U.S. patent application number 10/156887 was filed with the patent office on 2003-12-04 for axial compressor and gas bleeding method to thrust balance disk thereof.
This patent application is currently assigned to MITSUBISHI HEAVY INDUSTRIES, LTD.. Invention is credited to Laurello, Vincent, Yuri, Masanori.
Application Number | 20030223855 10/156887 |
Document ID | / |
Family ID | 29549233 |
Filed Date | 2003-12-04 |
United States Patent
Application |
20030223855 |
Kind Code |
A1 |
Yuri, Masanori ; et
al. |
December 4, 2003 |
AXIAL COMPRESSOR AND GAS BLEEDING METHOD TO THRUST BALANCE DISK
THEREOF
Abstract
In order to provide an axial compressor, and a gas bleeding
method to the thrust balance disks thereof, which are capable of
preventing reduction of the mechanical strength of the thrust
balance disks due to excessive heating up by bleed gas, a portion
of the fuel gas F, after having passed through the diffuser, is
conducted to the thrust balance disks as the bleed gas flow c.
Inventors: |
Yuri, Masanori;
(Takasago-shi, JP) ; Laurello, Vincent; (Miami,
FL) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
MITSUBISHI HEAVY INDUSTRIES,
LTD.
5-1, Marunouchi 2-chome, Chiyoda-ku
Tokyo
JP
|
Family ID: |
29549233 |
Appl. No.: |
10/156887 |
Filed: |
May 30, 2002 |
Current U.S.
Class: |
415/1 ;
415/104 |
Current CPC
Class: |
F01D 5/082 20130101;
F01D 11/04 20130101; F01D 3/02 20130101 |
Class at
Publication: |
415/1 ;
415/104 |
International
Class: |
F01D 003/02 |
Claims
What is claimed is:
1. An axial compressor, comprising a compression section which
compresses gas to be compressed; a diffuser which reduces the speed
of said compressed gas from said compression section and subjects
it to pressure recovery; a thrust balance disk which receives a
portion of said compressed gas as bleed gas after it has passed
through said compression section, and which generates a counter
thrust force which opposes thrust force which said thrust balance
disk experiences as reaction force due to said compression section
supplying said compressed gas under pressure; and a bleed gas flow
conduit which conducts a portion of said compressed gas, after it
has passed through said diffuser, to said thrust balance disk as
said bleed gas.
2. An axial compressor according to claim 1, wherein said bleed gas
is supplied to said thrust balance disk so as to flow in a
circumferential direction which is the same as the direction in
which said thrust balance disk rotates.
3. An axial compressor according to claim 2, wherein said bleed gas
is supplied to said thrust balance disk via a TOBI nozzle.
4. A method for supplying bleed gas to a thrust balance disk of an
axial compressor which comprises: a compression section which
compresses gas to be compressed; a diffuser which reduces the speed
of said compressed gas from said compression section and subjects
it to pressure recovery; and said thrust balance disk which
receives a portion of said compressed gas as bleed gas after it has
passed through said compression section, and which generates a
counter thrust force which opposes thrust force which said thrust
balance disk experiences as reaction force due to said compression
section supplying said compressed gas under pressure; wherein a
portion of said compressed gas, after it has passed through said
diffuser, is conducted to said thrust balance disk.
5. A method for supplying bleed gas to a thrust balance disk of an
axial compressor according to claim 4, wherein said bleed gas is
supplied to said thrust balance disk so as to flow in a
circumferential direction which is the same as the direction in
which said thrust balance disk rotates.
6. A method for supplying bleed gas to a thrust balance disk of an
axial compressor according to claim 5, wherein said bleed gas is
supplied to said thrust balance disk via a TOBI nozzle.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an axial compressor such
as, for example, a fuel gas compressor or the like, and to a gas
bleeding method to a thrust balance disk of such an axial
compressor. The present invention particularly relates to an axial
compressor which is capable of preventing damage or failure due to
excessive rise in the temperature of the thrust balance disk.
