Patent Application
20130269350
The subject matter disclosed herein relates to turbine combustors, and, more particularly, to a system for creating aerodynamic flow within a turbine combustor head end chamber.
A gas turbine engine combusts a fuel-air mixture in a combustion chamber of a turbine combustor, and then drives one or more turbines with the resulting hot combustion gases. In certain configurations, fuel and air are pre-mixed prior to ignition to reduce emissions and improve combustion. The gas turbine engine mixes the fuel and the air within one or more chambers, such as fuel nozzles. The fuel and air may travel together and/or separately through one or more paths through the turbine combustor. Unfortunately, the one or more paths may include sharp turns, recesses, and other obstructions that create recirculation zones, which may allow the flame holding and/or flashback.
Certain embodiments commensurate in scope with the originally claimed invention are summarized below. These embodiments are not intended to limit the scope of the claimed invention, but rather these embodiments are intended only to provide a brief summary of possible forms of the invention. Indeed, the invention may encompass a variety of forms that may be similar to or different from the embodiments set forth below.
In a first embodiment, a system includes a turbine combustor having a fuel nozzle with an inner shell and an outer shell and an feed cap disposed about the fuel nozzle having an outer wall and a back plate. The back plate joins respective upstream ends of the outer shell of the fuel nozzle and the outer wall of the feed cap. The turbine combustor is configured to flow a first pressurized air via a first air path extending along the outer wall of the feed cap, the back plate of the feed cap, and into the fuel nozzle.
In a second embodiment, a system includes a turbine combustor having: a combustion chamber, a head end chamber separated from the combustion chamber by a divider plate, and a pressurized chamber disposed in the head end chamber and about a fuel nozzle. The pressurized chamber includes a back plate that is joined to an upstream end of an outer shell of the fuel nozzle.
In a third embodiment, a system includes a turbine combustor having a combustion chamber, a head end chamber separated from the combustion chamber by a divider plate, and an air path disposed in the head end chamber and configured to flow a first pressurized air into a fuel nozzle. The air path includes a first segment disposed between a flow sleeve of the turbine combustor and an outer wall of an feed cap, and a second segment disposed downstream of the first segment and between a back plate of the feed cap and an end plate of the head end chamber. The second segment is substantially free of any flow-impeding surfaces between the back plate and the end plate. The air path also includes a third segment disposed downstream of the second segment and between inner and outer shells of the fuel nozzle.
These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
One or more specific embodiments of the present invention will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.
When introducing elements of various embodiments of the present invention, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.
As noted above, a head end of a gas turbine combustor, which is upstream from a combustion chamber, include areas that are generally not aerodynamic, such as areas that create turbulent flow via one or more sharp turns or edges, areas having low flow conditions where pockets of compressed air and fuel can accumulate, and areas where mixing of fuel and air is undesirable. In other words, the head end of the gas turbine combustor may include recirculation zones, which may include zones in which a mixture of fuel and air has low flow or research relates such that a flame can hold or flash back. Any one or a combination of these conditions can lead to undesirable combustion (e.g., flame holding or flashback) upstream from the combustion chamber of the gas turbine combustor, such as within a head end region or a feed cap region of the gas turbine combustor. The present embodiments include an aerodynamic feed cap design and the head end of the gas turbine combustor to reduce or eliminate recirculation zones. The feed cap may be a one-piece design configured to reduce the possibility forming low-flow regions, no-flow regions, areas of undesired turbulence, recirculation, mixing of fuel and air, and the like. Accordingly, the present embodiments may provide enhanced reliability of gas turbine engines, which in turn may result in more reliable energy production and increased throughput in integrated gasification systems, such as integrated gasification combined cycle (IGCC) systems. Indeed, the present embodiments may be used in any context employing a turbine combustor having areas where low-flow, no-flow, turbulence, and/or recirculation may create undesirable situations (e.g., flashback or flame holding).
Turning now to the drawings,
The turbine combustors 14 ignite and combust an air-fuel mixture, and then pass hot pressurized combustion gasses 24 (e.g., exhaust) into the turbine 16. Turbine blades are coupled to a shaft 26, which is also coupled to several other components throughout the turbine system 10. As the combustion gases 24 pass through the turbine blades in the turbine 16, the turbine 16 is driven into rotation, which causes the shaft 26 to rotate. Eventually, the combustion gases 24 exit the turbine system 10 via an exhaust outlet 28. Further, the shaft 26 may be coupled to a load 30, which is powered via rotation of the shaft 26. For example, the load 30 may be any suitable device that may generate power via the rotational output of the turbine system 10, such as an electrical generator, a propeller of an airplane, and so forth.
