Abstract:
A fuel injector ( 23 ) comprises a cylindrical passage ( 32 ) which opens in a combustion chamber ( 26 ), a fuel introduction passage ( 34 ) which guides fuel to a region of the cylindrical passage ( 32 ) which is closer to the combustion chamber ( 26 ), and an air introduction passage ( 35 ) which guides compressed air to the cylindrical passage ( 32 ) at a location that is upstream of a location at which the fuel is introduced to the cylindrical passage ( 32 ), wherein the fuel introduction passage ( 34 ) guides the fuel in a tangential direction of the cylindrical passage ( 32 ) in a transverse sectional view.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a fuel injector and a gas turbine. 
       BACKGROUND ART 
       [0002]    For environment protection purposes, it is desirable to reduce a nitrogen oxide (NOx) exhausted from a gas turbine. As a method of reducing the exhaust amount of NOx, there is a method in which fuel and compressed air are fully mixed (perfectly pre-mixed), and the resulting air-fuel mixture is injected from a fuel injector and combusted. In accordance with this method, since combustion is performed quickly, an increase in a combustion temperature can be suppressed. Therefore, generation of NOx (thermal NOx) due to the increase in the combustion temperature can be suppressed (see Patent Literature 1). 
       CITATION LIST 
     Patent Literature 
       [0003]    Patent Literature 1: Japanese Laid-Open Patent Application Publication No. 2010-216668 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0004]    If the fuel and the compressed air are pre-mixed in large amounts in the interior of the fuel injector, a “flashback flame” may occur, in which a flame propagates from a combustion chamber to the fuel injector, and cause burning damages to the fuel injector. In particular, in a case where a gas with a high reactivity, such as a hydrogen gas, is used as the fuel, the flashback flame tends to occur. 
         [0005]    In view of the above-described circumstances, the present invention has been developed. An object of the present invention is to provide a fuel injector which can reduce the generation amount of NOx and suppress the occurrence of a flashback flame. 
       Solution to Problem 
       [0006]    A fuel injector of the present invention comprises a cylindrical passage which opens in a combustion chamber; a fuel introduction passage which guides fuel to a region of the cylindrical passage which is closer to the combustion chamber; and an air introduction passage which guides compressed air to the cylindrical passage at a location that is upstream of a location at which the fuel is introduced to the cylindrical passage, wherein the fuel introduction passage guides the fuel in a tangential direction of the cylindrical passage in a transverse sectional view. 
         [0007]    In accordance with this configuration, the fuel is injected into the combustion chamber while swirling along the inner peripheral surface of the cylindrical passage, and is formed in a sheet shape (a spiral band shape) in the interior of the combustion chamber. At this time, the surface area of the fuel as a series of substances is large, and a distance between the outer surface of the fuel and the center of the fuel is short. This makes it possible to shorten combustion reaction time, and reduce the generation amount of NOx. Since the compressed air flows from the cylindrical passage toward the combustion chamber, it becomes possible to suppress a combustion gas from becoming stagnant in the vicinity of the exit of the cylindrical passage, and stable combustion can be carried out. Further, since the fuel and the air are not pre-mixed in large amounts in the interior of the fuel injector, the occurrence of a flashback flame can be suppressed. 
         [0008]    In the above-described fuel injector, the air introduction passage may have a configuration which causes the compressed air to swirl in the same direction as a direction in which the fuel swirls, in an interior of the cylindrical passage. In accordance with this configuration, the swirling of the fuel is facilitated by the swirling compressed air. Therefore, the fuel can be formed in the sheet shape with a higher reliability. 
         [0009]    In the above-described fuel injector, the fuel introduction passage may guide the fuel in a direction that is inclined toward the combustion chamber with respect to a direction perpendicular to a center axis of the cylindrical passage. In accordance with this configuration, hydrogen is less likely to become stagnant in the vicinity of the exit of the cylindrical passage. Therefore, the risk of occurrence of the flashback flame can be reduced even when a gas with a high reactivity, such as a hydrogen gas, is used. 
