U.S. patent application number 12/746355 was filed with the patent office on 2010-10-14 for rotary machine.
This patent application is currently assigned to MITSUBISHI HEAVY INDUSTRIES, LTD.. Invention is credited to Toshihiro Inoue, Takaaki Matsuo, Shoki Yamashita.
Application Number | 20100260599 12/746355 |
Document ID | / |
Family ID | 41136028 |
Filed Date | 2010-10-14 |
United States Patent
Application |
20100260599 |
Kind Code |
A1 |
Yamashita; Shoki ; et
al. |
October 14, 2010 |
ROTARY MACHINE
Abstract
To reduce the size of a rotary machine and to provide a rotary
machine in which it is possible to achieve an improvement in
reliability and performance of the rotary machine. A first casing
(1) and a second casing (2) formed by dividing a substantially
cylindrical casing (101), enclosing in the interior thereof a rotor
shaft (4) in which rotor blades (11) are embedded, into two at
substantially a central portion relative to an axial direction of
the rotor shaft (4) are provided; a first coupling flange (1A) and
a second coupling flange (2A) are provided at openings in the first
casing (1) and the second casing (2), respectively; a third
coupling flange (3A) is provided, which is enclosed by the casing
(101), which is positioned at substantially a central portion of
the length in the axial direction in a substantially cylindrical
blade ring (3) holding stator blades (10) and enclosing the rotor
shaft (4), and which holds the blade ring (3); the first casing
(1), the second casing (2), and the blade ring (3) being assembled
by sandwiching the third coupling flange (3A) between the first
coupling flange (1A) and the second coupling flange (2A).
Inventors: |
Yamashita; Shoki; (Tokyo,
JP) ; Inoue; Toshihiro; (Tokyo, JP) ; Matsuo;
Takaaki; (Tokyo, JP) |
Correspondence
Address: |
WESTERMAN, HATTORI, DANIELS & ADRIAN, LLP
1250 CONNECTICUT AVENUE, NW, SUITE 700
WASHINGTON
DC
20036
US
|
Assignee: |
MITSUBISHI HEAVY INDUSTRIES,
LTD.
Tokyo
JP
|
Family ID: |
41136028 |
Appl. No.: |
12/746355 |
Filed: |
March 27, 2009 |
PCT Filed: |
March 27, 2009 |
PCT NO: |
PCT/JP2009/056929 |
371 Date: |
June 4, 2010 |
Current U.S.
Class: |
415/182.1 |
Current CPC
Class: |
F05D 2260/30 20130101;
F01D 25/243 20130101; F01D 25/26 20130101 |
Class at
Publication: |
415/182.1 |
International
Class: |
F04D 29/42 20060101
F04D029/42 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 31, 2008 |
JP |
2008-093753 |
Claims
1. A rotary machine, wherein a first casing and a second casing
formed by dividing a substantially cylindrical casing, enclosing in
the interior thereof a rotor shaft in which rotor blades are
embedded, into two at substantially a central portion relative to
an axial direction of the rotor shaft are provided; a first
coupling flange and a second coupling flange are provided at
openings in the first casing and the second casing, respectively; a
third coupling flange is provided, which is enclosed by the casing,
which is positioned at substantially a central portion of the
length in the axial direction in a substantially cylindrical blade
ring holding stator blades and enclosing the rotor shaft, and which
holds the blade ring; the first casing, the second casing, and the
blade ring being assembled by sandwiching the third coupling flange
between the first coupling flange and the second coupling
flange.
2. A rotary machine according to claim 1, wherein the blade ring is
held relative to the third coupling flange by a substantially
conical joining member, and an inner peripheral surface at the
blade ring side of the joining member projects from a high-pressure
side to a low-pressure side in a working fluid flowing between the
rotor blades and the stator blades.
3. A rotary machine according to claim 1, wherein an outer
peripheral portion of the third coupling flange is contained
between the first coupling flange and the second coupling
flange.
