TECHNICAL FIELD
[0001] The present disclosure relates to a maintenance method for a steam turbine and a
steam turbine.
The present application claims priority based on Japanese Patent Application No. 2020-
093637 filed on May 28, 2020, the entire content of which is incorporated herein by reference.
10
BACKGROUND ART
[0002] In maintenance of a steam turbine, a rotor may be lifted to remove internal
components (e.g., bearing) from a casing in which the rotor is housed, and an expansion
member such as a hydraulic jack may be used for this purpose.
15 [0003] Patent Document 1 does not relate to maintenance, but Patent Document 1 describes
assisting the lifting of a turbine rotor with a jack installed inside a bearing box when starting a
turbine.
Citation List
20 Patent Literature
[0004] Patent Document 1: JP2012-62872A
SUMMARY
Problems to be Solved
25 [0005] In recent years, in order to reduce the cost and improve the performance of a steam
turbine, the axial length of the turbine tends to be shortened, and in line with this, a bearing box
for accommodating a bearing which supports the turbine rotor also tends to be shortened in the
axial direction. As a result, a space inside or in the vicinity of the bearing box becomes narrow,
2
making it difficult to easily install an expansion member (hydraulic jack, etc.) during
maintenance, which may reduce the maintenance performance.
[0006] In view of the above, an object of at least one embodiment of the present invention
is to provide a maintenance method for a steam turbine and a steam turbine whereby it is
possible to suppress the reduction in maintenance 5 performance due to the shortening of the
steam turbine.
Solution to the Problems
[0007] A maintenance method for a steam turbine according to at least one embodiment of
10 the present invention is a maintenance method for a steam turbine including a rotor, a casing
for accommodating the rotor, and a bearing box for accommodating a bearing which supports
the rotor, comprising: a step of installing an expansion-and-contraction member below the rotor
by using an upward facing flat surface disposed between the casing and the bearing box in an
axial direction; and a step of pushing up the rotor upward by the expansion-and-contraction
15 member.
[0008] Further, a steam turbine according to at least one embodiment of the present
invention comprises: a rotor; a casing for accommodating the rotor; a bearing box for
accommodating a bearing which supports the rotor; and a protruding portion protruding from
the bearing box toward the casing in an axial direction and capable of being fitted into the casing
20 below the rotor. The protruding portion has an upper surface which is an upward facing flat
surface disposed between the casing and the bearing box in the axial direction below the rotor.
Advantageous Effects
[0009] At least one embodiment of the present invention provides a maintenance method
25 for a steam turbine and a steam turbine whereby it is possible to suppress the reduction in
maintenance performance due to the shortening of the steam turbine.
BRIEF DESCRIPTION OF DRAWINGS
3
[0010] FIG. 1 is a schematic diagram of a steam turbine according to an embodiment.
FIG. 2 is a schematic cross-sectional view of the steam turbine shown in FIG. 1 including
a bearing box.
FIG. 3A is a partial cross-sectional view of the steam turbine including cross-section A-A
5 of FIG. 2.
FIG. 3B is a cross-sectional view taken along line B-B of FIG. 3A.
FIG. 4 is a flowchart of a maintenance method according to an embodiment.
FIG. 5 is a diagram for describing the process of the maintenance method according to an
embodiment.
10 FIG. 6 is a diagram for describing the process of the maintenance method according to an
embodiment.
FIG. 7 is a cross-sectional view taken along line C-C of FIG. 6.
DETAILED DESCRIPTION
15 [0011] Embodiments of the present invention will now be described in detail with reference
to the accompanying drawings. It is intended, however, that unless particularly identified,
dimensions, materials, shapes, relative positions, and the like of components described in the
embodiments shall be interpreted as illustrative only and not intended to limit the scope of the
present invention.
20 [0012] (Configuration of steam turbine)
FIG. 1 is a schematic diagram of a steam turbine according to an embodiment. FIG. 2
is a schematic cross-sectional view of the steam turbine shown in FIG. 1 including a bearing
box. FIG. 3A is a partial cross-sectional view of the steam turbine including cross-section AA
of FIG. 2. FIG. 3B is a cross-sectional view taken along line B-B of FIG. 3A.
25 [0013] As shown in FIGs. 1 and 2, the steam turbine 1 according to an embodiment includes
a rotor 5 (see FIG. 2) which is rotatable around the central axis O, a casing 2 disposed so as to
cover the rotor 5, a bearing 6 (see FIG. 2) which supports the rotor 5 in a rotatable manner, and
a bearing box 10 for accommodating the bearing 6. As shown in FIG. 2, the rotor 5 is disposed
4
so as to penetrate the casing 2 and the bearing box 10. A steam passage is provided in the
casing 2. The casing 2 accommodates a plurality of blades (not shown) disposed in the steam
passage around the rotor 5.
