing a lower half horizontal position defining member according to the embodiment of the present invention. 
         FIG. 7  is a flowchart of a steam turbine assembling method according to the embodiment of the present invention. 
     
    
    
     EMBODIMENTS FOR CARRYING OUT THE INVENTION 
     Hereinafter, embodiment of a steam turbine of the present invention will be described with reference to the drawings. 
     As shown in  FIGS. 1 and 2 , a steam turbine  1  includes: a rotor  2 ; partition plates  3 ; a casing  4 ; upper half vertical position defining portions (upper half position defining portions)  5 ; lower half vertical position defining portions (lower half position defining portions)  6 ; an upper half horizontal position defining portion  7 ; and a lower half horizontal position defining portion  8 . 
     The rotor  2  can rotate about an axis Ar. The rotor  2  includes: a rotor shaft  21  which extends in an axial direction Da about the axis Ar; and a plurality of rotor blades  22  which are fixed to the rotor shaft  21  to be aligned in a circumferential direction De with respect to the rotor shaft  21 . 
     Moreover, hereinafter, a direction in which the axis Ar extends is referred to as the axial direction Da. A radial direction Dr based on the axis Ar is simply referred to as the radial direction Dr. In the radial direction Dr perpendicular to the axis Ar, an up direction on a paper surface of  FIG. 2  is referred to as a vertical direction Dv. In addition, a right-left direction of  FIG. 2  is referred to as a horizontal direction Dh. Moreover, a direction around the rotor  2  about the axis Ar is referred to as a circumferential direction Dc. 
     The partition plate  3  is disposed on an outer peripheral side of the rotor  2 . The partition plate  3  is formed in an annular shape about the axis Ar. In the annular partition plate  3 , a plurality of stator blades (nozzles)  30  aligned in the circumferential direction Dc are provided on an inner peripheral side of the partition plate  3  at a position on an upstream side of the rotor blade  22  of the rotor  2 . In the steam turbine  1 , a tubular space between an outer peripheral side of the rotor shaft  21  and an inner peripheral side of the annular partition plate  3 , in other words, a space in which the rotor blades  22  and the stator blades  30  are disposed becomes a steam flow path. The annular partition plate  3  includes: an upper half partition plate  31  on an upper side based on the axis Ar of the rotor  2  in the vertical direction Dv; and a lower half partition plate  32  on a lower side based on the axis Ar of the rotor  2  in the vertical direction Dv. The upper half partition plate  31  and the lower half partition plate  32  will be described in detail later. 
     The casing  4  is disposed on the outer peripheral side of the partition plate  3 . The casing  4  is formed in a tubular shape about the axis Ar. The tubular casing  4  includes: an upper half casing  41  on an upper side based on the axis Ar of the rotor  2 ; and a lower half casing  42  on a lower side based on the axis Ar of the rotor  2 . 
     In the present embodiment, as shown in  FIG. 2 , the upper half casing  41  and the upper half partition plate  31  are combined with each other so as to constitute an upper half assembly  11 . The lower half casing  42  and the lower half partition plate  32  are combined with each other so as to constitute a lower half assembly  12 . The upper half assembly  11  is disposed with respect to the lower half assembly  12  such that the rotor  2  is interposed therebetween, and thus, the steam turbine  1  is formed. 
     The upper half casing  41  extends in the circumferential direction Dc. In the upper half casing  41  of the present embodiment, flanges extending in the horizontal direction Dh are formed on both ends thereof in the circumferential direction De. The upper half casing  41  has upper half casing division surfaces  41 X on both ends thereof in the circumferential direction Dc. Each of the upper half casing division surfaces  41 X is one division surface when the casing  4  is divided into upper and lower portions in the vertical direction Dv. Each upper half casing division surface  41 X is a flat surface which spreads in the radial direction Dr and the axial direction Da. That is, the upper half casing division surface  41 X is a horizontal surface facing downward in the vertical direction Dv. The upper half casing  41  of the present embodiment includes: an upper half casing body  410 ; upper half casing first recessed portions (upper half casing recessed portions)  411 ; and an upper half casing second recessed portion  412 . 
     In the upper half casing body  410 , a cross section orthogonal to the axis Ar is formed in a semicircular annular shape about the axis Ar. The upper half casing body  410  is open downward in the vertical direction Dv such that the rotor  2  and the partition plate  3  are fitted into the upper half casing body  410 . 
     The upper half casing first recessed portions  411  are respectively formed symmetrically on the two upper half casing division surfaces  41 X separated from each other in the horizontal direction Dh. Here, the upper half casing first recessed portion  411 , which is positioned on one side in the horizontal direction Dh which is a right side in a paper surface in  FIG. 2 , is described as an example. In addition, the upper half casing first recessed portion  411  positioned on the other side in the horizontal direction Dh, which is not described, has the same shape. 
     As shown in  FIG. 3 , the upper half casing first recessed portion  411  is recessed from the upper half casing division surface  41 X. The upper half casing first recessed portion  411  is recessed upward in the vertical direction Dv on an inner peripheral side of the upper half casing division surface  41 X. The upper half casing first recessed portion  411  is formed at a corner which is formed by an inner peripheral surface of the upper half casing body  410  and the upper half casing, division surface  41 X. As shown in  FIG. 4 , the upper half casing first recessed portion  411  is recessed from the inner peripheral surface of the upper half casing body  410  so as to form a semicircular shape when viewed from the upper half casing division surface  41 X. As shown in  FIG. 3 , the upper half casing first recessed portion  411  includes: an upper half casing first flat surface (upper half casing recess surface)  411   a  facing in a direction including the vertical direction Dv; and an upper half casing first curved surface  411   b  facing the inside in the radial direction Dr. 
     The upper half casing first flat surface  411   a  is a surface which spreads in the radial direction Dr and the axial direction Da toward the upper half casing division surface  41 X side so as to face in the direction including the vertical direction Dv. The upper half casing first flat surface  411   a  of the present embodiment is a horizontal surface facing downward in the vertical direction Dv. Accordingly, the upper half casing first flat surface  411   a  is formed to be parallel to the upper half casing division surface  41 X. A bolt hole is formed in the upper half casing first flat surface  411   a.    
     In addition, the upper half casing first flat surface  411   a  may be a flat surface facing in a direction inclined with respect to the vertical direction Dv as long as it is a surface facing in the direction including the vertical direction Dv. 
     The upper half casing first curved surface  411   b  is connected to the upper half casing division surface  41 X and the upper half casing first flat surface  411   a . The upper half casing first curved surface  411   b  spreads in a direction orthogonal to the upper half casing division surface  41 X and the upper half casing first flat surface  411   a . The upper half casing first curved surface  411   b  is a concave curved surface facing the inside in the radial direction Dr in a cross section orthogonal to the axis Ar. The upper half casing first curved surface  411   b  extends in the vertical direction Dv from the upper half casing division surface  41 X. 
     As shown in  FIG. 2 , the upper half casing second recessed portion  412  is formed on a top portion of the upper half casing body  410  in the vertical direction Dv. As shown in  FIG. 5 , the upper half casing second recessed portion  412  is recessed from the inner peripheral surface of the upper half casing body  410  toward the outside in the radial direction Dr. For example, the upper half casing second recessed portion  412  is recessed to be formed in a circular shape. The upper half casing second recessed portion  412  includes: an upper half easing second flat surface  412   a  facing the inside in the radial direction Dr; and an upper half casing second curved surface  412   b  which connects the inner peripheral surface of the upper half casing body  410  and the upper half casing second flat surface  412   a  to each other. 
     The upper half casing second flat surface  412   a  is a flat surface facing downward in the vertical direction Dv. The upper half casing second flat surface  412   a  is formed in a circular shape when viewed from the inside in the radial direction Dr. The upper half casing second curved surface  412   b  is a concave curved surface which extends in the vertical direction Dv from the inner peripheral surface of the upper half casing body  410 . 
     As shown in  FIG. 2 , the lower half casing  42  extends in the circumferential direction Dc. In the lower half casing  42  of the present embodiment, flanges extending in the horizontal direction Dh are formed on both ends thereof in the circumferential direction Dc. The lower half casing  42  has lower half casing division surfaces  42 X on both ends thereof in the circumferential direction Dc. Each of the lower half casing division surfaces  42 X is the other division surface when the casing  4  is divided into upper and lower portions in the vertical direction Dv. Each lower half casing division surface  42 X is a flat surface which spreads in the radial direction Dr and the axial direction Da. That is, the lower half casing division surface  42 X is a horizontal surface facing upward in the vertical direction Dv. The lower half casing  42  of the present embodiment includes: a lower half casing body  420 ; and a lower half casing first recessed portion  421 . 