4. A rotary machine according to claim 1, wherein a pressure vessel
accommodating the casing therein is provided outside the casing,
and a fluid with a pressure higher than the working fluid flowing
between the rotor blades and the stator blades is filled in a space
between the casing and the pressure vessel.
Description
TECHNICAL FIELD
[0001] The present invention relates to a rotary machine used for a
steam turbine, a gas turbine, or the like.
BACKGROUND ART
[0002] Generally, a casing used for a steam turbine or a gas
turbine is divided into two, i.e., an upper casing and a lower
casing in which a rotor shaft is incorporated, and these casings
are coupled to each other on a horizontal surface using a bolt (see
Patent Japanese Unexamined Utility Model Application, Publication
No. S60-195908, for example).
[0003] Alternatively, in a turbine so-called "pot-like turbine",
the casing is integrally formed as one piece, a rotor shaft portion
is inserted from one end opening of the casing, and the end opening
is hermetically closed by fastening a screw ring which is engaged
with a screw portion provided on an inner periphery of the casing
(see Patent Japanese Unexamined Patent Application, Publication No.
S59-213907, for example).
[0004] It is an object of the casing structure described above is
to secure rigidity of the entire apparatus with respect to working
fluid having high temperature and high pressure, and to prevent
leak of the working fluid.
[0005] In the casing structure in which the casing is divided into
two on the horizontal surface as described above, the upper casing
and the lower casing are provided on entire peripheries of the
horizontal surfaces thereof with joining flanges, which project
from the entire periphery of the horizontal surface of the casing
and thus there is a problem that the joined casing itself is
increased in size.
[0006] Further, when the casing is increased in size, there is a
problem that the mass of the entire turbine is increased, and costs
for the material cost and production are increased.
[0007] If the working fluid leaks from the joining surface between
the upper casing and the lower casing, there is a concern that
performance of the turbine is affected. However, when the casing is
divided into two on the horizontal surface, the joining surface
extends over the entire periphery of the horizontal surface of the
casing, and thus there is a problem that a range is increased from
which the working fluid leaks. In the above-described structure,
since a penetrating portion of the rotor shaft is located on the
joining surface of the casing, there is a problem that the working
fluid leaks easier.
[0008] In the pot-like casing structure, it can be considered that
the range from which the working fluid leaks can be reduced as
compared with a case where the casing is provided on the entire
periphery with the joining flanges. However, the above structure in
which the casing is hermetically closed can be employed only to a
relatively small turbine, and such a structure must be replaced
with a structure provided with flanges in a large turbine. In this
case, there are problems that the flange and the joining bolt
project in the axial direction, the entire length of the casing is
increased, and the entire rotary machine is increased in size.
[0009] For example, in a turbine using a working fluid including a
certain material that must be carefully handled, it is not allowed
to leak the working fluid to atmosphere. Thus, a pressure vessel
(outer casing) which further covers the casing is provided, a clean
fluid which is not contaminated by the certain material is charged
under higher pressure than the working fluid in a space between the
pressure vessel and the casing, thereby preventing the fluid in the
casing from leaking outside (see FIG. 5).
[0010] FIG. 5 shows a configuration in which a casing 101 of the
turbine body described above is accommodated in a pressure vessel
(outer casing) 200. Constituent parts of the turbine are
accommodated in the casing 101 (not shown). A rotor shaft 4
penetrates the casing 101 and the pressure vessel 200. A clean
fluid which has pressure higher than the working fluid in the
turbine and which is not contaminated by a certain material is
charged in a space 201 between the casing 101 and the pressure
vessel 200 so as to prevent the fluid in the casing 101 from
leaking outside. However, in the above-described configuration,
because of increase in size of the casing 101, the pressure vessel
200 is also increased in size.
[0011] When the interior of the above turbine is contaminated with
a certain material, the turbine cannot be opened and inspected on a
site in its installed state for safety reasons unlike a general gas
turbine or a steam turbine. Therefore, it is necessary to open and
inspect the turbine after moving each turbine casing from the
turbine room to a special maintenance area. In such a case, there
are problems that, because of increase in size of the casing, it is
difficult to secure rigidity of the room, and a crane capacity for
hoisting the casing is largely affected.
