Abstract:
An exhaust stack includes an inlet section extending along a first axis and an outlet section extending along a second axis. A co-axial silencer is arranged in one of the inlet section and outlet section. The co-axial silencer includes a plurality of concentric baffles configured and disposed to absorb acoustics generated by fluid flow through the exhaust stack.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The subject matter disclosed herein relates to the art of exhaust stacks and, more particularly, to an exhaust stack having a co-axial silencer. 
         [0002]    In general, exhaust stacks are fluidically connected to an internal combustion engine, a furnace or other system that produces exhaust gases. The exhaust stack delivers the exhaust gases from the system to ambient. In some cases, the exhaust stack includes filters that entrap particulate in the exhaust gases. The exhaust stack may be sized to affect a cooling of the exhaust gases prior to being expelled to ambient. In some cases, the exhaust stack includes a silencer that absorbs sounds produced by flowing exhaust gases. The silencer includes a plurality of sound absorbing baffles arranged in parallel along a flow path of the exhaust stack. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0003]    According to one aspect of an exemplary embodiment, an exhaust stack includes an inlet section extending along a first axis and an outlet section extending along a second axis. A co-axial silencer is arranged in one of the inlet section and outlet section. The co-axial silencer includes a plurality of concentric baffles configured and disposed to absorb acoustics generated by fluid flow through the exhaust stack. 
         [0004]    According to another aspect of an exemplary embodiment, a turbomachine includes a compressor portion and a turbine portion operatively connected to the compressor portion. The turbine portion includes an exhaust outlet. A combustor assembly includes at least one combustor fluidically connected to the compressor portion and the turbine portion. An exhaust stack is fluidically connected to the exhaust outlet of the turbine portion. The exhaust stack includes an inlet section extending along a first axis and an outlet section extending along a second axis. A co-axial silencer is arranged in one of the inlet section and outlet section. The co-axial silencer includes a plurality of concentric baffles configured and disposed to absorb acoustics generated by fluid flow through the exhaust stack. 
         [0005]    According to yet another aspect of an exemplary embodiment, a turbomachine includes a compressor portion, and a turbine portion operatively connected to the compressor portion. The turbine portion includes an exhaust outlet. A combustor assembly includes at least one combustor fluidically connected to the compressor portion and the turbine portion. A generator is operatively connected to the compressor portion. An exhaust stack is fluidically connected to the exhaust outlet of the turbine portion. The exhaust stack includes an inlet section extending along a first axis and an outlet section extending along a second axis. A co-axial silencer is arranged in one of the inlet section and outlet section. The co-axial silencer includes a plurality of concentric baffles configured and disposed to absorb acoustics generated by fluid flow through the exhaust stack. 
         [0006]    These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [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 schematic diagram of a turbomachine system including an exhaust stack having a co-axial silencer, in accordance with an exemplary embodiment; 
           [0009]      FIG. 2  is a perspective view of the exhaust stack of  FIG. 1 ; 
           [0010]      FIG. 3  is a perspective view of a co-axial silencer, in accordance with an aspect of the exemplary embodiment; 
           [0011]      FIG. 4  is a cross-sectional side view of the co-axial silencer of  FIG. 3 ; 
           [0012]      FIG. 5  is a cross-sectional side view of a co-axial silencer, in accordance with another aspect of an exemplary embodiment; and 
           [0013]      FIG. 6  is a perspective view of an exhaust stack having a co-axial silencer arranged in accordance with another aspect of an exemplary embodiment. 
       
    
    
       [0014]    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 
       [0015]    A turbomachine system, in accordance with an exemplary embodiment, is indicated generally at  2 , in  FIG. 1 . Turbomachine system  2  includes a turbomachine  3  having a compressor portion  4  operatively connected to a turbine portion  6  through a common compressor/turbine shaft  8 . Compressor portion  4  is also fluidically connected to turbine portion  6  through a combustor assembly  10  having one or more combustors  12 . Compressor portion  4  includes a compressor inlet  16  that is fluidically connected to an air intake system  18 . Compressor portion  4  may also be connected to a generator  20 . Of course, the particular connection of generator  20  to turbomachine  2  may vary. Turbine portion  6  includes a turbine portion outlet  22  that delivers exhaust gas to an exhaust stack  30 . 
         [0016]    As shown in  FIG. 2 , exhaust stack  30  includes a base section  35  having an inlet section  38  and an outlet section  40 . Inlet section  38  extends along a first axis  42 . Outlet section  40  extends along a second axis  44  that is generally perpendicular to first axis  42 . Inlet section  38  extends from a first end  48  to a second end  49  that is coupled to base section  35 . First end  48  includes an opening  50  that receives exhaust gas from turbine portion outlet  22 . Outlet section  40  extends from a first end  54  to a second end  55 . First end  54  of outlet section  40  is coupled to base section  35  and second end  55  is provided with an opening  56 . A transition section  60  is arranged between base section  35  and outlet section  40 . Transition section  60  provides an interface between a generally rectangular section (base section  35 ) and a generally tubular section (outlet section  40 ). In accordance with an exemplary embodiment, exhaust stack  30  includes a co-axial silencer  70  arranged along inlet section  38 . 
         [0017]    As shown in  FIGS. 3 and 4 , co-axial silencer  70  includes a plurality of concentric baffles  74  that are arranged about a central member  78 . Concentric baffles  74  are spaced one, from another, and from central member  78 , to form a plurality of generally annular flow passages, one of which is indicated at  80 . Central member  78  is formed from an acoustic attenuating material. Co-axial silencer  70  extends from a first end  83  to a second end  84 . First end  83  defines an inlet  85  and second end  84  defines an outlet  86 . In the exemplary embodiment shown, each concentric baffle  74  and central member  78  are generally circular and include a substantially constant cross-section. More specifically, a diameter of concentric baffles  74  is generally consistent between first and second ends  83  and  84 . 
         [0018]      FIG. 5  illustrates a co-axial silencer  90  in accordance with another aspect of the exemplary embodiment. Co-axial silencer  90  includes a plurality of concentric baffles  92  that are arranged about a central member  94 . Concentric baffles  92  are spaced one, from another, and from central member  94 , to form a plurality of generally annular flow passages, one of which is indicated at  96 . Co-axial silencer  90  extends from a first end  98  to a second end  99 . First end  98  defines an inlet  104  and second end  99  defines an outlet  105 . In the exemplary embodiment shown, each concentric baffle  92  and central member  94  taper outwardly from first end  98  to second end  99 . More specifically, a diameter of co-axial silencer  90  at first end  98  is less than a diameter at second end  99 . 
         [0019]    At this point it should be understood that the exemplary embodiments describe a co-axial silencer for an exhaust stack. A co-axial silencer, in accordance with the exemplary embodiments, leads to a lower pressure drop across an exhaust diffuser which provides enhanced turbomachine system performance. In addition to a lower pressure drop, the co-axial silencer has a smaller footprint while also providing an increase in effective sound attenuation surfaces by virtue of the concentric baffles. The reduced footprint enables an exhaust stack to have a shorter height without sacrificing performance. Further, it should be understood that while shown arranged at the inlet section, the co-axial silencer, in accordance with any of the embodiments, may be arranged along the outlet section, as shown in  FIG. 6 , wherein like reference numbers represent corresponding parts in the respective views. Also, while shown and described as being fluidically connected to a turbomachine system, the exhaust stack, with co-axial silencer, may be used in a wide range of systems spanning any number of technologies. Finally, while shown and described as being generally circular, the co-axial silencer may take on a variety of geometries including oblong, oval, elliptical, rectangular, and the like. 
         [0020]    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.