Gas turbine split ring

Details Gas turbine split ring Gas turbine split ring

2000-03-03

2001-08-07

Ryznic, John E. (Department: 3745)

Rotary kinetic fluid motors or pumps

With lubricating, sealing, packing or bearing means having...

C415S116000, C415S139000

Reexamination Certificate

active

06270311

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a gas turbine split ring. More particularly this invention relates to an improvement of cooling at the connection area of the split ring so as to prevent burning of end portions due to the high temperature gas and thus enhance the reliability.
BACKGROUND OF THE INVENTION
FIG. 8
is a general sectional view of a gas turbine. In
FIG. 8
, reference numeral
31
is a first stage stationary blade,
32
is a flange of the stationary blade, and
33
is its support ring. Reference numeral
34
is a first stage moving blade,
35
is a second stage stationary blade,
36
is a second stage moving blade,
37
is a third stage stationary blade,
38
is a third stage moving blade,
39
is a fourth stage stationary blade, and
40
is a fourth stage moving blade. This example is composed of four stages of blades. One stationary blade is used in each stage. A moving blade is provided between two stationary blades through a disk in the rotor peripheral direction. Thus, a plurality of stationary blades and moving blades are disposed alternately in the axial direction.
In this gas turbine, in order to enhance the turbine efficiency, it is required to elevate the temperature of the working gas. In order to keep the temperature of the metal material of the wall for forming the gas passage below an allowable temperature of the material, holes for passing a cooling air are provided in these member so as to cool the member by passing cooling air. In
FIG. 8
, reference numeral
20
is a split ring provided in the wall around the first stage moving blade, in which a plurality of arc-shaped rings split on the circumference are coupled to compose a cylindrical wall, and a cooling air hole is provided to cool by passing cooling air.
FIG. 9
is an exploded view of portion B shown in FIG.
8
and shows the split ring in detail. In
FIG. 8
, the first stage moving blade
34
is disposed between the first stage stationary blade
31
and second stage stationary blade
35
, and the split ring
20
is disposed around the circumference of the first stage moving blade
34
. In
FIG. 9
, reference numeral
21
is a cooling air hole provided in the split ring
20
. This cooling air hole
21
has an opening
21
a
inside in the upper face, and an opening
21
b
in the side face. Reference numeral
22
is an impinging plate. A cooling air inlet hole
23
is provided above the impinging plate
22
through which cooling air
50
is sent in. The cooling air
50
gets into an inner space
24
, and reaches the split ring
20
after passing through the many holes provided in the impinging plate
22
. This cooling air cools the surface of the split ring
20
, and further flows into the cooling air hole
21
through the opening
21
a
, and flows out to the outside gas passage through the opening
21
b
, thereby cooling the inside of the split ring
20
in this process.
FIG. 10
is a view when seen along the arrows C—C in FIG.
9
. This figure shows a part of the split ring
20
. The diagram shows the split ring
20
forming a part of the cylindrical structure. Many cooling air holes
21
are arranged in the cylindrical side face. The cooling air holes
21
have opening
21
b
. The inside of the split ring
20
can be cooled by passing cooling air in these holes. The split ring
20
is coupled with adjacent split rings
20
a
,
20
b
and arranged cylindrically, and grooves
26
a
,
26
b
are provided alternately at the connection area, and a seal plate
25
is inserted into the grooves
26
a
,
26
b
, thereby preventing leakage of sealing air.
FIG. 11
is a view when seen along the arrows D—D in FIG.
10
. This figure shows a state in which the seal plate
25
is inserted in the grooves at the ends as mentioned above to seal, multiple cooling air holes
21
are formed inside the split ring
20
, and the cooling air holes
21
have openings
21
a
at the surface at one side, and openings
21
b
at the side face at the other side, and the cooling air is introduced from the openings
21
a
, and flows out to the gas pass from the openings
21
b
, thereby cooling the wall of the split rings
20
.
FIG.
12
A and
FIG. 12B
are magnified views of the seal plate shown in FIG.
10
.
FIG. 12A
is a side view, and
FIG. 12B
is a view when seen along the arrows E—E in FIG.
12
A. As shown in these figures grooves
26
a
,
26
b
are provided in the mutually adjacent split rings
20
b
and
20
a
, and the seal plate
25
is inserted in these grooves. As shown in
FIG. 12A
, the portions X and Y are groove processed parts of the seal plate
25
, and cooling air holes cannot be easily provided in these portions. Consequently, cooling is not sufficient, and the high temperature gas is likely to stay in the space Z between the portions X and Y. Therefore, the portions X and Y are likely to be burnt by the high temperature gas.
FIG.
13
A and
FIG. 13B
show burnt portions X, Y shown in FIG.
12
.
FIG. 13A
is a sectional view, and
FIG. 13B
is a view when seen along the arrows F—F in FIG.
13
A. As shown in these figures, the portions X, Y are exposed to the high temperature gas, and get burnt as indicated by
50
,
51
. When this state advances, the lower ends of the grooves
26
a
,
26
b
are lost, and the seal plate
25
provided inside may slip out. It has been hence demanded to develop a cooling structure capable of preventing burning of end portions at the connection area of such split ring.
Thus, in the connection area of the conventional gas turbine split rings, it is designed to seal the connection area by the seal plate, and the end portions of such connection area in which grooves are formed for inserting the seal plate are exposed to high temperature combustion gas and burnt, or reduced in wall thickness due to high temperature oxidation, or the end portions are melted and lost, and the seal plate in the grooves may slip out.
SUMMARY OF THE INVENTION
It is an object of the present invention to present a gas turbine split ring characterized by reinforcing the cooling of the end portions for holding the seal plate at the connection area of the split ring, reducing effects of high temperature combustion gas at end portions, and preventing burning of split ring end portions, thereby extending the life of the split ring and enhancing the reliability.
According to one aspect of this invention, the adjacent end faces of the split ring are mutually changed in the peripheral direction between inner side and outer side of the gas pass, and hence are not coupled straightly. At this junction, a specific gap is provided in consideration of thermal expansion, and a seal plate is inserted therein. Therefore, the leak of the cooling air from the connection area at the inner side is prevented by the seal plate. Moreover, since the connection area has a bent gap, it increases the passage resistance of the high temperature combustion gas flowing into the gap from the inner side, so that the structure does not allow invasion of gas easily. Still more, since the oblique cooling air hole is opened in the inner wall near the inside of the connection area, the air flowing out from this opening forms a film for cooling the inner end face at the junction, thereby preventing burning of the inner end portion at the junction.
According to another aspect of this invention, the cooling air hole is opened at the end face near the inner side of the junction. Therefore, the cooling air flows out from the gap at the inner side of the connection area through this opening, which blocks the high temperature gas invading into the gap from the inner side, thereby cooling the gap in the connection area. Moreover, the seal plate is disposed at the inner side of the bent gap of the connection area. Such a seal plate increases the resistance of the passage of air leaking out through the groove in the seal plate from the outer side gap. Therefore, the cooling air hardly leaks.
Further, the other split section end face confronting the opening of the air cooling hole is cut obliquely. Therefore, the air flows out smoo

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