Abstract:
A micromixer assembly of a turbine system includes a plate having at least one aperture comprising a receiving diameter. Also included is at least one tube having an inlet and an outlet for receiving a flow and dispersing the flow to a combustor, wherein the at least one tube includes an inner diameter and an outer diameter, wherein the outer diameter is configured to fit within the receiving diameter of the at least one aperture, wherein the at least one tube is operably coupled at a location on the outer diameter to the receiving diameter of the at least one aperture by exerting a radial force on the inner diameter of the tube.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The subject matter disclosed herein relates to turbine systems, and more particularly to micromixer assemblies of turbine systems. 
         [0002]    Turbine systems often include a micromixer assembly that typically includes a plurality of pipes or tubes that are disposed within apertures of a micromixer plate. The number of pipes or tubes is commonly well in excess of 10,000, and therefore assembly of the pipes or tubes within each micromixer plate aperture is cumbersome. A common method of assembling the pipes or tubes within the apertures involves a brazing process which relies on relatively expensive brazing filler, which may include gold and/or nickel. Such a process is both time consuming and expensive. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0003]    According to one aspect of the invention, a micromixer assembly of a turbine system includes a plate having at least one aperture comprising a receiving diameter. Also included is at least one tube having an inlet and an outlet for receiving a flow and dispersing the flow to a combustor, wherein the at least one tube includes an inner diameter and an outer diameter, wherein the outer diameter is configured to fit within the receiving diameter of the at least one aperture, wherein the at least one tube is operably coupled at a location on the outer diameter to the receiving diameter of the at least one aperture by exerting a radial force on the inner diameter of the tube. 
         [0004]    According to another aspect of the invention, a micromixer assembly of a turbine system includes a plate having a plurality of apertures. Also included is a plurality of tubes, each having an inner diameter and an outer diameter, wherein the outer diameter is configured to fit within the plurality of apertures. Further included is an expander configured to be removably disposed within the inner diameter, wherein the plurality of tubes are fixedly connected to the plurality of apertures by expansion of the expander. 
         [0005]    According to yet another aspect of the invention, a method of assembling a micromixer assembly of a turbine system is provided. The method includes inserting an expander having at least one expander head within an inner diameter of a tube. Also included is inserting the tube into a receiving aperture of a plate. Further included is exerting a radial force on the tube with the expander to form at least one operable connection between an outer diameter of the tube and the receiving aperture. 
         [0006]    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 
         [0007]    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: 
           [0008]      FIG. 1  is a perspective view of a turbine system having a micromixer assembly located in a head end; 
           [0009]      FIG. 2  is a top, cross-sectional view of a tube disposed within an aperture of a plate and an expander disposed within the tube; 
           [0010]      FIG. 3  is a flow diagram illustrating a method of assembling the micromixer assembly. 
       
    
    
       [0011]    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 
       [0012]    Referring to  FIG. 1 , illustrated is a turbine system  10  having a combustor section  12  and a head end  14 . The head end  14  is disposed at an adjacent upstream location of the combustor section  12  and includes a micromixer assembly  16 . The micromixer assembly  16  includes a plate  17  having a plurality of sectors  18  which each comprise a plurality of tubes  20 . The combustor section  12  is defined by an outer liner  22  that extends to an upstream end  24 . Spaced radially outwardly of the outer liner  22 , and surroundingly enclosing the outer liner  22 , is a flow sleeve  26 . A flow of air passes upstream within an air passage defined by the outer liner  22  and the flow sleeve  26  to the upstream end  24  of the outer liner  22 . 
         [0013]    Referring to  FIG. 2 , a top, cross-sectional view of a tube  20  of the plurality of tubes is illustrated within a receiving aperture  30  of the plate  17 . The plate  17  includes a plurality of receiving apertures that extend relatively axially through the plate  17  and are each configured to have a receiving diameter  32  that is dimensioned to allow the tube  20  to be inserted therein. Specifically, the tube  20  comprises an inner diameter  34 , an outer diameter  36 , an inlet  38  and an outlet  40 . It is the outer diameter  36  of the tube  20  that is dimensioned to be inserted within the receiving diameter  32  of the receiving aperture  30 . The tube  20  is typically formed of a durable material that is suitable for functioning in a region having a temperature that may exceed 1,600° F. (871° C.). Such a material may comprise stainless steel and/or a nickel-based alloy, such as Hastelloy® X. It is contemplated that a portion of a stainless steel tube may be formed of the Hastelloy® X material, such that only the non-stainless steel portion is disposed at the friction weld location, thereby providing a reliable portion of the tube  20  for enduring the aforementioned operation temperature. Similarly, the plate  17  comprises a material having high-temperature strength, such as stainless steel, for example. The aforementioned materials are discussed as merely illustrative examples and are not to be understood as limiting. 
