Patent Publication Number: US-9851098-B2

Title: Swirler

Description:
TECHNICAL FIELD 
     The inventive concept relates to a swirler. 
     BACKGROUND ART 
     A swirler is used as a flame stabilizer of a pressure atomizing-type oil burner or a high pressure gas current atomizing-type oil burner, and swirls the air introduced into a burner by using swirl vanes. A mixture gas of the air introduced into the burner by the swirler and a fuel generates negative pressure in a center portion, and accordingly, generates a high temperature low-speed circulation region that may be ignited. 
     Swirlers may be classified as axial flow swirlers and radial flow swirlers. 
       FIG. 1  is a partially cut perspective view schematically showing an axial flow swirler, as an example of an axial flow swirler. In addition,  FIG. 2  is a cross-sectional view of the axial flow swirler of  FIG. 1 , wherein a side of the axial flow swirler based on a symmetric axis is shown. Referring to  FIGS. 1 and 2 , an axial flow swirler  10  includes a plurality of vanes  12  that are disposed on an upstream side of a burner  50  on a path of air GA entering a chamber  51  of the burner  50 . The plurality of vanes  12  are radially arranged on a boundary of a pilot body  15  to be inclined with respect to an entering path of the air GA so as to change a flow direction of the air entering the chamber  51  of the burner  50 . Therefore, the air and the fuel mixed with the air are introduced into the burner while generating a whirlpool. 
     Such an axial flow swirler has a simple structure and is easy to be manufactured. However, because only a direction of introduction fluid is changed without changing a velocity of the introduction fluid, the performance of mixing the air and the fuel may degrade. 
       FIG. 3  shows an example of a radial flow swirler and schematically shows a cross-sectional side of the radial flow swirler based on a symmetric axis. A radial flow swirler  20  is disposed at an upstream side of a burner  50  like the axial flow swirler  10 , and includes a pilot body  25  and a plurality of vanes  22  coupled to the pilot body  25 . Unlike the axial flow swirler  10 , in the radial flow swirler  20 , the air GA is introduced into the chamber  51  of the burner  50  in a radial direction while a flow direction and velocity of the air are rapidly changed by the vanes  22 . 
     As described above, the radial flow swirler is excellent in view of mixing the air and the fuel due to the rapid change in the velocity of the introduced air, but it is difficult to manufacture the radial flow swirler and to control the flow of fluid, compared to the axial flow swirler. 
     DETAILED DESCRIPTION OF THE INVENTIVE CONCEPT 
     Technical Problem 
     The inventive concept provides a swirler having excellent performance in mixing air and a fuel and stabilizing a flame, having less pressure drop, and is easy to be manufactured and maintained. 
     Technical Solution 
     According to an aspect of the inventive concept, there is provided a swirler including a casing, a pilot body disposed in the casing, and a plurality of vanes arranged along a circumference of the pilot body, wherein at least a part of the vane protrudes further to a downstream than an end portion of the pilot body. 
     Advantageous Effects 
     According to an aspect of the inventive concept, a swirler has excellent performance in mixing air with a fuel and stabilizing a flame, less pressure drop, and is easy to be manufactured and maintained. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a partially cut perspective view of an axial flow swirler according to prior art; 
         FIG. 2  is a schematic cross-sectional view showing a side of the axial flow swirler of  FIG. 1  based on a symmetric axis; 
         FIG. 3  is a schematic cross-sectional view showing a side of a radial flow swirler according to prior art, based on a symmetric axis; 
         FIG. 4  is a partially cut perspective view schematically showing a swirler according to an embodiment of the inventive concept; 
         FIG. 5  is a partially cross-sectional view schematically showing an internal structure of the swirler of  FIG. 4 ; 
         FIG. 6  is a schematic diagram showing a coupling shape of vanes to a pilot body in the swirler of  FIG. 4 , as seen from a front portion of the pilot body; 
         FIG. 7  is a schematic diagram showing a coupling shape of the vanes to the pilot body in the swirler of  FIG. 4 , as seen from a side of the pilot body; 
         FIG. 8  is a schematic diagram partially showing the inside of the swirler of  FIG. 4 ; 
         FIG. 9  is a schematic diagram showing an inlet side of the swirler of  FIG. 4 ; 
         FIG. 10  is a schematic diagram showing a flow path formed inside the swirler of  FIG. 4 ; 
         FIG. 11  is a schematic diagram showing the inside of the swirler of  FIG. 4 , for illustrating a shape of one vane; and 
         FIG. 12  is a schematic diagram showing a flow of fluid at an outlet portion of the swirler of  FIG. 4 . 
     
