Information
-
Patent Grant
-
6751962
-
Patent Number
6,751,962
-
Date Filed
Wednesday, March 8, 200024 years ago
-
Date Issued
Tuesday, June 22, 200420 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
Field of Search
US
- 060 3931
- 060 3932
- 060 752
- 060 759
- 060 760
- 060 800
-
International Classifications
-
Abstract
In a tail tube seal structure of gas turbine, a U-shaped groove is provided at one side of a tail tube seal where a flange of a tail tube outlet is fitted, and a pi-shaped groove is provided at other side of the tail tube seal where a gas pass side flange end is fitted, thereby composing the seal of the connection area. Inclined cooling holes are drilled in the tail tube seal in addition to the cooling holes existing conventionally. The cooling air flows in from the inclined holes and cools the gas pass side of the groove due to the film effect. Therefore, the difference in thermal expansion between the groove and flange end is decreased, the wear of this area is decreased, and the reliability of the seal is enhanced.
Description
FIELD OF THE INVENTION
The present invention relates to a tail tube structure of gas turbine combustor. More particularly, this invention relates to a structure for enhancing the performance of gas turbine by increasing the cooling effect in the tail tube seal, decreasing the cooling air flow to save the air consumption, and decreasing the load of the compressor.
BACKGROUND OF THE INVENTION
FIG. 9
is a general structural diagram of a combustor of a gas turbine. Reference numeral
80
indicates a combustor. This combustor
80
is fixed in a casing
81
. Reference numeral
82
indicates a pilot fuel nozzle. Pilot fuel to be used for ignition is supplied to the pilot fuel nozzle
82
. Reference numeral
83
indicates a main fuel nozzle. A plurality of main fuel nozzles (for example eight in number) are arranged in a circle around the pilot fuel nozzle
82
. Reference numeral
84
indicates an inner tube, and
85
indicates a tail tube. The inner tube
84
and the tail tube
85
guide a high temperature combustion gas
200
towards an outlet
86
of the tail tube
85
(hereafter tail tube outlet). Reference numeral
87
indicates a bypass pipe, and
88
indicates a bypass valve. The bypass valve
88
gets opened when the combustion air becomes insufficient because of the fluctuations in the load. When the bypass valve
88
gets opened, a passage is created for guiding the air in the casing
81
into the combustor
80
. Reference numeral
89
indicates a seal section. This seal section
89
is provided at the peripheral end of the tail tube outlet
86
as described below. The seal section
89
is intended to seal the connection area with gas passage (alternatively the “gas pass”)
100
of the gas turbine. A plurality of such combustors
80
(for example sixteen in number) are disposed around the rotor in the casing
81
. Each combustor
80
supplies the high temperature combustion gas into the gas pass
100
. This combustion gas expands in the gas pass
100
to work and rotate the rotor.
In the combustor having such constitution, the fuel from the main fuel nozzle
83
is mixed with the air sucked from around. The mixture of fuel and air is ignited by the flame of the pilot fuel from the pilot fuel nozzle
82
. The mixture burns to form a high temperature combustion gas
200
. The high temperature combustion gas
200
is supplied from the tail tube outlet
86
into the gas pass
100
through the inner tube
84
and tail tube
85
. Since the wall of the inner tube
84
and the wall of the tail tube
85
always come in contact with the high temperature combustion gas
200
, a cooling passage for passing cooling air is provided in these walls in order to cool them. Moreover, the tail tube outlet
86
is connected to the periphery of the inlet of the gas pass
100
through the seal section
89
. This seal section
89
is also cooled using the cooling air.
FIG. 10
is a magnified sectional view of portion Y in FIG.
9
. This figure shows a detail structure of a conventional tail tube seal. Reference numeral
89
indicates the entire seal section. A flange
86
a
is formed around the tail tube outlet
86
. The wall of the tail tube is exposed to high temperature combustion gas
200
, for example, the temperature of the gas as high as 1500 degree centigrade. However, multiple passages (not shown) for cooling air are formed in the wall of the tail tube
85
, and the wall is cooled by the cooling air. Further, a groove
90
for cooling air is also formed around the tail tube outlet
86
. The tail tube outlet
86
is cooled by passing the cooling air in this groove
90
.
