WO2013147632A1 - Bi-directional end cover with extraction capability for gas turbine combustor - Google Patents

Abstract

A bi-directional end cover assembly (14) for a gas turbine combustor comprising an end cover plate provided with plural nozzle supports (34), at least one fuel inlet, and at least one diluent manifold (36; 38) communicating with an annular internal passage (40) provided with plural outlet apertures (42) which open to a combustion chamber of the combustor; one or more conduits adapted, in use, to supply a diluent to the at least one diluent manifold (36; 38) and to the annular internal passage (40) in a diluent-injection mode; one or more conduits adapted, in use, to extract working fluid from the combustion chamber via the annular internal passage (40) and the at least one diluent manifold in a working-fluid-extraction mode; and control valves (46; 54) for selectively controlling flow of the diluent in the diluent-injection mode and flow of working fluid in the working-fluid-extraction mode.

Description

BI-DIRECTIONAL END COVER WITH EXTRACTION CAPABILITY

FOR GAS TURBINE COMBUSTOR BACKGROUND

[0001 ] This invention relates to a gas turbine combustor end cover and, more specifically, to a bi-directional end cover with working fluid extraction capability.

[0002] Combustors typically include one or more fuel nozzles that introduce a fuel or a mixture of fuel and air to a combustion chamber where it is ignited. In some combustors, the fuel nozzles extend through or are supported by a baffle or end cover. It is often advantageous to introduce a volume of diluent, e.g., nitrogen or steam, into the combustor to reduce NO_x and/or CO emissions and/or augment output of the combustor. Accordingly, additional diluent passages and related hardware are required within the end cover, increasing both the complexity and the cost of the end cover assembly.

[0003] There are also combustors that require separate internal manifolds for combustor working fluid extraction such as extraction exhaust gas recirculation (EGR), combustor air or any combination of air mixture with inert diluent.

[0004] It would be desirable to provide a simplified end cover assembly that accommodates both the injection and extraction functions mentioned above, but with minimal hardware and reduced cost.

BRIEF SUMMARY OF THE INVENTION

[0005] Accordingly, in one exemplary but nonlimiting embodiment, there is provided a bi-directional end cover assembly for a gas turbine combustor comprising an end cover plate provided with plural nozzle supports, at least one fuel inlet, and at least one diluent manifold communicating with an annular internal passage provided with plural outlet apertures which open to a combustion chamber of the combustor; one or more conduits adapted, in use, to supply a diluent to the at least one diluent inlet and to the annular internal passage in a diluent-injection mode; one or more

I conduits adapted, in use, to extract working fluid from the combustion chamber via the annular internal passage, and the at least one diluent manifold, in a working-fluid- extraction mode; and control valves for selectively controlling flow of the diluent in the diluent- injection mode and flow of working fluid in the working-fluid-extraction mode. [0006] In another exemplary but nonlimiting embodiment, there is provided a gas turbine combustor comprising a combustor casing defining a combustion chamber, and a bi-directional end cover assembly attached to an upstream end of the casing, the bidirectional end cover assembly including an end cover plate provided with supports for one or more nozzles, at least one fuel inlet adapted to supply fuel to the one or more nozzles, at least one diluent manifold communicating with an annular internal passage provided with plural outlet apertures which open to the combustion chamber; one or more conduits adapted, in use, to supply a diluent to the at least one diluent manifold and to the annular internal passage in a diluent-injection mode; one or more conduits that, in use, are adapted to extract working fluid from the combustion chamber via the annular internal passage in a working-fluid-extraction mode; and control valves for selectively controlling flow of diluents in the diluent-injection mode and flow of working fluid in the working- fluid-extraction mode.

[0007] In still another exemplary but nonlimiting embodiment, there is provided method of managing a flow of diluent into a combustion chamber of a gas turbine combustor and a flow of working fluid out of the combustion chamber comprising providing a combustor end cover having an internal annular passage provided with plural apertures opening to the combustion chamber; connecting one or more supply manifolds to the end cover in communication with the internal annular passage; providing a diluent- injection control valve and a working-fluid-extraction control valve in respective injection and extraction conduits in communication with the internal annular passage via the one or more supply manifolds; in a diluent-injection mode, supplying a diluent to the combustion chamber by way of the one or more inlet manifolds, the internal annular passage and the plural apertures under the control of the diluent-injection control valve, while keeping the working-fluid-extraction valve closed; and in a working-fluid- extraction mode, extracting working fluid from the combustion chamber by way of the plural apertures, the internal annular passage and the one or more supply manifolds, under the control of the working- fluid-extraction valve, while keeping the diluent injection valve closed.

