GB717420A - Improvements in tubulous vapour generating and superheating units - Google Patents

Abstract

717,420. Water-tube steam boilers; regulating superheat. BABCOCK & WILCOX, Ltd. Sept. 3, 1952 [Sept. 5, 1951], No. 21004/51. Classes 123(2) and 123(3) In a steam boiler comprising parallel gas paths 2, 3, Fig. 1, which lead from a combustion chamber 1 and locate, the pass 2, a bank of steamgenerating tubes 7 screened by a tube bank 6 and, the pass 3, a steam-generating tube bank 10 with a screening bank 8 and intermediate superheater 9, the tubes 6, 7, 8, 10 extending, for example, between an upper steam- and-water drum (not shown) and lower water drums on opposite sides of the. chamber 1, the superheat temperature is controlled by a swinging damper 13 which is disposed in a gas pass 5 subsequent to the passes 2, 3 and is adapted differentially to vary the gas flows through the latter passes. The pass 5, which houses an economizer 4, is divided into separate passages by parallel baffles 14-18 with any one of which the damper 13 is adapted to coact. A second or auxiliary damper 27, which normally lies against a wall of the pass 5, may be provided for independently varying relative gas quantities flowing through the passes 2, 3, and, preferably, the two dampers are so arranged that they may be brought into alignment to prevent gas flow through the superheater pass 3 when starting up the boiler. In the practical embodiment of Fig. 4, the parallel gas paths 2, 3 (not shown) lead to spaces 64, 66 above the front and rear parts respectively of the upper steam-and-water drum 50. An economizer 61 extends above the spaces 64, 66, the gas flow through the lower part of the economizer being subdivided into fourteen gas passages by thirteen vertical baffles 86-89 with which co-operates a swinging damper 81. Similarly the flow through the upper part is subdivided by fourteen baffles 115-128 which are staggered with respect to the lower baffles and have associated dampers as shown, said dampers being operated simultaneously so that each coacts with one or the other of the baffles on the two sides of the pivoting axis thereof.