[0012] In the pot-like casing structure described above, a blade
ring which holds turbine stator blades is mainly supported at the
end opening. However, in this state, the blade ring is supported in
a cantilever manner. Especially in a large turbine, when the blade
ring is supported in a cantilever manner, an overhang of the blade
ring is made longer and thus, there are problems that a center is
not sufficiently be held, and influence of a difference in thermal
extension in the axial direction between a rotating portion and a
stationary portion is increased.
DISCLOSURE OF INVENTION
[0013] The present invention has been accomplished to solve the
above problems, and it is an object of the present invention to
provide a rotary machine which can be reduced in size and which can
enhance reliability and performance.
[0014] In order to achieve the above object, the present invention
provides the following means.
[0015] In a casing structure of a turbine according to an aspect of
the present invention, a first casing and a second casing formed by
dividing a substantially cylindrical casing, enclosing in the
interior thereof a rotor shaft in which rotor blades are embedded,
into two at substantially a central portion relative to an axial
direction of the rotor shaft are provided; a first coupling flange
and a second coupling flange are provided at openings in the first
casing and the second casing, respectively; a third coupling flange
is provided, which is enclosed by the casing, which is positioned
at substantially a central portion of the length in the axial
direction in a substantially cylindrical blade ring holding stator
blades and enclosing the rotor shaft, and which holds the blade
ring; the first casing, the second casing, and the blade ring being
assembled by sandwiching the third coupling flange between the
first coupling flange and the second coupling flange.
[0016] According to the above aspect, the casing is divided into
two in the axial direction, for example on a division surface
intersecting with the rotor shaft, and the casing can be reduced in
size as compared with a case where the casing is divided into two
on the horizontal surface, e.g., on a division surface extending
along the rotor shaft.
[0017] More specifically, when the casing is divided into two on
the horizontal surface, coupling flanges used for fastening the
divided casings to each other project outward from the entire
periphery of the casing. In a general steam turbine or a gas
turbine, a cross sectional area of a casing divided into two on
vertical surface perpendicular to the rotor shaft becomes smaller
than a horizontal cross section of a casing divided into two on the
horizontal surface. Therefore, in the casing which is divided into
two (first casing and second casing) in the axial direction, the
projecting range of the coupling flanges can be made smaller as
compared with the casing divided into two on the horizontal
surface. In this configuration, the casing can be reduced in
size.
[0018] According to the above aspect, the third coupling flange
which extends from the blade ring in a direction intersecting with
the axial direction, more preferably, in a substantially vertical
direction, is sandwiched between the first coupling flange of the
first casing and the second coupling flange of the second casing
which are divided in the axial direction, in assembling the first
casing, the second casing and the blade ring. In this
configuration, overhang of the blade ring can be reduced.
[0019] More specifically, by holding the blade ring with respect to
the casing via the third coupling flange located at substantially a
central portion of the blade ring in the axial direction, the
overhang of the blade ring can be reduced as compared with the
pot-like structure described in Japanese Unexamined Patent
Application, Publication No. S59-213907. In this configuration,
holding precision of the center of the blade ring with respect to
the rotor shaft is enhanced. Further, since the blade ring is
supported at substantially the central portion in the axial
direction, thermal extension of the blade ring in the axial
direction can equally be distributed.
[0020] In the above aspect, it is preferable that an inner
peripheral side of a connection member disposed between the blade
ring and the casing projects from the high-pressure side toward the
low-pressure side of the working fluid. In other words, it is
preferable that the joining member is a conical member which is
disposed between the blade ring and the third coupling flange, and
which inclines from the high-pressure side to the low-pressure side
of the working fluid flowing between the rotor blade and the stator
blade radially outward around the rotor shaft.
[0021] In this configuration, since the connection member functions
as an end plate of the pressure vessel, strength of the connection
member is enhanced.
