Power plants – Combustion products used as motive fluid – Combustion products generator
Reexamination Certificate
2000-05-31
2001-11-06
Freay, Charles G. (Department: 3746)
Power plants
Combustion products used as motive fluid
Combustion products generator
C431S264000
Reexamination Certificate
active
06311475
ABSTRACT:
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The invention relates to a device for igniting a combustion in a combustion chamber of a gas turbine. The device has a housing with an end piece and a head piece. An ignition conductor extends between the end piece and the head piece. A spark plug is disposed in the end piece of the housing. A gas conduit leads to an ignition head in the housing and an air feed line is provided to the interior of the housing.
A device of this kind has been disclosed by Published, Non-Prosecuted German Patent Application DE 43 20 429 A1. In this document, the gas conduit serving as an ignition conductor is in direct contact with the ignition air. This must therefore be absolutely dry and free from oil, but this is generally difficult to achieve. The insulation is effected in part by use of ceramic pins which break easily under stress, e.g. during assembly, or in the event of pulsation during operation, leading to spark-overs in the device, which is also referred to as an ignition torch.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a device for igniting a combustion in a combustion chamber of a gas turbine that overcomes the above-mentioned disadvantages of the prior art devices of this general type, which avoids contact between the ignition conductor and the ignition air and failure due to damage from the ceramic material, and improves the quality of the overall ignition.
With the foregoing and other objects in view there is provided, in accordance with the invention, a device for igniting a combustion in a combustion chamber of a gas turbine, including:
a housing having an end piece, a head piece and an interior formed therein;
an ignition conductor extending between the end piece and the head piece;
a spark plug disposed in the end piece;
an ignition head disposed in the housing;
a gas conduit leading to the ignition head, the ignition conductor and the gas conduit running parallel to one another within the housing;
an air feed line leading to the interior of the housing;
a protective sleeve surrounding the ignition conductor and forming an annular space between the ignition conductor and the protective sleeve, the protective sleeve having an end projecting into the head piece;
a ceramic material filling the annular space and fixed relative to at least one of the ignition conductor and the protective sleeve; and
an annular disc serving as an ignition electrode mounted on the end of the protective sleeve projecting into the head piece.
Accordingly, the ignition conductor and the gas conduit run parallel to one another within the housing. The ignition conductor is surrounded by the protective sleeve. The annular space between the ignition conductor and the protective sleeve is filled with a ceramic material that is fixed relative to the ignition conductor and/or the protective sleeve. An annular disc serving as an ignition electrode is mounted on that end of the protective sleeve that projects into the head piece.
The ignition conductor is thus completely encased by the ceramic material and is, for example, fixed by adhesive bonding. If the ceramic material breaks, this does not impair functionality. Fragments of the ceramic material cannot fall into the combustion chamber since the disc serving as an ignition electrode prevents this. The ignition conductor is completely insulated from the ignition air and the ignition air therefore has to meet lower quality requirements, something that contributes to an additional reduction in costs in the preparation of the ignition air.
The gas conduit and the protective sleeve have a plurality of spacers configured as sliding discs. At least some of the sliding discs are connected rigidly to the gas conduit and/or the protective sleeve. The protective sleeve is likewise connected rigidly to the ignition head, while the ignition head is configured in such a way as to be displaceable relative to the head piece.
Since the rigid connection between the internal components of the device is achieved by welding or brazing, they cannot become detached due to vibration. The relevant components are configured in such a way that relative displacement is possible to allow compensation for thermal expansion.
Placing a thermocouple in the interior of the head piece results in that it is always possible to detect the ignition flame immediately. This measure also makes it possible to monitor the failure of an ignition torch.
In accordance with a feature of the invention, the spark plug has a pick-up, and the ignition conductor has an end facing towards the spark plug and projects into the pick-up of the spark plug and the ignition conductor can be moved in an axial direction relative to the pick-up.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a device for igniting a combustion in a combustion chamber of a gas turbine, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
REFERENCES:
patent: 2937296 (1960-05-01), Logan
patent: 3319130 (1967-05-01), Betteridge
patent: 5491972 (1996-02-01), Bretz et al.
Behnke Klaus
Bohtz Christian
Heintz Gerolf
Leonhard Mario
Molsen Jens
ABB Patent GmbH
Freay Charles G.
Greenberg Laurence A.
Lerner Herbert L.
Stemer Werner H.
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