Patent Publication Number: US-8112999-B2

Title: Turbomachine injection nozzle including a coolant delivery system

Description:
This invention was made with Government support under Contract No. DE-FC26-05NT4263, awarded by the US Department of Energy (DOE). The Government has certain rights in this invention. 
    
    
     BACKGROUND OF THE INVENTION 
     Exemplary embodiments of the present invention relate to the art of turbomachine injection nozzles and, more particularly, to turbomachine injection nozzles including a coolant delivery system. 
     In general, gas turbine engines combust a fuel/air mixture which releases heat energy to form a high temperature gas stream. The high temperature gas stream is channeled to a turbine via a hot gas path. The turbine converts thermal energy from the high temperature gas stream to mechanical energy that rotates a turbine shaft. The turbine may be used in a variety of applications, such as for providing power to a pump or an electrical generator. 
     In a gas turbine, engine efficiency increases as combustion gas stream temperatures increase. Unfortunately, higher gas stream temperatures produce higher levels of nitrogen oxide (NOx), an emission that is subject to both federal and state regulation. Therefore, there exists a careful balancing act between operating gas turbines in an efficient range, while also ensuring that the output of NOx remains below mandated levels. One method of achieving low NOx levels is to ensure good mixing of fuel and air prior to combustion. However certain fuels, such as hydrogen and syngas, have a high flame speed, particularly when burned in a pre-mixed mode. The high flame speed often results in flame holding that detracts from operating efficiency and has a negative impact on operational life of turbine components. 
     BRIEF DESCRIPTION OF THE INVENTION 
     In accordance with an exemplary embodiment of the invention, an injection nozzle for a turbomachine includes a main body having a first end portion that extends to a second end portion defining an exterior wall having an outer surface. The injection nozzle also includes a plurality of fluid delivery tubes extending through the main body. Each of the plurality of fluid delivery tubes includes a first inlet for receiving a first fluid, a second inlet for receiving a second fluid and an outlet. The outlet is arranged at the exterior wall. The injection nozzle further includes a coolant delivery system arranged within the main body. The coolant delivery system guides a coolant along at least one of a portion of the exterior wall to cool the outer surface and around the plurality of fluid delivery tubes. 
     In accordance with another exemplary embodiment of the invention, a method of cooling an injection nozzle for a turbomachine includes guiding a first fluid into a plurality of fluid delivery tubes extending through a main body of the injection nozzle, passing a second fluid toward the plurality of fluid delivery tubes, and delivering the first and second fluids through an exterior wall of the injection nozzle. The method further includes passing a coolant along at least one of a portion of the exterior wall and around the plurality of fluid delivery tubes. 
     In accordance with still another exemplary embodiment of the invention, a turbomachine includes a compressor, a combustor operatively connected to the compressor, and an injection nozzle operatively connected to the combustor. The injection nozzle includes a main body having a first end portion that extends to a second end portion defining an exterior wall having an outer surface. The injection nozzle also includes a plurality of fluid delivery tubes extending through the main body. Each of the plurality of fluid delivery tubes includes a first fluid inlet for receiving a first fluid, a second fluid inlet for receiving a second fluid and an outlet. The outlet being arranged at the exterior wall. The injection nozzle further includes a coolant delivery system arranged within the main body. The coolant delivery system guides a coolant along at least one of a portion of the exterior wall to cool the outer surface and around the plurality of fluid delivery tubes. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional side view of an exemplary gas turbine engine including an injection nozzle constructed in accordance with an exemplary embodiment of the invention; 
         FIG. 2  is a cross-sectional side view of an injection nozzle constructed in accordance with an exemplary embodiment of the invention; and 
         FIG. 3  is a cross-sectional side view of an injection nozzle constructed in accordance with another exemplary embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is a schematic illustration of an exemplary gas turbine engine  2 . Engine  2  includes a compressor  4  and a combustor assembly  8 . Combustor assembly  8  includes a combustor assembly wall  10  that at least partially defines a combustion chamber  12 . A pre-mixing apparatus or injection nozzle  14  extends through combustor assembly wall  10  and leads into combustion chamber  12 . As will be discussed more fully below, injection nozzle  14  receives a first fluid or fuel through a fuel inlet  18  and a second fluid or compressed air from compressor  4 . The fuel and compressed air are mixed, passed into combustion chamber  12  and ignited to form a high temperature, high pressure combustion product or air stream. Although only a single combustor assembly  8  is shown in the exemplary embodiment, engine  2  may include a plurality of combustor assemblies  8  arranged in, for example, a can annular array. In any event, engine  2  also includes a turbine  30  operatively connected to a compressor/turbine shaft  34  (sometimes referred to as a rotor). Turbine  30  drives, shaft  34  that, in turn, drives compressor  4 . 
     In operation, air flows into compressor  4  and is compressed into a high pressure gas. The high pressure gas is supplied to combustor assembly  8  and mixed with fuel, for example process gas and/or synthetic gas (syngas), in injection nozzle  14 . The fuel/air or combustible mixture is then passed into combustion chamber  12  and ignited to form a high pressure, high temperature combustion gas stream. In addition to process gas and syngas, combustor assembly  8  can combust fuels that include, but are not limited to natural gas and/or fuel oil. In any event, combustor assembly  8  channels the combustion gas stream to turbine  30  which coverts thermal energy to mechanical, rotational energy. 
