APPARATUS AND METHOD FOR MODIFYING A COMBUSTOR NOZZLE

Abstract

A combustor nozzle includes a nozzle body that defines a cavity. An orifice in the nozzle body provides fluid communication from the cavity through the nozzle body. A movable barrier proximate to the orifice has a first position in which the movable barrier at least partially obstructs the orifice. A method for supplying fuel to a combustor includes flowing fuel through an orifice in a nozzle, determining a reactivity of the fuel, and adjusting an effective cross sectional area of the orifice based on the reactivity of the fuel.

Description

FIELD OF THE INVENTION

The present invention generally involves an apparatus and method for modifying a combustor nozzle. In particular, embodiments of the present invention include a nozzle that can be adjusted to operate with fuels having different reactivity levels.

BACKGROUND OF THE INVENTION

Combustors are widely used in commercial operations. For example, a typical gas turbine includes a compressor that supplies a compressed working fluid to at least one combustor. The combustor mixes fuel with the compressed working fluid and ignites the mixture to produce combustion gases having a high temperature and pressure. The combustion gases exit the combustor and flow to a turbine where they expand to produce work.

Various fuels may be supplied to the combustor for combustion. For example, the combustor may be designed to operate using blast furnace gas, coke oven gas, natural gas, vaporized liquefied natural gas (LNG), propane, hydrogen, or combinations thereof. Each fuel type generally has a different reactivity for combustion. In addition, the reactivity may vary among fuels of the same type, depending on various factors such as the fuel supplier, purity, temperature, addition of diluents, etc. Changes in the fuel may change the operation and/or performance of various components in the gas turbine. For example, a change in the reactivity of the fuel may change the pressure, temperature, and output of the combustor. Therefore, it may be desirable to adjust the combustor, and specifically the nozzles in the combustor, to accommodate fuels having different reactivity levels.

Various efforts have been made to design and operate combustors with different reactivity fuels. For example, the operating limits of the combustors may be adjusted based on the reactivity of the fuel. However, this solution may result in reduced operating limits for the combustors or other equipment associated with the gas turbine. Another solution for operating combustors with different reactivity fuels is to shut down the combustor and replace one or more nozzles with substitute nozzles having different sized fuel orifices. However, this method requires interruption of the service provided by the gas turbine as well as an inventory of substitute nozzles. Interruption of the service provided by the gas turbine obviously results in unplanned and unwanted outages, and the inventory of substitute nozzles increases the operating costs for the gas turbine. As a result, an improved nozzle that can be adjusted to operate with different reactivity fuels would be desirable.

BRIEF DESCRIPTION OF THE INVENTION

Aspects and advantages of the invention are set forth below in the following description, or may be obvious from the description, or may be learned through practice of the invention.

One embodiment of the present invention is a combustor nozzle that includes a nozzle body that defines a cavity. An orifice in the nozzle body provides fluid communication from the cavity through the nozzle body. A movable barrier proximate to the orifice has a first position in which the movable barrier at least partially obstructs the orifice.

Another embodiment of the present invention is a combustor nozzle that includes a nozzle body that defines a cavity. An orifice in the nozzle body provides fluid communication from the cavity through the nozzle body. A removable insert in the orifice reduces effective cross sectional area of the orifice.

The present invention also includes a method for supplying fuel to a combustor. The method includes flowing fuel through an orifice in a nozzle, determining a reactivity of the fuel, and adjusting an effective cross sectional area of the orifice based on the reactivity of the fuel.

Those of ordinary skill in the art will better appreciate the features and aspects of such embodiments, and others, upon review of the specification.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including the best mode thereof to one skilled in the art, is set forth more particularly in the remainder of the specification, including reference to the accompanying figures, in which:

FIG. 1 is a simplified cross-section of a combustor known in the art;

FIG. 2 is a simplified cross-section of a nozzle according to one embodiment of the present invention;

FIG. 3 is a simplified cross-section of a nozzle according to an alternate embodiment of the present invention;

FIG. 4 is a perspective view of a removable insert according to one embodiment of the present invention;

FIG. 5 is a perspective view of a removable insert according to a second embodiment of the present invention; and

FIG. 6 is a perspective view of a removable insert according to a third embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to present embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and description have been used to refer to like or similar parts of the invention.

Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present invention without departing from the scope or spirit thereof. For instance, features illustrated or described as part of one embodiment may be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

Various embodiments of the present invention provide a nozzle for a combustor that may be used with different reactivity fuels. The nozzle generally includes one or more orifices for flowing fuel into a combustion chamber, and the cross sectional area of the one or more orifices may be increased or decreased according to the reactivity of the fuel. As a result, the nozzle may be adjusted to be used with fuels having different reactivity levels.

FIG. 1 provides a simplified cross-section of a combustor 10 within the scope of the present invention. Although the combustor 10 illustrated in FIG. 1 is suitable for use in a gas turbine system, one of ordinary skill in the art will readily appreciate that the embodiments of the present invention described herein are not limited to a combustor used in a gas turbine system, unless specifically recited in the claims. A casing 12 may surround the combustor 10 to contain a compressed working fluid. Nozzles may be arranged in an end cover 16, for example, with primary nozzles 18 radially arranged around a secondary nozzle 20, as shown in FIG. 1. A liner 22 downstream of the nozzles 18, 20 may define an upstream chamber 24 and a downstream chamber 26 separated by a throat 28. The compressed working fluid may flow between the casing 12 and the liner 22 to the nozzles 18, 20. The nozzles 18, 20 mix fuel with the compressed working fluid, and the mixture flows from the nozzles 18, 20 into the upstream 24 and downstream 26 chambers where combustion occurs.

FIG. 2 provides a simplified cross-section of a nozzle 30 installed in the end cover 16 of the combustor 10 according to one embodiment of the present invention. As shown, the nozzle 30 generally includes a nozzle body 32 that defines a cavity 34 inside the nozzle 30 and one or more orifices 36 in the nozzle body 32 that provide fluid communication from the cavity 34 through the nozzle body 32. The nozzle 30 may further include a shroud 38 surrounding the nozzle body 32 with one or more swirler vanes 40 radially arranged between the shroud 38 and the nozzle body 32. A supply of fuel 42 connected to the nozzle 30 supplies fuel to the cavity 34. The fuel then flows through the one or more orifices 36, and the swirler vanes 40, if present, swirl the fuel entering the upstream chamber 24 prior to combustion.

As shown in FIG. 2, the nozzle may further include one or more movable barriers 44 proximate to the one or more orifices 36. The movable barrier 44 generally includes a distal end 46 having any geometric shape. For example, the distal end 46 may comprise a cylinder, circle, square, triangle, or other geometric shape. The movable barrier 44 may be located completely inside the cavity 34, as shown in FIG. 2. In alternate embodiments, the movable barrier 44 may be located partially inside the cavity 34, with the distal end 46 extending through the orifice 36.

The movable barrier 44 has a first position and a second position. In the first position, the distal end 46 of the movable barrier 44 is closer to the orifice 36 to obstruct the orifice 36 and/or reduce the effective cross sectional area of the orifice 36. As used herein, the effective cross sectional area of the orifice 36 is the total area through which the fuel they flow from the cavity 34 into the upstream chamber 24. For example, in the first position, the distal end 46 of the movable barrier 44 may be close enough to the orifice 36, or even inside the orifice 36, so as to reduce the effective cross sectional area of the orifice 36, thereby reducing the flow rate of fuel from the cavity 34, through the orifice 36, and into the combustion chamber 24. In the second position, the distal end 46 of the movable barrier 44 may be further from the orifice 36 so as to increase the effective cross sectional area of the orifice 36. For example, in the second position, the distal end 46 of the movable barrier 44 may be far enough from the orifice 36 so that the effective cross sectional area of the orifice 36 is maximized, thereby increasing the flow rate of fuel from the cavity 34, through the orifice 36, and into the combustion chamber 24.