[0014] The casing 2 includes a casing upper half part 2A located on the upper side and a
casing lower half part 2B located on the lower side 5 in the upper-lower direction (vertical
direction), and an upper flange portion 3A provided on the casing upper half part 2A and a lower
flange portion 3B provided on the casing lower half part 2B are secured by a bolt (not shown).
[0015] The casing 2 is supported by a casing support portion 8 fixed to a base 7. In the
illustrated embodiment, the casing lower half part 2B has curved leg portions 4 protruding in
10 the axial direction (the direction of the central axis O of the rotor), and is supported by the
casing support portion 8 via the curved leg portions 4. In the casing 2 shown in FIG. 1, the
casing lower half part 2B has a pair of curved leg portions 4 on both sides of the central axis O
in plan view at each of the two axial end portions, i.e., four curved leg portions 4 in total.
[0016] The bearing box 10 includes a bearing box upper half part 10A located on the upper
15 side and a bearing box lower half part 10B located on the lower side in the upper-lower direction,
and the bearing box upper half part 10A and the bearing box lower half part 10B are secured by
a bolt (not shown) or the like. The bearing box 10 is installed on the base 7. The bearing
box 10 may include a bearing stand portion 46 for supporting the bearing 6 and a seal mounting
portion 48 to which a seal member 24, which will be described later, is mounted. The bearing
20 stand portion 46 is disposed so as to at least partially overlap the bearing 6 in the axial direction,
and has axial end surfaces 47a and 47b.
[0017] As shown in FIG. 2, a seal member 24 is disposed in a penetration portion 11 of the
bearing box 10 through which the rotor 5 penetrates to suppress leakage of a fluid (e.g., oil)
from the inside of the bearing box 10 to the external space. In an embodiment, the seal
25 member 24 includes a ring member 25 disposed so as to surround the rotor 5 on the radially
outer side of the rotor 5, and a fin portion 27 disposed in a gap between the rotor 5 and the ring
member 25 in the radial direction. The ring member 25 has a plurality of bolt holes extending
along the axial direction, and the seal member 24 is mounted to the seal mounting portion 48
5
of the bearing box 10 by screwing bolts 26 into the bolt holes. The seal mounting portion 48
may be disposed so as to protrude from the casing-side axial end surface 47a of the axial end
surfaces 47a, 47b of the bearing stand portion 46 toward the casing 2 in the axial direction.
Further, the seal mounting portion 48 may be adjacent to the seal member 24 in the axial
5 direction.
[0018] The seal member 24 may have a structure that can be divided into an upper half part
and a lower half part. The seal member 24 shown in FIG. 2 includes a seal member upper half
part 24A located on the upper side and a seal member lower half part 24B located on the lower
side in the upper-lower direction, and has a structure that can be divided into the upper half part
10 and the lower half part.
[0019] As shown in FIGs. 1 and 2, the steam turbine 1 includes a protruding portion 16
protruding from the bearing box 10 toward the casing 2 in the axial direction and capable of
being fitted into the casing 2 below the rotor 5. The protruding portion 16 is disposed so as to
protrude in the axial direction from a portion where the bearing box 10 and the base 7 to which
15 the bearing box 10 is fixed face each other in the upper-lower direction. In the illustrated
embodiment, the protruding portion 16 is disposed so as to protrude in the axial direction from
the bearing box lower half part 10B.
[0020] Further, the casing 2 of the steam turbine 1 has a groove portion 15 capable of
engaging with the protruding portion 16 below the rotor. In the illustrated embodiment, the
20 groove portion 15 is provided in a receiving portion 14 disposed so as to protrude from the
casing lower half part 2B toward the bearing box 10 in the axial direction. By fitting the
protruding portion 16 to the groove portion 15, a fitting portion 13 is formed.
[0021] As shown in FIGs. 3A and 3B, when the protruding portion 16 of the bearing box
10 and the groove portion 15 of the casing 2 are fitted together, a gap is formed between a tip
25 surface 16a of the protruding portion 16 and a bottom surface 15a of the groove portion 15,
which allows the casing 2 to move relative to the bearing box 10 in the axial direction due to
thermal expansion or the like. Further, as shown in FIG. 3A, in plan view, there is almost no
gap in the direction perpendicular to the central axis of the rotor 5 between the protruding
6
portion 16 and the groove portion 15, which restricts movement of the casing 2 relative to the
bearing box 10 in this direction. Therefore, by fitting the protruding portion 16 to the groove
portion 15, it is possible to align the centers of the bearing box 10 and the casing 2 while
allowing movement of the casing 2 relative to the bearing box 10 in the axial direction. The
straight line O’ in FIG. 3A indicates the position of the central 5 axis O of the rotor 5 in plan view.