         [0010]    According to another aspect of the present invention, a fuel injector comprises a plurality of cylindrical passages which open in a combustion chamber; a plurality of fuel introduction passages which guide fuel to regions of the plurality of cylindrical passages, respectively, which are closer to the combustion chamber; and a plurality of air introduction passages which guide compressed air to the plurality of cylindrical passages, respectively, at locations that are upstream of locations at which the fuel is introduced to the plurality of cylindrical passages, wherein the fuel introduction passages guide the fuel in tangential directions of the cylindrical passages, in transverse sectional views, respectively. 
         [0011]    A gas turbine of the present invention comprises any one of the above-described fuel injectors. 
       Advantageous Effects of Invention 
       [0012]    As described above, in accordance with the above-described fuel injector, it becomes possible to reduce the generation amount of NOx and suppress the occurrence of a flashback flame. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0013]      FIG. 1  is a view schematically showing the overall configuration of a gas turbine. 
           [0014]      FIG. 2  is a view schematically showing the configuration of a combustor. 
           [0015]      FIG. 3  is a perspective view of a supplemental fuel injector. 
           [0016]      FIG. 4  is a longitudinal sectional view of the supplemental fuel injector. 
           [0017]      FIG. 5  is a cross-sectional view taken in the direction of arrows along line A-A of  FIG. 4 , showing a first fuel introduction passage. 
           [0018]      FIG. 6  is a cross-sectional view taken in the direction of arrows along line A-A of  FIG. 4 , showing a second fuel introduction passage. 
           [0019]      FIG. 7  is a cross-sectional view taken in the direction of arrows along line A-A of  FIG. 4 , showing a third fuel introduction passage. 
           [0020]      FIG. 8  is a cross-sectional view taken in the direction of arrows along line B-B of  FIG. 4 . 
           [0021]      FIG. 9  is a cross-sectional view taken in the direction of arrows along line C-C of  FIG. 4 . 
           [0022]      FIG. 10  is a view showing a positional relationship between the fuel introduction passage and an air introduction passage. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0023]    Hereinafter, the embodiment of the present invention will be described with reference to the drawings. Throughout the drawings, the same or corresponding components are designated by the same reference symbols and will not be described repeatedly. 
         [0024]    &lt;Configuration of Gas Turbine&gt; 
         [0025]    First of all, the overall configuration of a gas turbine  100  will be described.  FIG. 1  is a view schematically showing the configuration of the gas turbine  100 . The gas turbine  100  of the present embodiment is a gas turbine for power generation, which drives a power generator  101 . The gas turbine  100  includes a compressor  10 , a combustor  11 , a fuel supply device  12 , and a turbine  13 . 
         [0026]    Compressed air  102  is supplied from the compressor  10  to the combustor  11 . Fuel  103  is supplied from the fuel supply device  12  to the combustor  11 . In the present embodiment, it is supposed that a hydrogen gas with a high reactivity is used as the fuel  103 . Alternatively, the fuel  103  may be a natural gas, liquefied hydrogen, or the like. In the interior of the combustor  11 , the fuel  103  and the compressed air  102  are combusted. A combustion gas  104  in a high-temperature and high-pressure state generated by the combustion is supplied to the turbine  13 . The turbine  13  rotates by energy of the combustion gas  104  and drives the power generator  101  via the compressor  10 . 
         [0027]    &lt;Configuration of Combustor&gt; 
         [0028]    Next, the combustor  11  will be described more specifically.  FIG. 2  is a cross-sectional view schematically showing the combustor  11 . The combustor  11  of the present embodiment is of a reverse flow can type in which the compressed air  102  and the combustion gas  104  flow in opposite directions. The combustor  11  includes a housing  20 , a combustion tube  21 , a main fuel injector  22 , and supplemental fuel injectors  23 . Alternatively, the combustor  11  may have a structure different from the reverse flow can type. 
         [0029]    The housing  20  is a member defining the contour of the combustor  11 . The housing  20  includes a cylindrical outer pipe member  24 , and a disc-shaped end cover  25  provided at an end portion of the outer pipe member  24  on a first side (left side in  FIG. 2 ). 