The tail tube outlet
86
is connected to the gas pass
100
through a tail tube seal
61
. One end of the tail tube seal
61
has a U-shaped groove
61
a.
A peripheral flange
86
a
of the tail tube outlet
86
is fitted into this groove
61
a.
The other end of the tail tube seal
61
has a pi-shaped groove
61
b.
Flange ends
102
a,
103
a
of an outer shroud
102
and an inner shroud
103
of a first stage stationary blade
101
in the gas pass
100
are fitted into this groove
61
b,
thereby sealing the connection area.
Since the tail tube seal
61
is also exposed to high temperature combustion gas
200
as mentioned above, multiple cooling holes
61
c
are drilled around the tail tube seal
61
in a direction which is perpendicular to the direction into which the gas flows at the inlet of the gas pass
100
. High pressure air
91
flows in from around the combustor in the casing and cools the wall of the tail tube seal
61
. After cooling, this air flows into the gas pass
100
. The amount of cooling air required to cool the tail tube seal
61
is about 1 to 2% of the amount of compressed air discharged from the compressor.
Thus, in the tail tube seal of the conventional gas turbine combustor, air holes
61
c
are drilled on the periphery of the tail tube seal
61
and the tail tube seal
61
is cooled by passing cooling air
91
in the air holes
61
c.
The periphery of the holes
61
c
is cooled by passing cooling air into the holes
61
c,
however, the side of the groove
61
b
connecting to the gas pass
100
side is not cooled sufficiently by passing cooling air into the holes
61
c
alone. As the cooling is insufficient, the flange ends
102
a,
103
a
towards the gas pass side expand due to thermal expansion. This thermal expansion of the flange ends
102
a,
103
a
generates a frictional force at the contact with the groove
61
b
and the groove
61
b
is worn. Thus, the performance of the tail tube seal
61
is impaired.
Moreover, the amount of air required to cool the tail tube seal
61
is about 1 to 2% of the entire amount of compressed air discharged from the compressor. However, it is desirable that this air consumption is as little as possible, because, when the air consumption is less, the efficiency of the compressor can be improved and the performance of the gas turbine can be enhanced. Such a decrease in the air consumption was in demand but was not realized till present.
SUMMARY OF THE INVENTION
It is an object of the present invention to present a tail tube seal structure of a combustor capable of improving the cooling structure of the tail tube seal of a combustor of gas turbine, raising the cooling effect, curtailing the amount of air by cooling by a smaller amount of air, and contributing to an upgraded performance of the entire gas turbine.
According to one aspect of the present invention, the air in the casing flows in from a plurality of inclined cooling holes and flows out obliquely into the gas pass, and cools the wall contacting with the gas passage in the groove in which the flange end of the gas pass is fitted by film effect, the cooling in this area is reinforced. Owing to this cooling, the conventional problem of wear due to difference in thermal expansion between the fitting section of the member and the gas pass side flange end to be fitted is decreased, and the reliability of the tail tube seal structure is enhanced.
Further, the gas pass is generally in a cylindrical shape, and the inclined cooling holes are formed at specific intervals in the entire peripheral direction. Therefore, the inner wall of the gas pass can be cooled uniformly and efficiently also in the peripheral direction.
Further, the air flowing out from the inclined cooling holes flows smoothly along the inner wall of the gas pass side formed of a smooth curvature. Therefore, the film cooling effect is enhanced, and the cooling of the flange end at the gas pass side is further effective.
According to one aspect of the present invention, the seal member is fitted outside to the flange of the outer circumference of the tail tube outlet, and also fitted to the protrusion at the gas pass side on the outer periphery of the tail tube outlet wall. Therefore, the member itself does not come in contact with the high temperature combustion gas. Hence, it is not necessary to cool the member itself, and hence cooling holes and cooling are not needed. Instead, to reinforce cooling of the tail tube outlet wall, inclined cooling holes are provided around the tail tube outlet wall, and air is passed in the cooling holes to flow out in the gas passage to cool, and this cooling is a further addition to the conventional cooling of the tail tube wall inside. Therefore, in the present invention, the effect of the high temperature combustion gas in the tail tube seal is much smaller than in the prior art, and the consumption of cooling air is saved substantially.
