Abstract:
A turbomachine includes a compressor, a turbine operatively coupled to the compressor, and a combustor fluidly linking the compressor and the turbine. The combustor includes at least one fuel nozzle. The at least one fuel nozzle includes a flow passage including a body having first end that extends to a second end through at least one flow channel having a flow area. A fuel inlet is provided at the first end of the body. The fuel inlet is configured to receive at least one fuel. A fuel outlet is provided at the second end of the body. A control flow passage is fluidly connected to the body between the first and second ends. The control flow passage is configured and disposed to deliver a control flow into the fuel nozzle. The control flow establishes a selectively variable effective flow area of the flow passage.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The subject matter disclosed herein relates to the art of turbomachines and, more particularly, to a fuel nozzle for a turbomachine. 
         [0002]    Turbomachines typically include a compressor, a combustor and a turbine. In operation, air flows through the compressor, is compressed and supplied to the combustor. Fuel is also channeled to the combustor, mixed with the compressed air, and ignited to form combustion gases. The combustion gases are channeled to the turbine. The turbine converts thermal energy from the combustion gases to mechanical, rotational energy that is used to power the compressor as well as to produce useful work such as to operate an electrical generator. Conventional turbomachines are designed to operate on a particular fuel or family of fuels. 
         [0003]    The regulatory requirements for low emissions from gas turbine power plants have grown more stringent over the years. Environmental agencies throughout the world are now requiring even lower rates of emissions of NOx and other pollutants from both new and existing gas turbines. Traditional methods of reducing NOx emissions from combustion turbines (water and steam injection) are limited in their ability to reach the extremely low levels required in many localities. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0004]    According to one aspect of the invention, a turbomachine includes a compressor, a turbine operatively coupled to the compressor, and a combustor fluidly linking the compressor and the turbine. The combustor includes at least one fuel nozzle. The at least one fuel nozzle includes a flow passage including a body having first end that extends to a second end through at least one flow channel having a flow area. A fuel inlet is provided at the first end of the body. The fuel inlet is configured to receive at least one fuel. A fuel outlet is provided at the second end of the body. At least one control flow passage is fluidly connected to the body between the first and second ends. The at least one control flow passage is configured and disposed to deliver at least one control flow into the fuel nozzle. The at least one control flow establishes a selectively variable effective flow area of the flow passage. 
         [0005]    According to another aspect of the invention, a turbomachine fuel nozzle includes a flow passage including a body having first end that extends to a second end through at least one flow channel having a flow area. A fuel inlet is provided at the first end of the body. The fuel inlet is configured to receive at least one fuel. A fuel outlet is provided at the second end of the body. At least one control flow passage is fluidly connected to the body between the first and second ends. The at least one control flow passage is configured and disposed to deliver at least one control flow into the fuel nozzle. The at least one control flow establishes a selectively variable effective flow area of the flow passage. 
         [0006]    According to yet another aspect of the invention, a method of selectively varying an effective flow area of a turbomachine fuel nozzle includes receiving at least one fuel into a fuel inlet of the fuel nozzle, guiding the at least one fuel along a flow passage including a flow channel having a flow area, introducing at least one control flow downstream of the fuel inlet, and varying an effective flow area of the flow passage with the at least one control flow. 
         [0007]    These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0008]    The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
           [0009]      FIG. 1  is a schematic diagram of a turbomachine including a combustor fuel nozzle in accordance with an exemplary embodiment; 
           [0010]      FIG. 2  is a cross-sectional schematic view of a combustor fuel nozzle in accordance with one aspect of the exemplary embodiment; and 
           [0011]      FIG. 3  is a cross-sectional schematic view of a combustor fuel nozzle in accordance with another aspect of the exemplary embodiment. 
       
    
    
       [0012]    The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0013]    With reference to  FIG. 1 , a turbomachine constructed in accordance with an exemplary embodiment is indicated generally at  2 . Turbomachine  2  includes a compressor  4  and a plurality of circumferentially spaced combustors, one of which is indicated at  6 . Combustor  6  includes a combustion chamber  8  that channels hot gases to a turbine  10  that is operatively coupled to compressor  4  through a common compressor/turbine shaft or rotor  12 . 
