Method and apparatus for in situ inspection of reformer tubes

Abstract

A method and apparatus for accurately determining the interior profile of cylindrical objects such as reformer catalyst tubes is described. The radius of the tube is measured from the axis of the tube for each point of the interior surface by calculating the angle of a reflected light beam and the deviation thereof. A first embodiment reflects an light beam off of the interior surface of the cylinder and measures the angle of the light reflected from the interior of the cylinder. A second embodiment removes rotating parts by using a cone mirror to reflect a ring of light onto the interior of the cylinder. Signal processing means are provided to reduce surplus signals allowing transmission of only useful information.

1 . A device for inspecting the interior of metal tubes used in chemical processing for the presence of metal dusting and creep comprising a source of light adapted for focusing a spot of light on the interior surface of said tubes; means for focusing said light source on the interior surface of said reformer tube, and a detector for detecting said spot of light focused on the interior of said reformer tube, and means for centering said source and said detector in the center of said tube; and means for moving said detector, source, and centering means through said detector tube.  
   
   
       2 . A device for inspecting the interior of metal tubes used in chemical processing for the presence of metal dusting and creep as in  claim 1 , wherein said means for focusing said spot on the surface of said reformer tube includes a laser source and optical detector in a rotating head for rotating said spot around the inner circumference of said reformer tube.  
   
   
       3 . A device for inspecting the interior of metal tubes used in chemical processing for the presence of metal dusting and creep as in  claim 2  wherein said source is positioned forward of said detector in a direction away from the probe body and centering device.  
   
   
       4 . A device for inspecting the interior of metal tubes used in chemical processing for the presence of metal dusting and creep as in  claim 1 , wherein said centering device is adapted for use in reformer tubes by preventing chemical interaction with the inside surface of said reformer tube.  
   
   
       5 . A device for inspecting the interior of metal tubes used in chemical processing for the presence of metal dusting and creep as in  claim 4 , wherein said centering device is constructed so that all surfaces which may potentially contact the interior of said tube are constructed out of nonmetallic materials.  
   
   
       6 . A device for inspecting the interior of metal tubes used in chemical processing for the presence of metal dusting and creep as in  claim 1 , wherein said focusing means includes a conical mirror for projecting a focused ring of light on the interior surface of said reformer tube.  
   
   
       7 . A device for inspecting the interior of metal tubes used in chemical processing for the presence of metal dusting and creep as in  claim 6 , wherein said conical mirror is parabolic to focus said ring to a small circumferential line.  
   
   
       8 . A device for inspecting the interior of metal tubes used in chemical processing for the presence of metal dusting and creep as in  claim 6 , further comprising signal processing means to reduce the bandwidth of information transported out of said reformer tube.  
   
   
       9 . A method for forming a profile of the radius of the interior of a tubular structure comprising the steps of; producing a light beam on the axis of said tube, collimating said beam to focus on the surface of said tube, forming said collimated beam into a ring on the surface of said tube, projecting an image of said ring onto the surface of a sensor and moving said ring down the axis of said tube.  
   
   
       10 . A method for forming a profile of the radius of the interior of a tubular structure as in  claim 9 , further comprising the step of reflecting said beam off the surface of a conical mirror.  
   
   
       11 . A method for forming a profile of the radius the interior of a tubular structure as in  claim 9 , further comprising the step of reflecting said beam off the surface of a conical mirror with a parabolic surface for maintaining focus of said beam on the expected tube diameter.  
   
   
       12 . A method for forming a profile of the radius of the interior of a tubular structure as in  claim 9 , further comprising the steps of, reflecting said beam off a mirror at the axis of said tube, and rotating said mirror to produce a ring of light on the surface of said tube.  
   
   
       13 . A method for inspecting a reformer tube for chemical processing for damage including creep and metal dusting, comprising the steps of: 
 focusing a coherent light beam onto an interior of said tube and detecting at least a portion of a reflection of said light beam by converting the detected light beam into an electrical signal and processing said electrical signal to determine a radius of said tube.    
   
   
       14 . A method for inspecting a reformer tube for chemical processing for damage including creep and metal dusting according to  claim 13 , comprising the further step of rotating said light beam by reflecting at least a portion of said light beam it off a surface of a rotating mirror.  
   
   
       15 . A method for inspecting a reformer tube for chemical processing for damage including creep and metal dusting according to  claim 14 , wherein said detecting step is preformed by a charge coupled detector array.  
   
   
       16 . A method for inspecting a reformer tube for chemical processing for damage including creep and metal dusting according to  claim 14 , wherein a detector array is positioned aft of said light beam.  
   
   
       17 . A method for inspecting a reformer tube for chemical processing for damage including creep and metal dusting according to  claim 13 , comprising the step of reflecting said light beam off a conical mirror to focus said light beam into a ring on the interior surface of said tube.  
   
   
       18 . A method for inspecting a reformer tube for chemical processing for damage including creep and metal dusting according to  claim 17 , further comprising the step of processing said signal in said tube to at least one of filtering and enhancing collected data.  
   
   
       19 . A method for inspecting a reformer tube for chemical processing for damage including creep and metal dusting according to  claim 17 , wherein dynamic range is increased by the use of one or more parallel gain stages.  
   
   
       20 . A device for inspecting the interior of metal tubes used in chemical processing for the presence of metal dusting and creep according to  claim 1 , wherein the rotating portions of said device are adapted for high speed operation above 1500 revolutions per minute.  
   
   
       21 . A device for inspecting the interior of metal tubes used in chemical processing for the presence of metal dusting and creep according to  claim 20 , wherein said high speed operation is achieved by using a material that is substantially lighter than metal for the body of said device.  
   
   
       22 . A device for inspecting the interior of metal tubes used in chemical processing for the presence of metal dusting and creep according to  claim 21 , wherein said body is substantially smaller than the inside diameter of the tube sought to be inspected allowing inspection of several tube diameters.