[0022] In the exemplary embodiment shown in FIGs. 2 to 3B, the protruding portion 16
protruding from the bearing box 10 in the axial direction includes a base portion 18 connected
to the bearing box 10, and a tip portion 20 disposed closer to the casing 2 than the base portion
18. The base portion 18 has an upper surface 19 disposed above an upper surface 21 of the
10 tip portion 20. The tip portion 20 is at least partially disposed below the upper surface of the
base 7 on which the bearing box 10 is installed.
[0023] When the bearing box 10 is shortened in the axial direction with the shortening of
the steam turbine 1, the bearing box 10 may also be shortened in the upper-lower direction to
prevent the bearing box 10 from overturning. In this case, it is necessary to provide the upper
15 surface of the base 7 at a higher position than conventional. On the other hand, since the
structure of the casing 2 remains unchanged, the position of the groove portion 15 of the casing
2, which engages with the protruding portion 16 of the bearing box 10, is unchanged, so the
fitting position between the groove portion 15 and the protruding portion 16 is unchanged.
Accordingly, the protruding portion 16 is fitted to the groove portion 15 at a position lower than
20 the mounting position of the bearing box 10 to the base 7. Thus, in the steam turbine 1 that is
shortened in the axial direction, as described above, in order to allow the protruding portion 16
and the groove portion 15 to be appropriately fitted together, the protruding portion 16 has the
base portion 18 connected to the casing 2 and the tip portion 20 at least partially disposed below
the upper surface of the base 7. Further, the tip portion 20 is at least partially disposed below
25 the bottom surface of the bearing box 10. Here, the base 7 refers to the foundation on which
the bearing box 10 is installed, and the bearing box 10 is installed on the upper surface of the
base 7.
[0024] The steam turbine 1 has an upward facing flat surface 12 disposed between the
7
casing 2 and the bearing box 10 below the rotor 5. As described below, during maintenance
of the steam turbine 1, an expansion-and-contraction member (e.g., hydraulic jack) for pushing
up the rotor 5 is installed by using the flat surface 12. That is, the flat surface 12 is configured
such that the expansion-and-contraction member can be placed thereon.
[0025] In some embodiments, the flat surface 5 12 may be formed by the upper surface of
the protruding portion 16 protruding from the bearing box 10 toward the casing 2 in the axial
direction below the rotor 5. In the exemplary embodiment shown in FIGs. 2 and 3, the upper
surface 19 of the base portion 18 of the protruding portion 16 functions as the flat surface 12.
In the protruding portion 16, the vertical dimension of the portion with the flat surface 12
10 of the base portion 18 is larger than the vertical dimension of the tip portion 20. Further, the
vertical dimension of the portion with the flat surface 12 of the base portion 18 is larger than
the vertical dimension of the portion closer to the bearing box 10 than the portion with the flat
surface 12 of the base portion 18.
[0026] The flat surface 12 may be located below the seal member 24 disposed in the bearing
15 box 10, as shown in FIG. 2, for example. In this case, during maintenance, the space formed
by removing the seal member 24 can be used to install the expansion-and-contraction member.
[0027] Further, for example as shown in FIG. 2, the flat surface 12 may be disposed closer
to the bearing box 10 in the axial direction than the fitting portion 13 of the protruding portion
16 to the groove portion 15 of the receiving portion 14 (casing 2). In this case, it becomes
20 easier to avoid interference between the casing 10 and the expansion-and-contraction member
placed on the flat surface 12 during maintenance.
[0028] Further, for example as shown in FIG. 2, the seal mounting portion 48 protruding
from the bearing stand portion 46 of the bearing box 10 in the axial direction may be disposed
between the rotor 5 and the flat surface 12 in the vertical direction (upper-lower direction), and
25 may be adjacent to the seal member 24 in the axial direction. In this case, since a space is
formed in the radially outer region of the seal member 24 and the seal mounting portion 48,
when the seal member 24 is removed during maintenance, this space can be used to easily install
the expansion-and-contraction member.
8
[0029] Further, the flat surface 12 may have a recessed portion or a projecting portion
capable of engaging with a jig (described later) on which the expansion-and-contraction
member can be placed. In this case, the jig can be appropriately installed on the flat surface
12 in a relatively narrow space. In the exemplary embodiment shown in FIGs. 2 to 3B, the
upper sur 5 face 19 of the base portion 18 of the protruding portion 16 as the flat surface 12 has a
recessed portion 22 that is recessed downward. This recessed portion can engage with a
projecting portion provided in the jig.