         [0014]    In operation, air flows through compressor  4  such that compressed air is supplied to combustor  6 . Fuel is channeled to combustion chamber  8 , mixed with air, and ignited to form combustion gases. The combustion gases are channeled to turbine  10  wherein gas stream thermal energy is converted to mechanical, rotational energy. Turbine  10  is rotatably coupled to, and drives, shaft  12 . It should be appreciated that the term “fluid” as used herein includes any medium or material that flows and is not limited to gas and/or air. In addition, the term fuel should be understood to include mixtures of fuels, diluents (N 2 , Steam, CO 2 , and the like, and/or mixtures of fuels and diluents. 
         [0015]    Fuel is passed to combustion chamber  8  through a plurality of combustor fuel nozzles, one of which is indicated at  20 . In accordance with an exemplary embodiment, combustor fuel nozzle  20  constitutes a dual fuel nozzle. More specifically, combustor fuel nozzle  20  injects a first fuel and/or a second fuel, where the two fuels may have widely disparate energy content, into combustion chamber  8 . In accordance with one aspect of the exemplary embodiment natural gas may be the first fuel and syngas may be the second fuel. Further, syngas fuel may be a 20%/36%/44% combination of natural gas/hydrogen/carbon monoxide (NG/H2/CO). 
         [0016]    As best shown in  FIG. 2 , combustor fuel nozzle  20  includes an outer nozzle portion  29  and an inner nozzle portion  31 . Outer nozzle portion  29  includes a body portion  36  having a first end portion  38  that extends to a second end portion  39 . Body portion  36  is further shown to include an outer wall  41  and an inner wall  42  that defines a plenum  44 . First end portion  38  defines an inlet portion  46  and second end portion  39  defines an outlet portion  47  having a plurality of openings  48 . As shown, inner nozzle portion  31  extends into outer nozzle portion  29 . More specifically, inner nozzle portion  31  extends through first end portion  38  into plenum  44  and is coupled to inner wall  42  in a manner that will be described more fully below. 
         [0017]    Inner nozzle portion  31  includes a body section  60  having a first end section  62  that extends to a second end section  63 . Body section  60  is also shown to include an outer wall  66  and an inner wall  67  that defines a plenum  69 . First end section  62  defines an inlet section  72 , and second end section  63  defines an outlet section  73  having a plurality of openings  74 . Inner nozzle portion  31  is connected to inner wall  42  of outer nozzle portion  29  through a circumferential flange  77  having first and second seal lands  79  and  80  provided with corresponding seals (not shown). In accordance with an exemplary embodiment, combustor fuel nozzle  20  further includes a duel fuel flow passage  84  that extends through inner nozzle portion  31 . As will become more fully evident below, combustor fuel nozzle  20  relies upon a Coand{hacek over (a)} effect to guide first and/or second fuels through dual fuel flow passage  84 . 
         [0018]    In accordance with an exemplary embodiment, dual fuel flow passage  84  includes a body  88  having a first end  91  that extends to a second end  92 . First end  91  defines a fuel inlet  95 , while second end  92  defines a fuel outlet  96  that extends though outlet section  73 . Dual fuel flow passage  84  includes a first flow channel  101  that extends from fuel inlet  95 , a second flow channel  102  that is fluidly coupled to first flow channel  101 , a third flow channel  103  that is also fluidly coupled to first flow channel  101 , and a fourth flow channel  104  that fluidly links second and third flow channels  102  and  103  with fuel outlet  96 . 
         [0019]    First flow channel  101  includes a first effective cross-sectional area and extends from first end zone  105  arranged adjacent to fuel inlet  95  to a second end zone  106  through an intermediate portion  107 . Second flow channel  102  includes second effective cross-sectional area and extends from a first end zone  111  that is linked to second end zone  106  of first flow channel  101  to a second end zone  112  through an intermediate portion  113 . Third flow channel  103  includes a third effective cross-sectional area and extends from a first end zone  116  that is also linked to second end zone  106  of first flow channel  101  to a second end zone  117  through an intermediate portion  118 . Fourth flow channel includes a fourth effective cross-sectional area and extends from a first end zone  121  that is linked to second end zone  112  of second flow channel  102  and second end zone  117  of third flow channel  103  to a second end zone  122  through an intermediate portion  123 . 
         [0020]    The first, second, third, and fourth effective cross-sectional areas are distinct in order to provide desired pressures for first and second fuels to enhance combustion. More specifically, the first fuel is passed through second flow channel  102  having the second effective cross-section area in order to achieve desired pressure levels that promote more complete combustion of the first fuel, while the second fuel is passed through third flow channel  103  having the third effective cross-sectional area in order to achieve desired pressure levels that lead to more compete combustion of the second fuel. Of course it should be understood that the first and second fuels could be mixed, or a third fuel could be utilized and be passed through the second and third flow channels  102  and  103 . For example, the first and second fuels could be combined to form various fuel mixtures. 
