Patent GB-867306-A (GB)
Title: Improvements in vapour generating heat exchangers
Inventor: TAYLOR ANTHONY JAMES
IPC: F22B1/08
Filed: 1958-06-26
Abstract: 867,306. Heating multitubular steam boilers by hot gases. BABCOCK & WILCOX Ltd. June 25, 1959 [June 26, 1958], No. 20517/58. Classes 123(2) and 123(3) A boiler for a gascooled graphite-moderated marine nuclear power plant comprises two heat exchange units 1A, 1B which are connected in parallel in a closed, high pressure, carbon dioxide coolant circuit and are both associated with a common steam and water drum 101. Each unit 1A, 1B includes an elongated pressure vessel 9 and consists of three demountable sections 9A, 9B, 9C clamped together coaxially. The central section 9B, accommodating a large number of thin-walled small-diameter gas tubes, not shown, having their ends expanded into tube plates 27, 28 has, at the end adjacent the tube plate 27, transverse baffles 33A ... 33F which, each in the form of a major segment of a circle and with their straight edges vertical and spaced alternately from opposite sides of the pressure vessel, form a sinuous horizontal water preheating passage. A pair of feedwater inlet nozzles 35, welded one above the other on the inner side of the section 9B, are connected externally to supply pipes and inside the section 9B to pipes 35, leading to the space between the tube plate 27 and the adjacent baffle 33A. Riser nozzles 38 are connected by pipes 107 to the upper steam and water drum 101. Downcomer tubes 110 lead from the drum 101 to nozzles 39 and communicate with an internal space behind an arcuate baffle 43 which extends coaxially within the section 9B, between the tube plate 28 and the transverse baffle 33E and contains none of the thin gas tubes. The section 9B is provided with an upper air vent 47 having a valve 49 and with lower drain nozzles 51, 53 which are connected, through valves 54, 56 to a drainage system 56. The end section 9C, located at the tube plate 28, has a hemispherical end part, through which a flared gas inlet duct 61 extends and a cylindrical part which accommodates a tubulous superheater 65. The latter is formed of horizontally spaced platens each comprising a pair of nested sinuous tubes 71 with horizontally arranged transverse straight parts connected by return bends 72. The tubes, connected between a lower inlet header 67 and an upper outlet header 69, are located in a pass 77 formed between upper and lower chordal baffles 73, 75 carried respectively by the headers 69, 67. The ends of the baffles 73, 75 are curved upwardly and downwardly respectively at 73A, 75A to meet the pressure vessel wall. Inlet and outlet steam pipes 77, 79 connected to headers 67, 69 extend through, and are anchored to, the hemispherical part of the end section 9C, the lower header 67 being on wheels 89 and the upper header 69 being supported from the casing by roller supports 81 so that upon differential expansion the superheater 65 and the headers 67, 69 and the baffles 73, 75 can move axially of the section 9C. An air vent pipe 91 and drain pipes 93 connected respectively to the headers 69, 67 extend through the wall of the pressure vessel. A gas outlet tube 23, having a flared inner end 23A, extends through the hemispherical end of the section 9A. The common steam and water drum 101 has inner arcuate baffles 103 which define pockets 105 for receiving steam and water mixture from the risers 107. Steam and water from the pockets 105 pass to a number of cyclone separators 109 which discharge water downwardly to the bottom of the drum and steam upwardly to a scrubber 111 and into two steam conduits 113 leading downwardly to the respective superheater headers 67.