Tube arrangement in a once-through horizontal evaporator

Abstract

Disclosed herein is a once-through evaporator comprising an inlet manifold; one or more inlet headers in fluid communication with the inlet manifold; one or more tube stacks, where each tube stack comprises one or more inclined evaporator tubes; the one or more tube stacks being in fluid communication with the one or more inlet headers; where the inclined tubes are inclined at an angle of less than 90 degrees or greater than 90 degrees to a vertical; where each tube stack comprises a plurality of tubes arranged in a plurality of columns and a plurality of rows; where a plurality of tubes in a first column are offset from a plurality of tubes in a second column by a distance d2 and where a plurality of tubes in a first row are offset from a plurality of tubes in a second row by a distance d1; where d1 varies from 0.1d2 to 1000d2; one or more outlet headers in fluid communication with one or more tube stacks; and an outlet manifold in fluid communication with the one or more outlet headers.

What is claimed is: 
     
         1 . A once-through evaporator comprising:
 an inlet manifold;   one or more inlet headers in fluid communication with the inlet manifold;   one or more tube stacks, where each tube stack comprises one or more inclined evaporator tubes; the one or more tube stacks being in fluid communication with the one or more inlet headers; where the inclined tubes are inclined at an angle of less than 90 degrees or greater than 90 degrees to a vertical; where each tube stack comprises a plurality of tubes arranged in a plurality of columns and a plurality of rows; where a plurality of tubes in a first column are offset from a plurality of tubes in a second column by a distance d2 and where a plurality of tubes in a first row are offset from a plurality of tubes in a second row by a distance d1; where d1 varies from 0.1d2 to 1000d2   one or more outlet headers in fluid communication with one or more tube stacks; and   an outlet manifold in fluid communication with the one or more outlet headers.   
     
     
         2 . The once-through evaporator of  claim 1 , where the distances d1 and d2 are average distances. 
     
     
         3 . The once through evaporator of  claim 1 , where the distance between successive columns can be varied. 
     
     
         4 . The once through evaporator of  claim 1 , where the distance between successive rows can be varied. 
     
     
         5 . The once through evaporator of  claim 1 , where the distance between the one or more tube stacks can be varied. 
     
     
         6 . The once-through evaporator of  claim 1 , where the tube stack comprises a tube that is substantially horizontal in a direction that is perpendicular to a direction of flow of hot gases and inclined in a direction that is parallel to the direction of flow of the hot gases. 
     
     
         7 . The once-through evaporator of  claim 1 , where the tubes in the tube stack are in a staggered arrangement; where the tubes in one row are off set from the tubes in a preceding or succeeding row. 
     
     
         8 . The once-through evaporator of  claim 1 , where the tubes in the tube stack are in a staggered arrangement, where the tubes in one row lie directly above the tubes in a succeeding row and directly below the tubes in a preceding row. 
     
     
         9 . The once-through evaporator of  claim 1 , further comprising an unoccupied space that is produced by a difference in a geometry of an inclined evaporator tube stack and a horizontal evaporator tube stack. 
     
     
         10 . The once-through evaporator of  claim 9 , wherein the unoccupied space is filled with a partial tube stack. 
     
     
         11 . The once-through evaporator of  claim 9 , where the unoccupied space contains control equipment for regulating flow of the working fluid through the tubes. 
     
     
         12 . The once-through evaporator of  claim 1 , further comprising a baffle disposed between tube stacks. 
     
     
         13 . The once-through evaporator of  claim 1 , where a tube stack straddles a baffle. 
     
     
         14 . The once-through evaporator of  claim 1 , where the tube stack comprises a tube that is substantially horizontal in a direction that is parallel to a direction of flow of hot gases and inclined in a direction that is perpendicular to the direction of flow of the hot gases. 
     
     
         15 . The once-through evaporator of  claim 1 , where the tubes in the tube stack are in an inline arrangement, where the tubes in one row lie directly above the tubes in a succeeding row and directly below the tubes in a preceding row. 
     
     
         16 . A method comprising:
 discharging a working fluid through a once-through evaporator; where the once-through evaporator comprises:   an inlet manifold;   one or more inlet headers in fluid communication with the inlet manifold;   one or more tube stacks, where each tube stack comprises one or more inclined evaporator tubes; the one or more tube stacks being in fluid communication with the one or more inlet headers; where the inclined tubes are inclined at an angle of less than 90 degrees or greater than 90 degrees to a vertical; where each tube stack comprises a plurality of tubes arranged in a plurality of columns and a plurality of rows; where a plurality of tubes in a first column are offset from a plurality of tubes in a second column by a distance d2 and where a plurality of tubes in a first row are offset from a plurality of tubes in a second row by a distance d1; where d1 varies from 0.1d2 to 1000d2;   one or more outlet headers in fluid communication with one or more tube stacks; and   an outlet manifold in fluid communication with the one or more outlet headers;   discharging a hot gas from a furnace or boiler through the once-through evaporator; and   transferring heat from the hot gas to the working fluid.