[0003] 2. Description of the Related Art
[0004] An example of a prior art type axial compressor will be
explained in the following with reference to the fuel gas
compressor shown in FIG. 5. It should be noted that this figure is
a cross section showing a portion of this compressor which includes
an portion of a compression section 1 at its extreme downstream
position. As shown in this figure, in the compression section 1 of
this fuel gas compressor, a plurality of stationary blades 3 which
are fixed within casing tubes 2a on the side of a casing 2 are
provided, and a plurality of moving blades 5 which are fitted
coaxially around the periphery of the rotor disks 4, and these
stationary blades 3 and moving blades 5 are arranged alternately
along the rotational axis direction of the rotor disks 4, while
being structured so as to pressurize a flow f1 of fuel gas and to
expel it in the direction shown by the arrows, due to the rotation
of these rotor disks 4.
[0005] At this time, a thrust force due to the reaction force which
accompanies this pressurized expulsion of the fuel gas flow f1 acts
upon the rotor disks 4, and the rotating body which includes these
rotor disks 4 tends to be driven in the direction opposite to the
flow direction of the fuel gas f1 (in the leftwards direction as
seen in the figure). Since an undesirably large sized bearing would
be required if it were attempted to support this large thrust force
only via a bearing, accordingly, in order to avoid this, a
plurality of thrust balance disks are provided coaxially with the
rotor disks 4. A portion of the fuel gas flow f1 which has been
compressed by the compression section 1 is taken in as a bleed gas
flow f2, and thereby these thrust balance disks 6 generate a
counter thrust force which opposes the said thrust force, so that
it becomes possible to reduce said thrust force.
[0006] Another casing ring 2b which is fitted to the interior of
the casing 2 is provided at the peripheries of these thrust balance
disks, and a plurality of labyrinth seals 7 are provided against
the inner circumferential surface of this casing ring 2b, so as to
reduce the amount of bleed gas f2 which leaks past. Upon the
upstream side of the casing ring 2b (its left side in the drawing)
there is formed a partition wall 2b1 which separates the fuel gas
flow f1 which is the main flow and the bleed gas f2, and a gas
bleed flow conduit 8 is formed inside this partition wall 2b1
against its inner circumferential surface, while a diffuser 9 is
formed against its outer circumferential surface.
[0007] The diffuser 9 is a flow conduit whose cross section area
becomes greater from its upstream side to its downstream side, and
thereby as the fuel gas flow f1 passes down from the compression
section 1 in which speed is reduced and its pressure is recovered.
The fuel gas flow f1 which exits from this diffuser 9 is discharged
towards the outside of the casing 2.
[0008] On the other hand, the bleed gas f2 which flows within the
bleed gas flow conduit 8 reaches the thrust balance disks 6 and
presses upon these thrust balance disks 6 and the rotor disks 4 in
the rightwards direction in the figure so as to exert a counter
thrust force upon them. Moreover, this bleed gas flow f2 acts as a
seal gas flow between the outer peripheries of the thrust balance
disks 6 and the labyrinth seals 7, and then is recovered.
[0009] However, the conventional compressor described above has
problems described below.
[0010] That is, although it is essential for the thrust balance
disks 6 to maintain sufficient mechanical strength since they are
required to receive the bleed gas flow f2 and to generate the
counter thrust force, since the bleed gas flow f2 is heated up to a
high temperature due to windage loss when passing down the bleed
gas flow conduit 8 and due to windage loss when passing the
labyrinth seals 7, therefore there is the problem that there is a
danger of the thrust balance disks 6 being heated up to excessively
high temperatures, so that deterioration of their mechanical
strength may occur.
[0011] The present invention has been made in consideration of the
above problems, and objective is to provide an axial compressor,
and a method for supplying bleed gas towards a thrust balance disk
thereof, which are capable of preventing reduction of the
mechanical strength of the thrust balance disk due to excessive
temperature increase caused by such gas bleeding.
[0012] The present invention employs the following structure to
solve the above problems.
[0013] That is, according to a first aspect of the present
invention, an axial compressor comprises a compression section
which compresses gas to be compressed, a diffuser which reduces the
speed of the compressed gas from the compression section and
subjects it to pressure recovery, a thrust balance disk which
receives a portion of the compressed gas as bleed gas after it has
passed through the compression section and which generates a
counter thrust force which opposes thrust force which the thrust
balance disk experiences as reaction force due to the compression
section supplying the compressed gas under pressure, and a bleed
gas flow conduit which conducts a portion of the compressed gas
after it has passed through the diffuser to the thrust balance disk
as the bleed gas.
