Power plants – Combustion products used as motive fluid – Combined with regulation of power output feature
Patent
1997-09-17
1999-11-23
Thorpe, Timothy S.
Power plants
Combustion products used as motive fluid
Combined with regulation of power output feature
60 3931, 60 3937, F02C 720
Patent
active
059878797
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a spring seal device for connecting an inner tube and a tail tube in a combustor for a gas turbine etc.
2. Description of the Prior Art
FIG. 7 is a schematic cross sectional view of a prior art gas turbine combustor. Fuel, together with air from a compressor, is burnt in an inner tube 1 and a tail tube 2 provided in a turbine cylinder 6 to generate a high temperature combustion gas, which combustion gas is supplied into the turbine for driving it.
FIG. 8 is an enlarged cross sectional view of the combustor portion. As shown there, the combustor has a structure constructed by the inner tube 1 and the tail tube 2 mainly for a purpose of absorbing a thermal deformation. A spring seal 3, 4 is provided mainly for preventing air leakage from between the inner tube 1 and the tail tube 2, which spring seal is one kind of a plate spring for preventing air leakage from between the inner tube 1 and the tail tube 2 even if there occurs a thermal deformation. Said spring seal also functions to increase vibration damping of the structural system.
In FIGS. 9 to 11, a prior art seal spring portion is shown enlargedly. The spring seal is of a double structure of an outer seal plate 3 and an inner seal plate 4 in which, at an end portion of the seal plate, the inner seal plate 4 is overlapped on a cut-out portion of the outer seal plate 3, as shown in FIG. 10, so that a leakage from the cut-out portion of the outer seal plate 3 is prevented by the inner seal plate 4. Also, a stopper 9 is provided for restricting a deformation of the seal plate caused by a thermal expansion.
In the gas turbine combustor, there occurs a large differential temperature between the ordinary temperature during operation stop and a temperature of approximately 1,000.degree. C. during operation, so that a large thermal deformation occurs both in the axial direction and in the radial direction. While several tens times of starts and stops of the gas turbine are repeated, there progresses a permanent settling gradually of the spring seal which had been of a predetermined dimension at the time of inspection so as not to return to the original state and a gap is sometimes generated between the tail tube 2 and the spring seal 3, 4.
If air leaks through said gap from within the turbine cylinder into the combustor, a fuel-air ratio (ratio of fuel to air) in the combustor varies and a combustion condition varies, which often gives an unfavorable influence on NO.sub.x generation and combustion vibration.
Also, a fluid flowing through said gap causes a self-exciting vibration due to so called a clearance flow and the spring seal is caused to vibrate furiously so that there arises a fear of damage of the spring seal. And if a fraction of the spring seal plunges into the combustor, there is considered a possibility of a large accident, such as damage of turbine blades.
It is therefore an object of the present invention to provide a spring seal device for a combustor in which a spring seal for connecting an inner tube and a tail tube of the combustor is constructed so as not to cause an air leakage due to an aged deterioration thereof.
SUMMARY OF THE INVENTION
In order to solve said problems in the prior art, the present invention provides a spring seal device for a combustor of a gas turbine etc. which is constructed to comprise a spring seal guide which pinches an end portion of a spring seal between itself and an outer wall of an inner tube of the combustor or between itself and an inner wall of a tail tube of the combustor to connect said inner tube and said tail tube.
The other end portion of the spring seal which is opposite to that pinched between the spring seal guide and the outer wall of the inner tube or between the spring seal guide and the inner wall of the tail tube is fixed to the inner wall of the tail tube or to the outer wall of the inner tube by an appropriate fixing means.
The spring seal may consist of an inner spring seal and an outer spring seal, sa
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patent: 3344601 (1967-10-01), Mieczkowski, Jr.
patent: 3759038 (1973-09-01), Scalzo et al.
patent: 4640092 (1987-02-01), Coburn et al.
patent: 4688378 (1987-08-01), Harris
patent: 4805397 (1989-02-01), Barbier et al.
patent: 4912922 (1990-04-01), Maclin
patent: 5749218 (1998-05-01), Cromer et al.
Gartenberg Ehud
Mitsubishi Jukogyo Kabushiki Kaisha
Thorpe Timothy S.
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