GB624585A - Improvements in or relating to vapour generators - Google Patents

Abstract

624,585. Water-tube steam boilers, &c. BABCOCK & WILCOX, Ltd. March 12, 1947, No. 6903. Convention date, March 12, 1946. [Class 123(ii)] A steam &c. boiler comprises a combustion chamber 16 and a laterally adjoining tube space 15 housing a bank of steamgenerating tubes 41 extending between an upper steam-and-water drum 38 and a lower water drum 39, said chamber and space being separated by groups 14a, 14b, 14c of steam-generating tubes 140. Upper portions of the tube group 14a form a partition 14, an extension 53 of which stops short of the rear setting wall 11 to provide a gas passage 27 from the chamber 16 to the space 15, and the other groups have upper portions spaced apart across said passage 27, the group 14b in a single row and the group 14c in two rows. All the tubes 140 depend from the drum 38 to a lower header 51 connected to the drum 39 by downcomers 52; similarly, tubes 10a, 10b, 11a, 11b, 12a, 13a, lining the setting walls, are directly or indirectly connected to the drums 38, 39. The space 15 is provided with transverse tube-cooled baffles 28, 29 extending partly thereacross to define serially connected gas passes 31, 32, 33, and these baffles are so formed with free edges 67, 68, Fig. 4, and 69, 71, Fig. 5, respectively that the gas flow is restricted to a greater extent over an upper part of the space 15 than over a lower part thereof so as to secure uniformity of flow throughout the height of the tube bank 41. A multipass superheater 56, comprising U-tubes 57, 58 connected to inlet, intermediate and outlet headers 59, 61, 62 transversely divided by partitions 91, is located in the first pass 31, and the last pass 33 is provided with a breeching 121 in its upper part leading to a dampered gas outlet 36; the breeching 121 may also extend partly over the middle pass 32. A soot hopper 34 is formed at the bottom of the tube space 15 adjacent the side wall 12 and is provided with a discharge opening 35 below each of the passes 31, 32, 33. The Specification as open to inspection under Sect. 91 describes also a desuperheater which is disposed within the lower drum 39 and comprises U-tubes having legs of unequal length extending longitudinally thereof in parallel planes between a pair of pivoting boxes, each of said planes containing at least two U-tubes of different spans. This subject-matter does not appear in the Specification as accepted.