         [0030]    The combustion tube  21  is housed inside the housing  20 . A combustion chamber  26  is formed inside the combustion tube  21 . In the interior of the combustion chamber  26 , the fuel  103  and the compressed air  102  are combusted to generate the combustion gas  104 . The generated combustion gas  104  flows to the right side in  FIG. 2  and is supplied to the turbine  13  (see  FIG. 1 ). Between the combustion tube  21  and the housing  20 , an annular air passage  27  is formed. The compressed air  102  supplied from the compressor  10  flows through the air passage  27  and toward the main fuel injector  22  (toward the left side in  FIG. 1 ). 
         [0031]    The main fuel injector  22  is mounted to the end cover  25  of the housing  20  to extend through the air passage  27  in the axial direction of the combustor  11 . The main fuel injector  22  is configured to take in the compressed air  102  which has flowed through the air passage  27 . The main fuel injector  22  injects the fuel  103  supplied from the fuel supply device  12  and the taken-in compressed air  102  into the combustion chamber  26  at the same time. Although in  FIG. 2 , one main fuel injector  22  is shown, a plurality of main fuel injectors  22  may be provided. Further, a pilot fuel injector which injects the fuel in a small amount may be provided, separately from the main fuel injector  22 . 
         [0032]    The supplemental fuel injectors  23  are mounted to the outer pipe member  24  of the housing  20  to extend through the air passage  27  in the radial direction of the combustor  11 . The supplemental fuel injectors  23  are configured to be capable of taking in a part of the compressed air  102  flowing through the air passage  27 . The supplemental fuel injectors  23  inject the fuel  103  supplied from the fuel supply device  12  and the taken-in compressed air  102  into the combustion chamber  26  at the same time. In the present embodiment, the plurality of supplemental fuel injectors  23  are arranged at equal intervals (e.g., intervals of 90 degrees) in the circumferential direction of the combustor  11 . 
         [0033]    &lt;Configuration of Fuel Injector&gt; 
         [0034]    Next, the configurations of the supplemental fuel injectors  23  will be described in detail. Each of the supplemental fuel injectors  23  of the present embodiment is a fuel injector which injects the fuel  103  in a sheet shape (hereinafter this fuel injector will be referred to as the fuel injector which uses “sheet injection method”). Although a case where the supplemental fuel injectors  23  are the fuel injectors which use the sheet injection method will be described below, both the main fuel injector  22  and the supplemental fuel injectors  23  may be the fuel injectors which use the sheet injection method, or only the main fuel injector  22  may be the fuel injector which uses the sheet injection method. 
         [0035]      FIG. 3  is a perspective view of the supplemental fuel injector  23 .  FIG. 4  is a longitudinal sectional view of the supplemental fuel injector  23 . As shown in  FIG. 3 , the supplemental fuel injector  23  includes a first cylindrical section  30  located on a base end side (right upper side in  FIG. 3 ), and a second cylindrical section  31  located on a tip end side (left lower side in  FIG. 3 ) and having a diameter larger than that of the first cylindrical section  30 . 
         [0036]    As shown in  FIG. 4 , the supplemental fuel injector  23  includes a plurality of cylindrical passages  32  extending in the axial direction of the supplemental fuel injector  23 , a fuel passage  33 , a plurality of fuel introduction passages  34 , and a plurality of air introduction passages  35 . 
         [0037]    The cylindrical passages  32  are passages which introduce the fuel  103  and the compressed air  102  into the combustion chamber  26 , while the fuel  103  and the compressed air  102  are swirling. The cylindrical passages  32  open in the combustion chamber  26 . As shown in  FIG. 3 , among the plurality of cylindrical passages  32 , six inner cylindrical passages  32 A are arranged in the circumferential direction around the center axis of the supplemental fuel injector  23 , while twelve outer cylindrical passages  32 B are arranged in the circumferential direction around the center axis of the supplemental fuel injector  23  and located outward relative to the inner cylindrical passages  32 A. 
         [0038]    As shown in  FIG. 4 , the inner cylindrical passages  32 A are formed to extend over the first cylindrical section  30  and the second cylindrical section  31 , while the outer cylindrical passages  32 B are formed to extend only in the second cylindrical section  31 . Although in the present embodiment, the cylindrical passages  32  extend in parallel with each other, the cylindrical passages  32  may not necessarily extend in parallel with each other. For example, only the inner cylindrical passages  32 A may extend in the axial direction, while the outer cylindrical passages  32 B may extend radially outward to be inclined with respect to the axial direction. 
