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878,232. Vertical steam boilers; steam separators. BABCOCK & WILCOX Ltd. Feb. 11, 1960 [Feb. 25, 1959], No. 6538/59. Classes 123(2) and 123(3) A steam generator especially suitable for use in marine power plants incorporating water-cooled nuclear reactors includes an upright cylindrical pressure vessel 1 containing in its lower part a bank 3 of upright tubes the end portions 3A, 3B of which are bent at right angles and connected to tube plates 5, 7 arranged respectively at the inner ends of inlet and outlet chambers 9, 11. In operation the heated water from the reactor entering the chamber 9 flows upwardly through the tubes and discharges through the chamber 11. The tube bank 3 is enclosed by a sheet metal jacket 13 around which is an annular space 15 through which water from the upper part of the drum together with feedwater introduced at 75 flows downwardly to a space 17 wherein it turns for upward flow over the tube bank. The upper end of the jacked 13 is connected by a sheet metal casing 121A to casing parts 121B, 121C mounted coaxially within the pressure vessel and forming a water and steam receiving space 123 in the upper portion thereof. The casing part 121C is closed at its upper end by a wall 122. Two tiers of centrifugal separators are arranged to receive the steam-water mixture from the space 123, each of the cylindrical casing parts 121B, 121C having peripherally spaced outlet ports 129 from which ducts lead into respective separators. The separators 151 of the lower tier are arranged to discharge water below the normal water level in the pressure vessel. The separators 131 of the upper tier discharge water downwardly into a trough 137 which completely encircles the casing part 121C, two drain tubes 143 acting as weirs to establish a water level in the trough above the bottoms of the separators 131. This arrangement of separators is also described and is claimed in Specification 878,231. Separated steam flows upwardly from the separators through corrugated plate scrubbers 153, 157 to an outlet pipe 159. In a modification the tube bank is formed of nested tubes of inverted U-shape, the upper chamber 11 being dispensed with whilst the lower chamber 9 is divided into an inlet and an outlet chamber receiving the ends of the U-tubes.
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