Patent Publication Number: US-8122721-B2

Title: Combustion turbine engine and methods of assembly

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to rotary machines and more particularly, to methods and apparatus for assembling combustion turbine engines. 
     Many known combustion turbine engines ignite a fuel-air mixture in a combustor and generate a combustion gas stream that is channeled to a turbine via a hot gas path. Compressed air is channeled to the combustor by a compressor. Combustor assemblies typically have fuel nozzles that facilitate fuel and air delivery to a combustion region of the combustor. The turbine converts the thermal energy of the combustion gas stream to mechanical energy that rotates a turbine shaft. The output of the turbine may be used to power a machine, for example, an electric generator or a pump. 
     Many known fuel nozzle assemblies have a variety of components manufactured from a variety of materials that are joined together with brazed joints. These materials, including the brazed joints, may have differing thermal growth properties which have differing rates and magnitudes of thermal expansion and contraction. 
     Fuel nozzle assemblies are normally within near proximity of the combustion region of the combustor assemblies. Due to the near proximity to the combustion regions, the nozzles and their constituent components may experience temperature variations ranging from substantially room temperature of approximately 24° Celsius (C.) (75° Fahrenheit (F.)) to operating temperatures of approximately 1316° C. to 1593° C. (2400° F. to 2900° F.). Therefore, the large range of temperature variations in conjunction with the differing thermal expansion and contraction properties of the fuel nozzle assemblies materials causes stresses in the brazed joints, including the brazed joints associated with combustor end covers and fuel nozzle inserts. 
     BRIEF DESCRIPTION OF THE INVENTION 
     In one aspect, a method of assembling a combustion turbine engine in provided. The method includes coupling at least one fuel nozzle inner atomized air tube to a combustor end cover plate body, and assembling a fuel nozzle insert sub-assembly by inserting at least one flow control apparatus into a fuel nozzle insert sub-assembly body. The method further includes inserting at least one seal between the combustor end cover plate body and the fuel nozzle insert sub-assembly body, and within at least a portion of an annular diffusion fuel passage, and inserting at least one seal between the combustor end cover plate body and the fuel nozzle insert sub-assembly body, and within at least a portion of a pre-orifice premix fuel annulus. The method also includes coupling the fuel nozzle insert sub-assembly body to the combustor end cover plate body, inserting at least one bellows onto a bellows support fitting, inserting the bellows support fitting onto a fuel nozzle insert sub-assembly body support surface, and assembling a fuel nozzle sub-assembly by coupling at least one radially outer tube, at least one radially inner tube, at least one intermediate tube, and at least one fuel nozzle mounting flange. The method further includes assembling a fuel nozzle assembly by coupling the fuel nozzle sub-assembly to the combustor end cover plate body. 
     In another aspect, a fuel nozzle assembly is provided. The fuel nozzle assembly includes a combustor end cover sub-assembly, at least one fuel nozzle insert sub-assembly and a fuel nozzle sub-assembly. The cover sub-assembly includes a combustor end cover plate body. The insert sub-assembly includes an insert body and at least one flow control apparatus. The fuel nozzle sub-assembly includes at lest one tube. The fuel nozzle assembly also includes a plurality of seals. The seals are inserted between the insert body, the end cover plate body and the tube wall. 
     In a further aspect, a combustion turbine engine is provided. The engine includes a compressor. The engine also includes at least one fuel source, and a combustor in flow communication with the compressor. The combustor includes a fuel nozzle assembly and the fuel nozzle assembly includes a combustor end cover sub-assembly, at least one fuel nozzle insert sub-assembly, and a plurality of seals. The cover assembly includes a combustor end cover plate body. The insert sub-assembly includes an insert body and at least one flow control apparatus. The flow control apparatus is configured to facilitate a substantially repeatable predetermined distribution of fuel within the engine. The seals are inserted between the insert body, the end cover plate body and the tube wall. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic illustration of an exemplary combustion turbine engine; 
         FIG. 2  is a fragmentary illustration of an exemplary fuel nozzle assembly that may be used with the combustion turbine engine in  FIG. 1 ; 
         FIG. 3  is an expanded fragmentary illustration of an exemplary fuel nozzle assembly that may be used with the combustion turbine engine in  FIG. 1 ; and 
         FIG. 4  is a fragmentary illustration of an alternate embodiment of a bellows arrangement that may be used with the combustion turbine engine in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is a schematic illustration of an exemplary combustion turbine engine  100 . Engine  100  includes a compressor  102  and a combustor  104 . Combustor  104  includes a combustion region  105  and a fuel nozzle assembly  106 . Engine  100  also includes a turbine  108  and a common compressor/turbine shaft  110  (sometimes referred to as rotor  110 ). In one embodiment, engine  100  is a MS7001FB engine, sometimes referred to as a 7FB engine, commercially available from General Electric Company, Greenville, S.C. The present invention is not limited to any one particular engine and may be implanted in connection with other engines including, for example, the MS7001FA (7FA), MS9001FA (9FA), and MS9001FB (9FB) engine models of General Electric Company. 