[0014] According to the axial compressor according to the first
aspect as above, it becomes possible to cool the thrust balance
disk efficiently with the bleed gas. That is, since in the prior
art, the structure was such that a portion of the gas to be
compressed which had a non uniform temperature distribution was
supplied to the thrust balance disk directly after exiting the
compression section, accordingly the bleed gas suffered an
undesirable temperature rise due to windage loss before arriving at
the thrust balance disk, and there was a danger of increasing the
temperature of the thrust balance disk. In contrast, by the present
invention, since the bleed gas which is taken from the exit of the
diffuser has a uniform temperature distribution since it has been
sufficiently mixed in the diffuser, and further, the bleed gas is
free from any windage loss as in the prior art, accordingly it
becomes possible to supply the bleed gas to the thrust balance disk
at a comparatively lower temperature than in the prior art.
[0015] Moreover, the axial compressor described in a second aspect
of the present invention is characterized in that the bleed gas is
supplied to the thrust balance disk so as to flow in a
circumferential direction which is the same as the direction in
which the thrust balance disk rotates.
[0016] In a conventional compressor as described above, when the
bleed gas is directly supplied at a slow relative velocity with
respect to the thrust balance disk which is rotating at a high
velocity, there is a danger of excessive increase of temperature of
the thrust disk due to rise in the temperature of the bleed gas
caused by windage loss. In contrast, with the axial compressor
described in the second aspect as above, it becomes possible to
keep the relative velocity difference between the bleed gas and the
thrust balance disk low, since the bleed gas is supplied so as to
follow the thrust balance disk in the same circumferential
direction as its direction of rotation. At this time the
temperature of the bleed gas which is experienced by the thrust
balance disk (i.e. which impinges thereupon) is only its relatively
low static temperature which is the result of subtracting its
dynamic temperature from its total temperature, and accordingly it
becomes possible to cool the thrust balance disk effectively.
Furthermore, it becomes possible to reduce the drive power which is
required for driving the compression section, due to the impact
force of the bleed gas in the same circumferential direction as the
direction of rotation of the thrust balance disk.
[0017] Moreover, the axial compressor described according to a
third aspect of the present invention is characterized in that the
bleed gas is supplied to the thrust balance disk via a TOBI nozzle
(Tangential OnBoard Injection Nozzle). According to the axial
compressor described in claim 3 as above, it becomes possible to
supply the bleed gas to the thrust balance disk while accurately
following its motion.
[0018] According to a fourth aspect of the present invention, a gas
bleeding method to a thrust balance disk of an axial compressor
comprises a compression section which compresses gas to be
compressed, a diffuser which reduces the speed of the compressed
gas from the compression section and subjects it to pressure
recovery, and the thrust balance disk which receives a portion of
the compressed gas as bleed gas after it has passed through the
compression section and which generates a counter thrust force
which opposes thrust force which the thrust balance disk
experiences as reaction force due to the compression section
supplying the compressed gas under pressure, wherein a portion of
the compressed gas after it has passed through the diffuser, is
conducted to the thrust balance disk.
[0019] According to the gas bleeding method to a thrust balance
disk of an axial compressor in the fourth aspect of the present
invention, just as in the case of the first aspect as above, it
becomes possible to cool the thrust balance disk by the bleed gas
in an efficient manner.
[0020] Moreover, the gas bleeding method to a thrust balance disk
of an axial compressor according to a fifth aspect of the present
invention is characterized in that the bleed gas is supplied to the
thrust balance disk so as to flow in a circumferential direction
which is the same as the direction in which the thrust balance disk
rotates.
[0021] According to the gas bleeding method to a thrust balance
disk of an axial compressor described in the fifth aspect, just as
in the case of the second aspect as above, it becomes possible to
cool the thrust balance disk efficiently, also it becomes possible
to reduce the amount of drive power which is required for driving
the compression section.