Further, the seal member is placed in the fitting section between the tail tube outlet flange and the protrusion member at the gas pass side, the tail tube outlet peripheral flange end and the gas pass side protrusion are sealed securely, and the effect of the present invention is further encouraged.
Further, a brush seal is used. This brush seal seals by contacting with the smooth plane of the flange end of the gas pass side, and if a relative deviation occurs between the gas pass side flange end and the tail tube side, by sliding of the brush seal. Therefore, it is possible for the brush seal to move relatively depending on the deviation, and excessive force is not applied to the connection area, so that the reliability of the tail tube seal is enhanced.
Further, since a brush seal is used, in addition to the above effects, if a relative deviation occurs between the gas pass inlet side and the tail tube side, it is possible to move relatively, corresponding to this deviation, by sliding of the brush seal without spoiling the sealing performance, and excessive force is not applied to the connection area, so that the effects of the present invention may be assured.
Further, the shape of the inclined cooling holes is either circular or elliptical, and the hole shape can be selected depending on the type or structure of combustor, or by forming slender holes, the number of holes may be decreased, and the shape of the inclined cooling holes may be selected appropriately depending on the size or shape of the combustor, size at the gas pass side and other conditions, and the freedom of design is wider, which contributes to optimum designing.
According to still another aspect of the present invention, from the variety of tail tube seal structures exemplified herein, the best tail tube seal structure can be selected depending on the capacity or type of the gas turbine, and by using it, a gas turbine enhanced in the cooling effect in the tail tube seal, curtailed in the amount of cooling air, and enhanced in performance is realized.
Other objects and features of this invention will become apparent from the following description with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a partial sectional view of a tail tube seal structure of gas turbine combustor according to a first embodiment of the present invention;
FIG. 2
is a partial sectional view of a tail tube seal structure of gas turbine combustor according to a second embodiment of the present invention;
FIG. 3
is a partial sectional view of a tail tube seal structure of gas turbine combustor according to a third embodiment of the present invention;
FIG. 4
is a partial sectional view of a tail tube seal structure of gas turbine combustor according to a fourth embodiment of the present invention;
FIG. 5
is a partial sectional view of a tail tube seal structure of gas turbine combustor according to a fifth embodiment of the present invention;
FIG. 6
is a partial sectional view of a tail tube seal structure of gas turbine combustor according to a sixth embodiment of the present invention;
FIG. 7A
to
FIG. 7F
are representative of alternative cross sectional views when seen along the arrows
7
—
7
shown in
FIG. 6
, in which
FIG. 7A
to
FIG. 7C
show alternative examples, and
FIG. 7D
to
FIG. 7F
show side views, respectively, of
FIGS. 7A-7C
;
FIG. 8
is a general structural diagram of gas turbine applying the tail tube seal structure in any one of the first to sixth embodiments of the present invention;
FIG. 9
is a general structural diagram of gas turbine combustor; and
FIG. 10
is a cross sectional view of a tail tube seal structure of gas turbine combustor in the conventional art.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings, preferred embodiments of the present invention are described in detail below.
FIG. 1
is a cross sectional view of a tail tube seal structure of a gas turbine combustor according to a first embodiment of the present invention. The figure shows only the inside part. The tail tube outlet
86
side is provided with a cooling groove
90
in the circumference in the same manner as in the conventional art and it is cooled by the cooling air. The peripheral flange
86
a
of the tail tube outlet
86
and the flange
103
a
of the gas pass side are connected through grooves
1
a,
1
b
of the tail tube seal
1
.
The shape of the tail tube seal
1
is basically the same as that of the conventional tail tube seal
61
shown in
FIG. 10
, except that a cooling hole
1
d
is provided therein. The cooling hole
1
c
is drilled at the same position the cooling hole
61
c
shown in FIG.
10
. Air
91
is allowed to flow out into the inner wall of the connection area of the tail tube seal
1
thereby cooling the periphery. Moreover, in this embodiment, the inclined cooling hole
1
d
is drilled obliquely in the wall
2
of the gas passage side of the groove
1
b
and it opens to the gas passage side.