     In the lower half casing body  420 , a cross section orthogonal to the axis Ar is formed in a semicircular annular shape about the axis Ar. An inner diameter of the lower half casing body  420  is the same as an inner diameter of the upper half casing body  410 . The lower half casing body  420  is open upward in the vertical direction Dv such that the rotor  2  and the partition plate  3  are fitted into the lower half casing body  420 . 
     The lower half casing first recessed portion  421  is formed on a bottom portion of the upper half casing body  410  in the vertical direction Dv. As shown in  FIG. 6 , the lower half casing first recessed portion  421  is recessed from the inner peripheral surface of the lower half casing body  420  toward the outside in the radial direction Dr. For example, the lower half casing first recessed portion  421  is recessed to be formed in a circular shape. The lower half casing first recessed portion  421  has a shape symmetrical to the upper half casing second recessed portion  412  with a horizontal surface passing through the axis Ar as a boundary. The lower half casing first recessed portion  421  includes: a lower half casing first flat surface  421   a  facing the inside in the radial direction Dr; and a lower half casing first curved surface  421   b  which connects the inner peripheral surface of the lower half casing body  420  and the lower half casing first flat surface  421   a  to each other. 
     The lower half casing first flat surface  421   a  is a flat face facing upward in the vertical direction Dv. The lower half casing first flat surface  421   a  is formed in a circular shape having the same diameter as that of the upper half casing second flat surface  412   a  when viewed from h inside in the radial direction Dr. The lower half casing first curved surface  421   b  is a concave curved surface which extends in the vertical direction Dv from the inner peripheral surface of the upper half casing body  410 . 
     As shown in  FIG. 2 , the upper half partition plate  31  extends in the circumferential direction Dc. The upper half partition plate  31  can be disposed on an inner peripheral side of the upper half casing  41 . The upper half partition plate  31  has upper half partition plate division surfaces  31 X on both ends thereof in the circumferential direction Dc. The upper half partition plate division surface  31 X is one division surface when the partition plate  3  is divided into upper and lower portions in the vertical direction Dv. The upper half partition plate division surface  31 X is a flat surface which spreads in the radial direction Dr and the axial direction Da. That is, the upper half partition plate division surface  31 X is a horizontal surface facing downward in the vertical direction Dv. The upper half partition plate  31  of the present embodiment includes: an upper half partition plate body  310 ; upper half partition plate first recessed portions (upper half partition plate recessed portions)  311 ; and an upper half partition plate second recessed portion  312 . 
     In the upper half partition plate body  310 , a cross section orthogonal to the axis Ar is formed in a semicircular annular shape about the axis Ar. The upper half partition plate body  310  can be accommodated in an opening portion of the upper half casing body  410  in a state where a slight gap is provided on the inner peripheral surface side of the upper half casing body  410 . The upper half partition plate body  310  is formed such that an outer diameter thereof is slightly smaller than the inner diameter of the upper half casing body  410 . The upper half partition plate body  310  is open downward in the vertical direction Dv such that the rotor  2  is fitted into the upper half partition plate body  310 . 
     The upper half partition plate first recessed portions  311  are respectively formed symmetrically on the two upper half partition plate division surfaces  31 X separated from each other in the horizontal direction Dh. Here, the upper half partition plate first recessed portion  311 , which is positioned on one side in the horizontal direction Dh which is the right side in the paper surface in  FIG. 2 , is described as an example. In addition, the upper half partition plate first recessed portion  311  positioned on the other side in the horizontal direction Dh, which is not described, has the same shape. 
     As shown in  FIG. 3 , the upper half partition plate first recessed portion  311  is recessed from the upper half partition plate division surface  31 X. The upper half partition plate first recessed portion  311  is recessed upward in the vertical direction Dv on an inner peripheral side of the upper half partition plate division surface  31 X. The upper half partition plate first recessed portion  311  is formed at a corner which is formed by an outer peripheral surface of the upper half partition plate body  310  and the upper half partition plate division surface  31 X. The upper half partition plate first recessed portion  311  forms an accommodation space S which communicates with the upper half casing first recessed portion  411  when the upper half partition plate  31  is disposed on the inner peripheral side of the upper half casing  41 . Accordingly, the upper half partition plate first recessed portion  311  of the present embodiment is formed such that positions thereof in the circumferential direction Dc and the axial direction Da are the same as those of the upper half casing first recessed portion  411  in a state where the upper half partition plate  31  is disposed on the inner peripheral side of the upper half casing  41 . As shown in  FIG. 4 , the upper half partition plate first recessed portion  311  is formed at a position closer to one side in the axial direction Da with respect to the upper half partition plate body  310 . The upper half partition plate first recessed portion  311  is recessed from the upper half partition plate body  310  to be formed in a semicircular arc shape when viewed from the upper half partition plate division surface  31 X side. As shown in  FIG. 3 , the upper half partition plate first recessed portion  311  includes: an upper half partition plate first flat surface (upper half partition plate recess surface)  311   a  facing in the direction including the vertical direction Dv; and an upper half partition plate first curved surface  311   b  facing the outside in the radial direction Dr. 
     In addition, the upper half partition plate first recessed portion  311  is not limited to being formed at the position closer to the one side in the axial direction Da with respect to the upper half partition plate body  310 . For example, in a case where a thickness of the upper half partition plate body  310  in the axial direction Da is sufficiently secured, the upper half partition plate first recessed portion  311  may be formed at a center position in the axial direction Da with respect to the upper half partition plate body  310 . 
     The upper half partition plate first flat surface  311   a  is a surface which spreads in the radial direction Dr and the axial direction Da toward the upper half partition plate division surface  31 X side so as to face in the direction including the vertical direction Dv. The upper half partition plate first flat surface  311   a  of the present embodiment is a horizontal surface facing downward in the vertical direction Dv. Accordingly, the upper half partition plate first flat surface  311   a  is formed to be parallel to the upper half partition plate division surface  31 X. The upper half partition plate first flat surface  311   a  is formed so as to be positioned on a side closer to the upper half partition plate division surface  31 X than the upper half casing first flat surface  411   a  in a state where the upper half partition plate  31  is disposed on the inner peripheral side of the upper half casing  41  and the upper half partition plate division surface  31 X and the upper half casing division surface  41 X are disposed on the same surface as each other. That is, when the upper half assembly  11  and the lower half assembly  12  are assembled together, the upper half partition plate first flat surface  311   a  is positioned below the upper half casing first flat surface  411   a  in the vertical direction Dv. A bolt hole configured to fix the upper half vertical position defining portion  5  is formed on the upper half partition plate first flat surface  311   a.    
     In addition, the upper half partition plate first flat surface  311   a  may be a flat surface facing in a direction inclined with respect to the vertical direction Dv as long as it is a surface facing in the direction including the vertical direction Dv. 
     The upper half partition plate first curved surface  311   b  is connected to the upper half partition plate division surface  31 X and the upper half partition plate first flat surface  311   a . The upper half partition plate first curved surface  311   b  spreads in a direction orthogonal to the upper half partition plate division surface  31 X and the upper half partition plate first flat surface  311   a . The upper half partition plate  31  casing  4  first curved surface is a concave curved surface facing the outside in the radial direction Dr in a cross section orthogonal to the axis Ar. The upper half partition plate first curved surface  311   b  extends in the vertical direction Dv from the upper half partition plate division surface  31 X. A length of the upper half partition plate first curved surface  311   b  in the vertical direction Dv s shorter than a length of the upper half casing first curved surface  411   b  in the vertical direction Dv. 