[0022] The gas bleeding method to a thrust balance disk of an axial
compressor according to a sixth aspect of the present invention is
characterized in that the bleed gas is supplied to the thrust
balance disk via a TOBI nozzle.
[0023] According to the gas bleeding method to a thrust balance
disk of an axial compressor described in the sixth aspect, just as
in the case of the third aspect as above, it becomes possible to
supply the bleed gas to the thrust balance disk while accurately
LIZ following its motion.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 is a cross section of an essential portion of a
preferred embodiment of the axial compressor according to the
present invention, including a portion of a compression section
thereof which is at its furthest downstream position, as seen in a
cross section plane containing the rotational axis thereof.
[0025] FIG. 2 is a magnified sectional view of a portion A of FIG.
1, showing a portion of this same essential portion of the axial
compressor.
[0026] FIG. 3 is a sectional view of the same portion of the axial
compressor shown in
[0027] FIG. 2, taken in a sectional plane shown by the arrows B-B
in FIG. 2.
[0028] FIG. 4 is a cross section of the same portion of the axial
compressor shown in FIG. 2, taken in a sectional plane shown by the
arrows C-C in FIG. 2.
[0029] FIG. 5 is a cross section of an essential portion of an
example of a prior art axial compressor, including a portion of a
compression section thereof which is at its furthest downstream
position, as seen in a cross sectional plane containing the
rotational axis thereof.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0030] Although a preferred embodiment of the axial compressor and
of the method for supplying bleed gas to the thrust balance disk
thereof will be described in the following with reference to the
figures, of course the present invention is not to be considered as
being limited to these preferred embodiments. Here, FIG. 1 is a
cross section of an essential portion of a preferred embodiment of
the axial compressor according to the present invention including a
portion of a compression section thereof which is at its furthest
downstream position, as seen in a cross sectional plane containing
the rotational axis thereof. Furthermore, FIG. 2 is a magnified
sectional view of a portion A of FIG. 1, showing a portion of this
same essential portion of the axial compressor. FIG. 3 is a cross
section of the same portion of the axial compressor shown in FIG.
2, taken in a sectional plane shown by the arrows B-B in FIG. 2.
FIG. 4 is a sectional view of the same portion of the axial
compressor shown in FIG. 2, taken in a sectional plane shown by the
arrows C-C in FIG. 2.
[0031] It should be noted that in the explanation of these
preferred embodiments, by way of example, it will be supposed that
the axial compressor according to the present invention is a fuel
gas compressor which compresses and expels fuel gas.
[0032] The fuel gas compressor according to this preferred
embodiment of the present invention shown in FIG. 1 comprises a
compression section 10 which compresses fuel gas F (gas to be
compressed), a diffuser 20 which reduces the speed of the fuel gas
from this compression section 10 and recovers the pressure thereof,
a plurality of thrust balance disk 30 which receive a portion of
the bleed gas flow c of fuel gas F after it has passed through the
compression section 10 and which generate a counter thrust force BF
opposed to the thrust force TF which is received by the compression
section 10 as reaction due to the compression and expulsion of fuel
gas F, and a casing 4 which houses these elements in its
interior.
[0033] Moreover, in the following explanation, the upstream side
with respect to the flow direction of the fuel gas F (the left side
of the drawing paper in FIG. 1) will be referred to as the
"upstream side" , while conversely the downstream side with respect
to the flow direction of the fuel gas F (the right side of the
drawing paper in FIG. 1) will be referred to as the "downstream
side". Furthermore, the direction of the rotational axis of a
compression section 10 and of thrust balance disks 30 (the left to
right direction upon the FIG. 1 drawing paper) will be referred to
as the "axial direction".
[0034] The compression section 10 there are comprised a plurality
of rotor disks 11, a plurality of moving blades 12 which are
coaxially fitted to the periphery of the rotor disks 11, and a
plurality of stationary blades 13 which are fixed inside casing
rings 40a on the side of the casing 40, and these stationary blades
12 and moving blades 13 are arranged alternately along the
rotational axis of the rotor disks 11, the fuel gas F is compressed
and expelled in the direction shown by the arrows due to the
rotation of the rotor disks 11.