     In operation, air flows through compressor  102  and compressed air is supplied to combustor  104 . Specifically, a substantial amount of the compressed air is supplied to fuel nozzle assembly  106  that is integral to combustor  104 . Some combustors have at least a portion of air flow from compressor  104  distributed to a dilution air sub-system (not shown in  FIG. 1 ) and most combustors have at least some seal leakage. Assembly  106  is in flow communication with combustion region  105 . Fuel nozzle assembly  106  is also in flow communication with a fuel source (not shown in  FIG. 1 ) and channels fuel and air to combustion region  105 . Combustor  104  ignites and combusts fuel, for example, natural gas and/or fuel oil, that generates a high temperature combustion gas stream of approximately 1316° Celsius (C.) to 1593° C. (2400° Fahrenheit (F.) to 2900° F.). Combustor  104  is in flow communication with turbine  108  gas stream thermal energy is converted to mechanical rotational energy. Turbine  108  is rotatably coupled to and drives rotor  110 . Compressor  102  also is rotatably coupled to shaft  110 . In the exemplary embodiment, there is a plurality of combustors  104  and fuel nozzle assemblies  106 . In the following discussion, unless otherwise indicated, only one of each component will be discussed. 
       FIG. 2  is a fragmentary illustration of an exemplary fuel nozzle assembly  200  that may be used with combustion turbine engine  100  (shown in  FIG. 1 ) as a component of combustor  104  (shown in  FIG. 1 ). Assembly  200  includes at least one fuel supply feed  202 , and an atomized air cartridge sub-assembly  203 . Sub-assembly  203  includes a plurality of air supply tubes  204  coupled to a plurality of inner atomized air tubes  205 . Assembly  200  also includes a combustor end cover sub-assembly  206 . Cover sub-assembly  206  includes a plurality of open passages for channeling air and fuel (discussed further below), an end cover plate body  208 , and a plurality of end cover-to-combustor casing fasteners  210 . In the exemplary embodiment, body  208  is formed using a machining process that includes forming a plurality of cavities within body  208  to subsequently receive, but not be limited to, a plurality of premix fuel supply passages  218 , a diffusion fuel supply passage  220 , a plurality of atomized air supply tubes  204 , a fuel nozzle insert sub-assembly  212  (discussed further below), a plurality of end cover-to-combustor casing fasteners  210 , a plurality of insert-to-end cover fasteners  214 , and a plurality of cap-to-end cover fasteners  217 . Alternatively, an existing model of body  208  may be retrofitted to substantially resemble body  208  of the exemplary embodiment. Cover sub-assembly  206  is coupled to combustor  104  (shown in  FIG. 1 ) casings via fasteners  210 . Atomizing air cartridge sub-assemblies  203  are coupled to end cover plate body  208 . 
     Assembly  200  also includes a plurality of fuel nozzle insert sub-assemblies  212  (discussed in more detail below) and a fuel nozzle sub-assembly  225 . The fuel nozzle sub-assembly includes a plurality of nozzle radially outer tubes  216 , a plurality of intermediate tubes  223 , a cap mounting flange  222 , a plurality of radially inner tubes  221 , an annular diffusion fuel passage  219  and a fuel nozzle cap  224 . Fuel nozzle insert sub-assembly  212  is coupled to end cover plate body  208  via fasteners  214 . Cap  224  is coupled to end cover plate body  208  via fasteners  217  and cap mounting flange  222 . 