     As shown in  FIG. 2 , the upper half partition plate second recessed portion  312  is formed on a top portion of the upper half partition plate body  310  in the vertical direction Dv. As shown in  FIG. 5 , the upper half partition plate second recessed portion  312  is recessed from an outer peripheral surface of the upper half partition plate body  310  toward the inside in the radial direction Dr. For example, the upper half partition plate second recessed portion  312  is recessed to be formed in a circular shape. The upper half partition plate second recessed portion  312  is formed such that positions thereof in the circumferential direction Dc and the axial direction Da are the same as those of the upper half casing second recessed portion  412  in a state where the upper half partition plate  31  is disposed on the inner peripheral side of the upper half casing  41 . The upper half partition plate second recessed portion  312  includes: an upper half partition plate second flat surface  312   a  facing the outside in the radial direction Dr; and an upper half partition plate second curved surface  312   b  which connects the outer peripheral surface of the upper half partition plate body  310  and the upper half partition plate second flat surface  312   a  to each other. 
     The upper half partition plate second flat surface  312   a  is a flat surface facing upward in the vertical direction Dv. The upper half partition plate second flat surface  312   a  is formed in a circular shape having a diameter smaller than that of the upper half casing second flat surface  412   a  when viewed from the outside in the radial direction Dr. The upper half partition plate second flat surface  312   a  faces the upper half casing second flat surface  412   a  in a state where the upper half partition plate  31  is disposed on the inner peripheral side of the upper half casing  41 . The upper half partition plate second curved surface  312   b  is a concave curved surface which extends in the vertical direction Dv from the outer peripheral surface of the upper half partition plate body  310 . 
     As shown in  FIG. 2 , the lower half partition plate  32  extends in the circumferential direction Dc. The lower half partition plate  32  can be disposed on an inner peripheral side of the lower half casing  42 . The lower half partition plate  32  has lower half partition plate division surfaces  32 X on both ends thereof in the circumferential direction Dc. The lower half partition plate division surface  32 X is the other division surface when the partition plate  3  is divided into upper and lower portions in the vertical direction Dv. The lower half partition plate division surface  32 X is a flat surface which spreads in the radial direction Dr and the axial direction Da. That is, the lower half partition plate division surface  32 X is a horizontal surface facing upward in the vertical direction Dv. The lower half partition plate  32  of the present embodiment includes: a lower half partition plate body  320 ; and a lower half partition plate first recessed portion  391 . 
     In the lower half partition plate body  320 , a cross section orthogonal to the axis Ar is formed in a semicircular annular shape about the axis Ar. The lower half partition plate body  320  can be accommodated in an opening portion of the lower half casing body  420  in a state where a slight gap is provided on the inner peripheral surface side of the lower half casing body  420 . The lower half partition plate body  320  is formed such that an outer diameter thereof is slightly smaller than the inner diameter of the lower half casing body  420 . The outer diameter of the lower half partition plate body  320  is the same as the outer diameter of the upper half partition plate body  310 . The lower half partition plate body  320  is open upward in the vertical direction Dv such that the rotor  2  is fitted into the lower half partition plate body  320 . 
     The lower half partition plate first recessed portion  321  is formed on a bottom portion of the lower half partition plate body  320  in the vertical direction Dv. As shown in  FIG. 6 , the lower half partition plate first recessed portion  321  is recessed from an outer peripheral surface of the lower half partition plate body  320  toward the inside in the radial direction Dr. For example, the lower half partition plate first recessed portion  321  is recessed to be formed in a circular shape. The lower half partition plate first recessed portion  321  is formed such that positions thereof in the circumferential direction Dc and the axial direction Da are the same as those of the lower half casing first recessed portion  421  in a state where the lower half partition plate  32  is disposed on the inner peripheral side of the lower half casing  42 . The lower half partition plate first recessed portion  321  includes: a lower half partition plate second flat surface  322   a  facing the outside in the radial direction Dr; and a lower half partition plate  32  second curved surface which connects the inner peripheral surface of the lower half partition plate body  320  and the lower half partition plate second flat surface  322   a . The lower half partition plate first recessed portion  321  has a shape symmetrical to the upper half partition plate second recessed portion  312  with a horizontal surface passing through the axis Ar as a boundary. 
     The lower half partition plate first flat surface  321   a  is a flat surface facing downward in the vertical direction Dv. The lower half partition plate first flat surface  321   a  is formed in a circular shape having a diameter smaller than that of the lower half casing first flat surface  421   a  when viewed from the outside in the radial direction Dr. The lower half partition plate first flat surface  321   a  faces the lower half casing first flat surface  421   a  in a state where the lower half partition plate  32  is disposed on the inner peripheral side of the lower half casing  42 . The lower half partition plate first curved surface  321   b  is a concave curved surface which extends in the vertical direction Dv from the inner peripheral surface of the lower half partition plate body  320 . 
     As shown in  FIG. 2 , the upper half vertical position defining portions  5  are respectively provided at two locations separated from each other in the horizontal direction Dh. Here, the upper half vertical position defining portion  5 , which is positioned on one side in the horizontal direction Dh which is the right side in the paper surface in  FIG. 2 , is described as an example. In addition, the upper half vertical position defining portion  5  positioned on the other side in the horizontal direction Dh, which is not described, has the same configurations. 
     As shown in  FIG. 3 , the upper half vertical position defining portion  5  defines the positions of the upper half casing  41  and the upper half partition plate  31  in a state where the upper half partition plate division surface  31 X is moveable relative to the upper half casing division surface  41 X to protrude in the vertical direction Dv. The upper half vertical position defining portion  5  regulates a relative movement between the upper half casing  41  and the upper half partition plate  31  in a direction orthogonal to the upper half casing division surface  41 X and the upper half partition plate division surface  31 X. That is, the upper half vertical position defining portion  5  regulates a relative movement between the upper half casing  41  and the upper half partition plate  31  in the vertical direction Dv. The upper half vertical position defining portion  5  of the present embodiment regulates the position of the upper half casing  41  with respect to the upper half partition plate  31  in the vertical direction Dv. Accordingly, the upper half vertical position defining portion  5  causes the upper half casing  41  and the upper half partition plate  31  to be movable relative to each other between position at which the upper half partition plate division surface  31 X protrudes in the vertical direction Dv with respect to the upper half casing division surface  41 X and a position at which the upper half partition plate division surface  31 X does not protrude in the vertical direction Dv with respect to the upper half casing division surface  41 X (a position at which the upper half casing division surface  41 X protrudes in the vertical direction Dv with respect to the upper half partition plate division surface  31 X). Each upper half vertical position defining portion  5  is accommodated in the accommodation space S. The upper half vertical position defining portion  5  includes: an upper half abutment member  51 ; an upper half first fixing member  52 ; and an upper half second fixing member  53 . 
     The upper halt abutment member  51  is fixed to at least one of the upper half casing  41  and the upper half partition plate  31  in the accommodation space S. The upper half abutment member  51  of the present embodiment is attached to both of the upper half casing  41  and the upper half partition plate  31 . The upper half abutment member  51  regulates the relative movement of the upper half casing first flat surface  411   a  with respect to the upper half partition plate first flat surface  311   a  in the vertical direction Dv. The upper half abutment member  51  of the present embodiment regulates the position of the upper half casing first flat surface  411   a  with respect to the upper half partition plate first flat surface  311   a  such that the upper half casing first flat surface  411   a  is not closer to the upper half partition plate division surface  31 X side than the upper half partition plate first flat surface  311   a . Specifically, the upper half abutment member  51  causes the upper half casing first flat surface  411   a  does not further protrude toward the upper half partition plate division surface  31 X side than the upper half partition plate first flat surface  311   a . The upper half abutment member  51  of the present embodiment is a block-shaped member which is formed to have a size which can be accommodated in the accommodation space S. The upper half abutment member  51  includes: an upper half abutment surface  511  which faces the upper half casing first flat surface  411   a  and the upper half partition plate first flat surface  311   a ; an upper half separation surface  512  which is separated from the upper half abutment surface  511  and faces a side opposite to the upper half abutment surface  511 ; an upper half connection side surface  513  which connects the upper half abutment surface  511  and the upper half separation surface  512 ; an upper half abutment member first through-hole  54  which penetrates from the upper half abutment surface  511  to the upper half separation surface  512 ; and an upper half abutment member second through-hole  55  which penetrates from the upper half abutment surface  511  to the upper half separation surface  512  at a position different from that of the upper half abutment member first through-hole  54 . 
     The upper half abutment surface  511  can abut against the upper half casing first flat surface  411   a  and the upper half partition plate first flat surface  311   a . The upper half abutment surface  511  of the present embodiment is a flat surface which is parallel to the upper half casing first flat surface  411   a  and the upper half partition plate first flat surface  311   a . The upper half abutment surface  511  is formed in an elliptical shape. In a state where the upper half assembly  11  is installed on the lower half assembly  12 , the upper half abutment surface  511  is formed at a position at which the upper half abutment surface  511  comes into contact with only the upper half partition plate first flat surface  311   a  and a gap is formed between the upper half abutment surface  511  and the upper half casing first flat surface  411   a.    