[0030] (Maintenance method for steam turbine)
A maintenance method for a steam turbine according to some embodiments will be
10 described in accordance with the flowchart shown in FIG. 4. Here, the above-described steam
turbine 1 will be described as an example of the maintenance target. FIG. 4 is a flowchart of
a maintenance method according to an embodiment. FIGs. 5 and 6 are each a diagram for
describing the process of the maintenance method according to an embodiment, and are a
schematic cross-sectional view of the steam turbine including the bearing box similar to FIG.
15 2. FIG. 7 is a cross-sectional view taken along line C-C of FIG. 6.
[0031] In the maintenance method according to an embodiment, first, the bearing box upper
half part 10A (see FIG. 2) is removed by removing the bolt securing the bearing box upper half
part 10A and the bearing box lower half part 10B (step S102). Further, the seal member 24 is
removed by removing the bolt 26 (step S104). Further, the casing upper half part 2A is
20 removed. As a result, as shown in FIG. 5, the upper half of the steam turbine 1 is opened, and
the rotor 5 can be lifted.
[0032] Step S102 and step S104 may be performed sequentially or at least partially
simultaneously. For example, the seal member upper half part 24A may be removed at the
same time as the bearing box upper half part 10A is removed, and then the seal member lower
25 half part 24B may be removed.
[0033] Then, as shown in FIGs. 6 and 7, an annular member 36 facing the lower region of
the outer peripheral surface 5a of the rotor 5 is installed (step S106). When the rotor 5 is
pushed up in the subsequent step, applying the push-up force from the expansion-and-
9
contraction member to the rotor 5 via the annular member 36 makes it easier to push up the
rotor 5 appropriately. In step S106, the annular member 36 may be installed such that at least
a portion of the annular member 36 is disposed in the space S1 (see FIG. 5) formed by removing
the seal member 24 (see FIG. 2) in step S104. If the rotor 5 is lifted without the annular
5 member 36, the execution of step S106 may be skipped.
[0034] Then, as shown in FIGs. 6 and 7, a hydraulic jack (expansion-and-contraction
member) 30 is installed below the rotor 5 by using the upward facing flat surface 12 disposed
between the casing 2 and the bearing box 10 in the axial direction (step S108).
[0035] In step S108, the hydraulic jack 30 may be installed such that at least a portion of
10 the hydraulic jack 30 is disposed in the space S1 (see FIG. 5) formed by removing the seal
member 24 (see FIG. 2) in step S104.
[0036] As shown in FIGs. 6 and 7, the flat surface 12 may be the upper surface 19 of the
base portion 18 of the protruding portion 16 protruding from the bearing box 10 toward the
casing 2 in the axial direction. That is, in step S108, the hydraulic jack 30 may be installed by
15 using the upper surface 19 of the base portion 18 which is the flat surface 12.
[0037] In step S108, for example, as shown in FIGs. 6 and 7, a jig 32 on which the hydraulic
jack 30 can be placed may be installed on the flat surface 12, and the hydraulic jack 30 may be
installed on the upper surface 33 of the jig 32. The jig 32 is configured to have an upper
surface 33 at a height suitable for mounting the hydraulic jack 30.
20 [0038] As shown in FIGs. 6 and 7, the flat surface 12 has a recessed portion 22 that is
recessed downward (or a projecting portion that protrudes upward), and the lower end portion
of the jig 32 has a projecting portion 34 that protrudes downward (or a recessed portion that is
recessed upward). The jig 32 may be installed on the flat surface 12 by engaging the recessed
portion 22 (or the projecting portion) of the flat surface 12 with the projecting portion 34 (or
25 the recessed portion) of the jig 32.
[0039] Although not shown, in step S108, the hydraulic jack 30 may be installed on the flat
surface 12 (e.g., the upper surface 19 of the base portion 18 of the protruding portion 16).
[0040] Then, the push-up force of the hydraulic jack 30 is applied to the rotor by the
10
hydraulic jack 30 installed in step S108 to push up the rotor 5 (step S110). If the annular
member 36 has been installed in step S106, the push-up force from the expansion-andcontraction
member is applied to the rotor 5 via the annular member 36.
[0041] With the method according to the above-described embodiment, since the hydraulic
jack 30 (expansion-and-contraction member) 5 is installed below the rotor 5 by using the flat
surface 12 disposed between the casing 2 and the bearing box 10 in the axial direction, for
example even if there is not sufficient installation space in the bearing box 10 or the like due to
the shortening of the turbine, the hydraulic jack 30 can be easily installed by using the flat
surface 12 during maintenance. Thus, even if the steam turbine 1 is shortened in the axial
10 direction, maintenance can be efficiently performed, and the reduction in maintenance
performance due to the shortening of the steam turbine 1 can be suppressed.