     Fuel is channeled to assembly  200  via at least one supply feed  202  from a fuel source (not shown in  FIG. 2 ). Premix fuel is channeled to tube  216  via passage  218  and fuel nozzle insert sub-assembly  212  as illustrated by the associated arrows. Diffusion fuel is channeled to passage  219  via tube  220  as illustrated by the associated arrows. Combustion air is channeled from compressor  102  (shown in  FIG. 1 ) to air supply tubes  204  from where it is further channeled to tube  205  as illustrated by the associated arrows. Generally, a plurality of fuel nozzle assemblies  200  (only one illustrated in  FIG. 2 ) are arranged circumferentially around shaft  110  (shown in  FIG. 1 ) such that a circumferential stream of combustion gas with a substantially uniform temperature is generated within combustor  104  and channeled to turbine  108  (shown in  FIG. 1 ). A portion of fuel nozzle assembly  200 , including insert sub-assembly  212 , as illustrated within the dotted lines, is enlarged in  FIG. 3  and discussed in more detail below. 
       FIG. 3  is an expanded fragmentary illustration of an exemplary fuel nozzle assembly  300  that may be used with combustion turbine engine  100  (shown in  FIG. 1 ). Assembly  300  includes an end cover plate body  302  and a fuel nozzle insert sub-assembly  304 . Sub-assembly  304  includes a body  305  and a plurality of orifice plugs  306  (only two illustrated in  FIG. 3 ). In the exemplary embodiment, body  305  is formed using a machining process that includes forming a plurality of cavities and passages within body  305  to subsequently receive, but not be limited to, orifice plugs  306  and a plurality of insert-to-end cover fasteners  307  (only one illustrated in  FIG. 3 ). Fuel nozzle insert sub-assembly  304  is assembled via inserting plugs  306  into the associated cavities in body  305 . Each orifice plug  306  has at least one orifice opening  309 . 
     Assembly  300  further includes at least one premix fuel supply passage  308  and a diffusion fuel supply passage  310 . Passages  308  and  310  are formed in body  302  during a machining process. Assembly  300  further includes a pre-orifice premix fuel annulus  312 , an annular diffusion fuel passage  314 , an inner atomized air tube  316  that forms an inner atomized air passage  318 , a post-orifice premix fuel annulus  320 , and a fuel nozzle sub-assembly  321 . Fuel nozzle sub-assembly  321  includes a radially outer tube  322 , a radially inner tube  328 , a premix fuel supply passage  326 , and an intermediate tube  324 . Annulus  312  is formed during the assembly process as insert body  305  is coupled to body  302 . Passage  314  is also formed during the assembly process by tube  316 , body  302 , body  305 , and tube  328 . Annulus  320  is formed via body  305  and support fitting  333  (discussed further below). Passage  326  is formed by intermediate tube  324 , radially inner tube  328  and insert body  305 . Shroud  336  is dimensioned such that the clearance between shroud  336  and body  305  is large enough to facilitate thermal growth and small enough to facilitate mitigating air leakage. 
     Sub-assembly  300  further includes a first seal  330 , a second seal  332 , a third seal support fitting  333 , a bellows  334  and a bellows support fitting support surface  335 . 
     First seal  330  is an annular W-type seal (referred to as a W-type seal due to the shape that substantially resembles the letter W) that is positioned within the upstream region of passage  314  between end cover plate body  302  and insert sub-assembly  304 . Alternatively, seal  330  may be a C-type seal, an E-type seal, or any other seal type that meets or exceeds the predetermined characteristics of a seal used in the operation of assembly  300 . Seal  330  is positioned, dimensioned and shaped to facilitate a mitigation of fuel leakage between passage  314  and annulus  312 . Seal  330  is positioned between sub-assembly  304  and body  302  within a portion of annular diffusion fuel passage  314 . 
     Second seal  332  is also an annular W-type seal that is positioned within annulus  312  between end cover plate body  302  and insert sub-assembly  304 . Alternatively, seal  332  may be a C-type seal, an E-type seal, or any other seal type that meets or exceeds the predetermined characteristics of a seal used in the operation of assembly  300 . Seal  332  is positioned, dimensioned and shaped to facilitate a mitigation of fuel leakage between annulus  312  and area outside of shroud  336 . Second seal  332  is positioned between sub-assembly  304  and body  302  within pre-orifice premix fuel annulus  312  that is formed by body  302  and body  305 . 