Compressor blades are included as components of the compressor 12. The blades within the compressor 12 are coupled to the shaft 26, and will rotate as the shaft 26 is driven to rotate by the turbine 16, as described above. The rotation of the blades within the compressor 12 compress air from an air intake 32 into pressurized air 34. The pressurized air 34 is then fed into the fuel nozzles 18 of the turbine combustors 14. The fuel nozzles 18 mix the pressurized air 34 and fuel to produce a suitable mixture ratio for combustion (e.g., a combustion that causes the fuel to more completely burn) so as not to waste fuel or cause excess emissions. As discussed below, the compressed air may pass through and/or around the feed cap in each combustor 14 upstream from fuel injection.
In certain embodiments, the head end 52 includes an end plate 66 that may support the primary fuel nozzles 20 depicted in
A fuel supply provides fuel 68 to the primary fuel nozzle 20. Additionally, an air flow path 72 delivers the pressurized air 34 from the annulus 60 of the turbine combustor 14 through the primary fuel nozzle 20. The primary fuel nozzle 20 combines the pressurized air 34 with the fuel 68 provided by the primary fuel supply 68 to form an fuel-air mixture. Specifically, the fuel 68 may be injected into the air flow path 72 by a plurality of swirl vanes 74 and, in some embodiments, additionally by one or more quaternary fuel injectors 97. The fuel-air mixture flows from the air flow path 72 into a combustion chamber 76 where the fuel-air mixture is ignited and combusted to form combustion gases (e.g., exhaust). The combustion gases flow in a direction 78 toward a transition piece 80 of the turbine combustor 14. The combustion gases pass through the transition piece 80, as indicated by arrow 82, toward the turbine 16, where the combustion gases drive the rotation of the blades within the turbine 16.
As noted above, the turbine combustor 14 includes regions where combustion is desired, such as the combustion chamber 76, and regions where combustion is undesirable, such as a head end chamber 84 disposed between the end plate 66 and a divider plate 86 separating the head end 52 from the combustion chamber 76. Combustion (e.g., flashback and/or flame holding) within the head end chamber 84 may be a result of turbulent air flow and fuel-air pockets along the air flow path 72, where the flow recirculates and/or has a low or no velocity in an upstream region, such as upstream of a combustion chamber and/or upstream of a fuel injector (e.g., fuel injector 20), and downstream of quaternary fuel injectors 97. Thus, in accordance with the present disclosure, it is now recognized that these and other undesirable flow conditions may be mitigated, at least in part, by providing an aerodynamic back plate 88 connecting an outer wall 90 of the feed cap 50 with an outer shell 92 of the fuel nozzle 20. Specifically, as discussed in detail below, the back plate 88 connects the outer shell 92 of the fuel nozzle 20 with the outer wall 90 of the feed cap 50 in such a way that the pressurized air 34 is able to flow along the air flow path 72 without encountering substantial turbulence or pockets of low flow or no flow. Further, the configuration of the back plate 88 may also help reduce the occurrence of pressure waves, acoustic waves, and other oscillations referred to as combustion dynamics, produced by the combustion process. Combustion dynamics may cause performance degradation, structural stresses, and mechanical or thermal fatigue in the turbine combustor 14 (e.g., within the head end chamber 84).