         [0039]    The fuel passage  33  is a passage which delivers the fuel  103  supplied from the fuel supply device  12  (see  FIG. 1 ) to the plurality of fuel introduction passages  34  which branch from the fuel passage  33 . As shown in  FIG. 4 , the fuel passage  33  is located on the center axis of the supplemental fuel injector  23  and extends in the axial direction. As shown in  FIG. 4 , the inner peripheral surface of the fuel passage  33  is formed with six fuel discharge ports  36  at equal intervals in the circumferential direction at three different axial locations. The fuel introduction passages  34  are connected to the fuel discharge ports  36 , respectively. In this structure, the fuel  103  in the interior of the fuel passage  33  flows to the fuel introduction passages  34  through the fuel discharge ports  36 . Although in the present embodiment, only one fuel passage  33  is formed, a plurality of fuel passages  33  may be formed. 
         [0040]    The fuel introduction passages  34  are passages which guide the fuel  103  to the cylindrical passages  32 . In the description below, the fuel introduction passages  34  will be referred to as “first fuel introduction passages  34 A”, “second fuel introduction passages  34 B”, and “third fuel introduction passages  34 C”, respectively, in the order in which a distance between the fuel discharge ports  36  to which the fuel introduction passages  34  are connected and the combustion chamber  26  decreases.  FIGS. 5 to 7  are cross-sectional views taken in the direction of arrows along line A-A of  FIG. 4 , showing the first fuel introduction passages  34 A, the second fuel introduction passages  34 B, and the third fuel introduction passages  34 C, respectively. 
         [0041]    As shown in  FIG. 5 , the first fuel introduction passages  34 A extend from the fuel passage  33  to the six outer cylindrical passages  32 B, respectively, among the twelve outer cylindrical passages  32 B. The downstream end portions of the first fuel introduction passages  34 A are connected to the outer cylindrical passages  32 B, respectively in such a manner that the downstream end portions of the first fuel introduction passages  34 A extend in the tangential directions of the cylindrical passages  32 , in cross-sectional views, respectively. The downstream end portions of the first fuel introduction passages  34 A extend substantially in parallel with the radial direction of the supplemental fuel injector  23 . 
         [0042]    As shown in  FIG. 6 , the second fuel introduction passages  34 B extend from the fuel passage  33  to the six outer cylindrical passages  32 B, respectively, to which the first fuel introduction passages  34 A are not connected, among the twelve outer cylindrical passages  32 B. In the present embodiment, the outer cylindrical passages  32 B are provided in such a manner that the outer cylindrical passage  32 B to which the first fuel introduction passage  34 A is connected and the outer cylindrical passage  32 B to which the second fuel introduction passage  34 B is connected are arranged alternately in the circumferential direction of the supplemental fuel injector  23 . The downstream end portions of the second fuel introduction passages  34 B are connected to the outer cylindrical passages  32 B, respectively in such a manner that the downstream end portions of the second fuel introduction passages  34 B extend in the tangential directions of the outer cylindrical passages  32 B, in cross-sectional views, respectively. Note that the downstream end portions of the second fuel introduction passages  34 B extend in a direction that is inclined with respect to the radial direction of the supplemental fuel injector  23 , differently from the downstream end portions of the first fuel introduction passages  34 A. 
         [0043]    As shown in  FIG. 7 , the third fuel introduction passages  34 C extend from the fuel passage  33  to the six inner cylindrical passages  32 A, respectively. The downstream end portions of the third fuel introduction passages  34 C are connected to the inner cylindrical passages  32 A, respectively in such a manner that the downstream end portions of the third fuel introduction passages  34 C extend in the tangential directions of the inner cylindrical passages  32 A, in cross-sectional views, respectively. The downstream end portions (fuel injection ports  40 ) of the first fuel introduction passages  34 A, the downstream end portions (fuel injection ports  40 ) of the second fuel introduction passages  34 B, and the downstream end portions (fuel injection ports  40 ) of the third fuel introduction passages  34 C are located in the regions of the cylindrical passages  32  which are close to the combustion chamber  26 . The phrase “the regions located in the cylindrical passages  32  which are close to the combustion chamber  26 ” may be the regions closest to the combustion chamber  26  in a case where the cylindrical passages  32  are equally divided into three regions in the axial direction or the regions closest to the combustion chamber  26  in a case where the cylindrical passages  32  are equally divided into two regions in the axial direction. 