     The upper half separation surface  512  is a flat surface which is parallel to the upper half abutment surface  511 . The upper half separation surface  512  is formed in the same shape as that of the upper half abutment surface  511 . That is, the upper half separation surface  512  is formed in an elliptical shape. The upper half separation surface  512  is formed to be closer to the upper half partition plate first flat surface  311   a  side and the upper half casing first flat surface  411   a  side than the upper half partition plate division surface  31 X and the upper half casing division surface  41 X in a state where the upper half abutment member  51  is disposed in the accommodation space S. 
     The upper half connection side surface  513  is a side surface which is orthogonal to the upper half abutment surface  511  and the upper half separation surface  512 . The upper half connection side surface  513  is formed at a position at which a gap is formed between the upper half partition plate first curved surface  311   b  and the upper half casing first curved surface  411   b  in the state where the upper half abutment member  51  is disposed in the accommodation space S. 
     The upper half first fixing member  52  fixes the upper half abutment member  51  to the upper half casing  41 . The upper half first fixing member  52  is a pin member which is fixed to a bolt hole formed on the upper half casing first flat surface  411   a  in a state of being inserted into the upper half abutment member first through-hole  54 . The upper half first fixing member  52  fixes the upper half abutment member  51  in a direction orthogonal to the upper half casing division surface  41 X. The upper half first fixing member  52  fixes the upper half abutment member  51  in a state of being movable with respect to the upper half casing first flat surface  411   a.    
     The upper half second fixing member  53  fixes the upper half abutment member  51  to the upper half partition plate  31 . The upper half first fixing member  52  is a bolt which is fixed to a bolt hole formed on the upper half partition plate first flat surface  311   a  in a state of being inserted into the upper half abutment member second through-hole  55 . The upper half second fixing member  53  fixes the upper half abutment member  51  in a direction orthogonal to the upper half partition plate division surface  31 X. The upper half second fixing member  53  fixes the upper half abutment member  51  in a state of being unmovable while being in contact with the upper half partition plate first flat surface  311   a.    
     As shown in  FIG. 2 , the lower half vertical position defining portions  6  are respectively provided at two locations which are separated from each other in the horizontal direction Dh so as to correspond to the upper half vertical position defining portions  5 . Here, the lower half vertical position defining portion  6 , which is positioned on one side in the horizontal direction Dh which is the right side in the paper surface in  FIG. 2 , is described as an example. In addition, the lower half vertical position defining portion  6  positioned on the other side in the horizontal direction Dh, which is not described, has the same configurations. 
     The lower half vertical position defining portion  6  regulates a relative movement between the lower half casing  42  and the lower half partition plate  32  in a direction orthogonal to the lower half casing division surface  42 X and the lower half partition plate division surface  32 X. The lower half vertical position defining portion  6  of the present embodiment defines the position of the lower half partition plate  32  with respect to the lower half casing  42  such that the lower half casing division surface  42 X and the lower half partition plate division surface  32 X are positioned on the same horizontal surface. The lower half vertical position defining portion  6  of the present embodiment is provided at a position at which the lower half vertical position defining portion  6  is disposed in the accommodation space S in the state where the upper half assembly  11  is installed on the lower half assembly  12 . The lower half vertical position defining portion  6  is formed at a position at which positions thereof in the horizontal direction Dh and the axial direction Da overlap positions of the upper half vertical position defining portion  5  in the horizontal direction Dh and the axial direction Da. The lower half vertical position defining portion  6  includes: a lower half abutment member  61 ; and a lower half first fixing member  62 . 
     The lower half abutment member  61  is fixed to at least one of the lower half casing  42  and the lower half partition plate  32 . The lower half abutment member  61  of the present embodiment is fixed to only the lower half partition plate  32 . The lower half abutment member  61  is disposed on the same horizontal surface as those of the lower half casing division surface  42 X and the lower half partition plate division surface  32 X. Accordingly, the lower half abutment member  61  defines the position of the lower half casing division surface  42 X with respect to the lower half partition plate division surface  32 X in the Vertical direction Dv such that the lower half casing division surface  42 X is always positioned on the same horizontal surface as that of the lower half partition plate division surface  32 X. The lower half abutment member  61  of the present embodiment is a block-shaped member which is formed to have a size which can be accommodated in the accommodation space S together with the upper half abutment member  51 . The lower half abutment member  61  includes: a lower half abutment surface  611  which faces the lower half casing division surface  42 X and the lower half partition plate division surface  32 X; a lower half separation surface  612  which is separated front the lower half abutment surface  611  and faces a side opposite to the lower half abutment surface  611 ; a lower half connection side surface  613  which connects the lower half abutment surface  611  and the lower half separation surface  612  to each other; and a lower half abutment member first through-hole  63  which penetrates from the lower half abutment surface  611  to the lower half separation surface  612 . 
     The lower half abutment surface  611  can abut against the lower half casing division surface  42 X and the lower half partition plate division surface  32 X. The lower half abutment surface  611  of the present embodiment is a flat surface which is parallel to the lower half casing first flat surface  421   a  and the lower half partition plate first flat surface  321   a . The lower half abutment surface  611  is formed in a circular shape. The lower half abutment surface  611  abuts against both the lower half casing division surface  42 X and the lower half partition plate division surface  32 X. 
     The lower half separation surface  612  is a flat surface which is parallel to the lower half abutment surface  611 . The lower half separation surface  612  is formed in the same shape as that of the lower half abutment surface  611 . That is, the lower half separation surface  612  is formed in a circular shape. The lower half separation surface  612  is disposed to be closer to the upper half partition plate first flat surface  311   a  and the upper half casing first flat surface  411   a  than the lower half partition plate division surface  32 X and the lower half casing division surface  42 X in a state where the lower half abutment member  61  is disposed in the accommodation space S. The lower half separation surface  612  is formed at a position at which the lower half separation surface  612  does not interfere with the upper half abutment member  51  in the vertical direction Dv in a state where the lower half abutment member  61  is disposed in the accommodation space S. 
     The lower half connection side surface  613  is a side surface which is orthogonal to the lower half abutment surface  611  and the lower half separation surface  612 . The lower half connection side surface  613  is formed at a position at which a gap is formed between the upper half partition plate first curved surface  311   b  and the upper half casing first curved surface  411   b  in a state where the lower half abutment member  61  is disposed in the accommodation space S. 
     The lower half first fixing member  62  fixes the lower half abutment member  61  to the lower half partition plate  32 . The lower half first fixing member  62  is a bolt which is fixed to a bolt hole formed on the lower half casing first flat surface  421   a  in a state of being inserted into the lower half abutment member first through-hole  63 . The lower half first fixing member  62  fixes the lower half abutment member  61  in a direction orthogonal to the lower half partition plate division surface  32 X. The lower half first fixing member  62  fixes the lower half abutment member  61  in a state of being unmovable while being in contact with the lower half partition plate first flat surface  321   a.    
     As shown in  FIG. 2 , the upper half horizontal position defining portion  7  is formed on top portions of the upper half casing body  410  and the upper half partition plate body  310  in the vertical direction Dv. The upper half horizontal position defining portion  7  defines a position of the upper half partition plate  31  with respect to the upper half casing  41  in the horizontal direction Dh. Accordingly, the upper half horizontal position defining portion  7  regulates a relative movement between the upper half casing  41  and the upper half partition plate  31  in a direction parallel to the upper half casing division surface  41 X and the upper half partition plate division surface  31 X. As shown in  FIG. 5 , the upper half horizontal position defining portion  7  of the present embodiment is provided in the upper half casing second recessed portion  412  and the upper half partition plate second recessed portion  312 . The upper half horizontal position defining portion  7  includes: an upper half horizontal first abutment portion  71  which is inserted into the upper half casing second recessed portion  412 ; an upper half horizontal second abutment portion  72  which is inserted into the upper half partition plate second recessed portion  312 ; and an upper half horizontal fixing member  73  which fixes the upper half horizontal first abutment portion  71  and the upper half horizontal second abutment portion  72 . 