    
    
     BEST MODE 
     According to an aspect of the inventive concept, there is provided a swirler including a casing, a pilot body disposed in the casing, and a plurality of vanes arranged along a circumference of the pilot body, wherein at least a part of the vane protrudes further to a downstream than an end portion of the pilot body. 
     The casing may comprise an inlet portion and an outlet portion, and an expansion portion having an increasing inner diameter between the inlet portion and the outlet portion. 
     The vane may comprise an inclined portion that is inclined with respect to a lengthwise direction of the pilot body, and the inclined portion may be disposed inside the expansion portion. 
     When an angle between a corner of the vane adjacent to the casing and a radial direction of a center axis of the swirler is α, an inclination of the vane with respect to the center axis direction of the swirler is β, and when an angle between the center axis direction of the swirler and a corner of the vane adjacent to the outlet portion of the swirler is θ, the angles α, β, and θ may satisfy following conditions, 0°&lt;α&lt;90°, 30°&lt;β&lt;60°, 30°&lt;θ&lt;60°. 
     The swirler may further comprise a plurality of atomizers coupled to the casing for atomizing a fuel of a liquid phase into flow paths between the plurality of vanes. 
     The swirler may further comprise a plurality of gas inlets disposed on the inlet portion of the casing for spraying a fuel of a gas phase into the flow paths between the plurality of vanes. 
     MODE OF THE INVENTIVE CONCEPT 
     A swirler will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the inventive concept are shown. In the accompanying drawings, sizes of components may be exaggerated, omitted, or reduced for convenience of explanation. In addition, like reference numerals in the drawings denote like elements, and thus their description may be omitted. 
       FIG. 4  is a partially cut perspective view of a swirler according to an embodiment of the inventive concept, and  FIG. 5  is a partially cross-sectional view schematically showing an internal structure of the swirler of  FIG. 4 . 
     Referring to  FIGS. 4 and 5 , a swirler  100  according to the embodiment includes a casing  110 , a pilot body  150 , a plurality of vanes  120 , atomizers  160 , and gas inlets  170 . 
     The casing  110  partitions an internal space and is in communication with a burner (not shown). The casing  110  includes an inlet through which the air is introduced and an outlet through which the air is discharged. The air introduced through the inlet changes its flow direction while passing through the vanes  120  that are fixedly arranged in the casing  110 , and then, is discharged after passing through a pre-chamber  51  to be introduced into the burner that is connected to a downstream side of the swirler  100 . 
     The pilot body  150  ignites an air/fuel mixture gas and stabilizes a flame sufficiently, and extends in direction of a center axis of the swirler  100  in an internal space of the casing  110 . A pilot atomizing device  152 , a gas pilot  154 , and an igniter  156  are disposed at an end portion of the pilot body  150  adjacent to the burner. The pilot atomizing device  152  atomizes a fuel of a liquid phase into a combustion chamber of the burner, and the gas pilot  154  atomizes a fuel of a gas phase into the combustion chamber of the burner. As such, by atomizing the fuel of the liquid phase or the fuel of the gas phase into the combustion chamber by using the pilot atomizing device  152  and the gas pilot  154 , the flame in the burner may be maintained effectively. The gas pilot  154  may include a plurality of gas outlet holes, some of which may be formed in a flat end portion of the pilot body  150  and some other of which may be along a periphery of the pilot body  150  at constant intervals therebetween. The number and a location of the gas pilot  154  are not limited thereto, but may be modified variously. The igniter  156  performs ignition so that a combustion reaction of the air/fuel mixture gas may occur. An end portion of the pilot body  150  toward the burner may be inclined. 
     The vanes  120  are arranged along a periphery of the pilot body  150  with constant intervals and inclined with respect to a direction of introducing the air GA so as to change the flow direction of the air GA. 
       FIGS. 6 and 7  are schematic diagrams showing one vane  120  coupled to the pilot body  150  in order to describe a shape of coupling the vanes  120  to the pilot body  150 , as respectively seen from a front portion and a side portion of the pilot body  150 . 
     Referring to  FIGS. 6 and 7 , the pilot body  150  includes a cylinder portion  151 , and an inclined end portion  153  at an end portion of the cylinder portion  151  and to be inclined. Also, the vane  120  includes a base portion  122  coupled to the cylinder portion  151  of the pilot body  150  and extending in a lengthwise direction of the pilot body  150 , and an inclined portion  124  extending from the base portion  122  and inclined with respect to the lengthwise direction of the pilot body  150 , that is, a center axis of the swirler, at an angle of β. The inclined portion  124  is coupled to the inclined end portion  153  of the pilot body  150 . In addition, referring to  FIG. 6 , a contact point LT between the inclined portion  124  of the vane  120  and the pilot body  150  is located on a tangent to a virtual pilot body  159  of a cylindrical shape located inside the pilot body  150 . The other vanes  120  are also coupled to the pilot body  150  in the same manner as above. The inclined portion  124  of the vane  120  protrudes from the pilot body  150  toward a pre-chamber  51 . Therefore, spaces  104  are defined between inclined portions of the plurality of vanes. 