         [0044]    As described above, the downstream end portions of all of the fuel introduction passages  34  are connected to the cylindrical passages  32 , respectively in such a manner that the downstream end portions of the fuel introduction passages  34  extend in the tangential directions of the cylindrical passages  32 , in the cross-sectional views, respectively. In this structure, the fuel  103  is introduced to the cylindrical passages  32  from the tangential directions of the cylindrical passages  32 , in the cross-sectional views (transverse sectional views) perpendicular to the center axes of the cylindrical passages  32 . Thus, the fuel  103  having been introduced into the cylindrical passages  32  swirl (swirl in a clockwise direction in  FIGS. 5 to 7 ) along the inner peripheral surfaces of the cylindrical passages  32 , and thereafter are injected into the combustion chamber  26 . In this way, the fuel  103  swirl along the inner peripheral surfaces of the cylindrical passages  32 , and thereby is formed in the sheet shape. 
         [0045]    As shown in  FIG. 4 , the first fuel introduction passages  34 A include first longitudinal passage sections  37  extending in the axial direction, respectively, while the second fuel introduction passages  34 B include second longitudinal passage sections  38 , respectively, which extend in the axial direction, respectively, and are shorter than the first longitudinal passage sections  37 . On the other hand, the third fuel introduction passages  34 C do not include passage sections extending in the axial direction. With this configuration of the fuel introduction passages  34 , in all of the cylindrical passages  32 , the fuel injection ports  40  through which the fuel  103  is introduced to the cylindrical passages  32  are located at a substantially equal distance from the exits of the cylindrical passages  32 . 
         [0046]    The air introduction passages  35  are passages which guide the compressed air  102  to the cylindrical passages  32 . As shown in  FIG. 3 , the first cylindrical section  30  is formed with air inlets  41 A for the inner cylindrical passages  32 A, while the second cylindrical section  31  is formed with air inlets  41 B for the outer cylindrical passages  32 B. The air inlets  41 A,  41 B extend in the axial direction and are formed in a slit shape. As shown in  FIG. 4 , the air introduction passages  35  connect the air inlets  41 A formed in the first cylindrical section  30  to the inner cylindrical passages  32 A, and connect the air inlets  41 B formed in the second cylindrical section  31  to the outer cylindrical passages  32 B. In this structure, the compressed air  102  outside the supplemental fuel injectors  23  can be introduced to the cylindrical passages  32 . 
         [0047]    As shown in  FIG. 4 , the air introduction passages  35  are located upstream of the fuel injection passages  34  (the fuel injection ports  40 ). In this structure, the compressed air  102  is guided to the regions of the cylindrical passages  32  that are upstream of the regions of the cylindrical passages  32  to which the fuel  103  is introduced. Therefore, the fuel  103  is injected into the combustion chamber  26  together with the compressed air  102  in such a manner that the fuel  103  is pushed out by the compressed air  102 . 
         [0048]      FIG. 8  is a cross-sectional view taken in the direction of arrows along line B-B of  FIG. 4 .  FIG. 9  is a cross-sectional view taken in the direction of arrows along line C-C of  FIG. 4 . As shown in  FIGS. 8 and 9 , the air introduction passages  35  are connected to the cylindrical passages  32 , respectively in such a manner that the air introduction passages  35  extend in the tangential directions of the cylindrical passages  32 , in cross-sectional views, respectively. Therefore, in cross-sectional views (transverse sectional views) perpendicular to the center axes of the cylindrical passages  32 , the compressed air  102  can be guided to the cylindrical passages  32  from the tangential directions of the cylindrical passages  32 , respectively. Thus, the compressed air  102  having been introduced to the cylindrical passages  32  is injected into the combustion chamber  26  while swirling (swirling in the clockwise direction in  FIGS. 8 and 9 ) along the inner peripheral surfaces of the cylindrical passages  32 . 
