Contact tray having tray supported downcomers and methods involving same

Abstract

A plurality of fluid-fluid contact trays of the cross-flow type are provided within a shell of a mass transfer or heat exchange column. The trays include tray decks that are supported on rings fixed to an inner surface of the shell and downcomers that are supported, not by the typical bolting bars fixed to the shell, but by the tray deck of the underlying tray. The mechanisms for supporting the downcomers in this fashion are support brackets that are not secured to the column shell, but instead extend downwardly from the downcomers and rest on the tray deck of the underlying tray. Alternating trays have side downcomers positioned at openings at one or both ends of the tray deck. The support rings on those trays having side downcomers may be truncated so that the rings do not extend around that portion of the shell circumference where the side downcomer openings are located. On the remaining trays, complete 360 degree rings may be used. Some or all of the downcomers have an inwardly extending shoulder segment in one or both side walls that supports portions of the tray deck and contains fluid passages.

Having thus described the invention, what is claimed is:  
     
         1 . A method of installing a plurality of contact trays within a mass transfer or heat exchange column comprising a shell defining an open internal region and having an inner surface with a preselected circumference, said method comprising the steps of: 
 providing a first tray support attached to said inner surface of the shell and extending in a first plane around some or substantially the entire circumference of the inner surface of the shell;    providing a second tray support attached to said inner surface of the shell and extending in a second plane spaced a preselected distance below the first plane around some or substantially the entire circumference of the inner surface of the shell;    providing a first tray and an underlying second tray, both said trays comprising a tray deck having vapor passages and opposed ends and opposed sides and a plurality of downcomers positioned at openings in the tray deck and extending downwardly for removing liquid when present on the tray deck; and    supporting said tray deck of the first tray on said first tray support and said tray deck of the second tray on said second tray support.    
     
     
         2 . The method of  claim 1 , including supporting the downcomers of said first tray on said second tray.  
     
     
         3 . The method of  claim 1 , including supporting the downcomers of said first tray on the tray deck of said second tray.  
     
     
         4 . The method of  claim 1 , including supporting the downcomers of said first tray entirely on said second tray.  
     
     
         5 . The method of  claim 1 , including the steps of supporting portions of the tray deck of the second tray on a horizontally extending beam having opposite ends supported on the second tray support and supporting the downcomers of said first tray at least partially with said beam.  
     
     
         6 . The method of  claim 1 , including positioning one of said openings at one end of said tray deck and providing a side downcomer at said one opening.  
     
     
         7 . The method of  claim 6 , including securing moveable support brackets at opposite ends of said side downcomer to support said side downcomer on the tray deck of the second tray, said moveable support brackets being free of attachment to the inner surface of said shell.  
     
     
         8 . The method of  claim 7 , including abutting said moveable support brackets against the inner surface of said shell.  
     
     
         9 . The method of  claim 1 , including constructing at least some of said downcomers with spaced apart side walls and end walls extending between the side walls to close opposite ends of the downcomer, each of said side walls comprises a lower segment, an upright intermediate segment and an inwardly extending shoulder segment, wherein at least one of said lower segments is inclined toward the other lower segment to from a lower discharge outlet having a preselected open area in a horizontal plane which is less than a horizontal cross-sectional area between said intermediate segments of the downcomer.  
     
     
         10 . The method of  claim 9 , including overlapping portions of said tray deck on said shoulder segments to provide support for said tray deck.  
     
     
         11 . The method of  claim 10 , including providing aligned openings in said shoulder segments and said overlapped portions of the tray deck.  
     
     
         12 . The method of  claim 11 , including providing weirs extending upwardly from inner edges of said shoulder segments.  
     
     
         13 . The method of  claim 12 , including forming at least one of the side walls in a one piece construction.  
     
     
         14 . A contact tray comprising: 
 a tray deck having vapor apertures for permitting vapor to ascend through the tray for mixing with liquid flowing across the tray deck;    an elongated opening in the tray;    a downcomer positioned at the opening for removing liquid from the tray deck when present thereon, said downcomer comprising spaced apart side walls and end walls extending between the side walls to close opposite ends of the downcomer, each of said side walls comprises a lower segment, an upright intermediate segment and an inwardly extending shoulder segment,    wherein at least one of said lower segments is inclined toward the other lower segment to from a lower discharge outlet having a preselected open area in a horizontal plane which is less than a horizontal cross-sectional area between said intermediate segments of the downcomer, and    wherein portions of said tray deck overlap and are supported on said shoulder segments; and    aligned fluid passage openings in said shoulder segments and said overlapped portions of the tray deck.    
     
     
         15 . The contact tray of  claim 14 , including weirs extending upwardly from inner edges of said shoulder segments.  
     
     
         16 . The contact tray of  claim 15 , wherein at least one of said side walls is of a one-piece construction.