Power plants – Combustion products used as motive fluid
Reexamination Certificate
1999-08-17
2001-06-26
Freay, Charles G. (Department: 3746)
Power plants
Combustion products used as motive fluid
C060S740000, C029S455100
Reexamination Certificate
active
06250062
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention generally relates to gas turbine combustors and, more particularly, is concerned with a fuel nozzle centering device and method for gas turbine combustors.
As depicted in
FIGS. 1
to
3
, a prior art gas turbine generally includes a combustor
10
having a main combustion chamber
12
and one or more burners
14
attached to the main combustion chamber
12
. Compressed air enters the burner
14
from the left and flows to the right through the combustor
10
. Air is provided by a compressor (not shown) and may be reversed flowed over the combustor
10
before entering the burner
14
. While only one burner
14
is shown for clarity of illustration, a plurality of burners
14
is preferably used. Typically, five or six burners are arranged in a circular array on the main combustion chamber
12
.
The main combustion chamber
12
includes a liner
16
having an upstream end
16
A and an opening
18
defined in the liner
16
by an annular collar
20
attached to the upstream end
16
A of the liner
16
. The burner
14
typically includes a cylindrical flow tube (not shown) and a fuel nozzle
22
concentrically disposed within the flow tube. The fuel nozzle
22
includes a cylindrical hub
24
, an annular flange
26
interconnected with and extending circumferentially around the hub
24
, and a tip
28
interconnected with and disposed downstream from the hub
24
. The fuel nozzle flange
26
defines a plurality of through-holes
30
which are circumferentially spaced apart from one another. The combustor
10
also includes a cover
32
and a plurality of bolts
34
. The cover
32
has a plurality of holes
36
defined therein being alignable with the holes
30
of the fuel nozzle flange
26
. The bolts
34
are inserted through the through-holes
30
of the fuel nozzle flange
26
and into the holes
36
of the cover
34
and thereby removably secure the fuel nozzle flange
26
and combustor cover
32
to one another. The fuel nozzle tip
28
has an outer periphery
38
where it is assembled into the liner collar
20
.
Due to many stack-up tolerances involved in assembling fuel nozzles of burners into the liner of the main combustion chamber, fuel nozzle misalignment is commonplace and causes a redundancy in liner head end support by sharing the support load between the fuel nozzle and liner stops (not shown). Operational experience and analysis has shown that this type of system creates an environment where dynamics are higher and part wear is increased. In the current system, fuel nozzles are assembled into liner collars through a complex assembly of parts. To allow for the stack-up of tolerances, clearances between the parts, especially at the bolts, is necessary. Because of this, misalignment of the fuel nozzle often occurs.
Various devices and methods have been developed over the years toward providing a solution of the aforementioned problem of misalignment of the fuel nozzle. The primary devices and methods employed in the industry have been the use of floating liner collars
40
, as shown in
FIG. 2
, and of a body bound arrangement, as shown in FIG.
3
. The floating liner collar
40
makes up for fuel nozzle misalignment by allowing the liner collar to “float” through a predetermined clearance. While this device and method has been somewhat satisfactory, it is expensive due to its complexity and has been prone to create additional wear problems, particularly in the liner collar itself. The body bound arrangement usually replaces three of the bolt through-holes with tapered bolts
42
that attempt to center the fuel nozzle. After time, however, the bolts or holes become worn and the same misalignment problems arise. Further, due to its complexity, this design can be difficult and expensive for retrofit applications.
Consequently, a need still exists for an innovation which will provide a solution to the aforementioned problems in the prior art without introducing any new problems in place thereof.
SUMMARY OF THE INVENTION
The present invention provides a fuel nozzle centering device and method for gas turbine combustors designed to satisfy the aforementioned need. The fuel nozzle centering device and method alleviate fuel nozzle contact such that system dynamics are reduced, part wear is reduced and overall combustor life is extended.
In an exemplary embodiment of the present invention, a gas turbine combustor comprises a main combustor chamber having a liner and an annular collar mounted to the liner so as to define an opening therethrough, at least one burner attached to the main combustor chamber and having a fuel nozzle mounted adjacent to the liner with a tip of the fuel nozzle disposed through the opening of the annular collar of the main combustor chamber and an outer periphery of the tip disposed within and adjacent to the annular collar, and a fuel nozzle centering device mounted to the tip of the fuel nozzle and disposed between the outer periphery of the fuel nozzle tip and the annular collar of the liner, the device including a sacrificial body of material contacting the liner collar and spacing the fuel nozzle tip radially inwardly from the liner collar such that the fuel nozzle tip is prevented from contacting the liner collar during assembling of the fuel nozzle of the burner to the liner of the main combustion chamber, the sacrificial body of material being at least partially wearable away upon initial operation of the gas turbine combustor such that the sacrificial body of material will diminish in quantity and thereby reduce contact with the liner collar during further operation of the gas turbine combustor so that the fuel nozzle tip will remain spaced from and substantially out of contact with the liner collar of the main combustion chamber during continued operation of the gas turbine combustor. The body of sacrificial material can have a substantially annular configuration and extend around the outer periphery of the fuel nozzle tip of the burner. The body of material may be in the form of a bead, tape or a wire. The device can include a plurality of bodies of the material having substantially the same sizes and being are spaced apart such as at equal distances from one another.
In another exemplary embodiment of the present invention, a method for centering a fuel nozzle of a burner in a gas turbine combustor comprises the steps of providing at least one and, preferably, a plurality of bodies of a substantially wearable and sacrificial material, mounting the bodies to an outer periphery of a tip of a fuel nozzle of a burner for a gas turbine combustor, assembling the fuel nozzle with its tip extending through an opening of an annular collar attached to a liner of a main combustion chamber of the combustor, and preventing the fuel nozzle tip of the burner from coming into contact with the liner collar of the main combustion chamber during the assembling step by the bodies contacting the liner collar of the main combustion chamber and spacing the fuel nozzle tip of the burner from the liner collar. The method further comprises the step of wearing away the bodies at least partially and, preferably, substantially upon initial operation of the gas turbine combustor such that the bodies will reduce contact with the liner collar of the main combustion chamber during further operation of the combustor and the fuel nozzle tip of the burner will remain spaced from and out of contact with the liner collar of the main combustion chamber during operation of the combustor.
These and other features and advantages of the present invention will become apparent to those skilled in the art upon a reading of the following detailed description when taken in conjunction with the drawings wherein there is shown and described an illustrative embodiment of the invention.
REFERENCES:
patent: 3853273 (1974-12-01), Bahr et al.
patent: 4656713 (1987-04-01), Rosa et al.
patent: 5408830 (1995-04-01), Lovett
patent: 5471840 (1995-12-01), Lovett
patent: 5518395 (1996-05-01), Maughan
patent: 5676538 (1997-10-01), Lovett
Cromer Robert Harold
Lawen, Jr. James Louis
Mohammed-Fakir Abdul-Azeez
Wiersma Henry Joe
Freay Charles G.
Gartenberg Ehud
General Electric Company
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