Cooling air
92
flows into this cooling hole
1
d
from outside, and the air
92
is blown out obliquely from the wall of the high temperature gas passage side of the pi-shaped groove
1
b,
and this portion is cooled, and the part of the groove
1
b
to which the gas pass side flange end
103
a
is fitted is cooled, thereby lessening the effect of difference in thermal expansion between the tail tube seal member of gas pass side and the flange end
103
a
on the junction, and the wear of the tail tube seal
1
and flange end
103
a
is decreased, and hence the reliability is enhanced.
Moreover, when the inclined cooling holes
1
d
are provided at specific intervals on the entire peripheral direction of the wall
2
along the gas pass of the tail tube seal
1
, the inner wall of the gas pass can be cooled uniformly and efficiently.
FIG. 2
is a cross sectional view of a tail tube seal structure of gas turbine combustor according to the second embodiment of the present invention. The figure shows only the inside part. The structure of the tail tube outlet
86
side is basically the same as shown in FIG.
1
. Namely, the tail tube outlet
86
and the gas pass side are connected by a tail tube seal
11
, and the periphery is sealed. The shape of the tail tube seal
11
is basically same as the tail tube seal
1
shown in
FIG. 1
, except that a cooling hole lid and a flange slope
12
at the gas pass side are different.
In the tail tube seal
11
, a cooling hole
11
c
is formed at the same position as the cooling hole
1
c
shown in
FIG. 1
, and air
91
flows out from the wall of the gas passage at the inner side, and the periphery of this portion is cooled. Moreover, in this embodiment, the inclined cooling hole
11
d
is formed obliquely in a wall
13
of the gas passage side of the groove
11
b.
Further, the flange slope
12
is provided by reducing the flange end
103
a
fitted in the groove
11
b
into the gas flow direction smoothly from the outlet of the groove
11
b.
According to the second embodiment, the connection inlet side of the tail tube seal
11
is cooled by the air
91
flowing out of the cooling hole
11
c
in the same manner as in the conventional art. In addition, the wall of the gas passage side of the groove lib is cooled by the cooling air
93
flowing out from the inclined cooling hole
11
d.
Therefore, as in the first embodiment shown in
FIG. 1
, it is effective to reduce the wear due to a difference in thermal expansion between the groove
11
b
and the flange end
103
a
fitted thereto.
Further, in the second embodiment, air
93
flowing out from the cooling hole
11
d
flows out to the gas pass side along the smooth flange slope
12
at the gas pass side and cools the flange end
103
a
and the flange slope contiguous thereto by the film effect, thereby eliminating the difference in thermal expansion between the groove
11
b
of the tail tube seal
11
and the gas pass side flange
103
a,
so that the cooling effect of the upper partition of the groove
11
b
may be further enhanced.
FIG. 3
is a cross sectional view of a tail tube seal structure of gas turbine combustor according to the third embodiment of the present invention. The figure shows only the inside part. As shown in this figure, an outlet wall
186
projecting towards the outer side of the flange
86
a
is provided around the end portion of the tail tube outlet
86
. Many cooling holes
187
are drilled in the outlet wall
186
along the periphery at an upward inclination toward the outlet. The tail tube seal
21
has a groove
21
a
fitted to the flange
86
a
at the tail tube outlet
86
side at one side, and a pi-shaped groove
21
b
at the other end. The structure of fitting to the gas pass side flange end
103
a
is basically same as the shape of the first and second embodiments shown in FIG.
1
and
FIG. 2. A
member is provided for fitting to an outer peripheral flange at the tail tube outlet
86
at one side, and fitting to a protrusion projecting toward upstream side at the outer side of the wall periphery of the tail tube outlet
86
from the junction of the gas pass inlet end periphery at other side.
In the third embodiment, a seal wire
22
is inserted between the groove
21
a
and the flange
86
a
leading end at the tail tube outlet
86
side. Further, a V-seal
23
is inserted between the groove
21
b
and the leading end of the flange end
103
a
at the gas pass side fitted thereto. This structure seals between the tail tube outlet
86
side and gas pass side.