[0022] According to the above aspect, the casing is divided into
two in the axial direction. Thus, leakage of the working fluid to
outside the casing and inflow of another fluid into the casing are
reduced as compared with a case where the casing is divided into
two on the horizontal surface. That is, there is no joining surface
of the flange in the penetrating portion of the rotor shaft,
leakage of the working fluid to outside the casing and inflow of
another fluid into the casing are reduced.
[0023] In the above aspect, an outer peripheral surface of the
third coupling flange sandwiched between the first and second
coupling flanges of the first and second casings divided in the
axial direction may be enclosed between the first and second
coupling flanges. In other words, the first coupling flange and the
second coupling flange may be directly joined to each other
radially outside around the rotor shaft, and the first coupling
flange and the second coupling flange may be joined radially inside
with the third coupling flange sandwiched therebetween.
[0024] In this configuration, only one flange coupling surface is
provided on the outer peripheral surface of the casing and the
range of the joining surface can be reduced. Therefore, leakage of
the working fluid to outside the casing and inflow of another fluid
into the casing are further reduced.
[0025] In the above aspect, it is preferable that a pressure vessel
accommodating the casing therein is provided outside the casing,
and a fluid with a pressure higher than the working fluid flowing
between the rotor blades and the stator blades is filled in a space
between the casing and the pressure vessel.
[0026] According to the above aspect, the working fluid is
prevented from flowing into the space between the casing and the
pressure vessel by charging a fluid having pressure higher than
that of the working fluid into the space. Therefore, the working
fluid is prevented from flowing outside the casing.
[0027] According to the rotary machine of the present invention,
the casing is divided into two in the axial direction, there are
effects that the casing and the pressure vessel (outer casing)
enclosing the casing therein can be reduced in size, leakage of the
working fluid to outside the casing and inflow of another fluid
into the casing are reduced, and reliability and performance of the
rotary machine are enhanced.
[0028] Further, holding precision of the center of the blade ring
with respect to the rotor shaft is enhanced, and reliability of the
rotary machine is enhanced.
BRIEF DESCRIPTION OF DRAWINGS
[0029] FIG. 1 is a schematic diagram for describing an entire
configuration of a gas turbine according to a first example of the
present invention.
[0030] FIG. 2A is a schematic plan view of an axial two
piece-configuration of a casing structure.
[0031] FIG. 2B is an axial schematic side view of the axial two
piece-configuration of the casing structure.
[0032] FIG. 3A is a schematic plan view of a horizontal two
piece-configuration of the casing structure.
[0033] FIG. 3B is an axial schematic side view of the horizontal
two piece-configuration of the casing structure.
[0034] FIG. 4 is a schematic diagram for describing an entire
configuration of a gas turbine according to a second example of the
present invention.
[0035] FIG. 5 is a schematic diagram for describing a configuration
in which a casing of a gas turbine is accommodated in a pressure
vessel.
BEST MODE FOR CARRYING OUT THE INVENTION
First Embodiment
[0036] A casing structure of a gas turbine and the gas turbine
having such a casing structure according to an embodiment of the
present invention will be described with reference to FIGS. 1 to
5.
[0037] FIG. 1 is a schematic diagram for describing an entire
configuration of the gas turbine according to a first example of
the present invention.
[0038] As shown in FIG. 1, a gas turbine (rotary machine) 100
includes a casing 101 constituting an outer shape of the gas
turbine 100, a blade ring 3 which holds turbine stator blades 10 on
an inner periphery thereof, a rotor shaft 4 in which turbine rotor
blades 11 are embedded, an inlet scroll portion 5 which supplies a
working fluid to a first stage of the turbine stator blades 10, and
a discharge scroll portion 6 into which the working fluid
discharged from a last stage of the turbine rotor blades 11
flows.
[0039] In the gas turbine 100, the working fluid is accelerated by
the turbine stator blades 10, the turbine rotor blades 11 are blown
with the accelerated working fluid, and thermal energy of the
working fluid is converted into mechanical rotation energy. The
rotor shaft 4 is rotated and power is thus taken out. There are
generally provided the plurality of turbine stator blades 10 and
turbine rotor blades 11.
