GB924137A - Improvements in or relating to heat exchangers particularly for nuclear reactors - Google Patents

Abstract

924,137. Heating water-tube steam boilers, combined with nuclear reactors, by steam. MITCHELL ENGINEERING Ltd., H. J. COLES, and J. W. SUTHERLAND. June 15, 1959 [June 19, 1958], No. 19683/58. Classes 123 (2) and 123 (3). A steam generator which is adapted to be heated by radio-active steam produced in a boiling water nuclear reactor is formed of interconnected upper and lower casings 12, 10, so that the lower casing 10, which is lined internally with stainless steel and which receives the radio-active heating steam, can be located within a shielding wall, not shown, surrounding the reactor. A plurality of stainless steel tubes 17 with closed lower ends have their open upper ends flush with the upper face of a tube plate 14 which is sandwiched between the casings 10, 12, flanges 10c, 12c of which are secured together by a ring of studs 15 and nuts 16. The bores of the tubes 17 in this manner only communicate with the interior of the casing 12. A cylindrical baffle 18, surrounding the tubes 17, is secured concentrically within the casing 10 with its ends spaced respectively from a domed-end part 10a and the tube plate 14 by means of a ring 19. Steam from the reactor, entering an inlet pipe 20 located in the casing 10 immediately above the ring 19, rises through an annular space 21 which locates catalyst beds 22 to recombine any dissociated oxygen and hydrogen into steam. The heating steam then flows downwardly within the baffle 18 over the external surfaces of the tubes 17, condensate being passed through an outlet pipe 23. A cylindrical baffle 24, extending upwardly within and for part of the length of the casing 12 from the tube plate 14, has mounted therein, a short distance from its lower end, an upper tube plate 25. Tubes 26, open at each end, are fitted into openings in the tube plate 25 each tube 26 extending into, to adjacent the bottom of a corresponding tube 17. Feed water is fed through a pipe 30 to a well 28 within the baffle 24, the water being maintained at a level above the outlet end of the pipe 29 but below shrouded openings 33 in the upper end of the baffle 24. The water is heated and vaporized as it flows downwardly through the pipes 26 and then upwardly through the annular spaces between the pipes 26, 17. The generated steam rises and passes out of slots 40 in the lower end of the baffle 24 and into an annular space 31 between the baffle 24 and the casing 12. The steam then flows inwardly through the shrouded openings 33, which act as water separators, and through a ring 36 of swirl vanes located between an outlet pipe 35 and a funnel 37 which has a narrow condensate tube 37a leading to a point below the level of the water in the well 28. An annular steam baffle 32 secured within the casing 12 has its inner edge turned down to project into the upper end of the baffle 24.