Patent GB-886927-A (GB)
Title: Improvements in tubulous vapour generators
Inventor: EVANS RICHARD HENRY
IPC: F22B37/14
Filed: 1959-07-30
Abstract: 886,927. Steam boilers; superheaters. BABCOCK & WILCOX Ltd. July 28, 1960 [July 30, 1959], No. 26227/59. Classes 123(2) and 123(3) The invention relates to a tubulous steam generator of the kind described in Specification 877,116, wherein the upper region 1 of the furnace chamber 2 is lined with drainable horizontal tube lengths 3 of a secondary superheater which also line the side walls of the lateral gas pass 4 and the horizontal steam generating tube lengths 5 of the tube lengths of the different circuits, extending one above the other in the zone of the chamber 2 below the region 1, are connected by upright transfer tubes 6 which, distributed around the furnace chamber 2, serve to suspend the furnace chamber walls and are connected to headers 8, 9. A pair of headers 13, aligned with the headers 9 above the side walls of the gas pass and tied to the headers 8, 9 by groups of interwelded connectors 14, 15, Fig. 3, carry spaced sets 16 of upright tubes arranged similarly to the sets of tubes 6 and corresponding pairs of which, below the floor 7 of the pass 4, Fig. 2, are bent inwardly and welded together in overlapping relation and then downwardly for connection with a transverse header 17. The latter is connected by a pipe 18 to a primary superheater, not shown, which is accommodated in an upright gas pass following the lateral pass 4 and has outlet pipes 19 leading to a pair of distributers 20 for the tube lengths 3 of the secondary superheater. Horizontal buckstays 21, located near the middle and a short distance above each region or zone 1, 2 and anchored at their centres and linked to the suspension means at the adjacent wall, have their ends connected by brackets and links to the tube lengths 5 at the corners of the furnace. Buckstays 21 are provided in a similar manner at the level of the floor 7 of the pass 4 and, since there are no wall lining tubes to serve as tie bars for these buckstays at opposite sides of the pass, their corresponding ends are connected by links 24 and hinge plates 25 to the horizontal portions of the respective pair of sets of tubes 16. The secondary superheater tubes 3 are connected to the transfer tubes 6 in a manner similar to that described in Specification 877,116, with respect to the tube lengths 5 lining the upper zone of the furnace the tube sets 16 at the sides of the gas pass taking the place of the transfer tubes 6. The floor of the lateral pass 4 is supported by buckstays 27 linked at their ends to respective upright portions of the tube sets 16. In a modification, Fig. 5, headers 13, receiving steam from the headers 8, 9 through the connectors 14, 15 are connected to lower connectors 17 which lead, through pipes 18, to the primary superheater. Groups comprising pairs of tubes 19A, 19B spaced longtitudinally of the floor of the pass 4 and leading from the primary superheater at opposite sides of the pass are bent inwardly and welded together in overlapping relation and terminate in respective headers 20 connected to the tube 3 of the secondary superheater section. In a further modification riser tubes 36 from vertical steam generating tubes, Fig. 6, support the secondary superheater tube lengths 32 which over upper and lower zones help to line the rear wall and both front and rear walls respectively of a downpass 39 following the lateral pass. In an alternative form of natural circulation boiler the floor of the lateral pass is lined with extensions of the upright tubes lining the rear wall of the furnace chamber, the horizontal tube lengths lining the front and side walls of the gas pass being reversely bent at the rear and at the floor of the gas pass 4 and some of the riser tubes 36 being arranged below the lateral pass to act as tie means. Other arrangements are described in which the floor of the lateral pass is lined with extensions of the horizontal secondary superheater tube lengths. Specifications 870,735 and 884,015 also are referred to.