[0040] As shown in FIG. 1, the casing 101 constitutes the outer
shape of the gas turbine 100. The blade ring 3, the rotor shaft 4,
the inlet scroll portion 5 and the discharge scroll portion 6 are
accommodated in the casing 101. The casing 101 is divided into two,
namely a high-pressure casing 1 (first casing) and a low-pressure
casing 2 (second casing), at substantially a central portion in a
direction along the rotor shaft 4.
[0041] The casings 1 and 2 are substantially cylindrical members
whose one ends thereof are closed. In other words, the casings 1
and 2 are bottomed cylindrical members, or so-called pot-like
members. Outer peripheral portions of the open ends of the casings
1 and 2 have flanges 1A and 2A, respectively. The open ends of the
casings 1 and 2 butt against each other, the casings 1 and 2 are
fastened to each other with a flange 3A of the later-described
blade ring 3 interposed between the flanges 1A and 2A.
[0042] A through hole 7 into which the rotor shaft 4 is inserted is
formed in closed ends of the casings 1 and 2. An opening 8 into
which a tube is inserted is provided in cylindrical surfaces of the
casings 1 and 2. The working fluid flows into or out of the
tube.
[0043] As shown in FIG. 1, the blade ring 3 surrounds the rotor
shaft 4 together with the casings 1 and 2, constitutes the gas
turbine 100 and supports the turbine stator blades 10.
[0044] The blade ring 3 includes a substantially cylindrical member
extending in the axial direction around a rotational axis L, the
flange 3A disposed on the outermost peripheral portion, and
substantially conical connection member 3B which holes the
substantially cylindrical blade ring member by the flange 3A, and
the flange 3A is sandwiched between the flanges 1A and 2A. The
turbine stator blades 10 are held on the inner periphery of the
blade ring 3. The flange 3A is located at substantially the center
of the axial length of the blade ring 3.
[0045] The turbine rotor blades 11 are embedded in the rotor shaft
4, and as shown in FIG. 1, the turbine rotor blade 11 is blown with
the working fluid accelerated by the turbine stator blades 10, so
that the rotor shaft 4 is rotated and driven around the rotational
axis L. Generally, the plurality of turbine stator blades 10 and
the plurality of turbine rotor blades 11 are alternately provided,
but a known configurations may be employed thereto with no special
limitation.
[0046] As shown in FIG. 1, the working fluid flows through the
inlet scroll portion 5 and the discharge scroll portion 6. The
inlet scroll portion 5 supplies the working fluid to the first
stage of the turbine stator blades 10, and the working fluid
discharged from the last stage of the turbine rotor blades 11 flows
into the discharge scroll portion 6.
[0047] Operation of the gas turbine 100 having the above-described
configuration will be described next.
[0048] As shown in FIG. 1, in a high-temperature gas furnace, the
working fluid heated to a high temperature flows into the inlet
scroll portion 5 of the gas turbine 100. The working fluid which
has flowed into the inlet scroll portion 5 flows into an annular
channel 31, and flows into a cylindrical channel 32 at
substantially a constant flow rate in the circumferential
direction. The working fluid which has flowed into the cylindrical
channel 32 is introduced toward the first stage of the turbine
stator blades 10.
[0049] As shown in FIG. 1, the turbine rotor blades 11 are rotated
and driven by the flowing working fluid, and a rotational driving
force extracted by the rotor blades 11 is transmitted to the rotor
shaft 4. The working fluid of which rotational driving force is
extracted by the turbine rotor blades 11 and of which temperature
is lowered is discharged from the last stage of the turbine rotor
blades 11.
[0050] The working fluid which was discharged from the last stage
of the turbine rotor blades 11 flows into the cylindrical channel
32 of the discharge scroll portion 6 as shown in FIG. 1, and flows
toward the annular channel 31. The working fluid which has flowed
into the annular channel 31 is discharged from the discharge scroll
portion 6, i.e., from the gas turbine 100, and is again introduced
into the high-temperature gas furnace through each system.