According to the third embodiment, high temperature combustion gas
200
flows out to the gas pass side while contacting with an outlet wall
186
at the tail tube outlet
86
, but it is not designed to contact with the tail tube seal
21
. Therefore, it is not required to cool the tail tube seal
21
because it is assembled at the inner side not contacting directly with the gas passage, and hence cooling air is not needed. Instead, the tail tube side outlet wall
186
is cooled by the cooling air
94
flowing out from the cooling hole
187
, but this cooling is a further addition to the cooling of the wall surface of the tail tube, and the amount of cooling air can be curtailed as compared to that required conventionally.
FIG. 4
is a cross sectional view of a tail tube seal structure of gas turbine combustor according to the fourth embodiment of the present invention. The figure shows only the inside part. The structure of the tail tube outlet
86
is the same as that shown in FIG.
1
and FIG.
2
. Namely, the shape of the tail tube seal
31
is basically the same as the tail tube seal
11
shown in
FIG. 2
, except that a brush seal
32
is provided.
As shown in
FIG. 4
, a U-shaped groove
31
a
is provided at one side of the tail tube seal
31
. Further, a flange
86
a
of the tail tube outlet
86
is fitted in, and a pi-shaped groove
31
b
provided at other side. Further, a brush seal
32
is provided in the groove
31
b.
The brush of the brush seal
32
makes a contact with the side of the inner shroud
103
of the gas pass side thereby sealing this end.
In the fourth embodiment, the cooling hole
31
c
of the tail tube seal
31
is provided at the same position as the cooling hole
11
c
in the second embodiment shown in FIG.
2
. Air
91
flows out to the wall of the inside gas passage to cool the surrounding area, and cooling air
95
flows obliquely into the cooling hole
31
d
to cool the wall
33
of the gas passage side of the groove
31
b,
and the air
95
flowing out from the cooling hole
31
d
flows out along the inner shroud
103
, and cools the protrusion of the brush seal
32
and the end face of the inner shroud.
Therefore, the same effect as the second embodiment explained in
FIG. 2
is obtained, and the brush seal
32
in the groove
31
b
can be cooled effectively. Further, by using the brush seal
32
, if the tail tube seal
31
and the gas pass side inner shroud
103
move relatively, it is allowed to move relatively by sliding of the brush, and excessive force is not applied to the groove
31
b.
FIG. 5
is a cross sectional view of a tail tube seal structure of gas turbine combustor according to the fifth embodiment of the present invention. The figure shows only the inside part. The structure of the tail tube outlet
86
is same as the structure of the third embodiment shown in FIG.
3
. Namely, the shape of the tail tube
41
is basically same as that of the tail tube seal
21
shown in
FIG. 3
, however, the difference is that, a brush seal
42
is used.
As shown in
FIG. 5
, a U-shaped groove
41
a
is provided at one side of the tail tube seal
41
. Further, a flange
86
a
of the tail tube outlet
86
is fitted, and a pi-shaped groove
41
b
is provided at other side. Further, a brush seal
42
is provided in the groove
41
b.
The brush of the brush seal
42
makes contact with the side of the inner shroud
103
of the gas pass side thereby sealing this end face. Further, a seal wire
22
is inserted between the groove
41
a
and the leading end of the flange
86
a
at the tail tube outlet
86
side, and the tail tube outlet
86
side is sealed.
In the fifth embodiment, same as in the third embodiment shown in
FIG. 3
, the high temperature combustion gas
200
flows out to the gas pass side in contact with an outlet wall
186
at the tail tube outlet
86
, but it is not designed to contact with the tail tube seal
41
. Therefore, it is not required to cool the tail tube seal
41
because it is assembled at the inner side not contacting directly with the gas passage, and hence cooling air is not needed. Instead, the tail tube side outlet wall
186
is cooled by the cooling air
94
flowing out from the cooling hole
187
, but this cooling is a further addition to the cooling of the wall surface of the tail tube, and the amount of cooling air can be curtailed as compared to that required conventionally.