[0035] The shape of a compression flow conduit 14 which is defined
between the outer peripheries of the rotor disks 11 and the inner
circumferential surfaces of the casing rings 40a is such as to
narrow down from its upstream side towards its downstream side. The
stationary blades 13 are respectively fixed to the inner peripheral
surfaces of the casing rings 40a and are lined up along the
circumferential direction, taking the axis thereof as a center, and
moreover are arranged to alternate with the moving blades 12, as
seen in the axial direction.
[0036] Due to the rotation of the rotor disks 11 and because of the
rotation of the moving blades 12 as well, the fuel gas F in the
compression flow conduit 14 is compressed and set into flow (the
main flow) in the downstream direction.
[0037] The diffuser 20 is a flow conduit whose flow conduit cross
section area increases from its upstream side towards its
downstream side and it slows down the speed of the fuel gas F which
has been compressed and expelled from the compression section 10
while recovering the pressure thereof. The fuel gas F which has
exited from this diffuser 20 is discharged towards the exterior of
the casing 40.
[0038] The thrust balance disks 30 generate a counter thrust force
BF to oppose the thrust force TF by taking in a portion of the fuel
gas F which has been compressed by the compression section 10 as
bleed gas, and thus it becomes possible to reduce the thrust force
TF.
[0039] Another casing ring (which is a tubular member disposed at
the downstream side of the compression section 10, and which is
denoted by the reference symbol 40b since it is provided separately
from the casing rings 40a) is provided at the peripheries of these
thrust balance disks 30 and is fixed to the interior of the casing
40, and a plurality of labyrinth seals 31 are provided between said
thrust balance disks 30 and said casing ring 40b, so as to reduce
the amount of leakage of bleed gas c. A partition wall 40b1 is
formed on the upstream side (the left side in the figure) of the
casing ring 40b so as to partition between the main flow of fuel
gas F and the bleed gas flow c, and the diffuser 20 is formed
between the outer peripheral surface of this partition wall 40b1
and the inner peripheral surface of the casing ring 40a.
[0040] In the fuel gas compressor according to this preferred
embodiment of the present invention is characterized in that a
portion of the fuel gas F, after it has passed through the diffuser
20, is supplied to gas bleed flow conduits 50 which conduct it to
the thrust balance disks 30 as said bleed gas c.
[0041] Because of the provision of these bleed gas flow conduits
50, it becomes possible efficiently to cool the thrust balance
disks 30 by this bleed gas c. That is, conventionally, since the
structure is such that, directly after having passed through the
compression section 1, a portion of the fuel gas f1 which has an
unequal temperature distribution in the radial direction with
respect to the axial direction as a center is conducted to the
thrust balance disks 6 directly without passing through the
diffuser 9, accordingly the bleed gas c undesirably suffers a
temperature rise due to windage loss before it arrives at the
thrust balance disks 6, and therefore there is a danger of
increasing the temperature of these thrust balance disks 6. By
contrast to this, in the preferred embodiment of the present
invention, since the structure is such that the bleed gas c is
taken out after having exited from the diffuser 20 with an equal
temperature distribution due to being sufficiently mixed via the
diffuser 20, and moreover without having suffered any windage loss
such as occurred in the prior art, accordingly it is possible to
supply this bleed gas c to the thrust disks 30 at a comparatively
lower temperature than in the prior art.
[0042] Each of these bleed gas flow conduits 50 is formed from a
hole 51 which is formed in the casing ring 40b and a TOBI nozzle 52
which is fixed in this perforation 51, as shown in FIG. 2. It
should be noted that these gas bleed flow conduits 50 are arranged
at mutually equally spaced angular intervals around the
circumferential direction, taking the axis of the thrust balance
disks 30 as a center.
[0043] The holes 51 are formed along the radial direction with
respect to said axis as a center, and their entrance portions are
subjected to arle processing in order to make it easier for the
bleed gas c to be taken in. And a TOBI nozzle 52 is fixed by
welding into the outlet end of each of these holes 51.
