Patent Application
20100024425
This present application relates generally to fuel nozzle assemblies that are used in combustors of gas turbines engines. More specifically, but not by way of limitation, the present application relates to a combined flange/outer tube assembly that may be used in gas turbine fuel nozzles.
Generally, a fuel nozzle assembly is utilized to deliver a mixture of fuel and air to the combustion chamber. One component of the fuel nozzle assembly is a flange, which connects the fuel nozzle assembly to an end cover. The flange secures the fuel nozzle directly to the end cover. The flange also connects to an outer tube that attaches to a fuel/air swirler or swozzle at its other end. As one of ordinary skill in the art will appreciate, the fuel nozzle generally behaves as a cantilevered beam, with the flange and the outer tube supporting the entire fuel nozzle structure that extends away from the end cover into the combustor. In use, the flange and outer tube generally provide structural support for the fuel nozzle and fuel passages through a concentric tube arrangement.
However, in conventional fuel nozzles, flange and outer tube design fails to provide durable support for the fuel nozzle. Further, among other shortcomings, conventional design fails to provide surface profiles that minimize aerodynamic interference and stress concentrations. Thus, there is a need for enhanced fuel nozzle design, particularly the design of the flange and outer tube, that addresses the issues of conventional apparatus.
The present application thus describes a fuel nozzle for a gas turbine combustor that includes an extended flange. At a first end, the extended flange may be configured to engage an end cover, thereby securing the position of the fuel nozzle within the combustor. At a second end, the extended flange may be configured to engage a swozzle, within which a supply of fuel and compressed air is mixed during the operation of the combustor. The extended flange may be formed as a single piece.
The present application also describes a fuel nozzle for a gas turbine combustor that includes an extended flange. At a first end, the extended flange may be configured to engage an end cover, thereby securing the position of the fuel nozzle within the combustor. At a second end, the extended flange may be configured to engage a swozzle, within which a supply of fuel and compressed air is mixed during the operation of the combustor. The extended flange may be formed as a single piece. The extended flange also may include a flange section, a middle section, and a tube section. The flange section may have a cylindrical shape. The middle section may include a curved surface that transitions from a surface of the flange section to a surface of the tube section. The tube section comprises a cylindrical shape that extends away from the middle section. Finally, the curved surface that transitions from the surface of the flange section to the surface of the tube section may have an approximate smooth elliptical surface.
These and other features of the present application will become apparent upon review of the following detailed description of the preferred embodiments when taken in conjunction with the drawings and the appended claims.
These and other objects and advantages of this invention will be more completely understood and appreciated by careful study of the following more detailed description of exemplary embodiments of the invention taken in conjunction with the accompanying drawings, in which:
Referring now to the figures, where the various numbers represent like parts throughout the several views,
In use, a supply of compressed air from the axial compressor may enter the combustion system 100 through small perforations or holes in the transition piece impingement sleeve 120. The compressed air may them move between the channel formed between the transition piece impingement sleeve 120 and the transition piece assembly 118, in the direction of the headend 104. The supply of compressed air may continue in that direction through the channel formed between the liner 116 and the flow sleeve 114. From there, the compressed air may flow into the volume bound by the forward case 110 and enter the fuel nozzles 108 through the inlet flow conditioner 142. At the fuel nozzles 108, generally, the supply of compressed air may be mixed with a supply of fuel, which is provided by a fuel manifold that connects to the fuel nozzles 108 through the end cover 106. The supply of compressed air and fuel is combusted as it exits the fuel nozzles 108, which creates a flow of rapidly moving hot gases that is directed downstream through the cavities within the liner 116 and the transition piece assembly 108 toward the turbine section, where the energy of the flow may be converted into the mechanical energy of rotating turbine blade airfoils.
An exterior tube may enclose approximately 75% of the fuel nozzle 130. At the section of the exterior tube that overlaps the outer tube 136, small holes or perforations may form an inlet flow conditioner 142. Inside the inlet flow conditioner 142, is an inlet flow conditioner baffle 144. Extending away from the swozzle 138 is a diffuser tip 146. The section of the exterior tube that covers the diffusion tip 146 may form a burner tube 140. The inner tube 148 may be formed inside the outer tube 136, creating a concentric circle channel between the inner tube 148 and the outer tube 136 and another channel inside the hollow inner tube 148. These channels may be used to supply fuels to the fuel nozzle 108.
