GB1066972A - Improvements in and relating to steam generators - Google Patents

Abstract

1,066,972. Heating steam boilers by hot liquids. FOSTER WHEELER Ltd. June 19, 1964 [June 19, 1963; Jan. 16, 1964], Nos. 24423/63 and 2085/64. Heading F4A. In a once-through steam boiler heated by a liquefied metal, e.g; sodium, coolant of a nuclear reactor and comprising a vertical, cylindrical pressure vessel 10 containing an' open-topped vessel 12 with a sodium inlet 40 and outlet 44, the vessel 12 contains a number of vertical ducts 25 extending between plates 15, 22 and passing through an intermediate plate 14. Sodium leakage occurs where the ducts pass through plates 14, 22 to establish a small flow through space 46, the major flow being through the ducts, the sodium entering at 42 and leaving through their open lower ends. The vessel 10 is pressurized by an inert gas. Within each duct is housed a boiler unit consisting of a cluster of vertical tubes extending between headers 28, 30, each cluster comprising a central downcomer tube which connects a feedwater inlet 36 directly with the lower header 30 and a number of riser tubes which discharge steam into the upper header 28 whence it leaves the boiler through an outlet 38. Similar units may be used as economizers, superheaters and reheaters. With this arrangement the consequences of a tube failure are localized in the particular duct and tube replacement is facilitated, the faulty unit being lifted into a sealed flask, after sealing the inner container by plugs 18, removing the cover 47 and cutting the connections 36, 38. In a modification, Fig. 4 (not shown) the boiler unit connections 36, 38 are brought down through an axial duct and leave the vessel 10 through its bottom wall.