Abstract:
A piping assembly for directing fluid and mitigating acoustic and vortex coupled resonance is provided that includes a main pipe delivering fluid in a first direction; a standpipe coupled to the main pipe at an intersection; and a scoop positioned at the intersection directing the fluid towards the standpipe. A scooping insert and a method for disrupting vortex shedding in a piping assembly are also provided.

Description:
The present invention relates generally to the reduction of high pressure oscillations associated with fluid flow past a standpipe and more specifically to a pipe assembly with a scoop for directing fluid traveling in a main pipe into a standpipe to mitigate acoustic and vortex coupled resonance. 
     BACKGROUND OF THE INVENTION 
     Power plants experience damage to relief valves and to fluid dryers caused by vortex shedding coupling with an acoustic mode in standpipes and other dead end piping branches. An acoustic side branch consisting of a large cantilevered “Helmholtz resonator” has been used on standpipes in some power plants to reduce vortex shedding. However, such a modification may be difficult and expensive. 
     U.S. Publication No. 2008/0149201 A1 discloses a main flow line and relief valve assembly that includes a main line fitted with a standpipe and a relief valve fitted within the standpipe. A sleeve is inserted in the standpipe below the relief valve to extend into the main line for mitigating acoustic cavity resonances. 
     SUMMARY OF THE INVENTION 
     The present invention may prevent acoustic resonance caused by the flow past an entrance to a standpipe. 
     A piping assembly for directing fluid and mitigating acoustic and vortex coupled resonance is provided that includes a main pipe delivering fluid in a first direction, a standpipe coupled to the main pipe at an intersection and a scoop positioned at the intersection directing the fluid towards the standpipe. 
     A scooping insert for directing fluid from a main pipe into a standpipe and mitigating acoustic and vortex coupled resonance at an entrance to the standpipe is also provided. The scooping insert includes a scoop having a first end for fluid to enter and a second end opposite the first end for fluid to exit. The first end is angled to direct fluid toward the second end. The scooping insert also includes a body portion coupled to the second end of the scoop and a coupling portion coupled to the body portion for attachment to a pipe. 
     A method for mitigating acoustic and vortex coupled resonance at an entrance to a standpipe is also provided. The method includes providing a scoop in an intersection between a main pipe and a standpipe to direct fluid flowing through the main pipe upward into the standpipe. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is described below by reference to the following drawings, in which: 
         FIG. 1  schematically shows a longitudinal cross-sectional view of a portion of a pipe assembly according to a preferred embodiment of the present invention; 
         FIG. 2  schematically shows a cut-away perspective view of a first longitudinal half of the pipe assembly shown in  FIG. 1 ; 
         FIG. 3  schematically shows a cut-away perspective view of a second longitudinal half of the pipe assembly shown in  FIGS. 1 and 2 ; 
         FIG. 4  schematically shows an upstream perspective view of the pipe assembly shown in  FIGS. 1 to 3 ; 
         FIG. 5  schematically shows a downstream perspective view of a scoop insert of the piping assembly shown in  FIGS. 1 to 4 ; 
         FIG. 6  schematically shows a side perspective view of the scoop insert shown in  FIG. 5 ; 
         FIG. 7  schematically shows an upstream perspective view a scoop insert according to another embodiment of the present invention. 
         FIG. 8  schematically shows a downstream perspective view of the scoop insert shown in  FIG. 7 ; and 
         FIG. 9  schematically shows a top view of the scoop insert shown in  FIGS. 7 and 8 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  schematically shows a longitudinal cross-sectional view of a portion of a pipe assembly  10  according to a preferred embodiment of the present invention.  FIGS. 2 ,  3  and  4  schematically show perspective views of pipe assembly  10 , with  FIGS. 2 and 3  showing cut-away perspective views of the two longitudinal halves of pipe assembly  10  and  FIG. 4  showing an upstream view of pipe assembly  10 . Pipe assembly  10  may transport fluids, such as steam flowing from a nuclear reactor. Pipe assembly  10  includes a main pipe  12 , a standpipe  14 , a relief valve  16  (omitted from  FIGS. 2 to 4  for clarity) and a scoop insert  18 . A first end  61  of standpipe  14  is coupled to main pipe  12  at an intersection  44  and a second end  62  of standpipe  14  is coupled to relief valve  16 . During normal operation, when a pressure in pipe assembly  10  is below a predetermined threshold of relief valve  16  and relief valve  16  is closed, steam in main pipe  12  flows from upstream of standpipe  14  to downstream of standpipe  14 . Scoop insert  18  is arranged to extend into main pipe  12  and drive a small portion of steam flowing through main pipe  12  upward into standpipe  14  to closed relief valve  16  and back into main pipe  12 . The upwardly directed steam then recirculates back into the main pipe  12 , thereby disrupting vortex shedding past the inlet of standpipe  14 . 