[0042] In step S110, the hydraulic jack 30 and the jack bolt 42 (see FIG. 7) may be used
together to lift the rotor 5 upward. In an embodiment, as shown in FIG. 7, an arm 38 having
a through hole 43 is attached to a member 44 (e.g., bearing box lower half part 10B) installed
15 or fixed to the base 7 by, for example, a bolt 40. The tip portion of the jack bolt 42 inserted in
the through hole 43 is screwed into a screw hole 37 provided in the upper surface of the annular
member 36. By screwing the jack bolt 42 into the screw hole 37, the rotor 5 and the annular
member 36 can be jacked up with respect to the casing lower half part 2B (casing 2).
[0043] By using the hydraulic jack 30 and the jack bolt 42 together in this manner, a larger
20 force can be applied to the rotor 5, and the rotor 5 can be lifted higher. Further, by pushing up
the rotor 5 with the hydraulic jack 30, the height of the rotor 5 can be adjusted with high
accuracy.
[0044] In the above-described embodiments, the case where the upper surface of the
protruding portion 16 protruding from the bearing box 10 in the axial direction is used as the
25 flat surface 12 for installation of the hydraulic jack 30 (expansion-and-contraction member) has
been described. However, in other embodiments, for example, an upward facing surface of a
beam disposed between the casing 2 and the bearing box 10 in the axial direction may be used
as the flat surface 12 for installation of the hydraulic jack 30. The beam may be disposed so
11
as to extend along the axial direction or along the direction perpendicular to the axial direction
in plan view.
[0045] The contents described in the above embodiments would be understood as follows,
for instance.
[0046] (1) A maintenance method for a steam 5 turbine according to at least one embodiment
of the present invention is a maintenance method for a steam turbine (1) including a rotor (5),
a casing (2) for accommodating the rotor, and a bearing box (10) for accommodating a bearing
(6) which supports the rotor, comprising: a step (e.g., the above-described step S108) of
installing an expansion-and-contraction member (e.g., the above-described hydraulic jack 30)
10 below the rotor by using an upward facing flat surface (12) disposed between the casing and
the bearing box in an axial direction; and a step (e.g., the above-described step S110) of pushing
up the rotor upward by the expansion-and-contraction member.
[0047] With the above method (1), since the expansion-and-contraction member is installed
below the rotor by using the flat surface disposed between the casing and the bearing box in the
15 axial direction, for example even if there is not sufficient installation space in the bearing box
or the like due to the shortening of the turbine, the expansion-and-contraction member can be
easily installed by using the flat surface during maintenance. Thus, with the above
configuration (1), even if the steam turbine is shortened in the axial direction, maintenance can
be efficiently performed, and the reduction in maintenance performance due to the shortening
20 of the steam turbine can be suppressed.
[0048] (2) In some embodiments, in the above method (1), the maintenance method
comprises a step (e.g., the above-described step S104) of removing, from the bearing box, a
seal member disposed in a penetration portion of the bearing box through which the rotor
penetrates. The step of installing the expansion-and-contraction member includes installing
25 the expansion-and-contraction member such that at least a portion of the expansion-andcontraction
member is disposed in a space (S1) formed by removing the seal member.
[0049] During maintenance of a bearing of a steam turbine, a seal member provided in a
bearing box is usually removed. In this regard, with the above method (2), since the
12
expansion-and-contraction member is installed by using the space formed by removing the seal
member disposed in the bearing box, the expansion-and-contraction member can be easily
installed without special work for providing an installation space during maintenance. Thus,
it is possible to suppress the reduction in maintenance performance due to the shortening of the
5 steam turbine.
[0050] (3) In some embodiments, in the above method (1) or (2), the pushing-up step
includes applying a push-up force from the expansion-and-contraction member to the rotor via
an annular member (36) disposed so as to face a lower region of an outer peripheral surface
(5a) of the rotor.
10 [0051] With the above method (3), since the push-up force from the expansion-andcontraction
member is applied to the rotor via the annular member disposed so as to face the
lower region of the outer peripheral surface of the rotor, the rotor can be pushed up by
appropriately applying the push-up force from the expansion-and-contraction member to the
rotor.
15 [0052] (4) In some embodiments, in any one of the above methods (1) to (3), the
maintenance method comprises a step of jacking up the rotor and the annular member with
respect to the casing by using a jack bolt (42) inserted in a through hole (43) provided in an arm
(38) attached to a base (7) or to a member (44) installed or fixed to a base.