         [0049]      FIG. 10  is a view showing a positional relationship between the fuel introduction passage  34  and the air introduction passage  35 , when viewed from the perspective of the combustion chamber  26 . In the example of  FIG. 10 , the fuel introduction passage  34  is connected to the right side of the cylindrical passage  32  in  FIG. 10 , while the air introduction passage  35  is connected to the lower side of the cylindrical passage  32  in  FIG. 10 . The fuel  103  is introduced to the right side of the cylindrical passage  32  in  FIG. 10  through the lower side in  FIG. 10 , and swirls in a counterclockwise direction along the inner peripheral surface of the cylindrical passage  32 . In contrast, the compressed air  102  is introduced to the lower side of the cylindrical passage  32  in  FIG. 10  through the left side in  FIG. 10 , and swirls in the counterclockwise direction along the inner peripheral surface of the cylindrical passage  32 . In this way, in the present embodiment, the compressed air  102  swirls in the same direction as that of the fuel  103 . Therefore, in the present embodiment, the fuel  103  can swirl more easily and hence can be formed in the sheet shape more easily, as compared to, for example, a case where the compressed air  102  flows linearly in the axial direction. 
         [0050]    Each of the air introduction passages  35  extends in a direction perpendicular to the center axis of the cylindrical passage  32 . Unlike in the case of the fuel  103 , even when the compressed air  102  which is swirling and the compressed air  102  which is introduced to the cylindrical passage  32  interfere with each other, this affects less the formation of the fuel  103  in the sheet shape. 
         [0051]    The present embodiment has been described above. As described above, since the fuel  103  is formed in the sheet shape in the present embodiment, a distance between the outer surface of the fuel  103  and the center of the fuel  103  is short, and combustion reaction time of the fuel  103  is short. As a result, generation of NOx can be suppressed. 
         [0052]    Although in the above-described embodiment, the air introduction passages  35  are connected to the cylindrical passages  32 , respectively in such a manner that the air introduction passages  35  extend in the tangential directions of the cylindrical passages  32 , in transverse sectional views, respectively, so that the compressed air  102  swirls in the same direction as that of the fuel  103  in the interiors of the cylindrical passages  32 , the configuration of the air introduction passages  35  is not limited to this. For example, the air introduction passages  35  may include swirlers provided on the outer peripheries of the cylindrical passages  32 , respectively to allow the compressed air  102  to swirl in the same direction as that of the fuel  103  in the interiors of the cylindrical passages  32 . 
         [0053]    Although in the above-described embodiment, the fuel injector  23  includes the plurality of cylindrical passages  32 , the plurality of fuel introduction passages  34 , and the plurality of air introduction passages  35 , the fuel injector  23  may not include the plurality of these passages. For example, the fuel injector  23  may include one cylindrical passage  32 , one fuel introduction passage  34  and one air introduction passage  35 . 
         [0054]    Although in the above-described embodiment, the cylindrical passages  32 , the fuel passage  33 , and the fuel introduction passages  34  are formed in the first cylindrical section  30  and the second cylindrical section  31 , the passages  32  to  34  may not be formed in the same members. For example, the passages  32  to  34  may be formed by independent pipe members, respectively, and coupled to each other to construct the fuel injector  23 . 
         [0055]    Although in the above-described embodiment, the fuel injector  23  is used in the gas turbine  100 , the fuel injector  23  may be used in a boiler, an absorption chiller, or the like, as well as the gas turbine. 
       INDUSTRIAL APPLICABILITY 
       [0056]    In accordance with the fuel injector of the present invention, the generation amount of NOx can be reduced, and the occurrence of a flashback flame can be suppressed. Therefore, the fuel injector of the present invention is useful in the technical field of the fuel injector. 
       REFERENCE SIGNS LIST 
       [0000]    
       
         
           
               22  main fuel injector 
               23  supplemental fuel injector 
               26  combustion chamber 
               32  cylindrical passage 
               32 A inner cylindrical passage 
               32 B outer cylindrical passage 
               34  fuel introduction passage 
               34 A first fuel introduction passage 
               34 B second fuel introduction passage 
               34 C third fuel introduction passage 
               35  air introduction passage 
               40  fuel introduction port 
               100  gas turbine 
               102  compressed air 
               103  fuel