Further, by using the brush seal
42
, if the tail tube seal
41
and the gas pass side inner shroud
103
should move relatively, it is allowed to move relatively by sliding of the brush, and excessive force is not applied to the groove
31
b.
FIG. 6
is a cross sectional view of a tail tube seal structure of gas turbine combustor according to the sixth embodiment of the present invention. The figure shows only the inside part. The structure of the tail tube outlet
86
and shape of the tail tube seal
51
are basically the same as in the second embodiment shown in FIG.
2
. The feature of this embodiment lies in the shape and layout of the cooling holes
51
d
shown in FIG.
7
.
As shown in
FIG. 6
, the tail tube seal
51
has a U-shaped groove
51
a
at one side in which a flange
86
a
is inserted, and a groove
51
b
is provided at other side, and the flange end
103
a
is fitted to compose the seal section. Air
91
flows out from a cooling hole
51
c
to the wall of the gas passage at the inner side, and the periphery of this portion is cooled. Moreover, an inclined cooling hole
51
d
is formed obliquely in a wall
53
of the gas passage side of the groove
51
b.
Further, the flange slope
12
is provided for reducing the flange end
103
a
fitted in the groove
51
b
into the gas flow direction smoothly from the outlet of the groove
51
b.
The structure explained here is basically the same as that shown in FIG.
2
.
According to the sixth embodiment, the connection inlet side of the tail tube seal
51
is cooled by the air
91
flowing out of the cooling hole
51
c
in the same manner as in the conventional art. Further, the wall of the gas passage side of the groove
51
b
is cooled by the cooling air
93
flowing out from the inclined cooling hole
51
d.
Therefore, in the same manner as in the second embodiment shown in
FIG. 2
, it is effective to reduce the wear due to difference in thermal expansion between the groove
51
b
and the flange end
103
a
fitted thereto.
Further, in the sixth embodiment, air
93
flowing out from the cooling hole
51
d
flows out to the gas pass side along the smooth flange slope
12
at the gas pass side, and cools the flange end
103
a
and the flange slope
12
contiguous thereto by the film effect, thereby eliminating the difference in thermal expansion between the groove
51
b
of the tail tube seal
51
and the gas pass side, so that the cooling effect of the upper partition of the groove
51
b
may be enhanced same as in the second embodiment shown in FIG.
2
.
FIG. 7A
to
FIG. 7F
show views when seen along the arrows
7
—
7
shown in
FIG. 6
(cooling hole
51
c
being omitted).
FIG. 7A
to
FIG. 7C
show alternative embodiments of the application examples, and
FIG. 7D
to
FIG. 7F
show side views, respectively, of the embodiments of
FIGS. 7A-7C
. The cooling holes
51
d
may be circular in shape as shown in FIG.
7
A and
FIG. 7D
, or may be elliptical in shape as shown in FIG.
7
B and
FIG. 7E
, or may be slender in shape as shown in FIG.
7
C and FIG.
7
F. As preferable dimensions, when the holes are circular or elliptical their diameter may be of the order of 2 mm or equivalent to 2 mm, and when the holes are slender their length may be of the order of 4 to 8 mm, their width may be of the order of 0.8 to 1.5 mm. Further, it is desirable that the holes are drilled at a pitch of about 21 mm.
FIG. 8
is a general structural diagram of a gas turbine applying any one of the tail tube seals described in the first to sixth embodiments as the tail tube seal of gas turbine combustor. As shown in this figure, the tail tube outlet
86
of the tail tube
85
in the casing
81
and the gas pass are connected through a tail tube seal
301
, and sealed. The tail tube seal
301
is any one of the tail tube seals described in the first to sixth embodiments, and is represented by reference numeral
301
.
The gas pass of the gas turbine is composed of four stages of stationary blades
101
s,
102
s,
103
s,
104
s,
and four stages of moving blades
101
M,
102
M,
103
M,
104
M. The high temperature combustion gas
200
passes through the tail tube outlet
86
through the tail tube
85
of the combustor, and is guided into the gas pass, and expanded to work and rotate the rotor. The tail tube seal
301
is selected in a proper shape for the structure of the combustor outlet unit and the inlet structure of the gas pass. As a result, the cooling effect of the tail tube seal is increased, the cooling air volume of the tail tube seal is curtailed, and it contributes to the enhancement of the performance of the entire gas turbine.