[0053] With the above method (4), since the expansion-and-contraction member and the
20 jack bolt are used together for pushing up the rotor, the rotor can be pushed up more reliably.
[0054] (5) In some embodiments, in any one of the above methods (1) to (4), the steam
turbine includes a protruding portion (16) protruding from the bearing box toward the casing in
the axial direction and capable of being fitted into the casing below the rotor, and the flat surface
includes an upper surface of the protruding portion (e.g., the above-described upper surface 19
25 of the base portion 18 of the protruding portion 16).
[0055] Some steam turbines are provided with a protruding portion protruding in the axial
direction and capable of being fitted into the casing for alignment of the casing and the bearing
box. In this regard, with the above method (5), the expansion-and-contraction member can be
13
easily installed during maintenance by using the upper surface of the protruding portion
protruding from the bearing box toward the casing in the axial direction and capable of being
fitted into the casing below the rotor. Thus, it is possible to suppress the reduction in
maintenance performance due to the shortening of the steam turbine.
[0056] (6) In 5 some embodiments, in the above method (5), the step of installing the
expansion-and-contraction member includes installing the expansion-and-contraction member
on the upper surface of the protruding portion.
[0057] With the above method (6), since the expansion-and-contraction member is installed
on the upper surface of the protruding portion, the expansion-and-contraction member can be
10 easily installed during maintenance. Thus, it is possible to suppress the reduction in
maintenance performance due to the shortening of the steam turbine.
[0058] (7) In some embodiments, in the above method (5), the maintenance method
comprises a step of installing a jig (32) on which the expansion-and-contraction member can
be placed on the upper surface of the protruding portion. The step of installing the expansion15
and-contraction member includes installing the expansion-and-contraction member on an upper
surface (33) of the jig.
[0059] With the above method (7), since the expansion-and-contraction member is installed
on the upper surface of the jig installed on the upper surface of the protruding portion, the
expansion-and-contraction member can be easily installed during maintenance. Thus, it is
20 possible to suppress the reduction in maintenance performance due to the shortening of the
steam turbine.
[0060] (8) In some embodiments, in the above method (7), the step of installing the jig
includes engaging a projecting portion or a recessed portion (e.g., the above-described
projecting portion 34) disposed in a lower portion of the jig with a recessed portion or a
25 projecting portion (e.g., the above-described recessed portion 22) disposed in the upper surface
of the protruding portion.
[0061] With the above method (8), by engaging the projecting portion or the recessed
portion disposed in the lower portion of the jig with the recessed portion or the projecting
14
portion disposed in the upper surface of the protruding portion, even if the installation space for
the jig is narrow, the jig can be installed easily and reliably. As a result, the expansion-andcontraction
member can be easily installed during maintenance. Thus, it is possible to
suppress the reduction in maintenance performance due to the shortening of the steam turbine.
[0062] (9) A steam turbine (1) according to at 5 least one embodiment of the present invention
comprises: a rotor (5); a casing (2) for accommodating the rotor; a bearing box (10) for
accommodating a bearing which supports the rotor; and a protruding portion (16) protruding
from the bearing box toward the casing in an axial direction and capable of being fitted into the
casing below the rotor. The protruding portion has an upper surface (e.g., the above-described
10 upper surface 19 of the base portion 18 of the protruding portion 16) which is an upward facing
flat surface (12) disposed between the casing and the bearing box in the axial direction below
the rotor. The flat surface is configured such that an expansion-and-contraction member (e.g.,
the above-described hydraulic jack) for pushing up the rotor can be placed thereon.
[0063] Some steam turbines are provided with a protruding portion protruding in the axial
15 direction and capable of being fitted into the casing for alignment of the casing and the bearing
box. In this regard, with the above configuration (9), the expansion-and-contraction member
can be easily installed during maintenance by using the upper surface of the protruding portion
protruding from the bearing box toward the casing in the axial direction and capable of being
fitted into the casing below the rotor. Thus, with the above configuration (9), even if the steam
20 turbine is shortened in the axial direction, maintenance can be efficiently performed, and the
reduction in maintenance performance due to the shortening of the steam turbine can be
suppressed.
[0064] (10) In some embodiments, in the above configuration (9), the steam turbine
comprises a seal member (24) disposed in a penetration portion of the bearing box through
25 which the rotor penetrates. The upper surface of the protruding portion is disposed below the
seal member.