The back plate 88, the outer wall 90 of the feed cap 50, the outer shell 92 of the fuel nozzle 20, and the divider plate 86 together define a closed volume or chamber 94. The chamber 94, as illustrated, receives an influx of preconditioned air 96 from the set of quaternary fuel injectors 97 at a pressure that may be equal to or greater than a pressure of the pressurized air 34 flowing along the air path 72. Therefore, relative to the air path 72 and head end chamber 84, the chamber 94 may be considered to be a pressurized chamber. The chamber 94, in some embodiments, receives the preconditioned air 96 at a pressure that is between approximately 1 and 20% higher than the pressure of the pressurized air 34 and/or the air/fuel mixture flowing along the air path 72, such as between approximately 1 and 15%, 1 and 10%, 2 and 8%, 2 and 6%, or 3 and 5% (e.g., approximately 3%, 4%, or 5%) higher. Therefore, the chamber 94 may be sealed to the head end chamber 84, which may prevent an influx of the fuel and/or the air/fuel mixture from entering the chamber 94. In preventing such an influx, the chamber 94 may reduce the likelihood of premature combustion of the air/fuel mixture within the head end chamber 84 as a result of no flow or low flow of the air/fuel mixture. As discussed in further detail below, the chamber 94 may also enable cooling of the divider plate 86 by passing preconditioned air 96 into the combustion chamber 76. The preconditioned air 96 may be the pressurized air 34, or may be from another air source. As discussed below, the quaternary fuel injectors 97 may also inject fuel 86 into the air path 72 to form a fuel-air mixture. Accordingly, the configuration of the back plate 88, and in particular its manner of connection with the outer wall 90 of the feed cap 50 and the outer shell 92 of the fuel nozzle 20, reduces the possibility of flame holding and recirculation of the fuel-air mixture.
Indeed, the configuration of the back plate 88, as discussed herein, facilitates flow of the pressurized air 34 and the fuel-air mixture along the air flow path 72. As mentioned above, the air flow path 72 receives the pressurized air 34 from the annulus 60 of the turbine combustor 14. Additionally, in certain embodiments, the quaternary fuel injectors 97 inject fuel 68 into the flow path 72 to form the fuel-air mixture, which may also flow along the air flow path 72. The air flow path 72 includes a first portion 120, a second portion 122, and a third portion 123. The first portion 120, the second portion 122, and the third portion 123 are operatively coupled. The first portion 120 of the air flow path 72 is defined by an outer wall 124, which may be a head end casing or the flow sleeve 64, and the outer wall 90 of the feed cap 50. The second portion 122 of the air flow path 72 is defined by the end plate 66 of the head end chamber 84 and the back plate 88 of the feed cap 50. The outer shell 92 and an inner shell 130 of the fuel nozzle 20 define the third portion 123. In other words, the flow of the pressurized air 34 and/or the fuel-air mixture flows along an outer surface of the pressurized chamber 94 including a first outer surface of the feed cap 50 disposed around the fuel nozzle 20, an outer surface of the back plate 88, and an outer surface of the outer shell 92 of the fuel nozzle 20. As illustrated, the back plate 88 is disposed at the juncture of the first and second portions 120, 122 and the juncture of the second and third portions 122, 123. In accordance with present embodiments, the shape and positioning of the back plate 88 may facilitate flow of the pressurized air 34 between each portion.
For example, the first edge 104 of the back plate 88, which couples the back plate 88 with the outer wall 90 of the feed cap 50, may be rounded so as to prevent turbulent, recirculating, and/or low-velocity flow as the pressurized air 34 and/or fuel-air mixture flows from the first portion 120 to the second portion 122. Likewise, the second edge 106 of the back plate 88, which couples the back plate 88 with the outer shell 92 of the fuel nozzle 20, may be rounded so as to prevent turbulent, recirculating, and/or low-velocity flow as the pressurized air and/or fuel-air mixture flows from the second portion 122 to the third portion 123. The main portion 102 of the back plate 88 prevents the air and/or fuel-air flow from stalling. In other words, the main portion 102 prevents pockets of pressurized air 34 and/or the air/fuel mixture from becoming trapped in the second portion 122 by enabling continuous flow of the pressurized air 34 and/or the fuel-air mixture. Additionally, the main portion 102 is shaped to prevent areas where a crosswise flow of air is formed in the second portion 122. Generally, the back plate 88 will not have any surfaces that create flow shearing, such as protrusions, obstructions, recesses, and so on. Indeed, the outer wall 90, the back plate 88, and the outer shell 92 are configured such that the air path 72 is substantially free of no flow or low flow regions in which a flow of the pressurized air and/or fuel-air mixture is impeded, halted, or otherwise sheared. That is, the back plate 88 may be a substantially smooth, continuous surface.