[0051] According to the above configuration, in a case where the
casing 101 is divided into two in the axial direction, the casing
101 can be reduced in size as compared with a casing which is
divided into two on a horizontal surface. More specifically, the
flanges 1A and 1B used for fastening the divided casings 1 and 2 to
each other project outward from the entire periphery of the casing
101. However, since the area of the cross section which is vertical
in the axial direction is smaller than that of a horizontal cross
section, a range of projections of the flanges can be made smaller
in the casing which is axially divided into two as compared with a
configuration in which the casing is divided into two on the
horizontal surface.
[0052] FIGS. 2A, 2B, 3A, and 3B schematically show the
above-described configuration.
[0053] FIGS. 2A and 2B show a casing structure of a gas turbine in
the axial two piece-configuration, and are respectively a plan view
and a side view as viewed from the axial direction. Hatched
portions 1A and 1B indicate connection flanges provided on the
casings 1 and 2 which are divided in the axial direction, and the
connection flanges project from the casings 1 and 2. The entire
length of the casing 101 is defined as L1, and the diameter of the
casing 101 is defined as D1. In a general gas turbine, L1 is
greater than D1. Here, when a cylindrical pressure vessel is
provided outside the casings 1 and 2, an outer shape of the
pressure vessel is shown with a chain double-dashed line 200, and
its length is defined as L2 and its diameter is defined as D2.
[0054] FIGS. 3A and 3B show a casing structure of a gas turbine in
which the casing is divided into two on a horizontal surface, and
are respectively a plan view and a side view as viewed from the
axial direction. Hatched portions 111A and 111B indicate connection
flanges provided respectively on a casing 111 located on the upper
side (upper casing) and a casing 112 located on the lower side
(lower casing) in the casing divided on the horizontal surface, and
the connection flanges project radially outward and axially outward
from the casing 111 and the casing 112 around the rotational axis
L. The entire length of the casing 101 is defined as L1, and a
diameter of the casing 101 is defined as D1. In the gas turbine
itself in the same shape, L1 and D1 of the case where the casing is
axially divided into two (configuration of the present embodiment)
and those of the case where the casing is divided into two on the
horizontal surface are the same. When the cylindrical pressure
vessel is provided outside the casing 111 and the casing 112, the
outer shape of the pressure vessel is shown with chain
double-dashed line 210, and its length is defined as L3 and its
diameter is defined as D3.
[0055] As apparent from the drawings, the region of the hatched
portion of the axial two piece-configuration (configuration of the
present embodiment) shown in FIGS. 2A and 2B is smaller than that
of the horizontal two piece-configuration (conventional
configuration) shown in FIGS. 3A and 3B. That is, the range of the
projections of the flanges is small.
[0056] Also in the case where the pressure vessel is provided
outside the casing 101, while the diameter D2 of the axial two
piece-configuration and the diameter D3 of the horizontal two
piece-configuration are equal to each other, the length L2 of the
axial two piece-configuration can be reduced relative to the length
L3 of the horizontal two piece-configuration by the width of
projections of the flanges.
[0057] In this configuration, the casing 101 can be reduced in
size, the material cost and producing cost can be reduced, and the
mass of the entire gas turbine 100 can be reduced. Therefore, it
becomes easy to move the gas turbine 100 for inspection or other
purposes, and maintainability is enhanced. When the pressure vessel
200 is provided outside the gas turbine 100, the gas turbine can be
also reduced in size, the material cost and producing cost can be
reduced, and a gas turbine room can be reduced in size. In a
general gas turbine, since the length L1 is longer than the
diameter D1 as described above, the axial two piece-configuration
results in reduction in size of the casing 101.
[0058] According to the above configuration, the casings 1 and 2
and the blade ring 3 are assembled by sandwiching the flange 3A of
the blade ring between the coupling flanges 1A and 2A of the
casings 1 and 2. Then, overhang of the blade ring 3 can be reduced.