[0065] During maintenance of a bearing of a steam turbine, a seal member provided in a
bearing box is usually removed. In this regard, with the above configuration (10), since the
15
expansion-and-contraction member can be installed by using the space formed by removing the
seal member disposed in the bearing box, the expansion-and-contraction member can be easily
installed without special work for providing an installation space during maintenance. Thus,
it is possible to suppress the reduction in maintenance performance due to the shortening of the
5 steam turbine.
[0066] (11) In some embodiments, in the above configuration (10), the bearing box
includes: a bearing stand portion (46) for supporting the bearing; and a seal mounting portion
(48) disposed between the rotor and the flat surface in a vertical direction, protruding from an
axial end surface (47a) of the bearing stand portion toward the casing in the axial direction, and
10 provided with the seal member.
[0067] With the above configuration (11), since the seal member is disposed in the bearing
box seal mounting portion, a space is formed in a radially outer region of the seal member.
Thus, when the seal member is removed during maintenance, this space can be used to easily
install the expansion-and-contraction member. Thus, it is possible to suppress the reduction
15 in maintenance performance due to the shortening of the steam turbine.
[0068] (12) In some embodiments, in any one of the above configurations (9) to (11), the
upper surface of the protruding portion has a recessed portion or a projecting portion (e.g., the
above-described recessed portion 22) capable of engaging with a jig (32) on which an
expansion-and-contraction member for pushing up the rotor can be placed.
20 [0069] With the above configuration (12), since the expansion-and-contraction member can
be installed on the upper surface of the jig installed on the upper surface of the protruding
portion, the expansion-and-contraction member can be easily installed during maintenance.
Further, by engaging the recessed portion or projecting portion disposed in the upper surface of
the protruding portion with the jig, even if the installation space for the jig is narrow, the jig can
25 be installed easily and reliably. Thus, it is possible to suppress the reduction in maintenance
performance due to the shortening of the steam turbine.
[0070] (13) In some embodiments, in any one of the above configurations (9) to (12), the
protruding portion includes: a base portion (18) connected to the bearing box; and a tip portion
16
(20) disposed closer to the casing than the base portion. The base portion has an upper surface
(19) as the flat surface, and the upper surface of the base portion is disposed above an upper
surface (21) of the tip portion.
[0071] With the above configuration (13), the expansion-and-contraction member can be
easily installed during maintenance by using the 5 upper surface of the base portion of the
protruding portion connected to the bearing box. Thus, with the above configuration (13),
even if the steam turbine is shortened in the axial direction, maintenance can be efficiently
performed, and the reduction in maintenance performance due to the shortening of the steam
turbine can be suppressed.
10 [0072] (14) In some embodiments, in any one of the above configurations (9) to (13), the
flat surface is disposed closer to the bearing box in the axial direction than a fitting portion (13)
of the protruding portion to the casing.
[0073] With the above configuration (14), since the flat surface on which the expansionand-
contraction member can be placed is disposed closer to the bearing box than the fitting
15 portion of the protruding portion to the casing, it becomes easier to avoid interference between
the casing and the expansion-and-contraction member placed on the flat surface during
maintenance.
[0074] Embodiments of the present invention were described in detail above, but the
present invention is not limited thereto, and various amendments and modifications may be
20 implemented.
[0075] Further, in the present specification, an expression of relative or absolute
arrangement such as “in a direction”, “along a direction”, “parallel”, “orthogonal”, “centered”,
“concentric” and “coaxial” shall not be construed as indicating only the arrangement in a strict
literal sense, but also includes a state where the arrangement is relatively displaced by a
25 tolerance, or by an angle or a distance whereby it is possible to achieve the same function.
For instance, an expression of an equal state such as “same” “equal” and “uniform” shall
not be construed as indicating only the state in which the feature is strictly equal, but also
includes a state in which there is a tolerance or a difference that can still achieve the same
17
function.
Further, an expression of a shape such as a rectangular shape or a cylindrical shape shall
not be construed as only the geometrically strict shape, but also includes a shape with
unevenness or chamfered corners within the range in which the same effect can be achieved.
On the other hand, an expression such as “5 comprise”, “include”, and “have” are not
intended to be exclusive of other components.