     Each of the atomizers  160  is a device for atomizing the fuel of the liquid phase in the form of fine droplets to the introduced air GA in order to mix the air GA introduced into the swirler  100  with the fuel of the liquid phase.  FIG. 8  is a diagram showing the swirler  100  according to the embodiment seen from a fluid outlet side, and the casing  110  is divided into halves so that the arrangement of the atomizers  160  may be clearly shown. Referring to  FIG. 8 , the atomizers  160  are arranged along an external periphery of the casing  110  at constant intervals, and between the vanes so as to atomize the fuel to the flow paths between the vanes  120 . Also, the atomizers  160  may not be perpendicular to an external side surface of the casing  110 , but may be inclined with respect to the external side surface of the casing  110 . 
     The gas inlet  170  is provided to mix the air introduced into the swirler  100  and the fuel of a gas phase.  FIG. 9  schematically shows that the gas inlet  170  is disposed at an air inlet side of the swirler  100  of the embodiment. The gas inlet  170  is between every two vanes  120 , and injects a fuel gas to the flow paths formed between the vanes  120 . The gas inlet  170  may include a plurality of gas injection nozzles (not shown in  FIG. 9 ) at the side of the vanes  120  in order to inject the fuel gas. One or more gas inlets  170  may be disposed between every two vanes  120 . And the gas inlet  170  may be installed to overlap the vane  120  or the gas inlet  170  may be installed at the vane  120  directly. 
     Next, an internal structure of the swirler  100  according to the embodiment will be described in detail below.  FIG. 10  omits some of the vanes  120  so as to clearly show the flow path of the introduced air GA in the casing  110 , and  FIG. 11  selectively shows one vane  120  so as to clearly show the shape of the vane  120 . 
     Referring to  FIGS. 10 and 11 , the casing  110  of the swirler  100  includes an inlet portion  112 , through which the air is introduced, an outlet portion  114 , and an expansion portion  113  protruding outwardly while an inner diameter thereof increases between the inlet portion  112  and the outlet portion  114 . 
     The expansion portion  113  includes a first inclined portion  1131  extending from the inlet portion  112  while being slanted, a flat portion  1132  cylindrically formed from the first inclined portion  1131  without an inclination, and a second inclined portion  1133  extending from the flat portion  1132  and being inclined while the inner diameter thereof reduces. The outlet portion  114  is connected to the second inclined portion  1133 , and the inner diameter of the outlet portion  114  may increase or be constant toward a downstream. 
     The first inclined portion  1131  extends from around a point, where the inclined end portion  153  of the pilot body  150  starts, to around a point, where the inclined end portion  153  of the pilot body  150  ends. The vane  120  is mainly disposed in an internal space of the first inclined portion  1131  so as to occupy the internal space of the first inclined portion  1131 , and reduces an effective cross-sectional area of the flow path. Thus, the internal space of the first inclined portion  1131  is expanded, compared to that of the inlet portion  112 . Therefore, the effective cross-sectional area of the flow path from the inlet portion  112  to the first inclined portion  1131  may be maintained similarly. That is, the cross-sectional area of the flow path denoted by A in  FIG. 10  may have a substantially similar area to that of the flow path denoted by B in  FIG. 10 . Also, when it is assumed that the cross-sectional area of the flow path formed over the first inclined portion  1131  is B, A and B may be substantially similar to each other. In addition, an outlet of the swirler or the portion denoted by A corresponds to limits of flashback due to a safety issue. 
     The flat portion  1132  and the second inclined portion  1133  are successively formed next to the first inclined portion  1131 . The flat portion  1132  may provide a space where the atomizers  160  are formed. The atomizers  160  atomize the fuel of the liquid phase to make the introducing air GA and the fuel mixed together. 
     The second inclined portion  1133  extends to a location corresponding to an end of the vane  120 , and the flow path inside the second inclined portion  1133  is formed so as to gradually reduce the cross-sectional area thereof. That is, a portion denoted by C in  FIG. 10  is formed inside the second inclined portion  1133 . As such, the cross-sectional area of the flow path is reduced at the C portion, and the air/fuel mixture gas escaping from the vane  120  may be accelerated. 