     The upper half horizontal first abutment portion  71  is fitted into the upper half casing second recessed portion  412 . The upper half horizontal first abutment portion  71  is formed in a disk shape corresponding to the upper half casing second recessed portion  412 . The upper half horizontal first abutment portion  71  includes: an upper half horizontal first abutment flat surface  71   a  which faces the upper half casing second flat surface  412   a ; and an upper half horizontal first abutment curved surface  71   b  which faces the upper half casing second curved surface  412   b.    
     The upper half horizontal first abutment flat surface  71   a  is a flat surface which abuts against the upper half casing second flat surface  412   a . The upper half horizontal first abutment flat surface  71   a  is formed in a circular shape having the same diameter as that of the upper half casing second flat surface  412   a  when viewed in the radial direction Dr. The upper half horizontal first abutment curved surface  71   b  is a concave curved surface which abuts against the upper half casing second curved surface  412   b.    
     The upper half horizontal second abutment portion  72  is formed in a disk shape corresponding to the upper half partition plate second recessed portion  312 . The upper half horizontal second abutment portion  72  is formed in a disk shape having a diameter smaller than that of the upper half horizontal first abutment portion  71 . The upper half horizontal second abutment portion  72  includes: an upper half horizontal second abutment flat surface  72   a  which faces the upper half partition plate second flat surface  312   a ; and an upper half horizontal second abutment curved surface  72   b  which faces the upper half partition plate second curved surface  312   b.    
     The upper half horizontal second abutment flat surface  72   a  is a flat surface which is separated from the upper half partition plate second flat surface  312   a  and faces the upper half partition plate second flat surface  312   a . The upper half horizontal second abutment flat surface  72   a  is formed in a circular shape having the same diameter as that of the upper half partition plate second flat surface  312   a  when viewed in the radial direction Dr. The upper half horizontal second abutment curved surface  72   b  is a concave curved surface which abuts against the upper half partition plate second curved surface  312   b.    
     The upper half horizontal fixing member  73  fixes the upper half horizontal first abutment portion  71  and the upper half horizontal second abutment portion  72  to the upper half casing  41 . The upper half horizontal fixing member  73  is a bolt which is fixed to a bolt hole formed on the upper half partition plate second flat surface  312   a  in a state of penetrating the upper half horizontal first abutment portion  71  and the upper half horizontal second abutment portion  72 . The upper half horizontal fixing member  73  fixes the upper half horizontal first abutment portion  71  and the upper half horizontal second abutment portion  72  in a state where the upper half horizontal first abutment flat surface  71   a  is unmovable while being in contact with the upper half partition plate second flat surface  312   a.    
     As shown in  FIG. 2 , the lower half horizontal position defining portion  8  is formed on bottom portions of the lower half casing body  420  and the lower half partition plate body  320  in the vertical direction Dv. The lower half horizontal position defining portion  8  defines a position of the lower half partition plate  32  with respect to the lower half casing  42  in the horizontal direction Dh. Accordingly, the lower half horizontal position defining portion  8  regulates a relative movement between the lower half casing  42  and the lower half partition plate  32  in a direction parallel to the lower half casing division surface  42 X and the lower half partition plate division surface  32 X. As shown in  FIG. 6 , the lower half horizontal position defining portion  8  of the present embodiment is provided in the lower half casing second recessed portion  422  and the lower half partition plate second recessed portion  322 . The lower half horizontal position defining portion  8  is formed in the same shape as that of the upper half horizontal position defining portion  7 . The lower half horizontal position defining portion  8  includes: a lower half horizontal first abutment portion  81  which is inserted into the lower half casing first recessed portion  421 ; a lower half horizontal second abutment portion  82  which is inserted into the lower half partition plate first recessed portion  321 ; and a lower half horizontal fixing member  83  which fixes the lower half horizontal first abutment portion  81  and the lower half horizontal second abutment portion  82 . 
     The lower half horizontal first abutment portion  81  is fitted into the lower half casing first recessed portion  421 . The lower half horizontal first abutment portion  81  is formed in a disk shape corresponding to the lower half casing first recessed portion  421 . The lower half horizontal first abutment portion  81  includes: a lower half horizontal first abutment flat surface  81   a  which faces the lower half casing first flat surface  421   a ; and a lower half horizontal first abutment curved surface  81   b  which faces the lower half casing first curved surface  421   b.    
     The lower half horizontal first abutment at surface  81   a  is a flat surface which abuts against the lower half casing first flat surface  421   a . The lower half horizontal first abutment flat surface  81   a  is formed in a circular shape having the same diameter as that of the lower half casing first flat surface  421   a  when viewed from the inside in the radial direction Dr. The lower half horizontal first abutment curved surface  81   b  is a concave curved surface which abuts against the lower half casing first curved surface  421   b.    
     The lower half horizontal second abutment portion  82  is formed in a disk shape corresponding to the lower half partition plate first recessed portion  321 . The lower half horizontal second abutment portion  82  is formed in a disk shape having a diameter smaller than that of the lower half horizontal first abutment portion  81 . The lower half horizontal second abutment portion  82  includes: a lower half horizontal second abutment flat surface  82   a  which faces the lower half partition plate first flat surface  321   a ; and a lower half horizontal second ab merit curved surface  82   b  which faces the lower half partition plate first curved surface  321   b.    
     The lower half horizontal second abutment flat surface  82   a  is a flat surface which is separated from the lower half partition plate first flat surface  321   a  and faces the lower half partition plate first flat surface  321   a . The lower half horizontal second abutment flat surface  82   a  is formed in a circular shape having the same diameter as that of the lower half partition plate first flat surface  321   a  when viewed from the inside in the radial direction Dr. The lower half horizontal second abutment curved surface  82   b  is a concave curved surface which abuts against the lower half partition plate first curved surface  321   b.    
     The lower half horizontal fixing member  83  fixes the lower half horizontal first abutment portion  81  and the lower half horizontal second abutment portion  82  to the lower half casing  42 . The lower half horizontal fixing member  83  is a bolt which is fixed to a bolt hole formed on the lower half partition plate first flat surface  321   a  in a state of penetrating the lower half horizontal first abutment portion  81  and the lower half horizontal second abutment portion  82 . The lower half horizontal fixing member  83  fixes the lower half horizontal first abutment portion  81  and the lower half horizontal second abutment portion  82  in a state where the lower half horizontal first abutment flat surface  81   a  is unmovable while being in contact with the lower half partition plate first flat surface  321   a.    
     Next, a steam turbine assembling method S 1  for assembling the steam turbine  1  will be described. In the present embodiment, a steam turbine assembling method in a case where each part is assembled from the be inning to manufacture the steam turbine  1  will be described. In addition, it should be noted that the present invention is not limited only to the case of manufacturing the steam turbine  1  from the beginning and the steam turbine assembling method S 1  may be used when disassembling and assembling the steam turbine  1  for repair or inspection. 
     As shown in  FIG. 7 , the steam turbine assembling method S 1  of the present embodiment includes: an upper half casing preparation step S 2 ; an upper half partition plate preparation step S 3 ; a lower half casing preparation step S 4 ; a lower half partition plate preparation step S 5 ; an upper half assembling step S 6 ; a lower half assembling step S 7 ; and a final assembling step S 8 . 
     In the upper half casing preparation step S 2 , the upper half casing  41  is prepared. In the upper half casing preparation step S 2  of the present embodiment, the upper half casing  41  is prepared by forming the upper half casing  41 . The upper half casing preparation step S 2  of the present embodiment includes: an upper half casing body forming step S 21 ; and an upper half casing recessed portion forming step S 22 . 
     In the upper half casing body forming step S 21 , the upper half casing body  410  is formed. 
     In the upper half casing recessed portion forming step S 22 , the upper half casing first recessed portions  411  and the upper half casing second recessed portion  412  are formed. The upper half casing recessed portion forming step S 22  is performed after the upper half casing body forming step S 21 . In the upper half casing recessed portion forming step S 22 , each upper half easing first flat surface  411   a  is formed to be parallel to each upper half casing division surface  41 X. In the upper half casing recessed portion forming step S 22 , the upper half casing second flat surface  412   a  is formed to be parallel to the upper half casing division surface  41 X. 
