U-Bend Tube Compression/Distortion Stabilization System (CDSS)

Abstract

This patent discloses and claims a system for providing in-plane stabilization to the tubes of a heat exchanger. The system increases the friction between the tubes and the existing anti-vibration bars by pressing the tube bundle together in the out-of-plane direction. The invention involves a structure that develops forces by reacting either off the inner diameter of the tube bundle wrapper, or off an assembled stressor hoop, which is self-supporting on top of the tube bundle, or involves purposely deforming connecting hoops to bias the anti-vibration bars in a way that the tube U-bend is no longer planar. It imposes a controlled clamping and/or deforming force on the tube bundle, either by direct contact with the outer tubes or indirectly via the existing anti-vibration bar structure.

What is claimed is: 
     
         1 . A system imparting in-plane stability to a heat exchanger having U-bend tubes with anti-vibration bars running therebetween, comprising:
 a plurality of load blocks positioned so as to be in contact with at least some of the anti-vibration bars;   a hoop coupled to each of said load blocks;   wherein said hoop is tensioned to provide an inwardly directed force to the U-bend tubes through the load blocks and anti-vibration bars.   
     
     
         2 . The system of  claim 1  wherein said hoop is tensioned so as to apply forces to said load blocks, said forces being balanced across opposite sides of the U-tubes and located to both compress and controllably deform the U-bend region such that controlled contact forces are generated between the anti-vibration bars and the U-bend tubes. 
     
     
         3 . The system of  claim 1 , wherein said hoop is tensioned so as to induce contact bets teen at least one of the U-bend tubes and an adjacent one of the anti-vibration bars. 
     
     
         4 . The system of  claim 3 , wherein said hoop is adjustably tensioned. 
     
     
         5 . The system of  claim 4 , wherein said hoop is designed to support a load of approximately 1000 to 9000 lbs. 
     
     
         6 . The system of  claim 1 , wherein at least one of said load blocks includes a body having a stepped profile such that each of said steps contacts a separate one of the anti-vibration bars. 
     
     
         7 . A method of providing in-plane stability to a heat exchanger having U-bend tubes with anti-vibration bars running therebetween, comprising:
 attaching a plurality of load blocks to the heat exchanger;   attaching a hoop to each of said load blocks; and   tensioning said hoop to provide an inwardly directed force to the U-bend tubes.   
     
     
         8 . The method of  claim 7 , wherein said attaching said plurality of load blocks to the heat exchanger includes attaching a least one of said plurality of load blocks to one of the anti-vibration bars. 
     
     
         9 . The method of  claim 7 , said tensioning includes tensioning said hoop such that at some of said U-bend tubes contact an adjacent anti-vibration bar. 
     
     
         10 . A method of providing in-plane stability to a heat exchanger having U-bend tubes arranged in bundles and having tube wrappers and further having anti-vibration bars running between the U-bend tubes, comprising:
 attaching a plurality of load blocks to the heat exchanger; and   attaching a restrictive foot to each of said load blocks, said restrictive foot positioned against the associated wrapper or other steam generator structure so as to compress its associated load block to provide an inwardly directed force to the U-bend tubes.   
     
     
         11 . The method of  claim 10 , wherein said attaching said plurality of load blocks to the heat exchanger includes attaching a least one of said plurality of load blocks to one of the anti-vibration bars. 
     
     
         12 . The method of  claim 10 , wherein said attaching a restrictive foot includes compressing said foot such that at least some of said U-bend tubes contact an adjacent anti-vibration bar. 
     
     
         13 . A method of providing in-plane stability to a heat exchanger having U-bend tubes with anti-vibration bars running therebetween, the anti-vibration bars being connected by a plurality of hoops, comprising plastically deforming at least one of the hoops such that at least some of said anti-vibration bars contact an adjacent U-bend tube. 
     
     
         14 . The method of  claim 13 , wherein said deforming includes making multiple deformations such that an inside portion of said at least one of the hoops is more displaced than outside portions of said at least one of the hoops, relative to a center of the heat exchanger. 
     
     
         15 . The method of  claim 14 , wherein said deforming includes making pairs of multiple deformations such that said at least one of the hoops has a stepped appearance, with each stepped portion of said at least one of the hoops being substantially parallel to the other stepped portions.