     As shown in  FIGS. 10 and 11 , when it is assumed that an angle between a corner  1241  of the vane  120 , which is adjacent to the casing  110 , and a radial direction of the center axis of the swirler is α, an inclination of the vane  120  with respect to the center axis of the swirler  100  is β, and an angle between a direction of the center axis SC of the swirler  100  and a corner  1242  of the vane  120 , which is adjacent to the outlet of the swirler  100 , is θ, α, β, and θ satisfy following conditions. 
     0°&lt;α&lt;90°, 30°&lt;β&lt;60°, 30°&lt;θ&lt;60° 
     In more detail, α may be set as about 30°, β may be set as about 45°, and θ may be set as about 45°. Desirable ranges of α, β, and θ may vary within a range of 10°. 
     According to the casing  110  and the vanes  120  designed as described above, the fluid passing through the vanes  120  ends up to have a flow velocity in a radial direction due to the portion C shown in  FIG. 10 , and the inclination angles of the vanes  120 , that is, α and θ, and accordingly, the fluid moves similarly to the flow passing through a radial flow swirler. That is, the fluid that has passed through the vanes  120  ends up to have the velocity in the radial direction as well, and thus, a mixing characteristic is improved. 
     Also, due to the C region having the reduced cross-sectional area, velocity of the fluid escaping varies from a downstream side end d of the vanes  120  to the end e of the vanes  120  adjacent to the pilot body  150 , and thereby causing generation of a whirlpool and further accelerating the mixture of the air and the fuel. Therefore, the air GA introduced into the swirler  100  and the fuel GF atomized from the atomizers may be effectively mixed with each other, and stability of the flame in the chamber of the burner may be improved. 
     In addition, a swirler exit area of the swirler  100  can be controllable by an inclination angle of the vane  120 , that is, the angles β and θ shown in  FIGS. 10 and 11 , and a thickness of the vane  120 . The swirler exit area of the swirler  100  can be also controllable by a diameter of the pre-chamber, and a diameter of the virtual pilot body  159  shown in  FIG. 6  or the pilot body  150 . 
       FIG. 12  schematically shows a fluid outlet of the swirler  100 , and shows a flow path of the air/fuel mixture gas GM that has passed through the vanes  120 . As shown in  FIG. 12 , the fluid, that is, the air/fuel mixture gas GM, that has passed through the vanes  120  changes its flow path toward the center portion of the swirler  100 , that is, toward the pilot body  150 . Therefore, a vortex in the axial direction generated due to the escaping angle of the air/fuel mixture gas and the region C of  FIG. 10  is introduced into the burner while showing a flow similar to a vortex generated due to the radial flow swirler, due to the inclination angle β of the vanes  120 . That is, the swirler according to the embodiment has a similar shape to that of the axial flow swirler so that the flow of the air/fuel mixture gas may be easily controlled and the swirler may be simply manufactured, and at the same time, the swirler may generate a large variation in the flow velocity so as to effectively improve the performance of mixing the air with the fuel like a radial flow swirler. 
     When a velocity of the fluid in the axial direction was simulated while varying the internal structure of the swirler  100  according to the embodiment, the velocity and recirculation of the fluid become weak when the inclination angle of the vanes  120  is small. On the other hand, when the inclination angle of the vanes  120  increases, the recirculation region of the fluid is strongly generated, but the recirculation region is far from the pilot body  150 . Thus, for example, when the inclination angle θ of the vanes  120  is set as 45° and the inclination angle β is set as 45° appropriately, the recirculation and the velocity of the fluid are very excellent. 
     In addition, when an equivalence ratio was simulated while varying the internal structure of the swirler  100  according to the embodiment, the mixing characteristic degraded when the escaping angle of the fluid is small. In addition, when the inclination angles of the vanes  120  are large, an excellent mixing characteristic is shown around the pilot body  150 , but a cavity area CV may be formed at the center portion of the burner. For example, when the inclination angle θ of the vane  120  is set as 45° and the inclination angle β of the vane  120  is set as 45° appropriately, the mixture of the air and the fuel may be performed sufficiently. As described above, according to the embodiment, when the inclination angle θ is 45° and the inclination angle β is 45°, the swirler  100  generates the strong recirculation region, the velocity of the fluid is appropriate, and the excellent performance of mixing the air and the fuel is shown, according to the above numerical analysis. 
     The inventor of the application applied the swirler  100  of the embodiment to a different size of burner to perform computational fluid analysis. Conditions of analyzing the numerical values are shown in table below. 
     