         [0021]    In order to direct the first and second fuels to respective ones of the second and third flow channels  102  and  103 , a fluid, such as one of the first and second fuel, or diluents, is introduced at second end zone  106  of first flow channel  101 . As will be detailed more fully below, the fluid introduced at this point creates a Coand{hacek over (a)} effect that guides the one of the first and second fuels into the corresponding ones of the second and third flow channels  102  and  103 . More specifically, combustor fuel nozzle  20  includes a first control flow passage  130  that is configured and disposed to direct a control flow into second end zone  106  causing the second fuel to flow into third flow channel  103 , and a second control flow passage  131  that is configured and disposed to guide a second control flow into second end zone  106  causing the first fuel to flow into the second flow channel  102  as will be detailed more fully below. First and second control flow passages  130  and  131  are connected to a control flow circuit (not shown). In the exemplary embodiment shown, first control flow passage  130  is positioned opposite to second control flow passage  131 . However, it should be understood by one of ordinary skill in the art that first and second control flow passages  130  and  131  could be an angles relative to one another and/or first flow channel  101  or axially offset one from another. 
         [0022]    First control flow passage  130  includes a first end segment  134  that extends through body section  60  of inner nozzle portion  31  to a second end segment  135  that is fluidly connected with second end zone  106  of first flow channel  101 . Similarly, second control flow passage  131  includes a first end segment  139  that extends through body section  60  of inner nozzle portion  31  to a second end segment  140  that is fluidly connected to second end zone  106  of first flow channel  101 . With this arrangement, when the second fuel is introduced into fuel inlet  95 , a first fluid or control flow passing through first control flow passage  130  urges the second fuel to flow into third flow channel  103 . Similarly, when the first fuel is introduced into fuel inlet  95 , a second fluid or control flow passing through second control flow passage  131  urges the first fuel to flow into second flow channel  102 . As noted above, the first and second control flows can constitute the first and second fuels, diluents, other fluids, or combinations thereof. 
         [0023]    Reference will now be made to  FIG. 3  in describing a combustor fuel nozzle  152  constructed in accordance with another aspect of the exemplary embodiment. Combustor fuel nozzle  152  includes an outer nozzle portion  156  and an inner nozzle portion  158 . Outer nozzle portion  156  includes a body portion  160  having a first end portion  161  that extends to a second end portion  162 . Body portion  160  is further shown to include an outer wall  164  and an inner wall  165  that defines a plenum  168 . First end portion  161  defines an inlet portion  170  and second end portion  162  defines an outlet portion  171  having a plurality of openings  172 . As shown, inner nozzle portion  158  extends into outer nozzle portion  156 . More specifically, inner nozzle portion  158  extends through first end portion  161  into plenum  168  and is coupled to inner wall  165  in a manner that will be described more fully below. 
         [0024]    Inner nozzle portion  158  includes a body section  180  having a first end section  182  that extends to a second end section  183 . Body section  180  is also shown to include an outer wall  186  and an inner wall  187  that defines a plenum  190 . First end section  182  defines an inlet section  193 , and second end section  183  defines an outlet section  194  having a plurality of openings  195 . Inner nozzle portion  158  is connected to inner wall  165  of outer nozzle portion  156  through a circumferential flange  197  having first and second seal lands  199  and  200  provided with corresponding seals (not shown). In accordance with an exemplary embodiment, combustor fuel nozzle  152  further includes a dual fuel flow passages  204  that extends through inner nozzle portion  158 . As will become more fully evident below, combustor fuel nozzle  152  relies upon a Coand{hacek over (a)} effect to guide first and/or second fuels through dual fuel flow passage  204 . 
         [0025]    In accordance with an exemplary embodiment, dual fuel flow passage  204  includes a body  208  having a first end  211  that extends to a second end  212 . First end  211  defines a fuel inlet  215 , while second end  212  defines a fuel outlet  216  that extends though outlet section  194 . Dual fuel flow passage  204  includes a first flow channel  226  that extends from fuel inlet  215 , a second flow channel  227  that is fluidly coupled to first flow channel  226 , and a third flow channel  228  that is fluidly coupled to second flow channel  227  and fuel outlet  216 . 
