GB1339136A - Heat exchangers - Google Patents

Abstract

1339136 Liquid sodium heat exchangers UNITED KINGDOM ATOMIC ENERGY AUTHORITY 27 Aug 1971 [18 Sept 1970] 44621/70 Heading F4A In a heat exchanger wherein a heat transfer fluid such as liquid sodium is passed through a shell 1 so as to transfer heat to a fluid for example water/steam in U-shaped tubes 9, the tubes are arranged in bundles 8, each bundle being provided with inlet and outlet headers 4, 5 with tube plates 10, 11 to which the tubes are connected and being surrounded by a shroud 16 which provides a flowpath for sodium. The tubes of each bundle are located by transverse grids 41 interconnected by tie-bars 40 fixed to the grids 41 so as to allow for thermal expansion of the tubes 9. The grids each comprise a series of zig-zag members 45 attached by straight strips 46 to a plate 42. Tubular sleeves 40 extend between adjacent grids 41 to form the shroud 16, each sleeve 40 being welded to its respective upper grid 41 and being free to slide over a flange on the plate 42 of the respective lower grid 41 to accommodate thermal expansion of the tubes. Each shroud 16 is completed by a U-shaped sleeve 54 which has a duct 55 which leads to a space separated from the main part of the shell 1 by a baffle plate 33, the space being provided with an outlet 59 fitted with a bursting disc to provide pressure relief should a sodium/ . water reaction occur in any of the shrouds. Hot liquid sodium enters the heat exchanger at the bottom and passes up through an inlet manifold 15, 32 to a header 20 which feeds liquid sodium to each shroud at the outlet end of the tubes 9. The sodium flows through the shrouds to the inlet ends of the tubes 9 and then enters the shell 1 and finally exits through outlets 61. A by-pass arrangement may be provided to ensure circulation through the shell. The top part of the shell 3 including the inlet and outlet headers 4, 5, the tube bundles 8, the shrouds 16, the sodium inlet manifold 15 and header 20 are all supported on a strong back plate 12 so that they may be removed from the shell for servicing. Insulation is provided in the shrouds 16, the inlet manifold 15 and header 20 and in thermal sleeves 29. Bellows are provided in the thermal sleeves 29 and the ducts 55 to permit expansion of the tubes 9. In another embodiment, Fig. 9, not shown, the tube bundles extend through a lower tube plate to an upper tube plate in each head, the tube plates enclosing a space filled with argon which is monitored to detect leakage of sodium or water. Inspection covers are provided surrounding each space and at the tops of the headers to give access to the tube plates.