[0008] The invention will now be described in detail in connection with the drawings identified below.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Fig. 1 is a partial section view through a conventional gas turbine combustor;

[0010] Fig. 2 is a partial section of a gas turbine combustor end cover construction in accordance with a first exemplary but nonlimiting embodiment of the invention in a diluent injection mode;

[001 1 ] Fig. 3 a partial section of a gas turbine combustor end cover construction as shown in Fig. 1 but in a working fluid extraction mode; and

[0012] Fig. 4 a partial section of a gas turbine combustor end cover construction in accordance with a second exemplary but nonlimiting embodiment of the invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] Shown in Fig. 1 is a representative example of a gas turbine combustor 10.

The combustor 10 includes a plurality of fuel nozzles 12 supported by an end cover assembly, or simply, end cover 14. Compressed air and fuel are directed through the end cover 14 to the plurality of fuel nozzles 12, which distribute a mixture of the compressed air and fuel into the combustion chamber 16. The combustion chamber is generally defined by a casing 18, a liner 20 and flow sleeve 22. In some embodiments, the flow sleeve 22 and the liner 20 are substantially coaxial to thereby define an annular passage 24 that may enable passage of compressor discharge air for cooling and/or entry into the combustion chamber 16 via, for example, a plurality of apertures (not shown) in the liner 20. The hot combustion gases pass through a transition piece or duct 26 to the first stage of a turbine, represented at 28. [0014] With reference to Fig. 2, re-designed end cover assembly 14 in accordance with an exemplary but nonlimiting embodiment of this invention supports the upstream ends of the nozzles 12 and includes a center nozzle manifold 30, a secondary fuel nozzle manifold 32 and diluent manifolds 36, 38. The upstream ends of the nozzles 12 are supported within recesses 34 provided in the end cover. The number and arrangement of nozzles may vary and is not a limiting factor with respect to the invention described herein.

[0015] The diluent manifolds 36, 38 communicate with an internal annular passage

40 which enables the diluent to circulate about the end cover and to exit via a plurality of circumferentially-arranged outlets 42 that open into the combustion chamber.

[0016] In a diluent- injection mode, one or more diluents such as steam or Nitrogen are supplied to the end cover 14 by means of a supply line or conduit 44 and a diluent- injection control valve 46 located along the supply conduit 44. The conduit 44 along with branch conduits 48, 50, supply the one or more diluents directly to the diluent manifolds 36, 38 which connect to the annular internal passage 40 for introduction into the combustion chamber 16 via the circumferentially-spaced, annular array of outlet apertures or orifices 42.

[0017] An extraction conduit 52 branches off from the diluent conduit 44 at a location between the valve 46 and the branch conduit 48. A working-fluid- extraction control valve 54 is located along the extraction conduit 52.

[0018] With reference now to Fig. 3, when diluent injection is not required, the same end cover internal annular passage 40 or and conduits 44, 48 and 50 are used for outboard extraction of combustor working fluid (for example, EGR, combustor air or any combination of air mixture with inert gases). Thus, the flow direction is reversed through the apertures 42, internal annular passage 40, manifolds 36, 38 and conduits 44, 48 and 50. During extraction, the diluent-injection control valve 46 is closed, forcing the extracted fluid to flow into the extraction conduit 52, with extraction valve 54 now open to control the flow of extracted fluid to an extraction delivery manifold (not shown). [0019] In reversing the mode of operation from the diluent- injection to the working-fluid-extraction mode, the working fluid is driven out of the combustion chamber and into the passage 40 and manifold 36, 38 by the pressure difference between the combustor chamber and ambient pressure (usually about 10-20 atm). [0020] The advantages of the dual use of the inert injection hardware includes a wider combustor operability envelope; advanced durability characteristics of the combustor hardware; control over flame temperature and emissions; and the cost and reliability benefit of not having extra accessories to manage extraction flows.

[0021 ] It will be appreciated that the number of supply pipes or conduits may vary depending on velocities and modes of operation. In addition, the internal passage 40 which is described as annular, may be substantially continuous or it could be segmented. If a segmented passage 40 is used, some segments may be reserved for injection and the remaining segments reserved for simultaneous extraction. This arrangement as shown in Fig. 4 where the manifold 40 is divided into upper and lower segments (e.g., each segment extending substantially 180°). Here, the lower manifold segment 56 is reserved for use in the diluent- injection mode, with diluent supplied to the lower manifold segment via manifold 38 and conduct 60, under the control of valve 46. At the same time, the upper manifold segment 58 is reserved for working-fluid extraction with the fluid exiting the segment 58, manifold 36 and conduit 62, under the control of the working-fluid-extraction valve 54. While this arrangement is somewhat less advantageous, at least in terms of hardware savings, it provides other advantages, particularly in that it permits diluent injection and working fluid extraction to occur simultaneously rather than sequentially.