         [0026]    First flow channel  226  includes a first effective cross-sectional area and extends from first end zone  231  arranged adjacent to fuel inlet  215  to a second end zone  232  through an intermediate portion  233 . Second flow channel  227  includes second effective cross-sectional area and extends from a first end zone  237  that is linked to second end zone  232  of first flow channel  226  to a second end zone  238  through an intermediate portion  239 . Third flow channel  228  includes a third effective cross-sectional area and extends from a first end zone  243  that is linked to second end zone  238  of second flow channel  227  to a second end zone  244  through an intermediate portion  245 . In accordance with the exemplary embodiment, the first, second, and third effective cross-sectional areas are similar but are selectively adjustable in order to provide desired pressures for first and second fuels to promote a more complete combustion. 
         [0027]    In order to promote desired pressures for the first and second fuels, dual fuel flow passage  204  includes a first control flow passage  260  and a second control passage  261  that direct first and second control flows to selectively adjust the effective cross-sectional areas of second flow channel  227 . In the exemplary embodiment shown, first control flow passage  260  is aligned with and positioned opposite to second control flow passage  261 . However, it should be understood by one of ordinary skill in the art that first and second control flow passages  260  and  261  could be arranged at angles relative to one another and/or second flow channel  227  or axially offset one from another. Dual fuel flow passage  204  also includes a third control flow passage  262  and a fourth control flow passage  263  that direct third and fourth control flows to selectively adjust the effective cross-sectional areas of third flow channel  228 . In the exemplary embodiment shown, third control flow passage  262  is aligned with and positioned opposite to fourth control flow passage  263 . However, it should be understood by one of ordinary skill in the art that third and fourth control flow passages  262  and  263  could be arranged at angles relative to one another and/or third flow channel  228  or axially offset one from another. First, second, third, and fourth control flow passages  260 - 263  are operatively connected to a control flow circuit (not shown) that delivers the control flow. The control flow includes the first fuel, the second fuel, diluents or combinations thereof. 
         [0028]    In a manner similar to that described above, third control flow passage  262  is aligned with and positioned opposite fourth control flow passage  263 . First control flow passage  260  includes a first end segment  270  that extends through body section  180  of inner nozzle portion  158  to a second end segment  271  that is fluidly connected with second end zone  232  of first flow channel  226 . Similarly, second control flow passage  261  includes a first end segment  273  that extends through body section  180  of inner nozzle portion  158  to a second end segment  274  that is fluidly connected with second end zone  232  of first flow channel  226 . Third control flow passage  262  includes a first end segment  276  that extends through body section  180  of inner nozzle portion  158  to a second end segment  277  that is fluidly connected with second end zone  238  of second flow channel  227 , and fourth control flow passage  263  includes a first end segment  280  that extends through body section  180  of inner nozzle portion  158  to a second end segment  281  that is fluidly connected with second end zone  238  of second flow channel  227 . 
         [0029]    With this arrangement, when the first fuel is introduced into fuel inlet  215 , first and second control flows are passed into first and second control flow passages  260  and  261 , respectively. The first and second control flows enter into second flow channel and, relying on the Coand{hacek over (a)} effect, pass along internal surfaces thereof to selectively adjust the effective cross-sectional area. Similarly, if desired, third and fourth control flows are passed through third and fourth control flow passages  262  and  263 , enter into third flow channel and, relying on the Coand{hacek over (a)} effect, pass along internal surfaces thereof to selectively adjust the effective cross-sectional area. In this manner, desired pressures are achieved for the first fuel in order to promote more complete combustion. When using the second fuel, the control flows are adjusted to achieve an effective cross-sectional area for the second and third flow channels  227  and  228  to establish desired pressures for the second fuel in order to promote more complete combustion. 
         [0030]    At this point it should be understood that the exemplary embodiment provides a fuel nozzle for a turbomachine that can be selectively operated using a wide range of wobbe fuels without requiring multiple nozzles, nozzle changes or expensive/complicated plumbing/valving. Moreover, the fuel nozzle in accordance with the exemplary embodiment can be selectively adjusted to achieve desired operating pressures thereby enabling turbomachine operation using syngas, diluted fuel streams or high wobbe fuels such as propane, butane and the like. The flexibility to use a wide range of fuels leads to lower NOx emissions without requirement of costly and complicated systems that allow for fuel changes. 
         [0031]    While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.