The movable barrier 44 may be connected to a hub 48 inside the cavity 34 and may include means for moving the movable barrier 44. For example, as shown in FIG. 2, each distal end 46 may be connected by a rod 50 or piston to the hub 48. Each rod 50 or piston may include internal or external threads 52 that provide a threaded engagement between each rod 50 and the hub 48. In this manner, the threaded engagement between each rod 50 and the hub 48 provides the means for moving the movable barrier 44. Alternately, or in addition, the means for moving the movable barrier 44 may comprise a pneumatic or hydraulic supply 54 connected to the hub 48. Air or another fluid may thus be supplied to the hub 48 to pneumatically or hydraulically extend or retract each rod 50 with respect to the hub 48. In still further embodiments, the means for moving the movable barrier 44 may comprise any articulated, threaded, ratcheted, hinged, or other mechanical structure known in the art for reciprocating movement.

The embodiment of the nozzle 30 shown and described with respect to FIG. 2 thus provides several advantages over existing designs. For example, a customer may determine a reactivity of the fuel and readily adjust the flow rate of fuel through the nozzle 30 by adjusting the position of the movable barrier 44. In this manner, the customer may adjust the effective cross sectional area of the orifices 36 in the nozzle 30 based on the reactivity of the fuel. As a result, the customer does not have to maintain an inventory of substitute nozzles and may instead switch between fuel types or different reactivity fuels without requiring an unscheduled or unwanted shutdown to replace the nozzle. In addition, the movable barrier 44 allows the customer to slightly adjust the position of the movable barrier 44 during steady-state operations to achieve a desired combustor output.

FIG. 3 shows is a simplified cross-section of a nozzle 60 according to an alternate embodiment of the present invention. As shown, the nozzle 60 generally includes a nozzle body 62 that defines a cavity 64 inside the nozzle 60 and one or more orifices 66 in the nozzle body 62 that provide fluid communication from the cavity 64 through the nozzle body 62. The nozzle 60 may further include a shroud 68 surrounding the nozzle body 62 with one or more swirler vanes 70 radially arranged between the shroud 68 and the nozzle body 62. A supply of fuel 72 connected to the nozzle 60 supplies fuel to the cavity 64. The fuel than flows through the one or more orifices 66, and the swirler vanes 70, if present, swirl the fuel entering the combustion chamber 24 prior to combustion.

As shown in FIG. 3, the nozzle 60 may further include one or more removable inserts 74 in one or more orifices 66. The removable inserts 74 may have various internal diameters corresponding to various reactivity levels in the fuel. In particular embodiments, the removable inserts 74 may comprise a solid insert that serves as a plug to completely block fuel flow through an individual orifice 66. In this manner, the removable inserts 74 may be installed in each orifice 66 or a subset of orifices 66 to reduce the effective cross sectional area of the orifices 66, thereby reducing the flow rate of fuel from the cavity 64, through the orifices 66, and into the combustion chamber 24. When desired, the removable inserts 74 may be removed from the orifices 66 so that the effective cross sectional area of the orifices 66 is maximized, thereby increasing the flow rate of fuel from the cavity 64, through the orifices 66, and into the combustion chamber 24.

FIGS. 4, 5, and 6 provide perspective views of removable inserts according to alternate embodiments of the present invention. For example, the removable insert 74 shown in FIG. 4 includes a smooth inner surface 76 and a threaded outer surface 78 that allows the removable insert 74 may be threaded into or out of the orifice 66. The removable insert 80 shown in FIG. 5 includes a smooth outer surface 82 and a grooved or rifled inner surface 84. The removable insert 86 shown in FIG. 6 similarly includes a smooth outer surface 82 with turbulators 88 on the inner surface. In this manner, the removable inserts 80, 86 shown in FIG. 5 or 6 may be press fit into the orifice 66, and the grooved inner surface 84 or turbulators 88 on the inner surface enhances swirling, acceleration, and/or mixing of fuel flowing through the removable inserts 80, 86.

