GB888089A - Improvements in vapour generators - Google Patents

Abstract

888,089. Nuclear power plant. BABCOCK & WILCOX Ltd. Nov. 1, 1960 [Nov. 5, 1959], No. 37547/59. Class 39(4) [Also in GroupXIII] A highly rigid steam generator, for use e.g. in marine nuclear plants, comprises vertically aligned upper and lower drums 21, 22 which are interconnected by a central row of riser tubes 23 and two rows of outwardly bowed downcomer tubes 24 the riser tubes 23 opening upwardly into a steam and water box 44 having outlets 46 leading to two groups of eight centrifugal separators 45 which are arranged along opposite sides of the box and which each discharge water from a lower flared position below a normal liquid level in the drum 21. Primary coolant from the pressure vessel 6 of a nuclear reactor is conveyed through a pipe 14, Fig. 1, to the uppermost of two compartments 31, 32 which are formed by a separator plate 33 arranged between an end cap 29 of the drum 22 and a thick tube plate 28 for the U-tubes of a heat exchanger 36 which extends through the drum 22. The primary coolant then flows through the rest of U-tubes to the lower compartment 32 which is connected to a pipe leading back to the pressure vessel. Steam, produced by the heat exchanger 36 and rising through the tubes 23 and the box 44 to the separators 45, ascends through scrubber units 47 mounted above the separators 45 and then passes through a further pair of elongated scrubbers 48 which are provided with a drain tube 51 and are arranged in V-formation below a central outlet connected to a steam supply pipe 49 leading to a power plant. A pipe 19, leading from the power plant. is connected to two feed distributer pipes 56 which are supported at each side of the steam and water box 44 by brackets 43 arranged over the inlet ends of the downcomer tubes 24 the outlet ends of which open into arcuate passages 39 disposed at each side of the heat exchanger 36. The passages 39 are formed between the drum 22 and two part-cylindrical baffles 38 which are welded to vertical support plates 37 for the tubes of the heat exchanger 36 and are connected to the drum 22 along their upper edges by angle sections 41 which close the upper ends of the passages 39. The lower edges of the baffles 38 are connected, at spaced intervals, to the drum 22 by angle brackets 42. The pressure vessel 6, Fig. 1, lined with lead and having an annular water filled shield tank 4, is accomodated in a rectangular recess 5 in a primary concrete biological shield 3 housed in a containment vessel 1 enclosed within a concrete housing 2 and supplies primary coolant to the heat exchanges of two steam generators 8, 8 A through pipes such as 12, 14 which are controlled by valves 13, 15 and incorporate a pump 11 or H A . The lower drums 22, 22 A rest upon saddle brackets 25 supported on shelves 20 in the primary concrete shield 3. In a modification, Figs. 6, 7 not shown. the riser tubes, opening into a base plate of the steam and water box spaced from the floor of the upper drum and the roof of the lower drum and communicates with the arcuate passages.