[0044] As shown in FIG. 3, each of the TOBI nozzles 52 is a roughly
"J" shaped tube member, and its discharge aperture 52b, which is at
its opposite end from the welded portion 52a by which it is fixed,
constitutes a flow conduit which is narrowed down so as to be
convergent. Due to this, the bleed gas c which enters from the hole
51 flows through the main body of the TOBI nozzle which has a
constant cross sectional area, then changes direction around
approximately a right angle towards the discharge aperture 52b,
then increases its speed as the cross sectional area of the flow
conduit narrows down at the discharge aperture 52b, and finally is
discharged to the exterior of the TOBI nozzle 52.
[0045] Furthermore, as shown in FIGS. 3 and 4, the direction of the
discharge aperture 52b of each TOBI nozzle 52 is arranged so that
it points to expel the flow of bleed gas c in the same
circumferential direction as the direction of rotation of the
thrust balance disks 30. By arranging for the method for supplying
bleed gas to the thrust balance disks 30 in this manner, it is
possible to keep the relative speed difference between the bleed
gas flow c and the thrust balance disks 30 low. Since the
temperature of the bleed gas which is experienced (i.e., whose
impact is received) by the thrust balance disks 30 is its static
temperature, which is the result of subtracting its dynamic
temperature from its total temperature, therefore it becomes
possible to cool the thrust balance disks 30 in an efficient
manner.
[0046] Yet further, it becomes possible to reduce the power which
is required for driving the compression section 10, since the
thrust balance disks 30 receive the impact force of the bleed gas c
which flows in the same rotational direction as their direction of
rotation. In other words since, with respect to the thrust balance
disks 30 which are rotating, the bleed gas flow c is sprayed so as
to assist their rotation, accordingly it becomes possible to manage
with a lower level of drive power which is required for
rotationally driving the rotor disks 11 which are set coaxially
with these thrust balance disks 30.
[0047] The sequence of flow of the bleed gas c in the fuel
compressor according to the preferred embodiment of the present
invention with the structure as described above will now be
explained in the following.
[0048] First, the rotating member which comprises the rotor disks
11 and the thrust balance disks 30 is rotated around its axis, and
the fuel gas f in the compression flow conduit 14 is driven into
the diffuser 20 while being subjected to compression action. At
this time the fuel gas F subjects the aforesaid rotating member to
a thrust force T which pushes it towards the upstream side.
[0049] The fuel gas F which has been discharged from the diffuser
20 is discharged in this state to the exterior of the casing 40,
and at this point a portion thereof is introduced into the bleed
gas flow conduit 50 as the bleed gas flow c. The directions of the
trajectories of the flows of the bleed gas c through the bleed gas
flow conduit 50 are corrected by the TOBI nozzles 52, and these
bleed gas flows are then sprayed in towards the thrust balance
disks 30 so as to follow their rotation. While the bleed gas c
functions to cool the thrust balance disks 30 and to assist their
rotation, it also serves as a flow of seal gas which flows between
the outer peripheries of the thrust balance disks 30 and the
labyrinth seal 31, and is then recovered.
[0050] The fuel compressor and the method for supplying bleed gas
towards the thrust balance disks 30 thereof described above provide
the following beneficial results. That is, the fuel compressor of
this preferred embodiment of the present invention employs a
structure and a method with which a portion of the flow F of fuel
gas is conducted to the thrust balance disks 30 as bleed gas c
after passing through the diffuser 20. Due to this the fuel gas
flow F, which is at a comparatively low temperature after having
passed through the diffuser 20, is supplied to the thrust balance
disks 30 as bleed gas c, accordingly it is possible to cool the
thrust balance disks 30 efficiently, and it becomes possible to
prevent deterioration of the mechanical strength of the thrust
balance disks 30 due to excessive heating up from the bleed gas
c.
[0051] Furthermore, the fuel compressor of this preferred
embodiment of the present invention utilizes a structure and a
method with which the bleed gas c flows in a circumferential
direction which is the same as the rotational direction of the
thrust balance disks 30. Due to this it becomes possible to cool
the thrust balance disks 30 more efficiently, since, with regard to
the temperature of the bleed gas which impinges upon the thrust
balance disks 30, the bleed gas c is only at its static temperature
which is the result of subtracting its dynamic temperature from its
total temperature. Yet further, it also becomes possible to perform
drive power recovery, since it is possible to reduce the drive
power which is required for driving the compression section 10, due
to the impacting force of the bleed gas c which flows in the same
circumferential direction as the rotational direction of the thrust
balance disks 30.
