Power plants – Combustion products used as motive fluid – Multiple fluid-operated motors
Reexamination Certificate
2000-12-27
2004-08-10
Freay, Charles G. (Department: 3746)
Power plants
Combustion products used as motive fluid
Multiple fluid-operated motors
C060S806000, C415S114000, C415S175000
Reexamination Certificate
active
06772581
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a gas turbine and more particularly to a gas turbine in which a blade ring, especially of first and second stages, is improved in shape so as to have less thermal influence and is cooled with less thermal expansion and uniform deformation by steam whose temperature, pressure and flow rate are controlled, so that a clearance at a moving blade tip is reduced in operation, thereby enhancing gas turbine performance.
2. Description of the Prior Art
FIG. 20
is a cross sectional view showing an interior of a representative gas turbine in the prior art. In
FIG. 20
, numeral
100
designates an outlet of a combustor transition piece, from which a high temperature combustion gas flows out. Numeral
101
designates a gas path, in which four stages of stationary blades
1
C,
2
C,
3
C,
4
C are arranged in an axial direction of the turbine. The stationary blades
1
C,
2
C,
3
C,
4
C are connected fixedly to blade rings
102
,
103
,
104
,
105
, respectively, via respective outer shrouds. Each of the stationary blades
1
C,
2
C,
3
C,
4
C includes a plurality of blades arranged in a circumferential direction of the turbine along respective inner walls of the blade rings
102
,
103
,
104
,
105
. Also, moving blades
1
S,
2
S,
3
S,
4
S are arranged in the axial direction alternately with the stationary blades
1
C,
2
C,
3
C,
4
C and each of the moving blades
1
S,
2
S,
3
S,
4
S is connected fixedly to a rotor
200
and includes a plurality of blades arranged in the circumferential direction around the rotor
200
.
In the gas turbine of the above-mentioned construction, cooling of the blade is usually done by air such that the stationary blade is fed with cooling air from the blade ring side and the moving blade is fed with cooling air from the rotor side. Along with recent higher temperature gas turbines, however, is a tendency to employ a cooling system using steam. Also, at the time of start-up of the gas turbine, while there is maintained a predetermined clearance between a moving blade tip and a blade ring, the blade ring is still cold to shrink in the rise time and, on the other hand, the rotor and the moving blade are heated earlier. Hence, the clearance at the moving blade tip becomes smaller and a risk of contact in operation becomes higher. Accordingly, the clearance must be set appropriately taking this risk into consideration. If this clearance is too broad, it will reduce the gas turbine performance. Thus to make the clearance between the moving blade tip and the blade ring as small as possible is an effective means to enhance the gas turbine performance. But the present status is that such a countermeasure is not sufficiently established yet in the field of the industrial gas turbine.
As mentioned above, in the conventional industrial gas turbine, it is usual that cooling air is led into the gas turbine stationary blade, moving blade, rotor, etc. for cooling thereof. But, in the recent tendency to employ a higher temperature gas turbine, a steam cooling system is being used in place of the air cooling system. In such a gas turbine, the clearance between the moving blade tip and the blade ring changes due to thermal influences in the operation, beginning from the start-up time. The predetermined clearance at the start-up time becomes the minimum clearance state caused by a thermal elongation difference between the blade ring and the moving blade in the rise time, so that contact may arise, inviting a dangerous state unless an appropriate setting of the clearance is ensured. Also, if the clearance is too large in operation, it will invite a reduction in the gas turbine performance, so the appropriate setting of the tip clearance of the moving blade becomes necessary. For this purpose, it is preferable to make the tip clearance less changeable by heat as well as to make the tip clearance optimally controlled so as not to cause contact but, while such control is being variously studied, it is the present status that a sufficient art therefor is not established yet in the field of the industrial gas turbine.
SUMMARY OF THE INVENTION
In view of the mentioned problem in the prior art, it is an object of the present invention to provide a gas turbine in which a gas turbine blade ring is improved in structural shape so as to have less thermal influence and to have the blade ring made with a cooling system using steam in which the temperature, pressure and flow rate are controlled so that a clearance between a moving blade tip and the blade ring may be optimally set.
In order to achieve the mentioned object, the present invention provides the following (1) to (15):
(1) A gas turbine comprises a moving blade and a blade ring confronting a tip of the moving blade. A cooling passage is provided in the blade ring and an auxiliary boiler and a steam supply source connecting to a steam turbine bottoming cycle are connected to the cooling passage. Steam of the auxiliary boiler or the steam supply source flows into the cooling passage for cooling the blade ring and the steam having cooled the blade ring is recovered. Accordingly, a clearance between the tip of the moving blade and the blade ring is reduced.
(2) A gas turbine comprises a moving blade and a blade ring confronting a tip of the moving blade as well as a combustor and a transition piece contained in the combustor. A cooling passage is provided in the blade ring so that steam of a steam supply source flows into the cooling passage for cooling the blade ring and the steam having cooled the blade ring is flown into the transition piece via a combustor transition piece connection portion for cooling a wall interior of the transition piece. The steam having cooled the wall interior of the transition piece is recovered into the steam supply source. Accordingly, a clearance between the tip of the moving blade and the blade ring is reduced.
(3) A gas turbine comprises a moving blade and a blade ring confronting a tip of the moving blade as well as a combustor and a transition piece contained in the combustor. A cooling passage is provided in the blade ring so that steam of a steam supply source flows in parallel into the cooling passage for cooling the blade ring and into the transition piece via a combustor transition piece connection portion for cooling a wall interior of the transition piece. The steam having cooled the blade ring and the wall interior of the transition piece is recovered into the steam supply source. Accordingly, a clearance between the tip of the moving blade and the blade ring is reduced.
(4) A gas turbine comprises a first stage stationary blade and a first stage moving blade and a blade ring confronting a tip of the first stage moving blade as well as a combustor and a transition piece contained in the combustor. A blade ring cooling passage is provided in the blade ring and a stationary blade cooling passage is provided in the first stage stationary blade so as to connect to the blade ring cooling passage. Steam of a steam supply source flows into the blade ring cooling passage for cooling the blade ring and the steam having cooled the blade ring flows into the stationary blade cooling passage for cooling the first stage stationary blade. The steam having cooled the first stage stationary blade flows into the transition piece via a combustor transition piece connection portion for cooling a wall interior of the transition piece and the steam having cooled the wall interior of the transition piece is recovered into the steam supply source. Accordingly, a clearance between the tip of the first stage moving blade and the blade ring is reduced.
(5) A gas turbine comprises a first stage stationary blade, a first stage moving blade, a blade ring confronting a tip of the first stage moving blade as well a combustor and a transition piece contained in the combustor. A blade ring cooling passage is provided in the blade ring and a stationary blade cooling passage is provided in the first stage stationary blad
Akagi Kouichi
Hashimoto Shinya
Magoshi Ryotaro
Morimoto Hitoshi
Ojiro Yasuhiro
Freay Charles G.
Mitsubishi Heavy Industries Ltd.
Wenderoth , Lind & Ponack, L.L.P.
LandOfFree
Gas turbine cooling passages for blade rings, combustor... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Gas turbine cooling passages for blade rings, combustor..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Gas turbine cooling passages for blade rings, combustor... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3356649