As explained above, according to the tail tube seal structure of combustor according to one aspect of the present invention, since the air in the casing flows in from the plurality of inclined cooling holes and flows out obliquely into the gas pass, and cools the wall contacting with the gas passage in the groove in which the flange end of the gas pass is fitted by film effect, the cooling in this area is reinforced. Owing to this cooling, the conventional problem of wear due to difference in thermal expansion between the fitting section of the member and the gas pass side flange end to be fitted is decreased, and the reliability of the tail tube seal structure is enhanced.
Further, since the inclined cooling holes are provided at specific intervals in the whole peripheral direction of the wall along the gas pass of the wall, it can be cooled uniformly and efficiently also in the peripheral direction. Same as above, wear of groove and its fitting flange can be decreased, and the reliability of the tail tube seal structure is enhanced.
Further, since a smooth slope is formed so that the air flowing out from the inclined cooling holes may flow smoothly along the inner wall of the gas pass side, the film cooling effect is enhanced, and cooling of the flange end portion of the gas pass side is further effective.
According to the tail tube seal structure of combustor according to another aspect of the present invention, since the member is fitted outside to the flange of the outer circumference of the tail tube outlet, and also fitted to the protrusion at the gas pass side on the outer periphery of the tail tube outlet wall, the member itself does not contact directly with the high temperature combustion gas. Therefore, it is not necessary to cool the member itself, and hence cooling holes and cooling are not needed.
Further, since the seal member is placed in the fitting section between the tail tube outlet flange and the protrusion member at the gas pass side, the tail tube outlet peripheral flange end and the gas pass side protrusion are sealed securely, and the effect of the present invention is further encouraged.
Further, since the brush seal is used, the brush seal seals by contacting with the smooth plane of the flange end of the gas pass side, and if a relative deviation occurs between the gas pass side flange end and the tail tube side, by sliding of the brush seal, it is possible to move relatively depending on the deviation, and excessive force is not applied to the connection area, so that the reliability of the tail tube seal is enhanced.
Further, since the brush seal is used, in addition to the above effects, if a relative deviation occurs between the gas pass inlet side and the tail tube side, it is possible to move relatively, corresponding to this deviation, by sliding of the brush seal without spoiling the sealing performance, and excessive force is not applied to the connection area, so that the effects of the present invention may be assured.
Further, the shape of the inclined cooling holes is either circular or elliptical, and the hole shape can be selected depending on the type or structure of combustor, or by forming slender holes, the number of holes may be decreased, and the shape of the inclined cooling holes may be selected appropriately depending on the size or shape of the combustor, size at the gas pass side and other conditions, and the freedom of design is wider, which contributes to optimum designing.
The present invention further provides a gas turbine applying a tail tube seal structure of combustor of any one of those describe above in the connection area of the tail tube outlet of the combustor and gas pass inlet, and therefore, from the variety of tail tube seal structures exemplified herein, the best tail tube seal structure can be selected depending on the capacity or type of the gas turbine, and by using it, a gas turbine enhanced in the cooling effect in the tail tube seal, curtailed in the amount of cooling air, and enhanced in performance is realized.
Although the invention has been described with respect to a specific embodiment for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art which fairly fall within the basic teaching herein set forth.
Claims
- 1. A tail tube sealing structure for a combustor having a tail tube outlet including a first flange, and a shroud with a second flange, said combustor receiving compressed air from a compressor that discharges a first amount of the compressed air, said tail tube sealing structure defining a gas passage and comprising a member having a wall defined by an inside surface and an outside surface, said member having a first groove fitting the first flange around said tail tube outlet and having a second groove having a bottom and fitting the second flange of said shroud, said member having a plurality of first cooling holes disposed at a first position in a gas flow direction and extending through the wall between the outside surface and the inside surface so as to pass cooling air into said gas passage, and a plurality of second cooling holes disposed at a second position downstream of said first position and adjacent to the first cooling holes, said second cooling holes extending through the wall between the outside surface and the inside surface in the gas flow direction and being open to said gas passage on the inside surface at a third position in the gas flow direction, the third position being located on, or downstream in the gas flow direction of, an imaginary annular curved line defined as an intersection of an imaginary plane substantially flush with the bottom of said second groove with said inside surface, said first cooling holes and said second cooling holes passing the cooling air in a second amount,whereby the film cooling effect on the inside surface is enhanced to thereby decrease frictional force generated upon contract of said member with said second flange of said shroud, and whereby the second amount of the cooling air is reduced to at most about 1 to 2% of the first amount of the compressed air discharged from said compressor.