     Bellows  334  is an annular metallic bellows that is positioned within passage  314  between insert sub-assembly  304  and radially inner tube  328 . Bellows  334  is positioned, dimensioned and shaped to facilitate a mitigation of fuel leakage between annulus  320  and passage  314  by accommodating thermal growth differentials between tubes  324  and  328 . Support fitting  333  includes an annular shape and is positioned over bellows  334 . In the exemplary embodiment, seal support  333  is positioned within annulus  320 . 
     Bellows  334  is inserted into fuel nozzle assembly  300 . Tube  328  is welded to bellows  334  and is positioned such that a portion of tube  328  is in contact with support fitting  333 . Bellows  334  is also welded to fitting support surface  335 . A portion of support fitting  333  is brazed to fitting support surface  335  on the annulus  320  side of bellows  334  and facilitates support for bellows  334  to mitigate a potential for buckling or other deformation of bellows  334  that may reduce its sealing effectiveness. Support fitting  333  and body  305  form post-orifice premix fuel annulus  320 . 
     Seals  330  and  332  and bellows  334  are compressed to a predetermined length during assembly (discussed further below) and expand and contract during increasing and decreasing temperature conditions, respectively, throughout the range of operation of engine  100  (shown in  FIG. 1 ). Seals  330  and  332  and bellows  334  may be manufactured of flexible materials that are substantially resistant to high-temperatures. Seals  330  and  332  are inserted into sub-assembly  304  such that they may be reused upon reassembly subsequent to disassembly for maintenance activities. 
     Insert sub-assembly  304  is coupled to end cover plate body  302  with first seal  330  and second seal  332  correctly positioned. Fasteners  307  (only one illustrated in  FIG. 3 ) are used to couple body  305  to body  302 . Fastening body  305  to body  302  compresses seals  330  and  332  to predetermined lengths and maintains seals  330  and  332  in position with a potential for inadvertent removal from the predetermined positions mitigated. 
     Plugs  306  contain orifices  309  that are positioned within insert body  305  and dimensioned to channel a predetermined rate of premix fuel flow to fuel nozzle sub-assembly  321  such that fuel is substantially evenly distributed across the plurality of nozzles (only one shown in  FIG. 3 ) and substantially complete and uniform fuel combustion at a predetermined temperature is facilitated. Premix fuel enters sub-assembly  300  via at least one supply passage  308  and is channeled to pre-orifice premix fuel annulus  312 . Annulus  312  extends circumferentially within combustor  104  around fuel nozzle sub-assembly  321  such that fuel pressure upstream of orifice plugs  306  is substantially similar throughout annulus  312  and facilitates substantially uniform fuel flow to each nozzle sub-assembly  321 . Premix fuel is channeled to post-orifice premix fuel annulus  320  that also extends circumferentially around nozzle sub-assembly  321  within combustor  104  such that substantially similar fuel pressure and fuel flow to each nozzle sub-assembly  321  is facilitated. Fuel flow is channeled to combustion region  105  (shown in  FIG. 1 ) via premix fuel supply passage  326 , passage  326  being formed with radially inner tube  328  and intermediate tube  324 . Premix fuel flow is illustrated with the associated arrows. Orifice plugs  306  are fixedly inserted to insert sub-assembly  304  such that a potential for an orifice-to-nozzle mismatch during reassembly activities subsequent to disassembly for maintenance activities is mitigated. 
     Diffusion fuel is channeled to combustion region  105  via diffusion supply passage  310  and annular diffusion passage  314 . Passage  314  is formed with insert body  305 , bellows  334 , radially inner tube  328  and inner atomized air tube  316 . Diffusion fuel flow is illustrated with the associated arrows. 
     Air is channeled to combustion region  105  via air tube  316  and air flow is illustrated with the associated arrows. 
