GB784410A - Improvements in tubulous vapour generating and vapour heating units - Google Patents

Abstract

784,410. Water-tube steam boilers; regulating superheat. BABCOCK & WILCOX, Ltd. Nov. 3,1955 [Nov. 4, 1954] No. 31979/54. Classes 123(2) and 123(3) A water-tube boiler especially for marine use comprises an oil-fired furnace 1 lined with water-tubes and disposed to one side of upright tube banks 2, 5 of water-tubes which, with the lining tubes, extend between a lower water drum 3 and an upper steam and water drum 4. Gases leave the furnace through a tube-screen 31 and flow laterally through an open pass 29 between tube walls 42, 43 into a space 46 adjacent a transverse tube wall 48. The tubes in the lower portion of the wall 48 are offset to provide a gas flow passage into a vertical pass 69 disposed behind the wall and containing superheater tube banks 78, 79. At the top of pass 69 are disposed dampers 84 by means of which the gas flow in the pass and hence the steam temperature are controlled. The gases which do not enter the superheater pass flow from the space 46 first towards and then away from the furnace in successive passages containing respectively the tube bank 2 and 5 and enter a space 67, disposed behind the superheater pass and separated therefrom by a tube wall 49, from which they flow to the stack through a damper-controlled outlet 7. The superheater pass 69 is of such large cross-sectional area, extending behind the tube bank 2 at one side and into an outward extension 71 of the front wall 41 of the unit at the opposite side, that it can accommodate a superheater with a large heat-exchange surface whereby high steam temperatures can be attained with small draught loss. In a modification, the gases from the furnace flow directly into two side-by-side passes the first of which locates a steam generating tube bank at a part disposed adjacent an open part of the second pass of relatively smaller crosssectional area whilst the second pass locates a superheater at a part disposed adjacent an open part of the first pass of relatively smaller cross sectional area which forms a section of the gas outlet flow path from the steam generating bank.