[0052] Although, in the explanation of the preferred embodiments of
the device and method of the present invention detailed above, the
present invention has been described by way of example in terms of
its application to a fuel gas compressor, it should be understood
that the present invention is not limited to this example, it can
be applied to an axial compressor which compresses some different
gas to be compressed.
[0053] Moreover, although in the preferred embodiments of the
device and method of the present invention detailed above the TOBI
nozzles 52 were utilized to direct the bleed gas c in the same
circumferential direction as the direction of rotation of the
thrust balance disks 30, the present invention is not to be
considered as being limited to the use of such TOBI nozzles, other
structures could also be employed. That is, it would also be
acceptable to process the nozzles directly upon the casing ring
40b.
[0054] The structure of the axial compressor described in the first
aspect has a bleed gas flow conduit through which a portion of the
gas to be compressed, after it has left the diffuser, is conducted
to the thrust balance disk as bleed gas. According to this
structure, the gas which has left the diffuser and is at a
comparatively low temperature is supplied to the thrust balance
disk as bleed gas, and therefore it is possible to cool the thrust
balance disk efficiently, and it becomes possible to prevent
deterioration of the mechanical strength of the thrust balance disk
due to excessive heat increase because of the bleed gas.
[0055] Furthermore, with the axial compressor described in the
second aspect, a structure is furthermore employed in which the
bleed gas flows in a circumferential direction which is the same as
the direction in which the thrust balance disk rotates. According
to this structure, the temperature of the bleed gas which is
experienced by the thrust balance disk is only its relatively low
static temperature which is the result of subtracting the dynamic
temperature from its total temperature, and accordingly it becomes
possible to cool the thrust balance disk more effectively.
Furthermore, it becomes possible to reduce the drive power which is
required for driving the compression section, due to the impact
force of the bleed gas in the same circumferential direction as the
direction of rotation of the thrust balance disk, and therefore it
becomes possible to perform recovery of drive power.
[0056] Furthermore, with the axial compressor described in the
third aspect, a structure is furthermore employed in which the
supply of bleed gas is performed via a TOBI nozzle. According to
this structure, it becomes possible to supply the bleed gas so as
accurately to follow the rotational movement of the thrust balance
disk.
[0057] Furthermore, with the method for supplying bleed gas to a
thrust balance disk of an axial compressor described in the fourth
aspect, a method is utilized in which a portion of the gas to be
compressed, after it has left the diffuser, is conducted to the
thrust balance disk as bleed gas. According to this method, just as
with the structure of the first aspect described above, it is
possible to prevent deterioration of the mechanical strength of the
thrust balance disk due to excessive heat increase because of the
bleed gas.
[0058] Furthermore, with the method for supplying bleed gas to a
thrust balance disk of an axial compressor described in the fifth
aspect, a procedure is furthermore employed of flowing the bleed
gas in a circumferential direction which is the same as the
direction in which the thrust balance disk rotates. According to
this method, in the same way as with the second aspect described
above, it becomes possible to cool the thrust balance disk more
effectively, and furthermore it becomes possible to perform
recovery of drive power by reducing the drive power which is
required for driving the compression section.
[0059] Furthermore, with the method for supplying bleed gas to a
thrust balance disk of an axial compressor described in the sixth
aspect, a procedure is furthermore employed of supplying the bleed
gas via a TOBI nozzle. According to this method, in the same manner
as with the third aspect described above, it becomes possible to
supply the bleed gas so as accurately to follow the rotational
movement of the thrust balance disk. It should be understood that,
although the present invention has been shown and described in
terms of certain preferred embodiments thereof, and with reference
to the drawings, the various particular features of these
embodiments and of the drawings are not to be considered as being
limitative of the invention; variations and omissions to the
details of any particular embodiment are possible, within the scope
of the appended claims.
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