Power plants – Combustion products used as motive fluid – Combustion products generator
Reexamination Certificate
1999-08-09
2001-04-03
Freay, Charles G. (Department: 3746)
Power plants
Combustion products used as motive fluid
Combustion products generator
C060S737000
Reexamination Certificate
active
06209327
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the field of gas-turbine technology. It relates to a burner arrangement for a gas turbine, where the burner arrangement comprises a interior space enclosed by a casing, in which interior space at least one burner is arranged, and into which interior space in each case a jet of a gaseous medium, in particular air, is sprayed through at least two nozzle openings against the direction of flow of the burner and along the inner wall of the casing, which jets, guided by the inner wall, meet one another from opposite directions and combine to form a secondary flow flowing off perpendicularly from the inner wall.
Such a burner arrangement has been disclosed, for example, by publication EP-A2-0 692 675 (see, for example, FIG. 1 there).
2. Discussion of Background
A double-cone burner of a gas turbine, to which double-cone burner fuel is fed via a fuel lance, is shown in the publication mentioned at the beginning (e.g. in FIG. 1 there). The burner is accommodated in the interior space of a dome-like casing. Main burner air flows into the casing against the direction of flow of the burner above and below the burner, is deflected by the inner wall of the casing and then enters the burner in order to be mixed with the fuel there.
Such a flow in a casing, which flow results from two or more jets striking one another, the jets entering the casing through corresponding nozzle openings, is generally extremely sensitive to fluctuations in the total pressure of the jets. This may be illustrated with reference to FIG.
1
. In the flow arrangement
10
according to
FIG. 1
, two jets
15
,
16
are sprayed on two opposite sides through corresponding nozzle openings
13
,
14
into an interior space
11
, which is defined by a boundary wall
12
(curved in a semicircle in this example), and these jets
15
,
16
—guided by the boundary wall
12
—meet one another at an impingement point
18
and combine there to form a secondary flow
17
, which is directed perpendicularly to the boundary wall into the interior of the interior space
11
.
The velocity of the jets
15
,
16
approaches zero at the impingement point
18
. Since the wall streamlines of the two jets
15
and
16
meet at the stagnation point
18
, the total pressures of the jets
15
and
16
must also correspond there. Since the friction at the boundary wall
12
typically does not lead to a rapid change in the total pressure, the impingement point
18
will regularly lie in the vicinity of one of the two nozzle openings
13
,
14
, which produce the jets
15
,
16
. In the extreme case, one of the jets
15
,
16
may even block the nozzle opening which is intended to produce the other jet. Even in the cases in which the total pressures of the two jets are virtually the same, the position of the impingement point normally deviates greatly from the plane of symmetry which runs between the two nozzle openings.
This instability and uncertainty of such casing flows also has an effect in the case of a burner arrangement
20
as shown in FIG.
2
. The burner
21
(in this case a double-cone burner of known type of construction) is accommodated in a casing
23
in such a way as to lie in a plane of symmetry
19
. The burner
21
opens to the left into a combustion chamber
33
; it is supplied with fuel from the right via a fuel feed
32
. Formed at the top and bottom between the combustion chamber
33
and the casing
23
are nozzle openings
24
and
25
, through which combustion air (from the compressor of the gas turbine) is sprayed in the form of jets
26
,
27
into the interior space
22
enclosed by the casing
23
. The jets
26
,
27
flow toward one another along the inner wall
23
a
of the casing
23
and, after striking one another, combine to form a secondary flow
28
, which flows toward the burner
21
and enters the burner
21
laterally. As indicated in
FIG. 2
, the impingement point and thus also the secondary flow generally lie at a varying point outside the plane of symmetry, which point cannot be predetermined and may change quickly due to geometric disturbances in the arrangement and due to pressure fluctuations. As a result, the uniform operation of the burner
21
under stable combustion conditions is considerably impaired.
SUMMARY OF THE INVENTION
Accordingly, one object of the invention is to provide a novel burner arrangement in which stable flow conditions of the sprayed-in combustion air result, these flow conditions being essentially unaffected by geometric deviations and pressure fluctuations.
The object is achieved in a burner arrangement of the type mentioned at the beginning in that, to establish the impingement point of the jets, a dividing plate is placed in the flow path of the jets and arranged essentially perpendicular to the inner wall. The two jets strike the dividing plate, mounted in a fixed position, from both sides and are deflected parallel to the dividing plate into the interior space, where they are combined behind the dividing plate to form a secondary flow, which flows parallel to the dividing plate.
Depending on the arrangement of the dividing plate, the secondary flow may be produced at different points of the casing and with different directions. However, a preferred embodiment of the invention is defined in that the burner is arranged inside the casing in a plane of symmetry, in that the nozzle openings are arranged symmetrically to the plane of symmetry, and in that the dividing plate lies in the plane of symmetry.
Further embodiments follow from the dependent claims.
REFERENCES:
patent: 5699667 (1997-12-01), Joos
patent: 4436728A1 (1996-04-01), None
patent: 0252315A1 (1988-01-01), None
patent: 0692675A2 (1996-01-01), None
patent: 0742411A2 (1996-11-01), None
patent: 2422904 (1979-11-01), None
patent: 05223109 (1993-08-01), None
Fischer Jochem
Keller Jakob
Keller Vera
Muller Ulf Christian
Reiss Frank
Asea Brown Boveri AG
Burns Doane Swecker & Mathis L.L.P.
Freay Charles G.
Hayes Ed
Keller Vera
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