More specifically, when the blade ring 3 is held at the
substantially central portion in the axial direction with respect
to the casing, the overhang of the blade ring 3 can be reduced as
compared with the pot-like structure. In this configuration,
precision of center hold of the blade ring 3 is enhanced with
respect to the rotor shaft 4. Further, since the blade ring 3 is
supported at substantially the central portion in the axial
direction, axial thermal extension of the blade ring 3 can be
equally distributed, and reliability of the gas turbine 100 is
enhanced.
[0059] According to the above configuration, the connection member
3B of the blade ring 3 functions as an end plate in the pressure
vessel. A region 12 surrounded by the casing 1 and the blade ring 3
is located on the inlet of the working fluid, and a region 13
surrounded by the casing 2 and the blade ring 3 is located on the
outlet of the working fluid. Therefore, a pressure in the region 12
is higher than a pressure in the region 13. Thus, when the inner
periphery of the connection member 3 in the radial direction
projects from the high-pressure region 12 to the low-pressure
region 13, resistance to pressure of the connection member 3B is
enhanced.
[0060] Although the connection member 3B is a substantially conical
member in the present embodiment, the connection member 3B may have
a curved surface as long as it functions as an end plate. In a case
where strength required to the connection member 3B is relatively
small due to a pressure difference between the regions 12 and 13,
the connection member 3B may be of a flat-plate, and the shape
thereof is not especially limited.
[0061] According to the above configuration, when the casing 101 is
divided into two in the axial direction, leakage of the working
fluid to outside and inflow caused by entrainment of another fluid
into the casing from outside can be reduced as compared with the
horizontal two piece-configuration. More specifically, since there
is no flange joining surface provided in the penetrating portion of
the rotor shaft, leakage of the working fluid to outside the casing
and inflow of another fluid into the casing are further
reduced.
[0062] According to the above configuration, by dividing the casing
101 into two in the axial direction, an internal pressure load
applied by the pressure of the working fluid to the coupling
flanges of the divided surface can be equalized and reduced as
compared with the casing is divided into two on the horizontal
surface.
[0063] When the casing is divided into two on the horizontal
surface, since a high pressure portion and a low pressure portion
exist in the casing as described above, the internal pressure load
applied to the coupling flanges is varied depending upon locations.
Therefore, it is necessary to take such variation into
consideration upon designing strength of a bolt for fastening
flanges or strength of the flanges itself. When the casing 101 is
divided into two in the axial direction, since a load applied to
the flanges 1A and 2A becomes constant in the circumferential
direction, it becomes easy to design the strengths of the flanges
and the fastening bolt. As schematically shown in FIGS. 2A, 2B, 3A,
and 3B, the internal pressure load applied to the flanges can also
be reduced.
[0064] In the axial two piece-configuration, a pressure receiving
area A1 of the flange joining portion is substantially calculated
by the following equation (1),
A1=.pi..times.D1/4 (1)
[0065] wherein, .pi. represents the circle ratio.
[0066] In the horizontal two piece-configuration, a pressure
receiving area A2 of the flange joining portion is substantially
calculated by the following equation (2).
A2=L1.times.D1 (2)
[0067] In this case, because of .pi..apprxeq.3.14 and L1>D1, it
can be found that A1 is smaller than A2 from the following equation
(3).
A1=.pi..times.D1.sup.2/4<D1.sup.2<L1.times.D1=A2 (3)
[0068] When the pressure applied to a division surface in the axial
two piece-configuration and the horizontal two piece-configuration
is obtained by averaging the pressure of the high pressure portion
and the pressure of the low pressure portion, which are equal to
each other, the internal pressure load applied to the flanges is
determined by the pressure receiving area. Thus, the inner pressure
load is lower in the axial two piece-configuration.
Second Embodiment
[0069] FIG. 4 is a schematic diagram for describing an entire
configuration of a gas turbine according to a second example of the
present invention. A basic configuration of the gas turbine of the
present example is the same as that of the first example, but a
holding structure of the third coupling flange is different from
that of the first example. In the present example, only the holding
structure of the third coupling flange will be described with
reference to FIG. 4, and description of other constituent elements
will not be repeated. The constituent elements same as those of the
first example are designated with the same symbols, and description
thereof will not be repeated.
