GB873087A - Improvements in tubulous vapour generating and heating units - Google Patents

Abstract

873,087. Water-tube steam boilers; super heaters. BABCOCK & WILCOX Ltd. Dec. 18, 1959 [Dec. 19, 1958], No. 41085/58. Classes 123(2) and 123(3) In a high capacity tubulous steam generator in which a furnace chamber 1, lined with steam generating wall tubes 2, extends to a lateral gas pass 6 followed by a downpass 7 with a paralled by-pass 44, a superheater section 21, which is formed of horizontally spaced platens of sinuous tube lengths 22 nested in pairs, has a lower portion 47 located only in the downpass 7 and an upper portion 46 which extends across the downpass 7 and the bypass 44. Prolongations 26 of the tubes of the upper superheater portion 46 extend forwardly, below the floor 18 of the lateral pass 6, to mix at 27 with the rear wall tubes 2 and then line the floor 18 before being led upwardly in staggered formation at 29, across the outlet of the lateral pass 6 for bending at 30, 31 into the plane of the roofs of the lateral pass 6 and the furnace chamber 1. The prolongations 26 are subsequently taken downwardly at 32 to cover partly, with some of the tubes 2, the upper portion of the front wall 10 of the furnace chamber 1. Certain of the tubes 26 connect with an outlet header 33, the remainder being returned upwardly again to a header 35. Steam from the latter passes successively through the platens of superheater banks 36, 41 to a point of use 42, the final superheat temperature being regulated by an attemperature 40. The steam space of a steam and water drum 14 communicates with a header 58 for a row of tubes 60 which provide support for the horizontal banks 49A, 49B of a reheater 43, completed by a vertical bank 49C, as well as for the superheater section 21. The lower ends of the tubes 60 connect with a header 61 from which some tubes rise at 63 to line the rear partition wall of the by-pass 44, the remainder of the tubes 60, forming a base 62 for the by-pass, lining the front by-pass wall, and the tubes 62A, 63, which then rise in staggered relation past the outlet of the lateral pass 6, then being bent to line the roof of the downpass 7. Some of the tubes 62, 63 line the rear wall 59 of the downpass 7 at 65, the remainder provide additional support for the superheater and reheater sections 21, 43 which are also supported by the tubes 63, 65. The tubes 62, 63 lead to an inlet header 64 for the superheater section 21. The by-pass 44, controlled by dampers 45, has its rear partition wall 48 continued downwardly and outwardly to provide a dust hopper 57. Some of the tubes 2 of the rear wall of the furnace chamber 1, extending in open formation across the inlet 13 of the lateral pass 6, lead to an external header 17 connected to the drum 14, others being taken rearwardly and sidewardly below the floor 18 and then upwardly to line the opposite sides of the lateral pass 6 and connect with headers 19 which are common to the tubes 2 of the furnace chamber side walls 8, and 9 (not shown), and lead to the drum 14. Downcomer tubes 20 connect the water space of the drum 14 with a lower distributer 16 for the wall tubes Economizer sections 59 are connected to side-wall headers 67, 68 from which tubes 69 rise to cover the downpass 7 side walls and for connection to headers 70 joined by tubes to the drum 14. A rotary air heater, heated in the downpass 7 below the economizer 54, supplies air through ducts 73 to a windbox 74 for burners 12 located in the front wall 10 of the furnace chamber 1. If desired the tubes of the rear wall 11 may be arranged to form an arch 80, the prolongations 26 of the superheater 26, in this case only lining a major part of the floor 18 and, if desired, only the corresponding part of the roof of the lateral pass. With an arch not provided the tubes extensions 26 may line only the roof of the lateral pass 7 the roof of the furnace chamber being lined with steam generating tubes. Specifications 873,085 and 873,086 are referred to.