Patent GB-893372-A (GB)
Title: Improvements in tubulous vapour generating and heating units
Inventor: SCHAAP WILLEM FREDERICK CAREL
IPC: F22B21/34
Filed: 1957-07-23
Abstract: 893,372. Water-tube steam boilers. BABCOCK & WILCOX Ltd. July 18, 1958 [July 23, 1957], No. 23346/57. Class 123(3) In a top supported unit for generating steam at high pressures and temperatures the' major portions of the side, front, and rear walls 1, 2, 3 of the furnace casing are lined with contiguous steam generating tubes 4 and the other side wall 10 and the adjacent edges 2a, 3a of the front and rear walls 2, 3 are lined with steam tubes 11 which conduct saturated steam from a steam-andwater drum 7 to an inner panel of radiant steam heating tubes 18. Heated steam from the tubes 18 passes along alternate tubes of a row of contiguous tubes 20, lining the roof of the furnace chamber and the roof, side, and bottom of a lateral pass 14, to a header 21 from which the remaining tubes return to a header 22, leading to a convection superheater section 15, 15<SP>1</SP> located in a lateral pass 14, and an attemperator 16. A gas-tight metal casing 23, including panels 24, girders 25b, and T-section supports 25<SP>1</SP>, and of the type described in Specification 835,567, is mounted on the tubes 4, 11 the adjacent vertical portions of which incorporate slidable plates of a seal 38 to accommodate slight differential thermal expansion. The latter is avoided, or maintained at a relatively small value since, in operation, the temperature of the steam supply tubes 11 is substantially the same as that of the steam generating tubes 4. The tubes 11 are set in refractory material 27 held in position by studs 28 and the casing 23 is covered with insulating material 26. The steam heating tubes 18, which may comprise superheater and reheater sections, are slung from springs 39, Fig. 4, which compensate for differential longitudinal expansion between the tubes 11, 18. A seal, not shown, is provided between the casing 23 and the upper end of the tubes 18. Certain of the tubes 11 are bent inwardly at intervals at 30, and each pair of adjacent portions 30 is interconnected by an L-section beam 31 clamped to the bowed portions by G-bolts 32, the beams being separated by small expansion gaps 33. Rods inter-connect the tubes 18 to form platens of six tubes separated by expansion gaps 35. C-members, welded to two of the tubes 18 of each platen, pass through holes in lugs 37 welded to the beams 31. The inclined hopperforming extensions 11<SP>1</SP> of the tubes 11 are supported, from extensions 11<SP>1</SP> of the tubes 11, carried by buckstays 25 beneath them, by means of connectors 41. Each of the latter comprises an L-shaped, notched beam 42 connected transversely to the tubes 11 and carrying a number of adjustably mounted bolts 43 each of which passes through a hole in an adjacent lug 46 connecting a corresponding group of three extension tubes 18<SP>1</SP>. Two sets of burners 29, individually fired, are arranged in the front and rear walls 2, 3. In a modification the heater tubes 11 occupy only a part of one of the walls of the unit and the tubes 18 may be spaced to allow a degree of superheat. The superheating tubes could also be arranged in two, or more, passes. In a further modification, Fig. 8, not shown, the tubes 11 are in the form of downcomers leading to the tubes 4, alternate tubes 18 being connected to the steam compartment of the steam and water drum and the steam flowing upwardly from the remaining tubes 18 to the convection superheating section as shown in Fig. 1.