As indicated by arrows 132, the pressurized air 34 flows from the annulus 60, first through the first portion 120 of the air flow path 72, through the second portion 122 of the air flow path 72, and then through the third portion 123. As noted, the pressurized air 34 may mix with the fuel 68, forming a fuel-air mixture. Therefore, in the first, second, and third portions 120, 122, 123, the arrows 132 may also represent the fuel-air mixture. The pressurized air 34 and/or fuel-air mixture also flows around the swirl vanes 74. As discussed above, the fuel 68 is released into the pressurized air 34 through the swirl vanes 74. Specifically, the fuel 68 flows down a fuel path 134 within the inner shell 130 of the fuel nozzle 20, as represented by arrows 136. The fuel 68 passes into the swirl vanes 74 from the fuel path 134, as represented by arrows 138, and exits the swirl vanes 74 through fuel ports 140 in the swirl vanes 74, as represented by arrows 142. The fuel 68 mixes with the pressurized air 34 to create an air/fuel mixture. The air/fuel mixture flows downstream, as indicated by arrows 144, toward the combustion chamber 76. In the illustrated embodiment, the divider plate 86 includes one or more openings 146 that operatively join the head end chamber 84 and the combustion chamber 76.
As mentioned above, the head end 52 of the turbine combustor 14 includes the chamber 94, which receives preconditioned air 96. Specifically, the preconditioned air 96 enters the chamber 94 through a preconditioned air inlet 148, while a flow of the fuel 86 enters the first portion 120 of the air flow path 72 through a series of fuel inlets 149. For example, the preconditioned air 96 may be supplied by the compressor discharge 54. While the illustrated embodiment shows two preconditioned air inlets 148, other embodiments may include fewer or more preconditioned air inlets 148. For example, the turbine combustor 14 may have 1, 3, 4, 5, 6, 7, 8, or more preconditioned air inlets 148. The chamber 94 receives preconditioned air 96 from the preconditioned air inlet 148 and fills with the preconditioned air 96, as indicated by arrows 150. Additionally, the preconditioned air 96 may be directed toward apertures 152 in the divider plate 86, as indicated by arrows 154. In certain embodiments, the apertures 152 may be straight or angled holes. The preconditioned air 96 may pass through the apertures 152, thereby cooling the divider plate 86 and entering the combustion chamber 76. As noted, the preconditioned air 96 is provided to the chamber 94 at a pressure sufficient to prevent the influx of the fuel-air mixture produced at the fuel nozzle 20 into the chamber 94. That is, the fuel-air mixture may be at a first pressure, the preconditioned air 96 within the chamber 94 may be at a second pressure, and the second pressure may be greater than the first pressure. Again, the preconditioned air 96 may be between approximately 1 and 15%, 1 and 10%, 2 and 8%, 2 and 6%, or 3 and 5% (e.g., approximately 3%, 4%, or 5%) higher than the pressurized air 34 and/or the fuel-air mixture. Additionally, in certain embodiments, the pressure within the chamber 94 may be at a level sufficient to prevent the influx of the combustion products produced within the combustion chamber 76.
As discussed above with respect to
For example, it will be appreciated that the central fuel nozzle 164 is not disposed proximate the outer wall 90 of the feed cap 50. Rather, the first and second outer fuel nozzles 160, 162 are positioned between the first and second central fuel nozzles 164, 166 and the outer wall 90. Thus, the preconditioned air 96 is not directly injected into the volume 168. Instead, the preconditioned air 96 is first directly injected into the chamber 94, and flows toward the central region of the head end 52, which includes the central fuel nozzle 164 and the volume 168. The preconditioned air 96 then fills the volume 168. Thus, the volume 168 and the chamber 94 are in direct flow communication, and may have the same pressure. Indeed, the volume 168 may have a pressure of preconditioned air 96 that is greater than a pressure of an air fuel mixture flowing through the central nozzle 164. For example, the pressure of the preconditioned air 96 within the volume 168 may be between approximately 1 and 15%, 1 and 10%, 2 and 8%, 2 and 6%, or 3 and 5% (e.g., approximately 3%, 4%, or 5%) higher than the pressurized air 34 and/or the fuel-air mixture.
As noted above, the back plate 88 may take on any aerodynamic form that connects the outer wall 90 of the feed cap 50 with the outer shell 92 of the fuel nozzle 20. That is, the back plate 88 is configured to maintain sufficient flow along all boundary surfaces so as to prevent recirculation of the fuel-air mixture and/or the pressurized air 34. Examples of such configurations are illustrated in
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 examples are intended to be within the scope of the claims if they have 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 language of the claims.
