ES340101A1 - Heat exchanger - Google Patents

Abstract

A heat exchanger for a nuclear power plant steam generator and superheater comprises outer tubes 7 for circulation of liquid sodium and inner tubes 8, Fig. 5, for water, the outer tubes each comprising straight portions joined by bends to form a double "S", as shown, and connected at each end to headers 10, 11 or 12, 13, and the inner tubes passing through the side walls of the outer tubes for connection to subheaders 18, 20 or 21 and headers 19, 22. The arrangement shown comprises an economizer and evaporator unit 1 and a superheater unit 3. Liquid sodium, constituting the secondary coolant of a fast reactor, enters header 13 of superheater 3 and passes through a loop between outlet header 12 and inlet header 11 of unit 1, and finally leaves cold header 10. Water enters at header 19 and passes as steam through subheader 20 into superheater 3, superheated steam leaving via sub-header 21 and header 22. Each unit 1 and 3 comprises a series of outer tubes 7 arranged side-by-side, Fig. 2 (not shown) with their ends connected alternately along the opposite sides of the headers. The assembly is suspended by tie-rods in a heatinsulated enclosure 5. The inner tubes are supported in the outer tubes by a framework brace, Fig. 3 (not shown), or by an assembly of "hairpin" spacers, Fig. 4 (not shown). Leaking inner tubes can be isolated at their connections to the sub-headers, and faulty outer and inner tube assemblies can be removed easily due to their staggered arrangement, isolating valves being provided.