     Assembly  300  also includes a shroud  336  with annular shroud air passages  337 , and a plurality of vanes  338  (typically 8 to 12) for mixing air from combustors  104  via passages  337  with fuel from post-orifice premix fuel annulus  320 . Vanes  338  include vane shroud  340 . The fuel and air mixture is subsequently transported to the fuel nozzle tip (not shown in  FIG. 3 ) by the passage formed by radially outer tube  322  and intermediate tube  324 . Vane shroud  340  is welded to shroud  336 . 
       FIG. 4  is a fragmentary illustration of an alternate embodiment of a bellows arrangement  400  that may be used with combustion turbine engine  100  (shown in  FIG. 1 ). Arrangement  400  includes end cover plate body  402 , pre-orifice premix fuel annulus  403 , fuel nozzle insert body  404 , seal  405 , orifice plug  406  with orifice  407 , post-orifice premix fuel annulus  408 , bellows  410 , bellows support fitting  412 , bellows support fitting support surface  413 , intermediate tube  416 , radially inner tube  414 , shroud  418  with annular shroud air passages  422 , annular diffusion fuel passage  420 , vanes  424  and vane shroud  426 . In this alternate embodiment, support fitting  412  is positioned on the passage  420  side of bellows  410  as compared to the annulus  408  side of bellows  410  to mitigate tube  414  vibration during operations. 
     Seal  405  is an annular W-type seal that is positioned within pre-orifice premix fuel annulus  403  formed between end cover plate body  402  and fuel nozzle insert body  404 . Alternatively, seal  405  may be a C-type seal, an E-type seal, or any other seal type that meets or exceeds the predetermined characteristics of a seal used in the operation of bellows arrangement  400 . 
     Bellows  410  is welded to fitting  412  on the tube  414  side. Bellows  410  is also welded to bellows support fitting support surface  413 . Support surface  413  is brazed to body  404 . Support fitting  412  is positioned to have a slip fit contact with support surface  413 . Support fitting  412  is welded to tube  414 . Shroud  418  is welded to vane shroud  426 . Tube  414  is brazed to tube  416 . Tube  416  is brazed to body  404  and shroud  418  is positioned to have a contact slip fit with body  404 . 
     Plug  406  contains orifice  407  that is positioned within insert body  404  and dimensioned to channel a predetermined rate of premix fuel flow to annulus  408  such that fuel is substantially evenly distributed across a plurality of nozzles (not shown in  FIG. 4 ) and substantially complete and uniform fuel combustion at a predetermined temperature is facilitated. Assembly  400  in  FIG. 4  illustrates air from combustor  104  being channeled through shroud passages  422  to enter vanes  424  and mix with premix fuel being channeled to vane  424  from annulus  408 . The fuel and air mixture is subsequently transported to the fuel nozzle tip (not shown in  FIG. 4 ). 
     The methods and apparatus for a fuel nozzle assembly described herein facilitate operation of a combustion turbine engine. More specifically, designing, assembling, installing and operating a fuel nozzle assembly as described above facilitates operation of a combustion turbine engine by mitigating fuel losses within a fuel nozzle. Also, insertion of reusable seals within the fuel nozzle assemblies may mitigate seal replacement activities. Furthermore, fixedly coupling orifice plugs to a fuel nozzle insert sub-assembly mitigates the potential for erroneously installing the orifice plugs in an alternate insert sub-assembly. As a result, facilitation of a uniform fuel-to-air ratio is enhanced and degradation of combustion turbine efficiency, the associated increase in fuel costs, extended maintenance costs and engine outages may be reduced or eliminated. 
     Although the methods and apparatus described and/or illustrated herein are described and/or illustrated with respect to methods and apparatus for a combustion turbine engine, and more specifically, a fuel nozzle assembly, practice of the methods described and/or illustrated herein is not limited to fuel nozzle assemblies nor to combustion turbine engines generally. Rather, the methods described and/or illustrated herein are applicable to designing, installing and operating any system. 
     Exemplary embodiments of fuel nozzle assemblies as associated with combustion turbine engines are described above in detail. The methods, apparatus and systems are not limited to the specific embodiments described herein nor to the specific fuel nozzle assembly designed, installed and operated, but rather, the methods of designing, installing and operating fuel nozzle assemblies may be utilized independently and separately from other methods, apparatus and systems described herein or to designing, installing and operating components not described herein. For example, other components can also be designed, installed and operated using the methods described herein. 
     While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.