The conventional fuel nozzle 130 may operate as follows. Compressed air, which may be supplied an axial compressor, may flow into the forward case 110 of the combustion system 100 and may enter the fuel nozzle 130 through the perforations of the inlet flow conditioner 142. It will be appreciated that the flow of compressed air in the forward case 10 generally must change direction to enter the inlet flow conditioner 142, that some of the compressed air will be deflected off of the flange 132 toward the inlet flow conditioner 142, and that flow in this area generally will be turbulent. A fuel, such as natural gas, may enter the nozzle 130 through a channel through the flange 132. The fuel may flow toward the swozzle 138 in the channel formed between the outer tube 136 and the inner tube 148. Note that liquid fuels and purge air may be supplied through the channel formed inside the inner tube 148. The fuel and the compressed air may mix in the swozzle 138 and exit through the far end of the burner tube 140 where it is combusted.
Those of ordinary skill in the art will appreciate that fuel nozzles generally are highly stressed parts. The operational stresses include vibratory loads, thermal loads, aerodynamic loads, and others. As one of ordinary skill in the art will appreciate, fuel nozzles 108 are cantilevered parts, i.e., fuel nozzles 108 are structurally supported by the connection they make to the end cover 106 through the outer tube 136/flange 132 assembly. As a result, high stress concentrations occur through the outer tube 136 and flange 132 parts.
The middle section 156 generally is the section that makes the transition from the flange section 154 to the tube section 158. As illustrated, the middle section 156 is an approximate flared cylinder. The flared cylinder of the middle section 156 generally has a larger diameter where the middle section 156 connects to the flange section 154 and a smaller diameter where the middle section 156 connects to the tube section 158. It will be appreciated that the flange section 154 is generally a piece that extends in the radial direction (or, as illustrated, the vertical direction), while the tube section 158 is a section that generally extends in the axial direction (or, as illustrated, the horizontal direction), away from the flange section 154. That is, the middle section 156 transitions from a radially oriented surface (or, as illustrated, a vertical surface) of the flange section 154 to an axially oriented surface (or, as illustrated, a horizontal surface) of the tube section 158 with an approximate smooth elliptical surface. In some embodiments, the middle section 156 transitions from the radially oriented surface of the flange section 154 to the axially oriented surface of the tube section 158 with an approximate smooth multi-radial curve. The axial thickness of the middle section 156 is generally between 0.5 and 1.0 inches.
Finally, the tube section 158 is a section of tube that extends in the axial direction (or, as illustrated, the horizontal direction) away from the middle section 156. In some embodiments, the tube section 150 is an approximate cylinder shape, though other shapes are possible. The axial thickness of the tube section 158 is generally between 3.0 and 9.0 inches. Note that, though the extended flange 152 has been described in terms of three sections, the extended flange 152 may be constructed as an integral part. The axial thickness of the extended flange 152 is generally between 3.75 and 10.75 inches. In some environments, the axial thickness of the extended flange 152 is the distance required such that, when one end of the extended flange 152 is connected to the end cover 106 and the other end is connected to the swozzle 138, the fuel nozzle is appropriately positioned in the combustor.
As illustrated in
As illustrated, passages may be formed through the flange section 154 and the portion of the middle section 156 in which the central chamber 162 is not formed. These passages generally pass through the flange section 154 and a portion of the middle section 156 to connect with the central chamber 162. A center passage 170 may be formed in the approximate center of the flange section 154 and generally pass through a portion of the middle section 156 to connect with the central chamber 162. An outer passage 172 may be formed around the periphery of the center passage. The outer passage 172 may also pass through a portion of the middle section 156 to connect with the central chamber 162.
As illustrated in
In addition, the connection between the outer tube 136 and the flange 132 is eliminated with the extended flange 152. As described, the extended flange 152 may be an integral part, i.e., formed as a single piece. The elimination of this connection saves costs associated with assembling the fuel nozzle. Further, it also provides greater durability to the fuel nozzle. The brazed connection made between a conventional outer tube 136 and flange 132 generally has a shorter operational part life than a similar part that is formed as a single piece. The brazed connection also occasionally fails during operation requiring significant repairs to the combustor unit.
From the above description of preferred embodiments of the invention, those skilled in the art will perceive improvements, changes and modifications. Such improvements, changes and modifications within the skill of the art are intended to be covered by the appended claims. Further, it should be apparent that the foregoing relates only to the described embodiments of the present application and that numerous changes and modifications may be made herein without departing from the spirit and scope of the application as defined by the following claims and the equivalents thereof.
