Patent GB-753103-A (GB)
Title: Improvements in vapour generating and vapour heating units
IPC: F22G7/14
Filed: 1954-08-13
Abstract: 753,103. Supporting superheaters in watertube steam boilers. BABCOCK & WILCOX, Ltd. Aug. 13, 1954 [Aug. 14, 1953], No. 23656/54. Class 123(3). In a steam boiler comprising, for example, a main bank 37, Fig. 2, of steam generating tubes, which extend from a lower water drum (not shown) to an upper steam-and-water drum and between a furnace chamber 29 and a flue gas outlet 29f, a superheater 42, comprising an upright bank of looped horizontally-arranged tubes, is located in a space 30 defined on one side by the tube bank 37 and on the other side by two further rows of steam-generating tubes 37a of larger diameter. The tubes 42 are shown arranged in rows each comprising three tubes 42a, 42b, 42c and they are located by two pairs, say, of large diameter tubes 38a, 38b also extending between the said lower and upper drums, and two further pairs of tubes 39a, 39b staggered with respect to the tubes 38a, 38b, the respective tube rows being supported and spaced, Fig. 3, by support members 64, Figs. 5 and 5A, and bridge members 65, Fig. 6, which members coact with opposed brackets 62 welded in pairs along the larger tubes 38a, 38b, 39a, 39b. The brackets 62 are of U-shape in cross-section to provide vertical slots to receive the ends of the bridge members 65 and on their opposed faces have curved surfaces 62b, 62e to mate with the superheater tubes or with, when required, the rounded ends 64d of the support members 64, the bridge pieces having central recessed portions 65a, 65b to mate with the tubes 42 and end tube-wedging portions 65c, 65d. The support members 64 have spaced holes 64b, 64c at one side to receive removable bolts, and on their upper faces they are each formed with a rectangular recessed portion 64a to receive and hold a bridge piece 65 and on their underside a recessed portion 64e deep enough to receive the projecting portions of a bridge member. In assembling a superheater, see C, Fig. 3, a support member 64 is inserted between the lowest brackets on all pairs of tubes 38a, 38b and 39a, 39b, followed by a bridge piece 65, whereupon the first row of three superheater tubes 42a, 42b 42c are sprung together and inserted through door panels 54, 54a in the front wall of the boiler so as to rest upon the said bridge pieces 65 ; the tubes are then relaxed so that the middle one engages the recesses 65a in the latter and the outer ones are engaged between the surfaces 62e, 65c of the brackets 62 and bridge pieces 65 respectively. Alternate bridge pieces and rows of tubes are now added until the tube installation is complete, see A, Fig. 3, when finally, a support member 64 in inverted position is pushed into the recesses 62b of each opposed pair of topmost brackets 62, so that the members slide over the projections on the top bridge members 65 and is locked in place by bolts inserted through the holes 64b, 64c thereof. At B, Fig. 3, support members 64 are shown used, in the absence of tubes, as spacer members ; upon the uppermost row of a group of tubes is placed a bridge member 65 followed by a reversed support member 64, a second bridge member 65, a second support member 64 and, lastly, a third bridge member 65 which accommodates the lowest row of an upper tube group. The pairs of tubes 38a, 38b and 39a, 39b are retained in spaced relationship by upper and lower collars comprising U-shaped pieces 68, Fig. 4A, which fit around adjacent tubes and straight side pieces 69 welded thereto, the furnace side of the collar pieces on the tubes 38b, 39b being provided with anchoring rods 70 for a refractory covering 71. The boiler rear wall is fitted with removable panels 53, 53a to permit inspection of the superheater.