         [0014]    The inner diameter  34  of the tube  20  is dimensioned to receive an expander  50  that includes at least one expander head  52 . Specifically, it is an outer diameter  54  of the expander head  52  that is to be closely dimensioned with that of the inner diameter  34  of the tube  20 . The expander  50  comprises a shaft portion  56  that extends in a longitudinal direction  58  that relatively coincides with an axial direction of the turbine system  10 , with the at least one expander head  52  disposed therealong. The function of the expander head  52  is to be controllably disposed at a position within the tube  20  that is desired to form a friction weld with the receiving aperture  30  of the plate  17 , the method of which will be described in detail below. It is to be appreciated that more than one friction weld may be desired for each tube  20 , and in such an application, the expander  50  includes a plurality of expander heads. This provides the ability to form a plurality of friction welds between each tube  20  and receiving aperture  30 . 
         [0015]    Referring to  FIG. 3 , a flow diagram generally illustrates a method of assembling  60  the micromixer assembly  16 . The method of assembling  60  comprises positioning the tube within the receiving aperture  62  and positioning the expander within the inner diameter of the tube  64 . The expander  50  is situated to have the expander head  52 , or the expander heads in the case of a plurality of friction welds as described above, disposed at a desired friction weld location. A rotor is operably connected to the tube and/or the expander shaft portion  68 . The rotor is then rotated 70 and 50 to a predetermined speed that is sufficient to result in a generation of heat through mechanical friction between the outer diameter  36  of the tube  20  and the stationary receiving aperture  30  of the plate  17 . The expander  50 , and particularly the expander head  52 , provides a radial force, known as an upset force, to displace and fuse the tube  20  to the receiving aperture  30 . 
         [0016]    It is to be appreciated that the expander  50  and the tube  20  may be rotated at speeds distinct from one another during the method of assembling  60 . This may be accomplished by employing a gear system, such as a planetary gear, where various gear ratios may be achieved by manipulation of the input gear of the planetary gear. In such an arrangement, the tube  20  may rotate at a first speed, which is different than that of a second speed that the expander  50  may rotate at. The precise speeds used will vary depending on the specific application, but as an example, the first speed may be about 1,000 rpm, while the second speed may be about 950 rpm. It is to be understood that the illustrative speeds described above are not limiting and that the ratio and speeds will vary accordingly. Operation at suitable speeds provide a relative rotational speed for the expander  50 , with respect to that of the tube  20  to generate an expanding effect, while avoiding excessive internal wall friction heat, which possibly leads to jointing the inner diameter  34  of the tube  20  to the expander  50 . Subsequent to the formation of the friction weld between the tube  20  and the receiving aperture  30 , the expander  50  is removed from the inner diameter  34  of the tube  20 . During the method of assembling  60 , the expander  50  and inner diameter  34  of the tube  20  are lubricated and liquid cooled. It is to be understood that the above description for the method of assembling  60  is not intended to limit the precise order of operations, such that the method of assembling  60  may include a different order of operations based on numerous assembly factors. 
         [0017]    Advantageously, the method of assembly  60  provides the capability to form each friction weld in a matter of seconds, thereby significantly reducing the time required to mechanically join the tube  20  and the receiving aperture  30  of the plate  17 , when compared to other processes employed to form such a mechanical joint, such as brazing, for example. Additionally, the method of assembling  60  employs direct heat input at the friction weld interface, yielding relatively small heat-affected zones. Such benefits are particularly useful in a high temperature operation region, such as that of the micromixer assembly  16 . The friction welding process also requires relatively brief preparation time, based on the tendency of the mechanical friction between the tube  20  and the receiving aperture  30  tending to clean the surface between the materials being welded. This is typically achieved when the aforementioned flash carries away dirt and debris that may have been present on a surface of the tube  20  and/or receiving aperture  30 . 
         [0018]    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.