     In the upper half partition plate preparation step S 3 , the upper half partition plate  31  is prepared. In the upper half partition plate preparation step S 3  of the present embodiment, the upper half partition plate  31  is prepared by forming the upper half partition plate  31 . The upper half partition plate preparation step S 3  of the present embodiment includes: an upper half partition plate body forming step S 31 ; and the upper half partition plate recessed portion forming step S 32 . 
     In the upper half partition plate body forming step S 31 , the upper half partition plate body  310  is formed. 
     In the upper half partition plate recessed portion forming step S 32 , the upper half partition plate first recessed portions  311  and the upper half partition plate second recessed portion  312  are formed. The upper half partition plate recessed portion forming step S 32  is performed after the upper half partition plate body forming step S 31 . In the upper half partition plate recessed portion forming step S 32 , each upper half partition plate first flat surface  311   a  is formed to be parallel to each upper half partition plate division surface  31 X. In the upper half partition plate recessed portion forming step S 32 , the upper half partition plate second flat surface  312   a  is formed to be parallel to the upper half partition plate division surface  31 X. 
     In the lower half casing preparation step S 4 , the lower half casing  42  is prepared. In the lower half casing preparation step S 4  of the present embodiment, the lower half casing  42  is prepared by forming the lower half casing  42 . The lower half casing preparation step S 4  of the present embodiment includes: a lower half casing body forming step S 41 ; and a lower half casing recessed portion forming step S 42 . 
     In the lower half casing body forming step S 41 , the lower half casing body  420  is formed. 
     In the lower half casing recessed portion forming step S 42 , the lower half casing first recessed portions  421  is formed. The lower half casing recessed portion forming step S 42  is performed after the lower half casing body forming step S 41 . In the lower half casing recessed portion forming step S 42 , each lower half casing first flat surface  421   a  is formed to be parallel to each lower half casing division surface  42 X. 
     In the lower half partition plate preparation step S 5 , the lower half partition plate  32  is prepared. In the lower half partition plate preparation step S 5 , the lower half partition plate  32  is prepared by forming the lower half partition plate  32 . The lower half partition plate preparation step S 5  of the present embodiment includes: a lower half partition plate body forming step S 51 ; and the lower half partition plate recessed portion forming step S 52 . 
     In the lower half partition plate body forming step S 51 , the lower half partition plate body  320  is formed. 
     In the lower half partition plate recessed portion forming step S 52 , the lower half partition plate first recessed portion  321  is formed. The lower half partition plate recessed portion forming step S 52  is performed after the lower half partition plate body forming step S 51 . In the lower half partition plate recessed portion forming step S 52 , the lower half partition plate second flat surface  322   a  is formed to be parallel to the lower half partition plate division surface  32 X. 
     In addition, the above-described upper half casing preparation step S 2 , the upper half partition plate preparation step S 3 , the lower half casing preparation step S 4 , and the lower half partition plate preparation step S 5  may be performed from any step, and thus, the steps may be performed according to any order. Therefore, respective steps may be performed in parallel. In addition, in the upper half casing preparation step S 2 , the upper half partition plate preparation step S 3 , the lower half casing preparation step S 4 , and the lower half partition plate preparation step S 5 , each member may not be formed and may be prepared in advance. 
     The upper half assembling step S 6  is performed after the upper half casing preparation step S 2  and the upper half partition plate preparation step S 3 . In the upper half assembling step S 6 , the upper half partition plate  31  is disposed on the inner peripheral side of the upper half casing  41  so as to form the upper half assembly  11 . After the upper half partition plate  31  is disposed on the inner peripheral side of the upper half casing  41 , the upper half vertical position defining portions  5  are attached to at least one of the upper half casing  41  and the upper half partition plate  31 . Accordingly, in the upper half assembling step S 6 , in a state where a predetermined gap is provided between an inner peripheral surface of the upper half casing  41  and an outer peripheral surface of the upper half partition plate  31 , the upper half assembly  11  in which positions thereof in the vertical direction Dv and the horizontal direction Dh are defined such that center positions of the upper half casing  41  and the upper half partition plate  31  are aligned with each other is formed. Specifically, the upper half assembling step S 6  of the present embodiment includes: an upper half casing disposition step S 61 ; an upper half partition plate disposition step S 62 ; an upper half horizontal position defining step S 63 ; and an upper half vertical position defining step S 64 . 
     In the upper half casing disposition step S 61 , the upper half casing  41  is disposed in a state where the upper half casing division surface  41 X faces upward in the vertical direction Dv. 
     In the upper half partition plate disposition step S 62 , the upper half partition plate  31  is disposed on the inner peripheral side of the upper half casing  41  in a state where the upper half partition plate division surface  31 X faces upward in the vertical direction Dv. In the upper half partition plate disposition step S 62 , the upper half partition plate  31  is disposed such that the accommodation space S is formed by aligning the positions of the upper half casing first recessed portion  411  and the upper half partition plate first recessed portion  311 . 
     In the upper half horizontal position defining step S 63 , the position of the upper half partition plate  31  with respect to the upper half casing  41  in the horizontal direction Dh is defined. In the upper half horizontal position defining step S 63 , the upper half horizontal position defining portion  7  is fitted into the upper half casing second recessed portion  412  and the upper half partition plate second recessed portion  312 . In the upper half horizontal position defining step S 63  of the present embodiment, the upper half partition plate  31  is lifted in the vertical direction Dv, and the upper half horizontal first abutment portion  71  is fitted into and fixed to the upper half casing second recessed portion  412  in a state of being unmovable with respect to the upper half casing second recessed portion  412 . Thereafter, in a state where the upper half partition plate  31  is lifted in the vertical direction Dv, the upper half horizontal second abutment curved surface  72   b  or the upper half partition plate second curved surface  312   b  is cut off. Accordingly, a horizontal position of the upper half partition plate  31  with respect to the upper half casing  41  is adjusted. 
     In the upper half vertical position defining step S 64 , the position of the upper half partition plate  31  with respect to the upper half casing  41  in the vertical direction Dv is defined. The upper half vertical position defining step S 64  is performed after the upper half partition plate disposition step S 62 . In the upper half vertical position defining step S 64 , as the upper half vertical position defining portion  5 , the upper half abutment member  51  is provided in the accommodation space S. In the upper half vertical position defining step S 64 , in a state where the upper half abutment surface  511  abuts against at least one of the upper half casing first flat surface  411   a  and the upper half partition plate first flat surface  311   a  and in a state where the upper half abutment surface  511  is relatively movable with respect to the other of the upper half casing first flat surface  411   a  and the upper half partition plate first flat surface  311   a  in the vertical direction Dv, the upper half abutment member  51  is fixed. In the upper half vertical position defining step S 64  of the present embodiment, in a state where the upper half partition plate division surface  31 X further protrudes than the upper half casing division surface  41 X, the upper half abutment surface  511  abuts against the upper half casing first flat surface  411   a  and the upper half partition plate first flat surface  311   a , and thus, the upper half abutment member  51  is fixed. Specifically, after the horizontal position is defined in the upper half horizontal position defining step S 63 , the upper half abutment member  51  is disposed in a state where the upper half abutment surface  511  abuts against the upper half partition plate first flat surface  311   a  and the upper half partition plate first flat surface  311   a . Thereafter, in a state where the upper half partition plate first flat surface  311   a  and the upper half abutment surface  511  come into contact with each other, the upper half abutment member  51  is fixed in a state of being unmovable with respect to the upper half partition plate first flat surface  311   a . In addition, after the upper half abutment member  51  is fixed to the upper half partition plate  31 , in a state where the upper half casing first flat surface  411   a  and the upper half abutment surface  511  come into contact with each other, the upper half abutment member  51  is fixed in a state of being movable with respect to the upper half casing first flat surface  411   a.    
     The lower half assembling step S 7  is performed after the lower half casing preparation step S 4  and the lower half partition plate preparation step S 5 . In the lower half assembling step S 7 , the lower half partition plate  32  is disposed on the inner peripheral side of the lower half casing  42  to form the lower half assembly  12 . After the lower half partition plate  32  is disposed on the inner peripheral side of the lower half casing  42 , the lower half vertical position defining portion  6  is attached to at least one of the lower half casing  42  and the lower half partition plate  32 . Accordingly, in the lower half assembling step S 7 , in a state where a predetermined gap is provided between the inner peripheral surface of the lower half casing  42  and the outer peripheral surface of the lower half partition plate  32 , the lower half assembly  12  in which positions thereof in the vertical direction Dv and the horizontal direction Dh are defined such that center positions of the lower half casing  42  and the lower half partition plate  32  are aligned with each other is formed. Specifically, the lower half assembling step S 7  of the present embodiment includes: a lower half casing disposition step S 71 ; a lower half partition plate disposition step S 72 ; a lower half horizontal position defining step S 73 ; and a lower half vertical position defining step S 74 . 
