Slotted impingement plates for heat exchangers

Abstract

Impingement plates for shell and tube heat exchangers are positioned between the inlet openings and the tubes with the surfaces of the impingement plates being normal to the flow path of the liquid entering the shell from the inlet openings and having a plurality of openings through which a portion of the liquid passes before contacting the tubes. The openings can be formed as elongated parallel slots that are positioned parallel to the tubes and function to enhance the fluid flow, especially in the area that is immediately downstream from the impingement plates, thereby reducing fluid stagnation, fouling and tube erosion and prolonging the useful life and time in service between maintenance shut downs.

1 . A shell and tube heat exchange apparatus for the transfer of heat from a first liquid to a second liquid comprising:
 a shell defining an interior space,   a plurality of spaced-apart tubes extending longitudinally in the shell, wherein the first liquid flows through the plurality of tubes,   an inlet opening for admitting the second liquid into the interior space in an inlet flow direction that is generally transverse to the tubes, and   an impingement plate positioned between the inlet opening and the tubes, the surface of the plate being normal to the flow path of the second liquid entering the shell from the inlet opening and having a plurality of openings through which a portion of the second liquid passes before contacting the tubes.   
     
     
         2 . The apparatus of  claim 1 , wherein the plurality of openings in the impingement plate are elongated slots. 
     
     
         3 . The apparatus of  claim 2 , wherein the slots extend along substantially the entire length of the plate. 
     
     
         4 . The apparatus of  claim 2 , wherein the slots are parallel to each other. 
     
     
         5 . The apparatus of  claim 2 , wherein the impingement plate is positioned so that the slots are parallel to the tubes. 
     
     
         6 . The apparatus of  claim 5 , wherein a portion of the slots are aligned with the spaces between the tubes. 
     
     
         7 . The apparatus of  claim 2 , wherein the width of each slot is about 6 mm and the space between the slots is about 25 mm. 
     
     
         8 . The apparatus of  claim 2 , wherein the length of each slot is about 136 mm. 
     
     
         9 . The apparatus of  claim 1 , wherein the impingement plate is rectilinear and generally planar. 
     
     
         10 . The apparatus of  claim 2 , wherein the slot openings constitute about 80% of the surface area of the impingement plate. 
     
     
         11 . The apparatus of  claim 2 , wherein the area of the impingement plate is about 110% of the area of the inlet opening. 
     
     
         12 . The apparatus of  claim 1 , wherein the shell and tube heat exchanger is a double split flow H-type further comprising:
 a second inlet for admitting a portion of the second liquid into the interior space in an inlet flow direction that is generally transverse to the tubes; and   a second impingement plate positioned between the second inlet and the tubes, the surface of the plate being normal to the flow path of liquid entering the shell from the second inlet, the second impingement plate having a plurality of openings through which a portion of the second liquid passes before contacting the tubes.   
     
     
         13 . A generally planar diffusing impingement plate configured and dimensioned for interpositioning between a liquid inlet opening in the exterior wall of a shell and tube heat exchanger and the tubes of the heat exchanger, the surface of the plate being generally planar and having a plurality of elongated spaced-apart slotted openings for diffusing and passing a portion of liquid contacting the surface of the plate. 
     
     
         14 . The plate of  claim 13 , wherein the plurality of openings in the impingement plate are elongated slots that extend from proximate opposing ends of the plate. 
     
     
         15 . A method of mitigating fouling on and corrosion of a portion of the tubes in a shell and tube heat exchanger that are in the flow path of a heat transfer liquid entering the heat exchanger through an inlet opening, the method including:
 providing a generally planar diffusing impingement plate having a plurality of elongated spaced-apart openings, and   positioning the plate proximate the liquid inlet opening to thereby diffuse and pass only a portion of the flowing liquid into direct contact with the tubes adjacent the plate.   
     
     
         16 . The method of  claim 15 , wherein the plurality of openings in the impingement plate are elongated slots and the slots are aligned parallel to the tubes.