[0022] While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

WHAT IS CLAIMED IS:

1. A bi-directional end cover assembly for a gas turbine combustor comprising:

an end cover plate provided with plural nozzle supports, at least one fuel inlet, and at least one diluent manifold communicating with an annular internal passage provided with plural outlet apertures which open to a combustion chamber of the combustor;

one or more conduits adapted, in use, to supply a diluent to said at least one diluent manifold and to said annular internal passage in a diluent-injection mode;

one or more conduits adapted, in use, to extract working fluid from the combustion chamber via said annular internal passage and said at least one diluent manifold in a working-fluid-extraction mode; and

control valves for selectively controlling flow of the diluent in said diluent- injection mode and flow of working fluid in said working-fluid-extraction mode.

2. The bi-directional end cover assembly of claim 1 wherein said at least one diluent manifold comprises at least two diluent inlet manifolds.

3. The bi-directional end cover assembly of claim 1 wherein said annular internal passage is comprised of at least two arcuate segments.

4. The bi-directional end cover assembly of claim 3 wherein one of said arcuate segments is reserved for use in said diluent-injection mode and another of said arcuate segments is reserved for use in said working-fluid-extraction mode.

5. The bi-directional end cover assembly of claim 1 wherein said at least one diluent manifold comprises a pair of diluent manifolds; and wherein said control valves comprise a diluent- injection valve located in one of said conduits upstream of said pair of diluent manifolds.

6. The bi-directional end cover assembly of claim 5 wherein a fluid-extraction valve is located in an extraction branch conduit located upstream of said pair of diluent manifolds and downstream of said diluent-injection valve.

7. The bi-directional end cover assembly of claim 1 wherein said plural outlet apertures are arranged in an annular array about a center axis of said end cover plate.

8. The bi-directional end cover assembly of claim 3 wherein said plural outlet apertures are arranged in an annular array about a center axis of said end cover plate, and each arcuate segment is provided with a predetermined fraction of said outlet apertures.

9. A gas turbine combustor comprising: a combustor casing defining a combustion chamber, and a bi-directional end cover assembly attached to an upstream end of said casing, said bi-directional end cover assembly including an end cover plate provided with supports for one or more nozzles, at least one fuel inlet adapted to supply fuel to the one or more nozzles, at least one diluent manifold communicating with an annular internal passage provided with plural outlet apertures which open to said combustion chamber;

one or more conduits adapted, in use, to supply a diluent to said at least one diluent manifold and to said annular internal passage in a diluent- injection mode; one or more conduits that, in use, are adapted to extract working fluid from said combustion chamber via said annular internal passage in a working-fluid-extraction mode; and

control valves for selectively controlling flow of diluents in said diluent-injection mode and flow of working fluid in said working-fluid-extraction mode.

10. The gas turbine combustor of claim 9 wherein said annular internal passage is comprised of at least two arcuate segments.

1 1 . The gas turbine combustor of claim 10 wherein one of said arcuate segments is reserved for use in said diluent-injection mode and another of said segments is reserved for use in said working-fluid-extraction mode.

12. The gas turbine combustor of claim 9 wherein said at least one diluent manifold comprises a pair of diluent manifolds; and wherein said control valves comprise a diluent injection valve located in one of said conduits upstream of said pair of diluent manifolds.

13. The gas turbine combustor of claim 12 wherein a fluid extraction valve is located in an extraction branch conduit located upstream of said pair of diluent manifolds and downstream of said diluent injection valve.

14. The gas turbine combustor of claim 9 wherein said plural outlet apertures are arranged in a circumferentially-spaced, annular array.

15. The gas turbine combustor of claim 10 wherein said pair of arcuate segments comprises a pair of 1 80° segments.

16. A method of managing a flow of diluent into a combustion chamber of a gas turbine combustor and a flow of working fluid out of the combustion chamber comprising: (a) providing a combustor end cover having an internal annular passage provided with plural apertures opening to the combustion chamber;

(b) connecting one or more supply manifolds to the end cover in communication with said internal annular passage;

(c) providing a diluent injection control valve and a working fluid extraction valve in respective injection and extraction conduits in communication with said internal annular passage via said one or more supply manifolds;

(d) in a diluent-injection mode, supplying a diluent to said combustion chamber by way of said one or more supply manifolds, said internal annular passage and said plural apertures under the control of said diluent-injection control valve, while keeping said working-fluid-extraction valve closed; and

(e) in a working-fluid-extraction mode, extracting working fluid from said combustion chamber by way of said plural apertures, said internal annular passage and said one or more supply manifolds under the control of said working-fluid- extraction valve, while keeping said diluent-injection valve closed.

17. The method of claim 16 wherein said annular internal passage is comprised of at least two arcuate segments.

18. The method of claim 17 wherein one of said arcuate segments is reserved for use in said diluent-injection mode and another of said segments is reserved for use in said working-fluid-extraction mode.

19. The method of claim 16 wherein said one or more supply manifolds comprise a pair of supply manifolds; and wherein said diluent- injection valve is located in one of said conduits upstream of said pair of supply manifolds.

20. The method of claim 19 wherein said working-fluid- extraction valve is located in an extraction branch conduit located upstream of said pair of supply manifolds and downstream of said diluent-injection valve.