GB893371A - Improvements in vapour generating and heating units and an improved method of generating and heating vapour - Google Patents

Abstract

893,371. Water-tube steam &c. boilers, steam superheaters. BABCOCK & WILCOX Ltd. July 14, 1958 [July 16, 1957], No. 22566/57. Class 123(3) The rectangular furnace chamber 11 of a vapour generating and heating unit is fired through opposite walls 12, 14 which are narrower than the remaining walls 16, 18 the lower part of each side wall 12, 14 being provided respectively with a set of sixteen separately controllable, pulverized fuel, burners 42 or 52 which are arranged in rows of four as shown. Each burner set 42, or 52 is arranged further from the wall 16, which is lined with an inner row of small diameter radiant superheater tubes 60, than the wall 18 lined with a row of contiguous vapour generating tubes 72. Burners in the same vertical row are connected to respective pulverizers so that the proportion of heat absorbed by the tubes 60 and 72 can be regulated by using burners towards one side or the other of the sets 42, 52 a degree of superheat regulation being afforded by selection of upper or lower burners. The side walls 12, 14 are lined with steam generating tubes 44, 54 and the steam generating tubes 72 also line the floor 76 of a lateral pass 20 and the roof 78 of the chamber 11. Saturated steam from a steam-andwater drum 10 is fed to a lower header 62 for the radiant superheater tubes 60 through a bank of larger tubes 66 which have fins 70 and serve to locate the refractory casing of the wall 16. Superheated steam, passing through convection superheater banks 22, 24, 26, located in the lateral pass 20, and a spray type of attemperator 86, is discharged from an outlet header 84. The lateral pass 20 communicates with a down-pass 28 accommodating economizers 30, 32. In a modification, Fig. 3, the wall 16 has an outer row of downcomer water tubes 96 and an inner row of small diameter radiant reheater tubes 90 which lead to a convection reheat tube bank 104 located in the lateral pass 20. The steam tubes 72 lining the floor 76 of the pass 20 are alternately bent up to provide a gas by-pass 108 which is controlled by a damper 116. Saturated steam flows from the steam and water drum 10 to convection superheater banks 22, 24 and is discharged to an outlet header 118. In an alternative arrangement the steam tubes 72, Fig. 3, are replaced by radiant superheater tubes which are connected in series with the superheater banks 22, 24, and the radiant reheater tubes 90 are connected to tubes which line the roof 78 and the floor 76 and which lead to the convection reheater bank 104. In a further modification, in which downcomer water tubes constitute the outer row of tubes, the radiant superheater tubes 60, Fig. 1, only extend over the upper part of the wall 16, the downcomer tubes being bifurcated to allow the superheater tubes to pass through the wall 16 to a header connected to the steam-and-water drum 10. Steam from the superheater tubes 60 passes through tubes lining the roof 78 and the floor 76 and then through the convection superheater banks 22, 24, 26 and the attemperator 86. Oil, or other suitable burners; may be used. Specifications 822,817 and 893,372 are referred to.