     In the lower half casing disposition step S 71 , the lower half casing  42  is disposed in a state where the lower half casing division surface  42 X faces upward in the vertical direction Dv. 
     In the lower half partition plate disposition step S 72 , the lower half partition plate  32  is disposed on the inner peripheral side of the lower half casing  42  in a state where the lower half partition plate division surface  32 X faces upward in the vertical direction Dv. 
     In the lower half horizontal position defining step S 73 , the position of the lower half partition plate  32  with respect to the lower half casing  42  in the horizontal direction Dh is defined. In the lower half horizontal position defining step S 73 , the lower half horizontal position defining portion  8  is fitted into the lower half casing second recessed portion  422  and the lower half partition plate second recessed portion  322 . In the lower half horizontal position defining step S 73  of the present embodiment, the lower half partition plate  32  is lifted in the vertical direction Dv, and the lower half horizontal first abutment portion  81  is fitted into the lower half casing second recessed portion  422  in a state of being unmovable with respect to the lower half casing second recessed portion  422 . Thereafter, in a state where the lower half partition plate  32  is lifted in the vertical direction Dv, the lower half horizontal second abutment curved surface  82   b  or the lower half partition plate  32  second curved surface is cut off. Accordingly, a horizontal position of the lower half partition plate  32  with respect to the lower half casing  42  is adjusted. 
     In the lower half vertical position defining step S 74 , the position of the lower half partition plate  32  with respect to the lower half casing  42  in the vertical direction Dv is defined. The lower half vertical position defining step S 74  is performed after the lower half partition plate disposition step S 72 . In the lower half vertical position defining step S 74 , as the lower half position defining portion, the lower half abutment member  61  is provided. In the lower half vertical position defining step S 74 , in a state where the lower half abutment surface  611  abuts against the lower half casing division surface  42 X and the lower half partition plate division surface  32 X, the lower half abutment member  61  is fixed to at least one of the lower half casing  42  and the lower half partition plate  32 . In the lower half vertical position defining step S 74  of the present embodiment, the lower half abutment member  61  is disposed so as to extend over the lower half casing division surface  42 X and the lower half partition plate division surface  32 X. Thereafter, the lower half abutment surface  611  abuts against the lower half casing division surface  42 X and the lower half partition plate division surface  32 X, and the lower half abutment member  61  is fixed to the lower half partition plate  32  in a state of being unmovable with respect to the lower half partition plate  32 . 
     In the final assembling step S 8 , the upper half casing division surface  41 X abuts against the lower half casing division surface  42 X so as to install the upper half assembly  11  on the lower half assembly  12 . Specifically, in the final assembling step S 8 , the rotor  2  is disposed on the lower half assembly  12 . In a state where the rotor  2  is disposed, the upper half assembly  11 , in which the upper half partition plate division surface  31 X is movable to protrude in the vertical direction Dv with respect to the upper half casing division surface  41 X, is placed on the lower half assembly  12 . In this case, the upper half casing division surface  41 X abuts against the lower half casing division surface  42 X, and thus, the upper half partition plate division surface  31 X which further protrudes than the upper half casing division surface  41 X is pushed by the lower half partition plate division surface  32 X. As a result, the upper half partition plate  31  moves with respect to the upper half casing  41  in a state where the upper half partition plate division surface  31 X abuts against the lower half partition plate division surface  32 X. Accordingly, the steam turbine  1  is formed in a state where the upper half casing division surface  41 X abuts against the lower half casing division surface  42 X and the upper half partition plate division surface  31 X abuts against the lower half partition plate division surface  32 X. 
     According to the above-described steam turbine assembling method S 1 , the steam turbine  1 , and the lower half assembly  12 , the lower half vertical position defining portion  6  is attached after the lower half partition plate  32  is disposed on the inner peripheral side of the lower half casing  42 . Specifically, by the tower half vertical position defining portion  6 , the tower half abutment member  61  is fixed in the state where the lower half abutment surface  611  abuts against the lower half casing division surface  42 X and the lower half partition plate division surface  32 X. Thus, by the lower half vertical position defining portion  6  which makes the lower half casing division surface  42 X and the lower half partition plate division surface  32 X come into contact with the lower half abutment surface  611  to be disposed on the same horizontal surface, the lower half casing division surface  42 X and the lower half partition plate division surface  32 X are disposed on the same horizontal surface. Accordingly, the positions of the lower half casing division surface  42 X and the lower half partition plate division surface  32 X can be defined in a state where the lower half casing  42  and the lower half partition plate  32  are assembled together. 
     In addition, the lower half abutment member  61  is fixed to the lower half partition plate  32 , and thus, the state where the lower half casing division surface  42 X and the lower half partition plate division surface  32 X are disposed on the same horizontal surface as each other is maintained. Accordingly, by only fixing the lower half abutment member  61  to the lower half partition plate  32 , it is possible to define the positions of the lower half casing  42  and the lower half partition plate in the vertical direction Dv while decreasing the amount of adjustment needed in positioning of the lower half assembly  12 . The lower half casing division surface  42 X and the lower half partition plate division surface  32 X are supported on the same horizontal surface, and thus, it is possible to suppress occurrence of a gap between the upper half assembly  11  and the lower half assembly  12 . 
     In addition, the lower half abutment member  61  is disposed so as to be positioned in the accommodation space S. Accordingly, when the upper half assembly  11  and the lower half assembly  12  are combined with each other, it is possible to prevent the lower half abutment member  61  from being disposed between the lower half partition plate division surface  32 X and the upper half partition plate division surface  31 X or at an interference position between the lower half partition plate division surface  32 X and the upper half partition plate division surface  31 X. Therefore, when the lower half assembly  12  rind the upper half assembly  11  are combined with each other, itis possible to prevent the lower half abutment member  61  from becoming an obstacle. 
     In addition, the upper half vertical position defining portions  5  are attached after the upper half partition plate  31  is disposed on the inner peripheral side of the upper half casing  41 . The upper half vertical position defining portions  5  make the upper half partition plate division surface  31 X be movable relative to the upper half casing division surface  41 X such that the upper half partition plate division surface  31 X protrudes with respect to the upper half casing division surface  41 X in the vertical direction Dv. Accordingly, the positions of the upper half casing division surface  41 X and the upper half partition plate division surface  31 X can be defined in a state where the upper half casing  41  and the upper half partition plate  31  are assembled together. 
     In addition, when the lower half assembly  12  and the upper half assembly  11  are combined with each other, the upper half partition plate division surface  31 X and the upper half casing division surface  41 X faces downward in the vertical direction Dv. As a result, the upper half partition plate  31  is lowered by its own weight in a state where the movement thereof is regulated by the upper half abutment member  51 , and the upper half partition plate division surface  31 X further protrudes downward in the vertical direction Dv than the upper half casing division surface  41 X. Accordingly, when the upper half assembly  11  is placed on the lower half assembly  12  while the upper half casing division surface  41 X abuts against the lower half casing division surface  42 X, the lower half partition plate division surface  32 X and the upper half partition plate division surface  31 X come into contact with each other at high accuracy. Thereafter, the upper half partition plate  31  moves relative to the upper half casing  41  in the vertical direction Dv in a state where the lower half partition plate division surface  32 X and the upper half partition plate division surface  31 X come into contact with each other. As a result, in a state where the upper half partition plate division surface  31 X and the lower half partition plate division surface  32 X come into contact with each other, the upper half casing division surface  41 X and the lower half casing division surface  42 X come into contact with each other, and the lower half assembly  12  and the upper half assembly  11  are combined with each other. Accordingly, by only placing the upper half assembly  11  on the lower half assembly  12 , the lower half partition plate division surface  32 X and the upper half partition plate division surface  31 X can come into contact with the lower half partition plate division surface  32 X and the upper half partition plate division surface  31 X at high accuracy. Accordingly, it is possible to suppress occurrence of a gap between the upper half assembly  11  and the lower half assembly  12  while decreasing the amount of adjustment needed in positioning. 