     Scoop insert  18  includes a coupling portion  20 , which may be flange  20 , a body portion  22 , which in this embodiment has semi-cylindrical shape, and a scoop  24 . Flange  20  may be fixed in between a flange  30  of standpipe  14  and a flange  32  of relief valve  16 . Body portion  22  extends downwardly from flange  20  against an inner circumference  41  of standpipe  14  and connects scoop  24  to flange  20 , which couples scoop  24  to second end  62  of standpipe  14 . Scoop  24  is positioned with a top end  34  of scoop  24  in standpipe  14  and a bottom end  36  of scoop  24  in main pipe  12 , so that scoop  24  is located at intersection  44  of standpipe  14  and main pipe  12  on an upstream side of standpipe  14  with respect to main pipe  12  and extends from within standpipe  14  into main pipe  12 . Scoop  24  may include a front face  26  extending downward from body portion  22  having an opening  40  formed therein. In this embodiment, front face  26  is integral and flush with body portion  22 . Scoop  24  also includes a channeling face  28  opposite of front face  26  extending from within standpipe  14  into main pipe  12 . Channeling face  28  is positioned to channel steam flowing through main pipe  12  into standpipe  14 . Channeling face  28  is substantially parallel with standpipe  14  at top end  34  and is angled with respect to standpipe  14  at bottom end  36 , so scoop  24  redirects steam flowing through main pipe  12  by approximately ninety degrees. In this embodiment, front face  26  has a semi-cylindrical shape and channeling face  28  has a semi-cylindrical shape at top end  34 . Thus, at top end  34 , front face  26  has a convex shape with respect to channeling face  28  and channeling face  28  has a concave shape with respect to front face  26 . Scoop  24  may also include channeling sides  27 ,  29  connecting front face  26  and channeling face  28  that assist in directing steam from main pipe  12  to standpipe  14 . In a preferred embodiment, standpipe  14  is six inches in diameter and main pipe  12  is twenty-four inches in diameter. 
     In alternative embodiment, flange  20  and body portion  22  may be omitted and scoop  24  may be directly coupled to at least one of main pipe  12  and standpipe  14 , for example by welding. 
       FIGS. 5 and 6  show a downstream perspective view and side perspective view, respectively, of scoop insert  18 . Flange  20  has evenly spaced holes  38  formed therein. Fasteners such as bolts may be passed through holes  38  to secure flange  20  to at least one of standpipe  14  ( FIGS. 1 to 4 ) or relief valve  16  ( FIG. 1 ). Front face  26  extends downward from body portion  22  and has opening  40  defined therein for steam to enter and be directed upwards by channeling face  28  towards body portion  22  and flange  20 . Channeling face  28  is parallel to body portion  22  at top end  34 , but extends downward and curves towards front face  26  at bottom end  36 . 
       FIGS. 7 and 8  show a perspective upstream view and a perspective downstream view of a scoop insert  118  according to another embodiment of the present invention. Scoop insert  118  may be inserted in standpipe  14  ( FIGS. 1 to 4 ) to direct steam from main pipe  12  ( FIGS. 1 to 4 ) into standpipe  14  in substantially the same manner as scoop insert  18  ( FIGS. 1 to 6 ). Scoop insert  118  includes a flange  120 , a body portion  122  and a scoop  124 . Scoop  124  includes a front face  126 , a channeling face  128  and channeling sides  127 ,  129 . Channeling sides  127 ,  129  connect front face  126  and channeling face  128  and assist in directing steam from main pipe  12  ( FIGS. 1 to 4 ) to standpipe  14  ( FIGS. 1 to 4 ). Body portion  122  extends downward from flange  120  to front face  126  at a top end  134  of scoop  124 , which curves away from body portion  122  at a bottom end  136  and protrudes past body portion  122  upstream in main pipe  12  ( FIGS. 1 to 4 ). At bottom end  136 , at least a portion of front face  126  may contact an inner circumference of main pipe  14  ( FIGS. 1 to 4 ). Channeling sides  127 ,  129  extend inwardly from front face  126 , connecting front face  126  with channeling face  128 . Front face  126 , channeling face  128  and channeling sides  127 ,  129  define an opening  140  for steam to flow through, which scoop  124  directs towards body portion  122  and flange  120 . At both ends  134 ,  136 , opening  140  has a semi-annular shape. 
       FIG. 9  shows a top view of scoop insert  118 . Top end  134  of scoop  124  is shown, with channeling sides  127 ,  129  extending radially inward from front face  126  towards channeling face  128 . Front face  126  has a convex shape with respect to channeling face  128  and channeling face  128  has a concave shape with respect to front face  126 . 
     In the preceding specification, the invention has been described with reference to specific exemplary embodiments and examples thereof It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of invention as set forth in the claims that follow. The specification and drawings are accordingly to be regarded in an illustrative manner rather than a restrictive sense.