[0070] In the second example, as shown in FIG. 4, an outer
peripheral surface of the flange 3A sandwiched between the flanges
1A and 1B of the casings 1 and 2 obtained by axially dividing into
two the casing 101 of a gas turbine 300 is incorporated between the
flanges 1A and 1B.
[0071] In the first example, the flange 3A is sandwiched between
the flanges 1A and 2A of the casings 1 and 2. Therefore, there are
provided two flange joining surfaces on the outer periphery of the
casing 101. On the other hand, according to the configuration of
the second example, since an outer peripheral portion 3C of the
flange 3A is incorporated between the flanges 1A and 2A, the
flanges 1A and 2A are directly joined to each other on the outer
periphery of the casing 101. In this configuration, the number of
joining locations is one, and the peripheral length of the joining
surface can be reduced to substantially half. Accordingly, leakage
of the working fluid to outside the casing and inflow of another
fluid into the casing are reduced.
[0072] According to the above-described configuration, the
peripheral length of the cross section of the flange joining
portion is shorter in the axial two piece-configuration with
respect to that of the horizontal two piece-configuration. When the
casing 101 is divided into two in the axial direction, the range of
the joining surface can be reduced as compared with the case where
the casing is divided into two on the horizontal surface.
Accordingly, leakage of the working fluid to outside the casing and
inflow of another fluid into the casing are reduced.
[0073] FIGS. 2A, 2B, 3A, and 3B schematically show the above
configuration.
[0074] As described also in the first example, FIGS. 2A and 2B show
the casing structure of the gas turbine of the axial two
piece-configuration, and are respectively a plan view and a side
view as viewed from the axial direction. The hatched portions 1A
and 1B indicate the connection flanges provided on the casings 1
and 2 which are divided into two in the axial direction. In a
general gas turbine, the length L1 of the casing 101 is longer than
the diameter D1. The peripheral length L10 of the cross section of
the flange joining portion is substantially calculated by the
following equation (4),
L10=.pi..times.D1 (4)
[0075] wherein, .pi. represents the circle ratio.
[0076] FIGS. 3A and 3B show the casing structure of the gas turbine
divided into two on the horizontal surface, and are respectively a
plan view and a side view as viewed from the axial direction. The
hatched portions 111A and 111B indicate the connection flanges
provided respectively on the casing 111 and the casing 112 divided
on the horizontal surface. Similarly, when the entire length of the
casing 101 is defined as L1 and the diameter of the casing is
defined as D1, a peripheral length L11 of the cross section of the
flange joining portion is substantially calculated by the following
equation (5).
L11=2.times.(L1+D1) (5)
[0077] Because of .pi..apprxeq.3.14 and L1>D1, it can be found
that L10 is smaller than L11 from the following equation (6).
L10=.pi..times.D1<2.times.(D1+D1)<2.times.(L1+D1)=L11 (6)
[0078] Accordingly, the peripheral length of the cross section of
the flange joining portion is shorter in the axial two
piece-configuration with respect to that in the horizontal two
piece-configuration. When the casing 101 is divided into two in the
axial direction, the range of the joining surface can be reduced as
compared with the case where the casing is divided into two on the
horizontal surface. Accordingly, leakage of the working fluid to
outside the casing and inflow of another fluid into the casing can
further be reduced, and thus, reliability of the gas turbine 300
can be enhanced.
[0079] The scope of the present invention is not limited to the
above embodiments, and the present invention can variously be
modified within a range not departing from the subject matter of
the invention.
[0080] For example, although the present invention is applied to
the axial-flow turbine in the above embodiments, the present
invention is not limited to the axial-flow turbine, but the present
invention can also be applied to other kinds of turbines such as a
centrifugal type turbine and a diagonal-flow turbine.
[0081] The present invention can also be applied to a general
rotary machine of a gas turbine of another type in which air is
used as a working fluid and combustion energy of fossil fuel is
used as a heat source, a steam turbine, a compressor, or a pump,
with no special limitations.
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