GB899359A - Improvements in or relating to forced-flow vapour generators - Google Patents

Abstract

899,359. Tube walls for furnaces. BABCOCK & WILCOX CO. Sept. 19, 1958 [Sept. 20, 1957], No. 30036/58. Class 51 (1). [Also in Group XIII] In a top-supported forced flow once through steam generator of the kind described in Specification 862,183 in order to ensure that the average temperature at any horizontal crosssection in each furnace wall is approximately the same, the wall tubes are horizontally divided into series connected double hairpin groups 44, 45, 46 which are connected between vertically-spaced horizontal headers common to all wall groups. The lower return bends of the groups 45, 46 are connected to enthalpy equalization headers 54, 57 which are located adjacent the junctures of the front and side walls of the generator and are connected between water drain collection and distribution headers 53, or 56 and 55 or 58 respectively. A downcomer 41 from an economizer 32 leads to a distribution header 43 for the first tube group 44 and an upflow tube 50B from the distribution header 43 of the group 46 is trifurcated for connection to three tubes 51 leading to a header 59. From the latter water passes through an enthalpy equalization header 60 in parallel paths through downcomers 61 to supply tubes 63 which lead to screen and baffle tubes 25, 64 respectively. Each generator wall includes metal webs 15 welded to adjacent tubes as shown in Fig. 5. In a modification, the upflow delivery tubes of one group are connected immediately to the collection header of the next group above it, return-bent tubes being interposed between extra drain headers and the corresponding distribution headers. In a further modification, the arrangement shown in Fig. 3 is modified in that the return-bent tubes in the same wall groups, e.g. tubes 48A, 48C in group 44, are adjacent each other instead of being spaced by the upflow tubes 48B.