GB974355A - Improvements in and relating to header type tubular heat exchangers - Google Patents

Abstract

974,355. Tube-type heat exchangers. ENGLISH ELECTRIC CO. Ltd. March 24, 1961 [March 25, 1960; Sept. 8, 1960], Nos. 10653/60 and 30951/60. Heading F4S. In a header-type tubular heat exchanger including a vessel 1 having an inlet 3 for steam and an outlet 4 for condensate and a plurality of groups of heat exchange tubes 12 for feed water for a steam generator, each group of heat exchange tubes 12 has a separate inlet header 10 and a separate parallel outlet header 11. Each inlet header 10 is connected by a pipe 9 to a feed water inlet duct 7 and each outlet header 11 is connected by a pipe 9 to a feed water outlet duct 8. Each group comprises a row of tubes 12 extending up and down the vessel 1 twice between the corresponding inlet and outlet headers. The portions of the tubes 12 near the outlet headers 11 are encased in a mantle 13 closed at the bottom and into which the steam inlet 3 is connected. Each row of tubes 12 carries a number of baffle strips 40, the strips of one row fitting closely to the strips of the adjacent row. The baffle strips 40 combine with further strips and segmental plates to form transverse circular baffles, but some of the baffle strips 40 are omitted in each baffle to provide a zig-zag passage for the steam as indicated by the arrows. The further strips, vertical bars, a vertical plate 15 and ring segments form a frame supported from the inlet and outlet feed water duets 7, 8. The ring segments are bolted together and serve to trap the ends of the baffle strips 40. The tubes 12 can be removed for inspection by first withdrawing all the tubes, the headers and the frame from the vessel 1. Any group of tubes can then be removed sideways from the frame by removing the ring segments and cutting the connection pipes 9. In a modification, Fig. 5 (not shown), the inlet duct is connected by four fall pipes to inlet headers at the bottom of the casing and groups of heat exchange tubes lead upwardly, then horizontally, then upwardly to the top of the easing, then with two U-bends downwards and upwards to outlet headers at the top of the casing. The condensate outlet at the bottom of the casing is connected by a U pipe to a drain outlet box located above the level of the horizontal portions of the heat exchange tubes. In another modification, Figs. 6, 7 (not shown) the inlet duct is again connected by fall pipes to inlet headers at the bottom of the casing and short straight tubes lead therefrom to other headers extending across the whole width of the casing. Short branch pipes connect these headers to further parallel headers extending over one-third of the width of the casing. Long straight tubes then lead upwardly to headers at the top of the casing and then downwardly to further headers near the bottom of the casing and then upwardly to further headers at the top of the casing.