The embodiment of the nozzle 60 shown and described with respect to FIGS. 3, 4, 5, and 6 thus provides several advantages over existing designs. For example, a customer may determine a reactivity of the fuel and readily adjust the flow rate of fuel through the nozzle 60 by installing or removing one or more removable inserts 74 from one or more orifices 66. In this manner, the customer may adjust the effective cross sectional area of the orifices 66 in the nozzle 60 based on the reactivity of the fuel. As a result, the customer does not have to maintain an inventory of substitute nozzles and may instead switch between fuel types or fuels having different reactivity levels without replacing the nozzle.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other and examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

Claims

1. A combustor nozzle comprising:

a. a nozzle body, wherein the nozzle body defines a cavity;

b. an orifice in the nozzle body, wherein the orifice provides fluid communication from the cavity through the nozzle body; and

c. a movable barrier proximate to the orifice, wherein the movable barrier has a first position in which the movable barrier at least partially obstructs the orifice.

2. The combustor nozzle as in claim 1, further comprising means for moving the movable barrier.

3. The combustor nozzle as in claim 1, wherein the movable barrier is inside the cavity.

4. The combustor nozzle as in claim 1, wherein the movable barrier reduces an effective cross sectional area of the orifice in the first position.

5. The combustor nozzle as in claim 1, wherein the movable barrier has a second position in which the movable barrier increases an effective cross sectional area of the orifice.

6. The combustor nozzle as in claim 1, further comprising a plurality of orifices in the nozzle body and a plurality of movable barriers proximate to the plurality of orifices, wherein the plurality of movable barriers have a first position that at least partially obstructs the plurality of orifices.

7. The combustor nozzle as in claim 1, further comprising a hub inside the cavity, wherein the barrier is connected to the hub.

8. The combustor nozzle as in claim 7, wherein the movable barrier is in threaded engagement with the hub.

9. A combustor nozzle comprising:

a. a nozzle body, wherein the nozzle body defines a cavity;

b. an orifice in the nozzle body, wherein the orifice provides fluid communication from the cavity through the nozzle body; and

c. a removable insert in the orifice, wherein the removable insert reduces effective cross sectional area of the orifice.

10. The combustor nozzle as in claim 9, wherein the removable insert as in threaded engagement with the orifice.

11. The combustor nozzle as in claim 9, wherein the removable insert is press fit into the orifice.

12. The combustor nozzle as in claim 9, wherein the removable insert has a grooved internal surface.

13. The combustor nozzle as in claim 9, wherein the removable insert has an internal surface and further comprising turbulators on the internal surface.

14. The combustor nozzle as in claim 9, further comprising a plurality of orifices in the nozzle body, wherein each of the plurality of orifices provides fluid communication from the cavity through the nozzle body.

15. The combustor nozzle as in claim 14, further comprising the removable insert in each of the plurality of orifices, wherein each removable insert reduces an effective cross sectional area of the orifice therein.

16. A method for supplying fuel to a combustor comprising:

a. flowing fuel through an orifice in a nozzle;

b. determining a reactivity of the fuel;

c. adjusting an effective cross sectional area of the orifice based on the reactivity of the fuel.

17. The method as in claim 16, further comprising reducing the effective cross sectional area of the orifice.

18. The method as in claim 16, further comprising installing an insert into the orifice.

19. The method as in claim 16, further comprising removing an insert from the orifice.

20. The method as in claim 16, further comprising flowing fuel through a plurality of orifices in the nozzle and adjusting an effective cross sectional area of the plurality of orifices based on the reactivity of the fuel.