     Reference will now be made to  FIG. 2  in describing an injection nozzle  14  constructed in accordance with a first exemplary embodiment of the invention. As shown, injection nozzle  14  includes a main body  40  having a first end portion  42  that extends through an intermediate portion  43  to a second end portion  44 . Second end portion  44  defines an exterior wall  45  having an outer surface  46 . As will be discussed more fully below, injection nozzle  14  includes a first plenum  48  arranged within main body  40  adjacent first end portion  42  and a second plenum  49  arranged within main body  40  adjacent second end portion  44 . Injection nozzle  14  is further shown to include a plurality of fluid delivery tubes, one of which is indicated at  60 . Each fluid delivery tube  60  includes a first end section  64  that extends to a second end section  65  through an intermediate section  66 . First end section  64  defines a first fluid inlet  69  while second end section  65  defines an outlet  71 . 
     Injection nozzle  14  also includes a second fluid delivery system  80 . Second fluid delivery system  80  includes a second fluid delivery member  82  that is fluidly connected to first plenum  48  that, in turn, is fluidly connected to a second fluid inlet  85  provided in each of the plurality of fluid delivery tubes  60 . More specifically, each fluid delivery tube  60  includes a second fluid inlet  85 , shown in the form of orifices or holes, formed in intermediate section  66 . With this arrangement, a first fluid, generally air, is introduced through first fluid inlet  69  to each fluid delivery tube  60 . A second fluid, generally fuel, is passed through second fluid delivery member  82  and into first plenum  48 . The fuel flows around the plurality of fluid delivery tubes  60  and passes through each second fluid inlet  85  to mix with the air to form a fuel air mixture. The fuel air mixture passes from outlet  71  and is ignited to form high temperature, high pressure gases that are delivered to turbine  30 . In order to minimize flame holding at exterior wall  45  thereby allowing the use of lower velocity air streams, injection nozzle  14  includes a coolant delivery system  94 . 
     In accordance with the exemplary embodiment shown, coolant delivery system  94  includes a coolant inlet  97  and a coolant outlet  98  each of which are fluidly connected to second plenum  49 . Second plenum  49  extends about or enveloped each of the plurality of fluid delivery tubes  60  as well as along internal surfaces (not separately labeled) of exterior wall  45 . With this construction, coolant, typically in the form of water, is passed through coolant inlet  97  to second plenum  49 . The coolant flows around each of the plurality of fluid delivery tubes  60  as well as adjacent an inner portion (not separately labeled) of exterior wall  45 . The coolant than passes out from coolant outlet  98  and through a heat exchanger (not shown) prior to being re-introduced into coolant inlet  97 . In this manner, the coolant flowing through plenum  49  lowers temperatures of plurality of fluid delivery tubes  60  and thereby enhances tube wall flame quench capability and flam flash back resistance. In addition, the coolant flowing near exterior wall  45  lowers local temperatures at outer surface  46  to provide an additional quench effect. The quench effect reduces flame holding, substantially prevents flash back and minimizes thermal cracking. 
     Reference will now be made to  FIG. 3  in describing an injection nozzle  114  constructed in accordance with another exemplary embodiment of the invention. As shown, injection nozzle  114  includes a main body  140  having a first end portion  142  that extends through an intermediate portion  143  to a second end portion  144 . Second end portion  144  defines an exterior wall  145  having an outer surface  146 . As will be discussed more fully below, injection nozzle  114  includes a first plenum  148  arranged within main body  140  adjacent first end portion  142  and a second plenum  149  arranged within main body  140  adjacent second end portion  144 . Injection nozzle  114  is further shown to include a plurality of fluid delivery tubes, one of which is indicated at  160 . Each fluid delivery tube  160  includes a first end section  164  that extends to a second end section  165  through an intermediate section  166 . First end section  164  defines a first fluid inlet  169  while second end section  165  defines an outlet  171 . 
     Injection nozzle  14  also includes a second fluid delivery system  80 . Second fluid delivery system  80  includes a fluid delivery conduit  185  having a first section  187  and a second section  189 . First section  187  envelops second section  189  and is fluidly connected to first plenum  148  that, in turn, is fluidly connected to a second fluid inlet  191  provided in each of the plurality of fluid delivery tubes  160 . More specifically, each fluid delivery tube  160  includes a second fluid inlet  191 , shown in the form of an orifice, formed in intermediate section  166 . In a manner similar to that described above, a first fluid, generally air, is introduced through first fluid inlet  169  to each fluid delivery tube  160 . A second fluid, generally fuel, is passed through first section  187  of fluid delivery conduit  185  and into first plenum  148 . The fuel flows around the plurality of fluid delivery tubes  160  and passes through each second fluid inlet  191  to mix with the air and form a fuel air mixture. The fuel/air mixture passes from outlet  171  and is ignited to form high temperature, high pressure gases that are delivered to turbine  30 . In order to minimize flame holding at exterior wall  145  thereby allowing the use of lower velocity air streams, injection nozzle  114  also includes a coolant delivery system  193 . 
     Coolant delivery system  193  includes an inlet  195  that is fluidly connected to second section  189  of fluid delivery conduit  185  and second plenum  149 . Coolant delivery system  193  also includes a coolant outlet  196 . With this arrangement, coolant, typically in the form of water, is passed through second section  189  of fluid delivery conduit  185 , through coolant inlet  195  and into second plenum  149 . The coolant flows around each of the plurality of fluid delivery tubes  160  as well as adjacent an inner portion (not separately labeled) of exterior wall  145 . The coolant then passes out from coolant outlet  196  and through a heat exchanger (not shown) prior to being re-introduced into coolant delivery system  193 . In this manner, the coolant flowing around through second fluid plenum  149  lowers temperatures of the plurality of fluid delivery tubes  160  and thereby provides better tube wall flame quench effects and enhances nozzle flame flashback resistance. In addition, the coolant flowing near exterior wall  145  lowers local temperatures to provide an additional quench effect. The quench effect reduces flame holding, substantially prevents flash back, and minimizes thermal cracking. 
     In general, 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 exemplary embodiments of the present invention 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.