- 2. The tail tube seal structure of a combustor according to claim 1, wherein said second cooling holes are provided at intervals around the periphery of the wall along the gas pass of said member.
- 3. The tail tube seal structure of a combustor according to claim 1, wherein a smooth slope is formed in the inner surface of the wall contiguous to the second flange so that the air flowing out from said second cooling holes may flow in the gas flow direction.
- 4. The tail tube seal structure of a combustor according to claim 1, wherein said second flange defines a smooth surface, a brush seal is provided in the second groove of said member, and said brush seal contacts with the smooth surface of said flange end.
- 5. The tail tube seal structure of a combustor according to claim 1, wherein said second cooling holes are at least one of circular or elliptical.
- 6. The tail tube seal structure of a combustor according to claim 1, wherein said second cooling holes are slender holes.
- 7. A gas turbine having a combustor with a tail tube outlet, including a first flange on the periphery of said outlet, a shroud with a second flange, said combustor receiving compressed air from a compressor that discharges a first amount of the compressed air, and a tail tube seal structure for a sealed connection between the tail tube outlet and the shroud, the tail tube outlet, the seal structure and the shroud defining a gas passage for flow of gas from an upstream position at the tail tube outlet toward a downstream position at the shroud in a gas flow direction, said tail tube seal structure comprising a member having a wall defined by an inside surface and an outside surface, said member having a first groove fitting the first flange around said tail tube outlet and having a second groove having a bottom and fitting the second flange of said shroud, said member having a plurality of first cooling holes disposed at a first position in the gas flow direction and extending through the wall between the outside surface and the inside surface so as to pass cooling air into said gas passage, and a plurality of second cooling holes disposed at a second position downstream of said first position and adjacent to the first cooling holes, said second cooling holes extending through the wall between the outside surface and the inside surface in the gas flow direction and being open to said gas passage on the inside surface at a third position in the gas flow direction, the third position being located on, or downstream in the gas flow direction of, an imaginary annular curved line defined as an intersection of an imaginary plane substantially flush with the bottom of said second groove with said inside surface, said first cooling holes and said second cooling holes passing the cooling air in a second amount,whereby the film cooling effect on the inside surface is enhanced to thereby decrease frictional force generated upon contact of said member with said second flange of said shroud, and whereby the second amount of the cooling air is reduced to at most about 1 to 2% of the first amount of the compressed air discharged from said compressor.
- 8. The tail tube seal structure of a combustor according to claim 7, wherein said second cooling holes are provided at intervals around the periphery of the wall along the gas pass of said member.
- 9. The tail tube seal structure of a combustor according to claim 7, wherein a smooth slope is formed in the inner surface of the wall contiguous to the second flange so that the air flowing out from said second cooling holes may flow in the gas flow direction.
- 10. The tail tube seal structure of a combustor according to claim 7, wherein said second flange defines a smooth surface, a brush seal is provided in the second groove of said member, and said brush seal contacts with the smooth surface of said flange end.
- 11. The tail tube seal structure of a combustor according to claim 7, wherein said second cooling holes are at least one of circular or elliptical.
- 12. The tail tube seal structure of a combustor according to claim 7, wherein said second cooling holes are slender holes.
Priority Claims (1)
Number |
Date |
Country |
Kind |
11-060321 |
Mar 1999 |
JP |
|
US Referenced Citations (9)
Foreign Referenced Citations (2)
Number |
Date |
Country |
0 615 055 |
Sep 1994 |
EP |
62-176448 |
Nov 1987 |
JP |