     In addition, the upper half abutment member  51  is fixed in the state where the upper half partition plate first flat surface  311   a  and the upper half abutment surface  511  abut against each other and in the state where the upper half abutment surface  511  is movable with respect to the upper half casing first flat surface  411   a  in the vertical direction Dv. Accordingly, after the upper half casing  41  and the upper half partition plate  31  are assembled together, the upper half partition plate  31  and the upper half casing  41  are connected to each other to be movable via the upper half abutment member  51 . Therefore, by the upper half abutment member  51 , the upper half partition plate division surface  31 X can be made movable so as to protrude in the vertical direction Dv with respect to the upper half casing division surface  41 X. Accordingly, the adjustment needed in positioning can be easily performed by only fixing the upper half abutment member  51 . 
     In addition, the upper half abutment member  51  is disposed in the accommodation space S. Accordingly, the upper half abutment member  51  can be disposed so as not to protrude from the upper half casing division surface  41 X and the upper half partition plate division surface  31 X. Accordingly, when the lower half assembly  12  and the upper half assembly  11  are combined with each other, it is possible to prevent the upper half abutment member  51  from being disposed between the lower half partition plate division surface  32 X and the upper half partition plate division surface  31 X or at an interference position between the lower half partition plate division surface  32 X and the upper half partition plate division surface  31 X. Therefore, when the lower half assembly  12  and the upper half assembly  11  are combined together, it is possible to prevent the upper half abutment member  51  from becoming an obstacle. 
     In addition, the upper half abutment member  51  is disposed in a state where the upper half partition plate division surface  31 X faces upward in the vertical direction Dv. Accordingly, a worker can attach the upper half abutment member  51  to the upper half partition plate  31  and the upper half casing  41  from the upper portion in the vertical direction Dv. Therefore, when the upper half abutment member  51  is fixed to the upper half partition plate  31  or the upper half casing  41 , it is unnecessary to perform a work so as to get the upper half abutment member  51  in from the lower portion in the vertical direction Dv with respect to the upper half partition plate  31  and the upper half casing  41 . As a result, the upper half abutment member  51  is easily attached to the upper half partition plate  31  and the upper half casing  41 . 
     In addition, the upper half casing first flat surface  411   a  and the upper half casing division surface  41 X are formed to be parallel to each other, and the upper half partition plate first flat surface  311   a  and the upper half partition plate division surface  31 X are formed to be parallel to each other. Accordingly, by only adjusting the positions of the parallel surfaces of the upper half casing first flat surface  411   a  and the upper half casing division surface  41 X in the vertical direction Dv and the positions of the parallel surfaces of the upper half partition plate first flat surface  311   a  and the upper half partition plate division surface  31 X in the vertical direction Dv, the positions of the upper half casing division surface  41 X and the upper half partition plate division surface  31 X are adjusted when the upper half abutment member  51  is attached. Therefore, it is possible to easily perform delicate adjustment of a protrusion amount of the upper half partition plate division surface  31 X with respect to the upper half casing division surface  41 X. 
     In addition, in the upper half vertical position defining step S 64 , the upper half abutment surface  511  abuts against the upper half casing first flat surface  411   a  and the upper half partition plate first flat surface  311   a , and thus, the upper half abutment member  51  is fixed. Accordingly, when the upper half abutment member  51  is attached, it is not necessary to finely adjust the position of the upper half abutment surface  511  with respect to the upper half casing first flat surface  411   a  and the upper half partition plate first flat surface  311   a . Therefore, it is possible to easily attach the upper half abutment member  51  to the upper half partition plate  31  and the upper half casing  41 . 
     Hereinbefore, the embodiments of the present invention are described with reference to the drawings. However, configurations and a combination thereof in each embodiment are examples, and addition, omission, replacement, and other modifications of the configurations can be made within a scope which does not depart from the gist of the present invention. In addition, the present invention is not limited to the embodiments and is limited by only claims. 
     INDUSTRIAL APPLICABILITY 
     The steam turbine assembling method, the steam turbine, and the lower half assembly described above make it possible to suppress the occurrence of a gap between the upper half assembly  11  and the lower half assembly  12  while decreasing the amount of adjustment needed in positioning. 
     DESCRIPTION OF REFERENCE NUMERALS 
     
         
         
           
               1 : steam turbine 
             Ar: axis 
             Da: axial direction 
             Dr: radial direction 
             Dc: circumferential direction 
             Dv: vertical direction 
             Dh: horizontal direction 
               2 : rotor 
               21 : rotor shaft 
               22 : rotor blade 
               3 : partition plate 
               30 : stator blade 
               31 : upper half partition plate 
               310 : upper half partition plate body 
               311 : upper half partition plate first recessed portion 
               311   a : upper half partition plate first flat surface 
               311   b : upper half partition plate first curved surface 
               312 : upper half partition plate second recessed portion 
               312   a : upper half partition plate second flat surface 
               312   b : upper half partition plate second curved surface 
               31 X: upper half partition plate division surface 
               32 : lower half partition plate 
               320 : lower half partition plate body 
               321 : lower half partition plate first recessed portion 
               321   a : lower half partition plate first flat surface 
               321   b : lower half partition plate first curved surface 
               32 X: lower half partition plate division surface 
               4 : casing 
               41 : upper half casing 
               410 : upper half casing body 
               411 : upper half casing first recessed portion 
               411   a : upper half casing first flat surface 
               411   b : upper half casing first curved surface 
               412 : upper half casing second recessed portion 
               412   a : upper half casing second flat surface 
               412   b : upper half casing second curved surface 
               41 X: upper half casing division surface 
               42 : lower half casing 
               420 : lower half casing body 
               421 : lower half casing first recessed portion 
               421   a : lower half casing first flat surface 
               421   b : lower half casing first curved surface 
               42 X: lower half casing division surface 
               5 : upper half vertical position defining portion 
               51 : upper half abutment member 
               511 : upper half abutment surface 
               512 : upper half separation surface 
               513 : upper half connection side surface 
               52 : upper half first fixing member 
               53 : upper half second fixing member 
               54 : upper half abutment member first through-hole 
               55 : upper half abutment member second through-hole 
               6 : lower half vertical position defining portion 
               61 : lower half abutment member 
               611 : lower half abutment surface 
               612 : lower half separation surface 
               613 : lower half connection side surface 
               62 : lower half first fixing member 
               63 : lower half abutment member first through-hole 
               7 : upper half horizontal position defining portion 
               71 : upper half horizontal first abutment portion 
               71   a : upper half horizontal first abutment flat surface 
               71   b : upper half horizontal first abutment curved surface 
               72 : upper half horizontal second abutment portion 
               72   a : upper half horizontal second abutment flat surface 
               72   b : upper halt horizontal second abutment curved surface 
               73 : upper half horizontal fixing member 
               8 : lower half horizontal position defining portion 
               81 : lower half horizontal first abutment portion 
               81   a : lower half horizontal first abutment flat surface 
               81   b : lower half horizontal first abutment curved surface 
               82 : lower half horizontal second abutment portion 
               82   a : louver half horizontal second abutment flat surface 
               82   b : lower half horizontal second abutment curved surface 
               83 : lower half horizontal fixing member 
               11 : upper half assembly 
               12 : lower half assembly 
             S: accommodation space 
             S 1 : steam turbine assembling method 
             S 2 : upper half casing preparation step 
             S 21 : upper half casing body forming step 
             S 22 : upper half casing recessed portion forming step 
             S 3 : upper half partition plate preparation step 
             S 31 : upper half partition plate body forming step 
             S 32 : upper half partition plate recessed portion forming step 
             S 4 : lower half casing preparation step 
             S 41 : lower half casing body forming step 
             S 42 : lower half casing recessed portion forming step 
             S 5 : lower half partition plate preparation step 
             S 51 : lower half partition plate body forming step 
             S 52 : lower half partition plate recessed portion forming step 
             S 6 : upper half assembling step 
             S 61 : upper half casing disposition step 
             S 62 : upper half partition plate disposition step 
             S 63 : upper half horizontal position defining step 
             S 64 : upper half vertical position defining step 
             S 7 : lower half assembling step 
             S 71 : lower half casing disposition step 
             S 72 : lower half partition plate disposition step 
             S 73 : lower half horizontal position defining step 
             S 74 : lower half vertical position defining step 
             S 8 : final assembling step