       
         
           
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
             
            
               
                 Output (MWe) 
                 10 MWe 
                 220 MWe 
               
               
                 Thermal output (MWt) 
                 26.5 MWt  
                 579 MWt     
               
               
                 The number of cans 
                 6 
                 16 
               
               
                 Pressure (atm) 
                 15 
                 20 
               
               
                 Input temperature of 
                 660 
                 700 
               
               
                 swirler (K) 
               
               
                 Flux of compressed 
                 28 
                 645 
               
               
                 air (kg/s) 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 Target/ 
                 Numerical 
                 Target/ 
                 Numerical 
               
               
                   
                 expected 
                 analysis 
                 expected 
                 analysis 
               
               
                   
                 value 
                 result 
                 value 
                 result 
               
               
                   
               
               
                 Turbine introduction 
                 1450 
                 1434 
                 1450 
                 1432 
               
               
                 temperature (K) 
               
               
                 NO x @ 15% O 2 -Dry 
                 8 
                 7 
                 10 
                 18.3 
               
               
                 (ppmv) 
               
               
                   
               
            
           
         
       
     
     As shown in the table above, when the swirler according to the embodiment is applied to the burner, the swirler may exhibit excellent performance in cases of both a low output burner and a high output burner. 
     That is, according to results of simulating an axial velocity, an equivalence ratio, a temperature, a distribution of NOx-dry, and a temperature path line when the swirler according to the embodiment is manufactured to a size of 10 MWe, the swirler according to the embodiment applied to the burner exhibited excellent performances in various fields. 
     In addition, according to results of simulating an axial velocity, an equivalence ratio, a temperature, distribution of NOx-dry, and a temperature path line when the swirler  100  according to the embodiment was manufactured to be suitable for a high output burner, e.g., a burner of 220 MWe, the swirler according to the embodiment exhibited excellent performances in various fields even when being applied to a high output burner. 
     Although the swirler according to the embodiment is described as above, one or more embodiments are not limited thereto, and the inventive concept may be implemented variously. 
     For example, in the above embodiment, the atomizers  160  and the gas inlets  170  are provided to use the fuel of the liquid phase and the fuel of a gas phase together, but only one of the fuels of the liquid phase and the gas phase may be used. 
     In addition, the atomizers and the gas inlets are provided on the pilot body  150  for maintaining the flame, but one of the atomizers and the gas inlets may not be provided on the pilot body. 
     Also, in the above embodiment, the casing  110  includes the expansion portion  113 , but the casing  110  may not include the expansion portion. In this case, the casing  110  may be formed to have a cylindrical shape overall. 
     In addition, in the above embodiment, each vane  120  includes the base portion  121  and the inclined portion  123 , but the vane may only include the inclined portion, without including the base portion. 
     Additionally, the inventive concept may be implemented in various formats. 
     INDUSTRIAL APPLICABILITY 
     The inventive concept may be used in manufacturing and utilizing a swirler.