GB692933A - Improvements in and relating to the method of and apparatus for the generation of steam - Google Patents

Abstract

692,933. Water-tube steam boilers; superheaters. FOSTER WHEELER, Ltd. April 28, 1950 [April 29, 1949], No. 10504/50. Class 123 (ii) and 123 (iii) A steam boiler has two separate steam-generating sections, namely, a radiantheat section comprising a combustion chamber 11, Fig. 1, lined with tubes 24, 29 extending from lower water headers 30, 40 to an upper steam-and-water drum 21, either directly or through risers 22, and a convection section with upper and lower drums 48, 49 connected by two banks 50, 51 of tubes, and steam from the latter section is directed through tubes 52 to open-ended side chambers 86, 87, Fig. 4, in the drum 21 where it is condensed by feed-water which is supplied to the boiler through a pipe 96 disposed longitudinally within said drum and having branches 97, 98 terminating in nozzles 115, 116 as shown. The convection section is fed from the drum 21 through tubes 70 extending from the ends thereof to headers 71 at opposite ends of the drum 48; downcomers 48<SP>1</SP> connect the drums 48, 49, and the drum 49 is provided with a blow-down 49<SP>1</SP>. The drum 21 is also provided with communicating side chambers 90, 91 into which the steam tubes or risers of the radiant section open; these chambers are closed except for slots 104 which permit the steam to flow into separating boxes 99, 100 of square cross-section, Fig. 8, preferably fitted with cylindrical liners 114, where it is centrifuged by feedwater from the branches 97, 98 which is injected tangentially into the boxes from nozzles 105, 106 through said slots 104. From the separators the steam passes through chevron driers 112, 113 and a pipe 62 to a superheater 53, 54, the water flowing through the open bottoms of the boxes 99, 100 to the central chamber 111 of the drum and thence through outlets 120, formed in a plate 85 defining the bottom of the chamber 111, and passages 121 to downcomers 32 which depend to a header 33 connected by further downcomers 34 to the water headers 30, 40. The superheater 53, 54 is disposed between the outlet from the combustion chamber 11 and the convection tube bank 50, the the section 54 being confined by side baffles 66, 67 the first of which is fitted with dampers 68 for controlling the flow of gases through the section 54 and hence the degree of-superheat.