Reference Signs List
[0076]
10 1 Steam turbine
2 Casing
2A Casing upper half part
2B Casing lower half part
3A Upper flange portion
15 3B Lower flange portion
4 Curved leg portion
5 Rotor
5a Outer peripheral surface
6 Bearing
20 7 Base
8 Casing support portion
10 Bearing box
10A Bearing box upper half part
10B Bearing box lower half part
25 11 Penetration portion
12 Flat surface
13 Fitting portion
14 Receiving portion
18
15 Groove portion
15a Bottom surface
16 Protruding portion
16a Tip surface
5 18 Base portion
19 Upper surface
20 Tip portion
21 Upper surface
22 Recessed portion
10 24 Seal member
24A Seal member upper half part
24B Seal member lower half part
25 Ring member
26 Bolt
15 27 Fin portion
30 Hydraulic jack
32 Jig
33 Upper surface
34 Projecting portion
20 36 Annular member
37 Screw hole
38 Arm
40 Bolt
42 Jack bolt
25 43 Through hole
44 Member
46 Bearing stand portion
47a, 47b Axial end surface
19
48 Seal mounting portion
O Central axis
S1 Space

I/We Claim:
1. A maintenance method for a steam turbine including a rotor, a casing for accommodating
the rotor, and a bearing box for accommodating a bearing which supports the rotor, the
5 maintenance method comprising:
a step of installing an expansion-and-contraction member below the rotor by using an
upward facing flat surface disposed between the casing and the bearing box in an axial
direction; and
a step of pushing up the rotor upward by the expansion-and-contraction member.
10
2. The maintenance method for a steam turbine according to claim 1, comprising a step of
removing, from the bearing box, a seal member disposed in a penetration portion of the bearing
box through which the rotor penetrates,
wherein the step of installing the expansion-and-contraction member includes installing
15 the expansion-and-contraction member such that at least a portion of the expansion-andcontraction
member is disposed in a space formed by removing the seal member.
3. The maintenance method for a steam turbine according to claim 1 or 2,
wherein the pushing-up step includes applying a push-up force from the expansion-and20
contraction member to the rotor via an annular member disposed so as to face a lower region
of an outer peripheral surface of the rotor.
4. The maintenance method for a steam turbine according to any one of claims 1 to 3,
comprising a step of jacking up the rotor and the annular member with respect to the casing by
25 using a jack bolt inserted in a through hole provided in an arm attached to a base or to a member
installed or fixed to a base.
5. The maintenance method for a steam turbine according to any one of claims 1 to 4,
21
wherein the steam turbine includes a protruding portion protruding from the bearing box
toward the casing in the axial direction and capable of being fitted into the casing below the
rotor, and
wherein the flat surface includes an upper surface of the protruding portion.
5
6. The maintenance method for a steam turbine according to claim 5,
wherein the step of installing the expansion-and-contraction member includes installing
the expansion-and-contraction member on the upper surface of the protruding portion.
7. The maintenance method for a steam 10 turbine according to claim 5, comprising a step of
installing a jig on which the expansion-and-contraction member can be placed on the upper
surface of the protruding portion,
wherein the step of installing the expansion-and-contraction member includes installing
the expansion-and-contraction member on an upper surface of the jig.
15
8. The maintenance method for a steam turbine according to claim 7,
wherein the step of installing the jig includes engaging a projecting portion or a recessed
portion disposed in a lower portion of the jig with a recessed portion or a projecting portion
disposed in the upper surface of the protruding portion.
20
9. A steam turbine, comprising:
a rotor;
a casing for accommodating the rotor;
a bearing box for accommodating a bearing which supports the rotor; and
25 a protruding portion protruding from the bearing box toward the casing in an axial
direction and capable of being fitted into the casing below the rotor,
wherein the protruding portion has an upper surface which is an upward facing flat surface
disposed between the casing and the bearing box in the axial direction below the rotor, and
22
wherein the flat surface is configured such that an expansion-and-contraction member for
pushing up the rotor can be placed thereon.
10. The steam turbine according to claim 9, comprising a seal member disposed in a
penetration por 5 tion of the bearing box through which the rotor penetrates,
wherein the upper surface of the protruding portion is disposed below the seal member.
11. The steam turbine according to claim 10,
wherein the bearing box includes:
10 a bearing stand portion for supporting the bearing; and
a seal mounting portion disposed between the rotor and the flat surface in a vertical
direction, protruding from an axial end surface of the bearing stand portion toward the casing
in the axial direction, and provided with the seal member.
15 12. The steam turbine according to any one of claims 9 to 11,
wherein the upper surface of the protruding portion has a recessed portion or a projecting
portion capable of engaging with a jig on which an expansion-and-contraction member for
pushing up the rotor can be placed.
20 13. The steam turbine according to any one of claims 9 to 12,
wherein the protruding portion includes:
a base portion connected to the bearing box; and
a tip portion disposed closer to the casing than the base portion,
wherein the base portion has an upper surface as the flat surface, and
25 wherein the upper surface of the base portion is disposed above an upper surface of the
tip portion.
14. The steam turbine according to any one of claims 9 to 13,
23
wherein the flat surface is disposed closer to the bearing box in the axial direction than a
fitting portion of the protruding portion to the casing.